Abstract

Objective: paradoxical gas embolism through right-to-left (R/L) shunts is considered as a potential cause of certain types of decompression sickness. This study was done to assess whether 4 months of repetitive diving and strenuous exercises lead to an increased prevalence of R/L shunting in a group of military divers. Methods: using a standardized contrast-enhanced transcranial Doppler technique, 17 divers were re-examined for the presence of a R/L shunt 4 months after their initial examinations. R/L shunts were classified as type I if observed only after a straining maneuver and type II if present at rest. Results: initial prevalence of R/L shunt was 41%: 6 types I and 1 type II . At the second examination, prevalence was 47% with the appearance of one type I shunt that was not previously present. We found no significant increase in the prevalence and size of R/L shunt. Conclusion: it is speculated that diving-related phenomena, such as variations in right atrial pressures during the end stages of or events immediately after a dive could generate a R/L shunting. However extreme conditions of repetitive diving and strenuous exercises are not able to cause a permanent modification of R/L permeability over a period of 4 months.