15208_Oxygen Concentration report

TECHNICAL SPECIFICATIONS
FOR OXYGEN CONCENTRATORS


WHO MEDICAL DEVICE TECHNICAL SERIES






Technical specifications for
oxygen concentrators




WHO Library Cataloguing-in-Publication Data


Technical specifications for oxygen concentrators.


(WHO Medical Device Technical Series)


1.Oxygen Inhalation Therapy – instrumentation. 2.Durable Medical Equipment –
standards. 3.Equipment and Supplies. I.World Health Organization.


ISBN 978 92 4 150988 6 (NLM classification: WX 147)


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Illustrations by: David Woodroffe [Illustrator], Patrick McKern [PATH]


Design & layout: L’IV Com Sàrl, Villars-sous-Yens, Switzerland.


Technical copy-editing: AvisAnne Julien


Technical specifications for oxygen concentrators ii




Contents


Acknowledgements 3


Abbreviations 5


Executive summary 6


1. Introduction 7
1.1 The role of oxygen concentrators 7
1.2 Hypoxaemia and the need for oxygen therapy 8
1.3 Background and scope of technical specifications 9
1.4 Purpose of the document 9
1.5 Intended audience for this document 10


2. Technical specifications for oxygen concentrators 11
2.1 Description 11
2.2 Technical specifications 13


2.2.1 Oxygen concentration 14
2.2.2 Flow control 14
2.2.3 Indicators and alarms 15
2.2.4 Outlets 15
2.2.5 Enclosure 16
2.2.6 Power 16
2.2.7 Documentation and compliance 17


2.3 Context-dependent considerations 17
2.3.1 Maximum flow output 17
2.3.2 Oxygen concentration output at higher altitudes 18
2.3.3 Humidification 18
2.3.4 Blended oxygen gas 18


3. Guidance regarding oxygen concentrator consumables, accessories
and other related equipment 19
3.1 Importance of pulse oximetry 19
3.2 Patient delivery accessories 20
3.3 Patient delivery consumables 20
3.4 Accessories to divide flow to multiple patients 22
3.5 Supporting equipment during power failure 23


3.5.1 Oxygen cylinders 23
3.5.2 Power supplies and conditioning 23


3.6 Optional equipment for other applications of oxygen concentrators 25
3.6.1 Anaesthesia 25
3.6.2 Bubble CPAP 26
3.6.3 Nebulizers 26


1Technical specifications for oxygen concentrators




4. Guidance for handling oxygen concentrators 27
4.1 Potential hazards 27
4.2 Installation 28
4.3 Training 29
4.4 Handling and use 29
4.5 Cleaning and decontamination 30
4.6 Maintenance 31


5. Procurement guidance for oxygen concentrators 34
5.1 Needs assessment 34


5.1.1 Define programme context 34
5.1.2 Forecast programme requirements 35
5.1.3 Customize the specifications 35


5.2 Programme planning 35
5.3 Procurement planning 36
5.4 Assessment of procurement options and procurement method 36
5.5 Manufacturers and warranties 37
5.6 Safety standards and regulatory approvals 38
5.7 Documentation 40
5.8 Manufacturer user and maintenance manuals 40
5.9 Consumables and spare parts 41


6. Areas for future research 43


Annex 1 Oxygen concentrator technical specifications 45


Annex 2 Examples of manufacturers of oxygen concentrators 49


Annex 3 Sample calculation of back-up energy requirement for an oxygen
concentrator 52


Annex 4 Glossary 53


Annex 5 Research on access to oxygen therapy in low-resource settings
(LRS) for the treatment of childhood pneumonia 54


References 57


Technical specifications for oxygen concentrators 2




Acknowledgements


Due to the concern over the lack of oxygen supplies in low- and middle-income countries,
especially in regards to the treatment of childhood pneumonia, the development of this
document was initiated. This document was prepared in line with other similar WHO
medical device publications.

Grace Wu (PATH consultant) drafted the technical specifications document under
the supervision and guidance of Adriana Velazquez Berumen of the World Health
Organization (WHO) Department of Essential Medicines and Health Products, with
additional input from Meena Cherian (WHO Department of Service Delivery and Safety),
Shamim Qazi (WHO Department of Maternal, Newborn, Child and Adolescent Health
[MCA]) and Wilson Were (WHO MCA). Additional preparation and draft-editing were
provided by: Jaclyn Delarosa (PATH), Gene Saxon (PATH), Alec Wollen (PATH), Fay
Venegas (PATH), John Ballenot (PATH), Glenn Austin (PATH), Stephen Himley (PATH
consultant), Amy Ginsburg (PATH) and Darin Zehrung (PATH).


This document builds primarily on the outcomes of a meeting of subject-matter experts
in oxygen concentrators, organized by PATH and the Bill & Melinda Gates Foundation
in Seattle on 13–14 August 2014. The goal of this expert advisory group meeting was
to build consensus on approaches to improve oxygen concentrators to treat paediatric
patients with hypoxaemia or severe respiratory distress in low-resource settings (LRS).
The meeting identified several key issues related to technical specifications for oxygen
concentrator equipment, including procurement, performance and maintenance.


A result of this meeting was a first draft of oxygen concentrator technical specifications
aimed to guide the development, purchase, utilization and maintenance of oxygen
concentrators for use in low-resource settings. Members of the group included: Mike
Eisenstein (PATH), Keith Klugman (Bill & Melinda Gates Foundation), David Mukanga
(Bill & Melinda Gates Foundation) and Muhammad Zaman (Boston University). In
addition, WHO expresses its appreciation to members of this expert advisory group
meeting that also provided feedback throughout the development of this document:
Glenn Austin (PATH), Jim Black (University of Melbourne), Jaclyn Delarosa (PATH),
Trevor Duke (University of Melbourne), Penny Enarson (International Union Against
Tuberculosis and Lung Disease), Mike English (Kenya Medical Research Institute –
Wellcome Trust Research Programme), Amy Ginsburg (PATH), Stephen Howie (Medical
Research Council), Rasa Izadnegahdar (Bill & Melinda Gates Foundation), Robert
Jacobson (Consultant), David Peel (Ashdown Consultants), Shamim Qazi (WHO MCA),
Gene Saxon (PATH), Alec Wollen (PATH) and Grace Wu (PATH consultant).


3Technical specifications for oxygen concentrators




WHO extends its gratitude to the following external reviewers for their expertise and
important feedback: Mohammad Ameel (National Health Systems Resource Centre
[NHSRC], India), Anjeneya (NHSRC, India), Prabhat Arora (NHSRC, India), Anthony
Ciccarello (Philips Healthcare), Robert Dickinson (University of Cape Town and
Northwestern University), Robert DiBlasi (Seattle Children’s Hospital and Research
Institute), Jim Gilkison (Sanrai International), Hamish Graham (University of Melbourne),
Godfrey Katabaro (Tanga Regional Referral Hospital), Jitendar Kumar (NHSRC, India),
Ludo Scheerlinck (United Nations Children’s Fund [UNICEF]) and Ofer Yanay (University
of Washington and Seattle Children’s Hospital).


We thank PATH for initiating content development and to the Bill & Melinda Gates
Foundation for financially supporting this publication.


Technical specifications for oxygen concentrators 4




Abbreviations


AC alternating current
AIDS acquired immunodeficiency syndrome
BMGF Bill & Melinda Gates Foundation
°C degree(s) Celsius
CE Conformité Européenne/European Conformity
CFR Code of Federal Regulations
CPAP continuous positive airway pressure
dB(A) decibel(s) attenuated
EN European Norm
EU European Union
FDA United States Food and Drug Administration
HEPA high-efficiency particulate arrestance
HIV human immunodeficiency virus
Hz hertz
IEC International Electrotechnical Commission
IMDRF International Medical Device Regulators Forum
ISO International Organization for Standardization
kg kilogram(s)
kPa kilopascal(s)
LPM litre(s) per minute
LRS low-resource settings
m metre(s)
mm millimetre(s)
N2 nitrogen
NHSRC National Health Systems Resource Centre
O2 oxygen
PCB printed circuit board
RH relative humidity
STPD standard temperature and pressure, dry
UNFPA United Nations Population Fund
UNICEF United Nations Children’s Fund
UPS uninterruptible power source/supply
US or USA United States of America
USAID United States Agency for International Development
USD United States dollar
V volt(s)
VAC volts of alternating current
W watt(s)
Wh watt-hour(s)
WHO World Health Organization


5Technical specifications for oxygen concentrators




Executive summary


Oxygen concentrators are a suitable and favourable option for administering point-
of-care oxygen in developing-country settings, especially where cylinders and piped
systems are inappropriate or unavailable. Even where oxygen supplies are available at
health facilities, patient access may be limited due to missing accessories, inadequate
electricity and a shortage of trained staff. Management of hypoxaemia, or low blood
oxygen saturation, is a critical component of World Health Organization (WHO) standards
and guidelines for newborn illnesses and complications, childhood pneumonia, surgery,
anaesthesia, trauma, emergency triage, obstetric care and other serious conditions
that are commonly associated with morbidity and mortality in developing countries.
Hypoxaemia is easily treated with oxygen, which is included in the WHO Model list of
essential medicines and is perhaps the only medicine with no alternative agent. Having
a reliable oxygen supply is necessary for the care of seriously ill patients to improve
the probability of survival. It is important to ensure that potentially life-saving oxygen
equipment is available and included in health planning budgets.


Oxygen concentrators provide a sustainable and cost-effective source of medical oxygen
to health facilities with reliable power. An oxygen concentrator is a medical device
that draws in air from the environment and passes it through molecular sieve beds to
concentrate room oxygen to therapeutic levels for delivery to the patient. Oxygen therapy
for the treatment of hypoxaemia involves the delivery of concentrated oxygen to the
patient to improve and stabilize blood oxygen saturation levels. It is critical to understand
the indications and clinical use for oxygen. Guidelines for the safe administration of
oxygen differ across broad applications; the required flow rate and concentration of
oxygen delivered vary depending on the patient’s age and condition. Pulse oximetry
should be used in conjunction with the oxygen concentrator to identify hypoxaemic
patients and monitor oxygen therapy to promote the efficient and safe use of oxygen.


Despite the evidence of the importance of oxygen and the existence of appropriate
oxygen supply technologies, utilization has been limited by inadequate maintenance,
training, selection and procurement of high-quality devices. Many hypoxaemic patients
in low-resource settings (LRS) still do not receive oxygen, thus improving access to
oxygen therapy should be a priority. Recognizing the need to increase the availability
of appropriate, safe and reliable oxygen concentrators in LRS, WHO collaborated with
PATH to mobilize technical advisors, clinicians, clinical engineers and manufacturers to
prepare this guidance document for the appropriate selection, procurement, utilization
and maintenance of oxygen concentrators. This document also focuses on guidance for
the appropriate use and maintenance of oxygen concentrators in an effort to increase
the availability, management and quality of oxygen concentrators and, ultimately, to
improve health outcomes in LRS. This document is intended to serve as a resource for
the planning and provision of local and national oxygen concentrator systems for use
by administrators, clinicians and technicians who are interested in improving access to
oxygen therapy and reducing global mortality associated with hypoxaemia.


Technical specifications for oxygen concentrators 6




1. Introduction


1.1 The role of oxygen concentrators


Oxygen is included on the World Health Organization (WHO) list of essential medicines,
yet it is still not widely available in developing-country settings that bear the greatest
mortality burden of seriously ill newborns, children and adults (1). Reasons for low
oxygen availability are often associated with cost and lack of infrastructure to install
and maintain reliable oxygen supply. Even where oxygen supplies are available, patient
access may be limited due to missing accessories, inadequate electricity and/or shortage
of trained staff (2–4).


Fortunately, there is compelling evidence that oxygen concentrators are a feasible and
cost-effective strategy for the administration of oxygen therapy, especially where oxygen
cylinders and piped oxygen systems are inappropriate or unavailable (5–8). Good-quality
oxygen concentrators can provide a sustainable and reliable source of oxygen to multiple
patients. Oxygen concentrators operate by drawing air from the environment to deliver
continuous, clean and concentrated oxygen. They may run for up to five years or more,
with minimal service and maintenance (see Section 4.6).


There is strong evidence on the use and effectiveness of oxygen concentrators to
increase access to life-saving oxygen and improve the overall quality of health care
in low-resource settings (LRS). Studies conducted in Egypt (9), Gambia (6), Malawi
(3,10), Nepal (11), Nigeria (8) and Papua New Guinea (12,13) have demonstrated the
utilization of oxygen concentrators to expand the availability of oxygen in health facilities
in resource-limited settings. These studies show that oxygen concentrators have been
successfully used in developing-country settings to supply oxygen in paediatric and
operating wards (1,5,8).


The advantages of oxygen concentrators have been discussed in the technical literature;
they include high reliability and low cost compared with oxygen cylinders and piped
oxygen supply systems (Table 1) (6,14). Disadvantages of oxygen concentrators include
the need for regular, although minimal, maintenance and a reliable power supply – both
of which can be addressed with effective programme planning and training. Capacity-
building and collaboration among management personnel, clinicians and technicians
are necessary to ensure effective implementation and timely maintenance of oxygen
concentrators. Oxygen concentrators are important medical devices, and systematic
approaches to ensure their quality and maintenance are vital to achieving reductions
in mortality associated with hypoxaemia.


