title: Role of cerebral blood flow in extreme breath holding.
abstract: The role of cerebral blood flow (CBF) on a maximal breath-hold (BH) in ultra-elite divers was examined. Divers (n = 7) performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg). Arterial blood gases and CBF were measured prior to (baseline), and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO2) by about 26% (p < 0.01). Indomethacin reduced maximal BH time from 339 ± 51 to 319 ± 57 seconds (p = 0.04). In both conditions, the CDO2remained unchanged from baseline to the termination of apnea. At BH termination, arterial oxygen tension was higher following oral administration of indomethacin compared to control (4.05 ± 0.45 vs. 3.44 ± 0.32 kPa). The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01). These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H+washout, and therefore central chemoreceptive drive to breathe, rather than to CDO2.
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Bain
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Ainslie
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Hoiland
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Chris K
authors.initials: CK
authors.lastname: Willie
authors.affiliation: Department of Anesthesiology, Duke University Medical Center, Durham, NC, United States of America.
authors.forename: David B
authors.initials: DB
authors.lastname: MacLeod
authors.affiliation: Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Dennis
authors.initials: D
authors.lastname: Madden
authors.affiliation: Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Petra Zubin
authors.initials: PZ
authors.lastname: Maslov
authors.affiliation: School of Kinesiology, University of Zagreb, Zagreb, Croatia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Drviš
authors.affiliation: Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Željko
authors.initials: Ž
authors.lastname: Dujić
keywords: Apnea; Cerebral oxygen delivery; Hypercapnia; Hypoxia; Indomethacin