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Open Source Ventilator
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Canis Dirus Leidy:
I would like to draw attention to one more thing. All these wundergerätes  without a qualified doctor are useless and simply dangerous.  Because (AFAIK) humans have several mechanisms for breathing regulation, and by the time when artificial lung ventilation is required, these regulators work and interact in non-standard mode. And now we have threaded a tube into the patient and we are driving into the lungs a non-standard mixture with pressure profiles other than atmospheric.
Blitzschnitzel:

--- Quote from: Domagoj T on March 30, 2020, 06:32:08 am ---This and all others open source ventilator movements (and I've seen several in the last few days) is exactly the same story as with every other open source project - multiple different designs, every one different, not compatible with each other, and not a single one a complete solution. All that is needed is for them to be offered as "some assembly required" and for the ICU nurses to figure out how to compile the firmware through the command line.

--- End quote ---
Dude those hand operated ventilators are standardised, come with all the connectors and are approved. If you put a nurse next to a patient’s bed and let her or him hand pump the thing full time, that would be a legally approved way to ventilate a patient. The peak pressures and minimum pressures are regulated by the valves in the Ambubag and you can rout in the correct oxygen mix.
All the machine has to do is squeeze a bag at a set rate and make a lot of noise if it fails. This way you can free up the more sophisticated machines for the complicated and more severe cases.
The reason those projects you've seen in the last few days look unfinished is because they are unfinished. They started in the last few days.
We are working on a sheet metal box which squeezes a bag and you turn the dial how often you want that to happen per minute. No firmware compiling required by the nurse.
Domagoj T:
Those things are for temporary usage. Device for long term usage are considerably more complicated (for a reason).
You have also not addressed the main criticism I brought up - there are existing, better solutions. Use them.
jogri:

--- Quote from: pipe2null on March 30, 2020, 03:01:09 am ---Hmm.  My current thought is passing the exhaled air through a filter and illuminating one or both sides of the filter with UVC.  Provided the light penetrates deep enough on/in the filter to reach trapped viruses, the exposure time would be significantly increased since the virus is trapped and you might not need as intense a UVC source.  I'm not sure if generated heat from the lamp would help keep the filter dry, or extend the useful period of the filter itself.  I only mentioned the air purifier thing since it's an off the shelf product that includes some type of filtration with UVC.  Plus a fan providing a little negative air pressure helps make sure contaminated air gets where you intend it to go.

--- End quote ---

Bad idea, that won't work for a number of reasons:

1) UVC doesn't penetrate filters as they are designed to act like labyrinths for incoming air-> extremely high surface area without line of sight to the UV source
2) UVC degrades plastic at an alarming rate, your filter is not going to last long
4) heat+oxygen can also degrade plastic -- Why is that important? They are going to be used as a last resort, and at that time the hospital will probably only have critical patients. Straßburg is nearing this stage, and everyone they have on ventilation needs 50-100% O2 in the air to survive. A O2 level that high (combined with heat) will just melt your filter, as soon as one tiny hole starts to form inside your filter more air is going to rush through that hole as it is the past of least resistance ->more air ->bigger hole->filter gone


Btw, the same problems apply for ozone: That stuff is extremely reactive and toxic as hell. And it stinks like crazy, so you just can't vent the filtered air outside without giving everyone inside the hospital a headache (lovely stuff, isn't it?).

But lets come back to the UVC idea: Hospitals already have UVC sources in the kW range, they are used for sterilizing operating rooms. Basically just a very big lightbulb (mercury vapour lamp) on wheels. Might be usefull, but you could also use the Straßburg approach to have a negative pressure inside the rooms and have your vent system deal with the contaminated air.
Blitzschnitzel:

--- Quote from: Domagoj T on March 30, 2020, 10:42:52 am ---Those things are for temporary usage. Device for long term usage are considerably more complicated (for a reason).
You have also not addressed the main criticism I brought up - there are existing, better solutions. Use them.

--- End quote ---
They are more complicated for versatility and a simple forced ventilation system can free up sophisticated machines where versatility is needed, like assisted ventilation. We are following the UK's "Rapidly Manufactured Ventilation System" requirements and are getting advised by health professionals. Yes there are better machines, but if you follow the news there aren't enough and it is going to get worse before it becomes better.
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