How does HBOT help reduce edema while preserving oxygen delivery?

• A. HBOT reduces edema by hyperoxic vasoconstriction while maintaining tissue oxygenation.
• B. Hyperbaric oxygen increases capillary hydrostatic pressure.
• C. HBOT removes fluid via diuresis.
• D. HBOT decreases tissue oxygenation.

Answer: (A)

Hyperbaric oxygen therapy works by delivering very high oxygen levels that cause vasoconstriction in normal, non-ischemic tissues. This vasoconstriction lowers capillary hydrostatic pressure, which reduces fluid leakage from capillaries and thus edema. At the same time, the elevated inspired oxygen dramatically increases the amount of oxygen dissolved in plasma and the overall oxygen content of the blood, so tissue oxygen delivery remains excellent or even improves despite reduced blood flow from constriction. This combination—less edema from reduced fluid leakage and preserved oxygen delivery from high PaO2—explains why HBOT helps reduce edema without compromising oxygen supply. The other ideas don’t fit: increasing capillary hydrostatic pressure would worsen edema, diuresis isn’t the primary mechanism for edema reduction here, and tissue oxygenation is not decreased (it is enhanced).