70 W holmium: yttrium-aluminum-garnet laser in percutaneous nephrolithotomy for staghorn calculi

To investigate the safety and efficacy of the high-power (70 W) holmium laser in percutaneous nephrolithotripsy (PCNL) for staghorn calculi.

From December 2004 to March 2008, 438 consecutive patients (456 renal units) with > or =4-cm staghorn stones underwent PCNL with a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser using a 1000-microm end-firing optical fiber. For the first 106 patients (group A; average stone size 5.6 +/- 0.8 cm), a 30 W (3.0 J/pulse; 10 pulse/sec) laser was used, whereas for the other 332 patients (group B; average stone size 5.8 +/- 0.8 cm), the laser power was set at 3.0 J/pulse with a frequency of 20 pulses/sec. For stones in a calix visible with the nephroscope but unreachable with a laser, the mucosa of the calix was split with a 100 W holmium laser to fragment the stones further. Moreover, a porcine model for assessing the safety of the high-power holmium laser was developed.

All patients had successful PCNL. The average lithotripsy time in group B was significantly shorter than that in group A (44 +/- 11.5 minutes vs 69 +/- 14.8 minutes; P < 0.05). No patient had a severe complication. In addition, 39 patients underwent calix splitting with no hemorrhage during or after the operation. The glomerular filtration rate of the treated kidney, reexamined 6 months after the operation, had improved greatly (45.12 vs 31.91 mL/min; P < 0.05). Pathologic evaluation of porcine kidneys exposed to high-power laser firing showed no damage.

The high-power Ho:YAG laser enhances lithotripsy efficacy by "vaporizing" and "bursting" the stone quickly, reducing lithotripsy time significantly. This is an effective and safe treatment for patients with large renal stones.