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Abstract and Figures

Coronavirus disease 2019 (COVID-19) has created an unprecedented need for breathing assistance devices. Since the demand for commercial, full-featured ventilators is far higher than the supply capacity, many rapid-response ventilators are being developed for invasive mechanical ventilation of patients. Most of these emergency ventilators utilize mechanical squeezing of bag-valve-masks or Ambu-bags. These "bag squeezer" designs are bulky and heavy, depends on many moving parts, and difficulty to assemble and use. Also, invasive ventilation requires intensive care unit support, which may be unavailable to a vast majority of patients, especially in developing countries. In this work, we present a low-cost ($<$\$200), portable (fits in an 8"x8"x4" box), non-invasive ventilator (NIV), designed to provide relief to early-stage COVID-19 patients in low-resource settings. We used a high-pressure blower fan for providing noninvasive positive-pressure ventilation. Our design supports continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BiPAP) modes. A common concern of using CPAP or BiPAP for treating COVID-19 patients is the aerosolization of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We used a helmet-based solution that contains the spread of the virus. Our end-to-end solution is compact, low-cost ($<$\$400 including the helmet, viral filters, and a valve), and easy-to-use. Our NIV provides 0-20 cmH$_{2}$O pressure with flow rates of 60-180 Lmin$^{-1}$. We hope that our report will encourage implementations and further studies on helmet-based NIV for treating COVID-19 patients in low-resource settings.
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A low-cost, helmet-based, non-invasive ventilator for COVID-19
Yasser Khan
Department of Chemical Engineering, Stanford University,
443 Via Ortega, Stanford, CA 943054125, USA.
Hossain Mohammad Fahad
Serinus Labs, Inc. 2150 Shattuck Ave, Berkeley, CA, 94704-1370, USA.
Sifat Muin
Department of Civil and Environmental Engineering,
University of California, Berkeley, CA 94720, USA
Karthik Gopalan
Department of Electrical Engineering and Computer Sciences,
University of California, Berkeley, California 94720, USA.
(Dated: May 25, 2020)
Coronavirus disease 2019 (COVID-19) has created an unprecedented need for breathing assistance
devices. Since the demand for commercial, full-featured ventilators is far higher than the supply
capacity, many rapid-response ventilators are being developed for invasive mechanical ventilation of
patients. Most of these emergency ventilators utilize mechanical squeezing of bag-valve-masks or
Ambu-bags. These “bag squeezer” designs are bulky and heavy, depends on many moving parts, and
difficulty to assemble and use. Also, invasive ventilation requires intensive care unit support, which
may be unavailable to a vast majority of patients, especially in developing countries. In this work,
we present a low-cost (<$200), portable (fits in an 8”x8”x4” box), non-invasive ventilator (NIV),
designed to provide relief to early-stage COVID-19 patients in low-resource settings. We used a
high-pressure blower fan for providing noninvasive positive-pressure ventilation. Our design supports
continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BiPAP) modes.
A common concern of using CPAP or BiPAP for treating COVID-19 patients is the aerosolization
of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We used a helmet-based
solution that contains the spread of the virus. Our end-to-end solution is compact, low-cost (<$400
including the helmet, viral filters, and a valve), and easy-to-use. Our NIV provides 0-20 cmH2O
pressure with flow rates of 60-180 Lmin-1. We hope that our report will encourage implementations
and further studies on helmet-based NIV for treating COVID-19 patients in low-resource settings.
The coronavirus disease 2019 (COVID-19) is a sys-
temic disease that primarily injures the respiratory sys-
tem and may cause severe alveolar damage and pro-
gressive respiratory failure [1, 2]. Initial reports from
China suggested approximately 15% of individuals with
COVID-19 develop moderate to severe disease and re-
quire hospitalization and oxygen support, with a further
5% who require admission to an intensive care unit (ICU)
and supportive therapies including intubation and me-
chanical ventilation [3]. But mortality rates were found
to be high among hospitalized COVID-19 patients requir-
ing intubation [4]. On the other hand, early interven-
tions with oxygen therapies and breathing supports have
shown to reduce the need for intubation and complica-
tions in respiratory failure patients while increasing sur-
vival rates [5]. In this scenario, non-invasive ventilation
becomes a viable measure for managing COVID-19 pa-
tients with acute respiratory distress syndrome (ARDS),
early in the disease.
