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Ventilators 101: What they do and how they work (hackaday.com)
197 points by szczys 12 days ago | hide | past | web | favorite | 78 comments

"There’s an argument that “if there aren’t enough ventilators and patients are being turned away, I’d rather have a slim chance with a hacked solution than no chance with no solution. The reality is closer to “if there aren’t enough ventilators, a hacked solution will most likely do more damage than good, take up too much time from already strained health care resources, and could lead to death.”"

This is a difficult point for many people to understand. Sometimes the problem really is too complicated for a simple solution.

I really wish YC would do their part and start nuking all the DIY ventilators articles. I don't want to wait for homebuilt vents and intubation to start killing people before we put an end to this nonsense.

It's a great illustration of why disaster coordinators want real engineers, not software engineers.

Programmers, just get out your checkbooks and stop trying to help.

What’s a “real engineer”? Railroad Engineer? Civil Engineer? Aerospace Engineer?

Don't be cute. Professional Engineer / Chartered Engineer is a "real" engineer. A random coder calling themselves an "engineer" doesn't make them qualified to design and implement life-critical safety systems.

Some countries have that norm, but in the United States, PE licensing is fairly unusual, due to rules allowing corporations to have one PE sign off on the work of a lot of engineers. As a result, even in the case of critical medical equipment, most of the real engineers who scoped, designed, and tested the product are not PEs.

Often the PE is more of a lawyer than an engineer. They typically do have an engineering degree, but are years out from any hands-on engineering work. They do final legal sign-off, and are knowledgeable about statutes and insurance policies, but rely on people with more recent technical experience to do any technical work.

Sure, I could imagine that is the case in fields like nuclear engineering. All the PEs I know are smart and have technical chops. Though, most of my PE friends are fairly young (early 30s) and are maybe on their way to that destination.

"Some countries have that norm, but in the United States, PE licensing is fairly unusual, due to rules allowing corporations to have one PE sign off on the work of a lot of engineers."

Which is significantly stronger than the state of software engineering.

There is such a thing as Software Engineers, but most developers are not that.

In this case, I think it means someone with the perspective to think things through at a systems level and relevant domain expertise.

So, a medical device engineer.

Probably someone with a PE license.

Someone that has at least passed the fundamentals of engineering exam, preferably with a PE. Then we could guarantee a minimum understanding of the relevant fields.

Engineer who pAssed the FE exam here. 9 years design experience. I can do math.. what's needed?

I agree programmers are not on this level.

Why 'level'? Its a different body of knowledge.

Tons of programmers are on that level - in fact, probably more developers at 'Engineering caliber' than any other Eng. discipline.

That said - the vast majority of developers are nowhere near that.

It's a really long tail.

I assume Boeing engineers are enough

I've previously expressed my concerns that the focus on ventilators will lead to a secondary pandemic of antibiotic resistant secondary infections. But I don't think "nuking" these articles helps. I think it is much better for them to make the front page and get appropriately criticized. That pattern seems to be actively fostering better articles making it to the front page.

I also wonder what's so bad about all the simple existing designs, which are all out there, ready to be produced (and validated to work?)? I would understand if people would focus on taking these designs and adapting them for different materials/.... What I don't get is, that everyone is trying to reinvent the wheel (probably classic NIH-syndrome).

When all you have is a hammer, every problem looks like a nail. With an Arduino and the ability to program, we get ventilator designs. Elsewhere there are masks and gowns being hand sewn, hand fabricated, or 3d printed.

Maybe the existing designs are fine. They might also be proprietary though and controlled by slow moving corporations (as opposed to fast moving ones and startups). There may yet be good opportunities for innovation but the main thing is to spike the rate of production. Yes while being safe and legal, those are table stakes.

Anyway reinventing the wheel is underrated. Taking actual wheels as an example, there’s a long and impressive history there and we’re not close to being done yet. And so with most other things.

It’s a nightmare with the crowd that was so in love with Quinines the last few days. The argument is, basically, “I believe in science, but not during a crisis”. I guess that saying about foxholes and atheists isn’t entirely wrong.

