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.