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Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 3:29 am

I am new poster on this forum but I read the foums a lot. I know the capabilities of the raspberry pi and how versatile it is. My son and I use it to projects in our home. I was brainstorming tonight and I just wanted to get some input from all of you. The news talks about the big demand for respirators needed with the outbreak. Why could we not use a small dc minidiaphragm air pump use the RPI to control the pump add lets say an mcp3008 digital converter to attach a pressure transmitter to it. I looked up in a medical journal that inspiration and expiration pressure is around -4 mmHg. We put a small display or control the unit using bluetooth. Pressure could be controlled and using a cheap relief valve like a teflon or foil seal or a flap that would pop in an overpressure situation. I know this would not be an easy project because its a medical application. But I thought what a great tool the Raspberry is and how we might be able to use it.

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davidcoton
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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 10:16 am

I know nothing about respirators, so can't comment on that.
I think the problem would be getting the Pi (and the surrounding system) qualified for a life-critical medical application. It would need an extraordinary effort, probably with significant input from medical equipment specialists.
I would be surprised if it would be any cheaper/better/quicker than ramping up production of existing designs, but that is just semi-informed guesswork.
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wh7qq
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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 6:53 pm

Modern ventilators are the result of decades of experience and extensive testing and a lot of biomedical engineering expertise. They provide the practitioners with extensive versatility in tailoring the action to the patient's needs and condition. Volume, pressure, flow rate, gas percentage and other factors are all variables that must be accounted for in each instance and is not even consistent over a patient's course.

Cobbling together some mix of generic parts to make something that moves air is not only dangerous but almost sure to trip up on the FDA's extensive requirements that burden the manufacturer with proving safety, efficacy and at least equivalency, if not superiority to existing designs.

The lungs are an extremely delicate organ that is already compromised severely in the case of pneumonia. The potential for harm is as great from the misused or misdesigned ventilator as it is from the disease.

By the way, the proper term is "ventilator" as respiration is a complex physiologic process that goes well beyond simply moving an air mixture in and out of the lungs.

The RPi user is much better advised to stick to challenges that have little potential for damage to the human body.

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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 6:59 pm

wh7qq wrote:
Mon Mar 23, 2020 6:53 pm
Modern ventilators are the result of decades of experience and extensive testing and a lot of biomedical engineering expertise. They provide the practitioners with extensive versatility in tailoring the action to the patient's needs and condition. Volume, pressure, flow rate, gas percentage and other factors are all variables that must be accounted for in each instance and is not even consistent over a patient's course.
You'd better tell the Italians that.
https://techxplore.com/news/2020-03-d-p ... ctims.html
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thagrol
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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 7:39 pm

wh7qq wrote:
Mon Mar 23, 2020 6:53 pm
burden the manufacturer with proving safety, efficacy and at least equivalency, if not superiority to existing designs.
That's a poor choice of wording. "burden" appears to imply you'd prefer an unregulated industry.

@OP: I wouldn't go forward with this. As others have said, it's complicated and there are a lot of reglatory hoops to jump through. And no matter how many "use at own risk" disclaimers you slap on it somone is going to sue when things go wrong (they will).

Oh, it's also not enough to just connect up an air pump and a pressure sensor. You also have to make sure both your software and the underlying OS are both fault tolerant and fail safe. That applies to the hardware too.
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wh7qq
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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 11:28 pm

thagrol wrote:
Mon Mar 23, 2020 7:39 pm

That's a poor choice of wording. "burden" appears to imply you'd prefer an unregulated industry.
The implication is entirely yours...I suggested no such thing. The use of the term "burden" is to indicate that it is entirely up to the manufacturer to do the testing and make the application for approval. It is all a part of the process and it shows up in the final cost of the product just as the bits and their assembling do. It applies to every aspect of the device, from the initial concept, research and development, manufacturing and shipping to receipt by the end user and beyond. Even the print on the shipping package must be approved.

You cannot imagine all that goes into it unless you have lived it from one end to the other and it is as much a burden as every screw, pc board or line of software that goes into the end product. The burden continues with the governmental body that has been formed and continues to grow that grants the approval. They don't work for free.

