Milrinone is superior to epinephrine as treatment of myocardial depression due to ropivacaine in pigs.

Abstract

To determine whether milrinone is more effective than epinephrine in the resuscitation of ropivacaine induced cardiotoxicity in pigs. Arterial, pulmonary, and LVdP/dt catheters were placed in 12 anesthetized, intubated and mechanically ventilated pigs. They received ropivacaine iv to cardiovascular toxicity: 50% decrease in LVdP/dt, cardiac output and mean arterial pressure (MAP). Group I (n=6) was treated with 100 microg x kg(-1) milrinone iv, and Group II (n=6) received 0.5 mg epinephrine iv. Resuscitation was successful if cardiac output returned to baseline, and MAP reached 80% of baseline. After ropivacaine, MAP decreased from 88 +/- 7 to 49 +/- 8 mmHg (P < 0.05), CO decreased from 2.8 +/- 0.4 to 1.2 +/- 0.2 L x min(-1) (P < .05), HR decreased from 103 +/- 8 to 74 +/- 7 beats x min (P < 0.05) and LVdp/dt decreased from 1,950 +/- 130 to 755 +/- 125 mmHg (P < 0.05). The LV EDP increased from 5 +/- 1 to 8 +/- 1 mmHg (P < 0.05) and SVR from 2,317 to 3,000 +/- 120 dynes x sec(-1) x cm(-5). Electrocardiogram changes included increases in the QTU interval and QRS duration. In all animals, milrinone restored MAP, CO, SV, HR, and dP/dt to baseline and no animal developed arrhythmias. In contrast, epinephrine produced severe hypertension and tachycardia. There was no improvement in CO or SV, and SVR increased. Epinephrine caused A-V dissociation and ventricular arrhythmias in three animals. Milrinone, was more successful than epinephrine in resuscitating anesthetized pigs from ropivacaine-induced cardiovascular toxicity.