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Received August 6, 2020, accepted February 16, 2021, date of publication February 27, 2021

Quality Assessment of Emergency Corrective 
Maintenance of Critical Care Ventilators within the 
Context of COVID-19 in São Paulo, Brazil

By A. E. L. Alvarado1, D. A. O. Rosa1, S. G. Mello2, M. S. Dias2, M. F. Barbosa2, K. N. Barros2, B. A. Lemos2, R. L. Vitorasso1, V. 
P. Bartholomeu1, P. P. Americano1, E. S. Filho1, J. C. T. Barros Moraes1, A. F. G. Ferreira Junior2, H. T. Moriya1

1 Escola politécnica, University of São Paulo, Brazil
2 Institute for Technological Research, São Paulo, Brazil

ABSTRACT

This technical report presents the quality assessment process for the emergency corrective maintenance of critical care ventilators 
in a node, IPT-POLI, of a voluntary network that is part of the initiative +Maintenance of Ventilators, led by the National Service 
of Industrial Training (SENAI) and its Integrated Manufacturing and Technology Center (CIMATEC) to perform maintenance on 
unused mechanical ventilators in the context of the COVID-19 pandemic in Brazil. A procedure was established for the quality 
assessment of equipment subjected to corrective emergency maintenance, covering the essential aspects of the three primary 
standards (ABNT NBR IEC 60601-1: 2010+A1:2016, ABNT NBR ISO IEC 62353: 2019, and ABNT NBR ISO 80601-2-12:2014) for 
performance and safety assessment. A set of nine critical care ventilators was evaluated considering the following parameters: 
leakage current, protective ground resistance, control accuracy, delivered oxygen test, and alarms. The evaluated ventilators 
underwent corrective emergency maintenance before performance and safety assessments. In the electrical safety tests, all 
equipment presented values prescribed for the standard. However, the assessment of ventilator parameters revealed that their 
performance was below the standard. Finally, quality assessment reports were sent to the clinical engineering departments at 
hospitals. Thus, it can be concluded that criteria selection for the quality assessment in critical care ventilators is crucial and of 
great significance for future pandemic scenarios, such as the situation experienced during the COVID-19 pandemic.
Keywords – Quality assessment, critical care ventilators, standards, corrective maintenance, ventilation modes, COVID-19.

Copyright © 2021. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY): Creative Commons - Attribu-
tion 4.0 International - CC BY 4.0. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) 
are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is 
permitted which does not comply with these terms.

INTRODUCTION

Faced with the pandemic due to the novel coronavirus 
(SARS-CoV-2), the Brazilian health system experienced 
limitations in the number of critical care ventilators due 
to the increased demand. These ventilators were funda-
mental for the treatment of patients suffering from the 
most severe levels of the disease. The number of beds in 
intensive care units at hospitals was monitored as the 

disease progressed, and it was observed that certain 
regions had insufficient capacity.1

The Institute of Technological Research (IPT) and the 
Escola Politecnica (POLI) of the University of São Paulo 
set up a laboratory (IPT-POLI) to perform maintenance, 
inspection, electrical safety tests, and quality assessment 

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Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

J Global Clinical Engineering Vol.4 Issue 1: 2021  28

of mechanical ventilators to provide support to public 
hospitals in São Paulo, Brazil. Medical devices that were 
unusable due to technical failures were repaired and 
returned to hospitals. There was a voluntary network of 
39 maintenance points in all Brazilian states, that are part 
of the national initiative (+Maintenance of Ventilators) 
led by the National Service of Industrial Training and its 
Integrated Manufacturing and Technology Center.

The maintenance and quality assessment processes 
were based on ABNT NBR 77, ABNT NBR ISO IEC 62353: 
2019, and ABNT NBR ISO 80601-2-12:2014. This tech-
nical report addresses the quality assessment process 
conducted during the first months of activity and the set 
of critical tests selected as criteria for quality assessment 
after the maintenance process. 

