Effect of Treatment with Fluosol and Mannitol during Temporary Middle Cerebral Artery Occlusion in Cats

Four groups of seven cats each were subjected to 6 hours of temporary middle cerebral artery (MCA) occlusion followed by reperfusion. During the first 30 minutes of the occlusion, Group 1 received 20% Fluosol-DA (FDA) and Group 2 received 20% FDA and mannitol; Group 3 received 20% FDA and mannitol 30 minutes before the occlusion, and Group 4 (control) received an infusion of saline solution during the first 30 minutes of occlusion. All cats breathed 100% oxygen throughout the occlusion and during 2 hours of reperfusion. Blood pressure, PaO2, and pH remained stable for 8 hours. PaO2 increased from an average base line level of 102 ± 15 (SD) torr to 520 ± 45 torr in Group 1, 450 ± 41 torr in Group 2, 480 ± 28 torr in Group 3, and 396 ± 151 torr in Group 4 during the administration of 100% oxygen. The average fluorocrit during occlusion was 6% in Groups 1, 2, and 3. The 24-hour mortality rate was 71% in Group 1, 43% in Group 2, 29% in Group 3, and 14% in Group 4; a midline shift and herniation were present after each fatal infarct. The survivors were sacrificed 10 days after the occlusion. There was a trend toward improvement of neurological function at sacrifice in Groups 2 and 3 compared with Groups 1 and 4. The infarct areas on coronal sections were 2.4 times larger in Group 1 (FDA only) than in Group 4 (control) (P<0.05). There was no significant difference in infarct size between Group 4 and Group 2 or 3. These results indicate that the administration of FDA and 100% oxygen after the onset of ischemia aggravated the effects of reperfusion in cats subjected to 6 hours of temporary MCA occlusion. The addition of mannitol and treatment before ischemia counteracted this effect, but did not improve the outcome in comparison with controls. (Neurosurgery 23:139-142, 1988)