ABSTRACT
OBJECTIVES: To analyze the effect of isoflurane on myocardial metabolism and coronary hemodynamics during the reheating phase after heart surgery. PATIENTS AND METHODS: Sixteen patients (12 women and 4 men), with cardiac output greater than 0.5 undergoing aortic and/or mitral valve surgery, were studied prospectively. A retrograde thermodilution catheter was placed in the heart and a Swan-Ganz catheter was inserted in the pulmonary artery to determine coronary blood flow and pulmonary wedge pressure, respectively, as well as myocardial and systemic parameters. After surgery, and with hemodynamic variables stable and rectal temperature at 34 +/- 0.5 degrees C, 0.4% isoflurane was administered at the end of expiration. Variables were recorded before administering isoflurane and 20 minutes afterwards. RESULTS: Isoflurane administration decreased coronary perfusion pressure, coronary vascular resistance, regional myocardial oxygen consumption and myocardial oxygen output. Increases in coronary oxygen saturation and in large coronary vein saturation were also observed. No patient experienced significant changes in ST segment, enzymes or decreased clearance of lactic acid. CONCLUSIONS: Administering 0.4% isoflurane at the end of expiration effected coronary vasodilation without altering oxygenation or myocardial metabolism. Moreover, no electrocardiographic, enzymatic or metabolic signs of myocardial ischemia were observed.
Subject(s)
Anesthesia, Inhalation , Anesthetics, Inhalation , Coronary Circulation/physiology , Homeostasis/drug effects , Hypothermia, Induced , Isoflurane , Adult , Aged , Cardiac Surgical Procedures , Coronary Circulation/drug effects , Female , Hemodynamics/drug effects , Hemodynamics/physiology , Humans , Male , Middle AgedABSTRACT
OBJECTIVE: To compare isoflurane and propofol as the principal sedatives in ventilated patients after cardiac surgery with extracorporeal circulation (ECC). PATIENTS AND METHODS: Forty consecutive, randomized patients undergoing cardiac surgery with ECC were studied prospectively. Patients were assigned to receive either isoflurane or propofol. Variables recorded were level of sedation, adaptation to the respirator and hemodynamic stability. RESULTS: Each group included 20 patients. The mean dose of isoflurane was 0.39% +/- 0.06% of end-tidal concentration. The mean propofol dose was 2.11 +/- 0.55 mg/kg/h. Statistically significant differences were found for stabilization of sedation time (4 min +/- 1.17 for isoflurane and 11.7 min +/- 4.78 for propofol) and time to endotracheal extubation (56.2 min +/- 20.47 for isoflurane and 72.65 min +/- 30.90 for propofol), number of times dosage had to be changed (2.20 +/- 0.89 with isoflurane and 7.05 +/- 2.58 with propofol) and time of administration had to be interrupted (8.45 min +/- 8.73 with propofol and 0.75 min +/- 1.94 with isoflurane). CONCLUSIONS: In comparison with propofol, isoflurane offers advantages of rapid stabilization of sedation, ease of use and shorter time to endotracheal extubation.
