ANGIOTENSIN-II ADMINISTRATION IMPROVES CEREBRAL BLOOD-FLOW IN CARDIOPULMONARY ARREST IN SWINE

Background and Purpose Cerebral blood flow during cardiopulmonary resu scitation is inadequate to meet cerebral metabolic demand. Adrenergic agonists improve cerebral blood flow, but clinical trials of increased doses in adults have not shown improved outcome from cardiac arrest. This may be due to adverse beta-agonist-mediated effects. The purpose of this study was to determine the effect of angiotensin II, a potent nonadrenergic vasopressor, on cerebral blood flow in cardiac arrest. M ethods Eleven immature swine were anesthetized and instrumented for re gional blood flow measurements with radiolabeled microspheres. A sagit tal sinus catheter was placed for blood gas determination. A blood flo w measurement was performed in normal sinus rhythm and ventricular fib rillation induced. After 10 minutes of ventricular fibrillation, cardi opulmonary resuscitation was begun and a blood flow measurement perfor med. Angiotensin 11 at a dose of 50 mug/kg was administered intravenou sly at 13 minutes of ventricular fibrillation. A blood flow measuremen t was performed and defibrillation attempted. A fourth blood flow meas urement was obtained if return of spontaneous circulation occurred. Re sults Total cerebral blood flow was 46.4 mL/min per 100 g in normal si nus rhythm. This fell to 6.9 mL/min per 100 g with cardiopulmonary res uscitation alone and rose to 30.8 mL/min per 100 g after the administr ation of angiotensin II. The improvement following angiotensin II was statistically different (P=.002). Cerebral blood flow further rose in the animals that had return of spontaneous circulation to 73.9 mL/min per 100 g. Conclusions Angiotensin II in a dose of 50 mug/kg significa ntly improves cerebral blood flow in this model of cardiac arrest.