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>>Chris, >>I've often wondered why some of us seem to be able to violate the tables >>(not intentionally), dive frequently and deep and never get bent, while >>others get bent well within the tables etc. If 27% of the population and >>diving population have a PFO then perhaps we really need two sets of tables >>-- one for those with this defect and one for those without? >> >>I'd also like to know how a PFO causes a problem on the aterial side when >>the normally fluid dynamics would seem to make this a remote possibility. >>Can you educate all of us? > >Normally the PFO will not cause a problem. However, the pressure in the >venous side of the circulation can rise, for example when performing a >Valsalva manoeuvre or when bending double forcibly e.g. when getting into >a RIB. When you cough, you also raise the intrathoracic pressure and then >a small amount of blood from the venous side can get through to the arterial >side, carrying any bubbles with it. Sometimes the PFO can only be demon- >strated with difficulty on contrast echocardiography and then it is less >likely that such problems will occur. > >I do not think that two sets of tables are called for. How are you going >to find out if you have a PFO? Will the knowledge make any difference to >your diving? The test is expensive and must be performed by an expert who >has carried out these tests many times and knows what to look for. Even >cardiology consultants may not be able to do this. > >Chris. >*************************************************************** >* Dr. Chris. Edge * Tel. +44-865-275-338 * >* Glycobiology Institute * Fax. +44-865-275-216 * >* Oxford University * e-mail chris@gl*.ox*.ac*.uk* * >* South Parks Road * 100117.3646@co*.co* * >* Oxford OX1 3QU U.K. * * >*************************************************************** Chris, I thought that a good doppler study of the heart should pick up a PFO? Not that expensive if extra precautions are in order for someone who has the defect. Harold Gartner 6900 Via Alba Camarillo, California 93012 home: (805) 482-9743 office: (213) 487-6240 CompuServe ID# 71470,1423 Internet: hgartner@ra*.or*
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