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, P200 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 10 4 dives. There were 18 divers (29%) with, and 10 divers (6%) without, PFO who had experienced P1 major DCI events ðP ¼ 0:016Þ. In the group with PFO, the incidence per 10 4 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 ðP < 0:001Þ. 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 10 4 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.

Patent Foramen Ovale: Current Pathology, Pathophysiology, and Clinical Status

“…A recent study found a strong relationship between PFO size and DCS in a study of 230 divers (6). Another study demonstrated the functional and anatomic characteristics of PFO with and without DCS (7).…”

“…It is a risk factor for several serious clinical syndromes, including paradoxic systemic embolism, such as ischemic stroke (3), myocardial infarction (4), decompression sickness (DCS) in divers (5)(6)(7), and complications of pulmonary embolism (8). Recent evidence further implicates PFO as a possible cause of migraine headache through mechanisms not yet understood.…”

Patent foramen ovale: A new disease?

“…In this case, the diver must be strongly advised of the risk in continuing scuba practice, regardless of the presence of a previous DS event, and he/she should consider percutaneous transcatheter closure of the PFO to allow safer scuba activity. On another hand, the finding by Torti et al [68] that a small PFO behaves like no PFO regarding the frequency of serious DS renders the recommendation, in this case, less strict for refraining from diving.…”

The significance of patent foramen ovale

“…However, PFO has been found to be implicated; e.g., in cryptogenic stroke [16], decompression illness [17], and perhaps migraine with aura [18].…”

“…PFO has been found to increase the risk of major decompression illness five times from one to five in 10,000 dives and the risk increases with increasing PFO size [17]. The current European clinical fitness to diving practice does not, however, include PFO screening before diving, as the absolute risk is very low and most patients recover completely after recompression treatment [60].…”