Postoperative analgesia with parenteral opioids: Does continuous delivery utilizing a transdermal opioid preparation affect analgesic efficacy or patient safety?

Study Objectives: To compare, in patients who underwent major orthopedic surgical procedures, the efficacy of intravenous (IV) patient-controlled analgesia (PCA) with morphine combined with continuous administration of two doses of fentanyl or placebo via transdermal therapeutic system with fentanyl (TTSF) patches. Design: Randomized, double-blind, placebo-controlled study. Setting: University teaching hospital. Patients: 62 patients aged 18 to 65 years, presenting for elective orthopedic surgery and general anesthesia. Interventions: Patients were randomized to one of three groups: group 1 received two placebo patches: group 2 received a 20 cm² active patch delivering 50 μ/hr of fentanyl and a 30 cm² placebo patch; group 3 received a 30 cm² active patch delivering 75 μ/hr of fentanyl and a 20 cm² placebo patch. All patches were placed approximately two hours prior to induction of general anesthesia. General anesthesia was induced with thiopenial, intubation facilitated by the use of vecuronium or pancuronium, and anesthesia was maintained with isoflurane in an oxygen/nitrous oxide mixture (O₂/N₂O). Following surgery, IV morphine was provided using IV PCA with 1.5 mg of morphine with a 6-minute lockout and a 4-hour maximum dosage of 30 mg. Measurements and Main Results: The time and dosage of morphine administered was recorded. Vital signs, pain intensity at rest, level of sedation, and arterial oxygen saturation (SpO₂) were measured at intervals throughout the 72-hour study period and at 6 and 12 hours following patch removal. The presence of side effects was noted. Visual analog pain scores throughout the 72 hours of the study were not significantly different among groups. Patients receiving active TTSF required less IV PCA morphine at all time intervals. However, total opioid consumption was comparable among groups. The incidence of side effects was similar in all groups. Conclusions: There is no significant advantage to the routine use of continuous transdermal opioid delivery in patients receiving IV PCA after major orthopedic surgery.