At its core, these are all variations of Pascal’s wager. I believe what would be most useful is pointing out that using the scientific method does not automatically lead to multi-year 3-phase trial requirements. It’s perfectly possible to use the statistical methods we usually do, but adjust parameters such as cutoffs for significance or weighting of side-effects to better match our preferences and increased risk tolerance.

> The argument is, basically, “I believe in science, but not during a crisis”. I guess that saying about foxholes and atheists isn’t entirely wrong.

An important factor here is also the unfettered, obnoxious arrogance that seems to be ubiquitous in tech culture. It's not so much "I don't believe in science" so much as "I'm above science, and therefore already understand all of it."

It's the idea that if you have a sufficient mastery of software engineering then, by extension, you have a mastery of the technical aspects of literally every other field, whether it's medicine, science, psychology, law, or even art. (Or, at least can easily master it after reading a few Wikipedia articles on the topic.) And if only the experts in that unrelated field would listen to the ingenious ideas that you thought of just now, then the crisis would be averted.

But, I'm being uncharitable here. It also comes from a place of genuinely wanting to help during an unprecedented global crisis when we're all frightened, isolated, and feeling helpless.

On the one hand, you are imagining that arrogant thoughts you came up with are happening in the heads of these unnamed tech leaders. (Probably not the case. My guess is they do things from a humble bottom-up “let’s learn the fundamentals and go from there” kind of approach.)

On the other hand, sometimes they do upend industries by remaking things, usually by finding and banishing some devastatingly huge false assumption the legacy players have built everything around, and exploiting the opportunity that this opens up.

So yes, uncharitable.

It could lead to death, but if your alternative is dying from natural causes, I’d rather have the choice. I don’t see how it could do “more harm than good” on an individual level. On a mass distribution level, sure.

> Sometimes the problem really is too complicated for a simple solution.

I've been yelling this at the top of my lungs across a range of platforms. I understand the hubris created by the Dunning-Kruger effect. We all fall prey to that at some point or another in life.

That said, just because people don't know what they don't know it doesn't magically endow them with supernatural powers to be able to create solutions to problems that have decades of development, a complex history of evolution and are the result of intense development, testing and manufacturing by dedicated multidisciplinary teams over years of dedication.

You cant Superman ventilators.

Please stop.

Find other ways to contribute. If you must work on ventilators, call established companies making them and ask how you might be able to help. Ask to work for them for free if you are able to.

> If you must work on ventilators, call established companies making them and ask how you might be able to help. Ask to work for them for free if you are able to.

Anyone doing this should consider the possibility that the answer may be that there's nothing they can do on a useful timeline except write a check.

If you want to help, you gotta swallow your ego.

> For every complex problem there is an answer that is clear, simple, and wrong.

-H. L. Mencken

I agree with what you are saying, but to be fair it's the exact sentiment Elon Musk had to deal with in the early days of SpaceX. Thankfully he didn't listen.

That's not what Dunning-Kruger's thesis is.

I guess that makes your comment Dunning-Kruger about Dunning-Kruger.

From Wikipedia.

"In the field of psychology, the Dunning–Kruger effect is a cognitive bias in which people assess their cognitive ability as greater than it is. It is related to the cognitive bias of illusory superiority and comes from the inability of people to recognize their lack of ability."

Engineers who don't know they don't know what it takes to design, manufacture and test a life-critical medical piece of equipment at scale. Yup, very much Dunning-Kruger. They think they know far more than they actually do. There's was a link HN just a few days ago from a bunch of physicists who set out to design a ventilators using, among other things, Home Depot parts. Let me put it this way. We have someone in my family with a PhD in Physics. Super smart guy. He has never built anything and can't build anything, much less life saving devices by the thousands.

DK doesn't just apply to "dumb" people. I have worked with dozens of engineers who don't understand just how much they don't know.

Maybe not the strict intent of DK, but very much the same kind of effect.

