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Comment by malandrew | Hacker News Reader

Because they are not the bottleneck. Intensivists that can operate the vents are the bottleneck

https://sccm.org/Blog/March-2020/United-States-Resource-Avai...

That is some bureaucratic nonsense. Setting up and maintaining a ventilator is not rocket science, you can train other staff to do that job pretty quickly.

Ancillary tasks may suffer from staff shortage, but if you need one, getting a ventilator and minimal care is a lot better than not getting a ventilator.

Any guides to how to set up a ventilator by chance? Asking for a friend...

Very short guide: Put a mouthpiece on the patient, connect the mouthpiece to the tube from the ventilator, turn the ventilator on.

Longer guide: Read the manual for the specific ventilator and have fun adjusting air mixture, pump frequency, pressure, volume and other stuff. Choose one of several different models of mouthpiece, with or without tubes, depending on patient needs. Learn about different failure modes and associated alarms. Learn how to operate the pump manually in case of electronics failure. Learn how to properly clean the machine.

It isn't nothing, there are some things you can do wrong if you don't know what you are doing. But a trained medical professional should get up to speed with a crash course.

The type of ventillators required by the most serious cases are much more complicated: as I understand it, it involves push a tube down to the lungs, and the machine breathing instead of the patient, i.e. it has to carefully monitor and regulate the pressure etc. Already the "push tube down to the lungs" part is quite a challenge: avoiding damage to the vocal cords, or to the lungs, etc.

Should we then not be damn sure that there are shitloads of the simpler ventilators so that the complicated ones can be fully reserved for the serious cases?

In the hospital they’re all complicated cases. The simpler vents are for home care use. The hospital doesn’t typically do noninvasive ventilation because it’s meant for patients who are awake and outside of a hospital setting.

Tubes down the lungs is definitely a bit tricky, not all patients will require that model though. As for careful monitoring, that is something the machine does on its own, as long as it has been configured correctly for the individual patient.

This is incorrect on many levels. A ventilator always requires intubation. Sometimes that's through the mouth, sometimes through the nasal passage (both cases are referred to as endotracheal), and rarely through a tracheostomy. Ventilators do have some monitoring capability, but require consistent attention from respiratory therapists. The chances of infection (VAP), pneumothorax etc are serious without careful monitoring by a trained, experienced medical professional. These aren't plug and play devices.

Some patients might need supplementary oxygen delivered through a canula, or through a mask, but that's nothing like the procedure used for a vent.

A ventilator always requires intubation

Can you elaborate? This ventilator documentation[0] says for invasive and noninvasive ventilation

[0] https://www.usa.philips.com/healthcare/product/HCNOCTN98/res...

Many vents can also operate in BiPAP or CPAP modes or as pure demand O2 supplies for people who can still breathe. That can be done with a mask.

When treating bilateral interstitial pneumonia, you're almost always intubating. Patients presenting BIP require higher oxygenation than a CPAP style mask can provide. Using a limited availability ventilator with just a mask is a waste at this time.

I don't know how to operate a ventilator, and have zero medical training, but I'm getting frustrated by the comments claiming medicine is trivially easy.

Even using a syringe or blood draw on a patient is something one needs certification to do properly. That isn't bureaucratic nonsense. Having worked with syringes and sterile technique, there are so many ways you can give your patient an infection or otherwise cause them life-altering complications if you don't know what you're doing, even for the actually trivial techniques. Operating a ventilator incorrectly will result in death. Likely a grisly one, as incorrect pressure differentials and human lungs are not a good combination.

Now that doesn't mean we need to stick to these bureaucratic rules as they are for this situation, but the people on here advocating for trying complicated medical procedures while knowing fuck all about medicine (or even biology) really need to take a step back and take an inventory of what they don't know, and can realistically expect to accomplish with neither the technical knowledge nor manual dexterity of a trained clinician. A YouTube video and a technical manual aren't going to cut it, folks.

