Holmium:YAG lithotripsy: photothermal mechanism converts uric acid calculi to cyanide.
OBJECTIVE
Holmium:YAG lithotripsy fragments stones through a photothermal mechanism. Uric acid when heated is known to be converted into cyanide. We test the hypothesis that holmium: YAG lithotripsy of uric acid calculi produces cyanide.


METHODS
Human calculi of known uric acid composition were irradiated with holmium:YAG energy in water. Stones received a total holmium:YAG energy of 0 (control), 0.1, 0.25, 0.5, 0.75, 1.0 or 1.25 kJ. The water in which lithotripsy was performed was analyzed for cyanide concentration. A graph was constructed to relate holmium:YAG energy to cyanide production.


RESULTS
Holmium:YAG lithotripsy of uric acid calculi in vitro produced cyanide consistently. Cyanide production correlated with total holmium:YAG energy (p <0.001).


CONCLUSIONS
Holmium:YAG lithotripsy of uric acid calculi risks production of cyanide. This study raises significant safety issues.
Division of Urology, University of Texas Health Science Center and Brooke Army Medical Center, San Antonio, USA.
J M
JM
Teichman
G J
GJ
Vassar
R D
RD
Glickman
C M
CM
Beserra
S J
SJ
Cina
I M
IM
Thompson
D000538:Aluminum Silicates; D000704:Analysis of Variance; D002129:Calcium Oxalate / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry; D004396:Coloring Agents; D003486:Cyanides / Q000032:analysis / Q000737:chemistry*; D003553:Cystine / Q000737:chemistry; D006695:Holmium; D006358:Hot Temperature; D006801:Humans; D008027:Light; D017602:Lithotripsy, Laser; D017616:Magnesium Compounds / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D011829:Radiation Dosage; D012044:Regression Analysis; D012449:Safety; D000069877:Struvite; D013464:Sulfuric Acids / Q000737:chemistry; D014527:Uric Acid / Q000032:analysis / Q000737:chemistry*; D014545:Urinary Calculi / Q000737:chemistry*; D014867:Water; D015019:Yttrium
D000538:Aluminum Silicates; D002130:Calcium Phosphates; D004396:Coloring Agents; D003486:Cyanides; D017616:Magnesium Compounds; D010710:Phosphates; D013464:Sulfuric Acids; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D014867:Water; D002129:Calcium Oxalate; D014527:Uric Acid; D003553:Cystine; D015019:Yttrium; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D000069877:Struvite; C485829:calcium phosphate, dibasic, anhydrous; D006695:Holmium