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| Title: | OXYGEN-ENHANCED BREATH-HOLD DIVING: O2 VS AIR. |
| Authors: | Vann, RD
Natoli, MJ
Hobbs, GW
Gabrielova, I
Hendricks, DM
Schinazi, EA
Pieper, CF
Pollock, NW |
| Keywords: | oxygen
breath-hold
diving
air
hyperventilation
consciousness |
| Issue Date: | 2000 |
| Abstract: | BACKGROUND: We reported results from Phase 2 (dry) of an oxygen breath-hold (BH) study at the 1998 UHMS Meeting. We report results from Phase 4 (wet) below (see additional data - Hobbs et al., this meeting). METHODS: Six male subjects (37±12 y [mean±SD], 21-57) completed 17 BH dives while immersed in a hyperbaric chamber (T=34.7±0.3°C) or pool (T=28.3±1.1°C). BH was preceded by normal breathing or hyperventilation (HV) (6-20 breaths/min. for 1 min) and a maximal breath of air or O2, BH activity was rest or modest exercise (75 watts cycling [chamber] or fin swimming [pool]). Pool dive depths were 2 or 12 ft. Measures included BH time (BHT) , distance swum (pool), and PETO2 & PETCO2 at BH breakpoint. Subjects reported symptoms associated with BH. RESULTS: BHT was associated with subject, gas, and exercise (p<0.0001) and HV (p=0.065). PETO2 was associated with gas and... BHTs, PETO2 mmHg, PETCO2 mmHg, Distance m; Air, 85±9, 52±6, 50±15; O2, 143±61, 372±96, 72±12, 73±20. ...depth (p<0.0001) and subject (p = 0.0285). PETCO2 was associated with subject, gas, exercise, and depth (p<0.0001). The table compares air and O2 BH for six subjects who hyperventilated and swam at 12 ft (pool). One O2 breath abolished hypoxia but increased end-BH hypercapnia. Individuals with lightheadedness or altered consciousness (n=36) had a mean breakpoint PETCO2 of 64±15 mmHg. PETCO2 for those not reporting symptoms (n=65) was 55±11 mmHg (p<0.026). One individual not included in the above data became unconscious at 240 s into a BH with HV, O2, and chamber exercise. He had previously completed an extreme 567 s BH to an 85 mmHg breakpoint PETCO2 (321±96 sand 68±55 mmHg, respectively, for all other trials). CONCLUSIONS: One Oz breath increased BHT by 70% over air and effectively eliminated the risk of ascent hypoxia. Concomitant elevation in breakpoint PETCO2 however, increased the risk of altered consciousness near end-BH. |
| Description: | Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org) |
| URI: | http://archive.rubicon-foundation.org/6739 |
| Appears in Collections: | UHMS Meeting Abstracts
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