Temperature profiles during ureteroscopy with thulium fiber laser and holmium:YAG laser: Findings from a pre-clinical study

Abstract

Objective: The aim of this study was to investigate temperature profiles in both the renal pelvis and parenchyma during Thulium Fiber Laser (TFL) and Holmium:yttrium-aluminium-garnet (Ho:YAG) laser activation in an ex-vivo porcine model. Methods: Three porcine kidneys with intact renal pelvis and proximal ureters were used in the study. A temperature sensor was inserted through a nephrostomy tube into the renal pelvis and a second sensor was inserted directly into the renal parenchyma. Temperatures were recorded during continuous laser activation for 180 s, and for an additional 60 s after deactivation. TFL (150 lm and 200 lm) and Ho:YAG (270 lm) laser delivered power at settings of 2.4 W, 8 W, 20 W and 30 W. Results: Intrapelvic temperatures correlated directly to power settings. Higher power produced higher temperatures. For example, using a 150 lm fiber at 2.4 W resulted in a 2.6 C rise from baseline (p ¼ 0.008), whereas using the same fiber at 20 W produced a rise in temperature of 19.9 C (p ¼ 0.02). Larger laser fibers caused significantly higher temperatures compared to smaller fibers using equivalent power settings, e.g. mean temperature at 20 W using 150 lm was 39.6 C compared to 44.9 C using 200 lm, p < 0.001. There was a significant increase in parenchymal temperatures when applying 20 W and 30 W of laser power with the two larger fibers. Conclusion:In this ex-vivo study, renal temperatures correlated directly to power settings. Higher power produced higher temperatures. Furthermore, larger laser fibers caused higher temperatures. These findings could help guide selection of safe power settings for ureteroscopic lithotripsy, but future clinical studies are needed for confirmation.

Retrograde intra renal surgery and safety: pressure and temperature. A systematic review

“…This study is not consistent with two cadaveric and one living porcine experiments that demonstrated similar increase in temperature using whether TFL or Ho:YAG at similar settings [39 ▪▪ ,40,41]. Increasing the laser fiber diameter was associated with a higher temperature at a similar power setting [39 ▪▪ ,42].…”

“…An in vitro study reported higher temperature with TFL at the same settings without difference in the required time to reach average or maximum intra-ureteral temperatures between any laser system at all power settings tested [38]. This study is not consistent with two cadaveric and one living porcine experiments that demonstrated similar increase in temperature using whether TFL or Ho:YAG at similar settings [39 ▪▪ ,40,41]. Increasing the laser fiber diameter was associated with a higher temperature at a similar power setting [39 ▪▪ ,42].…”

“…Regarding the laser settings, the available data show low power settings (<30 W) to provide safe IRT and the same efficiency than high power settings (>30W), with minimal irrigation flow [45,46,53,59,60]. Furthermore, the laser source doesn’t influence the IRT increase, at similar settings [39 ▪▪ ]. Burst laser lithotripsy with high frequencies (>30 Hz) with ODC >50% are suggested to increase IRT and thermal dose whereas low power-low frequencies and continuous activation do not expose to thermal damage [56].…”

Lasers for stone lithotripsy: advantages/disadvantages of each laser source

“…Concerns regarding intrarenal temperature with the use of HP have raised [35][36][37] and more studies are needed to find the limits to avoid the potential damage [38][39] especially when treating ureteral stones [40][41][42]. For this issue, temperature sensors have been proposed [43].…”

Ureteroscopy during pregnancy under local anesthesia and light sedation: Technique and video

“…[ 4 ] To this end, a small laser fiber should be selected, as this helps to maximize the irrigation flow available and keeps temperatures low. [ 5 ] The surgeon is required to perform instrumentation with additional care when the patient is awake. Unintentional contact between the activated laser and the ureteral wall causes unwanted discomfort.…”