Ex vivo study of Ho:YAG and thulium fiber lasers for soft tissue surgery: which laser for which case?

Abstract

The goal of this study was to assess the ablation, coagulation, and carbonization characteristics of the holmium:YAG (Ho:YAG) laser and thulium fiber lasers (TFL). The Ho:YAG laser (100 W av.power), the quasi-continuous (QCW) TFL (120 W av.power), and the SuperPulsed (SP) TFL (50 W av.power) were compared on a non-frozen porcine kidney. To control the cutting speed (2 or 5 mm/s), an XY translation stage was used. The Ho:YAG was tested using E = 1.5 J and P av = 40 W or P av = 70 W settings. The TFL was tested using E = 1.5 J and P av = 30 W or P av = 60 W settings. After ex vivo incision, histological analysis was performed in order to estimate thermal damage. At 40 W, the Ho:YAG displayed a shallower cutting at 2 and 5 mm/s (1.1 ± 0.2 mm and 0.5 ± 0.2 mm, respectively) with virtually zero coagulation. While at 70 W, the minimal coagulation depth measured 0.1 ± 0.1 mm. The incisions demonstrated zero carbonization. Both the QCW and SP TFL did show effective cutting at all speeds (2.1 ± 0.2 mm and 1.3 ± 0.2 mm, respectively, at 30 W) with prominent coagulation (0.6 ± 0.1 mm and 0.4 ± 0.1 mm, respectively, at 70 W) and carbonization. Our study introduced the TFL as a novel efficient alternative for soft tissue surgery to the Ho:YAG laser. The SP TFL offers a Ho:YAG-like incision, while QCW TFL allows for fast, deep, and precise cutting with increased carbonization.

Lasers for benign prostatic hyperplasia (hybrid, blue diode, TFL, Moses). Which one to choose?

“…Thus, the tissue penetration depth is 0.2 mm. In vitro studies reported higher incision and coagulation depths in continuous wave mode in comparison to the pulsed one [20][21][22]. At the same power output, a pronounced carbonization was reported in continuous wave mode.…”

Laser Fiber Displacement Velocity during Tm-Fiber and Ho:YAG Laser Lithotripsy: Introducing the Concept of Optimal Displacement Velocity

“…As a potential consequence to the longer pulse duration, the morphology and the duration of the induced vapor channel created at the fiber tip could participate in the smaller ODV for Tm-Fiber [ 5 ]. If the mechanism of stone ablation associates photothermal and mechanical effects, the induced vapor bubbles take parts in both mechanisms [ 19 , 20 , 21 ]. A longer (duration and size) and wider bubble flow may be responsible for a greater ablated volume in a precise location, thereby reducing the ODV, according to our definition.…”

Thulium fiber laser in urology: physics made simple

“…Continuous temperature increases above 60 o C and above the boiling point lead to tissue ablation/vaporization [7]. A further increase in temperature leads to the onset of pyrolysis, which eventually terminates in carbonization [18].…”