Hello DrSteve:
Hydrostatic Pressure
Pressure can indeed cause all manner of nasty things. When the body is subject to uniform increased pressure, however, the situation is a bit different. There are not any fluid shifts with uniform pressure over all body.
Remember that we are at the bottom of an ocean of air and subject to 14.7 psi at all times. An average individual has a body surface of 19.4 sq. ft, and with one atmosphere of pressure, this equates to 41,000 pounds on the entire body. This is a very large force, but it is applied equally.
The pressure on an individual in a pressure chamber, or a diver in the water, is also applied evenly. There is not any shift of fluid from this. Id you were to stick your hand into some small pressure chamber with a suitable seal around the arm, pressurizing this would cause the blood to be squeezed into the body from the extremity.
Bed Sores
In the cause of decubitis ulcers [bed sores], the individual is lying on parts of the body and preventing adequate perfusion. Sores develop because the person never moves around, as do you or I. People in such situations must be turned do prevent this problem.
Dr Deco :doctor: