Five years experience in experimental laser lithotripsy

In the first part of our experience approximately 300 stones of different composition have been treated in vitro with three different laser sources: Nd-YAG laser (1,064 nm), dye laser (504 nm) and alexandrite laser (755 nm). Calcium oxalate monohydrate and brushite stones appeared to be the most resistant to lithotripsy. Highest fragmentation rates were obtained for calcium oxalate dihydrate stones followed by struvite, uric acid and hydroxyapatite stones. The Nd-YAG laser did not appear to be ideal for lithotripsy since early damage to the fiber tip was observed when this source was used. Both the dye and the alexandrite lasers were almost always effective in fragmenting the various types of stones. We subsequently treated some cystine stones while immersed in water or in solutions of carmine indigo (2%), methylene blue (5%), rifamycin (0.6 and 6%) and rifampicin (0.8 and 0.3%) with the dye or the alexandrite laser. The spectra of these solutions, previously analyzed with the spectrophotometer, showed that rifamycin and rifampicin absorbed large amounts of light radiation at the wave length of the dye laser (504 nm). Successful fragmentation occurred only when the dye laser was used to treat stones immersed in the more concentrated solutions of these two substances. The quantity of fragmented material after treating a 10-cm3 cystine stone previously immersed in the more concentrated solutions of rifamycin and rifampicin (30 and 10 mm3, respectively) confirmed previous results.