hmmm, I'm a new nurse and not yet certified in this area (though I will be doing it after I complete my RN in 2010) I did, however, start teaching SCUBA in 1989 and have had a few familarization trips in chambers.
My own concern, and I need to research it more, would be about chronic effects of pressure on the body. You are in the chamber day after day, the patient is only recieving a one time course of treatment (I dont mean just one trip in the chamber, but the pt is done in a matter of hours, days, weeks max) you may be doing it for years.
Professional divers (not speaking to recreational scuba, but commercial divers that do deep dives day after day, or urchin harvesters who do loooong dives at shallow depths on consecutive days) do have higher incedence of a few things; bone necrosis, retinal and kidney damage. Most likely related to Asymptomatic Decompression Sickness. This is small nitrogen bubbles (and associated clots that form around them), but you don't have symptoms of DCS. With chronic exposure the bubbles/clots are believed to damage some of the areas in the body with the largest amount of capilarries/small vessels. In doppler U/S tests of divers up to 30% may show bubbles in the blood with no symptoms (asymptomatic DCS) after dives that are within commonly accepted no decompression limits.