Let's not split hairs. I think you know what I meant.

I've worked at companies that do light manufacturing. Light manufacturing because we contract out components to houses that specialize in that. I feel like a lot of software people don't get that hardware at scale requires 10X the amount of resources each step from design to production to shipping and support.

hardware also fails in the field in unpredictable ways. Especially to anyone without long practical experience.

Exactly. There's a general and very real disconnect with what it takes to make things. I watch the White House and Gov. Cuomo's press conferences every day. The repeated questions about test kits, beds, ventilators, etc. drive me up a wall.

I calm down when I realize none of the people asking the questions understand manufacturing one bit. And then I get rattled again because they are communicating falsehoods to the general population. We don't have enough masks, test kits or ventilators because you can't Superman hardware production.

It isn't Trump's fault or anyone else's. It takes time --lots of time-- to setup a manufacturing process and start to produce product at scale with consistent quality and performance. Weeks for the most trivial of products, years for more complex hardware. Yet people don't have an understanding of this.

Ventilators? Holy cow. Talk about not being able to Superman something into existence.

If people understood they would realize that we made a massive mistake over the last 50 years by allowing our industrial base to evaporate and migrate to China to the extent it has. Consumers are as much at fault as the decades of incompetent politicians who allowed this to happen. While we bothered with nonsense (wars, etc.) China quietly went from an agrarian society to the second economy in the world. And, even worse, the world's factory. We, quite literally, cannot make anything in the US or Europe without Chinese components and, in some cases, all we are able to do is design in the US or Europe and have no choice but to manufacture in China.

I suspect things might change over the coming years. The money we wasted in wars would have been far better spent keeping industry alive locally. Yes, subsidies, no taxes for manufacturers, relaxed regulatory burden, etc. Either we do those things or the next pandemic will, once again, find us not being able to even manufacture face masks at scale. How laughable is it that people have to sew face masks at home in the US? Sad.

BTW: In Spain they just woke up to the reality that they received 340,000 bad test kits from China.

I'm not a manufacturing expert, but if came down to it and I was sick and only had the choice between "drowning alone as my lungs filled up with mucus" and "trying a ventilator that probably doesn't work and was built by an idiot using Home Depot parts and a Raspberry Pi" I'd still go with the idiot.

Sure, ideally we'd want the certified equipment, built by the professional knighted safety engineers, stamped by the right bureaucrat, with 1000 pages of documentation proving how thoroughly expert-approved they are, but when you run out of these, what do you do?

The problem with that idea is that the application of a ventilator is far more nuanced than inflating a car tire. A home-brew ventilator could kill you faster than the mucus (and likely in a horribly painful way, for example, causing your lungs to bleed internally).

My dad died from multiple strokes this Feb. When he was transported to another hospital for a brain surgery he was intubated. A couple of days later, the ICU doctor came and told us to prepare to fulfill his wishes. They said to have him intubated again would cause a great pain for him. Also, chest compress would be lots of pain. We did let my dad go in peace. Here I am, wondering if people know what it feels like to be intubated? It is not something you can do off and on when you feel like it. There was a team of anesthesiologists there to seduce my dad when they shoved the tube in his wind pipe.

The mortality rate of ventilated COVID-19 patients could be 80% [1]. I get that we don’t want people to die, but at what point is this standard intervention just cruel? It feels like we should have a serious discussion about palliative care.

[1]: https://www.thelancet.com/journals/lanres/article/PIIS2213-2...

One of the Guardian articles mentioned in passing that, in normal times, hospitals put people on ventilators that maybe they shouldn't from an ethical perspective (I think the doctor's exact words were that he wouldn't want an 85 year old relative of his to be put on one) and that this was the first thing they'd have to give up on in a serious Covid-19 outbreak.

yea but we dont have any data as to why? is it because some number of them were over/under anesthetized? is it because of the triage criteria? I do agree that palliative care is a critical discussion because of the mortality rates for the very elderly-- some people are just to frail to ever have good outcomes from intibation.

by the way, the critically interesting thing in that piece from the lancet is that the rational for discouraging non invasive respiration is a lack of good masks and negative pressure rooms. These are problems where I think there has been an historical lack of imagination and are ripe for some novel solutions.

