The effects of sevoflurane and isoflurane on intracranial pressure following diffuse brain injury in rats

Abstract

Twenty-four adult Wistar rats weighting 220-290 g were anesthetized with an intraperitoneal injection of 30 mg/kg sodium thiopental and a tracheostomy was performed. Following diffuse impact-acceleration brain injury (BI), animals were paralyzed and mechanically ventilated with %30 O<inf>2</inf> in N<inf>2</inf>O. The rats were randomly assigned to two groups. Each group received one of the two volatile anesthetic agents which were administered in 0.5, 0.75, 1.0 and 1.25 MAC end-tidal concentrations for 30 minutes each, respectively. Anesthesia was maintained with 0.75 MAC during last hour of the study period. ICP, MAP, rectal and intrahemispheric temperature and end-tidal volatile anesthetics concentration were monitored continuously for 3 hours. At baseline, there were no significant differences between two groups with regard to the monitored physiologic variables. MAP decreased in the sevoflurane group after 45 minutes and in isoflurane group after 30 minutes (p<0.05, p<0.01, p<0.001). ICP rose significantly at 30 minutes in the sevoflurane group (p<0.05) and remain elevated until the end of the study period (p<0.05). ICP did not change significantly in the group that received isoflurane. CPP changed in parallel with MAP, with the reduction in the sevoflurane group being more pronounced than that in the isoflurane group (p<0.05, p<0.01, p<0.001). The results showed that, in the presence of diffuse BI, animals that were anesthetized with sevoflurane had higher ICP than those anesthetized with isoflurane. This suggests that, in the clinical setting sevoflurane should not be chosen above isoflurane for anesthetic management of the diffuse BI patient group.