Decrease in platelet count during saturation diving

Background: The change in platelet count (PC) occurring during saturation d iving has rarely been discussed. We set out to clarify the details of this change in PC, and its relationship with: i) the storage depth and duration of the saturation dive, and ii) the presence of decompression bubbles. Meth ods: In a total of 42 divers, the change in PC was measured in 8 simulated saturation dives (1992-1998) using a Deep Diving Simulator with decompressi on procedures based on the modified DUKE-GKSS schedule. Blood samples were taken before the dive, at the bottom (twice), during decompression, on surf acing, and about 1 wk after surfacing. Decompression bubbles were examined by ultrasonic M-mode echocardiography. Results: PC (mean +/- SD x 10(4.)mul (-1)) was 23.9 +/- 4.85, 24.9 +/- 4.9, 24.2 +/- 4.8, 19.2 +/- 4.41, 20.1 +/ - 4.5*, 25.0 +/- 5.1 on the occasions listed above (*= p ( 0.05 vs. pre-div e). The PC showed no correlation with either storage depth or dive duration . Decompression bubbles were detected during decompression in only 2 divers (4.8%), and the bubbles disappeared immediately after surfacing. In these 2 divers the decreases in PC values from baseline to the middle of decompre ssion and on surfacing were 2 and 2.7 x 10(4.)mul(-1), and 3.4 and 1.7 x 10 (4.)mul(-1) respectively. No diver complained of decompression sickness. Co nclusion: The magnitude of the decrease in PC (< 5 x 10(4.)mul(-1)) and the time to recover to the pre-dive value (< 1 wk) suggests that changes in PC during saturation diving should not cause any clinical problems. The mecha nisms underlying the decrease in PC remain unclear.