Carpal ligament decompression under local anaesthesia: the effect of lidocaine warming and alkalinisation on infiltration pain.

This study investigated the effects of alkalinization and warming of lidocaine 1% on injection pain in patients undergoing carpal tunnel decompression. Sixty-four adult patients were randomly allocated into one of three groups: Group A (n=20) received plain lidocaine 1%, Group B (n=22) alkalinized lidocaine and Group C (n=22) warmed and alkalinized lidocaine. Pain on needle insertion and on infiltration was assessed using a 100mm Visual Analogue Scale (VAS). There was no significant difference regarding pain on needle insertion whereas significant differences were noted in reference to infiltration pain. In Groups B and C (alkalinized lidocaine) the VAS scores on skin infiltration were significantly lower than in Group A, while the pain score in Group C (alkalinized and warmed lidocaine) was significantly lower than in Group B.