Peribulbar Sub-Tenon’s Anaesthesia With Levo-Bupivacaine and Cis-Atracurium Besilate in Ophthalmic Intraocular Surgery in Cat: Clinical Study.

Abstract Backgroundthis study aims to evaluate the efficacy of Levo-bupivacaine with the addition of a small dose of cisatracurium by sub-Tenon’s injection on akinesia and mydriasis. Then, to evaluate if such a small dose of cisatracurium could determine a systemic neuromuscular blockade, despite the way of administration. Forty cats were anesthetized for intra-ophthalmic surgery with butorphanol 0,2 mgkg-1, dexmedetomidine 15 mcg/kg and midazolam 0,2 mgkg-1 IM and intubated to receive oxygen and isofluorane by mechanical ventilation. The animals were divided in four groups. Group L received 1.25 mgkg-1 L-bupivacaine, administered by peribulbar injection; group CL received the same dose of L-bupivacaine, combined with 0.01mg/kg of cisatracurium; group C received 0.01 mg kg-1 of peribulbar cisatracurium; group GC received 0.01 mg kg-1 of cisatracurium intravenously. Physiological variables and oculomotor activity were measured before and up to 30 minutes after peribulbar injection.ResultsThe data below, expressed with median and range, show that physiological variables remained in the physiological range. Among the treatments, the LC group showed akinesia, higher midriasis and a decrasing intraocular pressure (IOP); the onset time of akinesia was significantly shorter in group LC than in group L 4(3/5) min and 8(6/10) min respectively, p=0.000; the duration of akinesia was longer in group LC than in group L, 70(68/72) and 60(57/63min), respectively p=0.000. In group C we observed the appearance of akinesia after 5(5/5) minutes from the peribulbar administration and it lasted for 20(20/20) minutes (p=0.000), compared to groups L and LC. In group GC we registered akinesia after 5(5/5) minutes, but the duration observed was shorter 5(5/6). In groups C and GC, additional L bupivacaine peribulbar injection was required. The train of four (TOF) was ≥ 0.9 throughout the study in all of the groups. ConclusionsA combination of cisatracurium and L-bupivicaine, used for peribulbar sub-Tenon’s anesthesia, provides effective akinesia, midriasis of the eye, shortens the onset of akinesia and prolongs its duration, thus providing excellent conditions for intra-ophthalmic surgery, without incurring in a systemic blockade.