Laser lithotripsy and cyanide

Area of Science:

• Urology
• Biomedical Engineering
• Laser Physics

Background:

• Holmium:YAG (Ho:YAG) laser lithotripsy of uric acid calculi can generate cyanide.
• The precise laser and stone parameters influencing cyanide production are not well-defined.

Purpose of the Study:

• To investigate if cyanide production during Ho:YAG lithotripsy varies with power settings.
• To compare cyanide production among Ho:YAG, pulsed-dye, and alexandrite lasers.
• To determine if Ho:YAG lithotripsy of all purine calculi produces cyanide.

Main Methods:

• Ho:YAG lithotripsy of uric acid calculi was performed using varying optical fiber diameters and pulse energies.
• Fragmentation, cyanide levels, and fragment sizes were quantified.
• Uric acid calculi were irradiated with Ho:YAG, pulsed-dye, and alexandrite lasers to compare cyanide production and fragmentation.
• Ho:YAG lithotripsy of various stone compositions (purine and non-purine) was conducted to assess cyanide generation.

Main Results:

• Cyanide production and fragment size increased with Ho:YAG pulse energy.
• Ho:YAG lasers produced significantly more cyanide than pulsed-dye and alexandrite lasers, both in absolute amounts and normalized for fragmentation.
• All tested purine calculi (monosodium urate, uric acid, xanthine, ammonium acid urate) generated cyanide during Ho:YAG lithotripsy.

Conclusions:

• Ho:YAG pulse energy directly influences cyanide production.
• Optimal Ho:YAG lasertripsy settings to minimize cyanide and fragment size are pulse energy ≤ 1.0 J.
• Cyanide production during laser lithotripsy of uric acid calculi differs significantly among laser types and is linked to pulse duration.