Non-invasive ventilation refers to breathing support
yasser.khan@stanford.edu
delivered through a non-invasive method instead of in-
vasive approaches, such as intubation or tracheostomy.
It provides positive air pressure to the patient to recruit
collapsed alveoli, improving blood oxygen levels, as well
as reducing carbon dioxide levels. In developing coun-
tries such as Bangladesh, the use of full-featured me-
chanical ventilators (MVs) is hindered by their high cost
($15,000 per unit), limited availability, and requirement
of associated ICU beds and expert staffing for operation.
Currently, there are about 1267 MVs available for use in
Bangladesh [6]. But the demand for ventilators imposed
by COVID-19 at its peak is projected to be much greater.
To address the insurmountable need for ventilators,
many rapid-response ventilators are being developed for
invasive mechanical ventilation. Most of these emergency
ventilators use mechanical squeezing of bag-valve-masks
or Ambu-bags – originally developed at Massachusetts
Institute of Technology (MIT) in 2010 [7]. These “bag
squeezers” do not need compressed air or O2, however,
they are bulky and heavy, depends on many moving
parts, and difficulty to assemble and use. These prac-
tical challenges are huge impediments toward using bag-
squeezer-ventilators for supporting COVID-19 patients
over many days. An alternate approach is to use conven-
arXiv:2005.11008v1 [physics.med-ph] 22 May 2020
2
a
Oxygen
Room air
Non-invasive ventilator
Touch-screen
display
DC
blower
Motor
controller
Pressure
sensors
Air pressure (0-20 cmH2O)
Air flow (60-160 Lmin-1)
b
Viral
filter
PEEP
valve Inlet
Outlet
Air supply Patient
c
1 cm
Touch-screen
display
DC
blower
Motor
controller
Pressure
sensors
Viral
filter
PEEP
valve
NIV
helmet
Micro-
controller
Realtime
clock
Oximeter
connection
SD card
Oxygen
inlet
Inlet
Outlet
Figure 1. Overview of the helmet-based, non-invasive ventilator (NIV) for COVID-19. (a) Schematic showing the
helmet-based(NIV). Room air and 100% oxygen are mixed according to the fraction of inspired oxygen (FiO2) requirements.
The NIV is controlled using a touch-screen display, where the user chooses the driving conditions of the direct current (DC)
blower. A motor controller drives the DC blower. The whole system is operated using an Arduino Due microcontroller. Two
pressure sensors monitor the pressure and flow of the NIV. The output of the blower connects to the inlet of the helmet. Two
viral filters are used on the inlet and outlet sides to contain the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Besides, a positive end-expiratory pressure (PEEP) valve is used at the outlet. (b) Photograph of the NIV. The Arduino Due
microcontroller is mounted from the back. Different parts for the NIV are shown - realtime clock, secure digital (SD) card,
touch-screen display, pressure sensors, DC blower, motor controller, and a port for connecting an oximeter. (c) Photograph of
a person wearing the helmet with the essential components for helmet-based NIV. The air out from the NIV connects to the
inlet of the helmet through a viral filter. At the outlet side, a viral filter contains the spread of SARS-CoV-2, and a PEEP
valve determines the PEEP setting of the whole system.
3
tional NIVs, which are significantly less expensive with
no increased mortality associated with the usage [8, 9].
The availability of non-invasive respiratory support will
be valuable for many patients or as a temporary bridge.
One of the major concerns of using NIVs such as con-
tinuous positive airway pressure (CPAP) and bilevel pos-
itive airway pressure (BiPAP) for COVID-19 patients is
the risk of the aerosolization of the severe acute respira-
tory syndrome coronavirus 2 (SARS-CoV-2), and trans-
mission from the patients to the health care workers
(HCWs) [10]. The main reason for generating aerosols us-
ing CPAP and BiPAP is the high pressure (>10 cmH2O
) used in these devices. SARS-CoV-2 can travel fur-
ther and stay longer in the air when transmission occurs
through aerosols [11]. Therefore, in order to minimize
exposure to the virus, proper provisions are necessary.
