Local digital anesthesia by lidocaine with and without bicarbonate

Purpose of the study Local anesthesia with lidocaine is widely used in surgery of the extremitie s, particularly for fingers. Injection causes pain. In order to minimize th is discomfort, addition of bicarbonate has been used by many authors. Resul ts were however contradictory in relation with the difference of approaches . Our study is based on a randomized comparative series with and without li docaine alcalinization. Material and methods Sixty patients presenting multidigital trauma concerning at least two finge rs. For each patient, one finger was anesthetized by lidocaine 2 per cent a lone and one by lidocaine 2 per cent plus bicarbonate 8.4 per cent respecti vely in proportion of 4/5 and 1/5, We compared the intensity of pain during injection by a scale ranging from 0 to 10. Results Significant difference was found between both groups (p < 0.001), alcaliniz ation appearing to decrease discomfort during injection. Discussion Mechanism of pain decrease by alcalinization is unclear. It appears that in tracellular passage of non ionic form of lidocaine is facilitated by alcali nization, This allows the decrease of latence of lidocaine and relieve pain more rapidely by pain receptors blockade. Conclusion Diminution of pain during anesthetic injection has major advantage in out-p atient surgery of extremities, in ligamentar testing of digital articulatio ns and in steroid injection.