title: Cerebral and peripheral hemodynamics and oxygenation during maximal dry breath-holds.
abstract: The effects of maximal apneas on cerebral and brachial blood flow and oxygenation are unknown in humans. Middle cerebral artery blood velocity (MCAV), cerebral and muscle oxygenation (Sc(O2) and Sm(O2)) and brachial blood flow (BBF) were measured during apneas in breath-hold divers (BHD) and non-divers (ND). Brain oxyhemoglobin (O(2)Hb) was maintained in both groups until the end of apnea, whereas deoxyhemoglobin increased more in BHD. Therefore, Sc(O2) decreased more in BHD due to longer apnea duration and smaller initial MCAV increase. MCAV increased significantly more in BHD versus ND at the end of apnea. Cerebral desaturation for approximately 13% occurred at the end of apnea in BHD despite increased cerebral oxygen delivery for approximately 50%. Larger reduction in muscle O(2)Hb was found in BHD, with similar peripheral vasoconstriction. These data indicate that BHD have decreased Sc(O2) at the end of breath-hold despite large increases in MCAV. This is partly due delayed initial cerebral vasodilation. This study provides further evidence for the oxygen-conserving effect in elite divers.
authors.affiliation: Department of Physiology, University of Split School of Medicine, Soltanska 2, 21000 Split, Croatia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Palada
authors.forename: Ante
authors.initials: A
authors.lastname: Obad
authors.forename: Darija
authors.initials: D
authors.lastname: Bakovic
authors.forename: Zoran
authors.initials: Z
authors.lastname: Valic
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ivancev
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Dujic
mesh_terms: D000328:Adult; D001049:Apnea / Q000503:physiopathology*; D001921:Brain / Q000098:blood supply*; D002560:Cerebrovascular Circulation; D004242:Diving / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply*; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D012039:Regional Blood Flow; D012119:Respiration; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D018709:Statistics, Nonparametric; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods
chemical_list: D010108:Oxyhemoglobins