Analgesic Outcomes in Opioid Use Disorder Patients Receiving Spinal Anesthesia with or without Intrathecal Clonidine for Cesarean Delivery: A Retrospective Investigation.

Background: Intrathecal (IT) clonidine has been observed to reduce 24-hour opioid requirements and time to first analgesic request after cesarean delivery, but has not been specifically studied in patients with opioid use disorder (OUD). Methods: Patients with OUD undergoing cesarean delivery under spinal or combined spinal-epidural (CSE) anesthesia at our institution from 2011 to 2020 were identified, and only patients with OUD were included in this study. Subjects that received IT clonidine were compared to a control group that did not receive IT clonidine to observe potential differences in analgesic outcomes (24-hour opioid requirements, pain scores and time to first post-operative pain medication) or side-effects (hypotension, vasopressor dosing and bradycardia). Results: A total of 160 patients were included (clonidine n = 22, controls n = 138). For the clonidine group, the median IT clonidine dose was 30µg. Clonidine group patients were observed to have greater dose of IT bupivacaine (12 vs 12.75mg; p = 0.01) and IT morphine (100 vs 200µg; p < 0.001). The clonidine group was also observed to have greater incidence of intraoperative hypotension (20% vs 45%; p = 0.01) and maximum phenylephrine dose (50 vs 57.5 µg/min; p < 0.001). The time to first analgesic request (minutes) after surgery was significantly longer for the clonidine group (153.5 vs 207 min; p < 0.001). The average oral oxycodone equivalents taken per 24 hours of hospital admission were significantly less in the clonidine group (82.36 vs 41.67mg; p < 0.001), and the clonidine group also had significantly less oxycodone equivalents taken for each post-operative day. Conclusion: IT clonidine was observed to result in reduced 24-hour opioid consumption in patients with OUD and may be useful as part of a multimodal analgesic regimen. The incidence of hypotension and vasopressor doses were greater in patients receiving IT clonidine, and this should be anticipated if IT clonidine is being administered.