[HN Gopher] MakAir: Covid-19 ventilator with a Raspberry Pi
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MakAir: Covid-19 ventilator with a Raspberry Pi
Author : mtmail
Score : 90 points
Date : 2021-01-07 12:34 UTC (10 hours ago)
(HTM) web link (blog.senx.io)
(TXT) w3m dump (blog.senx.io)
| sahin wrote:
| Great work. I am a big fan of Raspberry pi. For hospital
| environment does raspberry pi have the reliability, stability and
| durability for health use case for real life environments?
|
| it will be so budget friendly, i am sure many hospitals in the
| world can use it...
| tonymet wrote:
| there's no guarantee in linux when or if your code will
| execute. it works well for consumer apps but you can't use
| linux eg to pilot an airplane or for life support
| baptistejamin wrote:
| It's why there is a second board to handle critical tasks:
| https://news.ycombinator.com/item?id=25671318
| mbreese wrote:
| My initial reaction was to say that there is no way the RPi
| would be reliable enough for clinical purposes. _However_ ,
| from the schematics, it looks like the RPi is only used for
| displaying the airflow curves and not used to control the
| ventilating. A microcontroller is used for that critical
| function.
|
| If this is the case, then this would make the reliability much
| better and there is a chance it could be useful to many places.
| If the SD card on the Pi dies (which, if they are logging the
| data to SD and not RAM, is a likely event), then they can have
| spare SDs available as part of the standard operating
| procedure. It's not ideal, but so long as the main
| microcontroller is functioning, the display could be considered
| non-critical. Although, ICU staff might disagree...
| baptistejamin wrote:
| It's why there is a second board to handle critical tasks:
| https://news.ycombinator.com/item?id=25671318
| mbreese wrote:
| If I could ask -- I saw a LoRA circuit mentioned in the
| schematics... what is that used for?
| pp-ir wrote:
| Short answer is no, I don't trust Rpi for vital tasks.
|
| Long answer : In this project, Raspberry is used to display
| curves and set some parameters. The core (ventilator algorithm)
| is implemented on the STM32F411, there is just a serial link
| in-between.
|
| The STM32 also monitor the Raspberry... If there is no
| heartbeat on the serial link, the STM32 shuts down the power
| supply of the raspberry, and ventilation goes on.
|
| The fact is that it never happens yet during our tests (4
| months uptime now for some devices). The ArchLinux is
| restricted to the bare minimum, and the Rust app do not
| overheat the CPU. Is it by chance, or not ? Before any MTBF
| conclusion, you need thousands of units running during
| months...
|
| On another project of medical datalogger, I also put a little
| arduino as hardware watchdog. If no heartbeat of the main
| application, it just resets the Rpi.
|
| I also use industrial SD card, which are far more reliable and
| provide SMART informations. See another article on this
| subject: https://blog.senx.io/a-10-year-warranty-thanks-to-iot/
| craftinator wrote:
| This is good systems design. I've made a system with a
| similar design (RPI for display and UI, one STM32 for
| hardware control, another as watchdog) for an industrial
| marking system, and it's run almost daily for 3 years without
| any issues.
|
| The great thing about the Pi in this case is that it's non-
| critical, and if it ever does die, you spend $35 and put in a
| new SD card.
| pp-ir wrote:
| As soon as ANSM (french equivalent of US FDA) hears
| "linux", "wifi", "connected", they see a scary green
| monster...
|
| And to be honnest, I understand their point. How can you
| certify Linux ? So much code behind... It is not a car
| multimedia center, it is a ventilator, a class III vital
| device.
|
| In this project, what was really impressive is the gap
| between the bare minimum (a 4 lines lcd screen + a few
| buttons + a pressure sensor, and you can make people
| breath), and the doctors expectations (curves, flow meters,
| statistics, O2 sensors...).
|
| This is the same for lots of activity: experts cannot work
| with basic tools anymore. Only High level experts still
| can.
|
| Conclusion: do not work with high level experts to build
| your specifications. Also listen to normal experts and
| doctors that needs more UX assistance.
| MayeulC wrote:
| Thank you for this valuable insight.
