Propofol-fentanyl versus isoflurane-fentanyl anesthesia for coronary artery bypass grafting: Effect on myocardial contractility and peripheral hemodynamics

To avoid intraoperative awareness and postoperative respiratory depression from high-dose opioid anesthesia, propofol (P), or isoflurane (I) has been combined with moderatedose opioid with varying results. However, the effects of both P and I on myocardial contractility and left ventricular afterload have not been completely quantified. The end-systolic pressure-diameter relationship (ESPDR) of the left ventricle (LV) is a reliable method to quantitatively assess LV contractility because it is relatively independent of changes in preload and incorporates afterload changes. The purpose of this study was to quantify the cardiodynamic effects of propofol-fentanyl (PF) anesthesia in comparison with isoflurane-fentanyl (IF) anesthesia in patients undergoing coronary artery bypass grafting (CABG). Thirty patients with normal or moderately impaired LV function (ejection fraction >=40% with LV end-diastolic pressure @?18 mmHg, no preoperative akinesia or dyskinesia) undergoing elective CABG were studied. After premedication with flunitrazepam, 2 mg orally, all patients were induced with thiopental, 1 mg/kg, fentanyl, 20 @mg/kg, and vecuronium, 0.1 mg/kg, and were ventilated with oxygen/air (F"1O"2 0.6). Anesthesia was maintained throughout the procedure with a zero-order intravenous (IV) continuous infusion of P, 3 mg/kg/h (PF group), or with isoflurane inhalation of 0.6% (IF group), supplemented by intermittent boluses (5 @mg/kg) of fentanyl (up to a total maintenance dose of 30 @mg/kg). After intubation, a cross-section of the LV was visualized by two-dimensional transesophageal echocardiography and an m-mode echocardiogram was obtained at the maximum anterior-posterior diameter. The radial artery pressure tracing and the ECG were simultaneously recorded with the M mode. Slope of ESPDR (Ees) and fractional shortening (FS) were measured before (T"0) and during P or I administration (T"1). A contemporary full hemodynamic profile using a pulmonary artery catheter was obtained at T"0 and T"1. Statistical significance was tested with a t test for paired data. No patient experienced awareness of any intraoperative events. There were no significant differences between T"0 and T"1 hemodynamic parameters in both PF and IF groups. No significant decrease of myocardial contractility, measured by Ees (15.3% with P vs. 11.1% with I), was seen at T"1, together with unchanged filling pressures (CVP and PCWP). Coronary perfusion pressure (CPP), as a myocardial perfusion index, was unmodified after both anesthetic drugs. In conclusion, low doses of P or I combined with moderate doses of fentanyl (up to 50 @mg/kg) give adequate levels of anesthesia and good hemodynamic stability. Slightly depressed contractility together with an unchanged CPP suggest a good myocardial oxygen balance (MDO"2/MVO"2) for both techniques.