Body Fat & Off Gasing

[MN Lakeman]

I have been diving for 3 years, & my dive buddies give me a hard time about the fact that I have to dive with 3mm of neoprene more than they do - whether in the Carribean or Lake Superior. Well I laugh it off, because I know that due to being a masters swimmer for 25 years, swimming 6 to 8 miles a week, its because of having 6% body fat that I chill easily. Here's my question: Though I have to deal with watching the chill factor while diving, don't I have the advantage over my "chunky" dive buddies of gassing off nitrogen faster than they do? I thought I had read in my PADI manual somewhere that the fatty tissues do most of the gas absorption. Its not that I am inclined to push my NDL's - as I am a very conservative diver, but love the deep.

 

[Dr Deco]

Hi MN lakeman:

Body Fat
While it is true that adipose (fat) tissue dissolves considerably more nitrogen (or helium) than "aqueous" tissue (e.g., muscle, tendon, ligament), fat tissue does not appear to play a large role in joint pain decompression sickness ("the bends"). Assuming that joint pain arises in tendons and ligaments (unproven, but certainly a good possibility), there is not really much fat in these tissues.

In those areas of the body where there is considerable fat (e.g., the abdomen in men), pain does not appear during decompression. This is probably most fortunate.

The real problem with fat is that it dissolves considerable volumes of nitrogen, produces decompression bubbles, and dumps these into the venous system. When these bubbles enter the vena cava, they are carried to the heart. If a large number (volume) are present, they can lead to cardiopulmonary problems such as reduced cardiac output, “chokes” and arterialization [where the bubbles can now travel to the heart, brain and spinal cord].

Final Result :11:

The problem is then with a diver who is obese and finds that a rapid ascent without adequate decompression has occurred. This diver could well find that the decompression goes much more poorly than in a thin diver. While this does not occur often with humans, the observation of cardiopulmonary collapse is very common when laboratory animals are concerned.

Dr Deco :doctor:

 

[MN Lakeman]

Fantastic explaination - thanks.

 

[Saturation]

Final Result :11:

The problem is then with a diver who is obese and finds that a rapid ascent without adequate decompression has occurred. This diver could well find that the decompression goes much more poorly than in a thin diver. While this does not occur often with humans, the observation of cardiopulmonary collapse is very common when laboratory animals are concerned.

Dr Deco :doctor:

Hi Dr. D:

In experimental animals during massive offgassing, were animals given surface 100% 02 [1 ATA] see the effect on their cardiopulmonary systems?

 

[Dr Deco]

Hi Dr. D:

In experimental animals during massive offgassing, were animals given surface 100% 02 [1 ATA] see the effect on their cardiopulmonary systems?

Usually they were not give oxygen. This would be of value in helping to reduce the gas bubble load to the heart and lungs.

Dr D

 

[Saturation]

Usually they were not give oxygen. This would be of value in helping to reduce the gas bubble load to the heart and lungs.
Dr D

Hi Dr. D:

Thanks for the speedy reply. Any guestimate or estimate on how quickly pulmonary artery bubbles resolve once the subject breathes 100% 02?

 

[Dr Deco]

The attached graph shows bubble washout from the pulmonary artery. It is from Brubakk, UHM, 31 (1), 73-79, 2004.

{The reply just above this was withdrawn as I labeled the lines incorrectly. MRP}

 

[Saturation]

The attached graph shows bubble washout from the pulmonary artery. It is from Brubakk, UHM, 31 (1), 73-79, 2004.

{The reply just above this was withdrawn as I labeled the lines incorrectly. MRP}

Hi Dr. D:

Tha'ts wonderful, and mea culpa for not seeing in the the journal ... on pulling it noted its ear marked for reading! Did read it through.

What is amazing and correlates a clinical response to animal experimental evidence, is how rapidly the bubble resolve with 100% 02 1 ATA [ 02 100kPa as per Brubbak]. Bubble volume may not be reduced substantially initially to incur a clinical response.

Its striking when in the field: two folks I dove with this year eventually collapsed within 3 hours post dive in decompression dives. Increasing vague discomfort across their chests gradually developed over those 3 hours but were ignored, one developed an unexplained dry cough [ chokes] ... by the time I intervened their pulses were barely palpable, and they were clinically hypotensive. No joint pain, rash, no neurologic findings. Subjective well being scored 1/10 ... afte 1-2min of 02 100kPa, pulses were strong and palpable, by 10min, well being scores were 9/10. After 30min, they were 10/10. Neither folks were chambered. Fluids were ingested, but well being and pulse improved before substantially fluids were administered.

While no definitive evidence exists that bubbles were indeed in the pulmonary tree these responses are so similar to resolving emboli in the pulmonary tree ... in regular folks a thrombotic emboli is near fatal until removed ... in gas emboli steps can be taken to extract gas either via a central line or other means with immediate response of BP. In diving, the use of 02 to collapse the inert gas concentration around the bubble and hence collapse the bubble seems to be operant in these folks.

 

[Dr Deco]

Hi Saturation:

Wonderful stories with good endings!

Dr Deco :doctor: