Comparação do trajeto da agulha, dispersão anestésica e qualidade da anestesia nos bloqueios retrobulbar ou peribulbar

Abstract

The purpose of the study was to determine the needle course during intraconal or extraconal ophthalmic needle blocks and to observe their relation with the anesthetic solution dispersion and the efficacy of the anesthesia. This is a prospective, comparative study with patients undergoing phacoemulsification. All patients had an ophthalmic blockade with a 25 x 7mm needle through a single inferior-lateral transcutaneous puncture. Then, 5ml of anesthetic solution with radiologic contrast (omnipaque®) were injected. All patients were randomly allocated into two groups, GI - retrobulbar, and GII- peribulbar blockade. Orbital computerized tomographies were performed during the procedure and 10 minutes after the blockage to observe the needle course and anesthetic solution dispersion, respectively. The efficacy of the anesthesia was obtained measuring ocular mobility at 3, 5 and 10 minutes. Forty eyes from 40 patients were included (20 per group). The needle course was completely intraconal in 10 cases in GI and in no patient in GII. It transfixed the muscular cone in 5 cases in GI and in 4 eyes in GII. It was extraconal in 2 cases in GI and in 13 eyes in GII. The anesthetic solution dispersion always followed the needle course. Better efficacy was obtained in the intraconal blockade compared to the extraconal one (p<0.001). Independently of how the blockade was performed, in all extraconal needle courses the anesthesia was considered insufficient. It was only considered sufficient when the cone was transfixed or in the intraconal needle course (p = 1.0). Thus, the needle course was responsible for the anesthetic solution dispersion and directly related to the quality of the anesthesia. Retrobulbar blockade was more efficient than the peribulbar one.