ADMINISTRATION OF PROPOFOL BY TARGET-CONTROLLED INFUSION IN PATIENTS UNDERGOING CORONARY-ARTERY SURGERY

Objectives: To study the predictive performance of a target-controlled infusion (TCI) system of propofol in patients undergoing coronary art ery bypass graft (CABG) surgery, using a referenced pharmacokinetic se t derived from healthy patients. Also, to determine the propofol conce ntrations required for clinically acceptable induction and maintenance of anesthesia when combined with midazolam as premedication and a con tinuous alfentanil infusion and to study the hemodynamic stability of this technique. Design: Prospective noncomparative study analysis. Set ting: Operating room at a university hospital. Participants: Twenty-on e patients with good left ventricular function undergoing coronary art ery surgery. Interventions: Patients were anesthetized using a continu ous infusion of alfentanil (mean infusion rate: 1 mu g/kg/min) and pro pofol administered by TCI. Measurements and Main Results: The predicti ve performance of the TCI system (212 arterial samples) was measured a t specified time paints before, during, and after bypass. The TCI syst em underestimated the measured blood propofol concentrations with a bi as of +21.2% and +9.6% during the prebypass and the bypass periods, re spectively. The predictive inaccuracy, expressed by the median absolut e prediction error, was 23% and 18.5%, respectively. Mean target propo fol concentrations required to induce and maintain anesthesia before b ypass were 0.92 mu g/mL and 3.64 mu g/mL, respectively. In the period during and after bypass, the mean target concentration required to mai ntain anesthesia was 2.22 mu g/mL. The administration of propofol by T CI was still associated with some short episodes of hemodynamic instab ility that were easily controlled by adjusting the target concentratio n in the majority of the patients. Therefore, the overall quality and ease of control of anesthesia were considered as being good or adequat e. Conclusions: In this group of patients undergoing CABG surgery, the TCI system used underestimated the measured propofol concentrations. However, the predictive performance of the selected mean pharmacokinet ic parameters derived from healthy patients was acceptable during the whole surgical procedure. Copyright (C) 1996 by W.B. Saunders Company