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The naiveté being expressed in the comments here and as the premise behind the ventilator is astounding. I though I would share some information to put things in perspective:

- If you are unwell enough to need a ventilator then the ventilator itself is going to the least of your worries. You will need the drugs and expertise to care for you. The current respiratory illnesses going around aren’t like polio and the iron lungs where all you need is help breathing.

- If you can sort the above to have any hope of survival you need a “modern” ventilator that can operate in way that this simple homebrew device is physically not capable of offering. Most of the improvement in caring for people with ARDS is based upon careful and tight control of ventilatory parameters to prevent secondary lung injury.

- Modern ventilators have a price tag of if you have to ask you can’t afford it.

So in summary this is a nice build but serves no practical purpose.




This is correct.

Particularly the “if you are unwell enough to need the vent, the vent is the least of Your worries.”

The vent keeps you oxygenating while we address the (usually multiple, overlapping and interacting) severe issues that led to you needing the vent. This is ICU-level care. A vent without an ICU doc and appropriate medications (and ideally a resp tech and a nurse) might as well be an origami crane.

Hospitals will run out of one those other things, on average, before they run out of vents.


In Wuhan they ran out of hospital capacity and sent people home. People bought vents to administer to their relatives at home without medical supervision.

You need to dispose yourself of the false assumption that people who need vets would even be able to get through the door at an ICU during a serious pandemic.


I hope those folks, well-intentioned as they may have been, did not deprive actual hospitals from getting the equipment that they needed by doing this.


Could you please provide the reference? The ventilation procedure is very difficult and dangerous to carry out, and I've seen people confusing oxygen mask and related devices (as treatment for mild syndromes) with ventilators.


considering the cost of ventilators I doubt that people in Wuhan were using them in any numbers likely to be noted, thus yes, oxygen masks and related devices most probably.


I expected the answer that amateur solutions won't work from medical professionals and expected that to be correct.

But obviously, the question many people are concerned with now is "can't we triangulate?" When you have an epidemic threatened to overwhelm medical facilities and we know the physical construction of some these devices isn't by itself that complex, isn't there a way a more organized and knowledgeable DIY approach could work when the naive, uninformed approach certainly wouldn't?


On the subject:

"WHO urges stocking up on ventilators to combat coronavirus"

https://www.channelnewsasia.com/news/world/who-urges-stockin...


Thanks for chiming in.

If I understand what you're saying correctly, you're saying that in the case where one would be so sick as to require a ventilator, they'd be in a situation where the ventilator only buys more time before the condition worsens, but doesn't actually address the root cause of the problem. As such, even if someone were to find a hospital-grade ventilator that fell off the back of a truck and managed to properly use it, the non-ventilator care is what makes the difference in outcome, not the ventilator itself.

Is that correct?


Not quite. The vent process itself requires careful management to provide net benefit (eg, controlling the level of sedation, avoiding secondary lung injury).

So while the non-vent care is what makes the difference, improper use of a hospital grade vent is more likely to do harm than good. Eg, Vents frequently clog. It requires a little bit of clinical experience to recognize that as what’s happening, and intervene appropriately. It’s not a complicated thing, and anyone that’s worked the ICU for a bit can recognize and handle it, but it would be a killer in the hands of a layman, and it’s only one out of a hundred issues.

Additionally, I’d hesitate to describe it as buying time, because that implies a linear sequence. Let’s say you have condition X that implies oxygenation and blood perfusion. Vent manages oxygenation while I work on maintaining perfusion and the underlying X, but if all I have is the vent, the patient will still die from lack of perfusion. The vent didn’t buy any additional time, it just closed off one route of death temporarily.

When a patient needs a vent, it’s very rare that the vent is the only route to death that is being proceeded along.

This was pretty stream of consciousness, but I’m typing in the bathroom, so ... sorry if it’s a bit of a mess.


How do you maintain perfusion?


It depends on the precise mechanism of failure, but generally a combination of fluids of various concentrations and extravasation characteristics, and drugs that either cause the constriction of blood vessels, or increased heart pumping strength, or both (these often pop up in popular media as “pressors”).


> a hospital-grade ventilator that fell off the back of a truck and managed to properly use it

Step 1 is inserting an ET tube in the patients mouth and down past the vocal cords without killing them in the process. So hope your truck also drops a laryngoscope.

Step 2 is picking the 6-7 parameters on the vent so you don't burst the lungs like an overfilled balloon or suffocate the patient because their throat is now sealed and you aren't providing enough O2. So steal a doctor from the truck too.


Theres all that and then the fact that the ventilator itself can make you sick. The number of patients (among hundreds) I have known on long term ventilator support that didn’t have a case of pneumonia in five years I can count on one finger.

Not to mention ventilators will damage your lungs if not correctly configured.


Can you elaborate on what else is done to treat those patients? I was under the assumption that the pandemic situation is caused by a virus and that not much can be done against a virus besides waiting for the body to heal itself. (Which is not entirely true, since AIDS can be treated nowadays.)


