Comparison of temperature and renal tissue thermal damage by Holmium laser with different energy parameters during lithotripsy: in vitro porcine kidney model

Abstract OBJECTIVE The holmium laser percutaneous nephrolithotripsy was simulated by porcine kidney calculus model in vitro to investigate the thermal damage of renal tissue by holmium laser with different energy parameters. METHODS We placed human kidney calculus specimen in a fresh vitro porcine kidney, then insert thermocouple temperature probes into the submucosa of the renal pelvis and rewarmed in a 37°C water bath. The renal parenchyma was penetrated with a percutaneous nephrological sheath through moderate irrigation rate of 30 ml/s in 18℃, and the Holmium laser was used to fragment the stone under the nephroscope and record the temperature. RESULTS The four independent models were lithotripsy with 30W and 60W laser for 5 and 10 minutes, respectively; the mean temperature of 30W vs. 60W within 5 minutes was 36.06°C vs. 39.21°C (t = 5.36, P = 0.00) and the highest temperature was 43.60°C vs. 46.60°C; the mean temperature of 30W vs. 60W within 10 minutes was 37.91°C vs. 40.13 ℃ (t = 5.28, P = 0.00), maximum temperature 46.80℃ vs. 49.20℃. Pathologically, each kidney was observed to have different degrees of thermal injury lesions, and the higher the power and longer the time the more severe the injury, but the injury was mainly limited to the uroepithelial and subepithelial tissues, with rare damage to the renal tubules, etc. Conclusion The higher power and longer time of holmium laser excitation will raise the intrarenal temperature significantly and cause a certain degree of thermal damage to the kidney tissue, but overall it is safe and reliable, and urologists can avoid more side damage through surgical experience skills.