The bottom line is that the process of producing a medical device is well beyond the capabilities of a freelancing hobbyist or even a group of them unless they are alumni of a medical manufacturer of competing devices. The RPi users should not waste their time and put themselves and their potential victims at risk.

This is not to suggest that an RPi could not be incorporated into the design of such a device but it may or may not be the optimal choice of microcomputers for such a design.

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Re: Brainstorming using the raspberry pi to make a generic respirator

Mon Mar 23, 2020 11:50 pm

On the topic of ventilators, I was wondering if a sleep apnea machine could be retrofitted in some way.......just a thought...

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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 12:04 am

JohnsUPS wrote:
Mon Mar 23, 2020 11:50 pm
On the topic of ventilators, I was wondering if a sleep apnea machine could be retrofitted in some way.......just a thought...
Doubtful. Those are designed to keep your airway open not to breathe for you. That said, I am not an expert on those, just a patient who's been using one for about a decade.
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thagrol
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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 12:11 am

wh7qq wrote:
Mon Mar 23, 2020 11:28 pm
thagrol wrote:
Mon Mar 23, 2020 7:39 pm

That's a poor choice of wording. "burden" appears to imply you'd prefer an unregulated industry.
The implication is entirely yours...I suggested no such thing. The use of the term "burden" is to indicate that it is entirely up to the manufacturer to do the testing and make the application for approval. It is all a part of the process and it shows up in the final cost of the product just as the bits and their assembling do. It applies to every aspect of the device, from the initial concept, research and development, manufacturing and shipping to receipt by the end user and beyond. Even the print on the shipping package must be approved.

You cannot imagine all that goes into it unless you have lived it from one end to the other and it is as much a burden as every screw, pc board or line of software that goes into the end product. The burden continues with the governmental body that has been formed and continues to grow that grants the approval. They don't work for free.

The bottom line is that the process of producing a medical device is well beyond the capabilities of a freelancing hobbyist or even a group of them unless they are alumni of a medical manufacturer of competing devices. The RPi users should not waste their time and put themselves and their potential victims at risk.

This is not to suggest that an RPi could not be incorporated into the design of such a device but it may or may not be the optimal choice of microcomputers for such a design.
Oh, I'm aware of the nature of certification. I spent a career in QA though not in medical devices.

I also agree that designing and building a ventilator, let alone getting it certified, will be beyond the majority of Pi users. And by the time you could do it it's likely the immediate need would be over.

I think we only disagree on terminology. You see it as a burder (for many the term burder will have negative connotations), I see it as a necessary cost of doing business and a process designed to protect the end user.
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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 11:33 am

An alternative to replicating modern technology is to look to the past to see if there are things which may not be as good but can be more easily built and less dangerous to use.

In that respect an "iron lung" should be a lot easier to construct than a modern ventilator.

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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 11:48 am

Thinking outside the box is better than burying your head in the sand...

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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 12:53 pm

I’ve noticed lately when I see the word “respirator” in an article it is often referring to those N95 masks. Not any mechanical breathing device.

Seems like odd word usage but so do a lot of medical terms.

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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 2:51 pm

I'm sorry but I wouldn't trust that to treat my Sleep Apnoea let alone keep me alive in an ICU.

There's no monitoring of exhalation, so no adjustment to make that easier. I'd expect this approach to be worse for COVID-19 patients with weak lungs than not using anything as they'll have to fight the machine when exhaling.

I wouldn't tust a $20 Chinese CPAP machine either.
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Re: Brainstorming using the raspberry pi to make a generic respirator

Tue Mar 24, 2020 6:27 pm

echmain wrote:
Tue Mar 24, 2020 12:53 pm
I’ve noticed lately when I see the word “respirator” in an article it is often referring to those N95 masks. Not any mechanical breathing device.
Correct. My daughter is in charge of procuring these for a local medical facility and currently several cases floating around here.

A 'respirator' is simply a mouth cover sometimes with one-way valve to facilitate exhale. Just one step up from dollar store paper filter. Not that effective for protecting you from inhaling virus particles but mostly helps by keeping your fingers away from your face.

https://en.wikipedia.org/wiki/Respirator
A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres, including particulate matter such as dust
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