Perioperative cerebral ischemia and the possibility of neuroprotection by inhalational anesthetics

Deteriorated neurological outcome is not rare after major surgeries. With aging of the surgical population in Japan, an increasing frequency of perioperative cerebral ischemia is expected. To avoid neurological deterioration after surgery and general anesthesia, especially in high-risk patients, it is important to provide appropriate CNS-oriented anesthesia management. Controlling factors such as cerebral perfusion pressure, arterial blood gases, blood glucose concentration and body temperature may influence brain metabolism and neurological outcome. Inhalational anesthetics may also play an important role in perioperative neurological management, because numerous studies have demonstrated some degree of neuroprotective effect with halothane, sevoflurane, desflurane and isoflurane. Among these inhalational anesthetics, isoflurane has been most extensively studied regarding neuroprotection against cerebral ischemic insult. Although no clinical outcome trials have been performed, both in vivo and in vitro studies have consistently shown that the isoflurane provides neuroprotection. However, it is also suggested that factors such as sympathetic reactivity, brain temperature, anesthetic dosage, timing of anesthetic administration, and co-administration of nitrous oxide might affect the neuroprotective effect of isoflurane.