Cerebral autoregulation of blood velocity and volumetric flow during steady-state changes in arterial pressure

Jie Liu, Yong Sheng Zhu, Candace Hill, Kyle Armstrong, Takashi Tarumi, Timea Hodics, Linda S. Hynan, Rong Zhang

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

The validity of using transcranial Doppler measurement of cerebral blood flow velocity (CBFV) to assess cerebral autoregulation (CA) still is a concern. This study measured CBFV in the middle cerebral artery using transcranial Doppler and volumetric cerebral blood flow (CBF) in the internal carotid artery (ICA) using color-coded duplex ultrasonography to assess CA during steady-state changes in mean arterial pressure (MAP). Twenty-one healthy adults participated. MAP was changed stepwise by intravenous infusion of sodium nitroprusside and phenylephrine. Changes in CBFV, CBF, cerebrovascular resistance (CVR=MAP/CBF), or cerebrovascular resistance index (CVRi=MAP/CBFV) were measured to assess CA by linear regression analysis. The relationship between changes in ICA diameter and MAP was assessed. All values were normalized as percentage changes from baseline. Drug-induced changes in MAP were from -26% to 31%. Changes in CBFV and CVRi in response to MAP were linear, and the regression slopes were similar between middle cerebral artery and ICA. However, CBF in ICA remained unchanged despite large changes in MAP. Consistently, a steeper slope of changes in CVR relative to CVRi was observed (0.991 versus 0.804; P<0.05). The ICA diameter changed inversely in response to MAP (r=-0.418; P<0.05). These findings indicate that CA can be assessed with transcranial Doppler measurements of CBFV and CVRi in middle cerebral artery. However, it is likely to be underestimated when compared with the measurements of CBF and CVR in ICA. The inverse relationship between changes in ICA diameter and MAP suggests that large cerebral arteries are involved in CA.

Original languageEnglish (US)
Pages (from-to)973-979
Number of pages7
JournalHypertension
Volume62
Issue number5
DOIs
StatePublished - Nov 2013

Keywords

  • blood pressure
  • carotid artery internal
  • middle cerebral artery
  • ultrasonography Doppler transcranial

ASJC Scopus subject areas

  • Internal Medicine

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