title: Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation.
abstract: Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation in scuba divers was evaluated. Six volunteers participated in four diving protocols, with 2 wk of recovery between dives. On dive 1, before diving, all divers breathed normally for 20 min at the surface of the sea (Air). On dive 2, before diving, all divers breathed 100% oxygen for 20 min at the surface of the sea [normobaric oxygenation (NBO)]. On dive 3, before diving, all divers breathed 100% O2 for 20 min at 6 m of seawater [msw; hyperbaric oxygenation (HBO) 1.6 atmospheres absolute (ATA)]. On dive 4, before diving, all divers breathed 100% O2 for 20 min at 12 msw (HBO 2.2 ATA). Then they dove to 30 msw (4 ATA) for 20 min breathing air from scuba. After each dive, blood samples were collected as soon as the divers surfaced. Bubbles were measured at 20 and 50 min after decompression and converted to bubble count estimate (BCE) and numeric bubble grade (NBG). BCE and NBG were significantly lower in NBO than in Air [0.142+/-0.034 vs. 0.191+/-0.066 (P<0.05) and 1.61+/-0.25 vs. 1.89+/-0.31 (P<0.05), respectively] at 20 min, but not at 50 min. HBO at 1.6 ATA and 2.2 ATA has a similar significant effect of reducing BCE and NBG. BCE was 0.067+/-0.026 and 0.040+/-0.018 at 20 min and 0.030+/-0.022 and 0.020+/-0.020 at 50 min. NBG was 1.11+/-0.17 and 0.92+/-0.16 at 20 min and 0.83+/-0.18 and 0.75+/-0.16 at 50 min. Prebreathing NBO and HBO significantly alleviated decompression-induced platelet activation. Activation of CD62p was 3.0+/-0.4, 13.5+/-1.3, 10.7+/-0.9, 4.5+/-0.7, and 7.6+/-0.8% for baseline, Air, NBO, HBO at 1.6 ATA, and HBO at 2.2 ATA, respectively. The data show that prebreathing oxygen, more effective with HBO than NBO, decreases air bubbles and platelet activation and, therefore, may be beneficial in reducing the development of decompression sickness.
authors.affiliation: Department of Basic and Applied Medical Sciences, Ud'A Chieti-Pescara, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Bosco
authors.forename: Zhong-jin
authors.initials: ZJ
authors.lastname: Yang
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Di Tano
authors.forename: Enrico M
authors.initials: EM
authors.lastname: Camporesi
authors.forename: Fabio
authors.initials: F
authors.lastname: Faralli
authors.forename: Fabio
authors.initials: F
authors.lastname: Savini
authors.forename: Angelo
authors.initials: A
authors.lastname: Landolfi
authors.forename: Christian
authors.initials: C
authors.lastname: Doria
authors.forename: Giorgio
authors.initials: G
authors.lastname: Fanò
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D003664:Decompression / Q000009:adverse effects; D003665:Decompression Sickness / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D004242:Diving; D004618:Embolism, Air / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D006931:Hyperbaric Oxygenation; D007101:Immersion; D001239:Inhalation; D039661:Integrin beta3 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage*; D019007:P-Selectin / Q000097:blood; D015539:Platelet Activation; D040201:Platelet Membrane Glycoprotein IIb / Q000097:blood; D013997:Time Factors; D018608:Ultrasonography, Doppler; D055815:Young Adult
chemical_list: C061248:ITGB3 protein, human; D039661:Integrin beta3; D019007:P-Selectin; D040201:Platelet Membrane Glycoprotein IIb; D010100:Oxygen