From a quick search, here are similar discussions:

https://www.instructables.com/id/The-Pandemic-Ventilator/ which links to: https://panvent.blogspot.com/

https://www.projectopenair.org/

https://github.com/jcl5m1/ventilator HN discussion --> https://news.ycombinator.com/item?id=22599415

Learning about Ventilators: https://medlineplus.gov/ency/patientinstructions/000458.htm

https://www.reddit.com/r/medicine/comments/fgmsrh/open_sourc...