Bloqueio peribulbar com associação de clonidina e hialuronidase à ropivacaína em cães submetidos à facectomias

Abstract

A wide range of ophtalmopathies affects animals visual quality as in lens opacification or cataract. To adress this, safer and efficient corrections are demanded and facectomy is the ellected thecnique, which, demands a general anesthesia, centralization and acenesia of ocular bulb, mydriasis, maintenance do intraocular pressure (IOP) and inhibition of ocularcardiac reflexes (OCR). Alternatively, to general anesthesia, local block is preferred bacause if promotes the other signs safely and provides more comfort to the patient. WE investigated the association of clonidine-hyaluronidase-ropivacaine in peribulbar anesthesia in dogs evaluating ocular and sistemic physiological parameters. Eight animals were investigated, counted 16 eyes, arrangeg 8 eyes for local block (OB) and the controlateral was defined as control (n=8, OC) . We performed a single-point low-volume (1.0 ml) thechnique. Injection volume contained clonidine (1 μg/kg), hyaluronidase (25 UTR) and ropivacaine 1% (10mg/mL) and was followed by premedication, induction and inhalatory general anesthesia. We evaluated parameters at time 0 (T0) – before peribulbar block, and post peribulbar block at 1 minute (T1) and at 10 mintues for IOP; we measured pupilar diameter, latency and time duration of motor block, akinesia and centralization of eye bulb as well as physiological parameters as cardiac and respiratory rate and frequency, mean arterial pressure, cardiac rhythm, capynometry and rectal temperature. Patients were rated as ASA 2 (75%) and ASA 3 (25%). Facectomy time extended for 72.87± 17.41 minutes, in which, mydriasis ocorrued at 67.75 ± 43.38 seconds; bulb centralizations at 67.75 ± 43.38 seconds; motor block extended for 162 ± 18.9 minutes. Pupilar dialation was significant after peribulbar block. No significant rate was observed for IOP - T0 (OC: 13.13 ± 3.37 OB: 12.13 ± 1.76), TBP1 (OC: 13.50 ± 2.96 OB: 12.13 ± 2.37) e TBP10 (OC: 13.53 ± 4.18 OB: 12.75 ± 2.17). No positive correlation between ropivacaine dose and peribulbar block effect could be determined, however, we detach that ropivacaine dosage for each animal was below the indicated therapeutcis limits for the specie. Physiological parameter were considered normally observed along the anesthesia procedure and reverted to basal rates at recovery and no complications were diagnosed. In all patientes, OCR or any complication relationed to peribulbar block were not observed. We conclude that periblubar block for facectomy using clonidine-hyaluronidase-ropivacaine (C-H-R) association in a 1 mL volume promotes low latency, long duration and mydriasis with no side effects.