7Technical specifications for oxygen concentrators




Table 1. Comparison of oxygen cylinders and concentrators as the basis for oxygen systems


System
Central oxygen


(pipeline system) Oxygen cylinders Oxygen concentrators
Power source required No No Yes, continuously (100–600


W, depending on model)


Transport requirement Those associated with
cylinders


Regularly; heavy and costly to
transport


Only at time of installation


Exhaustible supply Yes, if pipes are refilled from
an offsite supply facility


Yes, depending on the size,
storage pressure and patient
needs


No, continuous supply as
long as power remains
uninterrupted


Initial costsa Significant: generator and
cylinders (US$ 20 000), piping
system (US$ 10 000+),
installation, commissioning
and training


Moderate: cylinder, oxygen
flowmeter and regulator per
cylinder (~US$ 200)b


Moderate: concentrator
(US$ 300–3400)b, spares,
installation, commissioning
and training


Operational costsa Small to moderate:
maintenance, continuous refill
of pipeline by bank or tanks


High: cylinder refills and
transport from refilling
station to hospital


Small: electricity and
maintenance


User care Minimal Minimal: regular checking,
minimizes fire hazard (no
grease or flammables)


Moderate: cleaning of filters
and device exterior, and
minimizes fire hazard


Maintenance


Cost per 1000 litres oxygenc


Moderate: check for pressure
leaks with manometer
Maintenance of oxygen
pipelines to prevent leaks and
oxygen wastage
Significant: if supply facility
is onsite


Data not available


Moderate: check for pressure
leaks with gauge


US$ 10–30/kilolitre varying
with estimated oxygen
requirement and power
availability


Moderate: check for low
oxygen output with analyser


US$ 2–8/kilolitre (greater
depending on cost of
power source), varying
with estimated oxygen
requirement and power
availability


Note: All costs are approximations and not guaranteed.
a See literature for region-specific cost breakdowns (3,6,12).
b Based on current market prices for June 2015.
c Includes initial capital and operational costs, based on cost modelling performed in Gambia (6).


1.2 Hypoxaemia and the need for oxygen therapy


Oxygen is a basic requirement in order to save the lives of seriously ill patients. Oxygen
therapy is a highly effective intervention for reducing global mortality. WHO guidelines
emphasize the importance of oxygen and its broad indications for neonates (15),
paediatrics (1–8), obstetrics (14), internal medicine (16), emergency care (14,17), triage
(18), anaesthesia (14), surgery, trauma, survival services, and pandemic preparedness
(19) and treatment of other common medical conditions and illnesses affecting patients
of all ages (5).


Hypoxaemia, or low blood oxygen saturation, is a common complication of a range of
clinical conditions. Oxygen is essential for the treatment of hypoxaemia and should be


Technical specifications for oxygen concentrators 8




given to the patient to improve and stabilize blood oxygen saturation levels. The current
standard of care for oxygen therapy includes proper monitoring and training of clinical
staff regarding when and how to administer therapy. Pulse oximeters are an important
low-cost technology and the accepted standard for detecting hypoxaemia and monitoring
oxygen therapy. When combined with an appropriate oxygen supply, pulse oximetry can
promote the efficient use of oxygen.


Oxygen is critical to the treatment of hypoxaemia associated with serious conditions
contributing to the global burden of maternal, newborn and child mortality. Hypoxaemia
is the major fatal complication of pneumonia; the leading infectious cause of death in
children under 5 years of age worldwide. In 2013, pneumonia killed 935 000 children
– about 2600 children every day – and accounted for more childhood deaths than HIV/
AIDS and malaria combined (20). In addition, paediatric deaths that result from other
common serious conditions such as birth asphyxia, low birth weight, meningitis, sepsis,
acute asthma and malaria add to the substantial burden of hypoxaemia. Increasing the
availability of supplemental oxygen promises to improve health outcomes and survival.
Nonetheless, many hypoxaemic children in LRS still lack access to oxygen therapy (2–4).
Oxygen is often unavailable in primary health clinics or smaller remote hospitals and is
often lacking in district hospitals (1,21).


1.3 Background and scope of technical specifications


The WHO technical specifications for oxygen concentrators that are outlined in this
document both comply with relevant International Standards Organization (ISO)
requirements (based on ISO 80601-2-69:2014, which supersedes EN ISO 8359:2009/
A1:2012) and list additional essential requirements necessary for acceptance and
operation of oxygen concentrators in LRS. Harsh, hot and humid environments as well
as intermittent and unstable power in LRS present challenging operating conditions
that often cause premature failure of oxygen concentrators. Exacerbating this problem
is the lack of trained technicians to provide corrective and preventive maintenance and
access to spare parts, which result in device underutilization or failure.


The guidance in this document were established in an effort to address the barriers
to access of oxygen concentrators and potential causes of oxygen concentrator
failure in LRS. This document outlines key performance and technological aspects of
concentrators that are essential for successful operation in LRS.


1.4 Purpose of the document


This document provides an overview of oxygen concentrators and technical specifications
to aid in the selection, procurement and quality assurance of these devices for the
treatment of hypoxaemia in developing-country settings. Recognizing the need to
increase the quality, accessibility and availability of oxygen concentrators in LRS,
this document highlights the minimum performance requirements and technical
characteristics for oxygen concentrators and related equipment that are suitable for
the use scenarios and climates in LRS. If oxygen concentrators are manufactured in
accordance with ISO standards and properly procured using the proposed specifications


9Technical specifications for oxygen concentrators




and appropriate supply chain, then these actions will help to ensure that the end user
receives a high-quality product. Other resources needed for safe use, cleaning and
maintenance are highlighted as important considerations for implementation. It should
be noted that this document does not replace published international standards,
manufacturer instructions and maintenance manuals, which are informative materials
that should be obtained and referenced. Additional information on WHO technical
specifications for medical devices is available at www.who.int/medical_devices/en/.


1.5 Intended audience for this document


This document is intended for administrators, including policy-makers, programme
managers, hospital personnel, procurement officers, logisticians and biomedical/clinical
engineers in facilities with the responsibility of planning and supplying local, national
or international oxygen concentrator systems in LRS. Global procurement agencies
and national health products regulatory authorities may refer to this in preparation
for the regulatory clearance, procurement, management and effective supply of
oxygen concentrators to treat hypoxaemia. Manufacturers should comply with these
specifications to produce safe, high-quality and affordable oxygen concentrators that
are appropriate for use in LRS. Others may also benefit from this resource, including
health workers, clinical staff, technicians, nongovernmental agencies, academia
and those interested in defining the oxygen supply resources for reducing mortality
associated with hypoxaemia. This document also highlights areas of future work to
address current knowledge gaps regarding oxygen concentrators in LRS that may be
helpful for researchers, manufacturers and organizations.


Technical specifications for oxygen concentrators 10




2. Technical specifications for oxygen
concentrators


2.1 Description


An oxygen concentrator is a self-contained, electrically powered medical device designed
to concentrate oxygen from ambient air. Utilizing a process known as pressure swing
adsorption, an oxygen concentrator produces up to 95.5% concentrated oxygen.
Atmospheric air is drawn through a gross particle and intake filter before moving
through a compressor. The pressurized air passes through a heat exchanger to reduce
the temperature before entering sieve beds that contain zeolite, a mineral material
that preferentially adsorbs nitrogen gas (N2) at high pressures. As each sieve bed
is depressurized, N2 is released. Valves open to deliver concentrated oxygen into a
reservoir where it accumulates, and from which a flowmeter can be used for measured
and continuous release of oxygen to the patient at a specified flow rate. A process flow
diagram of a typical oxygen concentrator is illustrated in Figure 1. In general, there are
two types of oxygen concentrators: stationary and portable.


Most stationary oxygen concentrators weigh less than 27 kg and have wheels so that
they are easily movable by the user. They are self-contained devices that supply an
economical, continuous stream of oxygen at flow rates up to 10 litres per minute (LPM).
Very low flows, down to 0.1 LPM, may be delivered via the built-in flowmeter or with
additional accessories (see Section 3.4). Most concentrators that are appropriate for
health facilities can deliver at least 5 LPM and operate on alternating current (AC)
electricity, and consume approximately 280–600 watts (W), depending on the model
(see Annex 2). Separate models for 110–120 V of alternating current (VAC) (typically 60
Hz) and 220–240 VAC (typically 50 Hz) are generally available from the manufacturer
to match the voltage and frequency of the local grid power.


In general, portable oxygen concentrators have a lower output capacity (3 LPM or less),
consume less power than their stationary counterparts (approximately 40–130 W) and
are used by individual patients as ambulatory oxygen systems. Many contain batteries
capable of operating on direct current (DC). Due to their low flow capacity, they are not
suitable for simultaneous use by multiple patients. In addition, many portable devices
contain a mechanism that allows oxygen delivery only during inspiration. This type of
flow, known as pulsed-dose or intermittent flow, conserves oxygen and battery power.
It is important to note that some infants and young children may not generate enough
negative pressure during inspiration to reliably trigger oxygen flow. Nonetheless, a subset
of portable concentrators are capable of both continuous and intermittent flow.


Concentrators are designed for continuous operation and can produce oxygen 24 hours
per day, 7 days per week, for up to 5 years or more. These devices can be used at
any level of health facility to provide oxygen therapy, as long as there is a continuous


11Technical specifications for oxygen concentrators




source of reliable power and a system for regular cleaning and maintenance by users
and technical personnel alike. While most oxygen concentrators operate by the same
principles, spare parts are not interchangeable between different models. The typical
component names of oxygen concentrators and their functions are described in
Figure 1. Models also often differ in user interface features, such as device settings
alarm indicators and maintenance components.


Figure 1. Process flow and components of a typical oxygen concentrator


FAN


INTAKE
FILTER


PRODUCT
FILTER


GROSS
PARTICLE


CONTROL
CIRCUIT


FILTER


COMPRESSOR


HEAT
EXCHANGER


PRESSURE
REGULATOR


ROOM
AIR IN


VALVE
ASSEMBLY


ZEOLITE
SIEVE
BED 1


ZEOLITE
SIEVE
BED 2


PRODUCT
TANK


WARM NITROGEN-
RICH AIR OUT


POWER SWITCH FLOWMETER


OXYGEN
OUTLET


ALARM SPEAKER
ALARM


INDICATORS


EXHAUST
MUFFLER


EQUALIZATION &
CHECK VALVES


KEY


ROOM AIR


OXYGEN-RICH AIR


NITROGEN-RICH AIR


ELECTRICAL LINES


Source: Provided by PATH (2015).


Technical specifications for oxygen concentrators 12




Table 2. Typical components and their function within an oxygen concentrator


Component Other names Function
Enclosure Cabinet, interior Encases internal components of concentrator


Gross particle filter Cabinet filter, air intake filter, coarse filter Filters coarse particulates to extend intake filter
life


Compressor intake filter Inlet filter, intake filter, compressor Filters fine particles to protect compressor and/
or valves


Compressor Not applicable Pressurizes and pumps air into the system


Fan Cooling fan Circulates cabinet air and cools the compressor


Heat exchanger Aluminium pipe, coil, pipe Dissipates heat created by gas compression


Control circuit PCB, printed circuit assembly Analyses the system state and controls the valves
and compressor


Valve assemblies Solenoid, check, rotary valves Controls the flow processes for the sieve and
exhaust


Sieve beds Sieve columns, zeolite Separates gases as air is moved in and out


Exhaust muffler N2 exhaust muffler, muffler Expels and quiets the N2-rich air released back
into the room


Product tank Reservoir tank, accumulator tank, mixing tank,
product tank


Gas accumulator for providing a steady and
continuous flow


Flowmeter Flow selector Controls the delivered flow rate


Product filter Outlet, output filter, final filter Removes particulates from the product stream


Humidifier Bubble humidifier, bubbler Humidifies the delivered gas before inhalation


Oxygen monitor Low oxygen alarm, oxygen concentration status
indicator


Signals an alarm when oxygen concentration is
below a preset level


2.2 Technical specifications


The following specifications define requirements for stationary oxygen concentrators that
are appropriate for the treatment of hypoxaemia in developing countries (summarized
in Annex 1). It should be noted that these specifications are intended to be used in
conjunction with the current standard for oxygen concentrators, ISO 80601-2-69:2014
of the Medical Electrical Equipment – Part 2-69: Particular requirements for basic safety
and essential performance of oxygen concentrator equipment (see Section 5.6). Unless
otherwise noted, the following is specified at standard temperature and pressure, dry
(STPD). STPD is defined as 101.3 kPa at an operating temperature of 20 °C, dry.


For the purposes of these specifications, “shall” means that compliance with a
requirement or a test is mandatory; “should” means that compliance with a requirement
or a test is recommended, but is not mandatory; “may” is used to describe a permissible
way to achieve compliance with a requirement or test; “particular standard” refers to
the requirements for oxygen concentrators (ISO 80601-2-69:2014).


13Technical specifications for oxygen concentrators




2.2.1 Oxygen concentration
• The oxygen concentrator shall be capable of delivering a continuous flow at a


concentration of oxygen greater than 82%.


NOTE: Oxygen concentration may also be referred to as oxygen purity.


NOTE: Most concentrators currently available produce an oxygen concentration
between 82% and 96% volume fraction when operated within manufacturer
specifications. Subclause 201.12.4.102 of the particular standard requires that
oxygen concentrators must activate at least a low priority technical alarm condition
with an alarm signal if producing an oxygen concentration less than 82% volume
fraction.


• The minimum oxygen concentration shall be maintained at the maximum rated flow
rate, at 40 °C, 95% relative humidity (RH) and atmospheric pressure representing
an altitude of 2000 m above sea level.


NOTE: Testing at the rated RH and temperature simultaneously is particularly
important for oxygen concentrators since the concentration of oxygen can be
significantly reduced by high RH such as those encountered in non-air-conditioned
environments. Subclause 201.12.1.103 of the particular standard requires that
oxygen concentrators be tested under the least favourable working conditions, as
specified in the instructions for use. Check compliance with testing specified in
subclause 201.12.1.103 of the particular standard.


NOTE: In contrast to ISO 80601-2-1:2014, ISO 8359:2009/A1:2012 (hereinafter
referred to as ISO 8359) did not require that concentrators be tested under
simultaneous temperature and RH conditions. An independent study evaluated
the performance of several ISO 8359 devices under these conditions and found
that performance decreased with increasing heat and humidity (22).


