Minimally invasive percutaneous nephrolithotomy with SuperPulsed Thulium-fiber laser

Abstract

We aimed to assess the efficacy and safety of minimally invasive percutaneous nephrolithotomy (PCNL) with SuperPulsed Thulium-fiber laser (SP TFL) using different frequency settings. 125 patients with solitary kidney calculi of up to 55 mm in the maximum diameter underwent mini-PCNL with the SP TFL. Stone-free rate, laser-on time, ablation efficacy, energy consumption, ablation speed and complications were all analyzed. Negative low-dose computed tomography scan or asymptomatic patients with stone fragments < 2 mm were the criteria for assessing the stone-free status. In 36 patients (28.8%) low frequency regimens were used (LF: 3-19 Hz-0.5-6 J), in 75 patients (60%) high frequency regimens were chosen (HF: 20-49 Hz-0.2-2 J) and in 14 (11.2%) patients higher frequency (HRF: 50-200 Hz-0.1-0.5 J) regimens were preferred. The mean age was 52 ± 1.8 years. Median stone diameter and median stone volume were larger at low frequency regimens compared to high frequency regimens. Ablation efficacy (J/mm³) was lower at low rather than at high frequency regimens. Ablation speed (mm³/sec) was higher at low compared to high frequency regimens. Surgeons reported minimal and absent retropulsion at higher frequency regimens. The best visibility was observed at high frequency regimens. The overall stone free rate (SFR) at 3 months was 85%. The majority of the postoperative complications were classified between Clavien grades I-II. SP TFL is an effective and safe tool for performing mini-PCNL regardless of the laser settings.

Keywords: Kidney; Percutaneous nephrolithotomy; Thulium fiber laser; Urinary stones; Urolithiasis.