The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy

Winship, Brenton; Wollin, Daniel; Carlos, Evan; Peters, Chloe E.; Li, Jingqiu; Terry, Russell; Boydston, Kohldon; Preminger, Glenn M.; Lipkin, Michael

doi:10.1089/end.2019.0084

Cited by 69 publications

(38 citation statements)

References 16 publications

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“…Numerous studies have confirmed that significant temperature rise can occur around the fiber. Once, the temperature exceeds the "threshold" (43°C), it can lead to cell damage, protein coagulation and tissue injury [13], which subsequentially progresses to scar formation and ureteral stricture. According to the relationship of the tissue thermal damage and temperature, for every 1°C exceeds the threshold temperature, the time required to cause damage to the same number of cells will decrease by half [14].…”

Section: Discussionmentioning

confidence: 99%

Thermal effect of holmium laser during ureteroscopic lithotripsy

Liang¹,

Liang²,

Yu³

et al. 2020

BMC Urol

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Background: Holmium laser lithotripsy is the most common technique for the management of ureteral stone. Studies founded that holmium laser firing can produce heat which will cause thermal injury towards ureter. The aim of our current study is to explore factors affecting thermal effect of holmium laser during ureteroscopic lithotripsy. Methods: An in vitro experimental model is design to simulate the ureteroscopic lithotripsy procedure. Different laser power settings (10w (0.5JX20Hz, 1.0 JX10Hz), 20w (1.0 JX20Hz, 2.0 JX10Hz), 30w (1.5JX20Hz, 3.0 JX10Hz)) with various firing time (3 s, 5 s, 10s) and irrigation flow rates(10 ml/min, 15 ml/min, 20 ml/min and 30 ml/min) were employed in the experiment. The temperature around the laser tip was recorded by thermometer. Results: The temperature in the "ureter" rises significantly with the increasing laser power, prolonging firing time and reducing irrigation flow. The highest regional temperature is 78.0°C at the experimental setup , and the lowest temperature is 23.5°C. Higher frequency setting produces more heat at the same power. Laser power < =10w, irrigation flow> = 30 ml/min and "high-energy with low-frequency" can permit a safe working temperature. Conclusion: We clarify that the thermal effect of holmium laser is related with both laser working parameters and irrigation flow. The proper setting is the key factor to ensure the safety during ureteroscopic holmium laser lithotripsy.

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Section: Discussionmentioning

confidence: 99%

Thermal effect of holmium laser during ureteroscopic lithotripsy

Liang¹,

Liang²,

Yu³

et al. 2020

BMC Urol

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“…This can result in excessive temperature elevation of the fluid within the collecting system as demonstrated in a number of in vitro and in vivo studies, as well as computer simulations. [1][2][3][4][5][6][7][8][9] Many of the published studies assessing risk of thermal injury were designed with continuous laser activation of 1 minute or longer. This standardization is useful for scientific analysis and comparability between studies, but it is not directly applicable to clinical patterns of laser activation.…”

Section: Introductionmentioning

confidence: 99%

Patterns of Laser Activation During Ureteroscopic Lithotripsy: Effects on Caliceal Fluid Temperature and Thermal Dose

Aldoukhi

Dau

Majdalany

et al. 2021

Journal of Endourology

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Introduction: Characterizing patterns of laser activation is important for assessing thermal dose during laser lithotripsy. The objective of this study was twofold: first, to quantify the range of operator duty cycle (ODC) and pedal activation time during clinical laser lithotripsy procedures, and second, to determine thermal dose in an in vitro caliceal model when 1200 J of energy was applied with different patterns of 50% ODC for 60 seconds. Methods: Data from laser logs of ureteroscopy cases performed over a 3-month period were used to calculate ODC (lasing time/lithotripsy time). Temporal and rolling 1-minute average power tracings were generated for each case. In vitro experiments were conducted using a 21 mm diameter glass bulb in a 37°C water bath, simulating a renal calix. A LithoVue ureteroscope with attached thermocouple was inserted and 8 mL/min irrigation was delivered with a 242 lm laser fiber within the working channel. In total, 1200 J of laser energy was applied in five different patterns at 20 W average power for 60 seconds. Thermal dose was calculated using the Sapareto and Dewey t 43 method. Results: A total of 63 clinical cases were included in the analysis. Mean ODC was 32% overall and 63% during the 1-minute of greatest energy delivery. Mean time of pedal activation was 3.6 seconds. In vitro studies revealed longer pedal activation times produced higher peak temperature and thermal dose. Thermal injury threshold was reached in 9 seconds when 40 W was applied at 50% ODC with laser activation patterns of 30 seconds on/off and 15 seconds on/off. Conclusion: ODC was quantified from clinical laser lithotripsy cases: 32% overall and 63% during 1-minute of peak power. Time of pedal activation is an important factor contributing to fluid heating and thermal dose. Awareness of these concepts is necessary to reduce risk of thermal injury during laser lithotripsy procedures.

