Anaesthetic effects on regional cerebral blood flow and metabolism: three contemporary reasons to care

A basic understanding of how anaesthesia affects cerebral blood flow and cerebral metabolism is readily available as common textbookmaterial [1]. In general, most anaesthetic agents decrease cerebralmetabolism in a dose-dependentmannerwith variable effects on cerebral blood flow [2]. Despite a basic understanding of the cerebral effects of anaesthetics, the study of anaesthetic effects on cerebral blood flow andmetabolism remains a productive area of research with continued importance from both a clinical neuroanaesthesia and amechanism of anaesthesia frame of reference. This field of study is approaching a revolutionary phase that is partly technology driven (i.e. higher resolution scanners, agent-specific ligands, newer imaging methodology), but which is also a direct result of the plethora of data that now exists regarding the effects of various agents on cerebral blood flow and metabolism. This large literature allows conclusions to be drawn that encompass integrated observations about various specific agents and across various classes of agents. This article, therefore, will not attempt a comprehensive reviewof the entire literature [2], rather it will focus on integrating some general observations into a cohesive theoretical framework with the aim of providing additional insights. Three contemporary reasons to care about the study of anaesthetic effects on cerebral blood flow and metabolism can be organised as relating to: (1) the documented commonalities among agents, (2) the documented differences between agents, and (3) the detailed effects related to specific agents. These reasons are expanded upon more fully below.