It is recommended to operate CPAP and BiPAP NIVs
for treating COVID-19 patients in negative pressure
rooms, which ensures SARS-CoV-2 is contained within
the room, and the HCWs are advised to take adequate
protective measures. Hence, NIV usage faces further con-
straints. Merging helmet-based solution with noninvasive
positive-pressure ventilation (NIPPV) is an elegant solu-
tion that addresses the aerosolization of SARS-CoV-2 by
containing the virus inside the helmet.
In this work, we report a low-cost, portable, plug
and play, NIV which can provide breathing support to
COVID-19 patients in low resource settings. The device
is an end-to-end solution with a helmet interface. The
helmet, which is equipped with virus filters, minimizes
virus exposure to HCWs while providing support to pa-
tients in need of positive pressure ventilation. The NIV
is portable (fits in an 8”x8”x4” box) and has an easy-to-
use touch-screen interface. Using a high-pressure blower
fan, we can provide CPAP and BiPAP modes. Our NIV
provides 0-20 cmH2O pressure with flow rates of 60-160
Lmin-1. Furthermore, our whole system is <$400, which
includes the NIV, a helmet, viral filters, and a PEEP
valve, which is 40 times less expensive than an MV and
5 times less expensive than a conventional NIV making
it a fitting solution for low-to-medium income countries
like Bangladesh.
I. RESULTS
Helmet-based, non-invasive ventilator for COVID-19
Ventilators provide precisely measured mix of room
air and oxygen to the patients with pressure and flow
controls. Typically compressed air and oxygen sources
are connected to the ventilator unit. Depending on the
fraction of inspired oxygen (FiO2) requirements, room
air and oxygen are mixed in different ratios. The bag
squeezer ventilators provide air flow by the mechanical
squeezing of Ambu-bags. Our NIV uses a direct cur-
rent (DC) blower for providing adequate air pressure and
flow. Figure 1 provides an overview of the fully integrated
helmet-based NIV system used in this work. The setup is
shown schematically in Figure 1a. Room air and oxygen
are mixed in the NIV. A port is provided to the user to
connect to an oxygen source, while room air is automat-
ically used by the blower. Typically, an oxygen cylinder
with a flow upto 15 Lmin-1 is connected, while it is possi-
ble to connect two oxygen cylinders with a flow up to 30
Lmin-1 to increase FiO2. The air outlet of the NIV con-
nects to the inlet of the helmet. Two viral filters are used
at the inlet and outlet connections to contain the SARS-
CoV-2. Furthermore, a positive end-expiratory pressure
(PEEP) valve is used at the outlet.
The integrated control electronics module is shown in
Figure 1b. The control electronics for the NIV incor-
porate commercial off-the-shelf (COTS) components for
control, sensing, and actuation and can operate in ei-
ther CPAP or BiPAP mode. An Arduino Due micro-
controller is at the heart of the system which controls a 12
V DC air blower to deliver pressurized air to the patient
helmet. The blower used here is a 50W air pump that can
generate a maximum static pressure of 28 cmH2O and a
maximum flow rate of 240 Lmin-1 at a current draw of
4 A. The blower speed/pressure is controlled by Arduino
enabled pulse width modulation (PWM) at 1 kHz and a
high power motor driver capable of providing at least 4
A of DC. A 2.8” touch-screen provides a simple and intu-
itive user interface to the system, where clinically impor-
tant parameters such as pressure, inspiratory:expiratory
(I:E) ratio, breaths per minute (BPM) can be set and
monitored. This touch-screen also comes integrated with
a secure digital (SD) card reader, providing the option
for data collection during patient treatment. The blower
pressure is monitored using a board mount COTS sensor
with a -50 kPa to 50 kPa operating range and a sensitiv-
ity of 1 kPa·mV-1. Additionally, this pressure sensor is
also used to detect leaks and tubing disconnects. A board
mount differential pressure sensor with a operating range
of -6 kPa to 6 kPa is used to measure the compressed air
flow rate. An additional function of this differential pres-
sure sensor is in the automatic triggering of inspiration
and expiration to enable patient-system synchronization
in the BiPAP operating mode. To indicate potential sys-
tem or user faults such as pressure leaks or accidental
tubing disconnections, a magnetic DC buzzer is used to
generate an audible alarm. Figure 1c shows a person
hooked up to the helmet-based NIV. The filters and the
PEEP valve are also shown in the photograph.
