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I have been reading material on the development of decompression tables and current research on the subject. I came across "A deep stop during decompression from 82 fsw (25 m) significantly reduces bubbles and fast tissue gas tensions." by MARRONI et al from UHM 2004, Vol. 31, No. 2.
The paper starts out with a precursory introduction as to the reason for the research, noting that:
The research involving over 1,400 divers found that divers following normal recreational protocols had bubble formation 87% of the time, and that 67% of the time these were high grade bubbles.
What becomes amazing in the research is that when looking at linear ascent rates,
I'm sure there is more recent research on the relationship between ascent rates, stop levels, and bubble formation than this 2004 paper. I'm wondering if:
a) someone can point me to some of the better regarded research?
b) has this research made it's way into any recreational agency's diving instruction?
c) what is the effect of being focused on fast tissues have on gas-tensions in slower tissues? On longer deep dives including deep stops do slower tissue compartments become the controlling compartment?
Thanks in advance!
The paper starts out with a precursory introduction as to the reason for the research, noting that:
This clearly has some serious implications for recreational divers interested in conservative diving practices. While the risk for DCS is relatively low in recreational divers, it still does exist.Experience in recreational divers has shown that 65% of treated DCS cases are neurological. They usually involve the spinal cord which has a “tissue” half time of only 12.5 minutes (4). During a 30 m (100 fsw) dive of 25 minutes, the 5 and 10 minute tissues will attain a high degree of saturation. Even though current computer models de-emphasize the importance of these tissues, these may, in fact, be controlling factors. Significantly more ascent time may therefore be required to off-gas these critical fast tissues and avoid neurological DCS. Indeed, the original Haldane table (2) for a 30 m (100 fsw)/25 minute dive required decompression stops at 9, 6 and 3 m (30, 20 and 10 fsw) for a total decompression time of 19 minutes. Yet today, with an ascent of 9 m (30 fsw)/minute and a ‘safety stop’ at 5 m (15 fsw) for 3 minutes, the recreational scuba diver is on the surface in only 6 minutes. This may be far too short for adequate desaturation of a 5 minute tissue that has attained a high degree of saturation.
The research involving over 1,400 divers found that divers following normal recreational protocols had bubble formation 87% of the time, and that 67% of the time these were high grade bubbles.
What becomes amazing in the research is that when looking at linear ascent rates,
The final conclusion is that a an ascent rate of 10m/min with deep and shallow stops is an optimal risk reduction profile.This research with human divers produced two primary findings: (1) Slow ascents (3m/min) produced greater bubble grades than faster ascents (see Figure 5); and (2) the inclusion of a deep stop together with a shallow stop yielded the lowest bubble grades (see Figure 6). Therefore, contrary to popular belief, this study has indicated that a slow, linear ascent may produce significantly more bubbles than a more rapid ascent rate with a deep and shallow stop.
I'm sure there is more recent research on the relationship between ascent rates, stop levels, and bubble formation than this 2004 paper. I'm wondering if:
a) someone can point me to some of the better regarded research?
b) has this research made it's way into any recreational agency's diving instruction?
c) what is the effect of being focused on fast tissues have on gas-tensions in slower tissues? On longer deep dives including deep stops do slower tissue compartments become the controlling compartment?
Thanks in advance!