I'm not suggesting that you or I operate the ventilators, but I refuse to believe that hospitals can't get someone decently qualified to do the job. If the need arise, those 160000 ventilators will be in operation in a heartbeat. The only reason not to get more is if you believe that there won't be that many patients.

I am getting frustrated by the comments that miss the big picture. There are likely going to be lots of people that are going to die without ventilator. Now, who with any common sense and decency[1] cares if 30% of them are dying because the device was not used properly/broke/whatever if the only other available option is that 100% of them die?

[1] Sigh... I know, I know. American lawyers and legal system.

The thing you’re missing is these new RTs wold not just be treating COVID-19 patients. There are tons of people who will need ventilator therapy because they were injured or sick and they would have gotten injured or sick anyway. These are people who can be saved with proper treatment or injured by improper treatment. Barotrauma and lack of tidal volume have implications beyond simply alive or dead. We need people but we must make sure they can actually provide adequate treatment.

In your example, a 30% mortality rate is a very big deal. If we had a hypothetical cure that killed 30% of the people it was administered to, I doubt it would get very far.

I'm not saying the alternative is do nothing. But playing doctor because you think that you're reasonably qualified to administer a ventilator, then we're going to end up with, say 30% mortality rates from patients whose lungs were sucked through a ventilator tube because you guessed the wrong pressure. Or, more realistically, a terrible infection because you decided soap and water in the bathroom sink would be sufficient to clean the apparatus.

And then what do you suppose will happen after 30% of these amateur medical procedures go South? Are you going to throw in the towel, try something even more reckless, or decide that you need to get an actual doctor involved to clean up your mess? At which point, you've just added yet another case to the already overburdened medical system. And at a 30% failure rate, that would become a major burden.

There's a lot of room for action between doing nothing and acting foolishly (such as claiming a 30% mortality rate for botched medical procedures is a rational tradeoff). There are ways to help the situation here that don't involve magically becoming a nurse overnight.

I'm sure the hospital nurses can learn via on-the-job training in a day. This is an emergent situation. No one is suggesting pulling a random person off the street to do it

I was reading some accounts on /r/nursing that its relatively complex. The issue you have is that its quite easy to kill a patient if you fuck it up and there are multiple factors that impact the operation of the machine (e.g. patient weight for example).

Setting up a ventilator for treating ARDS (caused by the viral infection and inflammatory response) is at the much harder end of respiratory therapy unfortunately. This is also one reason why just building the simplest possible ventilator simply isn't possible / useful here. Yes you could basically build a 1960s design en-masse but at the moment 50% of people on modern vents are surviving so this is no panacea.

The trick will be to find a minimal feature set design, that doesn't use a lot of specialist long lead time components, can be used by people who are less experienced, and is suitable for treating ARDS. That is a much harder problem than the basic one of getting some kind of ventilator mass produced on an emergency basis.

That minimal feature set is a CPAP machine + maybe an oxygen valve of the 3D printable variety.

Modern CPAP machines can generate phenomenal pressures and can be adjusted with simple touch screens. They support automatic pressure reduction on exhalation, and Bluetooth/cloud access to the data in them for remote monitoring via mobile apps.

BTW it's not quite as simple as 'hospital ventilators are hard to use'. Firstly, modern ventilators are much easier because the manufacturers realised that high training costs were limiting their market, so they've got a lot easier to use. Secondly, the US did a previous disaster response training exercise where they trained a bunch of non-specialist medical staff like nurses and even vetinarians how to use the machines. After 2 days of training there was an exam: the vets did best.

CPAP machines generate continuous positive pressures though, they assist breathing. I know they have slow ramp capabilities for comfort reasons (start off at low positive pressure when you fall asleep and then increase) but I don't think they can swing pressure fast enough to enable inhalation and exhalation.

You need: -Gas blending (relatively trivial) -A source of pressure (CPAP has this) -A way of modifying pressure up and down quickly and precisely enough to stimulate breathing (Don't think CPAP has this) -A way of measuring flow and pressure (Does CPAP have this with good time resolution? I doubt it as not required for CPAP) -A controller which uses the flow and pressure data to vary the system pressure (CPAP doesn't have the right software but presumably this is less time constrained than the others)

So I'm really not sure that you can do this with a modified CPAP machine.