The entire NIV system is integrated onto a cus-
tom printed circuit board (PCB) and housed inside an
8”x8”x4” polyvinyl chloride (PVC) enclosure, as de-
picted in Figure 2a-c. The touch-screen display and the
buzzer are placed on the top of the casing, while Air
outlet from the NIV, the oxygen inlet, and the oxime-
ter connection are located on the right-side of the casing.
One oxygen cylinder with a flow rate up to 15 Lmin-1 can
be connected to the oxygen inlet, while it is possible to
connect two oxygen cylinders with a flow rate up to 30
Lmin-1. A wired custom oximeter can be used with the
4
d
Top view Right-side view Left-side view
b ca
e
Touch-screen
display
Air outlet USB Power
12V DC
User interface
Increase Decrease Viral
filter
PEEP
valve
NIV
helmet
Inlet
Outlet
NIV system
Figure 2. Casing, user interface, and connection of the helmet-based NIV. (a) Top view of the NIV casing showing
the touch-screen display and the buzzer. (b) Right-side view of the NIV casing. Air outlet from the NIV, the oxygen inlet,
and the oximeter connection are shown. (c) The left-side view of the NIV casing. Universal serial bus (USB) connection, DC
power port, and the power switch are shown. (d) The user interface of the NIV. The user can set IPAP, EPAP, I:E ratio, and
BPM. (e) Photograph of the complete setup showing the NIV housed inside an 8”x8”x4” polyvinyl chloride (PVC) enclosure,
and the different components of air connections to the helmet.
NIV. On the left-side, universal serial bus (USB) port for
programming the Arduino, DC power jack (12 V), and
the power switch are located.
User inputs are taken with the 2.8” touch-screen as
shown in Figure 2d. The user can set inspiratory posi-
tive airway pressure (IPAP), expiratory positive airway
pressure (EPAP), I:E ratio, and BPM. IPAP and EPAP
pressures can be set from 5-20 cmH2O, I:E ratio of 1:1,
1:2, and 1:3 are supported. BPM can be adjusted from
10 to 30. Finally, the complete system setup with the
NIV and the helmet is displayed in Figure 2e.
Pressure and flow characterization
Pressure is the most important parameter in CPAP /
BiPAP-based NIVs. Also, helmet-based ventilation re-
quire high-flow, to reduce CO2rebreathing. A minimum
flow of 60 Lmin-1 is required for helmet-based NIVs. We
control the pressure setting of our NIV using PWM con-
trol signal, which is generated by the micro-controller
and sent to the motor driver. Figure 3a shows the pres-
sure vs. blower control PWM plot. While the blower
reaches up to 24 cmH2O at PWM settings of 255, the
pressure values are non-linear beyond PWM settings of
180. Therefore, we fixed the maximum pressure at 20
cmH2O for our NIV. The open-ended flow and pressure
plot is provided in Figure 3b. It is possible to reach up
to 160 Lmin-1 flow with the control settings, while the
absolute maximum of the blower is 240 Lmin-1 . The flow
depends on the set pressure, PEEP settings of the hel-
met, and the respiration of the patient. Since the flow of
60 Lmin-1 occurs at a pressure of 7 cmH2O, we recom-
mend a pressure difference of 7 cmH2O for operating the
5
a
d
f
c
e
Pressure reproducibility
Flow reproducibility
y = 7.3852x + 19.254
b
Continuous operation
Figure 3. Pressure, flow, and continuous operation characterization. (a) Pressure vs. blower control PWM plot.
The desired pressure from the blower is obtained by selecting the corresponding control PWM signal. (b) Flow vs. pressure
plot in an open-ended setting. The flow changes based on the set pressure, PEEP settings of the helmet, and the respiration
of the patient. (c) Pressure reproducibility of 5 different NIVs. 5, 10, and 15 cmH2O pressure were set and measured for each
NIV. We observed 1 cmH2O variation without feedback control. (d) Flow reproducibility of 5 different NIVs. 60, 100, and 140
Lmin-1 flow rate were set and measured for each NIV. We observed 10 Lmin-1 variation without feedback control. (e) To test
the continuous operation of the NIVs, we continuously operated one NIV at IPAP 15 cmH2O and EPAP 8 cmH2O for over 4
hours. (f) Zoomed-in in data for 25 s do not show any visible fluctuation from the set pressure values.