He was intubated because it was necessary during the transportation and the surgery. They said that they didn't want my dad stop breathing while being transported if anything happened during the trip. Plus, they said the surgery causes a lot of trauma and I think they were afraid the breathing would stop.

A few days after the surgery, he couldn't even breath on his own: MRI showed that parts of his brain were damaged. At that time, I think it's more sympathetic to let him go instead of making his life depending on a ventilating machine for the rest of his life.

A lot of end-of-life care is to prolong life enough to give the living time to say goodbye.

Hard to say goodbye to someone who is sedated...

It's easy. The hard part is being heard.

It's torturing the dying for short-term comfort of the living.

No. Some people survive and doctors have a moral and ethical obligation to not throw their hands up in the air. Furthermore, without informed consent or advance directives, it's unfair and unethical to play god.

The circumstances of this situation is that ventilated COVID patients often drown in their own plasma, get bacterial pneumonia or their lungs are irreparably destroyed. Like ECMO, this sort of ventilation is a hail mary procedure to try to salvage patients.

Even COVID survivors with mild symptoms, they may have reduced lung capacity due to lung damage.. and that may well be permanent. I suspect lung transplant lists will be backlogged the world over due to this pandemic.

A doctor's job is to play God. There is no neutral choice.

Ventilation is not a very cruel intervention, especially since you will almost certainly be sedated. I've been intubated a few times, and I'd much rather take this than for example CPR which regularly breaks ribs.

It’s not a cakewalk for the elderly. I think some patients would want to remain communicative with loved ones rather than fade away unconscious over weeks.

We should be upfront about the odds of a full recovery and allow room for thoughtful discussion around patients’ wishes. The frenzied environment of ICUs during a pandemic isn’t conducive to this, so we need to be deliberate and talk about it as a country. The “job one is saving lives” rhetoric may not be best for patients and their families.

I’ve seen nurses and doctors on Twitter mention that “every patient needs to be fixated, as they experience a feeling of drowning or asphyxiation and try to remove the tube”

I’m not sure if that experience is caused by the ventilation, or by the disease and misattributed. In any case, I’ve decided not to get infected by this bug. And if I fail at that, I might even consider a living will excluding ventilation.

Are they intubating COVID-19 patients without general anesthesia? I've been in the hospital a month due to pneumonia and have been intubated 3 times. The second and third times they did intubation and extubation all under general.

The first time they put some kind of special tube in under general. When I came to 3 days later there was no ventilator, and the end of the tube was in my throat. It felt like a rectangular block. They extubated me while I was awake and immediately put me on high flow oxygen. They would've intubated me on the spot if I couldn't breathe. Never felt a gagging sensation in this instance.

it's a natural reaction to having a thing down your throat. i woke up in the ICU once with a tube in. my wrists were bound down so I wouldn't pull it out (which i would have, in my newly awakened stupor). once awake and lucid i was fine to have hands freed.

It is true, if you are conscious you will try to remove the tube (self-extubation), as it makes you gag. But that means that sedation is too low, which could be because they don't have time to monitor everybody.

And/or they have shitty monitoring equipment made by legacy players in an industry that needs disrupting. I mean yes there are staffing issues as well, but both can be true.

so, it seems like personel IS a bottleneck which is not going away by 3D-printing a million of ventilators.

I think that since building ventilators is very difficult and beyond the capability of the diy and foss communities and has a fairly low survival rate anyway, I think that we should focus on other ways in which we could help.

One way to help would be to aid physical containment. The first thing that comes to mind are online tools for communication, learning and doing basic daily life things. I think that there is still room for improvement.

The next thing comes to my mind is that people need to go out to buy food, medicine, etc. They also need to drink something and in some places water needs to be sanitized. Maybe DIY sanitizers are an option?

