Analgesic Efficacy and Safety of Intrathecal Morphine in Surgical Patients: A Narrative Review.

It is well established that intrathecal morphine (ITM) provides prolonged postoperative analgesia and reduces systemic opioid requirements across a wide range of surgical procedures. Although extensive evidence supports the efficacy and safety of ITM, concern for delayed respiratory depression persists. Additionally, there is no standard approach for ITM dosing or postprocedural monitoring practices across institutions or medical societies, leading to wide variability that further contributes to inconsistent adoption. In this narrative review, we synthesize contemporary evidence on the pharmacology, analgesic efficacy, and risk profile of ITM and evaluate how current evidence aligns with existing postprocedural monitoring recommendations. A structured literature review identified clinical trials, observational studies, systematic reviews, and practice guidelines published within the past 20 years that evaluated perioperative ITM use. Across surgical populations, ITM is associated with reductions in postoperative pain scores and systemic opioid consumption at contemporary doses. At these doses, the incidence of respiratory depression was low and comparable to that observed with intravenous opioids. Reported respiratory events were strongly associated with patient-specific risk factors. Overall, current evidence supports the use of ITM as an effective analgesic modality with an acceptable safety profile. These findings support a risk-stratified approach to postprocedural monitoring that accounts for patient comorbidities and the ITM dose administered.