Regulation of brain blood flow and oxygen delivery in elite breath-hold divers

Christopher K. Willie*, Philip N. Ainslie, Ivan Drvis, David B. MacLeod, Anthony R. Bain, Dennis Madden, Petra Zubin Maslov, Zeljko Dujic

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    30 Citations (Scopus)


    The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics were measured during maximum dry apneas in elite breath-hold divers (n=17). To isolate the effects of apnea and IBM from the concurrent changes on ABG, end-tidal forcing ('clamp') was then used to replicate an identical temporal pattern of decreasing arterial PO 2 (PaO 2) and increasing arterial PCO2 (PaCO2) while breathing. End-apnea PaO 2 ranged from 23 to 37 mm Hg (30±7 mm Hg). Elevation in mean arterial pressure was greater during apnea than during clamp reaching +54±24% versus 34±26%, respectively; however, CBF increased similarly between apnea and clamp (93.6±28% and 83.4±38%, respectively). This latter observation indicates that during the overall apnea period IBM per se do not augment CBF and that the brain remains sufficiently protected against hypertension. Termination of apnea was not determined by reduced cerebral oxygen delivery; despite 40% to 50% reductions in arterial oxygen content, oxygen delivery was maintained by commensurately increased CBF.

    Original languageEnglish
    Pages (from-to)66-73
    Number of pages8
    JournalJournal of Cerebral Blood Flow and Metabolism
    Issue number1
    Publication statusPublished - 10 Jan 2015


    • cerebral autoregulation
    • cerebral metabolism
    • hypertension
    • hypoxia


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