Comparative hemodynamic effects of propofol and thiamylal sodium during anesthetic induction for myocardial revascularization.

The safety and efficacy of propofol, a new intravenous anesthetic agent, have been demonstrated in healthy patients. Twenty-one patients, ASA III-IV, undergoing elective myocardial revascularization, were randomly chosen to receive either propofol, 2.5 mg/kg, or thiamylal, 4 mg/kg. for the induction of anesthesia. Hemodynamics were recorded at one and three minutes after drug administration during spontaneous respiration. After the addition of halothane and pancuronium with controlled ventilation, measurements were made immediately prior to and one minute after intubation. Five patients were dropped from the study, four due to airway problems and one due to severe hypotension following an induction dose of propofol. Statistics were done using data from the remaining 16 patients, eight in each group. Administration of propofol resulted in significant decreases in mean arterial pressure (MAP), systemic vascular resistance (SVR), and left ventricular stroke work index (LVSWI); as well as an increase in heart rate (HR). These changes were further accentuated by the addition of halothane and pancuronium prior to intubation. Patients in the thiamylal group experienced no significant hemodynamic changes until halothane and pancuronium were added and controlled ventilation was instituted. With these additions, the thiamylal group showed significant decreases in MAP and LVSWI immediately prior to intubation. Both groups experienced significant increases in HR following intubation, but no evidence of myocardial ischemia was seen in either group. All other parameters returned toward control values. Propofol appeared to be safe and effective for the induction of anesthesia in this group of patients, although its hemodynamic effects were greater than those of thiamylal.