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OT - how does a ventilator work?

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  • OT - how does a ventilator work?

    I'm posting this here because you guys are the best source I know for practical knowledge:

    I've been reading about the lack of ventilators and also that there's some students in Ireland developing an open-source 3D printed one. How complicated are they, really? The small amount of information I've found seems to say that it's only an air pump but I had previously thought that they also introduced a small amount of pure oxygen, too.

    You know where I'm going with this, so is making one possible?

  • #2
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    • #3
      Making one is possible. It was mentioned in the thread about volunteering to help manufacture medical gear. A long time ago it was basically a mechanically operated bellows with a one way valve to allow you to exhale. It was likened to a modern CPAP machine. The major difference between CPAP and Ventilator is probably that the Vent can be used when intubated (a tube that enters the airway through the mouth. The CPAP machines I've seen are meant to be used with a mask.

      A DIY vent.
      The Pandemic Ventilator: Assembly instructions for a DIY Ventilator prototype.This could be useful in an Avian Flu pandemic.Constructed with commonly available components.Many of us modify, hack, re-purpose, and DIY to save money, build something unique, create art, or show…

      At the end of the project, there is a profound difference between spare parts and left over parts.

      Location: SF East Bay.

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      • #4
        Well, you have me thinking. I have a CPAP machine that I am no longer using. I wonder if any of the hospitals, local or otherwise, could use it. I think I will check that out.
        Paul A.
        SE Texas

        And if you look REAL close at an analog signal,
        You will find that it has discrete steps.

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        • #5
          Does anyone know the volume of air that would get "pushed" to the patient? I have everything on site I would need to build one. The bladder or billows I could make out of PVC material I have. The welding machine for the PVC I have already built so the would be the easiest for me. A simple PLC a couple of limit switches, throw in an air cylinder to operate the billows and done.
          Location: The Black Forest in Germany

          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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          • #6
            Cool instructables article. Construction of the machine looks easy enough but I don't know squat about electronics and programming. If this were to happen someone who knows what they're doing would have to figure out where to get the individual pieces and post more in-depth technical stuff

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            • #7
              Did you try google? There is plenty of info out there. The wiki page is an excellent place to start. It gets quite complicated, and the effectiveness varies greatly. The modern machines are amazing. They're smart. I watched a respiratory tech use one on a family member after open heart surgery. They have modes where they actively wean the patient off of mechanical ventilation and back to breathing on their own. I gotta say, when I watched that process, I was in awe of what that machine did, and how cool the technology was.

              I hear Israel is buying thousands of them right now. I am sure there are a limited number available on the market. I wonder if our federal government is competing to buy them, or if they're just letting local hospitals try and source them on the international market?

              The Fed needs to step up and do the defense powers act, which they have not actually done. They need to formally request manufacturers produce critical products to an exact specification, in a specific quantity, and negotiate price, etc. Especially for a complicated medical device like a ventilator (obviously needed in different version - basic designs and more sophisticated designs). There also needs to be documentation for the product, or it needs to be an exact copy of a version that is widely used and familiar. Saying on TV "just make it" is not anywhere close to sufficient. That'd be like the government in WWII telling companies to "just make us bomb sights" without giving them the design specifications, etc. Businesses cannot spend millions making stuff only to have the fed say that isn't quite what we need so you won't get paid.

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              • #8
                Scroll down to the post by peak4. Title ventilator production coronavirus
                https://www.model-engineer.co.uk/for...64&p=1#PostTop

                This post put the project in perspective for me.
                If we get it wrong, the ventilator can cause barotrauma. At its most extreme we blow a hole in the patient's (diseased) lung and then we have a tension pneumothorax, which is rapidly fatal unless we stab the chest and insert a drain to allow the lung to re-expand. More often, the barotrauma causes microscopic damage that delays or prevents the sick lung from healing. The sensors also alert us if the tubing kinks or disconnects. Unchecked these simple things are quickly fatal.

                Paul
                Last edited by PointFive; 03-23-2020, 11:39 AM.

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                • #9
                  If we get it wrong, the ventilator can cause barotrauma.

                  I'm not suggesting going to a children's hospital and making these the first line of defense. This would be if you were, for instance, in a nursing home and no ventilator was available.

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                  • #10
                    Yes it comes down to this, die or at least try a home brewed ventilator. Me I would try to build one if none were available.
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #11
                      I can see someone making one of those for a relative or close friend and taking the chance of using it if a proper ventilator is not available. Making one for yourself may be possible if you do it in advance.

                      BUT, unless things get a lot worse, I do not think any hospital or other care facility would take the chance of even having one on the premises. After the first patient dies on one of them, the lawyers would have a field day.

                      I have said it before and I will say it again, if you want to help in this shortage, it needs to be done through a company/manufacturer who is already in the business and who has the needed knowledge AND the absolutely needed insurance. If you want to help, contact such a company and see what you can do to help THEM make them faster. And cheaper.

                      Just one example of what could GO WRONG. I looked at the instructions. They say the common pipe fittings are assembled with Teflon tape. I have seen the inside of a Teflon tape joint and small shreds of that tape are a common thing. If one of those small shreds of tape were to get in the patient's lungs and needed to be removed, possibly surgically, you have a really bad situation. And the possibility of law suits even if the patient survives. How many of us are really proficient at assembling a joint with Teflon tape and absolutely not creating such a problem. How many of you are even ready to admit that this or any one of many other things could even be a problem. I can hear the comments saying that this should not be an impediment to making and using these devices that could possibly save some lives. A company in the medical field probably does not use Teflon tape or if they do they probably have a strict procedure for assembling the joints with it. Or a filter in the line after such joints. But just how is it installed without Teflon tape? And is that method safe? That's just one thing that could go wrong with a unit made by someone with no experience in the field. As I said, when the dust settles, the lawyers WILL have a field day. And it will be YOU and all of your personal assets at the focus of such a legal battle.



                      Originally posted by danlb View Post
                      Making one is possible. It was mentioned in the thread about volunteering to help manufacture medical gear. A long time ago it was basically a mechanically operated bellows with a one way valve to allow you to exhale. It was likened to a modern CPAP machine. The major difference between CPAP and Ventilator is probably that the Vent can be used when intubated (a tube that enters the airway through the mouth. The CPAP machines I've seen are meant to be used with a mask.

                      A DIY vent.
                      https://www.instructables.com/id/The...ic-Ventilator/
                      Last edited by Paul Alciatore; 03-23-2020, 02:30 PM.
                      Paul A.
                      SE Texas

                      And if you look REAL close at an analog signal,
                      You will find that it has discrete steps.

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                      • #12
                        Paul, I understand your concern and I agree that this is not something to be taken lightly. However, I'm 55 and my boy is a teenager. If it comes to choosing between me and a man half my age with preschool-age children the proper ventilator would and should go to him.

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                        • #13
                          Things get bad enough and everyone will be thrilled to have local shop-made ventilators available. A better standardized design, with DIY grade electronics, needs to be generated. Optimally, you could simply plug an arduino with a software download into a phone and use an app to control it. Use what's commonly available! And take advantage of small mass production methods like vacuuforming and CNC, not slow as crap 3d printing.
                          Location: Jersey City NJ USA

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                          • #14
                            One of my motorcycle friends is a hospital pharmacist and pretty good with electronics. I've got him looking at it now.

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                            • #15
                              I wish there was more interest in this thread. What is it with you americans and running to lawyers the whole time.?Africa is not for sissies.We may need lots of homemade ventilators in a very short time. Could one not be made with a linear actuator squashing a bellows. I dont really understand how they function.

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