2.2.2 Flow control
• The oxygen concentrator shall be equipped with at least one built-in flowmeter


with flow-rate control. If the oxygen concentrator is equipped with more than one
flowmeter, each shall incorporate independent flow-rate control.


• For paediatric use, the flowmeter shall be capable of providing a minimum flow rate
of at least 0.5 LPM. The maximum rated flow should depend on the oxygen needs
(for examples, see Section 2.3.1).


NOTE: Some 8 or 10 LPM units may only provide flow down to 2 LPM. In this case,
if there is a clinical need for lower flow rates, such as for paediatrics, additional
accessories are required (see Section 3.4).


• The oxygen concentrator shall be prevented from providing a flow rate greater than
the maximum rated flow rate.


Technical specifications for oxygen concentrators 14




NOTE: Drawing a higher flow rate than intended by the manufacturer can reduce
sieve-bed performance with resultant oxygen concentration dropping too low. It can
also result in an earlier than usual replacement of sieve beds, which will need to
be performed by trained technical personnel.


• The flowmeter shall provide continuous flow-rate control, with markings from 0 LPM
to the maximum rated flow-rate, at a minimum of 0.5 LPM intervals.


• The oxygen concentrator shall be capable of generating at least 55 kPa at all flows,
up to the maximum rated flow.


NOTE: This is to overcome pressure drops due to long oxygen delivery tubing. In
clinical practice, back pressure is added when accessories such as flow splitters and
oxygen administration tubing accessories are connected to the oxygen concentrator
outlet.


2.2.3 Indicators and alarms
• The oxygen monitor shall indicate when the oxygen concentration is less than 82%.


NOTE: An oxygen monitor helps indicate when service or maintenance is needed.
Faulty oxygen concentrators are sometimes still able to produce oxygen concentration
greater than room air, although not greater than 82%.


• The oxygen concentrator shall incorporate alarms for alerting the user of fault
conditions such as:
› low oxygen concentration (<82%)
› no flow
› high/low pressure
› low battery
› power supply failure
› high temperature.


NOTE: The above alarms help indicate when service or maintenance is needed.
These alarms may indicate the type of service needed, including changing of the
gross particle filter or blocked flow. Troubleshooting information should be included
in the manufacturer’s user manual.


NOTE: Different models may use alternative names for the same functional
component (see Table 2).


• The oxygen concentrator shall incorporate a time meter that records the cumulative
hours of device operation.


2.2.4 Outlets
• The oxygen concentrator shall have at least one oxygen outlet for direct attachment


of oxygen delivery tubing.


15Technical specifications for oxygen concentrators




• The outlets shall be barbed fittings and should be recessed or made out of materials
that will not be easily bent or broken to avoid damage.


NOTE: When moving concentrators across or between rooms, the device can be
bumped or caught on other objects, which causes weak plastic or protruding outlets
to break quickly.


NOTE: Good oxygen outlet designs are critical to the safe and effective use of
medical devices. Considering available resources in developing countries, barbed
fittings are preferred to prevent tubing misconnections.


2.2.5 Enclosure
• The oxygen concentrator shall incorporate gross particle filters to prevent dust and


grime from entering the enclosure and air inlet.


• All user-removable filters shall be cleanable. Cleaning instructions for filters shall
be included in the instructions for use.


• The enclosure shall have wheels to allow for movement of the oxygen concentrator
between rooms.


NOTE: A lightweight device, weighing less than 27 kg, is recommended based on
the average weight of current devices. Brakes are also ideal to prevent free rolls.


• The oxygen concentrator shall produce no more than 50 dB(A) of noise when
operating.


NOTE: Subclause 201.9.6.2.1.101 of the particular standard provides instruction for
measuring sound pressure levels, based on methods from ISO 3744. It is essential
that the noise level be related to patient acceptability and comfort. It is desirable to
reduce the noise level as far as possible for devices that interfere with sleeping. It
is recognized that oxygen concentrators may have both a steady sound level and
a peak sound level. The peak sound level is considered to be more likely to be
obtrusive to the patient during continuous machine performance.


2.2.6 Power
• The oxygen concentrator shall have a power efficiency of ≤70 W/LPM.


NOTE: Stationary oxygen concentrators consume a significant amount of power,
ranging from about 300–600 W. This amounts to significant energy demands if the
concentrator is used continuously over several days or even weeks.


• The oxygen concentrator shall have an electrical plug that is compatible with the
power outlets of the clinical facility and country where it will be installed.


NOTE: Electrical input requirements should be labelled on the device since
concentrators are available for different ranges of voltage and frequency.
Procurement-related documents should also specify these requirements, including
the voltage, frequency and type of plug needed.


Technical specifications for oxygen concentrators 16




2.2.7 Documentation and compliance
• The oxygen concentrator shall be supplied with an appropriate user manual (see


Section 5.8).


• The oxygen concentrator shall be supplied with an appropriate service manual with
full details of advanced maintenance and a list of spare parts (see Section 5.8).


• The oxygen concentrator shall comply with the ISO 80601-2-69:2014 (which
supersedes ISO 8359), or its equivalent (see Section 5.6).


NOTE: Devices compliant with ISO 80601-2-69:2014 are not expected to enter
the market until 2017 or later. The requirements specified in this document must
still be applied to existing concentrators, as of June 2015, which comply with ISO
8359. With careful selection and planning, existing models of concentrators can
be sustainably implemented in LRS (7,22–26).


• The oxygen concentrator shall be approved by a national regulatory authority.
Stringent regulatory processes include clearance by the United States Food and
Drug Administration (FDA), Conformité Européenne/European Conformity (CE)
marking or appropriate national regulatory clearance from other members of the
International Medical Device Regulators Forum (IMDRF) (see Section 5.7 for full
documentation requirements to demonstrate this compliance).


NOTE: The IMDRF is an international effort to harmonize medical device regulation;
in 2015, members include Australia, Brazil, Canada, China, the European Union
(EU), Japan, the Russian Federation and the United States. More information can
be found at http://www.imdrf.org/.


2.3 Context-dependent considerations


The following context-dependent guidance is based on WHO guidelines on oxygen
therapy and must be adjusted appropriately based on an oxygen needs assessment
(see Section 5.1).


2.3.1 Maximum flow output
Oxygen concentrators are available as 3, 5, 8 and 10 LPM units. An oxygen needs
assessment is critical to determining the maximum flow that an oxygen concentrator
should deliver. In general, a 5 LPM or more unit is able to support at least two paediatric
patients with hypoxic acute respiratory illness simultaneously. This assumes that each
child receives at most 2 LPM of un-humidified air, as long as nasal prongs or nasal
catheters are used (16). A 5 LPM machine may also support adults and older children.
An 8 or 10 LPM device may be capable of use for indications with other supporting
equipment (see Section 3.6) or sufficient to support up to four paediatric patients.
An oxygen concentrator unit that delivers between 1 and 10 LPM would be the most
versatile for surgical care applications based on current WHO guidelines (14).


17Technical specifications for oxygen concentrators




2.3.2 Oxygen concentration output at higher altitudes
At altitudes higher than 2000 metres above sea level, device performance requirements
at high temperature and humidity need not be as stringent as described in previous
sections. At these altitudes, environmental conditions rarely reach up to 40 °C and 95%
RH simultaneously (i.e. temperature and humidity tend to decrease at higher altitudes).
However, oxygen partial pressures in the atmosphere are lower at higher altitudes.
Therefore, patients at facilities in higher altitudes may require higher flow rates for longer
duration for adequate therapy compared to patients at sea level.


2.3.3 Humidification
Consult clinical guidelines to determine if humidification is needed. Per WHO guidelines,
humidification is not required when oxygen is used at low flow rates up to 2 LPM with
nasal prongs or nasal catheters in children under 5 years of age (16). Furthermore,
humidification may not be necessary when oxygen is delivered in tropical climates
by a concentrator rather than a cylinder, since concentrators provide oxygen at room
temperature whereas cylinders deliver cold oxygen.


Humidification may be required for high-flow oxygen needs greater than 2 LPM or if
oxygen bypasses the nose, such as when nasopharyngeal catheters or tracheal tubes
are used (23). In this case, a humidification bottle provided by the manufacturer must
be connected between the concentrator and the patient-breathing circuit. Humidifiers
typically have threads for direct attachment to concentrators with threaded outputs
or require a humidifier adapter for concentrators with oxygen barbs. The water in the
bottle must be changed regularly in order to prevent contamination, and flow to patient
checked at every change to detect humidifier-related oxygen leaks.


2.3.4 Blended oxygen gas
Per WHO guidelines on neonatal resuscitation, premature infants and neonates may
require 30% oxygen in order to prevent oxygen toxicity. If no source of blended oxygen
is available, in the case of premature infants, it is better instead to use room air with
normal 21% oxygen.


To provide 30% oxygen from a near-100% oxygen source, an air-oxygen blender device
may be used. However, most oxygen concentrators cannot be used with air-oxygen
blenders because they do not provide sufficient pressure. This is because air-oxygen
blenders usually require a high-pressure oxygen source (typically 300–450 kPa), which
is not usually available in LRS. High-pressure oxygen is available from cylinders and
piped oxygen systems, but not from oxygen concentrators (<140 kPa).


Alternatively, blended oxygen can be delivered by some continuous positive airway
pressure (CPAP), anaesthesia and mechanical ventilator devices. In particular,
concentrators with an air outlet can be made into a source of blended oxygen gas in
the form of bubble CPAP (see Section 3.6.2) and are commercially available.


Technical specifications for oxygen concentrators 18




3. Guidance regarding oxygen concentrator
consumables, accessories and other
related equipment


This section highlights the other important medical equipment that is needed in
conjunction with the oxygen concentrator to safely provide oxygen therapy.


3.1 Importance of pulse oximetry


Hypoxaemia can be detected by monitoring the oxygen saturation of the patient with
a pulse oximeter (Figure 2). Monitoring oxygen saturation is important to determine
whether oxygen treatment is effective and to prevent overtreatment. While a blood gas
analyser can be used to determine the partial pressure of oxygen in blood, a simpler,
inexpensive and non-invasive method is pulse oximetry. Pulse oximetry is the preferred
method to measure the oxygen saturation in arterial blood (16). In one study, the
combination of pulse oximetry and oxygen was associated with a reduced death rate of
35% in children admitted with pneumonia (24). When pulse oximetry is not available,
the necessity of oxygen therapy should be guided by clinical signs, even though they
are less reliable (16).


Various pulse oximeters are available in the market. Either bench-top (AC-powered) or
hand-held pulse oximeters can be used, depending on the financial, electrical and staff
resources available. Hand-held oximeters are cheaper than their larger counterparts,
but most hand-held oximeters have batteries that require replacement, which could
be very easily lost, stolen or unavailable in certain LRS. Where theft or loss of hospital
equipment is a major risk, it may be sensible to secure the oximeter in one location
within the ward, within reach of the sickest patients. An alternative is to have a locked
chain securing the oximeter to a bracket on a wall or bench, with the key kept by the
nurse in charge of each shift.


Oximeter accessories include batteries, battery chargers and the sensor probe. It is
suggested that the sensor probe be reusable, not disposable and specified for long
life if at all possible. The lifespan of sensor probes can be problematic in LRS and
suggestions for improving their design have been discussed (25). Reusable probes are
generally designed to clip onto the end of a patient’s finger, but some are designed to
clip onto the ear lobe. The fingertip clip probes are available in adult and paediatric
sizes and can be used on a finger, a toe, an earlobe or even across an infant’s foot,
depending on a patient’s size and the signal achieved from peripheral blood flow at the
particular anatomic location.


19Technical specifications for oxygen concentrators




For additional information, refer to WHO resources on pulse oximetry, including medical
device technical specifications (http://www.who.int/medical_devices/management_use/
mde_tech_spec/en) and training manuals (http://www.who.int/patientsafety/safesurgery/
pulse_oximetry/tr_material/en) (26–28).


Figure 2. Setup of a typical oxygen concentrator, pulse oximeter and connection to the patient


Source: Illustration by David Woodroffe. Adapted with permission of the International Union Against Tuberculosis and Lung Disease, from Duke et al. (5). Copyright © The Union.


3.2 Patient delivery accessories


To deliver oxygen from the concentrator to the patient, oxygen outlet adaptors and oxygen
delivery tubing are necessary in addition to replaceable nasal prongs and/or catheters
(Figure 3). The concentrator oxygen outlet(s) should have a ¼-inch barbed fitting (or
equivalent) for direct attachment of oxygen tubing to the patient. Oxygen tubing should
be kink resistant and kink free and have standard connectors.


3.3 Patient delivery consumables


Therapeutic levels of oxygen are delivered to the patient via oxygen tubing and a
breathing device such as nasal prongs, nasal catheters or oxygen masks. Nasal prongs
and nasal catheters are consumables that are not recommended for reuse between
patients by the manufacturer. If nasal prongs are to be reused, cleaning and disinfection
protocols must be followed (see Section 4.5).


Technical specifications for oxygen concentrators 20




In children with hypoxic respiratory illness, it is recommended that nasal prongs are
used (16). The distal prong diameter should fit well into the nostril (1 mm for premature
infants; 2 mm for neonates up to 10 kg).


Figure 3. Nasal prongs


Source: World Health Organization (2013) (16).


Nasal prongs are preferred, however, nasal catheters can also be used (Figure 4) (16). If
nasal catheters are used, French size 6 or 8 can be used in neonates and infants (16).


Figure 4. Nasal catheters


Source: World Health Organization (2013) (16).


