Effect of the frequency of transcutaneous electrical nerve stimulation on analgesia during extracorporeal shock wave lithotripsy

In this prospective, randomised, sham controlled study, we set out to determine which transcutaneous electrical nerve stimulation (TENS) therapy modality (conventional vs acupuncture-like) is more effective as a supplementary analgesic regimen during extracorporeal shock wave lithotripsy (ESWL). Patients were prospectively randomised to one of three groups. In Group I (n=22), conventional TENS (impulse pattern: continuous at 80 Hz; intensity: 10-30 mA) was applied. In Group II (n=22) acupuncture-like TENS (impulse pattern: burst at 2 Hz; intensity: 15-50 mA) was applied. In Group III (n=22) (control group), stimulation was started at 1 mA and the intensity increased to no more than 10 mA until it produced a tickling sensation. Alfentanil was administered through a patient controlled analgesic device. Alfentanil consumption, hemodynamics and respiratory parameters, a 10-cm visual analogue pain scale, patient satisfaction, recovery and discharge times were evaluated. The consumption of alfentanil was significantly lower in Group I than in Groups II and III (P<0.0001). Pain scores were lower in Group I than in the other two groups (P<0.05). Patients in Group I were more satisfied with their analgesic medication than those in the other two groups (P<0.05). Both the time to an Aldrete score >8 and a modified post-anaesthetic discharge score >8 were significantly shorter in Group I (2.3+/-1.8, 49.1+/-14.6) than those of Groups II (4.6+/-2.2, 60.2+/-18.1) and III (4.9+/-2.8, 58.4+/-16.5) (P<0.0001 and P<0.05, respectively). We conclude that the use of conventional TENS is effective in decreasing the analgesic requirements and the incidence of alfentanil-related side effects during ESWL.