Intravenous Perflubron Emulsion Administration Improves the Recovery of Auditory Evoked Potentials after Temporary Brain Stem Ischemia in Dogs

Abstract

OXYGENT, A SECOND-GENERATION perfluorocarbon (Perflubron) emulsion (Alliance Pharmaceutical Corporation, San Diego, CA) with superior oxygen delivery characteristics and greater stability than previous perfluorocarbon emulsions, was evaluated as a cerebroprotective agent in a dog model of partial brain stem ischemia. Six dogs were exposed to 20 minutes of isolated brain stem ischemia after receiving an intravenous bolus of Oxygent at a dose of 1.5 ml/kg. Brain stem auditory evoked potentials (BAEP) and regional cerebral blood flow were measured before and during the ischemia and for 5 hours after reperfusion. Changes in BAEP in this group were compared with those in four control dogs that experienced an identical ischemic period but that did not receive Oxygent. During the ischemic period, both control and Oxygent-treated animals experienced a dramatic decline in BAEP to under 10% of the baseline value. After reperfusion, the BAEP increased in both groups to between 50 and 70% of the baseline. In the Oxygent-treated group, the BAEP continued to recover to a final sustained level of over 80% of baseline. In contrast, the control animals suffered a drop in BAEP to 23% of baseline after the brief postischemic peak. The continued improvement in the BAEP in the Oxygent-treated group compared with the control groups suggests that Oxygent may be of some value as a protective agent to the brain stem during ischemia. This effect may be the result of improved oxygen delivery to the brain stem or may be related to other effects of Oxygent, such as reduction of reperfusion injury. Results suggest that Oxygent may be useful as a cerebroprotectant during cerebrovascular surgeries that require temporarily reducing blood flow to the brain stem.