Background: Many physicians believe that buffering local anesthetics with sodium bicarbonate is the best technique for reducing the pain and discomfort associated with subcutaneous infiltration.
Objective: To compare the level of pain and discomfort associated with subcutaneous infiltration of lidocaine diluted with normal saline to that associated with traditionally buffered lidocaine.
Patients/methods: In a prospective, double-blind trial, 31 patients were asked to use a visual analog scale to rank the level of pain and discomfort caused by two different solutions of lidocaine with epinephrine. Solution A: 3 mL of 1% lidocaine + epinephrine in 30 mL of bacteriostatic 0.9% sodium chloride in a 1:10 ratio, in which each mL contained 9 mg of sodium chloride and 9 mg of benzyl alcohol. Solution B: 5 mL of 8.4% sodium bicarbonate solution and 50 mL of 1% lidocaine + epinephrine in a 1:10 ratio.
Results: Twenty-eight out of 31 patients reported that the solution of lidocaine diluted with normal saline was the least painful upon injection.
Conclusion: Pain and discomfort during subcutaneous injection of lidocaine can be reduced by diluting the anesthetic with normal saline in a 1:10 ratio.