Specific electrical safety tests were conducted per ABNT 
NBR IEC 60601-1: 2010+A1:2016 (general requirements 
for basic safety and essential performance). The selected 
tests were leakage current to earth, to the patient, and 
in the medical device enclosure, considering the manu-
facturer's classification in accompanying documents.2

Another essential standard used for evaluation was 
ABNT NBR ISO IEC 62353: 2019 (recurrent test and test 
after repair of medical electrical equipment) that presents 
the requirements to be analyzed before the medical device 
is put into service, during maintenance and inspection, 
and after repair.3

The ABNT NBR ISO 80601-2-12:2014 (particular re-
quirements for basic safety and essential performance of 
critical care ventilators) provides tests to evaluate ventila-
tion modes, analyzed according to the pressure, volume, 
breath rate, inspiratory time, and oxygen concentration 
measurements. Also, the standard prescribes testing to 
describe several failure conditions and alarm verification, 
emphasizing alarm priorities.4

Critical care ventilators are medical life support de-
vices, and the maintenance and calibration processes 
must be evaluated carefully to guarantee electrical safety 
and essential performance in ventilation. However, in the 
crisis scenario, it was not possible to thoroughly conduct 
all recommended tests; hence, there was a need for a 

study to select the points considered critical within a set 
of standards.

A procedure for quality assessment of equipment 
subjected to corrective emergency maintenance was de-
veloped, covering the main aspects of the three standards 
for performance and safety assessment. This procedure 
was applied to a small set of critical care ventilators, and 
the results are presented and discussed.

METHODS

The Electrical and Optical Equipment Laboratory of 
IPT and the Testing and Calibration Division of POLI 
were used to regularly conduct electrical safety tests on 
medical equipment before the COVID-19 pandemic and 
joined skilled labor metrology systems for this endeavor. 
IPT-POLI organized four areas inside the IPT campus 
(São Paulo, Brazil) to conduct maintenance and quality 
assessment procedures. A brief description of these areas 
is presented below. The medical devices were registered 
and disinfected in a reception area. After 12 h, critical care 
ventilators were transferred to the waiting area, which 
is also utilized to store devices that were not compliant 
with the requirements. Then, maintenance and quality 
assessment procedures were performed in the service 
area. This two-room area had four workbenches, two for 
electrical safety evaluation and two for ventilation as-
sessment. Two oxygen gas cylinders, medical oxygen (99 
%) and high-purity oxygen (99.995 %), of 10 m^3 with 
two-stage regulators (from 4–6 bar) (PRG-108, Prostar, 
Brazil) and an air compressor (1201BF, SCHULZ, Brazil) 
were connected to a delivery system in the service area to 
supply oxygen and air. Compressed air and oxygen lines 
were installed to supply an adjustable pressure between 
4.5–5.5 bar on each workbench to accommodate critical 
care ventilators. Finally, compliant medical devices are 
stored in the dispatch area.

Leakage current measurement

An electrical safety analyzer (601 Pro Series, Fluke, USA) 
was used to perform the tests. Briefly, the test consisted 
of supplying the medical device with 110 % of the rated 
electrical voltage, measuring the leakage current under 
normal conditions for all parts indicated by the ABNT 
NBR IEC 60601-1: 2010+A1:2016 (leakage current to 



29 J Global Clinical Engineering Vol.4 Issue 1: 2021

Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

earth, to the patient, and the enclosure). The test must 
be repeated by applying the electrical failures prescribed 
for the standard and measuring the corresponding leak-
age current. Critical care ventilators in this study, per the 
manufacturer, were classified as Class I. This classification 
refers to medical equipment that has basic insulation and 
grounding protection against electrical shock. The standard 
also provides the permitted limits for Class I equipment: 
leakage current (<5 mA), patient leakage current (<10μA), 
and enclosure leakage current (<100μA).

Resistance of protective ground

An electrical safety analyzer (19032, CHROMA, Ger-
many) was used to perform the tests. The test consisted 
of circulating an alternating current of 25 A through the 
medical device. The ABNT NBR IEC 62353: 2019 standard 
was used for this test. The resistance of the protective 
ground was measured with an electrical safety analyzer 
and must be less than or equal to 300mΩ for equipment 
with a detachable power-supply cord.

