Hypoglycemia enhances bupivacaine-induced cardiotoxicity in the rat

The effect of blood glucose concentration on bupivacaine-induced cardiotoxicity was investigated in normoglycemic and hypoglycemic adult rats and compared to that of equipotent doses of lidocaine. The anesthetic agents were injected intraperitoneally into tracheostomized animals anesthetized with ketamine. ECG and direct blood pressure measurements were recorded continuously. Femoral arterial blood was used for determinations of glucose level, potassium concentration and base deficit values. Blood was drawn from the heart at the time of death for local anesthetic levels. In hypoglycemic animals, bupivacaine rapidly produced serious dysrhythmias leading to asystole. In normoglycemic rats, only ST-segment changes followed bupivacaine injection and death ensued from hypoxemia secondary to respiratory failure. With lidocaine, both hypoglycemic and normoglycemic rats died of hypoxemia following respiratory paralysis without antecedent dysrhythmias. Thus, hypoglycemia enhanced the cardiac effects of bupivacaine but not those of lidocaine.