SplitVent Update – March 29

As COVID19 cases pile up, including at the Indiana University hospitals, our team has been working incredibly hard to get a safe and effective split vent system ready for what seems like an inevitable need to ventilate multiple patients with a single ventilator. I’ll keep this as brief as I can.

The major updates from today:

  1. We’re one step closer to a final valve design. Nate Surls, Paul Holland, and Dr. Paul Yearling did an outstanding job designing and prototype printing it.
  2. We’re one step closer to a usable monitoring software. Joe Koberg in Atlanta has done an incredible job hacking a python-based system together heavily leveraging some phenominal open source biosignal processing code from BioPeaks.
  3. We did more lab testing today with only positive outcomes. I created an 8 minute video overview of the system and have posted it to YouTube (or see below).
  4. We reviewed everything with some of the ICU medical leadership at our hospitals as well as respiratory therapy and it sounds like they have the intention to scale up with implementation (still hoping we won’t ever need it). That means we’re going to be placing big orders for sensors and Raspberry Pis. We’re warming up the 3D printing lab and recruiting nible-fingered egineering students to start soldering!
  5. The SplitVent GitHub is now live and is being updated in real-time. This is where you can download the necessary 3D files as well as the source code for the monitoring system.

Things we are working on:

  1. Updates to the monitoring software to bring it out of the pacman era and into the 21st century. We will soon have a full featured graphical display with graphs and nicer display of the relevant information (tidal volume, flows, minute ventilation, etc).
  2. We continue to refine valve and other 3D printed part designs including connectors for the Sensirion sensor.
  3. Documentation and build instructions – we realize that we need to put something together which will be easy and safe enough to use in an actual clinical setting. As we scale up our implementation, all will be shared. This will include reliable places to source everything. This has been a major issue but vendors like Sensirion (sensors) and Adafruit (gadgets, gizmos, and Raspberry Pis) have stepped up to support us; this is an amazing testament to the world rising together in the face of catastrophe.

We’ll do our best to keep you up to date as everything changes in rapid succession. We hope that others will leverage our work so as busy as we are, please please please reach out with questions. We’re all in this together.

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.