What is the recommended action if you suspect in-flight decompression sickness?

• A. Descend but do not provide oxygen
• B. Keep cruising altitude and monitor symptoms
• C. Land immediately without notifying anyone
• D. Administer 100% oxygen and descend, notify flight deck, and request medical assistance immediately.

Answer: (D)

When in-flight decompression sickness is suspected, the immediate priority is to support oxygen delivery and reduce bubble formation. Administer 100% oxygen right away to maximize nitrogen off-gassing and improve tissue oxygenation. At the same time, descend to a lower altitude as quickly and safely as possible to increase ambient pressure, which helps shrink existing bubbles and accelerate recovery. Don’t delay descent for other actions. Notify the flight deck and request medical assistance immediately so the crew can coordinate a possible diversion and arrange ground-based medical support or emergency evacuation if needed. Early treatment with high-flow oxygen and rapid descent significantly improves outcomes and reduces the risk of progression.