Doctor I talked to said that this was 30% of patients
You probably need around 5L/min of 90% O2, which theoretically requires a medical grade condenser that requires a prescription. I, however, see no reason why getting 5 normal O2 condensers that can deliver 1L/min of 90% O2 and connecting them all with Y junctions won’t work.
[Edit: you can probably do with 4L/min of 70% O2, so you’ll need 2 O2 condensers. This advice is mostly based on priors and like 20 minutes of research. The crucial point is that you’ll likely need at least 2 O2 condensers]
These devices should all be relatively easy to use. Many people use a bipap for sleep apnea. Many people with respiratory problems have their own O2 condenser that they use. The capnometer I’m less sure of, but there should be a simple flow chart on what to do. If there isn’t, I will make one by talking to doctors.
The reason you need the capnometer is because giving people too much O2 also has its own host of problems.
This model assumes that there is 0 hospital capacity and it’s only for 1 person. Model also doesn’t take into account reduce quality of live because of the chance of chronic fatigue syndrome. Model also assumes 20% chance of getting COVID, which is pretty low. Disjunctions are more probable, so the value goes up rapidly with more people, but has a max because it can only be used on one person at at a time.
Bear in mind that the probability that a 2nd person you care about getting COVID conditioning on 1 person you care about getting COVID is pretty high because the people you care about hang out together.
The total cost is about 2k for the bipap, 5 * 400 for the O2 condensers, and 1k for the capnometer for 5k total.
If you think that more than 10% of the world is going to get COVID, buying 1 such setup for like 20 people is an obviously correct move given the model.
Things to watch out for: cheap chinese models of both of these devices.
Edit: took Daniel Filan’s suggestion of adding Y juntures and tubing to the first line.
Do you have any thoughts on where to buy a bipap and a capnometer? Can you get them without a prescription? Are they sold on amazon? If you or anyone else manages to get this to work (or even just starts buying supplies for it), I’d love to know where they obtained all their supplies and what they ended up needing.
no, we got BiPAP and even some HFNC equipment, but didn’t use / returned it within a couple of months when it became apparent that there wouldn’t be severe hospital overcrowding
There is a 5% chance of getting critical form of COVID (source: WHO report)
That’s a 40-page report and quickly ctrl-f:ing “5 %” didn’t find anything to corroborate your claim, so it would be helpful if you could elaborate on that.
13.1% have severe disease [...] and 6.1% are critical. [...]
Severe cases are defined as tachypnoea (≧30 breaths/ min) or oxygen saturation ≤93% at rest, or PaO2/FIO2 <300 mmHg. Critical cases are defined as respiratory failure requiring mechanical ventilation, shock or other organ failure that requires intensive care. About a quarter of severe and critical cases [i.e. about the number of critical cases] require mechanical ventilation while the remaining 75% require only oxygen supplementation.
As far as we can tell, these proportions for severe and critical symptoms are at hospital admission. Mark I first made this estimate here; we have updated downwards since then on estimates of untreated mortality on weak evidence that the current international strain is less severe than Hubei’s, and slightly upwards as testing in China and other East Asian countries becomes more thorough with fewer additional mild cases than we thought.
Also note that the 70% mortality without a ventilator/o2 for critical cases was assuming the basic medical care of an overcrowded hospital, even if equipment is not available. Medical care for pneumonia is primarily supportive, but doctors I’ve talked to say there is significant risk of developing complications like sepsis that require admission. This introduces more uncertainty into our estimates due to the number of moving parts.
I’m also interested in estimates for this number. I’m very confident that 4-5% is the right ballpark for total number of infected people who are going to need hospital care, but unsure about whether there’s a lot of age-related skew or not. I’ve seen people say that hospitalization doesn’t come with a large age-related skew, which would be alarming (for young people) indeed!
Hi Mark and others, thanks for sharing this info. Two questions:
1. When using the O2 concentrator, can we test for oxygen levels using Pulse Oximeter instead of capnometer? Looks like we need a prescription to buy a capnometer.
