COMPARISON OF DIFFERENT LITHOTRIPTERS IN REGARD TO DISINTEGRATIVE EFFICACY (DE) AND DISINTEGRATIVE RANGE (DR) USING AN IN-VITRO STONE MODEL

The disintegration capacity of shock wave sources plays an important part in the clinical efficacy of lithotripters. We endeavoured to assess the disintegrative efficacy and range of diverse shock wave generators by means of an established, standardized in vitro stone model. An artificial stone was focussed in a wire mesh and then disintegrated by shock waves (SW) until all fragments passed through the mesh. The reciprocal value of the required number of SW corresponded to the disintegrative efficacy (DE = 100/SW). The disintegrative range was calculated between minimum and maximum generator voltage (DR = DE(min) - DE(max)). These parameters varied distinctly between the electrohydraulic (Dornier HM 3, MPL 9000), electromagnetic (Storz Medical Modulith SL, Siemens Lithostar Plus undercouch- and overhead-module) and piezoelectric (Wolf Piezolith 2500 and 2300, EDAP LT02) generators tested. The correlation between SW and generator voltage enabled the determination of typical central lines for these machines. The Modulith SL, followed by both the electrohydraulic lithotripters, MPL 9000 and HM 3 demonstrated the highest disintegrative efficacy. The widest range was achieved by the piezoelectric lithotripters as well as the Lithostar undercouch module and the Modulith. The DE value for the generator voltage applied in clinical kidney stone lithotripsy was concurrent for the various SW sources between 0.2 and 0.9. The EDAP LT02 demonstrated inferior efficacy and therefore requires an alternative treatment strategy. However, there were distinct differences in output reserve in the high- and low-energy ranges, which are desirable for a wide spectrum of clinical indications.