Combining Lithoclast and ultrasound power in one device for percutaneous nephrolithotomy: in vitro results of a novel and highly effective technology

Abstract 

Objectives

A new device for percutaneous nephrolithotomy, combining Lithoclast (LC) and ultrasound (US) lithotripsy, was developed. Under standardized in vitro conditions, we evaluated the efficacy of the new technique using artificial stones. Combined application of pneumatic and US lithotripsy was compared with each of the two components alone.

Methods

Five different artificial stones of defined hardness were used. Disintegration was performed under defined pressure in a water bath. The time until the first fragmentation and until complete disintegration to fragments of 2 mm or smaller was measured for LC and US alone and for combined lithotripsy. Furthermore, the disintegrated partition after 1 minute and time until 50% disintegration of each stone was determined.

Results

With regard to first fragmentation and complete disintegration, LC and US combination showed superior efficacy. First fragmentation was achieved 25 to 200 times faster and complete disintegration in a range of 11 to 15 minutes. No complete disintegration was possible by LC and US alone within a time limit of 20 minutes. The disintegrated stone mass after 1 minute was 1.5 to 4 times larger in combined lithotripsy and the 50% disintegration time was 30% to 50% compared with LC or US alone. No technical defects occurred.

Conclusions

Combining LC and US in one device for percutaneous nephrolithotomy shows promising in vitro results in an artificial stone model. It seems to provide superior efficacy in the disintegration parameters important for clinical practice.