Hemodynamic consequences of the combination of isoflurane anesthesia (1 MAC) and beta-adrenergic blockade in the dog.

Abstract

The hemodynamic response to the combination of isoflurane (1 MAC) and propranolol (0.5 mg/kg) was studied in 12 intact ventilated dogs following basal anesthesia with chloralose-urethane. When propranolol was administered during isoflurane anesthesia, stroke volume was maintained with a higher pulmonary capillary wedge pressure (3.2 plus or minus 0.7 mm Hg to 6.3 plus or minus 1.4 mm Hg), while systemic vascular resistance remained unchanged. When isoflurane was administered to the previously beta-adrenergically blocked dog, there were declines in systemic pressure and cardiac output (P smaller than 0.01) and in pulmonary arterial pressure and stroke volume (P smaller then 0.05), without change in systemic vascular resistance. When isoflurane was subsequently discontinued, these changes were reversed, and in addition, systemic vascular resistance increased (P smaller than 0.05). These data indicate that isoflurane has pharmacologic properties compatible with a peripheral beta-adrenergic stimulating action.