Posted by Gerry Smith on March 10, 2001 at 18:37:30:
In Reply to: Re: Lung Overexpansion posted by Steve on March 10, 2001 at 18:03:18:
Steve,
Yep, the 24 liter lung thing is correct. For the ten foot ascent question, each 10' will result in a 4.45 psi overpressure assuming you started with lungs filled to the max and closed your airway for the ascent. The relative part comes in when you examine the result of the 4.45 psi overpressure. If it occurred from 10 fsw to the surface, the lungs would have to accomodate about 30 percent more volume that they are designed for (4.45/14.7*100). If it happened at 100' (from 100 to 90 fsw) the extra volume is only about 10 percent (4.45/40.0*100). Now, MAYBE your lungs can handle 10 percent overpressure without damage but who wants to chance it?
These numbers by the way, assume that lungs are like balloons - they're not. They are more delicate. But the numbers give a pretty good approximation of the relative strain.
Gerry