Clinical effects of epidurally administered lidocaine with or without dexmedetomidine in sheep

The study was designed as a randomized, prospective, blinded, clinical trial to compare the clinical effects of epidural lidocaine hydrochloride 2% (L2%) alone and in combination with dexmedetomidine (DL2%) in sheep. A total of 19 adult sheep, 14 females & 5 males were assigned to one of the two lumbosacral epidural treatments: L2% (4mgkg –1) and DL2% (2.5µgkg –1 + 4mgkg –1) in a randomized order. The total volume of the drug combination was kept constant. Onset, analgesia, motor blockade, sedation and behaviour were determined before treatment, after effect of treatment and at recovery. Duration of epidural anesthesia and motor blockade were recorded. Heart rate, blood pressure, respiratory rate, rectal temperature and capillary refill time were recorded prior to treatments and every 15minutes following epidural anesthesia for 60minutes. Epidural anesthesia was produced with both the treatments effectively and was easily performed in all the studied animals. Both the treatments provided complete analgesia however no significant difference (p = 0.35) was recorded in onset time to analgesia. Duration of epidural anesthesia was significantly greater (p < 0.0001) with DL2% (239.56 ± 19.48min) than L2% (69.30 ± 3.03min). Significant extension (p < 0.0001) of motor blockade was recorded with DL2% (251.89 ± 22.18min) than with L2% (88.30 ± 2.36min) alone. The median analgesic scores were significantly higher in DL2% in comparison to the L2% alone. Rescue analgesia had to be given in 20% of L2% and 33.3% of DL2%.