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.
Teichman
J M
JM
Division of Urology, University of Texas Health Science Center and Brooke Army Medical Center, San Antonio, USA.
Vassar
G J
GJ
Glickman
R D
RD
Beserra
C M
CM
Cina
S J
SJ
Thompson
I M
IM
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