Effectiveness of intrathecal dexmedetomidine versus fentanyl as additives to hyperbaric bupivacaine on postoperative analgesia in patients undergoing Cesarean section: a systematic review and meta-analysis.

OBJECTIVE

This review compared the effectiveness of intrathecal dexmedetomidine with fentanyl as additives to hyperbaric bupivacaine for providing postoperative analgesia after Cesarean section.

INTRODUCTION

There are limited treatment options for pain following Cesarean section due to potential parturient and neonatal side effects. Intrathecal dexmedetomidine has emerged as an alternative to intrathecal opioids for prolonging postoperative analgesia, but its effectiveness requires further investigation.

ELIGIBILITY CRITERIA: The review evaluated studies of patients who underwent Cesarean section under spinal anesthesia where dexmedetomidine and fentanyl were compared as intrathecal additives to hyperbaric bupivacaine. The outcomes were postoperative pain scores in the first 24 hours, duration of analgesia, duration of motor block, and the incidence of side effects. Randomized controlled trials, non-randomized controlled trials, and prospective cohort studies were considered.

METHODS

PubMed, Cochrane Central Register of Controlled Trials, Scopus, and Embase were searched in September 2023 and May 2024. ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, and Google Scholar were searched for gray literature. Study selection, critical appraisal, data extraction, and data synthesis were conducted using the JBI methodology for systematic reviews of effectiveness. Assessment of the certainty in findings was conducted using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Fifteen studies (13 RCTs and 2 non-randomized, prospective cohort studies) with 1098 participants were included. The overall risk of bias was moderate. There was low to moderate certainty that dexmedetomidine results in lower pain scores up to 6 hours postoperatively, with only the difference at 4 hours greater than the minimum clinical important difference of 1 point on a numeric pain rating scale (2 RCTs, 100 participants; mean difference [MD] 1.26 points lower, 95% CI 1.78 to 0.74). There was low certainty that dexmedetomidine prolongs the duration of analgesia (8 RCTs, 578 participants; MD 93.3 minutes, 95% CI 62.40 to 124.19). There was very low certainty that dexmedetomidine prolongs the duration of motor block (8 RCTs, 502 participants; MD 29.68 minutes, 95% CI 0.96 to 58.40). There was low certainty that dexmedetomidine increases the risk of hypotension (10 RCTs, 688 participants; absolute difference of 2% increase in risk, 95% CI 6% decrease to 11% increase) and bradycardia (8 RCTs, 558 participants; absolute difference of 2% increase in risk, 95% CI 2% decrease to 8% increase). There was moderate certainty that dexmedetomidine decreases the risk of nausea and vomiting (8 RCTs, 558 participants; absolute difference of 7% decrease in risk, 95% CI 11% to 0% decrease); pruritus (7 RCTs, 442 participants; absolute difference of 11% decrease in risk, 95% CI 11% to 9% decrease); and shivering (5 RCTs, 390 participants; absolute difference of 8% decrease in risk, 95% CI 9% decrease to 3% decrease).

CONCLUSIONS

Dexmedetomidine probably results in a meaningfully lower pain score, limited to the fourth hour postoperatively, and may result in a longer duration of analgesia. Dexmedetomidine probably results in lower incidence of nausea and vomiting, pruritus, and shivering. Dexmedetomidine may increase the incidence of hypotension and bradycardia. It is uncertain whether dexmedetomidine results in a longer duration of motor block.