|
| Do you think relying on something like a hospital-
| provided tablet would have worked? Was this considered?
|
| I mean, having that many screens may be a bit redundant,
| if you can have a single high-quality one. That said, I
| understand it introduces some complexity due to wireless
| protocols, paring with the right ventilator, etc.
| pp-ir wrote:
| You're welcome.
|
| In our initial requirement list, it was designed to be
| used in temporary hospitals (any public hall for
| example).
|
| Screen convergence is not for now in hospitals. Behind
| one sensor, there is one company that sells its monitor
| with the sensor. Some old well known sensors now converge
| to one monitor (philips, edwards life science...), but
| there is a still one screen for every other functions.
|
| Gathering data (when the constructor made it available)
| is a mess... look at HL7 specs! To build a medical
| datalogger, you sometimes must interface to an analog
| output (it is part of my job).
|
| By the way, most monitors runs windows CE behind. Which
| is also a problem now:
| https://www.integrasources.com/blog/windows-ce-end-of-
| life-m...
| PoachedSausage wrote:
| Why use the Rpi at all (Nothing against them, I have a few)?
| If the Pi is just writing graphics to a screen, why not
| handle that directly with the STM32? Running an RTOS, it
| should be able to manage a low priority GUI task along with
| the real-time ventilator tasks.
| DoingIsLearning wrote:
| I assume when you refer to 'serial link' you mean that you
| are using Rpi UART interface to communicate with the STM32.
|
| I can see the convenience of using UART but as a very
| cautionary advice, hospital environments are electrically
| quite harsh in terms of EM noise. A serial line even a short
| one can absolutely suffer from interference.
|
| You already made it relatively fail-safe with the
| heartbeat/watchdog but please consider upgrading your design
| to use comms with a differential signal, anything like CAN or
| even RS-485 in that Rpi/STM32 link would be a significant
| improvement.
| pp-ir wrote:
| I'll be very happy for my industrial projects if BCM2711
| come with CAN or RS485 built-in, but for the moment, there
| is nothing planned by Raspberry...
|
| A low speed 115200 baud link does the job, with applicative
| CRC on both side to be sure there is no corruption.
|
| My method to test communication robustness: I inject pulses
| through a capacitor directly on the UART lines. I did it on
| this project, no problem. The four bytes CRC32 prevents
| random EM noise errors.
|
| STM32 telemetry code is here:
|
| https://github.com/makers-for-life/makair-
| firmware/blob/mast...
|
| Pierre, author of the article.
| ska wrote:
| I think the problem OP is referring to is that if you
| were proposing this design for a approved medical device
| for use in say US & EU, you might have trouble passing
| e.g. 60601 because of the communication channel. I
| haven't looked over the design in detail but EMI etc. can
| be quite tricky to manage in this sort of device.
| pp-ir wrote:
| You're right. We will see. EMC tests are part of our
| program.
| ska wrote:
| Are you working with a test house? They can really help
| pin down issues quickly.
|
| Sounds like a fun project!
| flowless wrote:
| If your embedded stack supports USB you could use CDC ACM
| for possibly more robust comms (checksummed by USB, no
| need for RTS/CTS).
|
| Also there are CAN hats for rPi (SPI) or USB<->CAN
| bridges (using slcan protocol and Linux driver).
| baptistejamin wrote:
| You can also find the project on GitHub:
| https://github.com/makers-for-life/makair
| chrisseaton wrote:
| I thought everyone decided we didn't need a vast number of
| ventilators like we thought we would? There was a huge panic for
| a week last March and a lot of random companies were going to be
| making them, then it just seemed to go away.
|
| Does anyone know if we managed to ramp up normal production or
| there was some other reason it stopped being an issue? Or maybe
| the issue didn't go away just the media coverage and they're
| still trying to use ad-hoc ventilators?
| coding123 wrote:
| I've heard directly from doctors that the entire ventilator
| thing was a huge mistake and ended up causing more death.
| Treatment is now more focused on statins. The covid shell is
| basically in your blood clotting everything up - it's a huge
| ass fat cell that is killing people. Take aspirin.
