Effect of topical eutectic mixture of local anesthetics on pain response and analgesic requirement during lithotripsy procedures.

Abstract

We sought to determine whether topically applied eutectic mixture of local anesthetics (EMLA) would decrease analgesic requirement during extracorporeal shock wave lithotripsy (ESWL). Fifty-nine healthy out-patients undergoing elective ESWL using an unmodified Dornier HM-3 lithotriptor were randomly assigned to receive either a topical EMLA or placebo cream applied to the skin of the flank overlying the kidney 90 min prior to the ESWL procedure. Patients were given five test shocks at each of five different energy levels: 10, 12, 15, 18, and 20 kV. Patients evaluated the average pain at each stimulus level using a visual analog scale. Overall pain scores were significantly lower in EMLA-treated patients at 18 and 20 kV (P < 0.05). EMLA cream was significantly more effective at decreasing cutaneous pain in male than in female patients. However, during the lithotripsy procedure, EMLA cream had no significant effect on the intraoperative requirement for intravenous alfentanil, hemodynamic variables, recovery times, or postoperative side effects. Although the topical application of EMLA cream produced cutaneous analgesia, these data suggest that it failed to produce any opioid-sparing effect during the immersion lithotripsy procedure.