6
a
c
b
I:E = 1:2, BPM = 16
IPAP 16, EPAP 8 cmH2O, I:E = 1:2
IPAP 16, EPAP 8 cmH2O, BPM = 16
d
Leak started
Leak sealed
Reconnected
Disconnected
Figure 4. Pressure profile characterization. (a) Different pressure profiles of (i) IPAP 10 and EPAP 5 cmH2O, (ii)
IPAP 12 and EPAP 8 cmH2O, and (iii) IPAP 16 and EPAP 10 cmH2O were tested. All profiles were within 0.5 cmH2O error
margin. (b) BPM of 10, 20, and 30 were simulated to test different respiration rates of patients. (c) I:E ratios of 1:1 to 1:3 were
simulated. (d) Leak and disconnection tests preformed using the helmet setup, a CPAP pressure of 12 cmH2O was set, keeping
PEEP valve at 5 cmH2O. A leak was gradually generated which resulted in a pressure drop from 5 to 3 cmH2O. Similarly,
disconnection was simulated at the inlet hose, which resulted in a pressure drop to 0 cmH2O is a matter of a second.
7
helmet-based NIV.
The pressure and flow reproducibility testing were
done with 5 different NIVs (Figure 3c and d). Pressures
of 5, 10, and 15 cmH2O, and flows of 60, 100, and 140
Lmin-1 were set for the 5 NIVs. In the case of pressure
testing, we observed 1 cmH2O variation without feedback
control. As for the flow testing, we observed 10 Lmin-1
variation without feedback control. These measurements
were done using a one-time calibration shown in Figure
3a and b. All the NIVs were operated using the same
calibration curve. Using individual calibration for each
NIV will further improve the variability from device to
device.
Ventilators are operated for many hours to many days
without interruption. Therefore, it is essential to perform
continuous operation testing of the NIVs. We continu-
ously operated one NIV at IPAP 15 cmH2O and EPAP 8
cmH2O for over 4 hours (Figure 3e), we did not observe
any visible fluctuations from the set pressure values (Fig-
ure 3f). We are currently doing lifetime testing of the
device, which we will report in the next version of the
preprint.
CPAP and BiPAP modes for NIV
Both CPAP and BiPAP modes can be used for non-
invasive ventilation [12]. In the CPAP mode, only one
pressure is used. While BiPAP switches between two dif-
ferent pressure settings. During the inspiratory phase,
higher pressure is used, and during the expiratory phase,
lower pressure is used. To characterize the performance
of the NIV, we operated the device in different IPAP,
EPAP, I:E ratio, and BPM settings as shown in Figure
4a-c. Different pressure profiles of (i) IPAP 10 and EPAP
5 cmH2O, (ii) IPAP 12 and EPAP 8 cmH2O, and (iii)
IPAP 16 and EPAP 10 cmH2O were tested with the de-
vice to simulate patients with varying levels of pressure
needs. All the measurement were within 0.5 cmH2O er-
ror margin (Figure 4a). The respiration rate of patients
can vary from 10 to 30 BPM, we simulated BPM of 10,
20, and 30, as shown in Figure 4b. We also tested vary-
ing I:E rations - 1:1 to 1:3, as shown in Figure 4c. These
characterization shows that our device can be operated
in BiPAP mode if the need arises.
One of the biggest safety features of NIVs is leak and
disconnection detection. To detect leaks, we used the on-
board pressure sensor. Using the helmet setup, a CPAP
pressure of 12 cmH2O was set, keeping PEEP valve at
5 cmH2O. We then gradually created a leak as shown in
Figure 4d, top panel. The pressure dropped from 5 to
3 cmH2O, which was detectable by the pressure sensor.
This drop in pressure is used to trigger the leak alarm.
Using the same setup we simulated disconnection of the
inlet hose, the pressure goes to 0 cmH2O in a matter of
a second (Figure 4d, bottom panel), this pressure signal
is also used to trigger the alarm.
