Maximum Pressure for Human Lungs

Got it, and it makes sense. Thanks!

It will largely depend on the individual.

I can easily hit 2.5 - 3 PSI on a small 0 - 10 PSI digital gauge set I have.

Blowhards would be considered to be out on the far right of the bell curve, not the diving bell.

Way to go! That really is something you could brag about, though.

Internal, or external?

Internal, relative to ambient (nominal 14.7psi).

I.E. a safe pressure for inflating a collapsed lung is ≤ x psi.

Usually, pressure internal to the collapsed lung is not the problem. It is all the blood around it, inside the membrane that does not allow the lung to fill with air.

The S.O.P. is to puncture the membrane with a tube inserted to relieve the fluid pressure around the lung, and allow lung to begin filling again. If the lung is actually punctured, then a surgical repair is in order and is an emergency procedure to save the patient's life.

Almost right. Certainly any air or fluid in the pleural cavity (that space between the lung and the chest wall) needs to be drained out through a chest tube to allow the lung to expand. This is a more sensible procedure than trying to inflate the collapsed lung from the inside. However, even if the lung itself is punctured it is not always necessary to proceed to surgery. A small negative pressure in the chest tube may suffice to hold the lung against the chest wall and thereby to seal the leak.

Thank for for the clarification, as I am certainly no physician. I did stay at a Holiday Inn once, so I am qualified in conjecture.

What James Stewart just said.

This is no job for a bicycle pump, even in an emergency.

I recall a keen athlete who used to to do body building and other exercises - he used to blow or inflate hot water bottles by his breath or lung pressure. Hot water bottle is at least a millimeter thick plastic - I have no idea what pressure is required but this link may help.http://sploid.gizmodo.com/man-with-incredibly-huge-lungs-can-make-a-hot-water-bot-1618031822

Some think, they can just get away and blow lungs in a ventilator unnoticed as though there are no eyes watching. They really hope there is none watching, as though life is an accounted, but its POD for sure. Now, they laugh for a piece of little time and a little later they die for eternity.

What the ____ are you talking about? POD? Go read Proverbs, especially the part where it is good for man to work, rest, drink his beer, or wine, and not concern himself with deep mysteries for a time. Worship God, but do not judge man, you do not have the insight, the authority, nor the patience for that, only God can do God's job.

I knew there was a doctor in the house.

More than one, actually.

We had a discussion about this a while ago:

http://cr4.globalspec.com/thread/79066/Human-Lung-Air-Pressure

However, a definitive answer seems to have been given by phph001. I don't know about anyone else, but I'm throwing him a GA.

Some research into deep sea diving is appropriate....

For abrupt overpressure, as in a shockwave from an explosion...

'....The threshold for lung damage occurs at about 15 psi blast overpressure. A 35-45 psi

overpressure may cause 1% fatalities, and 55 to 65 psi overpressure may cause 99%

fatalities. (Glasstone and Dolan, 1977; TM 5-1300, 1990)....'

For the threshold for an aim embolism from excess pressure in lungs relative to outside body, as in forgetting to exhale while ascending having inhaled to capacity at greater depth on SCUBA.... the threshold can be pretty low, probably well under 10 psi, and likely less than the pressure one might developed to blow up a heavy balloon.

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For maximum pressure when equalized with ambient:

...breathing normal air, 20 atmospheres would incapacitate very rapidly and death would be likely without immediate assistance and facilities for recovery

....taking significant precautions and special breathing atmospheres, numerous people have survived moderate periods at pressures around 30 atmospheres. 40 atmospheres would present significant problems with getting enough O2 but avoiding O2 lung toxicity due to high partial pressure.

Aren't we simply talking about imploding or being crushed to death at those high pressures?

That seems ridiculously high. If that is external pressure, with ambient pressure in the lungs initially, the compression would crush a human body, I suspect.

If you are speaking of inflating lungs to such pressures, and having ambient 1 atmosphere pressure externally, I could not imagine the human body withstanding such internal pressure. CNS toxicity really, when the lungs would simply explode?

No, the chart has partial pressures of oxygen on the Y axis. Obviously you cannot have a partial pressure of >1 atmosphere unless the environment itself is at a higher total pressure, so the diagram relates to the situations of diving or hyperbaric chambers. I can confirm that we would use the data in this diagram in the management of patients in intensive care. Specifically we would not run 100% oxygen (1 atm at sea level) for 24 hours in patients with lung damage, as this causes irreversible further damage. The danger that a patient receiving high oxygen percentages in a hyperbaric chamber might suffer a seizure is well known.

How are you ready the Y -axis again? Is that the partial pressure in atm? Really?

OR is that factored where 1 = normal atmospheric breathing, and 2 is twice total atmosphere?

The chart is clearly labelled on the Y axis "INSPIRED OXYGEN PRESSURE, Atmospheres". This means it relates specifically to the oxygen pressure, i.e. the partial pressure. There could also be nitrogen in the mixture. If the ambient pressure is 1 atm then 1 atm of oxygen is 100% of the inspired gas picture. If the ambient is 2 atm then the percentage of oxygen is only 50%. The point is that the damage to the body relates not to the percentage but to the absolute pressure of oxygen.

OK, not planning on being in a hyperbaric chamber any time soon, or inflicting that on anyone, but knowledge is worth getting it right.