Intrathecal Opioids for Non-Emergent Cesarian Section In Latin American Women: A Retrospective Cohort Study (Re-Mice Study)

Abstract

Background: Common use of intrathecal opioids for cesarean sections has been limited due to reported adverse events, despite their significant role in postoperative analgesia. It has been suggested that a dose reduction could potentially reduce adverse effects without affecting efficacy of postoperative analgesia. Objectives: The aim of this study was to identify the most frequently used intrathecal opioid doses by Latin-American women who underwent non-emergent cesarean sections at a reference center and reported adverse events during the first 6, 12, and 24 hours after administration. Methods: We retrospectively analyzed a cohort of women that underwent non-emergent cesarean sections under spinal anesthesia during the period of January 2011 to June 2014. The associations between different doses of intrathecal morphine (≤50; 51-75; 76-100 and 101-150 mcg) with and without intrathecal fentanyl (20-25 mcg) and pruritus, postoperative nausea/vomiting, and respiratory depression probabilities were assessed using a uni-bivariate proportional hazards model and a multivariate logistic model. Results: Out of 1,405 patients treated with any type of intrathecal opioid for cesarean section, 1,314 (93.5%) received intrathecal morphine. We detected a significant association between pruritus probability and intrathecal morphine dose during the first 6 postoperative hours. There was no correlation between postoperative nausea/vomiting occurrence and increasing intrathecal morphine doses. Conclusions: Intrathecal morphine 50 to 150 mcg and intrathecal fentanyl 20 to 25 mcg are effective and safe. During the first 6 postoperative hours, pruritus, but not postoperative nausea/vomiting, shows a significant correlation with intrathecal morphine doses of 75 to 100 mcg.