Tissue thermal effect during lithotripsy and tissue ablation in endourology: a systematic review of experimental studies comparing Holmium and Thulium lasers.

PURPOSE: We looked into the Thulium: yttrium-aluminum-garnet (TM:YAG), Thulium Fibre laser (TFL) and Holmium: yttrium-aluminum-garnet (Ho:YAG) thermal laser tissue effect during lithotripsy and tissue ablation. METHODS: We performed a PubMed, Scopus, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) search. RESULTS: During lithotripsy, the Ho:YAG generated temperatures from 24 to 68.7 °C at powers < 20 W, the Tm:YAG from 43.7 °C at 30 W to 68 °C at powers < 20 W, and the TFL from 33 to 40.46 °C. During ablation, the Ho:YAG and continuous wave (cw) Tm:YAG tissue incision depths ranged from 0.08 to 2.26 mm, and from 0.28 to 3.22 mm. The Ho:YAG and Tm:YAG vaporization areas ranged from 0.044 to 0.078 mm2 and from 0.050 to 0.078 mm3 and their coagulation zones were 0.075 mm2 and 0.125 mm3 respectively. Ho:YAG and Tm:YAG laser damage zones ranged from 0.093 to 2.6 mm3 and from 0.207 to 0.98 mm3 respectively. The TFL incision depth ranged from 0.04 to 5.7 mm. The cw and SuperPulsed (SP) vaporization volumes ranged from 8 to 28.2 mm3/s and from 4 to 11 mm3/s. TFL coagulation depth and coagulation zone ranged from zero to 1.1 mm, 2.2 to 5.1 mm3 in SP mode and from 7.7 to 18.1 mm3 in cw mode. CONCLUSION: During lithotripsy all lasers caused similar temperature changes and had a safe temperature profile at < 40 W. During tissue ablation, Ho:YAG has a deeper incision depth, while cwTm:YAG and cwTFL have broader coagulation and total laser areas.