Effect of postcirculatory-arrest life-support on neurological recovery in monkeys

The existence of treatable postischemic (PI) changes which influence neurological outcome has been documented by this group before. A global brain ischemia model without cardiac arrest was developed in monkeys. It includes high-pressure neck tourniquet inflation plus hypotension for a reproducible ischemic insult; survival with reproducible neurological deficit (ND) under continuous PI life-support for 7 days with control of extracranial variables; and new ND and histopathological damage scoring systems.Hypoxemia, hypercarbia, hypotension, uremia, sepsis, and other extracranial complications PI in 50 unsatisfactory experiments led to immediate worsening in ND and brain death (ND = 100%) in most of these monkeys. In contrast, all monkeys with the same initial insult, with life-support according to protocol, survived with a 7 day ND of 60% or less.In 46 experiments of seven treatment groups, after 16 or 18 min ischemia, life support was according to protocol for 7 days. The control 1 protocol (spontaneous breathing when feasible) resulted in a mean 7-day ND score of 53% (including quadriplegia). Immobilization with pancuronium and controlled ventilation ameliorated deficit to an ND score of 19% (P < 0.05) (including quadriparesis); this became control 2 protocol. Immobilization resulted in less neuronal damage in the neocortex. Severe repetitive hypertension worsened ND to 46%, versus 19% in controls (P < 0.05). In separate series, neither heparinization over 72 hours PI, nor hemodilution to hematocrit 25% with dextran 40, changed final ND significantly from that of their control groups. Histopathological damage scores correlated with ND scores.