Comparative evaluation of dexmedetomidine and fentanyl for epidural analgesia in lower limb orthopedic surgeries.

BACKGROUND AND AIMS: Opioids as epidural adjunct to local anesthetics (LA) have been in use since long and α-2 agonists are being increasingly used for similar purpose. The present study aims at comparing the hemodynamic, sedative, and analgesia potentiating effects of epidurally administered fentanyl and dexmedetomidine when combined with ropivacaine.

METHODS: A total of one hundred patients of both gender aged 21-56 years, American Society of Anaesthesiologist (ASA) physical status I and II who underwent lower limb orthopedic surgery were enrolled into the present study. Patients were randomly divided into two groups: Ropivacaine + Dexmedetomidine (RD) and Ropivacaine + Fentanyl (RF), comprising 50 patie nts each. Inj. Ropivacaine, 15 ml of 0.75%, was administered epidurally in both the groups with addition of 1 μg/kg of dexmedetomidine in RD group and 1 μg/kg of fentanyl in RF group. Besides cardio-respiratory parameters and sedation scores, various block characteristics were also observed which included time to onset of analgesia at T10, maximum sensory analgesic level, time to complete motor blockade, time to two segmental dermatomal regressions, and time to first rescue analgesic. At the end of study, data was compiled systematically and analyzed using ANOVA with post-hoc significance, Chi-square test and Fisher's exact test. Value of P<0.05 is considered significant and P<0.001 as highly significant.

RESULTS: The demographic profile of patients was comparable in both the groups. Onset of sensory analgesia at T10 (7.12±2.44 vs 9.14±2.94) and establishment of complete motor blockade (18.16±4.52 vs 22.98±4.78) was significantly earlier in the RD group. Postoperative analgesia was prolonged significantly in the RD group (366.62±24.42) and consequently low dose consumption of local anaesthetic LA (76.82±14.28 vs 104.35±18.96) during epidural top-ups postoperatively. Sedation scores were much better in the RD group and highly significant on statistical comparison (P<0.001). Incidence of nausea and vomiting was significantly high in the RF group (26% and 12%), while incidence of dry mouth was significantly higher in the RD group (14%) (P<0.05).

CONCLUSIONS: Dexmedetomidine seems to be a better alternative to fentanyl as an epidural adjuvant as it provides comparable stable hemodynamics, early onset, and establishment of sensory anesthesia, prolonged post-op analgesia, lower consumption of post-op LA for epidural analgesia, and much better sedation levels.