The effects of an insulin-glucose-potassium (IGK) pretreatment on the bupivacaine cardiotoxicity

Background: The purpose of this study is to evaluate the effect of an IGK pretreatment on the cardiotoxicity of bupivacaine. Methods: Twenty-one anesthetized mongrel dogs were randomly divided into the following three groups: the control group (CG, n = 7), the treatment group (TG, n = 7) and the pretreatment group (PTG, n = 7). For the 30 min of pretreatment period, CG and TG received normal saline, while PTG received an IV bolus of insulin 2 U/kg, followed by an IGK infusion (2 U/kg/hr of insulin, 0.5-1.5 g/kg/hr of glucose, 1-2 mEq/kg/hr of KCl). The bupivacaine infusion was started at the rate of 0.5 mg/kg/min in all groups after the pretreatment period. CG received normal saline only. In TG, insulin (2 U/kg) was injected simultaneously with bupivacaine infusion, followed by the IGK infusion as with PTG. The hemodynamic variables and the time duration to reach the mean arterial pressure (MAP) of 60 mmHg were compared. Results: The bupivacaine infusion decreased the cardiac index, MAP, and heart rate in all three groups. Although insulin concentration was higher in TG than in PTG during bupivacaine infusion, the hemodynamic variables in PTG decreased at the slowest rate. The time taken to reach MAP of 60 mmHg in PTG, TG, and CG was 51.4 ± 8.5, 36.4 ± 9.6, and 27.1 ± 8.7 min, respectively (P < 0.05). Conclusions: IGK delays the bupivacaine-induced cardiac depression. However, a pretreatment with IGK is more effective in delaying the bupivacaine-induced hypotension than simultaneous administration, regardless of insulin concentration.