Risk of decompression illness among 230 divers in relation to the presence and size of patent foramen ovale

Abstract

Background The risk of developing decompression illness (DCI) in divers with a patent foramen ovale (PFO) has not been directly determined so far; neither has it been assessed in relation to the PFO's size. Methods In 230 scuba divers (age 39±8 years), contrast trans-oesophageal echocardiography (TEE) was performed for the detection and size grading (0-3) of PFO. Prior to TEE, the study individuals answered a detailed questionnaire about their health status and about their diving habits and accidents. For inclusion into the study, ≥200 dives and strict adherence to decompression tables were required. Results Sixty-three divers (27%) had a PFO. Overall, the absolute risk of suffering a DCI event was 2.5 per 104 dives. There were 18 divers (29%) with, and 10 divers (6%) without, PFO who had experienced ≥1 major DCI events (P=0.016). In the group with PFO, the incidence per 104 dives of a major DCI, a DCI lasting longer than 24 h and of being treated in a decompression chamber amounted to 5.1 (median 0, interquartile range [IQR] 0-10.0), 1.9 (median 0, IQR 0-4.0) and 3.6 (median 0, IQR 0-9.8), respectively and was 4.8-12.9-fold higher than in the group without PFO (P<0.001). The risk of suffering a major DCI, of a DCI lasting longer than 24 h and of being treated by recompression increased with rising PFO size. Conclusion The presence of a PFO is related to a low absolute risk of suffering five major DCI events per 104 dives, the odds of which is five times as high as in divers without PFO. The risk of suffering a major DCI parallels PFO size. © 2004 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.