Oxygen-Fentanyl Anesthesia in Patients with Poor Left Ventricular Function

Seven patients with poor left ventricular function (LVF) defined as ejection fraction less than 0.3, left ventricular end-diastolic pressure equal to or greater than 20 ton, and at least one area of myocardial dyskinesia, and 12 patients with good LVF scheduled for aortocoronary bypass surgery were anesthetized with a loading dose of 30 μg/kg fentanyl followed by infusion of fentanyl at a rate of 0.3 μg/kg/min until the start of rewarming on cardiopulmonary bypass. Premedication consisted of 0.15 mg/kg of diazepam orally and 0.15 mg/kg of morphine and 0.4 mg of scopolamine intramuscularly. Hemodynamic studies were obtained before and after induction and also after intubation, skin incision, sternotomy, and aortic dissection. Blood samples were taken for fentanyl radioimmunoassay before induction of anesthesia and 5, 10, 20, and 30 min after induction, and every 30 min thereafter. There were no significant differences in plasma fentanyl concentrations in the two groups. However, all patients with good LVF, as compared with only three of seven patients with poor LVF, became hypertensive. A significant number of patients (P < 0.05) with poor LVF did not develop hypertension because they appeared to have insufficient myocardial reserve to allow them to increase cardiac index in the face of an increase in systemic vascular resistance. We conclude that the study patients with both poor and good LVF anesthetized with a fentanyl infusion technique show similar plasma concentrations of fentanyl. We further conclude that such patients respond differently during induction of anesthesia and initial surgery and that this difference is a function of myocardial reserve rather than depth of anesthesia.