[abstract] THE INCIDENCE OF VENOUS GAS EMBOLI IN RECREATIONAL DIVING.

Abstract

BACKGROUND: The purpose of this paper is to re-analyze data presented previously (1) to assess the level of detectable Doppler bubbling in recreational divers. METHODS: From 1989-91, the Divers Alert Network monitored recreational divers for Doppler-detected venous gas emboli (VGE) and depth-time profiles following multi-day, repetitive, multi-level exposures. RESULTS: A Spencer score > 0 occurred in 61 of 67 subjects (91%) and 205 of 281 dives (73%). No subject developed decompression sickness (DCS) although 102 dives (36.3%) scored at Spencer Grades 2 or 3 (High Bubble Grade, HBG). HBG incidence increased with maximum dive depth (p=0.01) and repetitive diving (p=0.002) while decreasing with multi-day diving (p<0.01). Dive time failed to achieve significance in the analysis, most likely due to the multi-level nature of the profiles. HBG incidence rose approximately 25% over a depth range of 50-110 fsw for both first dives and repetitive dives although HBG incidence for repetitive dives was approximately 20% more common. HBG decreased approximately 25% over the 6-8 days of diving suggesting a phenomenon similar to DCS adaptation. HBG incidence for males was approximately 20% greater than for females (p=0.013) and increased by 20-30% over a 30-50 year age range (p<0.01). A model computing DCS risk was equally parsimonious with repetitive diving and maximum depth in predicting HGB. CONCLUSION: We conclude that Doppler bubbles are common in recreational divers and further that the incidence of HGB increases with repetitive diving, gender, age, maximum depth and decreases with multi-day diving. 1. DCS risk and Doppler bubbles in sport divers. Dunford R, Wachholz C, Huggins K, Vann R, Gerth Wand Bennett P. Undersea Biomed. Res. 1993; 20(Suppl):127.