WARMING LIGNOCAINE TO REDUCE PAIN ASSOCIATED WITH INJECTION

Objective-To investigate the effect of warming lignocaine on the pain associated with subcutaneous injection. Design-Double blind, randomised, crossover study. Setting-Hospital clinic. Subjects-40 healthy volunteers. Interventions-Subcutaneous injection with 1 ml of 1% lignocaine at 20-degrees-C and 1 ml of 1% lignocaine at 37-degrees-C. Main outcome measures-Pain assessed by linear analogue pain scores and subjects' comparison of pain on injection. Results-25 subjects (89%; 95% confidence interval 72% to 98%) thought that lignocaine at 20-degrees-C was more painful and 3 (11%; 2% to 28%) thought that lignocaine at 37-degrees-C was more painful (p<0.0001); 12 subjects did not express a difference. Median pain score for injection at 20-degrees-C was 11.00 and at 37-degrees-C was 3.25 (p<0.001). Median difference was 8.25 (4.00 to 13.50). Conclusions-The simple procedure of warming to 37-degrees-C reduced the pain associated with subcutaneous injection of lignocaine.