Distal paravertebral nerve block in sheep undergoing laparohysterotomy: Comparing the use of 1% and 2% lignocaine hydrochloride

Abstract

Abstract The study was designed as a blinded, randomized, prospective, clinical trial to compare the use of 1% and 2% lignocaine hydrochloride for distal paravertebral nerve block in sheep undergoing Caesarian section. Full-term ewes (n = 18) with dystocia requiring laparohysterotomy were randomly and equally allotted to two groups (I and II). They were administered ceftriaxone (10 mg kg−1) and meloxicam (0.3 mg kg−1, IM) 30 min and diazepam (0.2 mg kg−1, IV) 15 min before injecting 15.0 mL (5.0 mL per spinal nerve) of either 1% (Group I) or 2% (Group II) lignocaine hydrochloride for achieving distal paravertebral anesthesia. Nociceptive stimuli during pre- and postoperative periods comprised of superficial and deep pinpricks. The reaction of the animals to the surgical intervention, manipulations and application of the sutures were recorded intraoperatively. Routine postoperative management included regular wound dressing, administration of the antibiotic and analgesic. The onset time (mean ± standard deviation) of the regional anesthesia in group I and II ewes was 4.6 ± 1.5 min and 5.4 ± 2.8 min respectively. One sheep per group showed temporary, mild muscle twitching near ventral flank but required no rescue analgesia. The duration of surgery was 52 ± 11 min and 60 ± 11 min and the anesthesia lasted for 87 ± 15 min and 98 ± 17 min respectively. Significant difference between the groups was not detected in any of these variables. From this clinical study it is concluded that satisfactory flank anesthesia is achieved using 2% or 1% lignocaine hydrochloride for distal paravertebral nerve block. The recommendation to use 1% instead of 2% local anesthetic preparation for safety in small ruminants is thus validated.