Study objectives: To determine if transcutaneous electrical nerve stimulation (TENS) can produce fingertip analgesia.
Design: Randomized, crossover trial.
Participants: Fifteen healthy volunteers, naive to the technique of TENS.
Interventions: TENS stimulation was applied to the middle and ring fingers of each subject's hands by means of small carbon electrodes placed over the digital nerves. Patients received one fingertip puncture from a mechanically driven sterile lancet device to each digit corresponding to one of four conditions: sham, one minute of TENS, ten minutes of TENS, and 20 minutes of TENS. The TENS unit was operated in the "burst" mode, with two eight-pulse burst groups per second (pulse width, 225 psec; pulse frequency, 80 Hz). The order of the conditions and the finger used for each condition were assigned randomly. The pain of each puncture was rated on a 10-cm visual-analog scale. Data were analyzed using a repeated-measures analysis of variance with Duncan's multiple comparisons procedure.
Measurements and results: Mean visual-analog scale scores decreased sequentially from sham in each experimental condition: one minute of TENS, 24.4% (P< .025); ten minutes of TENS, 28.2% (P< .025); and 20 minutes of TENS, 55.7% (P< 10-e). Two patients had total anesthesia of the fingertip (visual-analog scale = 0 cm) in the 20minute TENS condition.
Conclusion: TENS significantly reduces the pain of lancet-induced trauma to the fingertip. Further studies are warranted to determine if this technique is useful clinically as an alternative or adjunct to digital nerve block anesthesia for fingertip surgical procedures.