Virtually painless local anesthesia: diluted lidocaine proves to be superior to buffered lidocaine for subcutaneous infiltration.

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.