|
| Also help your immune system before and after you get covid by
| taking Vitamin D, E, K, A, C and Magnesium (helps with D intake
| issues).
| SketchySeaBeast wrote:
| I'd love some articles that back this up - I've seen low
| Vitamin D be mentioned as a comorbidity, but I don't think
| generic advice on vitamins and taking aspirin is that useful
| without any sort of evidence.
| VBprogrammer wrote:
| While on the whole you are completely correct, it's worth
| remembering that the risks associated with taking recommend
| doses of vitamins are negligible.
|
| The only plausible confounding factor is people behaving
| less responsibility in the belief that they are somehow
| safe. On a personal level, try not to do that.
| coding123 wrote:
| This is great advice. If you have a chance to get the
| vaccine, that's the best option. But keep wearing masks,
| and try to not get the virus in any ways you can.
| Vitamins are basically boosting your immune system, and
| as a bonus there are studies that back up that it
| actually helps in some cases 77% better outcomes
| (potentially more). That doesn't mean you can't die from
| covid even if you're taking these vitamins (as well as
| with the vaccine).
| SketchySeaBeast wrote:
| Yeah, vitamins I understand, but Aspirin has negative
| effects with constant long term use. I'm just not
| comfortable with those recommendations without any effort
| to support.
| coding123 wrote:
| Vitamin D
|
| https://www.sciencedirect.com/science/article/pii/S09600760
| 2...
|
| https://pmj.bmj.com/content/early/2020/11/12/postgradmedj-2
| 0...
|
| Statins
|
| https://health.ucsd.edu/news/releases/Pages/2020-09-23-stat
| i...
|
| Vitamin A
|
| https://chrismasterjohnphd.com/covid-19/iga-antibodies-
| vitam...
|
| More data is probably needed for A.
|
| Aspirin
|
| https://journals.lww.com/anesthesia-
| analgesia/Abstract/9000/...
|
| Definitely need more data on the aspirin.
|
| Vitamin D is pretty well backed up at this point.
|
| https://vitamindforall.org/letter.html
| stolenmerch wrote:
| https://vitamin-d-covid.shotwell.ca/
| pp-ir wrote:
| As far as I understood doctors, in march there was no
| guidelines for the disease. It was considered as a respiratory
| disease.
|
| Later on, it was requalified as a vascular disease, scientists
| looked at cytokines / interleukin (I AM A ELECTRONIC ENGINEER,
| please correct me doctors).
|
| Now, there is some systematic treatments earlier
| (https://jamanetwork.com/journals/jama/fullarticle/2770275), so
| yes, far fewer patients needs an invasive ventilator.
|
| And that is great.
| djsumdog wrote:
| The ventilators were a death sentence. Many of the people who
| died early on, died not due to COVID, but due to their lungs
| getting damaged by high pressure vents. Some were kept on high
| pressure for much longer than is normal.
|
| There was a lot of bad advice coming from doctors in Europe,
| and also there was the idea if you had them on a vent, they
| were on a closed air system and couldn't spread COVID in the
| hospital. This was disastrous.
|
| Doctors do not use them unless necessary today, but it's no
| doubt this is why many of the early death counts, especially
| among younger people, was so high in places with high vent use.
| adolph wrote:
| _Conclusions: The incidence of [ventilator-associated lower
| respiratory tract infections (VA-LRTI)] is significantly
| higher in patients with SARS-CoV-2 infection, as compared to
| patients with influenza pneumonia, or no viral infection
| after statistical adjustment, but residual confounding may
| still play a role in the effect estimates._
|
| https://pubmed.ncbi.nlm.nih.gov/33388794/
|
| https://pubmed.ncbi.nlm.nih.gov/?term=ventilator+covid19&fil.
| ..
| hkt wrote:
| Can you cite anything on this? I've heard it claimed before
| but haven't seen a primary source.
| corin_ wrote:
| Could you please share any sources? I know they're not used
| as much now but haven't seen any evidence that they are
| specifically to blame for deaths.
|
| The majority conclusion I've seen in Europe about why earlier
| death rates were so high in some places was that the
| hospitals were overloaded and therefore didn't have enough
| capacity (staff, equipment, etc) and therefore some died due
| to there not being enough ventilators.
