Prolonged immobilization and controlled ventilation do not improve outcome after global brain ischemia in monkeys

This study is a therapeutic evaluation of prolonged immobilization and controlled intermittent positive-pressure ventilation (IPPV) after global brain ischemia (GBI) in pigtailed monkeys. Sixteen min of GBI was produced with a high-pressure neck cuff, while the lungs were being continuously ventilated. Normotension was restored within 2 min postischemia (PI). The control group of 13 monkeys was weaned from IPPV 4 to 6 h PI. The treatment group of 18 animals was paralyzed and ventilated with a 50:50 nitrous oxide-oxygen mixture for 48 h PI. Intensive care was maintained for 96 h PI. In the control group, 8 of 10 animals were awake at 96 h PI compared to 7 of 11 in the treatment group. Neurologic deficit scores for the survivors in the 2 groups were also not significantly different. Histologic examination supported this conclusion. Paralysis/IPPV for 48 h post-GBI with 50% N2O facilitates control of blood gases and blood pressure, but does not improve the neurologic outcome over that achieved with only 4 to 6 h controlled ventilation.