Delayed Pentobarbital Therapy of Acute Focal Cerebral Ischemia

SUMMARY The efficacy of pentobarbital in the delayed treat-ment of acute cerebral ischemia was investigated in cats. Cerebral ischemia was produced by left middle cerebral artery (LMCA) liga-tion. Ten cats received 50 mg/kg of pentobarbital prior to ligation; a second group of 10 cats received the same dose of pentobarbital 2 hrs after ligation, and the control group of 7 cats received no pento-barbital. Brains were removed after spontaneous or induced death and the volume infarction was determined histologically. It was found that the volume of brain infarction in the group receiving pento-barbital 2 hrs after ligation was significantly less than that of the con-trol group, which received no pentobarbital; but the volume of infarc-tion in the former group was significantly greater than that found in the experimental group, which received pentobarbital prior to liga-tion. However, the mortality after LMCA ligation was higher in the 2 experimental groups, which received pentobarbital therapy, than in the control group, which did not receive pentobarbital. An hypothesis was advanced, which speculated that secondary adrenal insufficiency and altered cardiovascular function accounted for the increased mortality after pentobarbital treatment of patients with ischemic stroke. RECENTLY PENTOBARBITAL, given as anesthesia, was shown to prevent brain necrosis in dogs and baboons which were subjected to acute cerebral ischemia.1"3 How-ever, if pentobarbital is to be useful in the treatment of patients with acute occlusion of cerebral arteries, it must be effective when administered after arterial obstruction has oc-curred.4 This realization, together with the observation by Little el al.h that during the first 3 hrs of cerebral ischemia only slight microcirculatory impairment was detected in the affected brain tissue, provoked the present work. In the pres-ent study, the volume of resultant brain necrosis after left middle cerebral artery (LMCA) ligation was determined when pentobarbital was administered 2 hrs after occlusion. These results were compared with those obtained from 2 other experimental groups subjected to the same kind of ischemic stroke; 1 received no pentobarbital (control group) and the other received pentobarbital prior to arterial li-gation