Novel laser type treats urinary stones safely and more efficiently

Novel laser type treats urinary stones safely and more efficiently Laser irradiation is a common method used to destroy urinary stones. More effective laser technology has been introduced recently, but some think it may be slightly more dangerous than the conventional approach. The researchers from Sechenov University prove the safety of the new technique.

Urinary stones, despite remaining sometimes unnoticed by the patients, are able to cause pain when moving and can lead to infection and inflammation. Current diagnostic methods are largely based on ureteroscopy, or examination of the upper urinary tract, whereas the treatment often involves lithotripsy, a procedure which uses laser irradiation to break down the stones. The remaining small particles then leave the body during urination. Different lasers may be used for this treatment, however, there are concerns that the local temperature upon irradiation may vary significantly depending on the laser type. Scientists from Sechenov University have compared the effects of two laser systems and ruled out that the temperature differences are not crucial. Their findings are reported in the World Journal of Urology.

The current gold standard for ureteroscopy and lithotripsy is a holmium:yttrium–aluminium–garnet (Ho:YAG) laser. More recently, the super pulse thulium fibre laser (SP TFL) was introduced as a competing, more effective technology. SP TFL has been shown to have a 3 times greater ablation rate and 3 times lower retropulsion, compared to Ho:YAG.

The study by Sechenov scientists included in vitro experiments aiming to measure the thermal effects of the two lasers. For example, irradiated water in insulated cuvettes warmed up to comparable temperatures in both cases. Similar results were obtained for the setup with irrigation flow.

It is believed that tissue injury begins at 43°C. The Ho:YAG laser, although sufficiently studied, may produce potentially dangerous temperatures up to 70°C. To prevent negative consequences, the technique should employ increased irrigation and intermittent laser activation. At the same time, the SP TFL was thought to be more dangerous because of its higher absorption. The experiments performed by Sechenov researchers have eradicated this belief, proving the safety of SP TFL.

‘Lasers have exceptional efficacy in lithotripsy, mostly due to the introduction of the Ho:YAG laser which is now the instrument of choice for stone ablation. The technique has some drawbacks, however — increased retropulsion, inability to use smaller laser fibres, and limited dusting efficacy’, said Mark Taratkin, a member of the Institute for Urology and Reproductive Health at Sechenov University and the first author of the paper. ‘The novel SP TFL technology was introduced a few years ago, surpassing the Ho:YAG in efficacy. To demonstrate the thermal safety of SP TFL, we performed a series of tests in the Laser Technology Lab of Sechenov University. We have shown that SP TFL has a temperature profile comparable to that of the conventional Ho:YAG laser’.

The study was carried out by Sechenov University (Institute for Urology and Reproductive Health, Department of Public Health and Healthcare Organisation, Institute of Linguistics and Intercultural Communication) and UT Southwestern Medical Centre (Dallas, TX, USA).

Read more: Taratkin M, Laukhtina E, Singla N et al. Temperature changes during laser lithotripsy with Ho:YAG laser and novel Tm-fiber laser: a comparative in-vitro study. World J Urol (2020).

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