Effects des drogues utilisées en anesthésie et en réanimation neurochirurgicale sur le débit sanguin et le métabolisme du cerveau

Changes in cerebral blood flow (CBF) and in O2 consumption caused by anaesthetic agents were studied in 36 subjects in coma after cranial trauma. These changes can be divided into 3 groups: (1) Reduction in CBF and in O2 consumption of about the same percentage, after penthiobarbital, gamma-OH and alfathesin. (2) A reduction in CBF greater than in O2 consumption after diazepam and chlorpromazine. (3) Increase in CBF without significant change in O2 consumption after ketamine. The haemodynamic changes occur in the same direction whatever the initial value of the CBF (normal, hypoperfusion or hyperaemia). The reduction in CBF caused by gamma-OH is associated with a decrease in the arterio-venous difference in O2 (DAVO2). Gamma-OH also prevents the increase in DAVO2 observed in hypocapnia provoked by hyperventilation. These properties are an indication for using gamma-OH, alone or associated with hyperventilation, in reactive cerebral hyperaemia. Comparison of the E.E.G., CBF and cerebral O2 consumption shows that the E.E.G. changes produced by anaesthetic agents, such as fast spindles and burst suppression, are not related to any particular haemodynamic or metabolic state. The E.E.G. changes induced by penthiobarbital or diazepam can be corrected, at the same time as changes in CBF and O2 consumption, by injecting doxapram.