Risk of neurological decompression sickness in the diver with a right-to-left shunt: literature review and meta-analysis.

OBJECTIVE

Literature review and meta-analysis to review the evidence of relationship between the presence of right-to-left shunts (RLSs) and the occurrence of neurological decompression sickness (DCS) in divers.

DATA SOURCES

MEDLINE, Google Scholar, and Health Technology Assessment databases.

STUDY SELECTION

Five case-control studies in which the prevalence of a RLS in a group of divers with neurological DCS was compared with that of a group of divers with no history of DCS, 3 cross-transversal studies in which the prevalence of RLS was measured in divers with neurological DCS, and 4 cross-transversal studies in which the prevalence of RLS was measured in divers with no history of DCS were reviewed.

DATA EXTRACTION

Only case-control studies were retained for meta-analysis.

DATA SYNTHESIS

This meta-analysis gathers 5 studies and 654 divers. The combined odds ratio of neurological DCS in divers with RLS was 4.23 (3.05-5.87). The meta-analysis including only large RLS found a combined odds ratio of 6.49 (4.34-9.71).

CONCLUSIONS

Because of a low incidence of neurological DCS, increase in absolute risk of neurological DCS due to RLS is probably small. Thus, in recreational diving, the systematic screening of RLS seems unnecessary. In professional divers, because of a chronic exposition and unknown consequences of cerebral asymptomatic lesions, these results raise again the benefit of the transcranial Doppler in the screening and quantification of the RLS, independently of their location.