Differential systolic and diastolic regulation of the cerebral pressure-flow relationship during squat-stand manoeuvres

Jonathan D. Smirl*, Alexander D. Wright, Philip N. Ainslie, Yu Chieh Tzeng, Paul van Donkelaar

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


    Objective: Cerebral pressure-flow dynamics are typically reported between mean arterial pressure and mean cerebral blood velocity. However, by reporting only mean responses, potential differential regulatory properties associated with systole and diastole may have been overlooked. Materials and methods: Twenty young adults (16 male, age: 26.7 ± 6.6 years, BMI: 24.9 ± 3.0 kg/m 2 ) were recruited for this study. Middle cerebral artery velocity was indexed via transcranial Doppler. Cerebral pressure-flow dynamics were assessed using transfer function analysis at both 0.05 and 0.10 Hz using squat-stand manoeuvres. This method provides robust and reliable measures for coherence (correlation index), phase (timing buffer) and gain (amplitude buffer) metrics. Results: There were main effects for both cardiac cycle and frequency for phase and gain metrics (p < 0.001). The systolic phase (mean ± SD) was elevated at 0.05 (1.07 ± 0.51 radians) and 0.10 Hz (0.70 ± 0.46 radians) compared to the diastolic phase (0.05 Hz: 0.59 ± 0.14 radians; 0.10 Hz: 0.33 ± 0.11 radians). Conversely, the systolic normalized gain was reduced (0.05 Hz: 0.49 ± 0.12%/%; 0.10 Hz: 0.66 ± 0.20%/%) compared to the diastolic normalized gain (0.05 Hz: 1.46 ± 0.43%/%; 0.10 Hz: 1.97 ± 0.48%/%). Conclusions: These findings indicate there are differential systolic and diastolic aspects of the cerebral pressure-flow relationship. The oscillations associated with systole are extensively buffered within the cerebrovasculature, whereas diastolic oscillations are relatively unaltered. This indicates that the brain is adapted to protect itself against large increases in systolic blood pressure, likely as a mechanism to prevent cerebral haemorrhages.

    Original languageEnglish
    Title of host publicationActa Neurochirurgica, Supplementum
    Number of pages6
    Publication statusPublished - 1 Jan 2018

    Publication series

    NameActa Neurochirurgica, Supplementum
    ISSN (Print)0065-1419
    ISSN (Electronic)2197-8395


    • Blood pressure
    • Cardiac cycle
    • Cerebral autoregulation
    • Cerebral blood flow
    • Middle cerebral artery
    • Transfer function analysis


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