Influence of blood pressure and cardiac output on cerebral blood flow and autoregulation in acute stroke measured by TCD

Abstract

Although the dependence of cerebral perfusion on blood pressure has been well studied, little data is available about the effect cardiac output has on cerebral flow velocity and autoregulation, particularly during acute stroke. To improve cerebral perfusion, we treated 10 patients who suffered from an acute ischemic stroke of the middle cerebral artery with a hypervolemic hemodilution combined with dopamine‐dobutamine. The influence of blood pressure and cardiac output on the blood flow velocity in the middle cerebral artery was measured using transcranial doppler sonography (TCD). Under the therapy, a dosage‐dependent increase of 12% in blood pressure (BP) and 53% increase in cardiac output was observed. There was a significant (p > 0.01) correlation between TCD‐mean flow velocity (Vm) and cardiac output (r = 0.33) as well as between Vm and blood pressure (r = 0.52) on the affected side. The unaffected side showed no correlation between Vm and cardiac output (r = 0.01), or between Vm and blood pressure (r = 0.03). Systolic flow velocity increased significantly in both hemispheres. As an expression of increasing cerebral vascular resistance, the pulsating index (PI) increased significantly (p > 0.01) in the affected hemisphere as well as in the unaffected hemisphere. This suggests that during acute stroke blood flow velocity and autoregulation in the affected vascular region depend not only on cerebral perfusion pressure but also on CO levels.