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| Title: | Effect of varying deep stop times and shallow stop times on precordial bubbles after dives to 25 msw (82 fsw). |
| Authors: | Bennett, PB
Marroni, A
Cronje, FJ
Cali-Corleo, R
Germonpre, P
Pieri, M
Bonuccelli, C
Leonardi, MG
Balestra, C |
| Keywords: | Decompression
DECOMPRESSION SICKNESS
deep stops
DOPPLER
Humans |
| Issue Date: | 2007 |
| Publisher: | Undersea and Hyperbaric Medical Society, Inc. |
| Citation: | Undersea Hyperb Med. 2007 Nov-Dec;34(6):399-406. |
| Abstract: | In our previous research, a deep 5-min stop at 15 msw (50 fsw), in addition to the typical 3-5 min shallow stop, significantly reduced precordial Doppler detectable bubbles (PDDB) and "fast" tissue compartment gas tensions during decompression from a 25 msw (82 fsw) dive; the optimal ascent rate was 10 msw (30 fsw/min). Since publication of these results, several recreational diving agencies have recommended empirical stop times shorter than the 5 min stops that we used, stops of as little as 1 min (deep) and 2 min (shallow). In our present study, we clarified the optimal time for stops by measuring PDDB with several combinations of deep and shallow stop times following single and repetitive open-water dives to 25 msw (82 fsw) for 25 mins and 20 minutes respectively; ascent rate was 10 msw/min (33 fsw). Among 15 profiles, stop time ranged from 1 to 10 min for both the deep stops (15 msw/50 fsw) and the shallow stops (6 msw/20 fsw). Dives with 2 1/2 min deep stops yielded the lowest PDDB scores--shorter or longer deep stops were less effective in reducing PDDB. The results confirm that a deep stop of 1 min is too short--it produced the highest PDDB scores of all the dives. We also evaluated shallow stop times of 5, 4, 3, 2 and 1 min while keeping a fixed time of 2.5 min for the deep stop; increased times up to 10 min at the shallow stop did not further reduce PDDB. While our findings cannot be extrapolated beyond these dive profiles without further study, we recommend a deep stop of at least 2 1/2 mins at 15 msw (50 fsw) in addition to the customary 6 msw (20 fsw) for 3-5 mins for 25 meter dives of 20 to 25 minutes to reduce PDDB. |
| Description: | Undersea & Hyperbaric Medicine : Journal of the Undersea and Hyperbaric Medical Society, Inc. |
| URI: | http://archive.rubicon-foundation.org/7901 |
| ISSN: | 1066-2936 |
| Appears in Collections: | Undersea and Hyperbaric Medicine Journal
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| 18251436.pdf | | 1351Kb | Adobe PDF | View/Open |
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