Hematologic and hemostatic changes with repetitive air diving

In order to determine the effects of repetitive compression-decompression cycles on hematologic and hemostatic factors in humans, 14 subjects were exposed to 150 ft sea water gauge (fswg) for 30 min with standard U.S. Navy decompression on each of 12 consecutive days. Red blood cell number, volume, and size distribution; hemoglobin concentration; hematocrit; white blood cell number and differential counts; platelet number and volume; prothrombin and partial thromboplastin times; and fibrinogen and fibrin/fibrinogen degradation products were measured in venous blood samples collected before the first and after alternate dives. Subjects in the study had no symptoms other than pruritus and occasional fatigue following the exposures. More than 60% had venous gas emboli detectable by precordial doppler monitoring which generally persisted for 3-5 h after surfacing. Results show a small decrease in red cell mass, with an increase in size distribution and no change in mean corpuscular volume. No change in total white cell number was noted, but the basophilic granulocytes and atypical lymphocytes were elevated at the end of the series. A biphasic change was noted in monocyte number, and immature neutrophilic granulocytes were reduced. No change in platelet number or volume, or in the prothrombin/partial thromboplastine time, was apparent. Although fibrinogen concentration significantly decreased during the exposures, fibrin/fibrinogen degradation products remained undetectable. All changes remained in a clinically acceptable range.(ABSTRACT TRUNCATED AT 250 WORDS)