Assessment of intrarenal temperature dynamics when using holmium and thulium: YAG lasers in an ex vivo porcine kidney model.

AIM: To measure the temperature dynamics at the renal surface and within the urinary tract when using Ho:YAG and Tm:YAG lasers for tissue ablation. MATERIALS AND METHODS: Porcine kidneys were used. Both types of lasers with different configurations and fiber sizes were used through a flexible ureteroscope. The temperature at the renal surface was recorded using a thermal camera while the intrarenal temperature was measured using two thermal probes, the first one at the ureteropelvic junction and the second one at the calyx used for lasering. Temperature was determined at 0.5-1-3-5 and 10 min. RESULTS: Recordings at the ureteropelvic junction and calyx revealed significant increases when using Tm:YAG with the 273 µm (10 W to 50 W) (p ≤ 0.02) and 550 µm (10 W) fiber (p = 0.04). With Ho:YAG there was a significant increase when using 273 µm (at 10 W and 20 W) (p ≤ 0.03) and 365 µm (10 W) fibers (p = 0.04). Regarding fiber size there was a significant difference when using Tm:YAG (at 20 W and 40 W) (p < 0.05). The thermal camera recorded a mean increase of 8 °C in the UPJ while the remaining areas of the kidney did not undergo significant changes. CONCLUSIONS: Temperature changes were greater when using the Ho:YAG laser with respect to Tm:YAG at similar power settings for tissue ablation. The greatest temperature increase was recorded at the UPJ from where the heat dissipated throughout the kidney.