Subaqua Sternal Rubs

I am just reviewing for my physiology midterm, when I came across the concept of Shallow-Water Blackout.

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Normally, accumulation of Carbon Dioxide (CO2) is the major stimulation to take a breath, not lack of Oxygen (O2). Some free-divers/snorkelers take many deep, quick breaths before descending because they think that this will increase there O2 content in their blood, and allow them to stay down longer. This is WRONG. In the normal individual, the blood's oxygen carrying molecule, Hemoglobin, is already 97-98% saturated, so hyperventilating will not result in any marked increase in O2 content. What is does do, however, is remove more CO2 than normal, down to a level where there is not enough CO2 to reach the "Desire to Breathe" red line in the graph. This results in passing out and/or death, as the primary drive to breathe is knocked out. This is an overly simplified model; for more detailed information, read this nice article.

So the most important rule in diving? Well, according to one of the PADI Dive Instructors here, it's "Have Fun," but personally, I'd rather go with "Never hold your breath, and always breathe at a normal, relaxed rate."

Can you tell I can't wait to go diving again this weekend, after 3 weeks off?

Blood-sucking Lawyer Clause: This article is for general information use only. I make no warranty as to the factual accuracy of the information presented in this article or any articles linked to; and I assume no liability if you choose to use this information - Use at your own risk. Consult a qualified health care professional for any medical advice you may require.

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