Laser Lithotripsy: The Importance of Peak Power and Pulse Modulation

Despite the worldwide spread of Ho:YAG lasers in urology departments, the physical principles behind their functioning may still seem obscure to many urologists. Moreover, a new laser source, the thulium fiber laser (TFL), was recently approved for stone lithotripsy. Here we describe the concepts of peak power and pulse modulation for laser lithotripsy, analyzing both Ho:YAG lasers and TFLs. Different pulse modalities are available for Ho:YAG lasers-long and short pulses and Moses technology-each with a different pulse shape and peak power. Lower peak power and a more rectangular pulse shape provide higher ablation efficiency and lower stone retropulsion. These characteristics are perfectly embodied by TFL, which shows the most effective ablation efficiency in laboratory studies. A long pulse is the most effective modality for Ho:YAG lasers. Moses technology, despite its promising rationale, is not superior to long-pulse mode. Clinical studies are needed in order to confirm these laboratory data. PATIENT SUMMARY: Laser lithotripsy is one of the main options for the treatment of urinary stones. The peak power and pulse modulation influence the choice of the optimal laser mode for the treatment of urinary stones. Thulium fiber lasers have shown the most favorable dusting profile in terms of both peak power and pulse modality in laboratory studies, but clinical evidence is still lacking.