Intrathecal Morphine in Major Abdominal and Thoracic Surgery: Observational Study

Introduction: Optimal control of acute postoperative pain in major surgery accelerates the recovery process, shortens hospital stays, and minimizes healthcare costs. Intrathecal morphine is a simple, safe, and reliable regional technique that provides prolonged analgesia, useful in a wide variety of procedures. Materials and Methods: A retrospective observational study was conducted on patients who underwent various major abdominal or thoracic surgical procedures and were administered intrathecal morphine between January 2018 and December 2021. The primary objective was to establish the safety of the technique in terms of the incidence of early and late respiratory depression, atelectasis, the need for respiratory support, and the possible association of these complications with the presence of respiratory pathology such as chronic obstructive pulmonary disease (COPD) or sleep apnea-hypopnea syndrome (SAHS), and obesity or smoking habit. Secondary objectives included recording the consumption of rescue intravenous (IV) morphine in the first 24 hours postoperatively, the incidence of PONV, and the incidence of late postoperative complications (at 90 days) such as pneumonia, readmission rates, and reoperation rates. Hospital stay and mortality were also recorded. Results: A total of 484 patients were included in the study. No patient experienced respiratory depression. Atelectasis, evidenced by chest X-ray, occurred in 2.07% of patients. Respiratory support with non-invasive mechanical ventilation (NIMV) or high-flow oxygen therapy (HFOT) was required by 1.86% of patients. 51% of patients required rescue IV morphine (average 6.98 mg), significantly higher in the thoracic and general surgery groups compared to urological surgery. The incidence of postoperative nausea and vomiting (PONV) was 30.37%. Regarding other secondary objectives, readmissions, reoperations, and mortality rates were significantly higher in patients undergoing urological and thoracic surgery compared to those undergoing general surgery. Conclusion: The administration of intrathecal morphine for the control of acute postoperative pain in major surgery can be considered a safe technique that fits perfectly within the set of measures for the multimodal approach to pain management in major abdominal and thoracic surgery.