The use of local anesthesia in second generation extracorporeal shock wave lithotripsy: eutectic mixture of local anesthetics.

Extracorporeal shock wave lithotripsy (ESWL&) can be painful. Of our population of patients treated with a Siemens Lithostar device 51.4% needed intravenous analgesia. A eutectic mixture of local anesthetics, a hydrophylic cream containing 25 mg. lidocaine and 25 mg. prilocaine per gm., proved to be effective for local analgesia. Therefore, we investigated its effectiveness during ESWL. With randomized, double-blind application the eutectic mixture of local anesthetics and placebo were evaluated in 83 patients according to the percentage of patients who required intravenous analgesia during ESWL. Of 40 patients treated with the eutectic mixture of local anesthetics 12 (30%) needed supplementary fentanyl citrate, compared to 23 of 43 (53%) placebo treated patients. Although there is no statistical significance (p = 0.32), the eutectic mixture of local anesthetics does decrease pain during ESWL and it should be particularly useful for patients in whom intravenous analgesia is contraindicated.