I have a collection of motors, gears, sprockets and chain, wood, hoses etc, so how hard can it be to make a basic mechanical ventilator?
I have a few questions, basically I need a mechanical design brief. I'm talking basic 1950s tech here, no computers/embedded processors, just mechanical.
1) How many breaths per minute?
2) What volume?
3) What pressure?
4) How does the air get out of the patient's lungs again? Do I need a phased outlet valve or would a correctly size orifice do?
5) how does the tube "connect" to the patient?
I'd expect that the trickiest part might be making something that can be safely lodged down somebody's throat for weeks and sterilised effectively between patients (if necessary), but I'm not any sort of engineer (nor am I even that practical).
It's a good idea, though, if a lot of practically-minded tinkerers can be harnessed to help out with the shortage of PPE.
Re: DIY ventilation design.
Posted: Tue Mar 17, 2020 1:08 pm
by Gentleman Jim
An endotracheal tube is a flexible plastic tube that is placed through the mouth into the trachea (windpipe) to help a patient breathe. The endotracheal tube is then connected to a ventilator, which delivers oxygen to the lungs.
I think it's James May who does those "take it apart and see how it works" programme?
Give him one, he and a team takes it apart on camera, all live on TV or YouTube. People gather on a forum afterwards, saying my factory's shut down right now but I could open it up and make that bit, haven't a clue about anything else.
Or do a hospital bed, showing all the components - one small company says it can make the structure and wheels but nothing else, another says it can do the motor for the tilting mechanism but can't do a controller, another says it saw the bit about how the controller was made and they already have every component in stock except for the plastic case, and so on.
I'd expect that the trickiest part might be making something that can be safely lodged down somebody's throat for weeks and sterilised effectively between patients (if necessary), but I'm not any sort of engineer (nor am I even that practical).
I think those bits get thrown away between patients rather than sterilised, and I thought that the valve? connector? whatever it is they were 3D printing in Italy was in short supply because they can only use it for 8 hours at a time even with the same patient.
Some devices create aerosols too* which you definitely want to avoid like the, er *winces*, plague right now, so you'll have to make sure what you're knocking up in the garage doesn't do that or you'll be making things worse for NHS workers.
*Hence a statement from the Royal College of Obstetricians and Gynaecologists statement saying "... the use of Entonox (gas and air) may increase aerosolisation and spread of the virus, so your maternity team will discuss all the options with you in early labour to ensure you are aware of the pain relief options available to you."
*When my first wife was giving birth, the midwife gave her the cylinder of Entonox (home birth. During one contraction, the cylinder was hurled across the room, narrowly missing my head
*When my first wife was giving birth, the midwife gave her the cylinder of Entonox (home birth. During one contraction, the cylinder was hurled across the room, narrowly missing my head
Spoiler:
She was supposed to breath it, not stick it up there for baby!
Re: DIY ventilation design.
Posted: Tue Mar 17, 2020 4:48 pm
by nekomatic
For anyone with ideas or resources to contribute, not just on ventilators:
Realistically, I do not think amateurs are going to accomplish a damn thing except perhaps clogging communications.
Given we knew this was coming, why the f.ck were blueprints sent out now, not months ago? Why are they talking about plans for a basic ventilator now, not paying to have one developed months ago, or better yet, having a plan on the books for whenever it is needed as a long term measure?
Realistically, I do not think amateurs are going to accomplish a damn thing except perhaps clogging communications.
Unless you have industry standard CAD and CAM software and are familiar with the available production facilities, you're likely just clogging channels. IME of designing stuff for research (and this part likely carries over to any prototype) there are usually bottlenecks in turning designs into manufacturable and assemblable models using appropriate materials, obtaining raw materials and standard parts, and in programming the available production machine tools.
Re: DIY ventilation design.
Posted: Wed Mar 18, 2020 12:15 pm
by raven
It occurs to me that DIY masks are probably a lot easier to make than DIY ventilators. Are we asking manufacturers to switch to making masks and gloves and other items for personal protection or do we have enough of those?
Re: DIY ventilation design.
Posted: Wed Mar 18, 2020 1:37 pm
by Pucksoppet
I wish the rules were clearer with regard to suspension (or not) of patent enforcement.
There is probably a good reason, but I could not find an answer by a swift Internet-search.
What are the reasons that an Iron Lung couldn't be used for ventilation?
My guess is that they could be simpler to manufacture than a 'down-the-trachea' positive-pressure ventilator, and likely easier to sterilise.
But they might be useless.
Re: DIY ventilation design.
Posted: Wed Mar 18, 2020 5:37 pm
by JQH
Iron lungs were used for patients whose chest muscles didn't work due to polio. Their lungs were fine and they breathed ordinary air. In the case of Covid and similar diseases patients lungs are damaged and they need oxygen enriched air.
