Postoperative analgesia and plasma levels after transdermal fentanyl for orthopedic surgery: Double-blind comparison with placebo

Abstract

Study Objective: To determine whether transdermal fentanyl can provide a significant component of postoperative analgesia. Design: Randomized, double-blind study. Setting: Inpatient surgery in a university hospital. Patients: 40 adult patients scheduled for orthopedic surgery with general anesthesia. Interventions: 20 patients in each group had general anesthesia with propofol, isoflurane in nitrous oxide and oxygen (O 2), and small boli of alfentanil or sufentanil. Preoperatively, the first group (F) received a transdermal therapeutic system fentanyl patch (75 μg/hr) for 72 hours, and the second group (P) received a placebo patch. Morphine was given postoperatively according to clinical necessity. Measurements and Main Results: Morphine consumption, pain visual analog scale, and eventual sedation were assessed, as well as respiratory rate and blood pressure. Plasma fentanyl concentrations were determined. Only 11 Group F patients needed morphine compared with 19 Group P patients, and mean morphine dose was significantly lower in Group F. One Group F patient had decreased O 2 saturation and intense sedation, necessitating administration of naloxone. The mean maximum plasma fentanyl concentration in Group F was 1.63 ng/ml. Conclusion: Efficacy of transdermal fentanyl for postoperative pain relief is shown, but intense respiratory depression is sometimes seen.