2020 Barsan Emergency Medicine Research Day

1. Rapid development of a novel portable
negative pressure environment
Nate Haas, MD
Ben Bassin, MD; Sridhar Kota, PhD; Henrique A Puls, MD; Kevin R Ward, MD

2. Disclosures
▸ Sridhar Kota and Kevin Ward have submitted intellectual
property on the device through the University of Michigan.

3. Background
▸ The COVID-19 pandemic is rapidly straining hospital and
intensive care resources
▸ PPE and negative pressure room shortages face many
institutions
▸ Heated High Flow Nasal Cannula (HHFNC) may benefit
select patients with COVID-19

4. Background
▸ Aerosol generating procedures may place healthcare
workers and other patients at increased risk
– HHFNC, NIV, nebulized treatments
▸ COVID-19 transmitted via respiratory droplets, with limited
data suggesting possibility of airborne transmission
▸ Substantial need for innovative PPE and additional
negative pressure environments

5. Hypothesis
▸ A portable negative pressure environment could
confront these challenges with benefits for:
– Patients: increased use of aerosolizing therapies
• Increased HHFNC, NIV, nebulized treatments
• Avoidance of mechanical ventilation
• Earlier liberation from mechanical ventilation to HHFNC
– Healthcare workers: decreased exposure to respiratory droplets, including
pre-hospital setting
– Healthcare systems: decreased need for additional negative pressure rooms

6. Proposed solution
▸ Portable negative pressure
environment helmet
– PAPR with reversed directionality of
air flow
– Draws air up through loosely fitted
neck seal into helmet
– Air (+exhaled air/droplets) pass
through HEPA filter, out exhaust port

7. Air changes per hour
▸ >12 air changes per hour recommended by CDC
for negative pressure rooms
▸ Device has three fan settings –130, 210, and
320 L/min
▸ 274 air changes per hour can be achieved with
device for a patient on HHFNC

8. Multiple Provider Trial
Kyle Gunnerson, MD Cindy Hsu, MD Michael Tallman RRT
Emerg. Med/Critical Care Emerg. Med/Critical Care Respiratory Therapy

9. Air particle testing
▸ TSI Condensation Particle Counter
▸ Detects particles with size range 0.01 to
>1 micrometer
▸ COVID-19: 0.06-0.14 micrometers
▸ TSI Particle Generator
▸ Simulate additional droplet generation,
aerosolization, and viral shedding
▸ Simulated scenarios linked with
aerosolization including HHFNC and
nebulized treatments

10. Units: particles / cm3 air
Without device With device
Ambient room air 400-1000 N/a
HHFNC +
Nebulizer
46,000 518
HHFNC + Particle
Generator
27,351 804
Exhaust port N/a 43
Air particle testing

11. Interpretation
▸ Use of HHFNC with the device was associated
with no detectable increase in air particle counts
from background ambient air
▸ Device may mitigate aerosolization of respiratory
droplets while filtering particles from exhaled air
of the wearer

12. Limitations
▸ Single healthy volunteer
▸ Simulated model of aerosolization
▸ Limited generalizability to patients with COVID-
19

14. Retractable face shield Access to IJ CVC

15. Current Status
▸ Working with manufacturer to scale
▸ Scaling Production and Price
▸ Tweaks for disposable parts (majority of apparatus to be
disposable)
▸ SOP for cleaning: Certain parts can be sterilized (UV
and others)
▸ Successful reengineering of PAPR motors/filters to
reverse flow

16. Future direction
▸ Additional use in COVID-19 patients, particularly
those on HHFNC
▸If caring for a patient on HHFNC that may benefit,
please notify Ben Bassin or Nate Haas
▸ Future research
▸ Additional isolation strategies

17. System pulls air out
through the frame to
create high flow
negative pressure in
the tent
Negative pressure
source (high flow
suction) connects here
Virus Isolation Tent High flow air is
pulled from the tent
through these holes

18. Conclusions
▸ Rapid development and further study of a
portable negative pressure device may allow for
a novel innovation to benefit patients, healthcare
workers, and institutions alike.
▸ Future innovation and rapid assessment of
innovations are needed during the COVID-19
pandemic now more than ever.