This paper finds that “During PSA in adults breathing room air, desaturation detectable by pulse oximeter usually occurs before overt changes in capnometry are identified.” :
2. In the WHO report, they say: ” About a quarter of severe and critical cases require mechanical ventilation while the remaining 75% require only oxygen supplementation. ”
In the cases where only oxygen supplementation is indicated, will an O2 concentrator suffice, or do we need a Bipap as well?
Mark—any thoughts on producing a system like this in crazy scale (say 10-100K/month) for altruistic purposes (i.e., to save lives not to make money)? Please DM me if you’d be willing to discuss.
(EDIT: ignore this paragraph, it’s not true) I’ve seen this discussed on another forum. Apparently, medical grade condensers require the patient to be put in a pharmacological coma so that their body doesn’t fight all that air being shoved down their lungs. Makes sense since usually only stuff that’s potentially harmful requires prescription.
Also, I’ve seen open discussions in at least one democratic country of confiscating privately owned condensers for the public healthcare. So if you end up buying some equipment, you will want to keep your mouth shut and perhaps use cash if possible.
I’m confused by what you mean by “medical grade condensers”. AFAIK, the type of condenser I’m talking about just delivers high oxygen content air through a nasal cannula or a face mask. I think you might be talking about ventilation, which involves shoving a tube down the patients throat and forcing high oxygen air in and out of their lungs.
Could you point me to where those discussions happened? I’d be interested in seeing whether government confiscation is likely to happen and maybe if I can make it more probable in some way. (I think that government confiscated currently unused oxygen concentrators and distributing them to hospitals is probably a very good thing.)
Thank you, you are right re. condensers. I confused them with ventilators. Re-reading this thread, it’s great to see that condensers alone greatly increase the chance of survival.
maybe if I can make it more probable in some way.
In that case I won’t assist you. I appreciate your honesty, though.
Buying a bipap + O2 concentrator + capnometer + Y juntures + tubing can decrease chance of death given being infected by about a third.
Reasoning:
Hospitals are going to be extremely overcrowded
Doctor I talked to said they would be in “big trouble” if even double the number of patients.
There is a 5% chance of getting critical form of COVID (source: WHO report)
Given you have a critical form and you cannot get access to a ventilator, there is a high chance that you will die (doctor I talked to have said ~70%)
For any ICU patient in a ventilator, there’s a non-trivial chance that that patient can survive with a bipap + O2 condenser
https://www.ncbi.nlm.nih.gov/pubmed/14720000
Doctor I talked to said that this was 30% of patients
You probably need around 5L/min of 90% O2, which theoretically requires a medical grade condenser that requires a prescription. I, however, see no reason why getting 5 normal O2 condensers that can deliver 1L/min of 90% O2 and connecting them all with Y junctions won’t work.
[Edit: you can probably do with 4L/min of 70% O2, so you’ll need 2 O2 condensers. This advice is mostly based on priors and like 20 minutes of research. The crucial point is that you’ll likely need at least 2 O2 condensers]
These devices should all be relatively easy to use. Many people use a bipap for sleep apnea. Many people with respiratory problems have their own O2 condenser that they use. The capnometer I’m less sure of, but there should be a simple flow chart on what to do. If there isn’t, I will make one by talking to doctors.
The reason you need the capnometer is because giving people too much O2 also has its own host of problems.
Here’s a model of the expected value of buying such a system for only 1 individual: (https://www.getguesstimate.com/models/15306)
This model assumes that there is 0 hospital capacity and it’s only for 1 person. Model also doesn’t take into account reduce quality of live because of the chance of chronic fatigue syndrome. Model also assumes 20% chance of getting COVID, which is pretty low. Disjunctions are more probable, so the value goes up rapidly with more people, but has a max because it can only be used on one person at at a time.
Bear in mind that the probability that a 2nd person you care about getting COVID conditioning on 1 person you care about getting COVID is pretty high because the people you care about hang out together.
The total cost is about 2k for the bipap, 5 * 400 for the O2 condensers, and 1k for the capnometer for 5k total.
If you think that more than 10% of the world is going to get COVID, buying 1 such setup for like 20 people is an obviously correct move given the model.
Things to watch out for: cheap chinese models of both of these devices.
Edit: took Daniel Filan’s suggestion of adding Y juntures and tubing to the first line.
