Holmium: YAG lithotripsy: optimal power settings

Area of Science:

• Urology
• Laser Medicine
• Biomedical Engineering

Background:

• Holmium:YAG (Ho:YAG) laser lithotripsy is a common procedure for stone removal.
• Optimizing lithotripsy parameters is crucial for efficiency and safety.
• Understanding the relationship between pulse energy, frequency, and fiber durability is essential.

Purpose of the Study:

• To test the hypothesis that Ho:YAG laser lithotripsy speed is maximized using low pulse energy at high pulse frequency.
• To evaluate the impact of pulse energy and irradiation on optical fiber damage.
• To determine how lithotripsy efficiency and fragment size vary with different laser settings.

Main Methods:

• Irradiated various calculi (CHPD, COM, cystine, MAPH, uric acid) with a 365-microm optical fiber at pulse energies from 0.5 to 2.0 J.
• Measured optical energy output and fragmentation efficiency at different total energy levels (200 J to 1 kJ).
• Characterized fragment size using different optical fibers (272-microm to 940-microm) and pulse energies (0.5 J to 1.5 J).

Main Results:

• Optical fiber damage varied significantly with stone composition, being greatest for CHPD, MAPH, and COM.
• Fragmentation efficiency for CHPD was highest at pulse energies ≤1.0 J.
• Lithotripsy speed was consistently greatest at high power settings, and fragment size increased with pulse energy.

Conclusions:

• Optical fiber degradation is dependent on stone composition, irradiation, and pulse energy.
• Ho:YAG lithotripsy speed is enhanced by higher power, achieved through increased pulse energy or frequency.
• Using pulse energies ≤1.0 J at high repetition rates offers a balance of speed, safety, and smaller fragment generation.