RESUMO
OBJECTIVE: To compare enoximone with epinephrine as treatments for the cardiotoxic effects of protamine sulfate. STUDY DESIGN: Prospective randomized study. ANIMAL POPULATION: 12 healthy cross-bred dogs weighing 23 +/- 4 kg. METHODS: The dogs were anesthetized with xylazine and ketamine to allow instrumentation. Femoral arterial and venous catheters were inserted for pressure monitoring and to allow drug infusion. A thermodilution catheter mounted with a fast response thermistor was inserted into the pulmonary artery via the jugular vein to measure cardiac output and right ventricular volumes. Heparin 300 units/kg followed by protamine 4.5 mg/kg were administered 45 minutes after the xylazine/ketamine. Four animals were not treated (controls), four received enoximone, and four were given epinephrine. Cardiopulmonary parameters were monitored for a period of 30 minutes. RESULTS: Cardiac index was 104 +/- 15 mL/kg/min in the enoximone group, 72 +/- 13 mL/kg/min in the epinephrine group, and 63 +/- 10 mL/kg/min in the control group (P < .05 enoximone versus control and epinephrine). Right ventricular end systolic volume was 18 +/- 3, 27 +/- 4, and 29 +/- 6 mL in the enoximone, epinephrine, and control groups (P < .05 enoximone versus control and epinephrine). There were no differences in mean arterial pressure or pulmonary and systemic vascular resistance between the groups. CONCLUSION AND CLINICAL RELEVANCE: In this study, enoximone was more effective than epinephrine at reversing the hemodynamic changes associated with protamine sulfate administration.