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Risky hack could double access to ventilators

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Re: Risky hack could double access to ventilators

#141

Post by nerdponx »

sp332 wrote: post #105
btilly wrote: post #71

Earlier quoted context omitted.

Not quite that bad. Current measured growth rates are closer to 15% per day (5 day doubling time). And people's behavior changes not when people die, but when people get sick. Which happens (depending on your sensitivity) only 1-2 weeks after exposure. But the basic principle still applies. We are trying to buy as much time as we can to ramp up emergency provisions. And are trying to avoid overwhelming emergency room…

The growth rate is different in different countries. The USA is currently on a 35% slope. http://nrg.cs.ucl.ac.uk/mjh/covid19/

New York's growth rate is going to look terrifyingly high as testing capability ramps up significantly.

Re: Risky hack could double access to ventilators

#142

Post by forkexec »

theturingnerd wrote: post #19
bitexploder wrote: post #3

This is really neat. It seems a lot of the risk is how specific lung capacities and conditions interact with the ventilator and how much oxygen someone needs. My question to any MDs reading this: how often do you have to tweak ventilator volume for patients using one? What is the feedback loop? Blood oxygen levels?

(physician here) Vents can be quite tricky to get right; primarily because as disease progression continues on many things change. We are always trying to balance the deleterious effects of the intervention (in this case, the vent) with the goals of care. What most people don't know is that vents cause a lot of injuries on their own. (See ARDS). Hypoxemic respiratory failure is serious stuff, and it's almost always n…

IANAMDOMP. After respiratory therapists, it seems like perfusionists will be stretched thin too because there are so few of them globally. I would predict lots of ECMOs and long waiting lists for lung transplants in the next few months, but also lots of poor outcomes for COVID patients with preexisting cardiopulmonary issues. I just hope young and middle-aged people take it seriously and don't avoidably waste healthcare resources through irresponsible behavior.

Re: Risky hack could double access to ventilators

#144

Post by AstralStorm »

fifteenforty wrote: post #70
JshWright wrote: post #69

Earlier quoted context omitted.

No, in the case of ARDS, you need positive pressure (especially "back pressure" during exhalation) in order to keep the alveoli open. https://en.m.wikipedia.org/wiki/Positive_end-expiratory_pres...

We are talking about negative pressure mechanical ventilation. Positive end expiratory pressure is just one way of splinting open alveoli. Maintaining recruitment and V/Q matching in ARDS can be achieved in multiple ways, including negative pressure mechanical ventilation.

Anyway, the ventilator hardware is relatively easy to make, a gas pump, reduction and humidifier, plus a few hoses. Literally your granddad's CPAP sleep apnea machine is (almost?) good enough, if it has tuned oxygen intake. I would wager intubating actually makes most problems worse in case of damaged lungs, but with low odds only.

The real problem will be getting actual oxygen (concentrators are not free) and people to tune the system.

Re: Risky hack could double access to ventilators

#145

Post by AstralStorm »

bootlooped wrote: post #122
notabee wrote: post #118

Earlier quoted context omitted.

All of those break down the mask fibers or screw up the electrostatic qualities used to grab particles. There have been studies on it, but there's not really an ideal way that doesn't damage the filtering capacity over time.

From what I understand the virus breaks down with time at room temperature anyway, so you could possibly just get away with tossing them in a box for 10 days (or whatever time gets you 99+% virus breakdown). That would have minimal negative effect on the filter material and elastic straps.

Alternatively you could bake some masks, high enough temperature will kill the virus. Or sanitize it with chlorine gas.

Re: Risky hack could double access to ventilators

#146

Post by AstralStorm »

tyingq wrote: post #77

Makes me wonder if there's now a black market and/or hoarding for CPAP and BiPAP machines. Not really a substitute for a ventilator, but better than nothing if the hospital has nothing for you.

You do need oxygen though, moistened and well tuned percentage to pressure.

Would require a modification to the mask or hose for most of these machines. (One way valve from O2 source at least.)

Re: Risky hack could double access to ventilators

#147

Post by lee »

theturingnerd wrote: post #19
bitexploder wrote: post #3

This is really neat. It seems a lot of the risk is how specific lung capacities and conditions interact with the ventilator and how much oxygen someone needs. My question to any MDs reading this: how often do you have to tweak ventilator volume for patients using one? What is the feedback loop? Blood oxygen levels?

(physician here) Vents can be quite tricky to get right; primarily because as disease progression continues on many things change. We are always trying to balance the deleterious effects of the intervention (in this case, the vent) with the goals of care. What most people don't know is that vents cause a lot of injuries on their own. (See ARDS). Hypoxemic respiratory failure is serious stuff, and it's almost always n…

I've got a really naive/dumb question for you.

Could you use a CPAP machine as a poor man's ventilator? Would it be better than nothing?

There's definitely a ton of CPAP machines out there.

Re: Risky hack could double access to ventilators

#148

Post by etrevino »

lee wrote: post #147
theturingnerd wrote: post #19

Earlier quoted context omitted.

(physician here) Vents can be quite tricky to get right; primarily because as disease progression continues on many things change. We are always trying to balance the deleterious effects of the intervention (in this case, the vent) with the goals of care. What most people don't know is that vents cause a lot of injuries on their own. (See ARDS). Hypoxemic respiratory failure is serious stuff, and it's almost always n…

I've got a really naive/dumb question for you. Could you use a CPAP machine as a poor man's ventilator? Would it be better than nothing? There's definitely a ton of CPAP machines out there.

A doctor asked me that-- a fact I found disturbing, because shouldn't he know-- so I did some research. And I found out that the machine would spread the virus everywhere with the outgassing (I'm not sure if that's the right term).

Re: Risky hack could double access to ventilators

#149

Post by ummonk »

nerdponx wrote: post #141
sp332 wrote: post #105

Earlier quoted context omitted.

The growth rate is different in different countries. The USA is currently on a 35% slope. http://nrg.cs.ucl.ac.uk/mjh/covid19/

New York's growth rate is going to look terrifyingly high as testing capability ramps up significantly.

It is ramping up significantly, with a corresponding growth rate of confirmed cases. 4 days ago it was approaching 1000. It will probably be 10,000 by tomorrow.

Re: Risky hack could double access to ventilators

#150

Post by fifteenforty »

markmichalski wrote: post #90
fifteenforty wrote: post #37

There are lots of problems with this, but I think it is possibly a better move than some of the home-built ventilators you see floating around. I’m biased though: I’ve designed a 3D printed improvement on this idea that potentially allows you to ventilate multiple patients with different pressures: https://www.prusaprinters.org/prints/25808-3d-printed-circui...

Fellow MD trying to help with engineered solutions. Perhaps check this out as well; someone used a common valve from a hardware store to titrate pressures up and down: https://www.youtube.com/watch?v=eSVbwWANqRI&feature=youtu.be . I've been thinking about how we might increase ventilation to one part of the circuit if the pCO2 drops too badly--any thoughts there?

Thank you for pointing this out! I’m trying work out how to get in touch with this guy, unfortunately he has turned off all comments.

I’m not sure I understand your question: do you mean if the one patient is getting hyperventilated? My suggestion is to set the pressure settings to ventilate the poorly compliant compliant lung, then use the flow restrictor to compensate on the more compliant lung.

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