Increasing the pH of lidocaine decreased pain on injection and augmented patient comfort and satisfaction.
Comparison of three modified lidocaine solutions for use in eyelid anesthesia.
To compare pain on injection and the efficacy of anesthesia of three modified lidocaine solutions for use in eyelid surgery: 1) 2% lidocaine with 1:100,000 epinephrine, 2) 2% lidocaine with 1:100,000 epinephrine buffered 9:1 with 8.4% sodium bicarbonate, and 3) 2% lidocaine with 1:100,000 epinephrine diluted 1:9 with 0.9% bacteriostatic saline solution (with benzyl alcohol).
                In this prospective, randomized, double-masked, controlled clinical trial, 30 consecutive patients undergoing bilateral identical eyelid surgery were randomized to one of three treatment groups. Group 1 received buffered solution on one side and stock solution on the other, group 2 received bacteriostatic saline diluted solution on one side and stock solution on the other, and group 3 received buffered solution on one side and bacteriostatic saline diluted solution on the other. Patients used a 5-point scale to rate the perceived pain on injection and the pain felt during the operative procedure.
                Comparison of mean injection pain scores showed that buffered solution was significantly less painful than unmodified solution (2.2 versus 3.1, p < 0.05), bacteriostatic saline modified solution was significantly less painful than unmodified solution (0.9 versus 3.3, p < 0.05), bacteriostatic saline modified solution was significantly less painful than buffered solution (1.2 versus 2.3, p < 0.05). Comparison of mean intraoperative pain scores demonstrated no significant difference between the solutions in any of the treatment groups.
                For local anesthesia in eyelid surgery, bacteriostatic saline modified solution provides more comfort on injection than either buffered or unmodified lidocaine-epinephrine solution and provides an adequate level of anesthesia that does not differ significantly from either the buffered or unmodified solutions.