Comparison of the performance of two pulsed dye lasers using a synthetic stone model

The performance of two pulsed dye laser lithotripters was compared in vitro using a synthetic calculus with gross physical properties similar to natural urinary tract calculi. Synthetic calculi were subjected to 500 shocks at nominal pulse energies of 40, 60, 80, 100 and 120 mJ using a 320 micron. fiber. Three calculi were treated at each energy level on the Technomed Pulsolith and two at each level on the Candela MDL 2000. The pattern of fragmentation was similar with both lithotripters. Increasing the energy level resulted in a linear increase in fragmentation (Pulsolith r = 0.95, MDL 2000 r = 0.99), but fragmentation was greater with the MDL 2000 than with the Pulsolith (6.01 mg/mJ versus 5.00 mg./mJ, p < 0.001). Both lasers fragmented the calculi satisfactorily. We recommend that all users of such lasers acquire a laser meter to allow monitoring of the energy delivered by the fiber tip.