21Technical specifications for oxygen concentrators




Due to their relative inefficiency and low patient acceptance, oxygen masks are not
ideal in locations where oxygen is scarce or for patients that require prolonged oxygen
therapy. Oxygen masks require higher flows than nasal prongs or catheters to achieve
similar inspired oxygen concentrations, and if lower flows are used, carbon dioxide (CO2)
builds up in the mask and the patient will re-breath their exhaled CO2.


3.4 Accessories to divide flow to multiple patients


The flow rate of delivered oxygen must be continuously adjustable by the user. This is
necessary because oxygen flow needs require adjustment over the course of treatment
and is particularly important for premature newborns in whom excessive oxygen therapy
causes harm (29). Furthermore, patients are started at different flow rates depending on
their age, clinical condition and the type of breathing device used (30–33).


While ISO 80601-2-69:2014 specifies oxygen concentrator performance and safety
requirements for single patient-use, concentrators can be used with multiple patients.
The options for dividing flow to multiple patients are as follows. First, some concentrators
have two built-in flowmeters, with two corresponding oxygen outlets, to treat two patients
simultaneously. This method avoids the need for additional user assembly, but is also
limited to a maximum of two patients that can be treated at the same time. Only some
concentrators designated as paediatric have built-in flowmeters capable of titrating
oxygen to very low flows (0.1–0.2 LPM; see Annex 2). Second, flowmeter stands
consisting of from two to five mounted meters can be used (see Figure 5). This has the
advantage of being more familiar to clinical staff who are used to using flowmeters on
cylinders and allows precise titration of flow to each individual patient (including down
to 0.1 LPM).


Figure 5. Example flowmeter stand


Source: Republished with permission of Maney Publishing, from Duke et al. (2010) (7); permission conveyed through Copyright Clearance Center, Inc.


Technical specifications for oxygen concentrators 22




A four-way flow splitter assembly has been used as a method to split flow. It consists of a
four-way flow splitter block, nozzles for 0.5, 1 and 2 LPM and blanking plugs (Figure 6).
Flow splitters are less preferred than flowmeter stands or built-in paediatric flowmeters,
since the corresponding blanking plugs are very easily lost or misplaced. Moreover, flow
splitters use nozzles that deliver oxygen at a single fixed rate.


Figure 6. Example flow splitter, nozzles and blanking plugs


Source: Illustration by David Woodroffe. Adapted from World Health Organization (1993) (46).


3.5 Supporting equipment during power failure


3.5.1 Oxygen cylinders
In the event that all available power sources fail or when the concentrator has been
sent for repair, a back-up oxygen cylinder is essential to ensure continuity of oxygen
treatment. The cylinder must be safely secured on a wheeled trolley and have a prefitted
oxygen flow regulator and cylinder contents gauge. If local cylinders do not have hand-
actuated valves, an oxygen cylinder valve key chain secured to the trolley is needed.


Oxygen cylinders must be regularly checked to make sure that they are full and
immediately ready for clinical service at every staff shift change. In addition, cylinders
usually need to be transported to and from the bulk supply depot for refilling.


3.5.2 Power supplies and conditioning
Operation of oxygen concentrators depends on a reliable and continuous AC electricity
power supply. It is also important that the concentrator is protected from voltage
fluctuations, including power sags and surges/spikes. While ISO-compliant devices
include basic power protection, repeated exposure to such poor-quality power can cause
shut down, underperformance or permanent damage that requires repair by a skilled
technician earlier than expected. Therefore, it is recommended that back-up power


23Technical specifications for oxygen concentrators




supplies, such as an uninterruptible power supply (UPS) and/or battery bank systems,
are also considered during the procurement of oxygen concentrators.


At a minimum, a voltage stabilizer and surge protector are recommended to counter
the poor-quality power that causes cumulative damage to the device over time. The
voltage stabilizer should accept a minimum range of voltage that is ± 20% of the rated
input. The surge protector usually has a visual indicator to signal its status, such as
a green light for “protection present”, and is certified to International Electrotechnical
Commission (IEC) standard 61643-11 or its substantial equivalent (e.g. Underwriters
Laboratories standard 1449).


Where mains power1 failures are common, back-up generators can provide back-up
power for hours, even days. However, in practice generators are problematic due to
insufficient (and expensive) fuel supply. Where there are relatively brief failures of
mains electricity, a UPS can be more appropriate. A UPS is a packaged unit consisting
of a battery (or batteries), charger, surge protector, inverter and control circuitry that
automatically switches between the grid and batteries. Some high-end models include
an additional voltage stabilizer to accept a wide input range of voltage before switching
to battery power. Because a concentrator has a starting wattage that is two or three times
greater than its rated operating wattage, a UPS should be sized to meet that starting
wattage. The internal batteries in a UPS generally only last for a few minutes to half an
hour at most, so a UPS is not appropriate where the mains power supply is interrupted
for longer periods of time.


To provide back-up power of 30 minutes or longer, a battery bank system can be used.
A battery bank typically consists of batteries, a charge controller and an inverter (34).
The batteries can be charged via mains electricity. Two parameters dictate the hours of
backup provided: the total energy stored by the batteries, measured in watt-hours (Wh),
and the operating wattage of the concentrator. Each component must be adequately
sized for the concentrator; therefore, it is useful to work with a trained battery technician
prior to setting up a battery bank. An example of how to calculate the back-up energy
requirements for an oxygen concentrator is shown in Annex 3.


The number of batteries needed depends on the characteristics of the concentrator and
the average duration of power outages. For example, in Gambia, a battery bank system
was developed to provide continuous operation for a 350 W concentrator with as little
as four hours of mains electricity available per day. Their system utilized eight lead-acid
batteries (6 V sealed, maintenance-free, deep-cycle lead-acid) with a 50-A (ampere)
charger on mains electricity (34). All components were designed to last five years, but the
battery cells may wear out sooner depending on power cycles and ambient conditions.


In areas with especially unreliable or unavailable mains electricity, solar panels can
be used to charge battery banks (Figure 7). This has been demonstrated as a cost-
effective solution that offers continuous power, even during mains electricity outages
of 30 minutes or longer (34,35). To set up these alternative power systems, the power
requirements must be determined in the setting of use and an adequate support system
for installation, training and maintenance must be defined. This should be done by local
engineers and local suppliers of alternative power sources. The economics of these


1 Also known by various terms, including mains electricity, AC power line, grid power, and grid electricity.


Technical specifications for oxygen concentrators 24




systems, including sizing, costing and payment is usually discussed with manufacturers
and local suppliers of alternative power sources.


Further field experience of such systems will provide an even better idea of the level
of specification required to make them sufficiently robust over the expected lifetime
of the system. For additional guidance and training on sustainable energy technology
options, specifications, training and maintenance, see http://www.poweringhealth.org/
index.php/topics/technology/design-and-installation.


Figure 7. Oxygen concentrators can be powered with solar-powered battery banks


Source: Illustration by David Woodroffe.


3.6 Optional equipment for other applications of oxygen concentrators


Some oxygen concentrators can be used for other medical applications besides
oxygen therapy. While some applications are possible through built-in features, other
applications require additional equipment. The appropriate clinical guidelines and
technical recommendations should be referred to, if available.


3.6.1 Anaesthesia
Oxygen concentrators can be used in some, but not all, anaesthesia machines. There
are two different systems available for delivering anaesthetic gases and vapours to the
patient, with which oxygen concentrators have been used: draw-over and continuous
flow. In draw-over systems, volatile agents or compressed medical gases are added to
an air stream that is delivered to the patient. The air is driven by the patient “drawing”
in air through the system, rather than by a source of compressed oxygen, as is used in
continuous flow anaesthesia systems. Therefore, oxygen concentrators can be used in


25Technical specifications for oxygen concentrators




draw-over systems. In contrast, not all continuous flow anaesthesia machines can work
with oxygen concentrators since most concentrators do not produce sufficient pressure.
Nonetheless, some continuous flow anaesthesia machines are designed to operate with
oxygen concentrators (36).


Overall, if oxygen concentrators are used as the primary oxygen source for anaesthesia,
there must be a back-up power supply (such as a generator or UPS) or cylinder
supply present to continue delivery in the event of a power failure. Furthermore, it is
important to determine whether the concentrator can deliver oxygen at the necessary
concentration and pressure required by the type of anaesthesia system used. For
additional information, refer to the WHO manual Surgical care at the district hospital
(14), available at http://www.who.int/surgery/publications/en/SCDH.pdf and Integrated
management for emergency and essential surgical care toolkit (17), available at http://
www.who.int/surgery/publications/imeesc/en.


3.6.2 Bubble CPAP
CPAP is a respiratory technique to provide airway support in the form of positive
pressure, primarily for premature babies with respiratory distress syndrome. Bubble
CPAP is a simple and inexpensive form of CPAP that can be made using standard
nasal prongs and an oxygen concentrator (23). However, in premature neonates less
than 32 weeks of gestational age, blended gas is required as it is not safe to administer
high oxygen concentration due to the risks of oxygen toxicity, including retinopathy of
prematurity, brain damage and chronic lung injury. As a result, oxygen concentrators
without blending functionality are not suitable for CPAP in premature infants since
concentrators do not generate enough pressure to be used with an air-oxygen blender
(see Section 2.3.4). However, certain concentrator-based bubble-CPAP systems have
been designed to provide blended oxygen gas, having been demonstrated in neonatal
wards (37). For additional information, refer to the WHO Manual on clinical use of oxygen
therapy in children (in preparation) for clinical guidelines (23) and the WHO Technical
specifications for medical devices for related equipment (26).


3.6.3 Nebulizers
A nebulizer is a device that entrains aerosolized liquid medication into inhaled air in
order to deliver medication to the lungs. Examples of drugs that have been aerosolized
and delivered orally or intra-nasally are surfactants, steroids, anti-inflammatory drugs,
antibiotics and vaccines. There are three types of nebulizers currently available: jet
nebulizers; ultrasonic nebulizers; and vibrating mesh membrane nebulizers.


If jet nebulizers are used, then concentrators with a built-in nebulizer function or that
can provide high enough oxygen outlet pressure to power a nebulizer can be used. Some
concentrators have an additional air outlet to supply pressurized air for a nebulizer (see
Annex 2). Such concentrators may reduce the need for other dedicated equipment and
infrastructure to provide pressurized air.


Technical specifications for oxygen concentrators 26




4. Guidance for handling oxygen concentrators


This section highlights key considerations when installing, using and maintaining
oxygen concentrators. This section does not intend to replace manuals provided by the
manufacturer, which are the primary sources of information and must be referenced.
General procedures are described to exemplify the maintenance resources required to
ensure the proper functioning of oxygen concentrators.


The WHO template for medical device technical specifications always requests that
service and operating manuals be delivered with the equipment. User and maintenance
manuals must be obtained when purchasing, and are essential learning, training and
troubleshooting materials.


It is important to carefully read and refer to the user manual instructions for proper
operation of the oxygen concentrator. These manuals contain information on general
operation and indications for use as well as instructions for safety, cleaning, care and
routine maintenance. It is important to make arrangements to translate the user manual
into the local language.


4.1 Potential hazards


Oxygen concentrators produce a high concentration of oxygen, which increases the
danger of fire for other objects, causing them to burn more readily. Manufacturers must
comply with international safety standards that require mechanical safeguards and
warnings to address these fire hazards. The following fire safety and hazard precautions
are highlighted and should be addressed during installation and training of clinical and
technical staff:


• immediately replace damaged electrical cables or plugs;
• utilize firebreak connectors to stop the oxygen flow in the event of fire;
• set the concentrator power switch to “off” when is not in use;
• when not in use, do not leave nasal catheters or prongs in contact with bed sheets


or blankets – this is an infection control hazard as well as a fire hazard if the
concentrator is turned on, as the oxygen will make the bedding material much
more flammable;


• keep anything that might create a spark or flame, such as cigarettes, candles,
lanterns, portable heaters, stoves and electrical appliances, well away from
concentrators, cylinders and tubing;


• do not use oil, grease or petroleum-based products on or near the unit, as these
increase the risk of explosion and fire;


• place the concentrator on a flat surface to prevent inadvertent rolling or damage
to the compressor.


27Technical specifications for oxygen concentrators




4.2 Installation


Prior to installation, manufacturer operating manuals and documents must be read
and understood. The following is a non-exhaustive list of key procedures to perform for
installation of the oxygen concentrator:


• note and report any signs of external or internal damage;
• avoid placing the unit in a confined area – place the unit so that all sides are at least


30 centimetres away from a wall or other obstruction to ensure adequate airflow to
the device and heat dissipation;


• avoid placing the unit in direct sunlight;
• position the unit away from all potential fire hazards, including curtains or drapes,


hot air registers, heaters and fireplaces;
• record the number of hours on the hour meter;
• verify that the electrical plug is compatible with the socket to be used;
• verify that the oxygen concentration level is within specifications when the device


is operated with all accessories connected at maximum flow;
• verify that all specified alarms, including power failure and battery alarms, are


operational (see Section 2.2).


While an oxygen concentrator is easily movable by an individual, oxygen concentrator
units may be installed in a fixed position to prevent damage, loss or removal to another
room. The concentrator can be located some distance from the flowmeter assembly.
The flowmeter assembly should be located conveniently on the wall near the nurse’s
station. A conduit to fix oxygen tubing against the wall can be installed to deliver oxygen
to the individual patient beds (Figure 8).


Figure 8. Example setup of an oxygen concentrator in a paediatric ward



Source: Illustration by David Woodroffe.


Technical specifications for oxygen concentrators 28




4.3 Training


High staff turnover and lack of training could translate to impeding oxygen concentrators
from receiving the preventive maintenance required to function properly. A system for
training clinical and technical staff is essential, especially since high staff turnover can
disrupt safe and effective device use (24).


