Fragility of red blood cells under 31 atmosphere absolute for 14 days

The present investigation was undertaken during the course of a 14-day dry saturation dive at 31 ATA to study hematologic changes and osmotic fragility of red blood cells in relation to lipid contents of the plasma and red cells. Increase in the hematocrit and blood cell count was observed in the early phase at 31 ATA, which was attributed to the hemoconcentration caused by the hyperbaric diuresis. Osmotic fragility of red blood cells fluctuated during the course of the experiment, but the change was not related to the atmospheric pressure. Cholesterol and phospholipid contents in red blood cells and the plasma also fluctuated but the change was not caused by the pressure. However, an overall correlation between the osmotic fragility and the phosphatidyl choline of red cells and the correlation between the osmotic fragility and the total cholesterol level in the plasma were observed at both 1 and 31 ATA. These correlations revealed an intimate relation between the red cell fragility and lipid composition of the cell membrane and the plasma within intra- and interindividual variations during the course of the dive. The present result did not indicate any significant alteration of red blood cell function due to prolonged exposure to 31 ATA He-O2 environment.