Posted by H on January 28, 2003 at 09:19:28:
In Reply to: I thought LaJolla had some deep water down there? posted by Karl S. on January 27, 2003 at 20:47:00:
Karl, I have never heard of anyone purging CO2 before doing a scuba dive. Interesting. Now, since our body is triggered to breathe based on CO2 concentration and not O2, wouldn't the blow down only be valid for the first breath? Freedivers only take one breath so it is a valid practice. But unless you practive the bonzai descent, your CO2 concentration will return to normal before you even hit 20 feet, less if you stop to do a proper bubble check and S drill.
Is there some physiological systemic response that I do not know about that is keeping CO2 concentration down during descent? I thought the main way to reduce CO2 concentration was to avoid skip breathing, reduce work at depth, and dive proper helium based mixes.
http://www.mtsinai.org/pulmonary/books/scuba/gaspress.htm