Food and other supplies might be bought online, but companies doing online sale and food delivery seem to have issues handling the load. I think that the biggest issue is finding drivers and delivery man to bring groceries do people's doors. Surely, self driving cars and trucks and robots taking packages and climbing staircase or using the elevator aren't an option, but I have other ideas.

People could order stuff through internet from their local shops and supermarkets and then pick them packaged in boxes from parking spaces or a drive through with store employees putting boxes in people's trunks or even a system where people go to a door with a belt, scan a QR code from an app, see the door open and their package arriving on that belt.

I remember that when the epidemic was starting, journalists reported that people rushed to shops and all the pictures of people with their carts filled with toiled paper standing very close to each other in a very long queue. To me it seemed like the best way of getting infecded.

I have many other ideas for 'improvements' and notice other 'mayor problems', but this comment is already way too long...

I hope that this isn't off topic in the ventilator thread.

Ventilating a patient with active pleural effusion (fluid in the lungs) is a finicky process. The vent alarms constantly, and the patient frequently needs to be suctioned, which is a team effort often involving several bedside nurses and a respiratory therapist. Even if we stock up our ventilator supply, I have no idea how we will get enough people to operate them effectively.

Pleural effusion = fluid around, but not inside of, the lungs. It is treated using thoracentesis. Suction = for removing secretions inside of the larger airways. Consolidation = fluid inside of the lungs, specifically within the alveoli. It prevents oxygen exchange and there is no specific procedure that can address it. Medical management focuses on tricks like proning that can increase ventilation to areas of lung that have less consolidation. If both lungs have consolidation in the majority of lung units, the patient cannot be saved even on a ventilator. In this case ECMO is a possibility, but ECMO resources are very limited and the lungs might not ever recover enough to start working again.

Brain fart — meant pulmonary edema, not pleural effusion. P-E something, anyway.

Thanks for the explanations.

Isn't there a way to oxygenate blood outside of the body like dialysis? Why isn't that used more?

Great question! You are referring to ECMO. The main limitations of ECMO come from the serious complications that can occur, which can include life-threatening bleeding, blood clots, infections, strokes, and brain damage. The number of hospitals in the US offering ECMO is in the low hundreds. It takes an experienced team to use it safely, and if used in the wrong patients, it can artificially prolong suffering rather than saving a life. However, it is still an amazing technology for some patients.

I was wondering this too. It seems like the problem would be the rate of oxygenation of the blood is too high for any current machine to handle and something completely new need to be designed

My spouse is in anesthesia and is currently training dozens of PACU nurses every day on how to operate anesthesia machines and vents for this eventuality. Obviously they won't be providing ideal care, but many hospitals are working on "leveling up" any and all staff that can be trained. Crazy times we're living in.

> I have no idea how we will get enough people to operate them effectively.

Yes, we don't have enough ventilators. But we have more ventilators than what our currently trained staff can operate.

But that isn't a problem that excites engineers.

Actually that seems kind of exciting: making ventilators that don't need highly trained staff to operate. But maybe I'm just weird that way.

But you can’t know what is in another person’s head.

There are some all-in-one ventilators, which automatically suction too, but I guess they are not wide spread:

> VOCSN integrates five separate medical devices, including a ventilator, oxygen concentrator, cough assist, suction, and nebulizer, into one multi-function ventilator.


While I'm genuinely thrilled to see this on the front page, this article is incomplete and inaccurate.

First, mucus is protective of the lungs. Personally, I don't believe there really is such a thing as "too much mucus."

As someone with chronic lung problems, I cough up less crap when I can keep mucus production up. So I think that if you have junk in your lungs, it's phlegm, not mucus.

They can be hard to tell apart. The difference is phlegm is basically infected drainage, sort of like the lung equivalent of pus.

Salt and fluids are the two main components of mucus. To support mucus production, you should stay hydrated and get enough salt.

