AN EVIDENCE-BASED APPROACH TO DEVELOPING A
TRAINING PROGRAMME FOR THE MAINTENANCE OF
OXYGEN CONCENTRATORS IN LOW-RESOURCE
B.D. Bradley*, Y-L. Cheng*, E. Nyassi **, D. Peel †, S.R.C. Howie ‡
*Centre for Global Engineering & Department of Chemical Engineering and Applied Chemistry, University of Toronto
**Biomedical Engineering Department, Medical Research Council Unit, The Gambia (Fajara, The Gambia)
†Ashdown Consultants (Hartfield, East Sussex, UK)
‡ Child Survival Theme, Medical Research Council Unit, The Gambia (Fajara, The Gambia)
Keywords: oxygen concentrator, maintenance, training,
biomedical technician assistant, clinical engineering,
developing countries, low-resource settings
Oxygen concentrators are an appropriate and low-cost
technology for supplying medical oxygen in low-resource
settings; however some maintenance and occasional repairs
are required to optimise their longevity. Through a skill-
mapping analysis based on historical concentrator repair logs,
we identified 31 basic technician skills that would be
sufficient for the repair of over 90% of observed oxygen
concentrator failures as well as for routine preventive
maintenance. Most of these skills are drawn from the library
of Biomedical Technician Assistant skills developed by the
Developing World Healthcare Technologies Lab and
Engineering World Health. We use this skill-mapping
analysis to propose an evidence-based training curriculum
specifically tailored to the maintenance of oxygen
concentrators in low-resource settings.
Research by Duke University’s Developing World Healthcare
Technologies (DHT) Lab in collaboration with Engineering
World Health (EWH) suggests that as much as 66% of out-of-
service medical equipment in developing countries can be put
back into service by providing technicians with skills-based
training in five key knowledge domains; plumbing, electrical,
mechanical, motors, and power supplies . Through an
analysis of thousands of medical equipment repair requests,
DHT and EWH developed a training curriculum for
biomedical technician assistants (BTA) centred around 113
skills that fall under these five key bodies of knowledge .
A skill is defined as “the steps required to diagnose and
execute a repair”, and can be taught to a secondary school
graduate in two hours . A library of these resources is
available online at: http://library.ewh.org , .
Oxygen concentrators are an appropriate and low-cost
technology for supplying medical oxygen in low-resource
settings -; however some maintenance and occasional
repairs are required to optimise their longevity. Concentrator
upkeep is a challenge in settings with inadequate resources
for maintenance .
In previous work, we analyzed almost 7 years of maintenance
and repair data for 27 oxygen concentrators managed by the
Biomedical Engineering Department at the Medical Research
Council (MRC) Unit in The Gambia, and determined
common failure modes, replacement parts needed, equipment
downtime, expected useful lifespan, and annual repair costs
(publication pending ). The dataset of 808 electronic
work orders from September 2006 to August 2013 consisted
of 142 inventory inspections, 33 repairs, and 633 preventive
maintenance checks (23 of which uncovered faults requiring
corrective action). The 33 repairs and 23 corrective
maintenance jobs were categorized by cause of failure (Table
1). The most common repairs were filter and check valve
replacements, and leakages or faulty tubing .
Categories of cause of failure Frequency
Filter needs replacement
Battery needs replacement
Faulty oxygen outlet
Leakage or faulty tubing
Pressure regulator needs adjustment
Electrical connection problems
Faulty sieve bed(s)
PCB problems or failure
Compressor problems or failure
Table 1: Frequency of different causes of failure for 27
oxygen concentrators (Sept 2006 to Aug 2013), as
previously reported in .
A mean of just over three preventive maintenance checks
were completed per machine per year. Preventive
maintenance involves testing the oxygen concentration,
cleaning the interior, checking batteries, and inspecting
internal filters. Over the 7-year analysis period, 85% of
concentrators experienced two or fewer repairs. Mean time to
the first failure was over two years. In any given year, about
30% of concentrators in service experienced a failure .
