tinman
Contributor
AquaTec: I was intrigued by your suggestion of face immersion pre-dive to improve SAC rates.
Dr. Lundgren, MD PHD, Dir. of Centre for Research, Special Environments, U oF Buffalo, spoke at the Nov 2 Great Lakes Undersea & Hyperbaric Med. Society Chapter mtg. His subject was the results of Chamber studies done on the family of Italian record freedivers (Father & two daughters, I'm sure someone on the board knows their names). Some of my rough notes:
Started with 7.5liters went to 1.5liters from 1 ATM to 5ATM Studied father and two daughters and control subjects in 30 and 20 C water tests at various simulated depths in hyperbaric chamber.
Vasoconstriction in "cold" H20 (20 C) caused huge spikes in Blood Pressure: described as "Dive Response", holding breath or cooling face reduced Heart Rate but spiked BP from ~ 120/80 to ~ 300/200 in some instances. Heart rate drops recorded from 80 to as low as ~5-10 per minute. Could possibly explain arrythmias and sudden death in some dive situations (Makes sense with older, less fit divers - 300 Systolic!). Compared to control subjects with no special training, freedivers O2 consumption improved overtime and were more resistant to the breath response (C02 buildup) - natural or acquired?. {This is a broad paraphrase by a layman diver - hopefully not a disservice to an amazing man who has numerous patents in scuba gear, etc. Perhaps DocV or others can do justice to this subject}
What I take from this is that your SAC rate would certainly go down. I posed the question to Dr. Lundgren whether he would suggest initial face exposure to cold water by Great Lakes divers as a pre-dive drill - I do it to help clear my mask and to make sure the mask is properly seated inside my hood. He responded that he wouldn't recommend it. Unfortunately, I didn't get a chance to get him to elaborate on this response.
I'm diving at this time of year in 37-45 C lake water - not much different than deep dives anywhere I suppose. Would expect similar or more dramatic results in some divers - possible swallow depth blackout risk in the unfit? 5 minutes face down exercise could be an interesting acid test for some if they REALLY want to make the dive! Fascinating subject but worth being aware of if diving with unfit divers unacquainted with cold water dives or diving with inadequate exposure protection this time of year....
Dr. Lundgren, MD PHD, Dir. of Centre for Research, Special Environments, U oF Buffalo, spoke at the Nov 2 Great Lakes Undersea & Hyperbaric Med. Society Chapter mtg. His subject was the results of Chamber studies done on the family of Italian record freedivers (Father & two daughters, I'm sure someone on the board knows their names). Some of my rough notes:
Started with 7.5liters went to 1.5liters from 1 ATM to 5ATM Studied father and two daughters and control subjects in 30 and 20 C water tests at various simulated depths in hyperbaric chamber.
Vasoconstriction in "cold" H20 (20 C) caused huge spikes in Blood Pressure: described as "Dive Response", holding breath or cooling face reduced Heart Rate but spiked BP from ~ 120/80 to ~ 300/200 in some instances. Heart rate drops recorded from 80 to as low as ~5-10 per minute. Could possibly explain arrythmias and sudden death in some dive situations (Makes sense with older, less fit divers - 300 Systolic!). Compared to control subjects with no special training, freedivers O2 consumption improved overtime and were more resistant to the breath response (C02 buildup) - natural or acquired?. {This is a broad paraphrase by a layman diver - hopefully not a disservice to an amazing man who has numerous patents in scuba gear, etc. Perhaps DocV or others can do justice to this subject}
What I take from this is that your SAC rate would certainly go down. I posed the question to Dr. Lundgren whether he would suggest initial face exposure to cold water by Great Lakes divers as a pre-dive drill - I do it to help clear my mask and to make sure the mask is properly seated inside my hood. He responded that he wouldn't recommend it. Unfortunately, I didn't get a chance to get him to elaborate on this response.
I'm diving at this time of year in 37-45 C lake water - not much different than deep dives anywhere I suppose. Would expect similar or more dramatic results in some divers - possible swallow depth blackout risk in the unfit? 5 minutes face down exercise could be an interesting acid test for some if they REALLY want to make the dive! Fascinating subject but worth being aware of if diving with unfit divers unacquainted with cold water dives or diving with inadequate exposure protection this time of year....
