DCS Effects FAQ

Why do the effects of decompression sickness (DCS) last longer than the 12 to 18 hours it takes to offgas? Do the bubbles that cause DCS lead to other problems in the body that last longer? If that's the case, why are chamber dives effective in easing the symptoms of DCS even after a day or more has passed and the level of inert gas in the body is no longer elevated?

DCS can manifest in many ways, and the signs and symptoms depend on the body system or systems being affected. DCS usually involves large numbers of small bubbles, and their effects include mechanical tissue damage and the interruption of blood flow to some areas of the body. Irritation can occur in the endothelium (the cells lining blood vessels), which leads to inflammatory responses that may cause platelets to initiate clotting and white blood cells to accumulate. The inflammation and tissue damage take a while to heal, which is why DCS lasts longer than the time it takes to eliminate inert gas.

Hyperbaric oxygen therapy (HBOT) can be effective for days or even a week or more following a dive because HBOT has significant anti-inflammatory properties and oxygenates injured tissues, thereby promoting healing. HBOT is frequently administered after the tissue damage, inflammation and other injuries have occurred and no inert gas remains; in these cases its purpose is only to promote healing. However, HBOT administered very soon after the injury also promotes the washout of inert gas.

Scott Smith, EMT-P, DMT