Insulin versus vasopressin and epinephrine to treat beta-blocker toxicity.

OBJECTIVE

We compared insulin and glucose (IN/G) to vasopressin plus epinephrine (V/E) in a pig model of beta-blocker toxicity. Primary outcome was survival over four hours.

METHODS

Ten pigs received a 0.5 mg/kg bolus of propranolol IV followed by a continuous infusion. At the point of toxicity 20 ml/kg normal saline was rapidly infused and the propranolol drip continued at 0.125 mg/kg/min over four hours of resuscitation. Each pig was randomized to either IN/G or V/E. The V/E group began with epinephrine at 10 mcg/kg/min titrated up by 10 mcg/kg/min every 10 min to 50 mcg/kg/min or until baseline was obtained. Simultaneously, these pigs received vasopressin at 0.0028 units/kg/min, titrated upwards every 10 min to 0.014 units/kg/min or until baseline was obtained. The IN/G group began with a 2 units/kg/hr drip and increased by 2 units every 10 minutes to 10 units/kg/hr, or until baseline hemodynamics were obtained. CO, SVR, systolic blood pressure, HR, MAP, glucose, and potassium were monitored. Glucose was given for values <60 mg/dl.

RESULTS

The study was terminated early due to marked survival differences after five pigs were entered in each group. All IN/G group pigs survived four hours. All V/E group pigs died within 90 min. CO in the IN/G group increased throughout the four hours, rising above pre-propranolol levels, while MAP, SBP, and SVR all trended slightly downward. CO in the V/E group dropped until death, while MAP, SBP, and SVR rose precipitously until 30-60 minutes when these dropped abruptly until death. Glucose was required in the IN/G group.

CONCLUSION

In this swine model, IN/G is superior to V/E to treat beta-blocker toxicity. IN/G has marked inotropic properties while the vasopressor effects of V/E depress CO and contribute to death. Increasing SVR in this condition is detrimental to survival.