Clinical users, including nurses and doctors, should be instructed and trained to perform
the following:


• identify when and which patients need oxygen therapy;
• give the appropriate amount of oxygen, in the correct manner, according to clinical


oxygen therapy guidelines;
• determine device use, both individual and multiple-patient use;
• manage day-to-day user maintenance and care of equipment;
• check that oxygen flows through the nasal prongs with a bubble test (Section 4.4).


Technicians and engineers (e.g. hospital, clinical and biomedical) should be trained
by the manufacturer, supplier and/or experienced users. Note that in addition to
information, some manufacturers may have useful instructional videos available online.
Training for technicians and engineers performing regular maintenance and service
checks should include:


• name and function of all components;
• regular maintenance and service checks;
• device operation and safety;
• routine monitoring of oxygen concentration and outlet pressure;
• performance verification and troubleshooting;
• repair and management of spare parts.


4.4 Handling and use


Prior to use, an understanding of both the clinical guidelines and appropriate equipment
is necessary (see Section 1). In general, concentrated oxygen is delivered to the patient
such that their oxygen saturation stabilizes and is maintained within normal ranges.
Exposure to too much or too little oxygen can harm patients, especially neonates (23).
To monitor oxygen therapy, pulse oximetry should be used (see Section 3.1).


The bubble test is a simple method to quickly check for gross leaks in the oxygen
connections to the patient (23). All users of oxygen concentrators should be trained to
conduct this test. To perform this test, the distal end of the nasal prongs or catheters
is submerged into a beaker of clean water (see Figure 9). Bubbles will appear if gas
is flowing through the nasal prongs. If not, all oxygen delivery connections should be
checked. Note that the bubble test does not indicate whether the oxygen purity meets
specifications; oxygen purity can be verified by the oxygen monitor or an oxygen analyser.


29Technical specifications for oxygen concentrators




Figure 9. Bubble test to check for gross leaks


Source: Republished with permission of Maney Publishing, from Duke et al. (2010) (7); permission conveyed through Copyright Clearance Center, Inc.


4.5 Cleaning and decontamination


Cleaning and decontamination procedures should be followed according to manufacturer
recommendations and standard clinical practice. Cleaning can be done easily by the
user, including nurses or assistants. No special training is required to clean the oxygen
concentrator; the user only needs to be shown how to correctly remove, wash, dry
and replace the gross particle filter of the oxygen concentrator (see Figure 10). If the
environment is particularly dusty or dirty, then the gross particle filter and device exterior
must be cleaned more frequently, at least twice per week and following every dust storm
(see Table 2 for alternative names that manufacturers use for these filters).


Figure 10. The gross particle filter on a concentrator must be removed and cleaned weekly or more often if in a
dusty or dirty environment


Source: Republished with permission of Maney Publishing, from Duke et al. (2010) (7); permission conveyed through Copyright Clearance Center, Inc.


Technical specifications for oxygen concentrators 30




In general, the filter can be cleaned with a mild detergent, rinsed with clean water, dried
and replaced. A spare filter is inserted if the concentrator is being used during cleaning.
The gross particle filter may be reused after each cleaning but should be replaced if
visible degradation occurs. Users should refer to the manufacturer for cleaning and
replacement protocols.


Similarly, the exterior of the oxygen concentrator should be wiped according to the
manufacturer’s instructions, disconnected from the power supply. Manufacturers
generally recommend cleaning using a mild detergent or cleaning agent. Allow the
solution to remain on the surface for 10 minutes and then rinse off and dry.


Manufacturer recommendations are that nasal prongs are not to be reused. However,
this may not be practical in some settings and efforts to publish standard protocols for
safe reuse are under way (23). Cleaning and disinfection protocols should always be
followed if nasal prongs are reused, and requires: cleaning with soap and water; soaking
in dilute bleach solution; rinsing in clean water; and allowing to dry in room air (23).
An effective cleaning solution can be created by mixing undiluted bleach (from 5% to
5.25% sodium hypochlorite) to water in a ratio between 1 : 100 and 1 : 10.


When humidifiers are used, they should have clean water replaced daily and be soaked
in dilute bleach for 15 minutes weekly (and between patients), and then dried (23).


4.6 Maintenance


Regular maintenance and specified service are vital to the long-term operation and
proper functioning of oxygen concentrators. Keep in mind that concentrators are
designed to run continuously for days. While the compressor is the primary moving
component and most subject to wear over time, it may be repaired or replaced if
available from the manufacturer (see Section 5.5). An analysis of an oxygen concentrator
fleet in Gambian hospitals demonstrated that the useful lifetime of concentrators can
be up to seven years or more with proper maintenance and repair (4,38).


To maintain optimal performance over time, regular maintenance by both clinical
and technical staff alike is required. In addition, maintenance should be scheduled,
performed and documented by a trained technician at least once per year (ideally
every three to four months). The frequency of maintenance checks varies by model,
use and environment, but should be done at least annually or every 5000 hours of use
(see Section 5.5). More frequent maintenance is needed for hot, humid and/or dusty
operating environments. Training in basic concentrator maintenance, including how
each component functions, should be provided by an experienced technician or by
a service representative from the manufacturer. Maintenance can be performed by
a trained technician, but a manufacturer may request that the device be submitted
for specialized repair if a problem cannot be addressed. Instructions for advanced
maintenance tasks should be detailed in the manual provided by the manufacturer.


31Technical specifications for oxygen concentrators




Regular maintenance checks on the oxygen concentration output with a calibrated
oxygen analyser is essential and must be carried out by a trained technician at least
once per year, and every three to four months if possible. During these checks, it should
be verified if the oxygen concentration is within operating range. This can be done
with a calibrated oxygen analyser. As necessary, the pressure output is checked with
a pressure gauge. These pressures may include output delivery pressure, pressure in
the product tank and pressures in the sieve-bed ends at various points of the pressure
cycle. The bubble test may also be performed as a quick check of connections for gross
leaks (see Section 4.4).


Performance outside the normal range indicates that internal components may need
replacing. A spare oxygen concentrator should be available for exchange, so that the
faulty oxygen concentrator can be examined. The sounds produced by the concentrator
also provide information about performance status. If the compressor is particularly
loud, it likely needs servicing. Additional troubleshooting and repair tasks may involve
disassembling the equipment and replacing components. The general components
of oxygen concentrators are illustrated and described in Figure 1 and Table 2. An
understanding of each of these components and their function greatly enhances the
technician’s ability to properly maintain, diagnose and repair a concentrator.


It is indispensable that the procurement document indicates that equipment be delivered
by the manufacturer along with a service manual in addition to the user manual (see
Section 5.8). Furthermore, the manuals should be made available in the local language
to facilitate use. The service manual should include troubleshooting as part of corrective
maintenance. It is important that information on the manufacturer’s technical support
department is attached to or on a sticker on the equipment in case something is not
working properly or to request spare parts. Information on local distributors who should
have spare parts and/or technical personnel that can provide maintenance support
should also be provided. All this contact information is obtained at the time of purchase
and should be available where the equipment is used. If contact can be established via
email, it will allow the user to receive updates on equipment and service manuals. In
addition, technical support should offer troubleshooting assistance and recommends
spare-parts inventories. A sample troubleshooting guide to some of the more common
problems found with oxygen concentrators is provided in Table 3.


Technical specifications for oxygen concentrators 32




Table 3. Sample troubleshooting guide for hospital engineers and service technicians


Problem Probable cause(s) and solution(s)
The concentrator does not turn on No mains power.


Inspect and check power cord, electrical connections, circuit breaker (if equipped),
internal fuse (if equipped; sometimes located on the PCB), on/off switch, PCB.


The concentrator operates, but the
compressor shuts down intermittently


Check gross particle filter, cabinet fan, capacitor for the compressor, cabinet thermal
switch (if equipped), valve(s), PCB.
Compressor may have a faulty internal switch.


The concentrator’s compressor does not
turn on


Inspect and check electrical connections to the compressor, capacitor and PCB.


The concentration is within
specifications, but flow fluctuates


Check all filters and replace if necessary.
Pressure regulator needs to be adjusted, repaired or replaced.


The concentration is within
specifications, but the oxygen monitor
indicates low concentration


Tubing to oxygen monitor is kinked or oxygen monitor is faulty.
Repair tubing or replace sensor.


The concentrator runs, but oxygen
concentration is low


Check all filters and replace if necessary.
Check compressor pressure and flow output; replace or rebuild if necessary.
Sieve beds may be faulty and require replacement.


The concentrator overheats Check ventilation fan operation; replace if necessary.
Inspect and wash gross particle filter.
Power may be in an overvoltage or undervoltage condition, check the UPS (if
installed).


Oxygen does not flow out of the
concentrator


Check system power.
Inspect oxygen tubing and cannula for kinks or plugs.
Check all filters and replace if necessary.
Check internal tubing and fittings for leaks or kinks.
Check compressor pressure and flow output; replace or rebuild if necessary.


PCB, printed circuit board; UPS, uninterruptible power supply
Source: Adapted and republished with permission of Maney Publishing, from Duke et al. (2010) (7); permission conveyed through Copyright Clearance Center, Inc.


33Technical specifications for oxygen concentrators




5. Procurement guidance for oxygen
concentrators


Improving health outcomes through the implementation and utilization of oxygen
concentrators is possible with time and planning. Oxygen systems will be optimally
effective if they are planned as part of an overall approach to improve quality of care
within a hospital and a ward. A team approach is necessary, involving clinical staff,
hospital administrators, engineers and trainers. Choosing the location, establishing
a high-dependency area that is integrated within the ward and ensuring that there is
sufficient technical expertise for day-to-day care, regular maintenance and safety of
equipment are all crucial to increasing the availability of oxygen and having a positive
impact on patient outcomes.


The following section outlines the key steps and considerations required in the
procurement process to guide the selection of appropriate high-quality concentrators.
An overview of existing manufacturers and models of stationary oxygen concentrators
and their specifications are listed in Annex 2. These existing devices (June 2015) have
FDA clearance and/or a Declaration of Conformity to ISO 8359 (refer to Section 5.5 for
essential information regarding selection of appropriate concentrators).


This document draws upon certain aspects of the procurement process outlined in
the Procurement capacity toolkit: tools and resources for procurement of reproductive
health supplies, which was published by PATH in 2009 (39), and from The TCu380A
intrauterine contraceptive device (IUD): specification, prequalification and guidelines
for procurement, which was published by WHO in 2010 (40).


Additional information on WHO guidelines for procurement is available at http://
whqlibdoc.who.int/publications/2011/9789241501378_eng.pdf?ua=1. Procurement
guidance specific to medical devices is available at http://www.who.int/medical_devices/
management_use/en.


5.1 Needs assessment


Prior to procurement, an oxygen needs assessment must be performed to identify
the appropriate equipment for a particular ward or hospital and to define the power
supply requirements. Assessing and defining power supply requirements for oxygen
concentrator devices and related equipment will depend on several factors that should
be discussed with all parties involved in the usage, procurement and distribution
of oxygen concentrator devices. For additional procurement guidance, including
information on conducting needs assessments, refer to Needs assessment for medical
devices at http://www.who.int/medical_devices/management_use/en (41).


5.1.1 Define programme context
Before forecasting and quantifying product requirements, it is important to understand
the needs of the end users and the country policies and guidelines. Country policies
and guidelines will determine the appropriate clinical applications for oxygen therapy,
placement within the health system and appropriate personnel to be trained and


Technical specifications for oxygen concentrators 34




approved to use oxygen concentrator devices. The top priority usually lies in providing
oxygen to sick neonates and young children. Availability of funds is the usual limiting
factor to providing oxygen to other areas.


5.1.2 Forecast programme requirements
Before the procurement process can begin, it is important to forecast the requirements of
each type of device. Conducting an oxygen needs assessment is essential to determine
the number of oxygen concentrators that should be available. This number depends on
the total number of beds, the number of annual admissions, the estimated proportion
of patients admitted who have hypoxaemia, the average duration of hypoxaemia and
the need to accommodate higher hypoxaemic admissions in the peak season(s). These
data are not always available and do not address other system and capacity factors that
can affect utilization. A short audit to assess the current situation, including using pulse
oximetry to assess the prevalence of hypoxaemia and/or reviewing basic admission data
for children, may be necessary.


As a rough guide, oxygen concentrators are often used in neonatal units, paediatric
wards and operating theatres. If needed in these areas, at least one concentrator per
room is recommended to prevent removal. At a minimum, planning should be done
to ensure that oxygen is available for all critical unit beds in the neonatal wards and
for a sufficient percentage of beds in the paediatric wards. In hospitals where acute
respiratory infection is the most common condition, it has been found that 9–38% of
admitted children with pneumonia will have hypoxaemia (42). The average duration of
hypoxaemia in children with pneumonia is about two–three days, although some studies,
particularly in hospitals at higher altitudes, have found an average duration of up to five
days (29,43,44). A sample equipment list is provided in Table 4. These quantities must
be adjusted based on the oxygen needs assessment as appropriate.


5.1.3 Customize the specifications
One of the more important responsibilities of a purchaser is to ensure that each oxygen
concentrator device specification is accurate, detailed, clear and consistent. The
purchaser should review the WHO specifications in this guide to fully understand the
different levels of requirements and to identify which requirements can be adapted by
the purchaser to address specific programme needs and which requirements must be
left unaltered so as not to jeopardize the integrity and quality of the product. See Annex 1
for an overview of procurement specifications, Section 2.2 for the minimum specification
requirements and Section 2.3 for guidance on customizing the specifications.


5.2 Programme planning


It is important to note the minimum resources that should be available when considering
the implementation of oxygen concentrators:


• pulse oximetry;
• capacity for technically trained staff;
• source of reliable power;
• availability of consumables, spare parts and maintenance tools;
• physical space to place the concentrator (see Section 4.2).


