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

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 (O2), and small boli of alfentanil or sufentanil. Preoperatively, the first group (F) received a transdermal therapeutic system fentanyl patch (75 micrograms/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 O2 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.