Caliceal Fluid Temperature During High-Power Holmium Laser Lithotripsy in an <i>In Vivo</i> Porcine Model

Aldoukhi, Ali H.; Hall, Timothy L.; Ghani, Khurshid R.; Maxwell, Adam D.; MacConaghy, Brian; Roberts, William W.

doi:10.1089/end.2018.0395

Cited by 122 publications

(58 citation statements)

References 14 publications

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“…Reducing the frequency and, therefore, the total power during lithotripsy is of importance to limit the risk of thermal injury from heat generation. 26,27 In conclusion, the results of this in vitro study demonstrated that there is a frequency threshold after which increasing the pulse frequency leads to minimal gain in ablation when the laser fiber is fixed. When the fiber is moving, increasing the frequency increases fragmentation, but also only until a specific higher frequency threshold is reached.…”

Section: Figmentioning

confidence: 61%

Frequency Threshold for Ablation During Holmium Laser Lithotripsy: How High Can You Go?

Aldoukhi

Black

Hall

et al. 2020

Journal of Endourology

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Purpose: We performed in vitro studies to assess the relationship of pulse frequency on stone ablation during contact laser lithotripsy and determine if there is a threshold after which its effect on lithotripsy is limited. Methods: BegoStones were fragmented using a Ho:YAG laser (P120 Moses) and a 230 lm fiber at 0.5 J on long pulse (LP) and Moses distance (MD) modes in contact with the stone. The relationship between the number of pulses (1-40 Hz) on stone crater volume was assessed using three-dimensional confocal microscopy and nonlinear-segmented regression. To simulate a painting technique, we assessed fragmentation (mg/second) at 20, 40, and 60 Hz, with the fiber moving at a speed of 1 and 3 mm/second, respectively. High-speed imaging was used to record ablation. Results: When the laser fiber was fixed, after 13.0 (LP) and 15.4 (MD) pulses, greater pulse frequency did not lead to a significant increase in stone crater volume. Fragmentation was greatest at higher frequencies and faster fiber speed. Increasing the frequency from 20 to 60 Hz at 3 mm/second increased fragmentation by 82% and 61% for LP and MD modes, respectively. Using high-speed data, if the laser fiber is moving at 1 mm/second, a hypothetical frequency threshold for ablation was calculated to be 52 and 61.6 Hz for LP and MD modes, respectively. Conclusion: Increasing the fiber speed increases stone ablation when using high frequency settings. When the fiber is fixed there is a threshold after which increasing the pulse frequency leads to minimal gain in ablation. The exact value for threshold when the fiber is moving needs further study. Our study serves to provide insight for parameter selection and safety of laser lithotripsy for dusting technique.

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Section: Figmentioning

confidence: 61%

Frequency Threshold for Ablation During Holmium Laser Lithotripsy: How High Can You Go?

Aldoukhi

Black

Hall

et al. 2020

Journal of Endourology

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“…Innovations in laser development resulted in the introduction of high power Ho:YAG lasers on the market, providing an average power around 100W, which can be very efficient in stone destruction [35][36][37]. Furthermore, attention should in particular also be dedicated to heat generation inside the urinary tract when using such high power laser devices [38][39][40][41][42]. Fluorescence-assisted endoscopic laser lithotripsy should be introduced in particular in connection with high power laser devices.…”

Section: Propulsiomentioning

confidence: 99%

Holmium:yttrium-aluminum-garnet laser induced lithotripsy: in-vitro investigations on fragmentation, dusting, propulsion and fluorescence

Eisel

Ströbl

Pongratz

et al. 2018

Biomed. Opt. Express

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The fragmentation efficiency on Bego artificial stones during lithotripsy and the propulsive effect (via video tracking) was investigated for a variety of laser settings. A variation of the laser settings (pulse energy, pulse duration, repetition rate) altered the total application time required for stone fragmentation, the stone break up time, and the propulsion. The obtained results can be used to develop lithotripsy devices providing an optimal combination of low stone propulsion and high fragmentation efficacy, which can then be evaluated in a clinical setting. Additionally, the fluorescence of human kidney stones was inspected endoscopically in vivo. Fluorescence light can be used to detect stone-free areas or to clearly distinguish calculi from surrounding tissue or operation tools.

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“…As this wavelength is so strongly absorbed by water, it can damage the surrounding tissue. While severe direct physical lesions occur seldom, there is increasing evidence that secondary thermal injuries due to excessive temperatures in the upper urinary tract can become dangerous [6][7][8]. The Ho:YAG laser's therapeutic range in aqueous liquid is about 1-5 mm, and the release of high energetic pulses depends solely on the surgeon.…”

Section: Introductionmentioning

confidence: 99%

Laser-guided real-time automatic target identification for endoscopic stone lithotripsy: a two-arm in vivo porcine comparison study

et al. 2020

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Introduction and objective Thermal injuries associated with Holmium laser lithotripsy of the urinary tract are an underestimated problem in stone therapy. Surgical precision relies exclusively on visual target identification when applying laser energy for stone disintegration. This study evaluates a laser system that enables target identification automatically during bladder stone lithotripsy, URS, and PCNL in a porcine animal model. Methods Holmium laser lithotripsy was performed on two domestic pigs by an experienced endourology surgeon in vivo. Human stone fragments (4–6 mm) were inserted in both ureters, renal pelvises, and bladders. Ho:YAG laser lithotripsy was conducted as a two-arm comparison study, evaluating the target identification system against common lithotripsy. We assessed the ureters’ lesions according to PULS and the other locations descriptively. Post-mortem nephroureterectomy and cystectomy specimens were examined by a pathologist. Results The sufficient disintegration of stone samples was achieved in both setups. Endoscopic examination revealed numerous lesions in the urinary tract after the commercial Holmium laser system. The extent of lesions with the feedback system was semi-quantitatively and qualitatively lower. The energy applied was significantly less, with a mean reduction of more than 30% (URS 27.1%, PCNL 52.2%, bladder stone lithotripsy 17.1%). Pathology examination revealed only superficial lesions in both animals. There was no evidence of organ perforation in either study arm. Conclusions Our study provides proof-of-concept for a laser system enabling automatic real-time target identification during lithotripsy on human urinary stones. Further studies in humans are necessary, and to objectively quantify this new system’s advantages, investigations involving a large number of cases are mandatory.

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Caliceal Fluid Temperature During High-Power Holmium Laser Lithotripsy in an In Vivo Porcine Model

Cited by 122 publications

References 14 publications

Frequency Threshold for Ablation During Holmium Laser Lithotripsy: How High Can You Go?

Frequency Threshold for Ablation During Holmium Laser Lithotripsy: How High Can You Go?

Holmium:yttrium-aluminum-garnet laser induced lithotripsy: in-vitro investigations on fragmentation, dusting, propulsion and fluorescence

Laser-guided real-time automatic target identification for endoscopic stone lithotripsy: a two-arm in vivo porcine comparison study

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