35Technical specifications for oxygen concentrators




At a minimum, the following should be included as part of an oxygen concentrator
procurement plan:


• oxygen concentrators that can deliver a continuous flow of concentrated oxygen
(>82%);


• reusable pulse oximeter with a guaranteed supply of sensor probes – it is
recommended that a five-year supply be considered;


• adequate yearly supply of appropriate patient delivery consumables and accessories
– it is recommended that a five-year supply be considered;


• availability of spare concentrators and back-up supplies (e.g. back-up power
supplies and oxygen cylinders) in case of power failure.


5.3 Procurement planning


Prior to procuring oxygen concentrators, it is important to establish a procurement plan
that includes the following:


• Confirmation of budget allocations and timing for the availability of funds.
• Technical specification review ensuring the following (see Annex 1):


› the general performance and design description is complete;
› regulatory requirements are clearly stated;
› packing, labelling and marking requirements are included;
› sampling, inspection and testing protocols are included where necessary.


• Confirmation of the required delivery date, location and mode of transport.
• Knowledge of specific country requirements and national regulatory procedures


that need to be taken into account; e.g. many countries have special regulations
covering the importation of medical devices. Procurers involved in the procurement
of oxygen concentrator devices need to be aware of any rules and regulations.
Questions concerning specific requirements that should be answered include:
› Is there a mandatory national quality standard with which the oxygen concentrator


devices must comply?
› How are the standards applied?
› What other requirements are there, such as import taxes and duties, certification,


required shipping documents?
› Is there a requirement for registration prior to importation?
› Is there an in-country requirement for confirmatory testing and/or pre-inspection


(physical and/or shipping documents)?


Information can be obtained from the national regulatory authority and/or the Bureau
of Standards of each country.


5.4 Assessment of procurement options and procurement method


In preparing for the procurement of oxygen concentrators, the purchaser must determine
which procurement method would be most appropriate for the particular circumstances
of the country and the programme needs.


The process of assessing the options for procurement is intended to:
• identify the procurement options that are possible;
• consider what is practical under the circumstances;


Technical specifications for oxygen concentrators 36




• look at who can/will do the work;
• examine cost implications;
• evaluate the options and select the most appropriate option or procurement method


for the procurement.


There are a number of options for obtaining oxygen concentrators for LRS, depending
on the agreements made in low-income countries. Options include:


• direct from manufacturers depending on country programme and needs;
• government agencies; e.g. the United Nations Children’s Fund (UNICEF) Supply


Division, the United Nations Population Fund (UNFPA) or the United Nations Office
for Project Services (UNOPS);


• international procurement agents such as those approved by national governments;
• manufacturer-approved distributors may also exist for some products (contact the


manufacturer to obtain information on an authorized distributor in the region where
the products are being procured);


• rental contracts that are sometimes available from third-party distributors;
• donations.


Product offerings and catalogues offered through government agencies or approved
international procurement agents are intended to assist in the planning, procurement,
supply and/or delivery of essential commodities. An understanding of all the available
procurement options for oxygen concentrators is critical for selecting a procurement
method that is suitable and economically feasible for the destination country.


5.5 Manufacturers and warranties


There are many oxygen concentrators on the market, but not all are of high quality or
appropriate for effective use in LRS. Independent testing of seven 5 LPM concentrators
found that most concentrators did not meet the manufacturer’s specifications (22).
From this study, operation at simultaneous high temperature and RH was a common
problem. Therefore, independent verification of a device’s performance under the
maximum specified temperature and RH is ideal.


Overall, the manufacturer and model of concentrators should be selected based on the
specifications outlined in Section 2.2, contexts of use outlined in Section 2.3 and the
documentation outlined in Section 5.7. Current models of concentrators (June 2015)
comply with ISO 8359. An overview of manufacturers, current models with clearance
from the FDA and/or CE conformity to ISO 8359 and their performance specifications
are listed in Annex 2. Future devices will be expected to comply with ISO 80601-2-
69:2014 (which supersedes ISO 8359) following ratification.


Because new models of oxygen concentrators appear every year, consistently
procuring concentrators from one or two manufacturers is critical to the bidding and
procurement process to help ensure continuation of services and uniformity of spare
parts, maintenance and training. A country may or may not have special requirements
or registration processes for medical devices. Regardless, it is important to select
manufacturers and devices that fit quality assurance needs and requirements.


37Technical specifications for oxygen concentrators




Warranties should always be requested during the procurement process, and service
contracts are usually established after the warranty expires. The original manufacturer
and/or a third-party provider may offer additional warranties and service contracts.


It is important to clearly understand what the contract includes, such as cost,
transportation, services and replacement components. Additionally, it is essential to
identify who will perform the installation, training, repair and maintenance. Ideally, the
manufacturer and/or the service provider should be responsible for providing technical
support, regular maintenance and repair for the duration of the warranty. The procurer
defines the time of the warranty. It is recommended that the warranty should be at least
two years, and longer if possible, with a prepaid service contract that ensures that the
equipment will be available and operating for several years after acquisition.


It is important to have an understanding of what is already in good working order in
health facilities as well as an estimate of each device’s average lifespan. While there is
no standard method for reporting lifespan, the useful life of oxygen concentrators can
reasonably span several years with proper maintenance and repair (see Section 4.6).
The compressor is subject to the most wear, but can be repaired or replaced if available
from the manufacturer. Many the manufacturers quantify the lifetime of components as
hours under normal conditions of use (i.e. with regular cleaning, dust-free environment
and reliable power). As a guide, one year of use ranges from 5000 hours (moderate
use) to 8000 hours (nearly continuous use year round). Expected lifetimes may differ
between manufacturers and will decrease if the equipment is poorly maintained and/
or in hot, dusty and sooty environments.


Warranty options are not always possible, such as when equipment is donated or the
cost and time required to return equipment to the manufacturer are beyond capacity.
In such cases, a system and budget for maintenance and repair would need to be set
up independently (3,38). This requires training of local engineering departments and
setting up a spare-parts inventory, which should form part of the donation. Contact with
the original manufacturer is required to determine if the following services are provided:
continuing technical support; troubleshooting assistance; recommendations to maintain
spare-parts inventories pertaining to those particular models that are donated; and
technical training either at their facility or onsite.


5.6 Safety standards and regulatory approvals


Oxygen concentrators are medical devices, and many countries have special regulations
covering the importation and distribution of medical devices. Most national regulatory
authorities require that a product comply with appropriate international or national
standards before it can be marketed. These standards establish minimum safety,
performance and quality requirements for a wide range of products, including oxygen
concentrators. The principal international standards authority is the ISO, the worldwide
federation of national standards bodies.


Oxygen concentrators that meet minimum specifications for quality and safety must
comply with the ISO standards for oxygen concentrators and IEC 60601-1 (current
version edition 3.1 2012-08) or their equivalent. The current ISO standard for existing


Technical specifications for oxygen concentrators 38




oxygen concentrators, as of June 2015, is ISO 8359. Future concentrators will be
expected to comply with ISO 80601-2-69:2014 following ratification (note that these
are not expected to enter the market until 2017 or later).


ISO has also created ISO 13485, a standard for ensuring high-quality manufacturing of
medical devices. ISO 13485 prescribes the documentation, procedures and structures
to follow to facilitate the production of devices of consistent quality and standards.
Manufacturers must demonstrate compliance with ISO 13485, or equivalent good
manufacturing practices.


ISO standards are updated from time to time and current editions can be purchased
from national standards organizations or directly from ISO at http://www.iso.org/iso/
home.htm. Direct ISO certification is typically conducted by third-party services and
documentation of compliance can be requested from the manufacturer. It is important
to request the most current documentation of compliance as well as all necessary
regulatory approval(s) for countries for which oxygen concentrators will be procured
and distributed (see below for further information).


Oxygen concentrators fall under the purview of various regulatory authorities that license
drugs and medical devices for use in a particular country or region. However, regulatory
authorities depend on the stated specifications from manufacturers and may not require
independent testing protocols to verify the quality of the oxygen concentrator before
they are shipped to the country.


Two well-established regulatory procedures for oxygen concentrators are the FDA 510(k)
pre-market clearance procedure and the European Union (EU) CE marking scheme.


In the United States, oxygen concentrators are regulated as Class II medical devices.
To receive clearance for sale of a Class II medical device in the United States, a
manufacturer must submit a 510(k) pre-market notification to the FDA with information
demonstrating device safety and effectiveness. The 510(k) process requires that the
manufacturer demonstrate equivalence to a predicate device, which would be an oxygen
concentrator that has already received 510(k) market clearance.


In the EU, oxygen concentrators are regulated as Class IIa, according to classification
Rule 11 of the European Medical Device Directive (93/42/EEC as amended). Prior to sale
in the European market, a manufacturer of a Class IIa device must obtain certification
from an EU-accredited Notified Body, which assesses conformity to the Medical Device
Directive of the manufacturer’s technical file and quality system. After the Notified Body
validates conformance, the manufacturer affixes the CE mark to the device and issues
a Declaration of Conformity.


If devices that are not approved in the United States or EU are used, they should have an
equivalent internationally recognized regulatory approval, such as those from members
of the IMDRF. The IMDRF includes Australia, Brazil, Canada, China, the EU, Japan,
the Russian Federation and the United States. Most countries have their own regulatory
procedures, which should cite published standards. The regulatory process for medical
devices in countries outside the United States and EU must conform to equivalent
quality management systems: US 21 CFR part 820 Quality System Regulation; EU


39Technical specifications for oxygen concentrators




Medical Device Directive 93/42/EEC; and ISO 13485:2003 Medical devices – Quality
management systems – Requirements for regulatory purposes.


5.7 Documentation


The following relevant documentation can be requested to help ensure high-quality
oxygen concentrators:


• ISO certificates;
• letter of FDA clearance, Declaration of Conformity for the CE mark or other regulatory


body approval documentation;
• certificate of registration in the country to be shipped or import waiver, if applicable;
• documentation showing conformance with the manufacturer’s performance


specification for oxygen concentration at maximum flow and simultaneous maximum
operating temperature and maximum RH (see Section 2.2).


Documentation of conformance with the ISO standard for oxygen concentrators and
necessary regulatory approval(s) should always be requested from the manufacturer
(see Section 5.6).


Other information that may be important to request in a tender/request for quotation
includes:


• lead time from receipt of contract/purchase order;
• delivery date;
• method of shipment;
• shipping route;
• freight and insurance costs;
• International Commercial Terms (Incoterms®) ensure that it is clear who is paying


customs clearance charges, import duties and taxes, final delivery costs, etc.;
• shipment/delivery costs;
• handling fees;
• warranty information, if applicable;
• service contract information, if applicable;
• training information, if applicable;
• weights and dimensions of shipment (of particular importance if procurement is


done on an ex works basis and this information is needed for a freight forwarder or
shipping line/airline to provide a freight quotation);


• validity of quotation;
• payment terms;
• general and any special terms and conditions that will appear on the contract and/


or the purchase order.


5.8 Manufacturer user and maintenance manuals


User and service manuals are indispensable sources of information for installation,
maintenance and training purposes. Electronic and/or paper copies should always be
supplied and:


• available in English, French and Spanish (ideally in the local language);


Technical specifications for oxygen concentrators 40




• provide instructions for cleaning and use;
• provide instructions for all preventive maintenance and replacement procedures;
• include the contact information of the manufacturer and/or the local supplier;
• detail all spare or replacement parts, their expected lifetime under normal use and


costs, ideally for five years of use;
• include a troubleshooting guide (see example in Table 3);
• some manufacturers may have useful instructional videos available online.


5.9 Consumables and spare parts


A system to replenish consumables and maintain an inventory of spare parts is
essential, as concentrators are likely to fail prematurely without regular maintenance
and replacement parts. Furthermore, replacement parts can be in scarce supply and
a supply and maintenance infrastructure is rarely in place, which results in device
underutilization or failure. Therefore, it is important that a continuous supply of
consumables and replacement parts is identified and arranged at the time of initial
purchase since oxygen concentrators are unsustainable without the regular procurement
of spare parts. It is recommended that a minimum five-year supply be considered.
Consumables and spare parts must be continually sourced from the manufacturer, as
local suppliers may not have these supplies.


The primary consumables and spare parts include the patient delivery accessories, such
as nasal prongs and catheters and gross particle filters. Note that gross particle filters
may also be referred to as air (intake) filters, or coarse filters (see Table 2). Filters must
be regularly cleaned and users should follow the appropriate clinical or manufacturer
guidelines on cleaning and replacement (see Sections 4.4 and 4.5). Procurers should
purchase an initial set of replacements for at least one year of use (ideally five) in the
initial purchase contract.


While oxygen demand varies between hospitals and regions, a rough guide to the
amount of consumables, supporting equipment and spare parts needed is provided in
Table 4. Detailed studies conducted in LRS regarding oxygen concentrator spare parts
replacement frequency and cost are described in the literature (3,38).


The inventory of spare parts should contain components that wear out quickly and most,
if not all, electrical components. Items to consider include compressors, compressor
mounts, sieve beds, valves, printed circuit boards (PCBs), on/off power switches, power
cords, hour meters, circuit breakers, fuses, motor capacitors, fans, tubing, fittings
and wheels. This inventory of parts should be adjusted according to the number of
concentrators being supported.