BTW I'm not sure that you can print oxygen valves, maybe air valves or patient valves. High pressure inlet oxygen parts need to be oxygen compatible and many 3d printed materials may combust under those conditions.

CPAP machines technically can't but CPAP has become a generic term that also encompasses bi-level/APAP machines that can swing pressure fast enough to track inhalation/exhalation. Both mine do. They're not that old but they're not top-end either.

I don't know how many active machines are pre-APAP/BiPAP/A-Flex (there are different names for it). A comment below says 90% but this seems very high to me.

I wonder if it's possible some doctors don't realise the machines have this feature or it's importance? When I first was prescribed CPAP the machine did not come with bi-level flex enabled, it made it very hard to tolerate. I pushed through it for months but when I "cracked" the doctor-only DRM (i.e. looked up the cheat code on Google) and enabled A-Flex it instantly became way easier to handle the machine and my AHI scores were super low; big success. Doctor was quite happy with my altered configuration. I was just surprised such a basic thing hadn't been explained to me.

I suspect a lot of CPAP machines support bi-flex but it either isn't activated or could be added via a software update. I don't think you need extra components.

Oxygen valves come from here: https://learningenglish.voanews.com/a/volunteers-produce-3d-...

Very interesting, thanks. If that is the case then it may indeed simply be a software thing. Specifically for treating ARDS you need:

-High PEEP (obviously any CPAP machine can do this)

-Low plateau pressure (probably possible, that's just software)

-Low tidal volume and high breathing rate. Breathing rate is just a cycling variable so should be software only issue. Managing low tidal volume will require the machines to have a flow sensor. Do you know if any of your machines do? If so, then this is likely fixable with only software.

My interpretation of that article is it must refer to the patient valve as those are one-time use (as they in contact with contaminated patient exhalations) rather than O2 inlet valves which are not disposable. Patients are breathing high-ish O2 but obviously not HP pure O2 so 3d printed is fine for that.

3D printing is useful for cases like that where due to logistics there is a temporary shortfall in local supply. I suspect that 3 months from now we are unlikely to be using those measures as global production and distribution of ventilator consumables ramp up.

Yes, they all have flow sensors. They track vast quantities of data, in fact they track and record the flow of every breath on SD card and can upload that data via Bluetooth.

There's an open source app called SleepyHead that can show you all the data in detail. It appears the maintainer burned out but the downloads are still available.

So it seems modern CPAP has all that's needed? Doctors can even monitor it remotely or via the cloud. It's intended to let clinics monitor patient progress without needing visits, so it's all pretty easy to use.

A CPAP is fixed pressure, what your thinking of is a APAP or the bilevel type of positive air-pressure machines. And there lies the problem with you're miniumum feature set; not all *PAPs are fully-featured machines. Maybe only 10% or so are suitable for ventilator duty, which means they too are supply-limited

I own two CPAP machines and yes they both implement bi-level/APAP features. CPAP is a bit of an ambiguous term these days; whilst there are technical differences between them, most people call all such devices CPAP machines. For instance,

https://www.usa.philips.com/healthcare/product/HCNOCTN447/dr...

It's advertised as "CPAP & Bi-Level therapy".

To be clear, I'm talking about the ones that implement bi-level pressure. The difference is (as far as I know) primarily a matter of software; perhaps older machines can be upgraded if pricing/selling upgrades is taken out of the equation?

I've had my machines for I think a couple of years now and they were all bi-level from the start. I'm not sure when that started becoming standard or where you got that 10% figure from, you may well be right. But there are 300,000+ sleep apnea patients being treated in the UK alone. If even only 10% of them use modern machines (seems low given how much better bi-level makes it), that's still 30,000 portable ventilators available to be requisitioned at short notice. Sleep apnea patients don't have a critical need for them.

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