Based on this previous analysis, we hypothesize that a very
basic set of skills would be sufficient to repair the most
common causes of oxygen concentrator failure. The BTA
skill library developed by DHT and EWH offers a starting
point to test this hypothesis. In this paper we present the
results of a skill-mapping exercise that maps each reported
concentrator failure to the specific skills needed to complete
the repair. We also propose an outline with key topic areas
for an evidence-based training program for concentrators.
Lastly, we estimate the percentage of concentrator repairs that
could be resolved with this evidence-based training approach,
and note those repairs requiring a higher skill level or more
advanced knowledge that do not fall under this skills-based
Seven of the 56 reported repairs  were excluded from this
analysis; five had unknown or unrecorded causes of failure,
one failed beyond repair, and one was still unresolved at the
time of analysis. We mapped the remaining 49 repairs to
specific skills needed to resolve them, drawing upon the
DHT-EWH BTA skills library  where appropriate. For
example, the replacement of filters was one of the most
common repairs we observed, which is a skill under the
“Plumbing” knowledge domain. Additional skills not found
in this library were noted. We also identified the BTA skills
needed to perform routine preventive maintenance.
All MRC concentrators are from AirSep (Buffalo, NY) and
thus have uniform skill requirements. The skills needed for
some repairs could depend on the specific concentrator make
and model (e.g. type of clamp used for tubing). Based on our
knowledge of other makes and models we included a range of
related skills so that our analysis applies generally across all
3.1 Skill-Mapping Analysis
As shown in Table 2, 24 unique skills from the BTA skills
library were mapped to 49 oxygen concentrator repairs. The
number of times each skill was mapped to a repair is
indicated in parentheses.
Additional skills not found in the BTA library that we believe
were necessary for concentrator repairs are outlined in Table
3. One essential additional skill was pressure testing using a
pressure gauge (assuming the tool is available). Pressure tests
should be completed after any repair involving valves,
leakages, tubing, flowmeters or the pressure regulator. Most
concentrator models currently on the market are equipped
with an oxygen sensor and alarm that is triggered if the output
concentration drops below a certain threshold. In our
experience, this alarm only failed once (one of the
multicomponent failures), but it is important to be able to
repair this vital component. Sieve beds are a component
unique to oxygen concentrators that require special gripping
tools to remove. For printed circuit boards (PCB), we added
a skill for advanced PCB troubleshooting, but these failures
were rare in our experience (Table 1). In the analysis by
DHT , such advanced repairs were classified as “Other”.
With the exception of the advanced PCB skill, we believe the
additional skills in Table 3 are similar in difficulty level to
those in the BTA curriculum (i.e. could be taught to a
secondary school graduate in two hours).
Table 2: List of 24 BTA skills  that were mapped to 49
concentrator repairs, with frequency in parentheses.
Eighteen (37%) repairs were completely resolved using only
BTA skills, and 28 (57%) repairs were resolved with a
combination of BTA skills and basic non-BTA skills from
Table 3. The other three repairs (one of which was a
multicomponent failure) required the advanced PCB skill. No
repairs required an entirely different skill set.
Skills (number of occurrences)
Electrical Connections •!Building and using a continuity
•!Selecting wire (3)
Mechanical Attachment •!Tools for adjusting bolts & screws,
choosing different heads (8)
•!Super glue/glue (7)
•!Zip ties (17)
Cleaning •!Using a damp cloth (1)
•!Cleaning inside of things (1)
•!Mounting motors (3)
•!Vibration problems (3)
•!Set screws (3)
•!Bent shaft (vibration & wobbling)
•!Loosen, tighten, low power (3)
•!Squealing, grinding, overheating,
foreign objects (3)
Plumbing Blockage •!Cleaning valves and tubes (1)
Connections •!Clamps (21)
•!Hose barb with screw clamps (11)
•!Cleaning (and inspection) (10)
Leakage •!Cutting tubes (1)
•!Finding holes/leaks (20)
Seals •!O-rings (4)
Batteries •!Substituting primary batteries (5)
A mean of 4.0 ± 2.3 skills were needed per repair. Multi-
component failures required more skills (mean 6.7 ± 4.2).
