CARDIOVASCULAR EFFECTS OF DIFFERENT INFUSION RATES OF SUFENTANIL IN PATIENTS UNDERGOING CORONARY SURGERY

Objective: Pharmacokinetics and haemodynamic effects of a total dose o f 15 mu g . kg(-1) sufentanil, an opioid anaesthetic agent, were studi ed in patients undergoing aortocoronary bypass surgery at three infusi on rates of 30 (group I), 5 (group II), and 2 (group III) mu g . kg(-1 ). min(-1) respectively. Results: Plasma concentrations of sufentanil could be optimally characterized by a linear biexponential pharmacokin etic model. Non-compartmental analyses indicated that there was no sig nificant difference in the values of clearance (11.6, 13.3, 14.3 ml . min(-1). kg(-1)), steady-state volume of distribution (0.220, 0.255 an d 0.3311 . kg(-1)) and mean residence time (18.8, 13.3 and 14.3 min) a mong the groups. The observed mean C-max values of 421 (group I), 125 (group II), and 53 (group III) ng . ml(-1) and observed mean AUC value s from 0 to 3 min were all consistent with the dosing regimens. There were large inter-individual variations in haemodynamic response. Compa red to plasma data, a delay in haemodynamic effects was found. Times t o reach peak haemodynamic effect ranged from 4.3 to 4.9 min for group I, from 4.6 to 6.1 min for group II, and from 9.9 to 11.3 for group II I. Except heart rate, peak haemodynamic effects in these study patient s generally ranged from 20.9% to 35.2%. Significant reductions in the area under the effect-time profiles of mean arterial blood pressure an d systemic vascular resistance were observed in group II and group III , but not in group I. Significant reductions in the area under the eff ect-time profiles of left ventricular stroke work index were observed in group III only. No effect on heart rate was found in any group. Con clusion: Our findings suggested that a slower infusion rate of sufenta nil at a dose of 15 mu g . kg(-1) tends to give a greater reduction in mean arterial blood pressure, systemic Vascular resistance, and left ventricular stroke work index than does a faster infusion rate.