Accuracy of control: Volume control and Pressure 
control inflation type

The prescriptions related to volume control and pressure 
control inflation type correspond to items 201.12.1.101 
and 201.12.1.102 of ABNT NBR ISO IEC 80601-2-12: 2014. 
To test the volume control inflation type, it is necessary to 
measure the volume (mL), inspiratory time (s), positive 
end expiratory pressure (PEEP) (hPa), respiratory rate 
(breaths/min), and fraction of inspiratory oxygen (FiO2)
(%). For the pressure control inflation type, it is necessary 

to measure pressure (hPa), inspiratory time (s), PEEP 
(hPa), respiratory rate (breaths/min), and FiO2(%).

During the first month (April), to verify the accuracy 

of control, the setup was adopted as described in items 
201.12.1.101 and 201.12.1.102 with modifications in 
resistance and compliance values, as shown in Figure 1. 
A ventilator tester (AVM100, NÉOS, Brazil) was used for 
data acquisition. An adult test lung (SmartLung Adult 
2000, IMTMedical, Switzerland), an air compressor, and 
gas cylinders of medical oxygen (99 %), and high-purity 
oxygen (99.995 %) were applied to vary some parameters, 
such as compliance (mL/hPa), resistance (hPa/L/s), air-
flow (L/min), pressure (hPa), and FiO2 (%).

Tables 1 and 2 list the parameters set for the critical 
care ventilators and test lungs. Dark gray columns rep-
resent the parameters adjusted in the test lung, and light 
gray columns denote the parameters configured in the 
critical care ventilator.

FIGURE 1. Experimental setup with the adult test lung and 
the ventilator tester. The orange arrow indicates the direction 
of the ventilator. 

TABLE 1. Adaptation of volume control inflation-type testing from item 201.12.1.101 of the ABNT NBR ISO IEC 80601-2-12: 2014 

Test
Number

Test lung parameters Ventilator Parameters

Compliance*
(mL/bar)

Linear
Resistance*

(hPa/L/s)

Volume
(ml)

Inspiratory
Time (s)

Set rate
(breaths/min)

FiO2
(%)

PEEP
(hPa)

1 60 5 500 1 20 21 5
2 60 20 500 1 20 21 10
3 25 5 500 1 20 21 5
4 25 20 500 1 20 21 10
5 25 20 300 1 20 21 5
6 25 50 300 1 20 21 10

(*) Modified values of compliance and resistance.



Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

J Global Clinical Engineering Vol.4 Issue 1: 2021  30

In May, IPT-POLI acquired another test lung simulator 
(Dual Adult TTL, Michigan, USA). The instrument made it 
possible for the laboratory to verify the control's accuracy 
(items 201.12.1.101 and 201.12.1.102) of critical care 
ventilators without any modification of resistance and 
compliance (Tables 3 and 4). Also, the capability of the 
test lung simulator increased the number of tests from 
six to eight. Figure 2 illustrates the experimental setup 
with the test lung simulator and the ventilator tester for 
this case.

Based on the ABNT NBR ISO IEC 80601-2-12:2014, all 
critical care ventilators must declare in their instructions 
for use the maximum error to expiratory volume, airway 
pressure (Paw), PEEP, respiratory rate, inspiratory time, 
and oxygen concentration.

TABLE 2. Adaptation of pressure control inflation-type testing from item 201.12.1.102 of the ABNT NBR ISO IEC 80601-2-12: 2014 

Test
Number

Test lung parameters Ventilator Parameters

Compliance*
(mL/bar)

Linear
Resistance*

(hPa/L/s)

Pressure**
(hPa)

Inspiratory
Time (s)

Set rate
(breaths/min)

FiO2
(%)

PEEP
(hPa)

1 60 5 10 1 20 21 5
2 60 20 15 1 20 21 10
3 25 5 25 1 20 21 5
4 25 20 25 1 20 21 10
5 25 20 15 1 20 21 5
6 25 50 25 1 20 21 10

(*) Modified values of compliance and resistance.
(**) Set pressure above PEEP level.

