Is the cushing mechanism a dynamic blood pressure-stabilizing system? Insights from granger causality analysis of spontaneous blood pressure and cerebral blood flow

Saqib Saleem, Paul D. Teal, Connor A. Howe, Michael M. Tymko, Philip N. Ainslie, Yu Chieh Tzeng*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)

    Abstract

    Blood pressure (BP) regulation is widely recognized as being integral to the control of end-organ perfusion, but it remains unclear whether end-organ perfusion also plays a role in driving changes in BP. A randomized and placebo-controlled study design was followed to examine feedback relationships between very-low-frequency fluctuations in BP and cerebral blood flow (CBF) in humans under placebo treatment and α1-adrenergic blockade. To determine the causal relations among hemodynamic variables, BP, middle cerebral artery blood velocity (MCAv), and end-tidal CO2 time-series were decimated, low-pass filtered (<0.07 Hz), fitted to vector autoregressive models, and tested for Granger causality in the time domain. Results showed that 1) at baseline, changes in BP and MCAv often interact in a closed-loop; and 2) α1-adrenergic blockade results in the dominant causal direction from BP to MCAv. These results suggest that, between subjects, cerebral pressure-flow interactions at time scales < 0.07 Hz are frequently bidirectional, and that in the presence of an intact autonomic nervous system BP may be regulated by reflex pathways sensitive to changes in CBF.

    Original languageEnglish
    Pages (from-to)R484-R495
    JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
    Volume315
    Issue number3
    DOIs
    Publication statusPublished - 1 Sep 2018

    Keywords

    • Blood pressure
    • Cerebral blood flow
    • Cushing mechanism
    • Granger causality
    • Sympathetic control

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