Managing Postoperative Analgesic Failure: Tramadol Versus Morphine for Refractory Pain in the Post-Operative Recovery Unit

Objective. This study aimed to discover whether co-analgesia with tramadol or additional morphine was more effective for patients who still had severe pain despite being given 10mg intravenous morphine in the post-anesthesia care unit (PACU). Methods. All eligible patients were consented and recruited to the trial pre-operatively, but only a small subgroup - whose pain was not successfully controlled (pain score 6/10 or more) after receiving 10mg of morphine in the PACU-were then randomized to enter the trial and receive, in a double blinded fashion, the analgesic study drug; which consisted of either a further 10mg of morphine, or 100mg of tramadol, titrated intravenously to control their pain. The groups were compared as to: the time to readiness for discharge, the patient's pain scores over time, and the presence of side effects. Results. There was no statistically significant difference in any of the outcomes measured. The time to readiness for discharge from PACU was 119 minutes in the morphine group and 120 minutes in the tramadol group. However in approximately half the cases who entered the trial (i.e., where pain had not been controlled with the pre-enrollment baseline 10mg of morphine in PACU) neither a further 10mg of morphine nor 100mg of tramadol effectively relieved the patient's pain. Conclusions. We found no difference between additional morphine and co-analgesia with tramadol in this study. Patients who don't respond to reasonable doses of opioids in PACU are very likely to be unresponsive to further opioids, and other non-opioid analgesic techniques (such as regional anesthesia) should be considered early in this group of patients.