Abstract
Acclimatization (an adaptive change in response to repeated environmental exposure)
to diving could reduce decompression stress. A decrease in post-dive circulating venous
gas emboli (VGE or bubbles) would represent positive acclimatization. The purpose
of this study was to determine whether four days of daily diving alter post-dive bubble
grades. 16 male divers performed identical no-decompression air dives on 4 consecutive
days to 18 meters of sea water for 47 min bottom times. VGE monitoring was performed
with transthoracic echocardiography every 20 min for 120 min post-dive. Completion
of identical daily dives resulted in progressively decreasing odds (or logit risk)
of having relatively higher grade bubbles on consecutive days. The odds on Day 4 were
half that of Day 1 (OR 0.50, 95% CI: 0.34, 0.73). The odds ratio for a >III bubble
grade on Day 4 was 0.37 (95% CI: 0.20, 0.70) when compared to Day 1. The current study
indicates that repetitive daily diving may reduce bubble formation, representing a
positive (protective) acclimatization to diving. Further work is required to evaluate
the impact of additional days of diving and multiple dive days and to determine if
the effect is sufficient to alter the absolute risk of decompression sickness.
Key words
acclimatization - air diving - decompression sickness - echocardiography - repetitive
- venous gas emboli