|
| This isn't my field of expertise so I'm very open to finding
| out that my impression is wrong, but my gut feeling is that
| your comment is not accurate.
| war1025 wrote:
| I don't have any sources at hand, but the explanation I
| heard is that ventilators are generally used for people who
| have healthy lung tissue but are unable to breathe
| properly.
|
| Coronavirus weakens the lung tissue, but the ability to
| breathe (inhale / exhale) is unaffected.
|
| Basically the body was forcing people to have shallow
| breath to preserve the damaged lung tissue and allow it to
| recover. The ventilator essentially restored their
| breathing back to full force, which turned people's lungs
| into soup basically.
|
| Makes sense as an explanation to me, but like I said, I
| don't have any official sources for that.
| saberdancer wrote:
| People are not put on ventilators for no reason. They are
| put because their oxygen level is so level that they will
| die if it deteriorates. People ended up on ventilators
| after they received maximum possible level of
| supplementary oxygen.
|
| This explanation sounds very implausible and simplistic.
| When a person has extremely low oxygen level and you are
| giving them maximum oxygen possible, what can you do?
| Ventilator or ECMO (which is probably even more
| dangerous).
| war1025 wrote:
| This [1] seems to be a fairly representative article of
| the sort of thing I've seen. Not peer reviewed, but it
| hardly seems like fringe lunacy.
|
| [1] https://elemental.medium.com/how-one-covid-19-doctor-
| became-...
| tptacek wrote:
| Can you provide a source that wasn't written by a (checks
| notes) magician?
| war1025 wrote:
| I don't particularly care about the topic, so no.
| jschwartzi wrote:
| GM contracted with one or more actual medical device companies
| to produce ventilators under the DPA. So yes we needed
| ventilators, but we produced a ton of them to fulfill that
| need.
| sokoloff wrote:
| To be even-handed, both Ford and GM produced ventilators.
| [deleted]
| pp-ir wrote:
| => HN effect, the server is sloooow. Sorry.
|
| Pierre, the author of this article.
| mtmail wrote:
| Homepage in French https://makair.life/
|
| Translation
| https://translate.google.com/translate?sl=fr&tl=en&u=https:/...
| franky47 wrote:
| Note: the project was started during the first lockdown by the
| staff of Clever Cloud [1], a French PaaS based in Nantes.
|
| [1] https://clever-cloud.com
| koolk3ychain wrote:
| This is interesting, however, if I had covid and knew I was going
| to soon be on a ventilator. I'd much rather overdose on morphine
| or kill myself than rely on a raspberry pi based ventilator.
| selfhoster11 wrote:
| If there was nothing else available, I'd surely pick a chance
| of survival while connected to a Pi-based ventilator than zero
| chance of survival.
| exyi wrote:
| You'd be fine, most patients on ventilators are AFAIK heavily
| sedated anyway. So don't overdose yourself, please
| koolk3ychain wrote:
| When hospitals reach critical levels of occupancy or patients
| that are "near death" the option of a terminal morphine drip
| is more common than you'd think. However, I feel it's
| important to mention that anyone who wants decent medical
| care while alive should never arrange a DNR. There's actually
| clinical evidence to suggest that a DNR can actually markedly
| lower your level of care in a hospital or ICU [0]
|
| 0 - https://pubmed.ncbi.nlm.nih.gov/10448716/
| Aissen wrote:
| Yeah, the title is misguided, it is not the whole story :
| https://news.ycombinator.com/item?id=25671318
|
| (And as much as I hate the Pi's reliability, I'd still take
| that bet if it was indeed relying on a Pi).
| baptistejamin wrote:
| Hello! I work on this project.
|
| Don't worry, the breathing system does not rely on the Rasberry
| at all.
|
| We use an electronic board that was made on purpose by a
| Medical company and relies on STM32 hardware.
|
| This board sends telemetry to the Rasberry PI and we have a
| Rust based interface that shows charts and some controls.
