Directional sensitivity of dynamic cerebral autoregulation during spontaneous fluctuations in arterial blood pressure at rest

J Cereb Blood Flow Metab. 2023 Apr;43(4):552-564. doi: 10.1177/0271678X221142527. Epub 2022 Nov 24.

Abstract

Directional sensitivity, the more efficient response of cerebral autoregulation to increases, compared to decreases, in mean arterial pressure (MAP), has been demonstrated with repeated squat-stand maneuvers (SSM). In 43 healthy subjects (26 male, 23.1 ± 4.2 years old), five min. recordings of cerebral blood velocity (bilateral Doppler ultrasound), MAP (Finometer), end-tidal CO2 (capnograph), and heart rate (ECG) were obtained during sitting (SIT), standing (STA) and SSM. A new analytical procedure, based on autoregressive-moving average models, allowed distinct estimates of the autoregulation index (ARI) by separating the MAP signal into its positive (MAP+D) and negative (MAP-D) derivatives. ARI+D was higher than ARI-D (p < 0.0001), SIT: 5.61 ± 1.58 vs 4.31 ± 2.16; STA: 5.70 ± 1.24 vs 4.63 ± 1.92; SSM: 4.70 ± 1.11 vs 3.31 ± 1.53, but the difference ARI+D-ARI-D was not influenced by the condition. A bootstrap procedure determined the critical number of subjects needed to identify a significant difference between ARI+D and ARI-D, corresponding to 24, 37 and 38 subjects, respectively, for SSM, STA and SIT. Further investigations are needed on the influences of sex, aging and other phenotypical characteristics on the phenomenon of directional sensitivity of dynamic autoregulation.

Keywords: Cerebral autoregulation; cerebral blood flow; multivariate modelling; posture; squat-stand maneuver.

MeSH terms

  • Adolescent
  • Adult
  • Arterial Pressure*
  • Blood Pressure / physiology
  • Cerebrovascular Circulation / physiology
  • Homeostasis / physiology
  • Humans
  • Male
  • Ultrasonography, Doppler, Transcranial*
  • Young Adult