Can Saunas Prevent Decompression Sickness?

By adhering to conservative profiles like slow ascents, extended safety stops and appropriate surface intervals, the healthy, fit diver faces only minuscule risk of decompression sickness (DCS). Still, much has yet to be proven about the exact causes of DCS. According to a recent study, a long sit in a hot sauna may help to prevent it.

In their article published in the journal Aviation, Space and Environmental Medicine, researchers from France had 16 military divers take a 30-minute dry sauna heated to 149 degrees Fahrenheit. An hour later, the divers took a simulated dive to 98 feet in a hyperbaric chamber. Then, everyone did the same dive without sitting in the sauna beforehand. Post dive Doppler readings found that circulating bubbles were reduced by about a third in divers who had done the sauna/dive procedure. They also had significant reductions in systolic blood and pulse pressures.

Researchers opine that the decrease in inert gas bubbling may in turn decrease the risk of DCS. Possible reasons include changes in plasma heat shock protein and nitric oxide levels, and sweat dehydration. However, the findings can only be considered suggestive for the time being.

Even if these findings are replicable, various temperature levels will need to be tried to see if lower temperatures can produce similar results. There’s really no workable way to subject the body to temperatures in the 150-degree range other than by dry sauna (wet environments at that level would cause burns). If the reported reduction in gas bubbling in fact does require temperatures at or near this extreme, you’d be out of luck if you don’t have access to a sauna heated to this temperature range.

As a final caution, it’s important not to confuse pre-dive with post-dive sauna, or even with post-dive hot tub, shower or other methods exposing the body to high temperatures. Excessive heat after a dive can accelerate inert gas elimination and increase bubble formation, and so should be avoided. Besides deep stops and slow ascents, spending your first hour of post-dive time in a warm, but not hot, setting is another way to keep DCS at bay.

- - Doc Vikingo

“Predive Sauna and Venous Gas Bubbles Upon Decompression from 400 kPa,” by Jean-Eric Blatteau, M.D. et al.; Aviation, Space and Environmental Medicine, December 2008.