Plumbing and mechanical skills were used the most, however
competency across all knowledge domains was needed.
Twenty-five (51%) repairs required skills from two or more
Table 3: List of skills not in BTA library that were mapped to
concentrator repairs, with frequency in parentheses.
Nine skills are needed to perform routine preventive
maintenance for concentrators (Table 4). All BTA skills for
preventive maintenance except for calibration and cleaning
using compressed air were also mapped to repairs (Table 2).
The calibration skill describes how to test oxygen
concentration in the absence of an oxygen analyser. We also
added the basic skill “using an oxygen analyser” as this test
equipment may be available in some settings.
Mechanical Attachment •!Tools for adjusting bolts &
screws, choosing different heads
Calibration •!Oxygen concentrator
Cleaning •!Compressed air
•!Using a damp cloth
•!Cleaning inside of things
Plumbing Blockage •!Cleaning valves and tubes
Filters •!Cleaning (and inspection)
Power Supply Batteries •!Substituting primary batteries
Additional basic skill not in
•!Testing O2 concentration using
an oxygen analyser
Table 4: BTA and non-BTA skills required for preventive
maintenance of oxygen concentrators.
We were unable to explicitly address the issue of diagnosis in
this analysis. All the failures analysed were diagnosed and
repaired by MRC biomedical engineering technologists
(BMETs) with college-level electronics backgrounds. We had
no record of the steps taken to troubleshoot issues and
recommend repair solutions. That being said, based on failure
descriptions and repair notes, we estimate that 63% (31) of
the failures were likely diagnosable using BTA skills only.
For example, of the 31 diagnosable failures, the following
BTA diagnosis skills were mapped in our analysis
(frequencies in parentheses): how to find holes and leaks (7),
checking if a battery is dead (4), checking if a filter is dirty
(8), and using a continuity tester (for testing circuits) (4).
Other physical issues (e.g. faulty flowmeter (3), outlet
requiring re-attachment (4), or a pinched tube (1)) were likely
diagnosable upon visual inspection. Recognizing that
diagnosing a cause of failure can be more challenging than
the repair itself, diagnosis is included as a topic in our
proposed training programme.
3.2 Proposed Training Curriculum
As a result of this analysis, we propose that an oxygen
concentrator-specific training curriculum should include the
following topic areas:
•!Overview of the functionality of concentrators, and
their use in clinical settings
•!Overview of the main components of a concentrator
•!Overview of common concentrator failures and
strategies for diagnosis (based on results from )
•!Concentrator Skills Training
!8 BTA skills 
!1 additional basic skill (if analyser available)
!24 BTA skills (6 already covered above) 
!4 additional basic skills
!1 additional advanced skill (optional)
We believe that this proposed curriculum, consisting of 31
basic BTA-level skills, would be sufficient for the repair of
94% of the failures analysed, the exception being three
complicated PCB repairs. The additional topics proposed
complement the DHT-EWH skills-based training approach
for a more comprehensive overview of oxygen concentrator
operation and repair.
The proposed training curriculum for oxygen concentrators
would be sufficient for both routine preventive maintenance
and the repair of over 90% of concentrator failures. A key
component of this curriculum is a set of 31 basic skills that
have been identified based on evidence of commonly
observed concentrator failures and preventive maintenance
needs. These skills could be taught to a secondary school
graduate in about 2 hours each . Twenty-six of these skills
are part of the evidence-based curriculum designed for BTAs
by the DHT Lab and EWH, which has demonstrated positive
results in Rwanda .
Repairs that do not fall under this training approach are
electrical failures related to PCBs that require more advanced
knowledge to diagnose and repair. In our sample of repairs
we only observed three such repairs over a 7-year period.
Since all MRC technicians have a college-level electronics
background, these repairs were manageable in our setting.
All of the BTA knowledge domains were relevant to oxygen
concentrators, although the context is slightly different for
some bodies of knowledge (e.g. plumbing skills would be
applied to pneumatics, and motor skills applied to
Skill (number of occurrences)
•!Testing and replacing alarms and
•!Advanced PCB trouble-shooting and
component selection (3)
•!Using special gripping tools (for
replacing sieve beds) (4)
•!Pressure testing using a pressure
•!Removing old glue (4)
compressors). There may be other BTA skills not listed in
Table 2 that are relevant to concentrators, however they were
not required for any of the repairs analysed.
We did not explicitly address the issue of diagnosis, which
can often be more challenging than the steps required for the
repair itself. However, we believe over half of the
concentrator failures would have been simple to diagnose,
and several BTA skills related to failure diagnostics were
included in the mapping exercise. Diagnosis does not appear
to be a major barrier to the maintenance of concentrators.
Our analysis indicates that some device-specific training is
necessary in order to cover repairs for all observed failure
modes; for example, the handling of sieve beds, and checking
the pressure and oxygen concentration during preventive
maintenance and after repairs. The BTA curriculum does not
assume any theoretical knowledge of the principles of
operation of a device, but we felt it important to add such
topics in our proposed training curriculum.
One might debate the validity of device-specific training
versus a more comprehensive approach to BMET training for
a wide range of devices and potential modes of failure.
However, global health interventions are often targeted at a
specific illness or treatment method, and along with this
comes the mass-installation of a specific medical device,
concentrators being a good example , . An evidence-
based, device-specific training program could serve to
supplement or refresh existing BTA or BMET skills when
such a program is introduced to ensure that already time- and
resource-constrained health technology management
programs can adequately support the new equipment.
There is a growing recognition in the global health
community that task shifting of healthcare professionals could
improve efficiency and relieve financial pressures on
resource-constrained health systems . We hope the
analysis presented herein may contribute to this dialogue for
the profession of biomedical engineers and technologists,
demonstrating that a substantial portion of maintenance needs
for simple, low-cost technologies like oxygen concentrators,
could be shifted to lower skilled BTAs so that BMETs are
freed up for more technically complex diagnosis and repairs,
and other tasks related to health technology management.
Other medical devices similar in complexity to concentrators
where this could apply include: scales, blood pressure devices
(sphygmomanometer or non-invasive electric), nebulisers, or
simple mechanical ventilators and CPAP machines.
We acknowledge that having highly-skilled BMETs is crucial
for the management and scheduling of repairs and
maintenance, and for ensuring that quality is maintained.
However, evidence shows that most oxygen concentrator
repairs require a low skill level, and that simple preventive
maintenance for concentrators can be delegated to assistant
BMETS – or BTAs – who have been taught the appropriate
skills. A skills-based approach to technician training, such as
that offered by the DHT and EWH, could significantly
contribute to the long-term maintenance and longevity of
oxygen concentrators in low-resource settings where some
level of BMET support is available.
A limitation of this analysis is the small sample size of repair
work orders mapped to skills, however, the time period over
which these repairs took place was longer than any previous
assessment of concentrator functionality. To our knowledge,
no assessment of the skills required for repairs and
maintenance based on real-world data has ever been
conducted for oxygen concentrators. This represents an
important step in understanding concentrator maintenance
needs and the experience and skill level required to maintain
this life-saving technology in the long-term.
A skills-based approach to technician training in a low-
resource setting, such as that proposed in this paper or more
broadly by DHT and EWH, would be highly effective for the
repair and maintenance of oxygen concentrators, which are
simple, low-cost medical devices. Concentrator failures are
not very complex, and the knowledge required for repairs can
easily be taught to qualified people within a reasonable about
of time. Our proposed evidence-based training curriculum
includes important device-specific topic areas in addition to
basic skills in order to provide a comprehensive overview of
concentrator operation, maintenance and repair.
Dane Emmerling, research associate and technical
coordinator at Duke University’s Developing World
Healthcare Technologies Lab, is gratefully acknowledged for
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