Postoperative intravenous morphine titration

Abstract

Relief of acute pain during the immediate postoperative period is an important task for anaesthetists. Morphine is widely used to control moderate-to-severe postoperative pain and the use of small i.v. boluses of morphine in the post-anaesthesia care unit allows a rapid titration of the dose needed for adequate pain relief. The essential principle of a titration regimen must be to adapt the morphine dose to the pain level. Although morphine would not appear to be the most appropriate choice for achieving rapid pain relief, this is the sole opioid assessed in many studies of immediate postoperative pain management using titration. More than 90% of the patients have pain relief using a protocol of morphine titration and the mean dose required to obtain pain relief is 12 (7) mg, after a median of four boluses. Sedation is frequent during i.v. morphine titration and should be considered as a morphine-related adverse event and not evidence of pain relief. The incidence of ventilatory depression is very low when the criteria to limit the dose of i.v. morphine are enforced. Morphine titration can be used with caution in elderly patients, in children, or in obese patients. In practice, i.v. morphine titration allows the physician to meet the needs of individual patients rapidly and limits the risk of overdose making this method the first step in postoperative pain management.