The effect of addition of low dose atracurium to local anesthetic in retrobulbar block for cataract surgery.

BACKGROUND Addition of some neuromuscular blockers to local anesthetics proved to be effective in improving the quality of anesthesia in different regional techniques. This study was carried out to determine whether the addition of low-dose atracurium to a local anesthetic has any effect on the onset and duration of akinesia in retrobulbar block. PATIENTS AND METHODS This study was conducted on sixty-four unpremedicated, ASA I or 11 patients scheduled for cataract surgery under local anesthesia. The patients were assigned to one of the two treatment groups in a randomized, double-blind manner. The case group received 2 ml of 2% lidocaine (40 mg) and 0.5 mL atracurium (5 mg). The control group received 2 ml of 2% lidocaine (40 mg) and 0.5 ml 0.9% NaCl. The onset of akinesia (the inability to move the eye in all four directions) was scored as 0 to 2:0, no akinesia; 1, partial akinesia; and 2, complete akinesia. The onset and duration of akinesia and also adverse effects and complications of each method were recorded throughout the study. RESULTS In 4 out of 64 patients, complete akinesia was not achieved and statistical analysis was done on 60 others with complete akinesia. With regard to age, sex, weight, and duration of the surgery, there were no significant differences between the case and control groups. The onset of complete akinesia was quicker and duration longer in the case group than in the control group. The onset of complete block was 4.7 +/- 1.1 minutes in the case group and 6.9 +/- 0.96 minutes in the control group (P < 0.001). The duration of akinesia was 104.07 +/- 17.6 minutes in the case group and 87.1 +/- 16.2 minutes in the control group (P < 0.001). CONCLUSION This study demonstrated that atracurium had a local action on the extraocular muscles. It shortened the onset period of retrobulbar block, prolonged its duration, and provided excellent surgical conditions without any specific complications.