You’re correct there’s not a lot to be done for the virus itself - in that situation, care tends to become about protecting the various organs suffering in the process, to get the patient through it.

For example: a patient presents with acute respiratory distress and sepsis due to the flu, covid, whatever. The fluid in the lungs will be creating a burden on the heart; the general inflammation will be pissing off everything, including making blood vessels both leaky and dilated.

The burdened heart is now prone to being overtaxed. With leaky vessels, it’s also prone to being under supplied. And oxygen isn’t coming across the lungs well. A mismatch between its blood/oxygen supply and demands causes what’s called a demand ischemia - you can think of it as a kind of heart attack. This further weakens the heart.

This shortage of both supplied blood, and oxygen in the blood, plus systemic inflammation, can hit every other organ: kidney, liver, gut, etc.

This is where you can start to see some shock liver kick in. Which means one of our core mechanisms for metabolizing drugs (and everything else) is telling us to fuck off.

The same shock effect can hit kidneys. Reduced perfusion not only hurts kidneys, but means waste dumping into urine is being decreased, or not happening. We try to prop up kidney function. We also add fluids to try and increase perfusion (but if we have had an ischemia, the same bulk of fluid that is needed to maintain perfusion pressure can also act as a burden on a weakened heart.)

If the gut goes significantly ischemic, it can die. Even if it doesn’t die, local inflammation and reduced food intake can make it leaky. You’re not necessarily seeding bacteria into the blood that way (studies of pancreatitis w associated sepsis suggest that’s not a major contributor), but the gut associated lymphoid tissue is definitely going to be kicking into high gear and promoting our inflammation storm even more.

So, we try to carefully maintain perfusion, which involves monitoring and calibrating our support for heart, kidney, lung, etc. in an ongoing and dynamic fashion. And not uncommonly, besting down infections that develop along the way, because a bunch of plastic in the body is a badness.

I don’t work much in the ICU, so if I’ve misrepresented something and we have an intensivist on hand, I defer to them.


Thanks a lot. That's a great explanation.


While a bad ventilator in the wrong situation may be worse than no ventilator, sometimes no ventilator means you are dead.

It is highly unlikely that anyone will build this and attempt to treat a patient at home without reading anything.

> Modern ventilators have a price tag of if you have to ask you can’t afford it.

That seems like an excellent reason for more people to look in to and think about how to reduce cost of a useful ventilator for emergency use, as an essential (but not sufficient) part of supporting large numbers of concurrent patients suffering ARDS.

Yes, if you are hypoxemic, your brain's going to be telling you to hyperventilate, which means they'll have to administer drugs to prevent you from fighting the vent. Yes, at present, there is no automated system that would be able to support a patient in any meaningful way.

However, it is worth thinking about.


> It is highly unlikely that anyone will build this and attempt to treat a patient at home without reading anything.

I’m not going to pretend that 0% of the human population could manage a ventilated patient with nothing but the appropriate texts, but it’s pretty damn close to 0%. Hell, a fresh third year med student would almost certainly kill a patient in that situation, and they’re at least supposed to understand the relevant physiology and drugs.

The vent is a tool for adjusting a couple of physiologic parameters, in the context of what is usually severe and complicated disease. It doesn’t manage anything by itself, and it’s not a RTFM situation.


It is not hypoxemia that is detected, the regulation of breathing depends on the level of carbon dioxide in the blood instead.


There is also a hypoxic breathing drive but it is weaker than the hypercapnic drive.


>It is highly unlikely that anyone will build this and attempt to treat a patient at home without reading anything

unless if they had read some stuff about what was required in treatment they decided making a ventilator was worthless, which is basically what people knowledgeable about treating patients are suggesting.


It is highly unlikely that anyone will build this and attempt to treat a patient at home without reading anything.

Citation needed.


> - Modern ventilators have a price tag of if you have to ask you can’t afford it.

Not sure about the efficacy, but I was reminded of this discussion ("A doctor in Bangladesh has found a simple way to treat infant pneumonia"): https://news.ycombinator.com/item?id=17945071


You the nail right on the head. Especially regarding VALI. Personally, I’d also be worried about any residues in the system (e.g. lubricants, grease, etc.) being blown into your lungs. That’d be an excellent recipe for a hellish aspiration pneumonia on top of the underlying illness.


Not asking about DIY, but since you are more knowledgeable about medicine than I, you might know. Dialysis exists. Could a variant of a dialysis machine oxygenate blood and scrub it of carbon dioxide to treat an ARDS patient? Is the main problem that dialysis can't move a high enough volume of blood to keep a person alive?


Isn't that basically what ECMO is? like a super intense way to do all the things we need to live via our blood outside the body


Yes, it's also what a "heart lung machine" is. They even use oxygenators that are very similar in construction to dialyzers used in dialysis.



Well, TBH we don't really know how to ventilate ARDS. Doing so will likely require new paradigms in ventilatory tech.

So yeah, useless but fun!




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