This is an Open Source project I created to help people build a more effective ventilator. The control system is the biggest hurdle for most people building a ventilator.. Most ventilator builds I've seen just run on a fixed cycle or timer, and feed a breath regardless if the patient is inhaling or exhaling. Unless the patient is sedated or paralyzed, these simple ventilators won't be effective. They need a more sophisticated control system, and that is what this project is about.

The mechanism that squeezes the bag can take on any shape (squeezing arms, cam lobe, belt cinch, weights and pulleys..), these are all compatible with the control system plans I'm providing.

This control system adds:
- Breath sensing functionality, so the ventilator synchronizes it's breath when the patient inhales, allowing the patient to breath naturally without timing their breath with the machine.
- Ability to change the volume, rate, and speed of breathing (T.V. BPM, I/E ratio)
- Measure diagnostic pressures (Peak, Plateau, and Peep)
- Turn on an Alarm if something goes wrong (pressures exceeded, hardware fault...)

Note: I have no experience in the medical field, and am certainly not an expert in ventilators, this is my first attempt.





This ventilator control system uses a PLC (programmable controller), pressure sensor and position sensor to upgrade a simple mechanical ventilator into an Assist Control Ventilator. Since this is an open source project, the PLC code and drawings are located here:. http://www.etischer.com/ventilator

The project is pretty much complete at this point, as it seems to be working pretty well. There are obvious things that need to be done to bring it to 100% (support arms to hold the Ambu bag in place, additional finger tips to widen the contact area of the bag, these are simple things to add), but functionality wise it seems to be working. I'll continue to update the webpage with the latest PLC code and drawings.

I machined the mechanical parts on my Shapeoko CNC router, and desiged the controls hardware & software myself. I have quite a bit of experience with the electrical and software portion of the project (Sr. Staff Controls Engineer Tesla (retired)) but no experience with medical devices, ventilators, or CPR equipment.

List of resources I've used:
https://e-vent.mit.edu/mechanical/
   • Ventilator Modes Explained! PEEP, CPA...