Barbiturates in neuroanesthesia and neuro-intensive care.

Barbiturates reduce cerebral activity which again reduce the cerebral metabolic rate probably by activating chloride channels and potentiating GABA's effects on these channels. Protection of the brain against hypoxia might theoretically occur by this mechanism, by vasoconstriction or by inhibiting calcium or glutamate. The barbiturates appear to have a positive effect in head-injury patients with high ICP uncontrollable by conventional therapy (in one study 5% of patients with a GCS < or = 7), and in animal studies of regional ischemia. No effect has been established in complete cerebral ischemia (cardiac arrest). The barbiturates have a depressant effect on the cardiovascular and respiratory systems, and the patients require intensive care. Thus there are some indications in the literature that the barbiturate treatment itself causes complications, and it is possible that this might cancel a potential beneficial effect in some patients. Clinically, the barbiturates are effective anticonvulsants, can be used in an attempt to control an elevated ICP uncontrollable by conventional means, and during transient ischemic episodes in the operating room with adequate monitoring and support systems already in place.