19. Questions?
Nate Haas
haasn@med.umich.edu

22. CONFIDENTIAL
COVID-19 Pandemic
▸ Pandemic
▸ Approaching steep part of
the curve
▸ Potential to overwhelm
current hospital capacity
and resources

23. COVID-19 Highly Transmissible:
Severe Need for Negative Pressure Rooms
▸ Limited hospital supply
▸ Need to isolate patients with
symptoms in ER’s prior to and
during testing
▸ Need to hold patients who test
positive in ER
▸ Need to isolate patients who test
positive, need treatment but no
ICU treatment

24. Tested with Heated HFNC
▸ Rapid set up
– HFNC applied
– Helmet and neck cape placed over subject:
– Hand-held shop vacuum activated
– HFNC activated
▸ Inner head space cooled with air
pulled us through neck cape via
vacuum
▸ Comfortable and able to recline
without issue with pillow support
▸ Hearing slightly reduced due to HFNC
noise in helmet

25. Personal Protective Equipment (PPE)
Challenges
▸ Precious resource
▸ Protects health care
providers and patients
▸ Critical for both patients and
health care workers during
treatment with various
respiratory therapies

26. Heated High Flow Nasal Cannula (HFNC)
▸ Innovation in treatment of hypoxic
respiratory failure from many
causes
▸ Flows of 60 liters per minute
▸ Can be mechanical ventilator
sparing
▸ Can be helpful for early liberation
from mechanical ventilation
https://www.youtube.com/watch?v=cePJEx6qTvk

27. Heated High Flow Nasal Cannula (HFNC)
▸ Presents risk for use in COVID
patients
– High flow may cause aerosolization
especially in coughing patients
– Complicated by lack of negative pressure
rooms
– Covering with a mask is not well tolerated
– Many systems have prohibited use of
nasal cannula flows above 6 liters/min
– Many patients being intubated early and
potentially needlessly
– Similar challenges in using bronchodilator
aerosols

28. Novel portable negative pressure
environment
▸ Industrial Respirator with
Reverse Flow
▸ Potential Dual Solution
– Enable Use of HFNC
– Alleviate Shortage of
Negative Pressure Rooms

29. Fundamental Design
▸ Used in painting, chemical industry,
etc.
▸ Similar to Powered Air Purifier
Respirator (PAPR)
▸ Supplies clean air to inside of helmet
via fan unit and HEPA filter
▸ Hard and soft shell with some reusable
and sterilizable parts
▸ Models with liftable anti-fog face shield

30. Reengineering for COVID-19 and like Pandemics
▸ Reverse flow using small
vacuums
▸ Pulls room air up through neck
seal area
▸ Helmet air leaves and passes
through HEPA Filter
▸ Video demonstrates fog testing
– Fog introduced at flows greater than
HFNC: See videos to right
– Applied vacuums demonstrate no fog
leakage, even with open face shield

31. Helps to Enable Use of HFNC
▸ Use of HFNC without fear of aerosolization
– Particularly useful in coughing patients
– Environment within helmet is comfortable
• HFNC may be more comfortable with MiCRIS
• See video to right
▸ Early use in treatment of hypoxic respiratory failure
in persons of unknown COVID status
▸ Continued use possible if COVID positive
▸ Allow HFNC for earlier transition from those requiring
Mechanical Ventilation
▸ Liftable face shield allows for breaks to eat and drink
and for suction with reduce risk of contamination
▸ Mobile with patient to allow travel to procedures or
advanced imaging
▸ Hearing can be augmented with blue tooth enabled
phone, etc.

32. Enables Creation of Immediate Personal Negative
Pressure Environment
▸ Placement on suspected COVID
patients in ER creates de-factor
negative pressure room, even in
waiting room. Air exchanges much
greater than neg pressure room
▸ Creates de-facto negative
pressure room for admitted
patients not requiring an ICU
▸ Negative pressure environment
maintained if patient requires
movement (testing, bathroom, etc.)