Patent foramen ovale predicts decompression sickness in casual divers

High-grade patent foramen ovale (PFO) is a strong risk factor for unprovoked decompression sickness (DCS) among recreational scuba divers, a recent study has found.

Using transcranial color-coded Doppler sonography, researchers screened 489 consecutive divers (mean age, 35.6±9.0 years; 86.5 percent male) for PFO. DCS history at baseline was collected from all participants at the time of screening. Unprovoked DCS was defined as symptoms occurring <24 hours after a dive that was compliant with all safety rules and guidelines. Those that developed with the background of severe exhaustion or inadequate hydration were considered provoked DCS.

Forty percent of the divers were positive for a PFO, while 7 percent suffered from an unprovoked DCS. There was a total of 54 unprovoked DCS episodes reported across a total of 169,411 dives. The occurrence rate per dive was 0.03 percent.

Almost all the divers with a history of unprovoked DCS had a PFO (97 percent), as opposed to only 36 percent in the no-episode controls (p<0.001). This was also true for grade 3 PFOs (86 percent vs 18 percent; p<0.001).

Cox proportional hazards analysis found that PFO was a significant risk factor for unprovoked DCS (adjusted hazard ratio [HR], 60.0, 95 percent CI, 8.2–438.5; p<0.001), as was grade 3 PFO (adjusted HR, 93.0, 12.5–688.7; p<0.001). Low-grade DCS likewise emerged as a nominal risk factor, but was only of borderline significance (adjusted HR, 10.8, 1.0–121.8; p=0.054).