The importance of needle gauge for pain during injection of lidocaine.

BACKGROUND

Local anaesthetics such as lidocaine are used both in minor and major surgical procedures, and can be painful. Different methods have been investigated to reduce the discomfort of the injections. This study investigated if different needle gauges can influence the pain experienced during injection of lidocaine.

METHODS

A randomised study was performed on 36 healthy volunteers. Each participant received three injections of 3 ml 1% lidocaine subcutaneously on the abdomen using needles of different gauges. Following each injection, the participants evaluated the pain experienced on a visual analogue scale (VAS). After the session, they were asked to evaluate verbally which injection they found least and most painful. The VAS and verbal reports were used and compared to evaluate the difference between the two types of clinically reported pain scales.

RESULTS

Twenty-one participants verbally reported the thinnest needle (27 gauge (G)) as least painful, compared to the intermediate (23 gauge; p = 0.013) and the thickest needle (21 gauge, p = 0.004). The mean VAS scores were 19 (SD = 13) for the 21 gauge, 18 (SD = 13) for the 23 gauge, and 16 (SD = 14) for the 27 gauge needles.

CONCLUSION

A significant preponderance of respondents stated that there had been less pain using the thinnest needle. Mean VAS responses showed the same trend, but the differences between them were not statistically significant.