Résumé : The combination of phosphodiesterase inhibitors and adrenergic agents represents an interesting option to increase cardiac output in acute circulatory failure. We investigated the effects of the combination of amrinone with norepinephrine in an experimental model of endotoxin shock, with particular reference to the hemodynamic profile, concurrent fluid administration, and ultimate survival. In 20 dogs (28 ± 5 kg) anesthetized with pentobarbital and mechanically ventilated, 3 mg/kg of Escherichia coli endotoxin were administered intravenously. After 30 minutes, saline was administered at a rate adjusted to maintain pulmonary artery balloon-occluded pressure at baseline level. Sixty minutes after endotoxin administration, dogs were randomized to receive norepinephrine, 0.1 μg/kg/min, either alone or in association with 40 gg/kg/min of amrinone. At the end of the four-hour experiment, the dog was returned to its cage until the next day. The combination of amrinone and norepinephrine resulted in a lesser increase in arterial pressure than norepinephrine alone, but markedly increased cardiac output (by 50%) and stroke volume. These differences were statistically significant (both P < .025). Total amount of fluids infused was 54 ± 10 mL/kg in the amrinone-treated dogs and 48 ± 11 mL/kg in the other dogs (difference not significant). Eight of the amrinone-treated dogs but only four of the other dogs survived until the next morning (P < .05). These results therefore indicate that the addition of amrinone to norepinephrine can markedly increase cardiac output and improve survival in this model of canine endotoxin shock. © 1989.