Ischemic Stroke in the ICU: Bedside Monitoring of the Cerebral Autoregulation Status by Transcranial Doppler (TCD/TCCS) in the Acute Stage

Abstract

Measuring cerebral autoregulation (CA), on par with cerebrovascular reactivity, tests different properties of the cerebrovascular system. They provide a window into the ability of the cerebral circulation to react to variations in pressure/flow, metabolites, and gases. CA evaluation, in particular, assesses the changes in cerebrovascular resistance in response to perfusion changes. Cerebral autoregulation can be measured with pressure manipulation or using spontaneous fluctuations of blood pressure (arterial line or plethysmography) and cerebral flow velocity (transcranial Doppler). Transfer function characterizes cerebral autoregulation in frequency domain by three parameters: phase, gain, and coherence. Dynamic cerebral autoregulation has been shown to play a considerable role in the study and evaluation of acute cerebral ischemia. The results obtained encourage the development of different lines of research with potential therapeutic interest that may benefit the prognosis of patients with acute ischemic stroke.