EFFECTS OF CO2 AND EPINEPHRINE ON LIDOCAI NE 1-PERCENT IN AXILLARY BLOCK

Objectives: To compare lidocaine hydrocarbonate and lidocaine hydrochl oride, with and without adrenaline, in the axillary block obtained wit h a neurostimulator. Study design: Prospective, randomized, double bli nd study, Patients: Sixty-six patients undergoing surgery of the upper limb under axillary block, allocated into four groups. Methods: The c riteria for evaluation were: onset time, duration and quality of senso ry and motor blockades, and blood concentrations of lidocaine in 39 pa tients. In all patients musculocutaneous, radial, median and ulnar ner ves were stimulated and the volume of local anaesthetic administered w as 25 mt per square meter of body surface. Group 1 received lidocaine hydrocarbonate 1% (n = 17), group 2, lidocaine hydrocarbonate 1% with adrenaline 1/200,000 (n = 17), group 3, lidocaine hydrochloride 1% (n = 16) and group 4, lidocaine hydrochloride 1% with adrenaline 1/200,00 0 (n = 16). Results: No significant inter-group differences were found concerning sensory and motor blockades and onset time. The duration o f analgesia was longer in groups CO2 + A and HCL + A. The lidocaine bl ood concentrations were globally lower in group HCL + A. Conclusions: Considering the cost/benefit ratio and the absence of clinical benefit s of lidocaine hydrocarbonate, lidocaine hydrochloride should be prefe rred.