Second, there are other ways to improve lung function in the face of pneumonia and inflammation. Many of these methods are medically prescribed and used daily by people with serious, chronic, incurable lung conditions, such as cystic fibrosis.

I have talked about this before. I don't really want to harp on it or argue with people.

I'm not a doctor. I'm just someone who has a form of cystic fibrosis, so management of serious lung issues is a daily part of my life.

Please see some of my previous comments for additional info:


I would hesitate to write that "too mucus" is not an issue, because too mucus can cause a lot of problems for your lungs. For example, individuals with chronic bronchitis have hypertrophy of the mucus glands relative to the bronchial wall (look up Reid's index). This leads to mucus plugging within smaller alveoli and subsequent cyanosis and hypoxemia. Moreover, the obstruction due to the stasis of mucus can lead to the formation of purulent material/inflammatory necrosis (bronchiectasis) as well as damage to the mucociliary escalator. In fact, this mucus trapping is an underlying cause of the respiratory symptoms you see in cystic fibrosis and several other respiratory diseases. *I would add that in CF, the formation of the mucus is fundamentally impaired, causing it to be less effectively cleared.

I've stated as clearly as I can that this is my personal opinion and what that personal opinion is based on.

I am aware of the official explanation for CF and have noted what it is in another comment of mine in this same discussion.

I am not actually looking to get into some long tangent concerning my opinion about how CF really works. It's irrelevant to this discussion.

If you don't care for my personal opinions about how this works, please just focus on the takeaway that "non mechanical air clearance methods exist and are medically prescribed" and please seek out official medical sources of information on airway clearance, which Italian doctors are apparently using in cases not serious enough for a ventilator.

COVID kills by drastically reducing the surface area that can be used for oxygen exchange in the lungs. The successful protocols are more in line with dealing with a drowning victim than long term maintenance of someone with reduced lung function.

The official explanation for cystic fibrosis touted by the Cystic Fibrosis Foundation is that people with CF are "drowning in their own mucus."

Airway clearance is medically prescribed and it's not because we tend to have big holes in our lungs from repeated infections. It's because we tend to have too much gunk in our lungs.

Reduced lung function per se for people with CF is typically due to the lungs being eaten away by infection. The end game for medical treatment of that issue is typically lung transplant. People with CF account for about a third of all adult and half of all pediatric lung transplants in the US, or did the last time I looked up such stats.

What's interesting is I knew about cpap machine (I mean everyone does from the ads for "sleep equipment" right?) but I didn't know there is also bi-pap machines which may be suitable for some with covid19.

Some also get away with just taking in oxygen, I guess at the hospital they have to evaluate and monitor.

> infection that leads to the lungs filling with fluid

> The ultimate goal with these three things is to give the patient time to develop antibodies and fight the virus and clear out the lungs

Where does the fluid come from in the first place? Do the viruses (I can hardly believe) or bacteria produce it? Doesn't the patients own body do? If it does then why and how? Can that be inhibited?

The patient’s own body makes the secretions. It’s a combination of leakage from damaged cells in the lungs caused by the virus, and the natural immune response. Since the infection is inside the lungs, producing mucus is the body’s way to try to encapsulate and expel contaminants, and also provides a liquid medium for antibodies and white blood cells to circulate in.

With covid-19 and flu, you generally don’t die from the effects of the virus, you die from the side-effects of your own body’s immune response.

Really shows you how complicated things are. I wonder if I'm given enough time if I would be able to do a full solution that I would be willing to use on myself... I don't think I would... I don't think in all honesty any single person would...

Question: is it possible to oxygenate blood via IV (similar to how toxins are removed via IV in dialysis)? When babies are in the womb they get oxygen without using their lungs.

ECMO? That's even more complex and resource-intensive than ventilation, with its additional share of thorny issues. I think ECMO is indeed being used to mitigate this outbreak, but the equipment is even scarcer than ventilators and it only really makes sense for patients in extreme critical condition.

Yes, they do this for https://en.m.wikipedia.org/wiki/Cardiopulmonary_bypass but it’s massively invasive.

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