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Laser lithotripsy mechanisms can cause the chemical decomposition of stone components and the emergence of different end products. However, the potentially toxic end products formed during thulium fiber laser (TFL) lithotripsy of cystine stones have not been sufficiently investigated. The aim of our in vitro study is to analyze the chemical content of the gas products formed during the fragmentation of cystine stone with TFL. Human renal calculi consisting of 100% pure cystine, calcium oxalate monohydrate, or uric acid were fragmented separately with TFL in experimental setups and observed for gas release. After the lithotripsy, only the cystine stones showed gas formation. Gas chromatography-mass spectrometry was used to analyze the gas qualitatively, and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction was used to examine the dried cystine stone fragments. Fragmentation of the cystine stones released free cystine, sulfur, hydrogen sulfide, and carbon disulfide gas. The SEM-EDX and X-ray diffraction analyses revealed that the free cystine in the dried fragments contained 43.1% oxygen, 28.7% sulfur, 16.1% nitrogen, and 12.1% carbon atoms according to atomic weight. The detection of potentially toxic gases after lithotripsy of cystine stones with TFL indicates a risk of in vivo production. Awareness needs to be increased among healthcare professionals to prevent potential inhalation and systemic toxicity for patients and operating room personnel during TFL lithotripsy of cystine stones., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The primary aim of the present in vitro study is to analyze the chemical content of the bubbles occurring during the fragmentation of cystine stones with both the high-power and low-power holmium:YAG (Ho:YAG) lasers. The secondary aim is to discuss their clinical importance. Three types of human renal calculi calcium oxalate monohydrate (COM), cystine, and uric acid were fragmented with both low-power and high-power Ho:YAG lasers in separate experimental setups at room temperature, during which time it was observed whether gas was produced. After laser lithotripsy, a cloudy white gas was obtained, after the fragmentation of cystine stones only. A qualitative gas content analysis was performed with a gas chromatography–mass spectrometry (GC–MS) device. The fragments in the aqueous cystine calculi setup were dried and taken to the laboratory to be examined by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX) and X-ray diffraction analysis. No gas production was observed after fragmentation in the COM and uric acid stones. Free cystine, sulfur, thiophene, and hydrogen sulfide gas were produced by both low-power and high-power Ho:YAG laser lithotripsy of the cystine stones. In the SEM–EDX mapping analysis, a free cystine molecule containing 42.8% sulfur (S), 21% oxygen (O), 14.9% carbon (C), and 21% nitrogen (N) atoms was detected in the cystine stone experimental setup. The evidence obtained, which shows that hydrogen sulfide emerges in the gaseous environment during Ho:YAG laser fragmentation of cystine stones, indicates that caution is required to prevent the risk of in vivo production and toxicity. [ABSTRACT FROM AUTHOR]