Holmium:YAG laser has been the lithotrite of choice for around 30 years in kidney stone surgery. Lasers have evolved over the years to offer higher power, increased pulse frequencies and longer pulse durations. The drivers for change have been to improve stone ablation and to minimise retropulsion. We report on a new prototype Holmium laser that fires multiple “micro-pulses” in “pulse packets” and discuss the stone phantom ablation rate results utilizing a bench model. The prototype laser demonstrated impressive stone ablation rates in our bench testing across a range of power settings. We will discuss the details of these results supporting that pulse-modulation with packets of micro-pulses are a promising technological development. (Disclaimers: Bench Test results may not necessarily be indicative of clinical performance. The testing was performed by or on behalf of BSC.
Stone retropulsion during laser lithotripsy results from various physical phenomena such as recoil momentum, bubble dynamics, and subsequent jet formation. Considerable stone retropulsion has been observed whereby the optical energy is converted into both mechanical and thermal energy as a distinctive bubble generation and collapse. It is hypothesized that by reducing the peak power and lengthening the pulse duration, we can reduce this conversion of optical energy into mechanical energy. This should maximize the thermal effects on the stone leading to enhanced ablation efficiency as well as less stone “chasing”. We are reporting on a new prototype Holmium laser with low pulse power and long temporal pulse durations in an attempt to minimize stone retropulsion.
Holmium:YAG laser is commonly used as an efficient technology for lithotripsy, breaking urinary stones into small particles (dust) and larger residual fragments (RF). One of the ultimate goals is to create fine dust for real-time aspiration, eliminating the need for mechanical retrieval of RFs. A recent study of stone dust definition suggests a maximum particle size of 250-µm to allow complete aspiration through the working channel of a flexible ureteroscope.
We have evaluated the particle size generation of a concept Holmium:YAG laser utilizing a pulse width modulation technique. This technology delivers numerous low-energy micro-pulses per pulse with long temporal pulse duration to potentially enable finer dust particles, better ablation rate, and reduced retropulsion. Overall, the concept device generates a high percentage of fine dust compared with prior results found in literature.
(Disclaimers: Bench Test results may not necessarily be indicative of clinical performance. The testing was performed by or on behalf of BSC. Data on file. Concept device or technology. Not available for sale. This device is not yet available for sale in the United States).
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