Cardiovascular responses to propofol and etomidate in long-term instrumented rhesus monkeys (Macaca mulatta)

Background and Purpose: Cardiac and arterial responses to prescribed doses of propofol and etomidate in rhesus monkeys were compared. Methods: Intravenously administered induction doses of propofol (2 mg/kg of body weight) or etomidate (1 mg/kg) followed by continuous intravenous inf usions of propofol (200 mu g/kg/min) or etomidate (100 mu g/kg/min) were ad ministered. Left ventricular and right atrial access catheters were implant ed for long-term use, along with a transit-time flow probe on the ascending aorta, and pericardial electrocardiogram leads. A dual sensor 3-F microman ometer was used to measure left ventricular pressure and aortic pressure, a nd an active redirectional transit-time probe measured aortic flow. Noorder graaf's four-element model was used to estimate total peripheral resistance and systemic arterial compliance. Results: Significant (P < 0.01) decreases in mean arterial pressure, heart rate, and myocardial contractility were accompanied by an increase in syste mic arterial compliance associated with propofol and etomidate, Only minima l changes in left ventricular diastolic pressure, cardiac output, stroke vo lume, and total peripheral resistance were found for both drugs. The change s associated with propofol are comparable to results in human beings, where as the changes associated with etomidate did not agree with results of publ ished human studies. Conclusion: The significant cardiovascular alterations associated with both agents were attributed to reductions in heart rate, although the possibili ty exists that negative inotropic effects may have had a role.