Dataset Information

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

ABSTRACT:

Introduction

With increasing use of high-power laser settings for lithotripsy, the potential exists to induce thermal tissue damage. In vitro studies have demonstrated that temperature elevation sufficient to cause thermal tissue damage can occur with certain laser and irrigation settings. The objective of this pilot study was to measure caliceal fluid temperature during high-power laser lithotripsy in an in vivo porcine model.

Methods

Four female pigs (30-35?kg) were placed under general anesthesia and positioned supine. Retrograde ureteroscopy with entry into upper or middle calices was performed. Thermocouples were placed into the calix by open exposure and puncture of the kidney or retrograde alongside the ureteroscope. A 242??m laser fiber was positioned in the center of the calix and activated (0.5?J, 80?Hz, 40?W) for 60 seconds with high, medium, or no irrigation delivered in each trial. Finite element simulations of laser-induced heating in a renal calix were also performed.

Results

Peak temperatures of 84.8°C, 63.9°C, and 43.6°C were recorded for no, medium, and high irrigation, respectively. Mean time to reach threshold of thermal injury (t₄₃ of 120 minutes) was 12.7 and 17.8 seconds for no and medium irrigation. Thermal damage thresholds were not reached in high-irrigation trials. Numerical simulations revealed similar results with peak spatial average fluid temperatures of >100°C, 58.5°C, and 37.5°C during 60 seconds of laser activation for 0.1, 15, and 40?mL/minute irrigation, respectively.

Conclusions

High-power holmium laser settings (40?W) can induce potentially injurious temperatures in the porcine in vivo model, particularly with slower irrigation rates. Characterization of thermal dose across a broader range of laser parameter settings is underway to map out the thermal safety envelope.

SUBMITTER: Aldoukhi AH

PROVIDER: S-EPMC6096348 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Publications

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

Aldoukhi Ali H AH Hall Timothy L TL Ghani Khurshid R KR Maxwell Adam D AD MacConaghy Brian B Roberts William W WW

Journal of endourology 20180713 8

<h4>Introduction</h4>With increasing use of high-power laser settings for lithotripsy, the potential exists to induce thermal tissue damage. In vitro studies have demonstrated that temperature elevation sufficient to cause thermal tissue damage can occur with certain laser and irrigation settings. The objective of this pilot study was to measure caliceal fluid temperature during high-power laser lithotripsy in an in vivo porcine model.<h4>Methods</h4>Four female pigs (30-35 kg) were placed under ...[more]

PMID: 29905092

Similar Datasets

Project description:BackgroundLaser lithotripsy (LL) is a common modality for treatment of children and adolescents with nephrolithiasis. Recent introduction of higher-powered lasers may result in more efficacious "dusting" of urinary calculi. However, in vivo animal studies and computational simulations have demonstrated rapid and sustained rise of fluid temperatures with LL, possibly resulting in irreversible tissue damage. How fluid and tissue heating during LL vary with pediatric urinary tract development, however, is unknown. We hypothesize that kidneys of younger children will be more susceptible to changes in fluid temperature and therefore tissue damage than those of older children.MethodsComputational simulations were developed for LL in children utilizing COMSOL Multiphysics finite-element modeling software. Simulation parameters were varied, including the child's age (3, 8, and 12 years), flow of irrigation fluid (gravity - 5 mL/min or continuous pressure flow - 40 mL/min), treatment location (renal pelvis, ureter, calyx), and power settings (5 W - 40 W). Using a simplified axisymmetric geometry to represent the collecting space, the model accounted for heat transfer via diffusion, convection, perfusion, and heat sourcing as well as tissue properties and blood flow of the urothelium and renal parenchyma. Laminar and heat-induced convection flow were simulated, assuming room-temperature ureteroscopic irrigation. Renal size was varied by age, based on normative values. The maximum fluid temperature after 60 s of simulated LL was captured. Thermal dose was calculated using the t43 equivalence of 240 min as a threshold for tissue damage, as was tissue volume at risk for irreversible cellular damage.ResultsSimulation with gravity flow irrigation revealed generation of thermal doses sufficient to cause tissue injury for all ages at 20 W and 40 W power settings. Higher temperatures were seen in younger ages across all power settings. Temperature increases were dampened with intermittent laser activity and continuous pressure flow irrigation.ConclusionsSmaller renal size is more susceptible to thermal changes induced by LL. However, power settings equal to or greater than 20 W can result in temperatures high enough for tissue damage at any age. Continuous pressure flow and intermittent laser activity may mitigate the potential thermal damage from high power LL.

Project description:BackgroundLithotripsy with holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the current gold standard for treating stones of the upper urinary tract (UUT). The recently introduced thulium fiber laser (TFL) has the potential to be more efficient and as safe as Ho:YAG.ObjectiveTo compare the performance and complications between Ho:YAG and TFL for UUT lithotripsy.Design setting and participantsThis was a prospective single-center study of 182 patients treated between February 2021 and February 2022. In a consecutive approach, laser lithotripsy was performed via ureteroscopy with Ho:YAG for 5 mo, and then with TFL for 5 mo.Outcome measurements and statistical analysisOur primary outcome was stone-free (SF) status at 3 mo after ureteroscopy with Ho:YAG versus TFL lithotripsy. Secondary outcomes were complication rates and results regarding the cumulative stone size. Patients were followed at 3 mo with abdominal imaging (ultrasound or computed tomography).Results and limitationsThe study cohort comprised 76 patients treated with Ho:YAG laser and 100 patients treated with TFL. Cumulative stone size was significantly higher in the TFL than in the Ho:YAG group (20.4 vs 14.8 mm; p = 0.01). SF status was similar in both groups (68.4% vs 72%; p = 0.06). Complication rates were comparable. In subgroup analysis, the SF rate was significantly higher (81.6% vs 62.5%; p = 0.04) and the operative time was shorter for stones measuring 1-2 cm, whereas the results were similar for stones <1 cm and >2 cm. The lack of randomization and single-center design are the main limitations of the study.ConclusionsTFL and Ho:YAG lithotripsy are comparable in terms of the SF rate and safety for the treatment of UUT lithiasis. According to our study, for a cumulative stone size of 1-2 cm, TFL is more effective than Ho:YAG.Patient summaryWe compared the efficiency and safety of two laser types for the treatment of stones in the upper urinary tract. We found that stone-free status at 3 months did not significantly differ between the holmium and thulium lasers.

Dataset Information

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

Introduction

Methods

Results

Conclusions

Publications

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

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