Comparison of pH-adjusted bupivacaine with a mixture of non-pH-adjusted bupivacaine and lignocaine in primary vitreoretinal surgery.

Abstract

To compare the efficacy of alkalinized bupivacaine with that of a mixture of nonalkalinized bupivacaine and lignocaine for local anesthesia in primary vitreoretinal surgery. Through a prospective, double-blind, randomized, controlled clinical trial, 540 consecutive patients undergoing primary vitreoretinal surgery received either alkalinized 0.5% bupivacaine (group B) or a mixture of nonalkalinized 0.5% bupivacaine and 2% lignocaine (group BL), both of which were administered with hyaluronidase, for periocular anesthetic block. The periocular block involved two injections in the extraconal space-one in the lower temporal quadrant and the other in the medial periconal space. The efficacy of the block was graded from 0 to 5 depending on the adequacy of anesthesia and akinesia and the need for local supplementation. Adequate anesthesia and akinesia (grade 5) were achieved in 72.2% of the patients in group B compared with 57.4% in group BL (P = 0.0003). Intraoperative supplementation was needed in 9.6% and 20.7% of the patients in groups B and BL, respectively (P = 0.0003). Postoperative analgesics were required in 7.4% of the patients in group B and in 15.2% of those in group BL (P = 0.004). Alkalinized 0.5% bupivacaine provides better quality of anesthesia than does the mixture of nonalkalinized 0.5% bupivacaine and 2% lignocaine for patients undergoing primary vitreoretinal surgery.