Initial human testing results
The efficacy of the NIV was tested by a human vol-
unteer testing using the complete setup – NIV with a
helmet, viral filters, and a PEEP valve. These sets of
experiments provided insight into the pressure and flow
settings required for helmet-based NIV. We used CPAP
pressure of 5, 7, and 9 cmH2O to test the low and medium
flow regimes of the NIV (Figure 5). The volunteer wore
a pulse oximeter for continuous monitoring of pulse oxy-
genation (SpO2) and heart rate (HR). The PEEP valve
was set to 5 cmH2O. In the low flow regime, <30 Lmin-1,
helmet-based ventilation is uncomfortable as indicated
by the volunteer – rated 5 on a 0-10 comfort scale (Fig-
ure 5b). We also observed fogging of the helmet, which
indicated inadequate flow. The pulse oximeter was used
to monitor the SpO2level of the volunteer. SpO2went
down slightly from 99% to 97% during the 7 min of test-
ing. Then, low to moderate pressure settings of 7 and 9
cmH2O were used. The volunteer reported much higher
comfort levels (Figure 5c-e). Also, we did not observe
fogging of the helmet during the tests, which is a poten-
tial indicator for CO2re-breathing and insufficient flow.
SpO2levels fluctuated between 99% and 97%, without
any evident trend. These experiments verify that a min-
imum flow of 60Lmin-1 is required for helmet-based ven-
tilation.
Proposed helmet-based non-invasive ventilation
administration protocol
In this section, we provide guidance for administering
the developed helmet-based NIV. This guidance is de-
signed as a tool to aid the use of the device alongside
clinical judgment. It should not be treated as a pre-
scriptive measure. Decisions relating to the escalation of
ventilatory support need to be made by experienced clin-
ical decision-makers. United Kingdom National Health
Service (NHS) guidelines have been used to outline the
protocol [13].
Among different breathing support CPAP is the pre-
ferred form of NIV support in the management of the
hypoxaemic COVID-19 patient. Its use does not re-
place invasive mechanical ventilation, but early applica-
tion may provide a bridge to it. Following are the sug-
gested use, device settings and monitoring guidelines for
helmet-based CPAP:
1. Suggested initial settings are 12 cmH2O + 15
Lmin-1 oxygen with a PEEP valve set at 5 cmH2O.
2. Aimed SpO2is 94% to 96% for patients with acute
respiratory failure.
3. Once CPAP/NIV has begun, the patient should
be reviewed over 30 min to detect failed response
or further decline. If the patient responds, hourly
monitoring must continue for a further six hours.
8
aPatient comfort
b
c d
e f
Comfortable
Uncomfortable
0
10
5
Patient comfort
Uncomfortable
Patient comfort
Uncomfortable
0
8
0
9
Comfortable
Comfortable
Figure 5. Human volunteer test results. (a) Pulse oxygenation (SpO2) and heart rate (HR) of the volunteer during the
helmet-based NIV tests. CPAP pressure of 5 cmH2O was used in this experiment. (b) Comfort during the experiment reported
on a 0-10 comfort scale. The volunteer reported comfort level of 5. (c) CPAP pressure of 7 cmH2O was used in this experiment.
(d) The volunteer reported comfort level of 8. (e) CPAP pressure of 9 cmH2O was used in this experiment. (f) The volunteer
reported comfort level of 9.
The frequency of assessment can be reduced if the
patient is stable.
4. Monitoring should focus on the regular measure-
ment of respiratory rate, work of breathing, oxygen
saturation, and heart rate.
5. Consider increasing CPAP support to 15 cmH2O
+ 30 Lmin-1 100% oxygen (2 cylinders) if needed.
PEEP valve can be adjust to 8 cmH2O.
6. If the condition remains stable or is improving, con-
tinue CPAP/NIV with a regular assessment.
7. A low threshold for intubation should be estab-
lished by the clinicians which may include a ris-
ing oxygen requirement, consistently rapid declin-
ing SpO2, consistently or rapidly increasing respi-
ratory rate, and increased work of breathing. This
should trigger immediate assessment for intubation
and mechanical ventilation if deemed appropriate.
This guidance is summarized in Figure 6.