41Technical specifications for oxygen concentrators




Table 4. Sample equipment list for the administration of oxygen for up to two paediatric patients from one
oxygen concentrator; adjust per oxygen needs assessment, manufacturer specifications and device model


Equipment
Minimum quantity


for use
Example quantity


for one yeara
Example quantity


for five yearsa,b


Oxygen concentrator


Oxygen concentrator, 5 LPM 1 1 1


Gross particle filter Varies 3 15


Intake, product filters Varies 1 each 5 each


Circuit breaker, PCB, sieve beds,
compressor, valves, fans, service
kits


Varies As needed As neededb


Oxygen delivery devices


Kink-resistant plastic oxygen
delivery tubing, up to 15 m each 2 12 60


Oxygen outlet adaptor(s), if
applicable 1 3 15


Nasal prongs 2 x each size 26 x each size 130 x each size


Four-way flow splitter or
flowmeter stand 1 1 1


Nozzles of 0.5, 1 and 2 LPM, if
using flow splitter 4 each 4 each 8 each


Blanking plugs, if using flow
splitter 4 4 8


Other equipment


Pulse oximeterc 1 1 1


Pulse oximeter probes 2 x each size 2 x each size 4 x each size


Back-up cylinder with regulator
and flow controller 1


Depends on power
availability


Depends on power
availability


Surge protector 1 1 1


Firebreak device 1 1 1


Voltage stabilizer, if applicable 1 1 1


LPM, litre(s) per minute; PCB, printed circuit board
a Assuming regular use, one set of spares (if lost or broken) and one set for replacement (once per month for breathing apparatuses, once every two months for oxygen tubing,


once per year for oxygen adaptors, and once every five years for nozzles, blanking plugs, and pulse oximeter probes).
b See study by Bradley et al. (2015) for additional information (38).
c One pulse oximeter is desirable per patient, but a single one may be used to spot-check each patient throughout treatment.
Source: Adapted and republished with permission of Maney Publishing, from Duke et al. (2010) (7); permission conveyed through Copyright Clearance Center, Inc.


Technical specifications for oxygen concentrators 42




6. Areas for future research


Technical specifications play a vital role in the selection, procurement and implementation
of affordable and high-quality oxygen concentrator supply systems. In the development
of this guidance, several technology and knowledge gaps were identified. Stakeholder
collaboration to address these gaps may help to improve the availability and sustainability
of oxygen supply systems in LRS.


Increase availability of affordable and cost-saving accessories and devices:
• Flowmeter stands allow multiple paediatric patients to be treated with one machine.


Current flowmeter stands are difficult to find and cost nearly the same as the
concentrator.


• Devices with dual outlets, higher oxygen outlet pressure and nebulizing functions
are valuable in neonatal and paediatric wards, and some devices currently have
this feature (but publications regarding their performance in LRS have not yet been
found).


• Some device features that may be useful to end users and purchasers may not
be readily specified in manufacturer specification sheets. This includes stating
whether the device has flow limiters to prevent the user from overdrawing oxygen
and damaging the devices.


Establish international standards and clinical guidelines for life-saving essential health
technologies, some of which may expand the use of oxygen concentrators:


• There is a lack of technical specifications for pulse oximeters and sensor probes
appropriate for LRS. Recent research evaluating their quality and affordability must
also be taken into consideration.


• No comprehensive clinical guidelines currently exist for the sizes of patient delivery
consumables and accessories. The absence of internationally agreed standard sizes
may leave room for confusion during procurement.


• There is a lack of clinical guidelines for bubble CPAP, a life-saving treatment for
infants for which an oxygen concentrator could be easily repurposed. This is an
evolving field; more evidence-based literature is needed to support the development
of technical specifications on the use of oxygen concentrators for this application.


Develop unbiased optimal recommendations without sacrificing affordability, quality and
availability:


• While current oxygen concentrators are suitable for implementation in most health
facilities in LRS, further design improvements to reduce the burden of maintenance
on clinical staff would be highly valued. More data are needed concerning the
reliability and sustainability of both older and new models, such as those that comply
with either ISO 8359 or ISO 80601-1-2:2014.


• While a system of procuring spare parts may seem costly, but necessary; a
retrospective analysis of oxygen concentrator needs and costs in Gambia showed
that most repairs within a seven-year period were low cost and required a low
level of technical experience to complete. More studies such as this are needed
to demonstrate the cost-effectiveness and simplicity of oxygen concentrator-based
systems.


43Technical specifications for oxygen concentrators




• Many current oxygen concentrators lack features that could increase the usability
and/or utility in LRS. These features include the ability to operate at below 0 °C
or above 40 °C, larger diameter wheels and decals affixed to a unit that illustrate
minimum user operation instructions.


Improve research and knowledge-sharing on life-saving essential health technologies:
• There is limited knowledge of the power quality among the different health systems


in developing countries. Quantitative information on voltage fluctuations could
help inform procurement needs and specification development for manufacturers
and standards organizations to produce oxygen concentrators and other electrical
medical devices better suited for these countries.


• There is limited evidence-based research on the widespread clinical and economic
impact of oxygen concentrators and oxygen therapy in LRS. More studies are
necessary to improve awareness, increase procurement efficiency and motivate
stakeholders to prioritize oxygen availability in LRS.


Technical specifications for oxygen concentrators 44




Annex 1 Oxygen concentrator technical
specifications


Table A1.1 summarizes technical specifications to guide the procurement and
acquisition of oxygen concentrators of high quality, safety and efficacy as well as
other considerations for implementation, functioning and decommissioning. Similar
specification sheets for other critical medical devices are available from the World
Health Organization (WHO). The template used to produce this table was developed
by WHO and can be found at http://www.who.int/medical_devices/management_use/
mde_tech_spec/en.


Table A1.1 Oxygen concentrator technical specifications


Medical device specification
(where relevant/appropriate, including information on but not limited to the following)


i Version number


ii Date of initial version 2012


iii Date of last modification June 2015
iv Date of publication September 2015


v Completed/submitted by WHO, PATH


Name, category and coding


1 WHO category/code


2 Generic name Oxygen concentrator.


3 Specific type or variation (optional) Stationary oxygen concentrator.


4 GMDN term name Stationary oxygen concentrator.


5 GMDN code 12873


6 GMDN category 02 Anaesthetic and respiratory devices, 04 Electro mechanical medical devices, 11 Assistive products for persons with disability.
7 UMDNS™ name Oxygen concentrators.


8 UMDNS™ code 12873


9 UNSPSC® code (optional) 42271702


10 Alternative name/s (optional) Concentrator, oxygen concentrator, oxygen enricher, stationary concentrator, bedside concentrator.


11 Alternative code/s (optional) CAW (FDA)


12 Keywords (optional) Hypoxaemia, oxygen therapy.


13 GMDN/UMDNS™ definition (optional)


A stationary mains electricity (AC-powered) device designed to concentrate oxygen from ambient air
and deliver the concentrated oxygen, typically through an attached nasal cannula (or prongs), to a
patient requiring oxygen therapy. It processes the air through an internal filtration system (e.g. a
molecular sieve [zeolite granules or membranes]), which has a large total surface area to separate N2
from the air. It typically consists of an air compressor, filters, dual chambers, a reservoir and controls.
The oxygen concentration is variable depending on the flow rate utilized. It is typically wheeled, but is
designed to be placed in one location (e.g. an institution or a home setting).


45Technical specifications for oxygen concentrators




Purpose of use


14 Clinical or other purpose
Delivery of low-flow, continuous, clean and concentrated oxygen (>82%) from room air
(21%). With appropriate accessories, two or more hypoxaemic patients can be treated with one
concentrator.


15 Level of use (if relevant) Health centre, general hospital, district hospital, provincial hospital, regional hospital, specialized hospital.


16 Clinical department/ward (if relevant) Paediatric ward, surgical operating theatre.


17 Overview of functional requirements


1. Provides a continuous flow of concentrated oxygen (>82%) from room air through one or two
oxygen outlets.
2. Contains oxygen monitor to verify concentration.
3. Delivers oxygen through a nasal prongs or nasal catheter.
4. Flow from one concentrator can be divided for at least two paediatric patients with (built-in or
add-on) flowmeters that allow continuous flow rate control.
5. Requires continuous AC power source to operate, such as solar power, battery or mains
electricity ± backup (e.g. generator, UPS or battery).
(Maximum flow is chosen based on the expected patient load at any given time. Oxygen needs
vary per by patient and application. In general, up to 2 LPM per patient under 5 years of age is
needed.)


Technical characteristics


18 Detailed requirements


1. One or two oxygen outlets.
2. Audible and/or visual alarms for low oxygen concentration (<82%), low battery and power
supply failure.
3. Audible and/or visual alarms for high temperature, low/high/no-flow rate and/or low/high
pressure.
4. Power efficiency <70 W/LPM.
5. User interface to be easy to operate; numbers and displays to be clearly visible.
6. Digital or analogue meter that displays cumulative hours of device operation.
7. Oxygen outlet(s) with 6 mm (¼-inch) barbed fitting, or equivalent.
8. Flowmeter minimum flow rate of 0.5 LPM or less.
9. Flowmeter continuously adjustable, with minimum markings at 0.5 LPM intervals (or lower for
paediatrics).
10. Oxygen monitor for signalling when concentration is below 82%.
11. Noise level <50 dB(A).


19 Displayed parameters Oxygen flow rate (on flowmeter).Cumulative hours of operation.


20 User adjustable settings Oxygen flow rate.


Physical/chemical characteristics


21 Components (if relevant)
Case to be hard, easy to wipe clean and safe to transport.
Oxygen outlet to be not easily broken or bent.
Contains flow limiter to prevent overdrawing oxygen flow beyond rated maximum flow rate.


22 Mobility, portability (if relevant)
Whole unit to be easily movable by a single person (<27 kg).
Castor wheels.


23 Raw materials (if relevant)
Water, detergent and/or mild cleaning solution to clean device exterior and gross particle filter (if
applicable).


Utility requirements


24 Electrical, water and/or gas supply (if relevant)


Electrical source requirements: Amperage: ______; Voltage: ______; Plug type: ______
(based on country/setting of use).
Voltage corrector/stabilizer to allow operation at ± 20% of local rated voltage.
Protections against overvoltage and overcurrent line conditions.
Electrical protection by resettable circuit breakers or replaceable fuses, fitted in both neutral and
live lines.
Compliance with _______ electrical standards and regulations.
Surge protector.


Accessories, consumables, spare parts, other components


25 Accessories (if relevant)


For two or more simultaneous paediatric patients:
• 1 x flowmeter stand with minimum range from 0 to 2 LPM; or
• 1 x four-way flow splitter with 0.5, 1, 2 LPM nozzles and blanking plugs.


Kink-resistant oxygen tubing with standard connectors (15 m each).


Technical specifications for oxygen concentrators 46




26 Sterilization process for accessories (if relevant) Disinfection for nasal prongs.


27 Consumables/reagents (if relevant)


Five-year supply recommended.
One-year supply (adjust quantities per patient load and usage frequency):


• nasal prongs or nasal catheters (each size for adult, child, infant);
• child nasal prongs: distal diameter: 1–2 mm:


› child/infant catheters: 6 or 8 French gauge.


28 Spare parts (if relevant)


Five-year supply recommended.
One-year supply (adjust quantities per manufacturer specifications and model design):


• 3 x gross particle filters
• 1 x intake filters
• 1 x product filters
• 3 x oxygen outlet connectors
• blanking plugs and nozzles, if using flow-splitter.


Other spares that may be needed: circuit breaker, printed circuit board, sieve beds, compressor
service kit, valves, wheels, motor capacitor, flowmeters and fan.
(Spare parts are not interchangeable between devices of different brands and models, and can
vary in their design and lifetime. Medical units to select spare parts ensuring compatibility with the
brand and model of the equipment.)


29 Other components (if relevant) NA


Packaging


30 Sterility status on delivery (if relevant) NA


31 Shelf life (if relevant) NA


32 Transportation and storage (if relevant)
Keep away from oil, grease and petroleum-based or flammable products as well as smoking or
open flames.


33 Labelling (if relevant) Electrical power input requirements (voltage, frequency and socket type).


Environmental requirements


34 Context-dependent requirements


Capable of being stored continuously in ambient temperature from 0 °C to 40 °C, RH from 15% to
95% and elevation from 0 to 2000 m.
Capable of operating continuously in ambient temperature from 10 to 40 °C, RH from 15% to
95%, simultaneously, and elevation from 0 to 2000 m.
(For operation at elevations higher than 2000 m, environmental requirements may be less
stringent due to milder conditions.)


Training, installation and utilization


35
Pre-installation
requirements
(if relevant)


Verify plug electrical requirements with socket to be used.
Clinical and staff training on device use.
System for procuring spare parts.


36
Requirements for
commissioning
(if relevant)


Note and report any signs of external or internal damage upon device delivery.
Record the number of hours on the hour meter.
Verify oxygen concentration level is within specifications when device is operated with all tubing
and flowmeters installed.
Verify operation of oxygen concentration, battery and power failure alarms.
Spare parts for one year or 5000 hours (five years or 15 000 hours ideally) of use are arranged.


37 Training of user/s (if relevant)


Clinical staff training in oxygen therapy guidelines, device use and multiple-patient use.
Technical staff training in device operation, safety and maintenance provided by manufacturer,
supplier or experienced users.
Advanced maintenance tasks required shall be documented.


38 User care (if relevant)


Device exterior to be wiped effectively with a mild solution of detergent or cleaning agent
(weekly), without connection to mains power.
Gross particle filter to be cleaned effectively when removed and washed with soap and water (weekly).
Do not clean with alcohol.
(User care needed more often in very dusty environments.)


Warranty and maintenance


39 Warranty


Two years or more (five years ideally) to cover lifespan of equipment.
Manufacturer/supplier ideally responsible for all costs for repairs and replacement covered under
the warranty.
Extended warranty options specified by manufacturer.


47Technical specifications for oxygen concentrators




40 Maintenance tasks


Test power failure alarms.
Measure operating pressure with pressure test gauge.
Measure oxygen concentration with a calibrated oxygen analyser.
Repair internal components as needed.
Maintain spare-parts inventory.


41 Type of service contract
Service contract is recommended and includes technical support, spare parts, maintenance and
repairs.
Pricing for service contracts should be negotiated before the system is purchased.


