Cerebral Perfusion and Cerebral Autoregulation after Cardiac Arrest

Abstract

Out of hospital cardiac arrest is the leading cause of death in industrialized countries. Recovery of hemodynamics does not necessarily lead to recovery of cerebral perfusion. The neurological injury induced by a circulatory arrest mainly determines the prognosis of patients after cardiac arrest and rates of survival with a favourable neurological outcome are low. This review focuses on the temporal course of cerebral perfusion and changes in cerebral autoregulation after out of hospital cardiac arrest. In the early phase after cardiac arrest, patients have a low cerebral blood flow that gradually restores towards normal values during the first 72 hours after cardiac arrest. Whether modification of the cerebral blood flow after return of spontaneous circulation impacts patient outcome remains to be determined.

Figure 1

Cerebral autoregulation maintains cerebral blood flow at a constant level when the mean arterial pressure is between approximately 50 and 150 mmHg (the plateau phase).

Figure 2

More recent data support the opinion that cerebral autoregulation does not maintain constant blood flow through a broad MAP range of 50–150 mmHg, but probably in a smaller range. Cerebral autoregulation is more effective in the range above baseline mean arterial pressure, compared to the range below.