Influence of Cardiac Output on the Pharmacokinetics of Sufentanil in Anesthetized Pigs

Background: Sufentanil is used for general anesthesia and analgesia. The study aim was to determine the effect of pharmacologically induced changes in cardiac output on the pharmacokinetics of sufentanil in anesthetized pigs. Methods: Twenty-four pigs were randomly assigned to low, high, and control cardiac output groups. Cardiac output was decreased or increased from baseline by at least 40%, or maintained within +/- 10% of baseline, respectively. Sufentanil was administered as a bolus followed by a continuous infusion for 120 min. Timed arterial samples were drawn for sufentanil concentration measurements. Results: Data from 20 animals were analyzed. The cardiac outputs (means +/- SD) were 2.9 +/- 0.7, 5.4 +/- 0.7, and 9.6 +/- 1.6 l/min in the low, control, and high cardiac output groups, respectively. The parameters of the two-compartment pharmacokinetic model for these cardiac outputs were: CL1: 0.9, 1.2, and 1.7 l/min; CL2: 0.9, 3.1, and 6.9 l/min; V1: 1.6, 2.9, and 5.2 l; and V2: 27.5, 47.0, and 79.8 l, respectively. Simulated sufentanil doses to maintain a target plasma concentration of 0.5 ng/ml for 3 h were 99.5, 128.6, and 157.6 mu g for cardiac outputs of 3, 5, and 7 l/min, respectively. The context-sensitive half-times for these cardiac outputs increased from 3.1 to 19.9 and 25.9 min, respectively. Conclusions: Cardiac output influences the pharmacokinetics of sufentanil. Simulations suggest that in the case of increased cardiac output, the dose should be increased to avoid inadequate drug effect at the expense of prolonged recovery, whereas for low cardiac output the dose should be reduced, and a faster recovery may be expected.