Comparison of patient-controlled analgesia (PCA) with tramadol or morphine.

PURPOSE: To compared the clinical efficacy of tramadol and morphine using a patient-controlled analgesia (PCA) delivery system.

METHODS: In a prospective, randomized, double blind study, we evaluated 80 adult patients scheduled for elective hip or knee arthroplasty with general inhalational anesthesia. When patients complained of pain in the recovery room, patients were randomized to receive either tramadol or morphine by titration in 30 min to achieve analgesia (VAS < or =4). Equivalent volumes containing either 30 mg x ml(-1) tramadol or 1 mg x ml(-1) morphine were used for PCA with a lockout interval of 10 min. The patients were followed six-hourly for 48 hr for VAS, satisfaction rate, analgesic dose, and side effects.

RESULTS: Patients obtained adequate analgesia with either drug. More patients had very good satisfaction scores in the morphine group in the recovery room (43% vs. 23%, P<0.05) and at 24 hr (40% vs. 20%, P<0.05) than those in the tramadol group. More nausea was evident in the tramadol group (48% vs. 11% in recovery room and 28% vs. 12% in 24 hr, P<0.05) than in the morphine group. Vomiting was also more (28% vs. 5% in recovery room, 15% vs. 3% in 24 hr, P<0.05). Morphine produced more sleepiness (45% vs. 23% in recovery room, P<0.05 and 35% vs. 15% in 24 hr, P<0.05).

CONCLUSION: Tramadol PCA can provide effective analgesia following major orthopedic surgery provided sufficiently high doses are given for loading and by patient demand. However, the incidence of nausea/vomiting is also higher causing decreased satisfaction.