Changes in brain barbiturate concentration in brain-dead rabbits.

Pentobarbital concentration was evaluated in the brain tissues of brain-dead rabbits. Pentobarbital was infused into the vein of Japanese white male rabbits at 60 mg/kg/h until an isoelectric EEG of the cortex was reached. Brain death was induced by inflation of a balloon catheter placed in the subdural space. The diagnosis of brain death was confirmed by a flat line ABR wave. A significant increase in heart rate, intracranial pressure, and mean arterial pressure, was observed following brain death induction. These parameters returned to below basal values within 60 mm. Immediately after, and at 6 h and 24 h after brain death, each group of rabbits was sacrificed by phenobarbital overdose, and brains were then removed for determination of pentobarbital concentration in the brain tissue. Blood pentobarbital disappeared about 18 h after brain death was induced. Although the brain pentobarbital concentration slightly decreased over time, a high concentration of pentobarbital remained in the brain 24 h after brain death was induced.