Open Source Ventilator Project

[David Hempy]

As long as we're jiggling the Collexion handle, I'd like to share a project I've been working on over the past month -- and open source ventilator called Air Assist.

It's a ventilator designed for emergency use in the COVID-19 crisis. The fundamental design goal is to use readily-available materials to build a safe, functional ventilator. The design has no custom parts -- It does not require any tools beyond a screwdriver and an Amazon account. The entire BOM is under $300, and can be assembled in a day. 

The design centers around a Ball Valve Mask (BVM) or Ambu-bag, which are available in ample quantities in every hospital. It uses compressed air in a blood pressure cuff to actuate the BVM, controlled by an Arduino. Pressure sensors monitor in the airway, and the operator controls cycle time and the inspiration:expiration ratio. The unit can run in fully automated mode for an unresponsive patient, instantly switching to patient-triggered breath support if the patient is able to inhale. 

The volume air in each breath (tidal volume) is controlled via a double-action pneumatic cylinder, adjustable by the respiratory therapist in volume and speed. The fixed cylinder capacity is one of several fail-safes to ensure that we never blow up a patient in the event of a component failure.

Air expelled from the patient is also regulated in back pressure (called PEEP), to ensure the tiny air sacs in the lungs don't collapse completely. The contaminated air expelled by the patient is captured in a closed system and collected in the hospital vacuum circuits. 

I came into the project late in the the game, and have learned SO MUCH about things I thought I knew, and things I didn't even know existed. 

I've played with Arduinos before, but never very deeply. This project might sound like brain surgery, but at its core, this really is just a fancy version of Blink ... with brain surgery!

Things I knew *nothing* about coming into it include: pulmonary theory; pneumatics; FDA approval; barotrauma; medical device UI; liability, and more. Working with a team of doctors, nurses, designers, programmers, testers and illustrators, and not nearly enough sleep, we created our first breathing prototype in a few days, and had a demonstratable prototype in just over a week. We've demoed the unit to several doctors and nurses, with *enthusiastic* support. 

While Kentucky is not projected to be short of ventilators in hospitals, other areas are in greater need. Our project may be of the greatest value in third-world countries, epicenters like Itally and New York, as well as non-hospital environments like nursing home and prisons. 

I think we're on our fifth or sixth prototype iteration by now, and are currently pursuing FDA emergency approval.

Oh, what a wild ride it's been! 

If anyone wants to get involved, there is still work to be done. Of particular need is navigating the bureaucracy of FDA approval and developing a graphical UI separate from the controller. (maybe RasPi or Android-based)  Reach out to me if you'd like to join the team.

You can learn more about it at https://www.vent.guide/ , or watch some of my daily video journals at  https://www.youtube.com/playlist?list=PLKBDMJrxA9sdEUPxaVVC_-4Zkz2tbCIc1