[Postoperative pain therapy by transdermal fentanyl]

Abstract

Introduction: Several investigations have shown that constant rate infusions of opioids are highly effective in the provision of postoperative pain relief. However, such treatment require intravenous access, the availability of infusion pumps and adequate monitoring system. We have studied a transdermal fentanyl formulation (F-TTS, developed by ALZA Corporation, Palo Alto, USA) which should avoid these problems.

Methods: The study was performed in orthopaedic patients scheduled for hip arthroplasty. 40 patients were included consecutively in a double-blind parallel comparison of F-TTS (n = 20) and placebo (n = 20) patches. The patches were applied 0.5 hours prior to epidural anaesthesia and changed after 24 hours. F-TTS is designed to deliver fentanyl at the same rate of 75 micrograms/h. For 36 hours blood samples, pain scores, respiratory patterns and vital signs were collected frequently. Patients could have supplemental pethidine on demand (50 mg/2 h) if the pain relief was inadequate.

Results: Fentanyl blood concentrations increased (verum) during the 24 hours period (removal) and decreased slightly after that. At the end of the investigation (36 h) fentanyl concentration remained significantly elevated (about 60% of 24-hours value). F-TTS provided good postoperative pain relief although 11 patients (of 20) required supplemental pethidine. Patients with F-TTS, however had very little pethidine compared to patients with placebo. Two patients (one of each group) had to be eliminated from the study due to severe respiratory depression or inadequate pethidine requirement respectively. The incidence of other side effects such as nausea, vomiting and micturition difficulties were similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)