A comparison of combined amrinone and glucagon therapy to glucagon alone for cardiovascular depression associated with propranolol toxicity in a canine model.

Multiple inotropic agents may be required to improve hypotension associated with beta-blocker toxicity. This study compared combined amrinone and glucagon therapy to glucagon alone and saline control for the treatment of propranolol-induced cardiovascular depression in a canine model. Six animals were pretreated with 10 mg/kg of propranolol intravenously (i.v.), which resulted in significant depression in heart rate (HR), cardiac output (CO), mean arterial pressure (MAP), and maximal left ventricular change in pressure over time (dP/dt max) (P < .0001). Each canine received i.v. amrinone (4 mg/kg) plus glucagon (20 micrograms/kg) therapy during a 2-minute period after propranolol infusion was completed. Cardiovascular parameters were monitored at 1, 6, 11, 21, and 31 minutes after treatment was rendered. Results were compared with those of a previous study, consisting of six animals that received glucagon therapy alone (20 mg/kg) and six controls (normal saline only) in an identical protocol. The addition of i.v. amrinone to glucagon therapy did not increase significantly, HR, CO, stroke volume, or dP/dt max compared with glucagon alone. Total systemic peripheral resistance was reduced significantly during 31 minutes of observation after the administration of combined therapy compared with the control; glucagon alone also reduced systemic peripheral resistance at 1 and 6 minutes. At all time periods except 1 minute of observation there was a significant reduction in MAP when comparing combined therapy with that of glucagon therapy alone. In this model, the addition of amrinone to glucagon therapy seems to have a detrimental effect on the ability of glucagon to increase MAP resulting from propranolol toxicity.