Protection cérébrale: apport des agents anesthésiques intraveineux

Translated title of the contribution: Cerebral protection: role of intravenous anaesthetic agents

R. Tempelhoff, M. A. Cheng, G. Boulard, P. Ravussin

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The administration of an intravenous anaesthetic agent before experimental cerebral ischaemia in animals improves the functional and histological outcome. Cerebral ischaemia may be global or focal, complete or incomplete. Intravenous anaesthetic agents reduce the cerebral metabolic demand for oxygen (CMRO2) and abolish electrophysiological activity. This reflects a discontinuation of the functionnal neuronal activity with maintenance of its basic metabolic activity. The oxygen spared by the decrease in consumption, while reducing the functional activity, might be used by the neurons to sustain longer periods of ischaemia. This protective effect is also observed after pretreatment with either lidocaine or volatile agents, but their potentially deleterious vasodilating effect must be considered. Ketamine has recently been shown to antagonize NMDA receptors. The protective effect of barbiturates was experimentally demonstrated more than 30 years ago. They are still used as a reference. They reduce CMRO2, optimise the ratio between oxygen consumption and oxygen delivery and thus reduce cerebral blood flow and cerebral blood volume, as a result of the decrease of the metabolic demand. This might explain why a protective effect is seen in case of global or focal hypoxia with increased intracranial pressure, while no protection is documented in case of global cerebral ischaemia, such as after cardiac arrest, where EEG is immediately flat and ICP low. However, at doses required to obtain a protective effect, barbiturates induce deleterious side effects such as severe arterial hypotension, which limits their use. Cerebrovascular and cardiac surgery or surgery of the carotids are characterised by potentially ischaemic episodes which can be predicted. This allows proper application of protective measures, such as administration of intravenous anaesthetic agents. Not surprisingly, the only clinical documentation of a protective effect of barbiturates in man was achieved in patients undergoing cardiac surgery under extracorporeal circulation. The concept of pharmacological cerebral protection in case of cerebral ischaemia was investigated with other agents than barbiturates, such as etomidate, gamma-OH and propofol. Anaesthetic agents with their properties of reducing CMRO2 might be of benefit if applied early, by « buying timein the very first phase of the ischaemic insult.

Translated title of the contributionCerebral protection: role of intravenous anaesthetic agents
Original languageFrench
Pages (from-to)129-133
Number of pages5
JournalAnnales Francaises d'Anesthesie et de Reanimation
Volume14
Issue number1
DOIs
StatePublished - 1995

Keywords

  • Cerebral protection
  • Intravenous anaesthetics
  • Neuroanaesthesia

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