|
| If the Raspberry fails, the Firmware still run fine, and you
| can still change the settings on the machine using physical
| buttons and a LCD screen that is directly connected to the
| firmware
| koolk3ychain wrote:
| A good friend of mine had the experience of nearly dying
| after a mobile ventilator in an ambulance failed after he was
| involved in a serious car accident. It was later found that
| the ambulance operator was using devices that hadn't been
| cleared by the FDA yet. Although they came from a Turkish
| "medical device" company, they were not cleared for use in
| the US and left my friend with brain damage and PTSD.
|
| I don't care that the hardware involved in your project was
| "made be a medical company", it's not hardened tech. Also,
| rust is by no means hardened - look into "provably complete"
| languages if you want to see what a true "hardened" lang is.
| There's a reason why medical devices and serious "hardened"
| tech (military or otherwise) is validated and cost tens if
| not hundreds of thousands of dollars. It's because teams of
| engineers spent weeks or years coming up with every possible
| problem or failure pattern.
|
| To be frank, I'd rather pay a nurse $50k in cash to pump a
| vent bag next to me than rely on your "project".
| mbreese wrote:
| While I don't disagree with your overall sentiment (I can't
| imagine relying on a RPi powered device -- even if it is
| just a display -- for clinical use), I think you're
| overthinking the motivation here...
|
| _> To be frank, I 'd rather pay a nurse $50k in cash to
| pump a vent bag next to me than rely on your "project"._
|
| From what I've read (admittedly not much) -- this project
| isn't trying to disrupt the ventilator industry or make a
| bunch of sales. It isn't designed to give you a choice of a
| ventilator to remove a nurse. It's for situations when you
| don't have another choice... for when a hospital has run
| out of proper ventilators or there isn't a nurse available.
| This is not a first-choice device (even if it could be
| adapted to that in the future).
| pp-ir wrote:
| Sorry for your friend.
|
| Problem with vent bag is that you cannot maintain a
| positive expiratory pressure (around 10mmHg of pressure
| during the expiration to prevent lung to collapse alveoli).
| For Covid-19, all the projects based on mechanized vent bag
| where useless because of the type of disease.
|
| There are several companies behind the project. The company
| who makes the electronics is Tronico (https://www.tronico-
| alcen.com/en/markets/medical). It has all the medical
| certifications needed.
|
| We are currently going on with ANSM certification
| (equivalent of US FDA). It is a long 2 years way, with lots
| of papers and tests... If it is approved, sure it can save
| life everywhere in the world. If it is not, it was a
| project where we learned a lot.
|
| By the way, ambulance ventilators are harder to develop and
| to approve. Hardware must resist huge shocks and
| accelerations.
|
| As said previously, the Rpi part and the software is not
| critical at all, it is here to fill a gap between the
| minimal UX and the expected UX. See
| https://news.ycombinator.com/item?id=25671617 and
| https://news.ycombinator.com/item?id=25671318.
| jeroenhd wrote:
| I agree that this project can be incredibly dangerous if
| people try to sell them in countries with well-developed,
| well-tested systems of healthcare.
|
| However, billions of people don't have the luxury of tested
| and verified medical devices. The price of a single machine
| might be close to the monthly budget of the entire
| hospital. In those cases, any small hacks are welcome if
| they can help save a patient's life. A crappy, half-decent
| ventilator is way better than no ventilator at all. Until
| rich countries start buying hospital devices for poor
| countries en masse, providing cheap alternatives to proper
| medical devices can save lives.
|
| The company behind this seems to be French and if it ever
| gets used in France without certification then they've
| probably got a huge lawsuit and potential criminal
| liability on their hands.
|
| According to the project's website, they are trying to
| comply with European medical regulation (if Google
| translate got that right) and their Github mentions they're
| working with regulators. This isn't a hobby project by a
| bunch of bored students, the project seems to be a proper
| attempt at making capable medical devices that can be
| extended upon without IP problems.
| kbelder wrote:
| To be frank, more people would be saved with fallible yet
| cheap medical hardware than 'proven correct' hardware that
| costs $100,000 plus.
| bird_monster wrote:
| That's fair for you individually. For a lot of people, "I'd
| rather try to live than die" is a much more realistic
| viewpoint.
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(page generated 2021-01-07 23:02 UTC)