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Comment by jylam | Hacker News Reader

I'm not a ventilator specialist, but this is gaining some traction and I fail to understand how it really helps. Is the ventilator shortage just a mask shortage ? Isn't there a quite complicated machine plugged to the mask ? With complex valves and a motor and pressure sensors and alarms and whatever ?

Again, I don't know what I'm talking about.

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There has been some discussion on 3D printing medical ventilators on the local hackerspace mailing list. One of the participants used to work at a company which builds those and made similar points:

There are different systems, one are the C/VPAP which are only for ventilation during sleep, avoiding a closure of the pharynx by increasing the pressure to a certain maximum value. Some of those have parameters also taking care of the patient's breathing pressure etc. but in general can only help for "better sleep" – if they fail, then you have a bad sleep but won't die.

The systems they use in hospitals are the complex machines you describe: they have battery power, measure the flow of breath, have alarms etc. Even here they distinguish between "supported breathing" and "keeping alive", i.e. in the former case the machine helps you to breathe while the second takes care of breathing for you.

In Italy, a doctor asked for a replacement part of their ventilators which was then 3D printed – the valves mentioned in the article. This seems to have led to a surge in people now trying to build, design, etc. ventilators which can essentially be build anywhere, to combat supply chain shortages.

Again: You are right, medical ventilators are a tricky business and difficult to build. But in this case, the ventilators seem to be there, they just need the valves, which can be printed. And they put up a huge disclaimer that patients need to agree to use unapproved devices.

A German article covering this is [1].

[1] https://www.deutschlandfunk.de/kreative-loesungen-in-zeiten-...

Apparently doubling the pressure allows two or maybe more patients to be hooked to the same ventilator with a kind of T-junction. In this situation you would only need an extra mask.

Non Invasive Ventilation is the preferred mode to assistant patients with the lung pathology COVID creates. This requires higher than normal lung pressures for oxygenation as the concentration of O2 can be detrimental to the lungs causing a worsening. The extra pressure means a lower concentration of O2 is needed to help the patient.

Intubation adds more risk to the patients lungs recovering because the volumes of air moved in an out can also cause injury; as the lungs are no longer moving as well with the increased fluid COVID patients experience. A full featured ventilator is not a silver bullet, it is a sign that things are very serious for the patients lungs. The shorter amount of time on the ventilator the better, which also means no ventilator unless absolutely necessary.

Using a mask like this does the basics, but we do have to rely on the patient to move their own air volumes in and out. Often they are able to do this, so this mask could provide real benefits.

The bubble helmets you can see in Italian hospital footage have been shown in an 2016 study to reduce the need to intubate and put patients on a full featured ventilator. The caveat being the COVID pandemic experience will glean a lot more insight into keeping patients from being intubated and off of full featured ventilators.

Seems like in times of need ventilators can be rigged to support multiple patients:

https://onlinelibrary.wiley.com/doi/pdf/10.1197/j.aem.2006.0...

https://www.youtube.com/watch?v=NER2h9STy7Q

Masks and valves and tubing are much less durable goods than the ventilator itself; some of them wear out, some of them become biohazards after use, etc. So there's both a shortage of the parts required to keep existing ventilators in continued use, and of the machines themselves.

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