Minimizing DCS damage

[Outrager]

I have posted this question in Tech forum earlier, but it really belongs here:

Given any multi-level deco schedule and insufficient gas to complete all required stops, is there a common algorythm of minimizing the damage or will it depend on a particular mix/profile situation?

An argument i recently had revolved around 2 choices: either complete deeper stops and skip the shallow ones, or shorten all stops proportionally. The first choice seems intuitively better, as we offgas faster tissues that would probably do more rapid damage, and it gives a choice of immediate recompression, if there's more gas available on the surface. Howerev, i would love to hear a more scientific opinion.

Please do not hijack this thread by saying anything about proper gas planning

bsbd!

Yuri

 

[Dr Deco]

Hello Outrager:

I might hazard an initial guess that proportional reduction of all stops would be best coupled with constant moving of the arms and bicycle movements of the legs during the stops. This activity would increase gas usage, but would considerably increase the off gassing of nitrogen.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[Scuba]

constant moving of the arms and bicycle movements of the legs during the stops. This activity would increase gas usage, but would considerably increase the off gassing of nitrogen.

Dr Deco, have you, or anyone else, been able to quantify the difference, in general or specific terms? For example: 10 min. static stop can be reduced by X min. using the leisurely exercise you recommend?

Also, is there any research to suggest whether this type of exercise during stops has any significant impact on divers breathing oxygen rich mixtures, 100% O, or gas mixtures with helium, in regards to DCS or toxicity risk.

 

[Dr Deco]

Hello scuba:

We have been able to quantify the exercise effects but the algorithm exists only for decompression to altitude. This is what is used in NASA operations. Nothing exists for diving at the current time.

Exercise will work for gases other than nitrogen and will work during pure oxygen breathing. The latter is utilized for prebreathe prior to EVA.

Some references appear below.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm


References :book3:

Dujic Z, Obad A, Palada I, Ivancev V, Valic Z.
Venous bubble count declines during strenuous exercise after an open sea dive
to 30 m.Aviat Space Environ Med. 2006 Jun;77(6):592-6.

Dujic Z, Palada I, Obad A, Duplancic D, Bakovic D, Valic Z.
Exercise during a 3-min decompression stop reduces postdive venous gas bubbles.Med Sci Sports Exerc. 2005 Aug;37(8):1319-23.

Blatteau JE, Gempp E, Galland FM, Pontier JM, Sainty JM, Robinet C.
Aerobic exercise 2 hours before a dive to 30 msw decreases bubble formation
after decompression.Aviat Space Environ Med. 2005 Jul;76(7):666-9.

Webb JT, Pilmanis AA, Balldin UI. Altitude decompression sickness at 7620 m following prebreathe enhanced with exercise periods. Aviat Space Environ Med. 2004 Oct;75(10):859-64.

Jankowski LW, Tikuisis P, Nishi RY. Exercise effects during diving and decompression on postdive venous gas emboli. Aviat Space Environ Med. 2004 Jun;75(6):489-95.

Webb JT, Pilmanis AA, Fischer MD, Kannan N. Enhancement of preoxygenation for decompression sickness protection: effect of exercise duration.
Aviat Space Environ Med. 2002 Dec;73(12):1161-6.