If a diver with DCS is on air, how should you adjust subsequent air or oxygen stop times during recompression?

• A. Multiply subsequent air or oxygen stop times by 1.5.
• B. Double all stop times.
• C. Keep stop times the same.
• D. Shorten stop times by half.

Answer: (A)

During recompression for decompression sickness, the goal is to shrink bubbles and continue inert gas elimination. The breathing gas matters because nitrogen off‑gas is slower when a diver is breathing air than when oxygen is used. Because DCS has already started and bubbles are present, you want to give the body more time at each stop to let the treatment work and to prevent a rebound of symptoms. Extending subsequent stops by about 50% (multiplying the stop times by 1.5) provides a conservative margin to account for slower washout and ongoing bubble resolution, whether you're on air or oxygen during the treatment sequence.

Doubling stop times is more than typically required and could unnecessarily prolong the treatment; keeping stop times the same risks under-treating; shortening would be unsafe.