Splitting Vents

Rightfully so the world is going crazy over the ventilator shortage. Social media is blowing up on the topic. The societies have published position statements against doing it which make some valid points but are overall complete nonsense. New York Presbyterian has published guidelines which are awesome. PulmCrit‘s Josh Farkas is also developing great content on it which can be seen here and here. Also see this article from Hannah Pinson below as well.

To solve the shortage, I’m seeing people work down two main pathways. The first is that industrial players, academics, and Makers alike are rapidly developing simple ventilators. Most are basically a mechanical hand which squeezes an ambu bag at a set rate. In my opinion they are cute but as of yet I don’t see them as providing good quality ARDSnet ventilation. I fear we’re investing in and consuming valuable resources with something that will kick the mortality can down the road in terms of Covid19. For trauma patients with fundamentally healthy lungs, I’m all for it but the jury is out in terms of Covid19 lungs. The second pathway, is to split ventilators. It’s been done before with real humans, and it’s being done now in NYC but we can and should improve how we’re doing it.

To help, I’m trying my best to coordinate a “Split Vent” team comprised of some some very dedicated and talented people including (Nate Surls, Joe Koberg, Paul Holland, Brian Overshiner, Dr. Paul Yearling, Timothy Nisi and more). Everything we do is open source, licensed under under Creative Commons 4.0. Download it, hack it, re-contribute it — please! Here’s what we’ve been up to:

1) Basically in line with the ventilation approach described in the outstanding article by Hannah Pinson we have developed 3d printable restrictor valves that connect directly in line with ventilator tubing right before the wye. We’ve tested them in the lab and we have fine control of ventilation to each individual patient. The design is changing by the hour as we test, and ultimately we’ll get them published on GitHub but in the interest of sharing the design now below are the STL files for what we have. We will get more printing and assembly instructions out as soon as we can. Also below is a 3d printable splitter. All connections are the iso standard 22mm.

2) Although you can monitor patients using end tidal CO2 and serial arterial blood gasses, this isn’t ideal. As such, we are working on a monitoring system which will essentially give each patient their own “vent screen” with pressure, flow, and volume waveforms on it. Something that looks like this:

The system will run on a Raspberry Pi Zero computer ($10 each, Adafruit is willing to source them in quantity for healthcare applications) and display the real time curves on any HDMI monitor. Future plans are to add alarming. Sensirion, an amazing sensor company in Switzerland is actively ramping up production on their SMF3300 mass flow sensor and although their out of stock from DigiKey, Mouser, etc (we bought them all) they are putting in 200% effort to get us (and other sites) more this week. More to come on this as we get our prototype functional. If anyone has programming / engineering resources especially with signal processing we’re happy to have help.

If anybody has thoughts on what we are doing, or wants to contribute please be in touch.