Figure 2. The severity of histologic damage in the neocortex after either incomplete (A) or near-complete (B) forebrain ischemia. Horizontal bars depict median values. Isoflurane caused reduced damage after near-complete ischemia when compared with either ketamine or fentanyl - nitrous oxide (P = 0.02). There was no effect for anesthetic on histologic outcome from incomplete ischemia. 0 = no observed histologic change; 1 = 1 - 5% neurons damaged; 2 = 6 - 50% neurons damaged; 3 = 51 - 100% of neurons damaged; and 4 = infarction.