Cerebral Autoregulation is Influenced by Carbon Dioxide Levels in Anoxic Brain Injury

Excerpt

Post cardiac arrest (CA) syndrome is a severe condition associated with high mortality and significant long-term disabilities among survivors, mainly because of brain injury. Whether alterations in brain hemodynamics after the return of spontaneous circulation significantly contribute to this injury remains controversial. Pressure cerebral autoregulation (CaR) is an intrinsic cerebral arteriolar homeostatic mechanism that regulates cerebral blood flow (CBF) during fluctuations in cerebral perfusion pressure (CPP) by responding with vasoconstriction or vasodilation to increased or decreased CPP, respectively. CaR is altered in survivors of CA, and its alterations correlate to outcome [1]. Arterial partial pressure of carbon dioxide (PaCO₂) also influences the cerebrovascular tone directly through modifications in perivascular pH, determining cerebral vasoconstriction or vasodilation in case of hypocapnia or hypercapnia, respectively. Such modification in the cerebrovascular tone could potentially affect CaR efficiency; however, this issue remains controversial. …