Starting intravenous morphine in the Postanesthesia Care Unit yielded better postoperative analgesia

Abstract

The administration of morphine intravenously in the Postanesthesia Care Unit (PACU) was practiced in many parts of the world, but not routinely done in Thailand. This prospective randomized controlled trial was performed to reassure Thai personnel that this practice was safe, to find the optimum dose of morphine for administration in the PACU, and to find the pain level at which patients needed no more analgesics. Eighty gynecological patients, ASA class I or II, were randomly allocated into two groups. Group A received morphine intramuscularly on demand for pain every 6 hours as is conventional. Group B received morphine intravenously by titration (with pain) in the PACU. On the ward, they received intramuscular morphine for pain as required. No patients had respiratory depression or oversedation. The amount of morphine needed in the PACU was related to and could be calculated from the pain score at which they first needed analgesics. Time to the first requirement of intramuscular morphine on the ward in group B was significantly longer than in group A. The amount of morphine and the number of analgesic requests on the ward in group B were significantly less than in group A. We concluded that giving morphine intravenously in the PACU was safe, effective and reduced postoperative analgesic requirement. The dose of morphine in the PACU could be calculated from the pain score at patients' first request for analgesics. Most patients declined additional analgesics when their pain was acceptable and tolerable.