Do you have any thoughts on where to buy a bipap and a capnometer? Can you get them without a prescription? Are they sold on amazon? If you or anyone else manages to get this to work (or even just starts buying supplies for it), I’d love to know where they obtained all their supplies and what they ended up needing.
I’m working with Mark to figure out the details. We’ll have an update within a few days if and when we find a working setup.
Was the update ever posted? I am interested in getting a capnometer for an unrelated reason and was curious where people decided to get theirs.
no, we got BiPAP and even some HFNC equipment, but didn’t use / returned it within a couple of months when it became apparent that there wouldn’t be severe hospital overcrowding
I guess people also need to buy Y junctures and tubing? If so, worth putting that in the first line IMO.
That’s a 40-page report and quickly ctrl-f:ing “5 %” didn’t find anything to corroborate your claim, so it would be helpful if you could elaborate on that.
Here’s the quotes we used; from pages 12 and 32.
As far as we can tell, these proportions for severe and critical symptoms are at hospital admission. Mark I first made this estimate here; we have updated downwards since then on estimates of untreated mortality on weak evidence that the current international strain is less severe than Hubei’s, and slightly upwards as testing in China and other East Asian countries becomes more thorough with fewer additional mild cases than we thought.
Also note that the 70% mortality without a ventilator/o2 for critical cases was assuming the basic medical care of an overcrowded hospital, even if equipment is not available. Medical care for pneumonia is primarily supportive, but doctors I’ve talked to say there is significant risk of developing complications like sepsis that require admission. This introduces more uncertainty into our estimates due to the number of moving parts.
I’m also interested in estimates for this number. I’m very confident that 4-5% is the right ballpark for total number of infected people who are going to need hospital care, but unsure about whether there’s a lot of age-related skew or not. I’ve seen people say that hospitalization doesn’t come with a large age-related skew, which would be alarming (for young people) indeed!
Hi Mark and others, thanks for sharing this info. Two questions:
1. When using the O2 concentrator, can we test for oxygen levels using Pulse Oximeter instead of capnometer? Looks like we need a prescription to buy a capnometer.
This paper finds that “During PSA in adults breathing room air, desaturation detectable by pulse oximeter usually occurs before overt changes in capnometry are identified.” :
https://www.ncbi.nlm.nih.gov/pubmed/20880431
So, a pulse oximeter should suffice?
2. In the WHO report, they say: ” About a quarter of severe and critical cases require mechanical ventilation while the remaining 75% require only oxygen supplementation. ”
In the cases where only oxygen supplementation is indicated, will an O2 concentrator suffice, or do we need a Bipap as well?
Mark—any thoughts on producing a system like this in crazy scale (say 10-100K/month) for altruistic purposes (i.e., to save lives not to make money)? Please DM me if you’d be willing to discuss.
Open Source Hardware guide for coronavirus
https://coronavirustechhandbook.com/hardware
Hand operated ventilators
https://www.notechmagazine.com/2020/03/open-source-breathing-ventilators-covid19.html
(EDIT: ignore this paragraph, it’s not true) I’ve seen this discussed on another forum. Apparently, medical grade condensers require the patient to be put in a pharmacological coma so that their body doesn’t fight all that air being shoved down their lungs. Makes sense since usually only stuff that’s potentially harmful requires prescription.
Also, I’ve seen open discussions in at least one democratic country of confiscating privately owned condensers for the public healthcare. So if you end up buying some equipment, you will want to keep your mouth shut and perhaps use cash if possible.
I’m confused by what you mean by “medical grade condensers”. AFAIK, the type of condenser I’m talking about just delivers high oxygen content air through a nasal cannula or a face mask. I think you might be talking about ventilation, which involves shoving a tube down the patients throat and forcing high oxygen air in and out of their lungs.
Could you point me to where those discussions happened? I’d be interested in seeing whether government confiscation is likely to happen and maybe if I can make it more probable in some way. (I think that government confiscated currently unused oxygen concentrators and distributing them to hospitals is probably a very good thing.)
Thank you, you are right re. condensers. I confused them with ventilators. Re-reading this thread, it’s great to see that condensers alone greatly increase the chance of survival.
In that case I won’t assist you. I appreciate your honesty, though.