Echocardiographic evaluation of intracardiac venous gas emboli following in-water recompression.

Decompression sickness is a potentially fatal illness. Optimal treatment is dry recompression with hyperbaric oxygen. In-water recompression (IWR) offers expedited treatment but has insufficient evidence to recommend it as a treatment option. This trial compares IWR to standard surface oxygen treatment using 2D echocardiography as the semi-quantitative measurement for inert gas loading. Divers were randomly assigned to either IWR or normobaric oxygen (NBO2). A provocative dive profile to 33.5 meters for 25 minutes was used to stimulate bubble formation. After 60 minutes on the surface, bubble scoring was obtained using 2D echocardiography. Divers underwent either the IWR or NBO2 treatment for 82 minutes. Echocardiography was then repeated. Pre-treatment mean bubble counts were 28.1 bpf (bubbles per echo frame), [+/- 13.2 to 43.0 95% CI] for IWR, and 18.3 bpf [+/- 0.0 to 39.6 95% CI] for NBO2. After treatment, mean bubble score dropped to 0.1 bpf [+/- 0.0 to 0.2 95% CI] (p < 0.01) and 1.8 bpf [0.0 to 3.8 95% CI] (p = 0.103) respectively. IWR vs. NBO2 reduction of bubble counts was 99.7% vs. 90.1%; however, this was not found to be statistically significant. IWR reduced the central VGE load compared to NBO2, suggesting that IWR is a viable emergency treatment when a recompression chamber is unavailable.