Naloxone Continuous Infusion for Spinal Cord Protection in Endovascular Aortic Surgery Leads to Higher Opioid Administration and More Pain

Objective: Compare total perioperative opioid use in patients receiving naloxone continuousinfusion (NCI) for spinal cord ischemia prophylaxis, versus patients not receiving NCI, in endovascular aortic repair. Design: Single-center, retrospective cohort review. Setting: Academic medical center. Participants: Patients undergoing elective thoracic, thoracoabdominal, or abdominal aortic endovascular repair. Interventions: Patients were separated based on the use of naloxone continuous infusion as part of a spinal protection protocol. Primary endpoint was opioid requirements, in milligram morphine equivalents (MME), during the first 48 hours or during NCI. Secondary endpoints included: postoperative pain scores during the same interval; opioid requirements during hours 48 to 72; and pain scores during hours 48 to 72. Measurements and Main Results: Ninety-five procedures were included; 43 received naloxone continuous infusion and 52 patients were in the non-naloxone group. Opioid use from a linear mixed model was elevated across the entire continuum in the naloxone group (18 MMEs, 95% CI 13-24), with the greatest difference seen at the 24-to-48-hour interval (51 MMEs, 95% CI 26-75) after adjustment for age, incisions, and prehospital opioid use. In the naloxone group, pain score estimates were elevated at each postoperative interval of evaluation, with similar adjustment. Across the continuum this was 0.7 higher (95% CI 0.2-1.3); the zero-six-hour and six-to-12-hour intervals were 0.9 (95% CI 0.4-1.4) and 1.2 higher (95% CI 0.7-1.7). Conclusions: Patients receiving anloxone continuous infusion to prevent spinal cord ischemia required greater quantities of opioids and had higher postoperative pain, compared with patients not requiring naloxone.