Increased red cell osmotic fragility and hematocrit after hyperbaric O2 exposure are related to acidosis.

Exposure to hyperbaric O 2 (0.6 MPa) until convulsion occurred resulted in increased red blood cell osmotic fragility, increased hematocrit, and acidosis. Correction of the mixed metabolic and respiratory acidosis in arterial blood samples completely restored osmotic fragility and lowered hematocrit by 20%. Rats exposed to intermiHent hyperbaric O 2 (repeated cycles of 7 minutes of O 2 and 7 minutes of air) tolerated significantly more O 2 time than those exposed continuously. Intermittently exposed animals had smaller increases in osmotic fragility and less-severe acidosis. We verified the influence of pH on osmotic fragility and hematocrit in rats made acutely acidotic and corrected in vivo