Recommended Laser Settings for Renal Stone Treatment During RIRS
Use the lowest effective power settings that achieve adequate fragmentation—typically 20-30 W for Ho:YAG laser—as higher power settings up to 120 W do not improve stone-free rates, morbidity, or mortality, but do increase thermal injury risk. 1
Evidence-Based Power Recommendations
Ho:YAG Laser Settings (Gold Standard)
For 1-2 cm renal stones, use 30 W Ho:YAG devices, which provide higher stone-free rates and fewer auxiliary procedures compared to 20 W devices while maintaining safety 1, 2
Keep power at "reasonable" levels to limit intrarenal temperature rise and minimize thermal injury risk 1
Low-power settings (<20 W) with minimal irrigation flow (5-10 ml/min) are sufficient to maintain safe intrarenal temperatures and allow continuous laser activation 3
Specific Setting Strategies
Two validated approaches exist:
High-frequency, low-pulse energy (HiFr-LoPE): 0.2-0.8 joules at 10-20 Hz for dusting technique 4
Low-frequency, high-pulse energy (LoFr-HiPE): 1.5-2.0 joules at 30-40 Hz for stone self-popping technique, which reduces operative time by approximately 14 minutes without compromising stone-free rates 5
Thulium Fiber Laser (TFL)
TFL demonstrates efficacy comparable to Ho:YAG laser and can be used interchangeably for renal stone fragmentation 1, 6
TFL at 60 W provides similar stone-free rates (97.9% vs 95.8%) with significantly shorter basketing time compared to 120 W Ho:YAG with MOSES technology 7
TFL and Ho:YAG at similar settings (0.2 J/40 Hz) produce comparable temperature increases, with heating rate proportional to laser power 8
Critical Safety Considerations
Temperature and Pressure Management
Higher frequencies increase thermal damage risk despite power equivalence, making proper irrigation critical 8
Intrarenal pressure and temperature are closely related; continuous monitoring helps avoid barotraumatic and septic complications 3
Ureteral access sheath, low irrigation pressure, and occupied working channel help maintain safe intrarenal pressure 3
Common Pitfalls to Avoid
Do not assume higher power equals better outcomes: High-power settings up to 120 W shorten active lasering time but provide no improvement in stone-free rates, morbidity, or mortality 1
Avoid excessive frequency settings: When delivered energy increases through higher frequencies rather than pulse energy, thermal damage increases disproportionately 8
Maintain adequate irrigation: Low frequency settings combined with proper irrigation (5-10 ml/min) are critical to prevent thermal injury during endoscopic laser lithotripsy 3, 8