PD41-06 EFFECT OF PELVICALYCEAL FLUID VOLUME ON TEMPERATURE ELEVATION AND THERMAL DOSE DURING LASER LITHOTRIPSY

Abstract

You have accessJournal of UrologySurgical Technology & Simulation: Instrumentation & Technology II (PD41)1 Sep 2021PD41-06 EFFECT OF PELVICALYCEAL FLUID VOLUME ON TEMPERATURE ELEVATION AND THERMAL DOSE DURING LASER LITHOTRIPSY Nikta R. Khajeh, Timothy L. Hall, Khurshid R. Ghani, and William W. Roberts Nikta R. KhajehNikta R. Khajeh More articles by this author , Timothy L. HallTimothy L. Hall More articles by this author , Khurshid R. GhaniKhurshid R. Ghani More articles by this author , and William W. RobertsWilliam W. Roberts More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002051.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: While high-power holmium lasers facilitate successful ureteroscopic treatment of larger and more complex stones, they can also substantially elevate fluid temperatures in the ureter and collecting system potentially causing thermal injury of the adjacent tissue. Fluid volume is an important factor when assessing temperature elevation. The aim of this study was to investigate temperature elevation and thermal dose from laser lithotripsy in model calyces/pelvises spanning a clinically relevant range of fluid volumes. METHODS: Glass bulbs of volumes 0.5, 2.8, 4.0, 7.0, 21.0, and 60.8 mL served as calyx/pelvis models. A single bulb was submerged in a tank of 37˚C deionized (DI) water to simulate core body temperature. A 230 µm core laser fiber extending 5 mm from the tip of a LithoVue ureteroscope was positioned in the center of the model. Irrigation settings of 0, 8, 15, and 40 ml/min with room temperature DI water were used while a P120 Ho:YAG laser was activated for 60 seconds at 40W (0.5 J x 80 Hz, SP). Temperature was measured every second by a thermocouple affixed 5 mm from the tip of the ureteroscope. 5 trials were run under each parameter. Thermal dose was calculated from the temperature curves using the Dewey and Sapareto t43 methodology with t43=120 equivalent minutes accepted as the threshold for thermal injury. RESULTS: The rate of temperature elevation and thermal dose from laser activation were inversely proportional to the volume of fluid in each model and the irrigation rate. The time to threshold for thermal injury was only 3 seconds for the smallest model (0.5 ml) without irrigation, while it was never reached in the largest model (60.8 mL), regardless of irrigation rate (table). 40 ml/min irrigation maintained safe temperatures below the threshold for injury in all models (figure). CONCLUSIONS: Clinicians should be mindful when using high power laser settings in confined calyxes, or tight spaces as heating of small volume fluid to dangerous levels can occur quickly. Source of Funding: Research grant from Boston Scientific © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e682-e683 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Nikta R. Khajeh More articles by this author Timothy L. Hall More articles by this author Khurshid R. Ghani More articles by this author William W. Roberts More articles by this author Expand All Advertisement Loading ...