Hello,
I would like to know exactly what is known about diving yo-yo profiles, as long as you never reach a decompression ceiling. As I read on this forum in posts by Dr. Powell, the usual explanation that bubbles absorb gas and grow while ascending due to tissue off-gasing to the blood, and then get compressed when descending and thus manage to travel through the pulmonary filter abd to the arterial side, does not stand.
So, just to make sure: has it been experimentally observed that yo-yo profiles generate many bubbles, or are DCS-prone? Do you know of some references?
Since the usual explanation seems to be wrong, what are the possible explanations for the risks of yo-yo profiles?
Application: with my main certification agency, we regularly practice controlled buoyancy lift of a victim. A typical training profile is 4 repetitions of: descending to 20m, then ascending at ~12m/min to 3m. Is there any DCS risk with this profile if done at the very beginning of a dive? And if done while already partially saturated? (An instructor told me that about 1/4 of all DCS cases with PADI happen while practising this exercise for the Rescue Diver class, but maybe its due to trainees ascending too fast or breaking the surface).
Thanks for any good explanation!
I would like to know exactly what is known about diving yo-yo profiles, as long as you never reach a decompression ceiling. As I read on this forum in posts by Dr. Powell, the usual explanation that bubbles absorb gas and grow while ascending due to tissue off-gasing to the blood, and then get compressed when descending and thus manage to travel through the pulmonary filter abd to the arterial side, does not stand.
So, just to make sure: has it been experimentally observed that yo-yo profiles generate many bubbles, or are DCS-prone? Do you know of some references?
Since the usual explanation seems to be wrong, what are the possible explanations for the risks of yo-yo profiles?
Application: with my main certification agency, we regularly practice controlled buoyancy lift of a victim. A typical training profile is 4 repetitions of: descending to 20m, then ascending at ~12m/min to 3m. Is there any DCS risk with this profile if done at the very beginning of a dive? And if done while already partially saturated? (An instructor told me that about 1/4 of all DCS cases with PADI happen while practising this exercise for the Rescue Diver class, but maybe its due to trainees ascending too fast or breaking the surface).
Thanks for any good explanation!