[Effects of CO2 and adrenaline on 1% lidocaine in axillary block].

OBJECTIVES

To compare lidocaine hydrocarbonate and lidocaine hydrochloride, with and without adrenaline, in the axillary block obtained with a neurostimulator.

STUDY DESIGN

Prospective, randomized, double blind study.

PATIENTS

Sixty-six patients undergoing surgery of the upper limb under axillary block, allocated into four groups.

METHODS

The criteria for evaluation were: onset time, duration and quality of sensory and motor blockades, and blood concentrations of lidocaine in 39 patients. In all patients musculocutaneous, radial, median and ulnar nerves were stimulated and the volume of local anaesthetic administered was 25 mL 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 1/200,000 (n = 16).

RESULTS

No significant inter-group differences were found concerning sensory and motor blockades and onset time. The duration of analgesia was longer in groups CO2 + A and HCL + A. The lidocaine blood concentrations were globally lower in group HCL + A.

CONCLUSIONS

Considering the cost/benefit ratio and the absence of clinical benefits of lidocaine hydrocarbonate, lidocaine hydrochloride should be preferred.