Dynamic cerebral autoregulation in response to prolonged hypoxic exposure

Hayato Tsukamoto, Benjamin Stacey, Takuro Washio, Angelo Iannetelli, Tom Owens, Thomas A. Calverley, Lewis Fall, Christopher Marley, Shigehiko Ogoh, Damian Bailey

Allbwn ymchwil: Cyfraniad at gynhadleddCrynodebadolygiad gan gymheiriaid


Dynamic cerebral autoregulation (dCA) acts to maintain relatively constant cerebral blood flow to accommodate dynamic fluctuations in perfusion pressure to maintain cerebral bioenergetic function. However, to what extent systemic hypoxaemia impacts regional dCA remains unclear, complicated in part by differences in measurement techniques and exposure duration (Bailey et al., 2009; Stacey et al., 2023). To examine this, twelve healthy males were exposed to two trials (normoxia vs. hypoxia; 12%O2) in a single-blinded, randomized cross-over design. Using transcranial Doppler ultrasound, middle (anterior circulation) and posterior cerebral artery blood velocities (MCAv and PCAv) were measured for 5-min during 0.5, 2, 4, and 6-h passive exposure to normoxia and hypoxia, respectively. At the same time point, beat-by-beat arterial blood pressure was measured using finger photoplethysmography. Transfer function analysis estimated dCA in the very-low and low frequency bands (VLF; 0.02-0.07 Hz and LF; 0.07-0.20 Hz). A repeated two-way ANOVA indicated that hypoxia reduced VLF phase (P < 0.001) and increased VLF gain (P < 0.001) and VLF coherence (P = 0.003) in the posterior circulation. This was comparable to that of the anterior circulation where equally, VLF gain and VLF coherence increased (P = 0.047 and P = 0.002, respectively) and VLF phase decreased (P = 0.006). These findings indicate a more pressure-passive relationship for both the anterior and posterior circulation and is consistent with previous research in the anterior circulation (Iwasaki et al., 2007; Bailey et al., 2009; Subudhi et al., 2009, 2010; Katsukawa et al., 2012). This study is the first to examine dCA in the posterior circulation under conditions of prolonged hypoxia. Although speculative, these findings may be attributable to increased oxidative-inflammatory-nitrosative stress characterized by free radical-mediated scavenging of nitric oxide (Bailey et al., 2009) and/or elevated sympathetic activation, that collectively conspire to decrease dCA (Zhang et al., 2002).
Iaith wreiddiolSaesneg
StatwsCyhoeddwyd - 2023
DigwyddiadAnnual Meeting of the Cerebrovascular Research Network (CARNet) - Taipei, Taiwan
Hyd: 25 Hyd 202327 Hyd 2023


CynhadleddAnnual Meeting of the Cerebrovascular Research Network (CARNet)
Cyfeiriad rhyngrwyd

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