Hematologic and hemostatic changes with repetitive air diving.

Area of Science:

• Physiology
• Hematology
• Diving Medicine

Background:

• Repetitive compression-decompression (C-D) cycles are inherent to diving activities.
• Understanding the physiological impact of repeated C-D exposures on human blood factors is crucial for diver safety.

Purpose of the Study:

• To investigate the effects of 12 consecutive days of simulated diving (150 fswg for 30 min) on hematologic and hemostatic parameters in human subjects.
• To assess the incidence and persistence of venous gas emboli (VGE) following these exposures.

Main Methods:

• 14 subjects underwent daily 30-minute exposures at 150 fswg for 12 days with standard US Navy decompression.
• Hematologic parameters (RBC, WBC, platelets) and hemostatic factors (PT, PTT, fibrinogen, FDP) were analyzed from venous blood samples.
• Precordial Doppler monitoring was used to detect venous gas emboli.

Main Results:

• A slight decrease in red blood cell mass and altered red blood cell size distribution were observed.
• Elevated basophilic granulocytes and atypical lymphocytes, with a biphasic change in monocytes, were noted.
• Fibrinogen concentration decreased significantly, but fibrin/fibrinogen degradation products remained undetectable; no changes in platelet counts or coagulation times were apparent.
• Over 60% of subjects exhibited detectable venous gas emboli, persisting for 3-5 hours post-dive.

Conclusions:

• Repetitive diving exposures induced minor, clinically acceptable hematologic shifts.
• The hemostatic system showed resilience, with no significant alterations in coagulation.
• The presence of venous gas emboli, despite the absence of overt symptoms, highlights the need for continued monitoring in repetitive diving scenarios.