Theoretically, could there be PAP-pods ? (whole body pressurized sleep)

[DaveCar]

Sci-fi movies where people stasis in those whole body bed "pods" got me wondering..

Would a slightly pressurized pod do the same thing as a cpap ?
A cpap is just making a force in your airway, but it's pressing against flesh to do its work right ? (as opposed to trying to inflate the lungs directly aka ventilator)

[Sleeprider]

Great idea. We can return to the 1950 iron lung! There is a reason that positive air pressure machine support both spontaneous respiration that most people need, and can also provide respiratory assistance as needed by individuals with pulmonary disease or central apnea. Invasive ventilation is not something anyone on this forum would choose to experience.

[Geer1]

No a pod would not be the same. Pressure is more effective when applied only to your airway, if you apply that same pressure to the exterior then it it is actually counter productive.

The easy way to think about this is to think of a balloon. A balloon inflates because of differential pressure. If you blow into the balloon it applies pressure to the inside of the balloon and it expands. If you blow into a container that has a balloon inside of it the pressure inside the balloon is the same as the outside and the balloon will not expand.

In short if you supply pressure into the airway via cpap then it works to expand airway. If you apply the same pressure to the outside of the body then it compresses the body which can actually make it harder to breath (because surface area on the outside of body is larger than the surface area on the inside of airway).

A ventilator is different from CPAP not because of how it supplies pressure but because it varies the pressure applied. A ventilator applies high pressure which inflates the lungs and then it decrease the pressure which deflates the lungs and it does this repeatedly forcing air in and out of the lungs regardless of what your body is doing. CPAP on the other hand is meant to provide pressure only rather than a change in pressures. The middle ground is a bilevel machine which provides some pressure differential (pressure support) albeit not enough to sustain life if your body is not trying to breath on its own.

The iron lung sleeprider mentioned is similar to your idea although it operated by creating a large pressure differential that compressed and expanded your chest/airways forcing you to breath. It has since been replaced by current ventilators which are more efficient because they only focusing on expanding and contracting your airways rather than a whole pod.

Hopefully that makes some sense. Another way to think about this is if you have ever been scuba diving. As you go deeper the pressure on the outside of your body increases making it more difficult to breath, not easier because your body has to work harder to overcome the external pressure pushing in on it.

[DaveCar]

Okay. So then I thought, would altitude not be a good proxy for the 'pressure-pod' thing ?
Found a study where people tested in Colorado (7900 asl) then again at sea level.
The 5 person group AHIs dropped from 53 to 33.
But,  unless the web calculators I used were wrong, here's the math;
7900' asl = 10.42psi  20' asl = 14.68 psi.  Difference = 4.3 psi , which is about 300 cm of H2O.

So, looks like it was good that I didnt buy pressurepods.com too soon.  lol

I like thinking about things, even when it turns out to be a dead end.

[SarcasticDave94]

If we see the details on your sample of high altitude vs lower, I'm quite sure the difference in events will be almost all CA. Higher altitude adds CA in cases such as you've described.

The pod? For some reason, I thought of diving decompression chambers. I think it wouldn't do what you're after, as was mentioned by Geer1, there's no opportunity for pressure differentials. Unless I'm completely wrong, iron lungs use negative pressure, where PAP is positive. Something like decompression chambers I'm thinking operate with positive pressures as well. And these aren't just to decompress or recompress divers. There's been medical uses to pressurize the patient over atmospheric to treat various illnesses that affect circulatory issues.

[Geer1]

Unless I'm completely wrong, iron lungs use negative pressure, where PAP is positive. Something like decompression chambers I'm thinking operate with positive pressures as well. And these aren't just to decompress or recompress divers. There's been medical uses to pressurize the patient over atmospheric to treat various illnesses that affect circulatory issues.

The iron lungs do use a vacuum. Kind of the opposite of PAP/ventilator but ultimately does the same thing. PAP applies pressure into the lungs which inflates them, iron lung creates a vacuum around body pulling body outward sucking air into lungs. 

Hyperbaric chambers are pods like the op was theorizing about and to step back a bit they could help against the effects of apnea but not in the same way as CPAP. Whereas CPAP helps by using pressure to hold your airway open a hyperbaric chamber could help by supplying more oxygen. Oxygen is commonly used to treat some cases of apnea (both with and without CPAP/bilevel).

[Sleeprider]

Altitude induced central apnea is kind of a special case, and a hyperbaric chamber could help with high altitude pulmonary edema (HAPE) and perhaps mitigate altitude related CSA. The conventional therapy for HAPE is return to altitudes below 8000 feet, and CSA is best addressed with a ventilator like ASV. Hyperbaric chambers are currently used mostly for decompression sickness / Caisson disease or the bends, as well as hyperbaric oxygen therapy.

[SarcasticDave94]

CPAP mask or hyperbaric chamber? Hehe, we thought getting the script for a PAP was tough, this will be impossibly difficult.

[archangle]

If  your head and body are both inside the chamber it won't do anything for apnea.  CPAP works because pressure inside your throat is more than the pressure on your body in general, and it inflates your airway in the area it collapses and causes apnea.  

If your whole body is receiving the same air pressure as your nose and mouth, there's no inflation effect on the airway. 

You might get some secondary effects that would help or harm, but in general, no, a whole body pressure chamber will not help apnea.

[DaveCar]

Im trying to come up with an analogy that seems right.

What if we brought an open balloon into a hyperbaric chamber, it would remain the same shape regardless of the chamber pressure. We could inflate the balloon, but it would require more absolute pressure to build up the same relative pressure.
What if we put a chunk of closed cell foam (maybe theres a more representative item, boiled egg ?) into the open balloon before entering the chamber ? The chamber pressure should shrink the foam a bit regardless of the balloon's inflationary state right ?
The balloon could still inflate/deflate, but the static pressure on the foam (soft palate) would remain relative so that the foam is either shrunk or shrunk more.

Not trying to be obtuse, just trying to get my head around it.