Discussion
The available resources to address ventilation needs
are drastically different in developing countries. With
growing evidence that noninvasive positive pressure ven-
tilation results in a significant reduction in endotracheal
intubation [14], it is a promising low-resource treatment
plan for treating COVID-19 patients in developing coun-
tries. To facilitate this treatment approach, we pre-
sented an end-to-end, low-cost, helmet-based ventilator.
9
Category Clinical Status Suggested Action
Green RR ≥ 20 bmp with SpO2≤ 94%
Administer O2≤ 40% with conventional face
mask. If
SpO2
rises more than 94% observe and
monitor. No need for helmet NIV.
Yellow RR ≥ 20 bmp with SpO2≤ 94% with O2 40%
Start 15 Lmin-1 O2. If oriented and able to
tolerate the helmet NIV trial, CPAP with 12
cmH2O settings and PEEP at 5 cmH2O.
Orange
RR ≥ 20 bmp
with SpO2≤ 94% with 15Lmin-1 O2
and CPAP at 12 cmH2O
Start additional 15 Lmin-1 O2(2 cylinders).
Consider increasing CPAP settings to 15
cmH2
O.
PEEP may also be adjusted upto 8 cmH2O.
Red
RR ≥ 20 bpm with SpO2 ≤ 94% on 30 Lmin-1 O2
and CPAP at 15
cmH2O
and/or patient unable to
tolerate CPAP, obtunded/ disorientated, rising
FiO2needs, significant clinical decline
Urgent critical care review and prepare for
intubation.
Figure 6. Adult escalation plan following initial assessment and treatment for COVID-19 patients in hospital. These are
recommend based on the United Kingdom National Health Service (NHS) guidelines. We are actively working with doctors
to update the protocol for Bangladesh considering the limited supply of oxygen cylinders with the maximum flow rate of 15
Lmin-1.
Our device moves away from the bulky, heavy, difficulty
to assemble and use bag-squeezer-ventilators by using a
compact design that is portable and easy-to-use. Also,
we mitigate the aerosolization of SARS-CoV-2 with a
helmet-based approach. We hope we presented a com-
pelling case for our NIV for use in medium to low-to-
medium income countries. Nonetheless, further studies
and randomized clinical trials are required to evaluate the
efficacy and the benefits of helmet-based NIV in treating
COVID-19.
Disclaimer
We released this version of the preprint due to the ex-
traordinary circumstances of COVID-19. The developed
hardware and the results of this study have not been
medically approved. However, the system engineering ef-
forts and validation results indicate the potential for relief
to early-stage COVID-19 patients. We intend to intro-
duce helmet-based, low-cost, non-invasive ventilation to
healthcare professionals working under low-resource set-
tings. Our hardware should NOT be used for invasive
mechanical ventilation. Furthermore, we are improving
the software to enhance the hardware usage of the current
platform. The next version of the preprint will report the
on-going enhancements.
A provisional patent application has been filed based on
the technology described in this work.
Acknowledgements
This project was made possible by the generous sup-
port of the Bangladeshi students and alumni of UC
Berkeley and Stanford University. We would like to
thank Aurika Savickaite for providing us a helmet for
testing, Dr. Maurizio Cereda, Prof. Md Robed Amin,
Dr. Tarik Reza, Dr. Tanveer Ahmad, and Dr. Nakib
Shah Alam for helpful technical discussion, Prof. Taufiq
Hasan, Faisal Huda, Sheikh Waheed Baksh, Dr. Raisul
Islam, Dr. Shegufta Mishket, Yasser M. Tahid Khan, Dr.
Yaseer M Tareq Khan, Eusha Abdullah Mashfi, Minhaz
Khan, and Nicholas Vitale for helping us throughout the
10
project. We would also like to thank Prof. Ana Claudia
Arias and Prof. Miki Lustig for allowing us lab-access for
the fabrication of the casing. We also thank Bay Area
Circuits for providing us PCBs in an expedited manner.
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Chapter
The coexistence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), called the “overlap syndrome” (OS), is associated with an increased morbidity and mortality burden. Although the management of the OSA component is based on positive airway pressure (PAP) therapy, the treatment benefit seems to extend to the COPD part of the syndrome. PAP therapy in overlap syndrome is associated with an improvement in lung function, arterial blood gases, vascular function, COPD exacerbations, mortality, and quality of life.