Here’s another example of something that really helped.
They made a much needed part in volume and those parts are being used to save lives right now! I feel like we cannot just make this up on our own, wed need to include the medical community. How can we reasonably do that?
It definitely seems like there’s a lot of sensors and controls on these machines. Making a functional pump is one thing, but how do you communicate to medical workers the status of the system and patient?
It can be a pretty involved process if intubation is required. And I don’t know if COVID-19 complications could be alleviated without intubation.
This is a nice technical video explaining how non-invasive ventilation works. It looks like CPAP is probably not useful here, but maybe BIPAP could be. This makes me wonder if an air compressor could be used as the pressure source to a bunch of small dual pressure regulators with a valve to switch between low pressure and high pressure. This eliminates the need for a bunch of separate motors.
Learning more. It looks like all ventilation is positive pressure, so I’m still thinking an air compressor could be used as a pressure source. One key is that the air needs to be humidified and warmed before entering the body when invasive (intubation) ventilation is used.
I’ve sketched out a simple mostly mechanical design that I believe could be be easily constructed assuming the hospital has access to the intubation supplies and just needs a mechanical cycling air pump. I’m still doing more research so this might be useless or wrong, but if you need a dual pressure cycling air system, I think it could be a simple manifold with mechanical pressure adjustment for high and low pressure settings, and a timing or sensor based circuit to alternate between high and low pressure. I’m going to work on a quick YouTube video to explain what I’ve found so far. At this stage I feel confident that a simple system could be made easy to produce, but I need input from medical professionals on whether more ventilators are really a bottleneck and if so if what I’ve come up with would have any value.
See the diagram below. I will come up with a video describing it starting with a simpler block diagram in an hour or two.
I watched your video on youtube and have since reached out to a friend who works as an anesthesiologist to ask him a few questions about ventilators.
Most ventilators used these days are high tech with automatic lung capacity pressure gauging, and a multitude of sensors. Repairs must be made by technicians from the manufacturing company.
Roughly twenty years ago hospitals used what are called Volume Dependent ventilators which used a rotary dial to adjust the volume of air used for each patient and were operational from the volume source alone. they contain moisture filters that are discarded when saturated. The power of the air under pressure exceeded the need of human lungs. Adult lungs need anywhere from 15-25psi, and this air typically is piped throughout hospitals (not air tanks) and MUST be purified and filtered.
I have more info but these are the most important parts for a desperately needed functioning ventilator.
I look forward to discussing more with you.
Here’s another video increasing a single operational ventilator’s capacity:
Wow great information Xandra! Thats a useful video. It makes me think if the 3D printing community could have high impact just printing three way and four way adapters. Or maybe the hospitals have enough of those fittings she used in the video? One thing to note - I think you mean 15-25 cm of water, not 15-25 PSI? 25cm of water is about 0.3psi.
Regarding emergency ventilator designs, I’ve found a few groups online that are working on them. I should find appropriate links to add to this sub. But I do get the feeling that in the USA some big name manufacturers may be able to provide the ventilators we need. Not sure.
I’ve found it a bit slow to get traction on open source collaboration here. But according to you and the UK specification, volume control or pressure and volume control seem mandatory. I’ll have to think on how that can be done. Then perhaps I can work with some of the other groups to come up with something. I don’t know if I can help get something functioning for the current pandemic, but I am really starting to think we need working open source designs for this kind of technology for emergencies like this.
Last night I printed the face part of it, with the filter holder printing now.
On my $300 resin printer it takes 9.25 hours to print this part, plus another 45 minutes for the filter holder. So thats 10 hours per mask, or 2.4 masks per day maximum if I never stop it from running.
It is also not recommended to use normal 3D printer resins as they contain chemicals that irritate the skin and can cause allergic reactions. There is a supplier in Barcelona offering a discount of some biocompatible resin for anyone that wants to print masks:
They offer a 20% discount on top of the currently discounted rate if you email them and ask for the code.
Real Engineering has done a great video on these efforts for low cost ventilators.
Designing a suitable unit is difficult, and most of the DIY designs on the internet would be of little use for COVID patient treatment. Accurate sensors and microprocessors are needed. It would be good to know how the cheap design from India mentioned in the video actually functions, and whether it is suitable for COVID treatment,