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“…The dependency of temperatures on the combination of frequency, pulse duration, and single pulse energy has been extensively investigated and revealed inconsistencies. [18][19][20][21][22][23][24][25] For example, most of these studies did not use a energy meter, thus the actual laser power output was not considered as a source of deviation. In addition, several studies use passive irrigation and do not measure the flow rate.…”

Section: Discussionmentioning

confidence: 99%

“…As a consequence of the increasing laser powers, interest has grown in recent years regarding the temperatures generated during laser lithotripsy. [18][19][20][21][22][23][24][25] In clinical practice, irrigation is used to improve visibility and cool down the surrounding fluid; therefore, if irrigation is insufficient or absent, tissue-damaging temperatures may be reached within a short time. 24,25 As a means to limit tissue damage, the cumulative equivalent minutes at 43°C (CEM 43 ) value was defined, which corresponds to the cumulative time equivalent at 43°C.…”

Section: Introductionmentioning

confidence: 99%

Temperature Assessment of a Novel Pulsed Thulium Solid-State Laser Compared with a Holmium:Yttrium-Aluminum-Garnet Laser

Petzold

Suarez-Ibarrola

Miernik

2021

Journal of Endourology

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Purpose: To compare a novel Thulium laser device with the commonly used Holmium:Yttrium-Aluminum-Garnet (Ho:YAG) laser in terms of the in vitro temperatures generated. Methods: Our study investigated and compared an evaluation model of a solid-state Thulium laser with a Medilas H Solvo 35 Holmium laser device, both by Dornier (Dornier MedTech Laser GmbH, Wessling, Germany). Our in vitro model consisted of a 20 mL test tube placed in a 37°C water bath. Constant irrigation was set at 50 mL/minute with a Reglo Z Digital pump (Cole Parmer, Chicago, IL). Four hundred micrometers of Dornier laser fibers were used. The temperature was measured with a type K thermocouple and a real-time data logger from Pico (PICO Technology, Cambridgeshire, United Kingdom). Power settings between 2 and 30 W were investigated. Each measurement lasted 120 seconds and was repeated five times. The data were evaluated by MATLAB Ò (The Mathworks, Inc., Natick, MA). Results: The resulting temperatures were directly proportional to the power supplied. When comparing Holmium with Thulium, we observed maximum deviations of £0.82 K in temperatures at 120 seconds. The highest investigated laser power of 30 W yielded maximum temperatures differing by 6.7 K from the initial value. Out of the five comparisons, Thulium showed marginally yet significantly lower end temperatures in four cases and slightly lower cumulative equivalent minutes at 43°C (CEM 43) values in three cases. Conclusion: The Thulium laser resembles the Holmium device in the temperatures generated during in vitro application. An increase in laser power, thus, leads to equivalent increases in temperature that are largely independent of frequency, pulse duration, and single pulse energy. Pulsed Thulium:Yttrium-Aluminum-Garnet (Tm:YAG), Ho:YAG, and Thulium fiber laser seem to share a similar risk profile for patients in terms of temperature development. Intrarenal power outputs exceeding 10 W during clinical application should be compensated by ensuring sufficient irrigation.

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The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy

Cited by 69 publications

References 16 publications

Thermal effect of holmium laser during ureteroscopic lithotripsy

Thermal effect of holmium laser during ureteroscopic lithotripsy

Patterns of Laser Activation During Ureteroscopic Lithotripsy: Effects on Caliceal Fluid Temperature and Thermal Dose

Temperature Assessment of a Novel Pulsed Thulium Solid-State Laser Compared with a Holmium:Yttrium-Aluminum-Garnet Laser

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