Comparison of the effects of amrinone, milrinone and olprinone in reversing bupivacaine-induced cardiovascular depression

Background: Increasing evidence indicates that amrinone, a phosphodiesterase fraction III (PDE-III) inhibitor, has relative efficacy as an initial treatment for cardiovascular depression after bupivacaine in an experimental setting. This study was performed to compare the cardiovascular effects of the other new PDE-III inhibitors, milrinone and olprinone, with those of amrinone in reversing bupivacaine-induced cardiovascular depression. Methods: In sevoflurane-anaesthetized dogs, bupivacaine was infused intravenously at 1 mg.kg(-1).min(-1) until mean arterial pressure fell to 60 mmHg or less. The dogs received either amrinone (2 mg kg(-1)), milrinone (0.2 mg.kg(-1)), olprinone (0.12 mg kg(-l)) or 0.9% saline (0.5 ml.kg(-1)). Results: Amrinone, milrinone and olprinone improved left ventricular systolic and diastolic function, resulting in an increase in cardiac index. The most significant difference observed among the three drugs was the change in heart rate (HR) after treatment. Milrinone significantly increased HR, but olprinone did not. Conclusion: Milrinone and olprinone are as effective as amrinone in reversing bupivacaine-induced cardiovascular depression.