Vertical infraclavicular block with local anesthetic injections at different currents

Injecting local anesthetic at the seeking current would be appealing.It would save time and avoid potentially dangerous manipulations of the needle. This study aimed to test the hypotheses that in vertical infraclavicular block, injecting local anesthetic at a seeking current of 0.8 mA would produce the same quality of block as injecting at ≤0.5mA. A total of sixty ASA I -III adult patients scheduled for elective surgery on the hand, wrist and forearm in two equal groups of 30 patients, were enrolled in this study. The technique described by Kilka & Geiger used in both groups. After eliciting a clear and visible motor response of all fingers in either extension or flexion, injection was performed at a current of 0.8 mA and ≤0.5 mA in study and control groups respectively. Duration of time to analgesia and to anesthesia was evaluated. The mean duration of onset of analgesia in radial, median and ulnar nerves in both groups, were similar. The onset of anesthesia took a mean of 13.5 minutes in the control group and 15.6 minutes in study group (P=0.064).  The onset of analgesia was 4.2 minutes in the control group and 4.3 minutes in study group. (P=0.508). The success rate in both groups was 100%. We had patients in both groups who developed complete anesthesia of the hand within 25 minutes. We conclude that the injection at 0.8 mA would result in a similar quality of block to one injected at ≤0.5 mA. The difference between two groups was not statistically significant.