2 ms·

Neat idea, though I think it will be quite some time before it produces something that people can build or use. Another option might be to figure out ways to a

by ggreer 7y ago

Neat idea, though I think it will be quite some time before it produces something that people can build or use. Another option might be to figure out ways to adapt existing ventilators to be used by multiple patients. If you find 4 patients with similar tidal volumes and body size, you can grab some Y tubing, attach them to the same ventilator, then set it to 4x the tidal volume and breathe for all of them. This has been studied before[1] and was done in at least one mass casualty event[2]. The main disadvantage is the risk of spreading germs (though the air return hose is separate from the incoming hose, so that shouldn't be too much of a problem) and the fact that patients sharing a ventilator require more careful monitoring of blood gasses.[3] I doubt patient outcomes will be as good as having one ventilator per patient, but if it can increase our capacity by 4x overnight it seems worth pursuing. 1. https://www.ncbi.nlm.nih.gov/m/pubmed/16885402/ https://www.ncbi.nlm.nih.gov/m/pubmed/16885402/ 2. https://epmonthly.com/article/not-heroes-wear-capes-one-las-vegas-ed-saved-hundreds-lives-worst-mass-shooting-u-s-history/ https://epmonthly.com/article/not-heroes-wear-capes-one-las-... 3. https://www.resuscitationjournal.com/article/S0300-9572(08)00542-X/fulltext https://www.resuscitationjournal.com/article/S0300-9572(08)0...

tgsovlerkhgsel 7y ago
My understanding is that what a ventilator does is basically: - supply pressurized air to patient - turn off the pressure, open exhalation valve and let patient exhale Given that every hospital I've seen has compressed air outlets, wouldn't it be possible to get acceptable results with a pressure regulator and a timed set of valves? Or is the pressure required to fill a patient's lungs so high that the volume must be controlled?
- cameldrv 7y ago
  My layman's understanding is that ventilation is a fairly complex art/science, and that modern ventilators have multiple modes that are effectively different control laws. I think that the pressure required to fill a patient's lungs is quite different in a COVID patient than a normal patient, because the disease has caused huge flow restriction in the lungs. I think that generally you want to control flow rate, because you need to get a particular respiration rate, and the lungs can hold a certain amount of air. You then use whatever pressure gets that respiration rate. If the pressure or flow rate is too high, I think that that can cause lung damage, so one option is to increase the oxygen concentration in the air you're delivering. My understanding is that the downside is that although this will lead to more oxygenation, it doesn't help any with removing CO2. If you reach this limit, the only option is then ECMO.
  - loeg 7y ago
    > My understanding is that the downside is that although this will lead to more oxygenation, it doesn't help any with removing CO2. If your input is O2 (or O2+N, no CO2) and you run part of the pressurization cycle with the exhalation valve open, won't you displace at least some CO2 (not in tissue, just in the lung cavity)?

by ggreer 7y ago

tgsovlerkhgsel 7y ago

My understanding is that what a ventilator does is basically: - supply pressurized air to patient - turn off the pressure, open exhalation valve and let patient exhale Given that every hospital I've seen has compressed air outlets, wouldn't it be possible to get acceptable results with a pressure regulator and a timed set of valves? Or is the pressure required to fill a patient's lungs so high that the volume must be controlled?

cameldrv 7y ago
My layman's understanding is that ventilation is a fairly complex art/science, and that modern ventilators have multiple modes that are effectively different control laws. I think that the pressure required to fill a patient's lungs is quite different in a COVID patient than a normal patient, because the disease has caused huge flow restriction in the lungs. I think that generally you want to control flow rate, because you need to get a particular respiration rate, and the lungs can hold a certain amount of air. You then use whatever pressure gets that respiration rate. If the pressure or flow rate is too high, I think that that can cause lung damage, so one option is to increase the oxygen concentration in the air you're delivering. My understanding is that the downside is that although this will lead to more oxygenation, it doesn't help any with removing CO2. If you reach this limit, the only option is then ECMO.
- loeg 7y ago
  > My understanding is that the downside is that although this will lead to more oxygenation, it doesn't help any with removing CO2. If your input is O2 (or O2+N, no CO2) and you run part of the pressurization cycle with the exhalation valve open, won't you displace at least some CO2 (not in tissue, just in the lung cavity)?