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Risky hack could double access to ventilators

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Re: Risky hack could double access to ventilators

#71

Post by btilly »

Findeton wrote: post #32
speedgoose wrote: post #24

Earlier quoted context omitted.

People stop very fast when people they know start to get sick and die.

When that happens, it's too late. Between the incubation period and the time to death it's about three weeks. At a 20% increase per day that means that even if you stop going out at that moment deaths will be multiplied by 46. If the rate is 30%, the multiplier is 247.

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 rooms. By the time people's behavior modifies through direct experience, it is too late.

Making this concrete I live in Orange County, CA. Population, 3.3 million. Hospital beds, 6600 (source https://www.hasc.org/orange-county). I don't know how many ICU beds, but https://www.accjournal.org/journal/view.php?number=630 suggests it likely is about 6% of the total. So about 400ish.

Now walk that backwards. 400 people in ICU beds probably means 4000 people with symptoms means less than 0.1% of the population with COVID. Except that it is worse than that. We have those beds for normal stuff that goes wrong. They aren't actually empty now.

Long story short, we start piling up excess dead bodies due to lack of capacity long before most of us personally know anyone who actually shows symptoms.

Re: Risky hack could double access to ventilators

#72

Post by JshWright »

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.

Interesting, I'd be curious to know more. My understanding of NPV is that it's primarily useful in cases when the lungs are generally "functional" and some other issue is preventing adequate ventilation.

Re: Risky hack could double access to ventilators

#73

Post by koheripbal »

mrob wrote: post #65

Is negative pressure ventilation any use in treating Covid-19? Iron lungs are easier to build than positive pressure ventilators. I imagine many HN readers could build something like a Both respirator[0] in their garage over a weekend. Using negative pressure ventilation might be a better option than trying to attach multiple patients to a positive pressure ventilator. [0] https://en.wikipedia.org/wiki/Both_respirato…

Is that what these are?

https://www.youtube.com/watch?v=SVodALR3Zoo

Re: Risky hack could double access to ventilators

#74

Post by mkl »

atdrummond wrote: post #67

There are some odd quotes and grammatical mistakes in this article. For example: “You wouldn’t want to put a patient with severe bronchospasm [sudden contractions of bronchial muscles in the lungs] with a patient that does not have bronchospasm because that would.” Likewise, one of the cited authors’ names, Babcock, is misspelled in the piece as Babcok. I’m not qualified to assess whether this risk is worth it but I…

> one of the cited authors’ names, Babcock, is misspelled in the piece as Babcok.

And also "Babock".

Re: Risky hack could double access to ventilators

#75

Post by Wowfunhappy »

atdrummond wrote: post #67

There are some odd quotes and grammatical mistakes in this article. For example: “You wouldn’t want to put a patient with severe bronchospasm [sudden contractions of bronchial muscles in the lungs] with a patient that does not have bronchospasm because that would.” Likewise, one of the cited authors’ names, Babcock, is misspelled in the piece as Babcok. I’m not qualified to assess whether this risk is worth it but I…

Vice’s articles are always full of typos. I suspect they don’t have a copy editor.

It’s unfortunate, because their reporting seems to be quite good.

Re: Risky hack could double access to ventilators

#76

Post by Mvandenbergh »

Interesting. This has been done before (after LV shooting) but has conventionally been considered as an intervention suitable for treating mass trauma. That's because people who are otherwise in good health are easier to ventilate than people with stiff, non-compliant lungs caused by inflammatory viral ARDS.

Ventilating people with ARDS is hard. You have to use low, carefully considered tidal volumes and essentially allow the patient to be hypercapnic (CO2 higher than ideal), sometimes quite severely. You're doing a delicate dance between ventilating in a way the lungs can take and maintaining blood gases compatible with life.

Re: Risky hack could double access to ventilators

#78

Post by Zenbit_UX »

Continuous wrote: post #48

This is ridiculous! Hacks are ok with web and app deployments where you are able to patch and fix to your heart's content and the damage is not life threatening. I have worked with the medical industry, the amount of formal validation and verification that goes through on software is insane compared to what we have in the "move fast and break things" world. Even if it is "temporary" and "desperate" I would stay away…

Such a foolish statement, you clearly don't understand the number of lives lost due to ventilator shortages right now or you'd delete your comment in embarrassment. Doctors should be using absolutely any method available to them to maximize lives saved. You don't need to "have worked with the medical industry" to understand this perspective.

Re: Risky hack could double access to ventilators

#80

Post by Mvandenbergh »

pbhjpbhj wrote: post #43

Have governments made orders (legal or purchase) for manufacture of ventilators by large scale companies? Presumably ventilators are a relatively niche product - what's in them that the World's industrial complexes can't ramp up production of within a couple of weeks? I imagine it's the pumps that's the limiting factor? Given humanity already has the working tested, established designs. Can't governments requisition…

So there are four main ways for breathing machines to be powered: 1) By compressed air from a wall port (majority of ICU machines)

2) With bellows (anesthesia machines)

3) Turbine, either dynamic or constant speed with a proportional valve (home use or patient transport)

4) Piston

Let's assume that we use a pneumatic device driven by centrally purified air as that is simplest. The parts then are:

-Gas blending to mix O2 and HP air

-A fast, precise, and accurate proportional solenoid valve. This turns the constant pressure into the desired waveform

-another valve for controlling exhalation pressure. Can be another proportional solenoid, alternatively a manually adjustable valve to ensure constant minimum end exhalation pressure (PEEP)

-Flow sensor (range of options, typically variable orifice or hot wire anemometer but other type exist)

-Pressure sensor (silicon waver transducer)

-Overpressure valve

-O2 sensor (highly desirable, arguably you can estimate from O2 blending settings but that will work better on a very well characterised design which this would not be. Anyway O2 sensors are widely used so this will never be a constraint.

-Piping to connect it all together

-A control and alarm system to drive desired waveform based on user settings and sensors

-Patient circuit: Humidifier / heat exchanger, patient valve (one time use), viral filters for intake and exhalation air (one time use), ET tubes (one time use)

Probably the limiting factor as far as parts go are the valves since this is a niche application.

Here's the problem: as a civilisation, if we had to make a hundred million vents by the end of the year it would be easy. Expensive, sure, but not that hard in an emergency.

It is much harder to make an extra 50,000 in a few weeks because it just takes time to turn the machinery of mass production in a different direction.

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