Most research and expert opinion suggest that if a recreational diver has no history of DCS, diagnosed or suspected, and is otherwise asymptomatic for this abnormality screening does not appear warranted.
1. Clin J Sport Med. 2009 May;19(3):231-5.
Risk of neurological decompression sickness in the diver with a right-to-left shunt: literature review and meta-analysis.
Lairez O, Cournot M, Minville V, Roncalli J, Austruy J, Elbaz M, Galinier M, Carrie D.
Department of Cardiology, CHU Rangueil, Toulouse, France. firstname.lastname@example.org
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.
2. "Undersea Hyperb Med. 1998 Fall;25(3):175-8.
Risk of decompression sickness with patent foramen ovale.
Cardiology Section, Temple University Medical School, Philadelphia, Pennsylvania, USA.
Comment in: Undersea Hyperb Med. 1999 Spring;26(1):49-50.
Several reports have described populations of divers with decompression sickness (DCS) who have a patent foramen ovale (PFO). The presence of a PFO is known to occur in about 30% of the normal population, hence 30% of divers are likely to have a PFO. Although observations have been made on the presence of a PFO in divers with and without DCS, the risk of developing DCS when a diver has a PFO has not been determined. In this study, Logistic Regression and Bayes' theorem were used to calculate the risk of DCS from data of three studies that reported on echocardiographic analysis of PFO in a diving population, some of whom developed DCS. Overall incidence of DCS was obtained from the sport diving population, from the U.S. Navy diving population, and from a commercial population. The analysis indicates that the presence of a PFO produces a 2.5 time increase in the odds ratio for developing serious (type II) DCS in all three types of divers. Since the incidence of type II DCS in these three populations averages 2.28/10,000 dives, the risk of developing DCS in the presence of a PFO remains small, and does not warrant routine screening by echocardiography of sport, military, or commercial divers."
3. "Cardiovascular Fitness and Diving
Patent Foramen Ovale
At present, most diving physicians agree that the risk of a problem associated with a PFO is not significant enough to warrant widespread screening of all divers. An episode of severe decompression illness that is not explained by the dive profile should initiate an evaluation for the existence of a PFO."
4. "SWISS MED WKLY 2001;131:365–374
Recreational scuba diving, patent foramen ovale and their associated risks
Markus Schwerzmann, Christian Seiler
Cardiology, Swiss Cardiovascular Center Bern, University Hospital, Inselspital, Bern, Switzerland
"Contrast transoesophageal echocardiography is not mandatory in the routine medical evaluation of asymptomatic sport divers", nor in asymptomatic commercial or professional divers for the primary prevention of decompression illness events."
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