FIGURE 2. Test setup using test lung simulator (Dual Adult 
TTL, Michigan, USA). The orange arrow indicates the direction 
of the ventilator. 

TABLE 3. Volume control inflation-type testing of item 201.12.1.101 of the ABNT NBR ISO IEC 80601-2-12: 2014 

Test
Number

Test lung parameters Ventilator Parameters
Compliance

(mL/bar)
Linear

Resistance*(hPa/L/s)
Volume

(ml)
Inspiratory

Time (s)
Set rate

(breaths/min)
FiO2
(%)

PEEP
(hPa)

1 50 5 500 1 20 21 5
2 50 20 500 1 20 21 10
3 20 5 500 1 20 21 5
4 20 20 500 1 20 21 10
5 20 20 300 1 20 21 5
6 20 50 300 1 20 21 10
7 10 50 300 1 20 21 10
8 10 20 200 1 20 21 5



31 J Global Clinical Engineering Vol.4 Issue 1: 2021

Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

Delivered oxygen test

A ventilator tester (AVM100, NÉOS, Brazil) and the lung 
test were used, as shown in Figures 1 and 2 to check the 
oxygen sensor on the critical care ventilator. The test lung 
(SmartLung Adult 2000, IMTMedical, Switzerland) was 
adjusted to a resistance of 5 hPA/L/s and compliance of 60 
mL/hPA; in the case of the test lung simulator (Dual Adult 
TTL, Michigan, USA), it was configured with a resistance 
of 5 hPA/L/s and compliance of 50 mL/hPA. The critical 
care ventilator was configured for control pressure mode, 
inspiratory time (1 s), pressure (10 hPA), frequency (20 
breaths/min), and PEEP (5 hPA). The inspiratory oxygen 
concentration (FiO2) was measured as 25 %, 50 %, 75 %, 
and 100 %.

Alarm verification

A set of alarms were analyzed based on item 201.4.3, 
which was prescribed for ABNT NBR ISO IEC 80601-2-
12:2014. Alarm conditions were generated according to 
the indications for each sub-item. The evaluated alarms 
are listed in Table 5. 

Calibration and verification

Calibrated instruments are mandatory to perform 
maintenance and quality assessment procedures. The 
ventilator tester parameters were calibrated according 

TABLE 4. Pressure control inflation-type testing of item 201.12.1.102 of the ABNT NBR ISO IEC 80601-2-12: 2014 

Test
Number

Test lung parameters Ventilator Parameters

Compliance*
(mL/bar)

Linear
Resistance*

(hPa/L/s)

Pressure*
(hPa)

Inspiratory
Time (s)

Set rate
(breaths/min)

FiO2
(%)

PEEP
(hPa)

1 50 5 10 1 20 21 5
2 50 20 15 1 20 21 10
3 20 5 25 1 20 21 5
4 20 20 25 1 20 21 10
5 20 20 15 1 20 21 5
6 20 50 25 1 20 21 10
7 10 50 30 1 20 21 5
8 10 20 25 1 20 21 10

(*) Set pressure above PEEP level.

to Table 6 with requirements based on the ABNT NBR 
IEC 60601-2-12:2014 and the International System of 
Units. The ventilator tester was calibrated following the 
available laboratory standard (LMR Metrologia, certificate 
number L613420, 2020-04-23). 

TABLE 5. List of alarms 

Test 
Number Item Test

1 201.11.8.101.1 Technical alarm condition for power-
supply failure

2 201.11.8.101.2 Internal power supply
3 201.12.4.101 Oxygen monitor

4 201.12.4.104 Maximum limited pressure 
protective device

5 201.12.4.103.1 Ventilators intended to provide a 
tidal volume > 50 mL

6 201.12.4.105 High airway pressure alarm 
condition and protective device

7 201.12.4.106 PEEP alarm conditions
8 201.12.4.107 Obstruction alarm condition
9 201.12.101 Disconnection alarm condition

10 201.13.102 Failure of one gas supply



Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

J Global Clinical Engineering Vol.4 Issue 1: 2021  32

The electrical safety analyzer was calibrated for cur-
rent, voltage, frequency, and resistance (IPT-Laboratorio 
de Metrologia Eletrica/CTMetro, certificate number 
173117-101, 2019-05-16).

The IPT-POLI acquired a certified oxygen cylinder with 
a purity of 99.995 % (Air Products Brazil Ltda, certificate 
number 256461, 2018-11-19) to verify the ventilator's 
galvanic cell tester that needs to be verified every day 
before the first use. A nitrogen gas sample was used to 
emulate the absence of oxygen for verification of the tester. 

Uncertainty of measurement (U)

For the ventilator parameters, pressure (hPa), vol-
ume (mL), FiO2 (%), PEEP (hPa), and respiratory rate 
(breaths/min), three measurements were carried out 
and, consequently, the conventional quantity value and 
the measurement uncertainties were calculated.

To calculate measurement uncertainties, type A 
evaluation of measurement uncertainty, derived from a 
statistical source, and type B evaluation of measurement 
uncertainty, which is the information from the accuracy 
of the verification certificate and information from the 
instrument's manual, were used.

Type A and B uncertainties were integrated to provide 
a combined standard measurement uncertainty.5

For each test, leakage current, and resistance of the 
protective ground, only one measurement was taken, and 
type B uncertainties were adopted.

The uncertainties were calculated using combined and 
expanded uncertainties with a coverage factor (k = 2 and 
95.45 %) as prescribed in the ISO GUM series - Guide to 
the expression of uncertainty in measurement.6

Assessed critical care ventilators

In total, nine critical care ventilators from two large 
public hospitals in São Paulo were assessed. Seven critical 
care ventilators (Vela, Carefusion, USA) were evaluated in 
April (Tables 1 and 2). In May, two critical care ventilators 
(Inter 5 Plus, Intermed, Brazil) were assessed, as shown 
in Tables 3 and 4. The medical devices were named A, B, 
C, D, E, F, G, H, and I in this study. 

The maximum errors for evaluating the first seven 
ventilators (A, B, C, D, E, F, and G) (Vela, Carefusion, USA) 
were obtained from its instruction for use and should 
be per the listed values: expiratory volume ±10 % of the 
monitored volume, respiratory rate ±2 bpm, airway pres-
sure ±5 hPa, PEEP ±2 hPa, inspiratory time ±0.05 s, and 
oxygen percentage ±2 %. 

For the last two ventilators (H and I) (Inter 5 Plus, 
Intermed, Brazil), the maximum errors were: expiratory 
volume ±10 % of the monitored volume, airway pressure 
±0.05 cmH2O, PEEP ±5 cmH2O, inspiratory time ±0.05 s, 
and oxygen percentage ±5 %. 

Volume control inflation type and pressure control 
inflation type were evaluated for the ventilators using 
preset modes: continuous mandatory ventilation pressure 
control (CMV-PC) and continuous mandatory ventilation 
volume control (CMV-VC).

RESULTS

All ventilators passed electrical safety tests for protec-
tive ground resistance, leakage current, patient leakage 
current, and enclosure leakage current.

Tables 7 and 8 summarize the measurement results for 
ventilators that did not comply with the stipulated limits. 

TABLE 6. Calibration points for the ventilator tester 

Parameters Calibration points

Flow (L/min) 0.05, 0.1, 0.25, 0.5, 1, 10, 25, 50, 100

Low pressure (mbar) 0, 5, 10, 15, 20, 30, 60, 120

High pressure (bar) 0, 2, 4, 5, 8, 9.5

Barometric pressure 
(mbar) 650, 700, 750, 800, 850, 900

Volume (mL) 0.005, 0.01, 0.02, 0.03, 0.05, 0.2, 0.3, 
0.5, 1, 1.5

Inspiratory time (s) 0.2, 0.4, 0.6, 1, 2

Respiratory rate (breaths/
min) 10, 15, 20, 25, 30, 60, 80

FiO2  (%) 21, 30, 60, 80, 90, 100



33 J Global Clinical Engineering Vol.4 Issue 1: 2021

Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

Because of the ventilators' problems, alarm verification 
was performed only on ventilators A, H, and I. All venti-
lators were not compliant with the oxygen level alarm.

