Freediving after Breathing on Scuba?

[rmediver2002]

Let me see if I understand this correctly, the risk mainly lies in the exercise (Due to increased Heart Rate?) and not as was stated before. by Genisis: "Bubbles compress and PASS the lungs" therefore ending up on the arterial side instead of the veinous?

Exercise is an additional risk factor while nitrogen is still in solution in the divers tissues... The agitation of strenuous or rapid activity is causing the same effect within the body as shaking up a soda bottle. It increases the amount of gas coming out of solution.

The statement Genesis is completely accurate and is an entirely different risk to consider...

Jeff Lane

 

[ScubaSky]

Extreme Valet Diving for me!

 

[Frank O]

ScubaSky once bubbled...
Let me see if I understand this correctly, the risk mainly lies in the exercise (Due to increased Heart Rate?) and not as was stated before. ... I guess swimming / snorkeling isn't a good idea in that case also, Let alone the freediving.

Well, I don't think it completely boils down to that. I get the message about avoiding post-scuba-dive exertion. Unless you are dealing with special factors (facing a current; spearo fighting a fish; etc), however, freediving in many cases can be very gentle and tranquil, and in my experience would rate quite low on the MET (metabolic equivalent) scale. (Freedivers in fact typically focus on decreasing their exertion and getting into a meditative state of mind so as to extend their breath-hold.) I was given to understand that the primary danger of freediving after scuba wasn't the exertion per se, but rather the fact that you are making quick descents and ascents that complicate your deco from scuba with yo-yo'ing pressure changes. No?

 

[Charlie99]

ScubaSky, WKPP article is another explanation of the problem that Genesis was describing ---- venous gas emboli getting transferred over to the arterial side where they can do a lot of damage.

 

[rmediver2002]

I was given to understand that the primary danger of freediving after scuba wasn't the exertion per se, but rather the fact that you are making quick descents and ascents that complicate your deco from scuba with yo-yo'ing pressure changes. No?

That is correct...

 

[ColdH2Odvr]

What about the Valsalva strain (venous preload) of the initial dive exacerbating a PFO? Also, it seems that at least the initial dive is fairly strenuous requiring both back and leg muscles (source of micro bubbles).

 

[holdingmybreath]

ColdH20Dvr, the valsalva does involve strain so most freedivers do the Frenzel, which is far more efficient. The initial start of the dive should be a good surface dive which would take you quickly and almost effortlessly to 15 feet or so, and therefore not require any great deal more of a workout than the next 25 or so feet to nuetral/negative bouyancy. If a freediver is doing things correctly, a good freedive will be paced, relaxed, methodical, and not strained. The bouncing from surface to depth to surface would be the main cause of DCS while freediving following scubadiving.

 

[Dr Deco]

Dear SCUBA SOURCE Readers:

DCS and Free Diving

I believe that the jury is still out on this one. My original thoughts were that arterialization would not occur with repressurization. This was based on observation by me and other researchers with animals (all quadrupeds); bubbles were never found to pass from the venous to the arterial side with recompression.

However, the change in blood volume in the right atrium (preload) with position in the water and combined with some Valsalva-like maneuvers might change the picture in humans (all bipeds).

In the last couple of years, largely in response to comments on SCUBA BOARD, I am beginning to rethink this position. Arterialization might be a bigger player than I first thought.

Dr Deco :doctor: