apnea and the bends

[buff]

I read that Sperm whales have a large trachea, and this allows air to move from their lungs and into the trachea during deep dives. This prevents getting the bends. So is it possible to get the bends, even during breath holding, if you dive as deep as whales do?

Can one of our good doctors describe the effect of deep diving, breath holding and the bends?

And while your at it could you also answer why record setting breath holders sometimes black out just near the surface during their deep water attempts.

thanks
Mike

 

[wazza]

I am not a Doctor but u can learn this from a diving book.

To tell u the truth I never heard about some one who was free diving and had the bends but this is what u need to know all about Shallow water black out.

Free divers Hyperventilate at the surface to extend their breath hold time. For a human to remain conscious there has to be a certain concentration of oxygen in the blood.
The changes in the partial pressures of oxygen and carbon dioxide in the arterial blood on a free dive to 10 M and subsequent return to the surface
At the surface the arterial tension of CO2 is 44mmhg and O2 at 100mmhg. These are normal values for a healthy human at sea level. After hyperventilating the carbon dioxide is decreased to half its normal value 20 mmhg and partial pressure of oxygen 120 mmhg increase slightly.
The carbon dioxide level that stimulates one to breath . at 10m oxygen has been used up and there had been little or no real increase in CO2. however due to the increased in ambient pressure to 2 ata the actual partial pressure of the carbon dioxide has doubled to 40 mmhg. Oxygen though consumed to the equivalent of 80 mmhg at sea level is 150 mmhg at 10m so there is no Oxygen deprivation distress at depth.
Eventually the carbon dioxide rises slightly to 44 mmhg a level sufficient to simulate the diver to want to breath or in this case return to the surface.
While at 10 m the partial pressure of the oxygen 80 mmhg is sufficient to maintain consciousness. How ever a significant amount of oxygen has been utilized .
When the diver returns to the surface the partial pressures of the gases are cut in half by the reduction in the ambient pressure to 1 ata the net effect is the reduction in ambient pressure falls to 49mmgh or below the level necessary to remain conscious and the diver blacks out.

Last year I had the chance to be helping with the world record yasmine the Turkish girl that did 105 m on one breath and we did learn a lot form what she did. Plus we did a course with her and her instructor how to save a free diver who is unconscious if he was in the water or at the surface and how to give him air in the water if he asked for it. Believe me we thought that this is very easy cos all of us were tek instructors but it wasn’t.

I will try to post a picture for that event

by the way :
The bends could happen if u r free diving between dives …..!!!!!!!!!!!!!!!!

 

[scubadoc]

There is a nice article about whales and DCS by Dr. Fred Bove at http://www.scubamed.com/feature.htm#anchor513871 .

Shallow water blackout can be studied at http://www.scuba-doc.com/latenthypoxia.html .

Taravana is a form of DCS that develops in native free divers. Read more at http://www.scuba-doc.com/taravana.html .

Best regards and good things!!

scubadoc
http://scuba-doc.com/

 

[buff]

"The blood is likely to be protected by the collapse of the lungs during descent, with a reduction of the capacity to transfer gases from lung to blood. Under these circumstances, there is not enough nitrogen to be distributed to blood and tissues, and the supersaturation needed to cause bubble formation is prevented."



........So whales-at least Sperm whales -exhale before diving to prevent a nitorgen pressure gradient between lung and blood. Sperm whales must have a massive amount of myoglobin in their muscles to keep a high enough O2 tension when diving as long as they do. I ber they have the hightest myoblobin concentration of any animal.