[fineright]

"So how common are hyperbaric chambers in trauma centers?"

Hopkins in Baltimore had two of them in 1983. One reason they told me was because drugs have an easier time getting into the bloodstream.
I got into a nasty accident on a bike and gotta helicopter ride to shock-trauma that year.
I needed a few operations to make things work again and I woke from most of those in the hyperbaric. I even had some hyperbaric therapy which was basically sitting in there for 2-4 hrs a day.
Seemed to work, I can walk again.

[MickMan51]

Seems to me that de-pressurization was not necessary because the conditions that necessitate it WERE NOT PRESENT. To wit, at an UNDERWATER depth of 250 feet below the surface, the (atmospheric) pressure on the body and the bloodstream is VERY HIGH. At 250 feet below the surface of the earth, with ventilation shafts to the surface, THE ATMOSPHERIC PRESSURE IS NEARLY IDENTICAL TO THAT ON THE SURFACE. Pretty basic stuff.