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How much of a factor is the (relatively) super low air pressure in an airplane at cruising altitude? Does this cause more or less severity wrt the amount of air
by rkachowski 5y ago
How much of a factor is the (relatively) super low air pressure in an airplane at cruising altitude? Does this cause more or less severity wrt the amount of air trapped in the chest?
- KineticLensman 5y ago>> Wallace did not deem a landing at the nearest airport in Delhi to be viable either, because the increase in air pressure during descent could also kill his patient, and thus the only option was to perform an immediate surgery
- rkachowski 5y agoThat does not talk about the complications of the air pressure environment on the surgery itself.
- robbiep 5y agoSo i'm not an anaesthetist and therefore I claim no high ground with regard to this rusty attempt at respiratory and gas physiology - When I read it initially I thought - that makes sense, but I just did the equations, and basically the thing you're worried about is that the pocket of air that is outside the lung is going to change volume significantly and lead to the worst case outcome, a tension pneumo. But the volume of air outside the lung is going to be at cabin pressure, since that's where it developed. Cabin pressure is ~75kPa. Ground pressure is ~100kPa. The lung is going to exert more pressure than the gas so if you plug all that into boyle's law then you get a 75% reduction (or actually, you don't need to plug it into a calculator, because if you can't work out the percentage of 75/100 you're in trouble, so zero points to me). which would improve/stabilise. However maybe they were concerned the change in pressure could lead to a disequilibrium between lung pressure and potential space (of which there is always some due to breathing, and that sucking pressure into what should be a vacuum is what caused the pneumothorax - air leaking through a disruption in lung tissue) - and because the pressure differential is in favour of a flow into the low pressure zone, and that differential has increased, they're worrying about it shifting materially in a matter of minutes which could get bad quickly (particularly when you consider the potential for any leakage to become progressive, rather than, say, self-limiting) I don't know enough of this sort of edge case medicine to make any sort of definitive statements but if that was the physiology, maybe they decided it was out of the question to risk it --- I just realised I didn't really answer your question - which relates to, i guess, basically being at cruising altitude as it develops. Because it's steady state (ie inspired air/atmospheric air is going to end up similar pressure to trapped air) basically not significant in terms of progression until you get to blood oxygenation thresholds - because there's a lower partial pressure of O2 in cabin air compared to on the ground, the decreased lung volume is going to cause these issues to become apparent more rapidly. So it shouldn’t affect progression/growth of the pneumothorax, but it will exacerbate the physiological deterioration