Resuscitation from bupivacaine-induced asystole in rats: comparison of different cardioactive drugs.

The objective of this study was to compare the success of resuscitation attempts with different cardioactive drugs after bupivacaine-induced asystole. Saline, amrinone (1 mg/kg), dopamine (5 micrograms/kg), norepinephrine (2 micrograms/kg), epinephrine (10 micrograms/kg), or isoproterenol (1 microgram/kg) were tested. Sixty rats assigned to six treatment groups (n = 10/group) were lightly anesthetized (0.5% halothane, 70% N2O), paralyzed (doxacurium), and given bupivacaine intravenously at 4 mg.kg-1.min-1 until asystole. Five seconds later up to three treatment drug doses were given at 30-s intervals. Then external cardiac massage was instituted as needed. Spontaneous heartbeat was restored in all animals given norepinephrine or epinephrine. It was not restored in one saline-treated, one dopamine-treated, one isoproterenol-treated, and three amrinone-treated animals. The highest (best) arbitrary scores for overall resuscitation success were achieved with norepinephrine and the lowest with amrinone (P < 0.05). The incidence of ventricular arrhythmias after resuscitation was significantly higher (P < 0.05) in epinephrine- and isoproterenol-treated animals versus other animals. Cardiac rhythm disturbance disappeared within 20 min after successful resuscitation with norepinephrine. Amrinone was no more effective than saline in treating bupivacaine-induced asystole. A drug such as norepinephrine, which has both cardiostimulator (beta 1-receptor agonist) and peripheral vasoconstrictor (alpha 1-receptor agonist) activity, may be the drug of choice for treating asystole induced by bupivacaine.