42 Spare parts availability post-warranty
Less than four weeks after warranty end. Five years of spare parts should be organized at the time
of purchase and replaced when used.


43 Software/hardware upgrade availability NA


Documentation


44 Documentation requirements


User, technical and maintenance manuals to be supplied in ______ language.
Procedures for cleaning and disinfection/sterilization.
Contact details of manufacturer, supplier and local service agent.
List of all spare or replacement parts, their lifetime and costs for five years of operation.
Troubleshooting guide.


Decommissioning


45 Estimated lifespan Seven years; this can vary between brands.


Safety and standards


46 Risk classification Class C (GHTF Rule 11); FDA Class II (USA); Class IIA (EU and Australia); Class II (Canada).


47 Regulatory clearance/certification CE mark (EU); FDA 510k clearance (USA).


48 International standards


ISO 80601-2-69:2014 Medical electrical equipment – Part 2–69: Particular requirements for basic
safety and essential performance of oxygen concentrator equipment.
IEC 60601-1:2012 Medical electrical equipment – Part 1: General requirements for basic safety
and essential performance.
IEC 60601-1-2:2014 Medical electrical equipment – Part 1–2: General requirements for
basic safety and essential performance – Collateral Standard: Electromagnetic disturbances –
Requirements and tests.
IEC 60601-1-6:2013 Medical electrical equipment – Part 1–6: General requirements for basic
safety and essential performance – Collateral standard: Usability.
IEC 60601-1-8:2012 Medical electrical equipment – Part 1–8: General requirements for basic
safety and essential performance – Collateral Standard: General requirements, tests and
guidance for alarm systems in medical electrical equipment and medical electrical systems.
IEC 60601-1-9:2013 Medical electrical equipment – Part 1–9: General requirements for basic
safety and essential performance – Collateral Standard: Requirements for environmentally
conscious design.
IEC 60601-1-11:2010 Medical electrical equipment – Part 1–11: General requirements for basic
safety and essential performance – Collateral Standard: Requirements for medical electrical
equipment and medical electrical systems used in the home health-care environment.
ISO 13485:2003 Medical devices – Quality management systems – Requirements for regulatory
purposes (Australia, Canada and EU).
ISO 14971:2007 Medical devices – Application of risk management to medical devices.


49 Regional/local standards NA


50 Regulations


US regulations:
21 CFR part 820 Quality System Regulation.
21 CFR section 868.5440 Portable oxygen generator.
Japan regulations:
MHLW Ministerial Ordinance No.169 Standards for Manufacturing Control and Quality Control for
Medical Devices and In-Vitro Diagnostic Reagents.
EU regulations:
Medical Device Directive 93/42/EEC.


AC, alternating current; CE, Conformité Européenne/European Conformity; CFR, Code of Federal Regulations; dB(A), decibel(s) attenuated; EU, European Union; FDA, United States
Food and Drug Administration; GHTF, Global Harmonization Task Force; GMDN, Global Medical Device Nomenclature; IEC, International Electrotechnical Commission; ISO, International
Organization for Standardization; kg, kilogram(s); LPM, litre(s) per minute; m, metre(s); mm, millimetre(s); N2, nitrogen; NA, not applicable; RH, relative humidity; UMDNS, Universal
Medical Device Nomenclature System; UNSPSC, United Nations Standard Products and Services Code; UPS, uninterruptible power supply; US or USA, United States of America; W,
watt(s); WHO, World Health Organization


Technical specifications for oxygen concentrators 48




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Technical specifications for oxygen concentrators 50




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51Technical specifications for oxygen concentrators




Annex 3 Sample calculation of back-up
energy requirement for an oxygen
concentrator


Variable Notes Example value


Concentrator power consumption (A) 100–600 W, depending on the model 400 W


Average duration of power outage per
day (B) Varies from facility to facility 4 hours


Additional compensation for losses (C) Batteries will lose capacity and require replacement over time 10%


Battery depth-of-discharge (D)


10–70% depending on the battery type;
batteries should not be depleted beyond
the rated depth-of-discharge, in order to
maintain the battery’s optimal lifetime


50%


Calculations


Total concentrator back-up energy
requirement per day (E) A x B x (1 + C/100)


400 W x 4 h x (1 + 0.1) = 1760 Wh =
1.76 kWh


Total back-up battery bank energy
requirements E x (100/D)


1760 Wh x (100/50) = 3520 Wh =
3.52 kWha


Ah, ampere hour; kWh, kilowatt hour; Wh, watt hour
a Note that batteries are generally rated by both their V and Ah. The total energy stored in a battery bank (in Wh) is equal to: total number of batteries x V x Ah.
For additional guidance and training on sustainable energy technology options, specifications, training and maintenance, see http://www.poweringhealth.org/index.php/topics/
technology/design-and-installation.


Technical specifications for oxygen concentrators 52




Annex 4 Glossary


Continuous flow: The most common method of delivering oxygen that uses a constant
flow rate. Flow can be divided as necessary to deliver gas to multiple patients. The other
flow type is pulsed-dose flow.


Filter, gross particle: Also known as cabinet, air intake or coarse filter. Filters large
particulates from entrained air. This filter is generally a foam mesh located at the air
inlet of the device for easy cleaning. It blocks the majority of dust from entering the
case, protecting the fan, heat exchanger and intake filter. It should be cleaned weekly
or more frequently depending on air quality and particle accumulation in the filter. Dirty
and blocked filters will reduce airflow throughout the device. These filters can deteriorate
over time and may require replacement after approximately 10 000 hours of use.


Filter, high-efficiency particulate arrestance (HEPA): This is a specification for air filters
that are rated to remove very fine particulates as well as bacteria from gas streams.
These types of filters are often used as product filters as well as intake filters.


Filter, intake: Also known as inlet, compressor or compressor intake filter. Protects the
compressor and valves from particulates in the air. It is generally a paper filter and is
replaced every one–two years depending on the environment, but also can be designed
to last the entire device lifetime. Dirty and blocked filters will reduce airflow into the
compressor.


Filter, product: Also known as bacteria, high-efficiency particulate arrestance (HEPA),
final, final stage or output filter. Removes particulates from the product gas.


Flowmeter: Maintains a specified and steady flow rate, usually measured in standard
litre(s) per minute (LPM). Most machines have one or two integrated flowmeters.


Intermittent flow: A method of delivering flow that is not continuous, but provided as
boluses of concentrated oxygen. In portable oxygen concentrators, the inhalation
pressure of the patient is monitored so that the boluses are delivered at the start of every
breath. For this reason, flow cannot be easily divided to multiple patients. Also known
as pulsatile or pulsed-dose flow.


International Organization for Standardization (ISO) standards: These standards require
manufacturers to disclose the performance of their devices, including specifications,
electromagnetic emissions and electrical immunity. Direct certification is done by third-
party services.


Oxygen concentrator, portable: A medical device that provides a continuous or pulsed-
dose flow of therapeutic oxygen.


Oxygen concentrator, stationary: A medical device that provides a continuous and clean
flow of therapeutic oxygen.


Pressure swing adsorption: Process by which oxygen concentrators generate concentrated
oxygen from room air.


53Technical specifications for oxygen concentrators




Annex 5 Research on access to oxygen
therapy in low-resource settings
(LRS) for the treatment of childhood
pneumonia


Hypoxaemia, or low blood oxygen saturation, is a common complication of pneumonia,
the leading infectious cause of morbidity and mortality among children under 5 years
of age (20). Although pneumonia affects children worldwide, hypoxaemia is much
more common in LRS than in wealthy regions, and hypoxaemia is a strong indicator of
pneumonia mortality (24). In 2013, pneumonia killed 935 000 children – about 2600
children every day – and accounted for more childhood deaths than HIV/AIDS, malaria
and tuberculosis combined (20).


Delivering oxygen for treatment of hypoxaemia in children with pneumonia is essential
(3,45). A systematic review of hospital admissions in developing regions from 2009
revealed that the average prevalence of hypoxaemia in children with pneumonia was
13.3% and ranged from 9.3% to 37.5% (42). In recognition of the critical role of oxygen
in child health care, the World Health Organization (WHO) currently is preparing the
Manual on clinical use of oxygen therapy in children (23) to complement current clinical
guidelines for child health care (16,46).


Management of hypoxaemia is also a critical component of WHO guidelines for neonatal
resuscitation (15), anaesthesia (14), emergency care (14,17), triage (18) and treatment
of other common medical conditions and illnesses affecting neonates, children and
adults in developing countries (5). In neonates, common conditions requiring oxygen
therapy include respiratory distress syndrome, birth asphyxia and transient tachypnoea.
Neonates affected by prematurity, sepsis, seizures or hypoglycaemia can be prone to
apnoea, leading to hypoxaemia (5). Oxygen therapy is most commonly needed for adults
with chronic obstructive pulmonary disease, acute asthma, pneumonia and trauma
(2). Meningitis and malaria are hypoxaemia-related diseases affecting all age groups.
Hypoxaemia occurs frequently in trauma and obstetric and perioperative emergencies
(14). The WHO Integrated management for emergency and essential surgical care
toolkit contains recommendations for the minimum standards for quality and safety of
emergency, surgical, trauma and obstetric care, and anaesthesia at first-referral level
health-care facilities (17).


Hypoxaemia can be easily treated with oxygen. Oxygen therapy for the treatment of
hypoxaemia involves the delivery of concentrated oxygen to the patient to stabilize blood
oxygen saturation levels to above 90%. Oxygen is typically provided from an oxygen
concentrator or oxygen cylinder, each providing an oxygen concentration of greater than
85% or near 100%, respectively. WHO clinical guidelines recommend the delivery of
oxygen to infants and children with hypoxic respiratory illness using flow rates up to
2.0 standard litres per minute (LPM) (16). It is important to note that guidelines for the
safe administration of oxygen differ, including required flow rate and concentration of
oxygen delivered, depending on the patient’s age and condition. Oxygen therapy for


Technical specifications for oxygen concentrators 54




other patient populations and medical conditions can require flow rates up to 10 LPM
(14). Newborns, particularly preterm infants, are prone to oxygen toxicity and thus require
less concentrated oxygen (15).


Oxygen is a cost-effective and essential medicine included in the WHO Model list of
essential medicines for children (47). A prospective study across five hospitals in Papua
New Guinea observed a 35% reduction in the risk of child mortality from pneumonia
27 months after oxygen concentrators and a monitoring system were implemented
(24,48). The Child Lung Health Programme in Malawi installed oxygen concentrators in
all district hospitals more than a decade ago to support case management of childhood
pneumonia. The programme demonstrated a reduction in the case fatality rate of infants
and children with severe pneumonia (3,4,16).


Oxygen concentrators provide a good source of immediately available and cost-
effective oxygen, where oxygen cylinders and piped oxygen systems are inappropriate
or unavailable. First, oxygen concentrators have significant advantages in reliability
and cost over other oxygen supply systems (see Table 1). Analyses performed in Egypt
(13), Nepal (11), Nigeria (8) and Papua New Guinea (12) demonstrated the potential of
oxygen concentrators to expand the availability of oxygen in LRS. In Gambia, the cost
savings, as compared to use of oxygen cylinders, depended on oxygen demand and
power availability (4). The settings of these studies included areas that were remote,
high altitude or pertinent to paediatric wards.


Second, programmes in rural and district-level hospitals in Malawi and Papua
New Guinea have been successful in spite of high staff turnover (3,24,45,49). These
programmes have emphasized that robust training and maintenance systems are critical
to the success of oxygen concentrators. While these programmes were implemented
for childhood pneumonia, they can also provide the basis for implementation with other
common serious conditions requiring oxygen therapy, including trauma and obstetric
and perioperative emergencies (17).


Despite the evidence and existence of appropriate oxygen supply technologies, many
hypoxaemic patients in LRS still do not receive oxygen. Overall, oxygen is usually not
available in primary health clinics or smaller remote hospitals, and often is lacking in
district hospitals (1,21). Studies in Gambia, Malawi and Papua New Guinea showed
that oxygen supplies were poor and often unavailable for admitted children who were
hypoxaemic (2–4).


Even where oxygen supplies are available at a hospital, patient access may be limited
due to a lack of accessories, inadequate electricity and a shortage of trained staff. For
example, pulse oximeters and devices to connect the patient to the oxygen supply (e.g.
oxygen tubing, nasal cannulas or face masks) are often reported missing or underused
due to a lack of awareness and knowledge by staff (21,50,51). Oxygen supply is also
frequently interrupted due to shortages of mains power and the scarcity of fuel to run
back-up generators (50). It is not uncommon to find oxygen concentrators being moved
from paediatric wards to operating theatres or vice versa (52). As a result, it is not unusual
to encounter the following situations:


• oxygen supplies are available, but difficult to use because there are no accessories,
consumables or instructions;


55Technical specifications for oxygen concentrators




• oxygen devices are available, but broken because there are no maintenance staff
or replacement parts;


• oxygen is unavailable because demand and supply were unevenly matched, so
some patients are not given oxygen;


• oxygen is unavailable due to power outages and a lack of back-up power supplies;
• oxygen supplies are taken from paediatric wards or operating theatres.


As a result of oxygen shortages, patients often do not receive this critical therapy when
needed. There is a need to increase the availability of supplemental oxygen in LRS to
improve patient outcomes and survival.


Technical specifications for oxygen concentrators 56




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Technical specifications for oxygen concentrators 60




Notes
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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61Technical specifications for oxygen concentrators




Notes
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Technical specifications for oxygen concentrators 62






Essential Medicines and Health Products Department
Health Systems and Innovation Cluster
World Health Organization
20 Avenue Appia, 1211 Geneva 27, Switzerland
Tel +41 22 791 1239
E-mail: medicaldevices@who.int
http://www.who.int/medical_devices/en/


ISBN 978 92 4 150988 6




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