HIGH-DOSE NALOXONE DOES NOT IMPROVE CEREBRAL OR MYOCARDIAL BLOOD-FLOWDURING CARDIOPULMONARY-RESUSCITATION IN PIGS

In a prospective, randomized, placebo-controlled, double-blind trial w e tested the hypothesis that naloxone given during cardiopulmonary res uscitation (CPR) enhances cerebral and myocardial blood flow. Twenty-o ne anesthetized, normoventilated pigs were instrumented for measuremen ts of right atrial and aortic pressures, and regional organ blood flow (radiolabeled microspheres). After 5 min of untreated fibrillatory ar rest, CPR was commenced using a pneumatic chest compressor/ventilator. With onset of CPR, an i.v. bolus of 40 mu g/kg b.w. of epinephrine wa s given, followed by an infusion of 0.4 mu g/kg per min. After 5 min o f CPR, either naloxone, 10 mg/kg b.w. (group N, n = 11) or normal sali ne (group S, n = 10) was given i.v. Prior to, and after 1, 15, and 30 min of CPR, hemodynamic and blood flow measurements were obtained. Aft er 30 min of CPR, mean arterial pressure was significantly higher in g roup N (26 +/- 5 vs. 13 +/- 3 mmHg, P < 0.05). Groups did not differ w ith respect to myocardial perfusion pressure or arterial blood gases a t any time during the observation period. Regional brain and heart blo od flows were not different between N and S at any point of measuremen t. We conclude that high-dose naloxone does not augment cerebral or my ocardial blood flow during prolonged closed-chest CPR. (C) 1997 Elsevi er Science Ireland Ltd.