Category: Clinical Stones: Ureteroscopy

MP29-12 - The Rise and Fall of Dangerous Temperature Changes During Ureteroscopic Laser Lithotripsy

Sun, Sep 23
2:00 PM - 4:00 PM

Introduction & Objective :

Temperatures (Ts) over 43°C - the threshold for cellular death – may be achieved during ureteroscopic holmium laser lithotripsy. While prior studies have shown the importance of irrigation during laser activation, the time to reach and subsequently clear dangerous Ts across common irrigation pressures has not been studied.


Methods :

A flexible ureteroscope (Lithovue) or a short Olympus semirigid (SR) ureteroscope was placed within a 36cm 13 Fr ureteral access sheath inserted into a full 250cc minibag of saline to simulate a normal caliber ureter, renal pelvis reservoir effect, and antegrade flow of urine. We placed a thermocouple 1mm adjacent to the tip of a 365μm laser fiber that we fired for 45sec at 0.6 J/6 Hz, 0.8 J/8 Hz, 1 J/10 Hz, 0.2J/80Hz and 1 J/20 Hz. We tested, irrigation pressures of 200, 100, and 0mmHg. At each pressure, two runs per laser setting were recorded. The mean T change (TΔ) was recorded with 6°C above baseline as a threshold (as body temperature is 6°C below the 43°C mark).


Results :

SR group: At 200mmHg there was no mean TΔ >6°C. At 100mmHg >6° of TΔ was seen only at 1J/20Hz after 1sec of activation and returned to ≤6° within 1sec. With 0mmHg of pressure, TΔ >6° was seen at all laser settings and occurred as quickly as 1sec when power was ≥10W. The 0.2J/80Hz tests were halted early due to boiling. T returned to ≤6°C within 5sec in all but 0.2J/80Hz, which took 10sec (Fig A-C). 


Flexible group: At 200mmHg, TΔ >6°C occurred with 1J/10Hz (15sec), .2J/80Hz (3sec), and 1J/20Hz (2sec). Ts returned to ≤6° of baseline within 2sec for each setting. At 100mmHg, TΔ >6C° occurred in all but .6J/6Hz and .8J/8Hz; Ts returned to ≤6°C in 10sec with .2J/80Hz and 1J/20Hz while .8J/8Hz and 1J/10Hz took 3 and 4sec, respectively. At 0mmHg, all settings surpassed TΔ >6°C within 3sec, except .6J/6Hz (35sec). Ts returned to ≤6°C in 10sec for 1J/10Hz and .2J/80Hz and 1sec with .6J/6Hz (Fig D-F).


Conclusions :

Potentially dangerous intraureteral Ts were achieved in our in vitro model in as little as 1 second at common irrigation pressures, particularly with laser settings ≥10W. However, these high Ts returned to a safe level within seconds at each irrigation pressure and in the SR group.

Russell S. Terry

Endourology Fellow
Duke University Medical Center, Division of Urology
Durham, North Carolina

Fellow in Endourology, Metabolic Stone Disease, Laparoscopy, and Robotic Surgery
Division of Urologic Surgery
Duke University Medical Center

Brenton B. Winship

Endourology Fellow
Duke University Medical Center, Division of Urology
Durham, North Carolina

Daniel Wollin

Durham, North Carolina

Evan Carlos

Durham, North Carolina

Chloe Peters

Durham, North Carolina

Jingqiu Li

Singapore, Not Applicable, Singapore

Glenn M. Preminger

Duke University Medical Center, Division of Urology
Durham, North Carolina

Michael E. Lipkin

Associate Professor Urology
Duke University Medical Center, Division of Urology
Durham, North Carolina