Comparison of the Analgesic Efficacy of a Single Dose of Epidural Dexmedetomidine versus Fentanyl as an Adjuvant to Bupivacaine in Abdominal Surgery

BACKGROUND: Fentanyl as an epidural additive act on spinal opioid receptors, while dexmedetomidine has selective alpha-2 receptor agonist action enhancing analgesic effects. AIMS: We aimed to compare the postoperative analgesic efficacy of single doses of dexmedetomidine against fentanyl as epidural adjuvant to 0.125% bupivacaine. SETTINGS AND DESIGN: A prospective, randomized, controlled, double-blind trial was conducted in a tertiary care teaching institute. PATIENTS AND METHODS: Forty-six patients undergoing abdominal surgery under general anesthesia with epidural analgesia were allocated into two groups to receive postoperative analgesia with single doses of 10 mL 0.125% bupivacaine with the addition of dexmedetomidine 0.5 μg.kg-1 (Group D) or fentanyl 0.5 μg.kg-1 (Group F). The primary outcome was the duration of postoperative analgesia between the two groups. The secondary outcomes were hemodynamic variations, vasopressor need, and motor blockade. STATISTICAL ANALYSIS: Chi-square test for static parameters and Student's t-test or Mann–Whitney test for continuous variables were used for analysis. RESULTS: The duration of analgesia was longer in Group D (5.0 ± 2.0 h) versus Group F (2.9 ± 1.4 h), Sixteen patients in Group D versus seven patients in Group F needed vasopressors after the bolus to maintain the blood pressure (BP) within 20% of prebolus value (P = 0.018). Heart rate and mean and systolic BP were lower in Group D at various time points following bolus administration. CONCLUSION: A single dose of dexmedetomidine as an additive to epidural local anesthetic postoperatively prolongs the duration of analgesia in comparison to fentanyl but is associated with changes in hemodynamics, including the need for the administration of vasoactive drugs.