DISCUSSION

The IPT-POLI adopted some of the essential performance 
requirements prescribed by item 201.4.3 ABNT NBR ISO 
IEC 80601-2-12:2014 to evaluate critical care ventilators. 
Tables 201.103 and 201.104 of items 201.12.1.101 and 
201.12.1.102 of ABNT NBR ISO IEC 80601-2-12: 2014 
were taken into consideration; however, within the first 
weeks, due to the limitations of the available test lung at 
IPT-POLI, the values of resistance and compliance were 
adapted according to the nearest values of resistance and 
compliance, as these configuration scenarios were shown 
in Tables 1 and 2. Another point was the time to carry out 
all 21 items in Tables 201.103 and 201.104. As hospitals 
urgently needed critical care ventilators due to COVID-19, 
only the first six test numbers were performed. All tests 
were performed with FiO2 adjusted to 21 % (atmospheric 
concentration) to evaluate the accuracy of the control and 
the oxygen concentrations were evaluated separately.

After the test lung simulator (Dual Adult TTL, Michigan, 
USA) was acquired, all tests to verify the control's accuracy 
were conducted using Tables 3 and 4. It was not possible 
to fully assess ventilators according to Tables 201.103 and 
201.104 because the test lung did not attend the prescribed 
compliance values (0.5, 1, and 3 hPa/L/s) for neonatal 
ventilators; nevertheless, the setup made it possible to 
assess critical care ventilators for adult configuration.

The purchased equipment (test lung and ventilator tester) 
to assess the volume and pressure control inflation-type 
modes were those with the shortest delivery time. The 
equipment was not the most capable; they lacked some 
features, such as external trigger input and well-sampled 
data; however, they met the quick application criteria.

Tables 7 and 8 indicate ventilators that did not com-
ply with the delivered oxygen, volume, and pressure 
control inflation-type tests. This was expected because 
ventilators were out of use for more than two years and 

received only emergency maintenance without replacing 
the maintenance kit.

The FiO2 The measurement test was essential to evalu-
ate the delivered oxygen; as shown in Tables 7 and 8, eight 
ventilators did not comply with the prescribed limits due 
to problems with internal leakages and control valves. 
External blenders controlled the percentage of oxygen in 
the ventilators (Inter 5 Plus, Intermed, Brazil); the blend-
ers presented leakages in all configurations (21–100%). 
Critical care ventilators commonly use galvanic cells to 
measure oxygen concentration, and those cells, depending 
on the manufacturer, have a life span of approximately 
1–2 years. Also, eight ventilators did not monitor oxygen 
concentration correctly because of problems related to 
the galvanic cell or its absence. 

Leakages in the ventilator breathing system (devices 
E and I) were observed during the tests. 

One significant issue was noticed during tests with high 
medical oxygen concentrations, and the two ventilators 
presented inconsistent results. The results were double-
checked with a high-purity oxygen delivery system, and 
there were improvements in the performance of both 
ventilators. Therefore, we noticed that the pressure loss 
in the delivery system of medical gas during high flow 
occurred due to particle debris in the pipes, which were 
removed.

Even though pressure setup in critical care ventila-
tors was performed extensively using pressure values 
in mbar or cmH2O by the clinicians, the ABNT NBR ISO 
80601-2-12:2014 indicated pressure values in hPa. Even 
these units of measurement present a slight difference 
between them.

At the end of each critical ventilator quality assess-
ment, all evaluated parameters were summarized in a 
quality assessment report and forwarded to the hospital's 
equipment control staff. Therefore, the quality assessment 
report could play an important role in hospital equipment 
usage decisions during the pandemic period. 



Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

J Global Clinical Engineering Vol.4 Issue 1: 2021  34

TABLE 7. Results of the critical care ventilators (Vela, Carefusion, USA) assessment 

Continuous mandatory ventilation volume control (CMV-VC)

Ventilator Test
number

Results (mL)

Tidal volume Uncertainty of measurement
(U)

C 1 570 13

E 1 96.4 7.2

Continuous mandatory ventilation pressure control (CMV-PC)

Ventilator Test
number

Results (mL)

Pressure Uncertainty of measurement
(U)

E 1 37.1 1.5

F 4 33.22 0.47

Oxygen concentration (%)

Ventilator Set value Measured Value* Uncertainty of 
measurement (U) Monitored value

A 50 52.20 0.68 52

B
75 71.07 0.86 133

100 82.97 0.90 155

D

25 29.27 0.41 24

50 46.47 0.59 30

75 68.57 0.84 38

100 94.8 1.3 48

E

25 25.57 0.34 **

50 47.40 0.56 **

75 68.40 0.80 **

100 87.6 1.2 **

F

25 27.00 0.33 **

50 62.03 0.76 **

75 89.8 1.1 **

100 99.9 1.2 **

G
50 54.50 0.81 63

75 82.83 0.97 100
(*) This refers to the monitored O2  % value displayed on the ventilator..
(**) The monitored O2  % value is not shown because the galvanic cell was not installed.



35 J Global Clinical Engineering Vol.4 Issue 1: 2021

Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

TABLE 8. Results of the critical care ventilators (Inter 5 Plus, Intermed, Brazil) assessment

Continuous mandatory ventilation volume control (CMV-VC)

Ventilator Test
number

Results (mL)

Tidal volume Uncertainty of measurement
(U)

H

2 392 10
3 407.1 9.8
4 447 11
6 261.8 6.7
7 265.6 8.0
8 170.5 4.3

I

2 395.3 12
3 421 10
6 262.4 6.1
8 168.1 4.0

Continuous mandatory ventilation pressure control (CMV-PC)

Ventilator Test
number

Results (mL)

Pressure Uncertainty of measurement
(U)

H
1 15.8 0.7
3 32.1 0.8
8 35.0 0.5

I
1 17.4 0.9
3 32.7 0.9
8 37.0 0.7

Oxygen concentration (%)

Ventilator Set value Measured Value* Uncertainty of 
measurement (U) Monitored value

H
25 22.6 0.3 **
50 44.4 0.6 **
75 69.7 1.7 **

I
25 28.9 3.7 **
75 69.2 0.5 **

100 93.9 1.1 **
(*) This refers to the monitored O2  % value displayed on the ventilator..
(**) The monitored O2  % value is not shown because the galvanic cell was not installed.



Alvarado, Rosa, Mello, Dias, Barbosa, Barros, Lemos, Vitorasso, Bartholomeu, Americano, Filho, Barros Moraes, Ferreira Junior, Moriya: 
Quality Assessment of Emergency Corrective Maintenance of Critical Care Ventilators within the Context of COVID-19 in São Paulo, Brazil

J Global Clinical Engineering Vol.4 Issue 1: 2021  36

CONCLUSION

Although all medical devices underwent corrective 
maintenance, eight out of nine failed the delivered oxygen 
test. Moreover, eight ventilators did not monitor oxygen, 
and four ventilators were not compliant with volume 
control and pressure inflation tests. The results are sum-
marized in Tables 7 and 8.

Notwithstanding the urgent requirement of critical care 
ventilators for COVID-19, the performed tests revealed 
the necessity of conducting quality assessment after the 
maintenance of critical care ventilators to avoid risk to 
patients. 

Justified by the fact that severe COVID-19 cases required 
safe delivery of ventilation oxygen support,7,8 the tests 
listed in this study aimed to cover the basis of ventilation 
assessment to guarantee the accuracy of the critical care 
ventilator's performance. 

The minimum infrastructure and instrument require-
ments to perform a quality assessment of emergency 
corrective maintenance of critical care ventilators during 
the beginning of COVID-19 in Brazil are presented herein.

CONFLICT OF INTEREST

The authors declare that they have no conflict of interest.

ACKNOWLEDGEMENTS

This study was financed in part by: the endowment fund 
of University of Sao Paulo Engineering School" Amigos da 
Poli" (+Ventiladores project) and Sao Paulo State Govern-
ment (42960P - Comitê de Crise do COVID-19).

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