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Professional Ventilator Design Open Sourced Today By Medtronic
Medical device company Medtronic released designs for one of their ventilators to open source for use in the COVID-19 pandemic. This is a laudable action, and there is plenty to glean from the specs (notable is that the planned release is incomplete as of this writing, so more info is on the way). Some initial reactions: medical devices are complicated, requirements specifications are enormous, the bill of materials (BOM) is gigantic, and component sourcing, supply chain, assembly, and testing are just as vital as the design itself.
The pessimist in me says that this design was open sourced for two reasons; to capitalize on an opportunity to get some good press, and to flex in front of the DIY community and convince them that the big boys should be the ones solving the ventilator shortage. The likelihood of anyone actually taking these specs and building it as designed are essentially zero for a variety of reasons, but let's assume their intent is to give a good starting point for newer changes. The optimist in me says that after what happened to California over the weekend with 170 ventilators arriving broken, it might be nice to have open designs to aid in repair of existing non-functioning ventilators.
The design details released today are for their PB560 model, which was originally launched in 2010 by a company called Covidien, before it merged with Medtronic, so we're already starting with a device design that's a decade old. But it's also a design that has proven itself through widespread use, and this data dump gives us a great look at what actually goes into one of these machines.
As one might suspect with a medical device, there are documents. Lots of documents! Among those supplied are: "Requirements Documents", "Electrical Schematics", and "Manufacturing Documents" and far more still remain:
Despite it being a dump of 53MB, there's quite a bit missing if you were trying to build this machine. However, Medtronic did mention in their press release that "...software code and other information will follow shortly." so there are more details on the way.
[...] we suspect that the amount of work that would be required to spin up assembly of this particular product is more than could be accomplished in the amount of time available, and the resources that would have to be mobilized are probably the same resources already working on building medical devices for other designs. The documentation around the release says any products released based on this are only to be used for COVID-19, so if anyone does manage to take this and use it to start production in a timely manner it will be both incredibly helpful, and super impressive.
(Score: 3, Informative) by hemocyanin on Tuesday March 31 2020, @04:18AM (7 children)
The usefulness of manual respiration devices (ambu bags): https://www.youtube.com/watch?v=1goz1l28kUQ [youtube.com]
Automating a manual ambu bag: https://scitechdaily.com/mit-posts-free-plans-online-for-an-emergency-ventilator-that-can-be-built-for-100/ [scitechdaily.com]
You can attach manometers to make sure you don't overpressurize the lungs as well as an oxygen supply to provide pure O2. There may be a middle ground of effectiveness between an automated manual ambu-bag and a full on respirator. The former can be built pretty quickly for next to nothing.
For greater automation, there are manometers for arduino which could be used for alarms or setting the period, duration, and volume the ambug is pressed, though it appears the ones on breakout boards are a month away from having in hand: https://www.amazon.com/Breakout-MPXV7002DP-Transducer-Differential-Pressure/dp/B01MCVOZJO?ref_=fsclp_pl_dp_2 [amazon.com]
The bare chip is available though: https://www.digikey.com/product-detail/en/nxp-usa-inc/MPXV7002DPT1/MPXV7002DPT1CT-ND/3524215 [digikey.com]
(Score: 3, Interesting) by anubi on Tuesday March 31 2020, @08:36AM (4 children)
Never underestimate the end of an air tube poked just so deep in a bucket of water as an overpressure relief.
Under the bed. You do not want to make a siphon.
https://duckduckgo.com/?q=inches+of+water+to+PSI [duckduckgo.com]
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by JoeMerchant on Tuesday March 31 2020, @01:25PM (3 children)
That's a great overpressure relief system, however, who are you going to get to squeeze the bag 24-7 for 2 weeks? A rotating shift of 4 volunteers means 4 more people heavily exposed to the virus - it's probably easier/cheaper to build a mechanical vent than all the PPE required to do volunteer bag pumping safely.
🌻🌻 [google.com]
(Score: 1) by anubi on Tuesday March 31 2020, @09:43PM (2 children)
I was thinking if one was going to build a mechanical motor-driven bellows, linkage adjustable for tidal volume variance, motor speed variable as well, I would probably have something like this beneath the bed to insure my apparatus did not overpressure the patient.
You don't wanna pump the tummy up. It'll blow its contents back up, right into the lungs. Those digestive fluids work wonders there.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by JoeMerchant on Wednesday April 01 2020, @12:52AM (1 child)
OP is right, some of the Medtronic data dump is "flexing" on all the "ventilators are so simple, my grad student could design one" crowd. What's in that dump is a complete set of requirements - which is actually the hard part of designing any medical device, getting things like use cases and overpressure relief valves properly spec'ed, etc. All in all, I think it's honestly less a publicity stunt and more a genuine effort at educating those who are making ventilators - sharing IP the way Mercedes shared their energy absorbing crumple zone tech.
🌻🌻 [google.com]
(Score: 1) by anubi on Thursday April 02 2020, @12:32AM
When I looked at the specs...I saw a problem of calibration using readily available known accurate references. Also such a critical valve has to be as reliable as possible...but cheap to make.
I have worked around cal labs, and we were always looking for ways to verify calibrations of other equipment by using known good references, NIST, known physical constants, and the laws of physics.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 4, Interesting) by TheRaven on Tuesday March 31 2020, @01:56PM (1 child)
sudo mod me up
(Score: 2) by JoeMerchant on Tuesday March 31 2020, @04:38PM
Unfortunately, as has been explained to me, among those who need hospitalization COVID-19 causes alveolar collapse, and different patients need different vent settings to balance their particular state of compromise - enough to get them the gas exchange they need (CO2 removal being more problematic than O2 supply, when pure O2 is available), while not overly stressing their already damaged lungs.
🌻🌻 [google.com]