OBJECTIVE: The risk of thermal damage increases with the introduction of high-power lasers during holmium laser lithotripsy. This study aimed to quantitatively evaluate the temperature change of renal calyx in the human body and the 3D printed model during high-power flexible ureteroscopic holmium laser lithotripsy and map out the temperature curve.
METHODS: The temperature was continuously measured by a medical temperature sensor secured to a flexible ureteroscope. Between December 2021 and December 2022, willing patients with kidney stones undergoing flexible ureteroscopic holmium laser lithotripsy were enrolled. High frequency and high-power settings (24 W, 80 Hz/0.3 J and 32 W, 80 Hz/0.4 J) were performed for each patient with room temperature (25 °C) irrigation. In the 3D printed model, we studied more holmium laser settings (24 W, 80 Hz/0.3 J, 32 W, 80 Hz/0.4 J and 40 W, 80 Hz/0.4 J) with warmed (37 °C) and room temperature (25 °C) irrigation.
RESULTS: Twenty-two patients were enrolled in our study. With 30 ml/min or 60 ml/min irrigation, the local temperature of the renal calyx did not reach 43 °C in any patient under 25 °C irrigation after 60 s laser activation. There were similar temperature changes in the 3D printed model with the human body under the irrigation of 25 °C. Under the irrigation of 37 °C, the temperature rise slowed down, but the temperature in the renal calyces was close to or even exceeded the 43 °C at the setting of 32 W, 30 ml/min and 40 W, 30 ml/min after continuing laser activation.
CONCLUSIONS: In the irrigation of 60 ml/min, the temperature in the renal calyces can still be maintained within a safe range after continuous activation of a holmium laser up to 40 W. However, continuous activation of 32 W or higher power holmium laser in the renal calyces for more than 60 s in the limited irrigation of 30 ml/min can cause excessive local temperature, in such situation room temperature perfusion at 25 ℃ may be a relatively safer option.

BACKGROUND: Treatment of broncholithiasis is complex, especially in the case of a large or transbronchial broncholith. Holmium-yttrium aluminum garnet (Ho:YAG) laser lithotripsy may be a useful treatment in broncholithiasis; however, as it is not yet common practice, the optimal parameters are unknown.
METHODS: We performed a single-center retrospective analysis of the clinical data of 13 broncholithiasis patients who underwent Ho:YAG laser lithotripsy from May 2012 to October 2018.
RESULTS: For the 13 patients (2 males and 11 females), Ho:YAG laser lithotripsy was performed 17 times, in total. All procedures were performed under general anesthesia with rigid bronchoscopy. We initially set the Ho:YAG laser to a pulse frequency of 5 Hz and a pulse energy of 0.8 J, gradually increasing these as required. The pulse frequency range we employed was 5-15 Hz, and the pulse energy range was 0.8-1.6 J. All broncholiths were successfully extracted after lithotripsy, and all symptoms improved. Hemoptysis, bronchial esophageal fistula, and pneumonia were the most common complications; however, there were no long-term complications.
CONCLUSIONS: Ho:YAG laser lithotripsy is an effective and safe treatment for broncholithiasis, over a long-term follow up.

OBJECTIVE: To evaluate calyceal irrigation fluid temperature changes during flexible ureteroscopic Ho:YAG laser lithotripsy.
METHODS: Between May 2019 and January 2020, patients with kidney stones undergoing flexible ureteroscopic Ho:YAG laser lithotripsy were enrolled. A K-type thermocouple was applied for intraoperative temperature measurement. Laser was activated at different power (1 J/20 Hz and 0.5 J/20 Hz) and irrigation (0 ml/min, 15 ml/min and 30 ml/min) settings, temperature-time curve was drawn and time needed to reach 43 °C without irrigation was documented.
RESULTS: Thirty-two patients were enrolled in our study. The temperature-time curve revealed a quick temperature increase followed by a plateau. With 15 ml/min or 30 ml/min irrigation, 43 °C was not reached after 60 s laser activation at both 1 J/20 Hz and 0.5 J/20 Hz. At the power setting of 1 J/20 Hz and irrigation flow rate of 15 ml/min, the temperature rise was significantly higher than other groups. Without irrigation, the time needed to reach 43 °C at 1 J/20 Hz was significantly shorter than that at 0.5 J/20 Hz (8.84 ± 1.41 s vs. 13.71 ± 1.53 s).
CONCLUSIONS: Ho:YAG laser lithotripsy can induce significant temperature rise in calyceal fluid. With sufficient irrigation, temperatures can be limited so that a toxic thermal dose is not reached, when irrigation is closed, the temperature increased sharply and reached 43 °C in a few seconds.

OBJECTIVE: To evaluate effects of holmium:yttrium-aluminum-garnet (Ho:YAG) laser ablation on postoperative low back pain and improving functional status in patients with lumbar disc herniation undergoing transforaminal endoscopic lumbar discectomy (TELD).
METHODS: The study enrolled 220 patients with lumbar disc herniation who underwent TELD or TELD with Ho:YAG laser from August 2015 to September 2016. Parameters including operative time, hospitalization, complications, and recurrence were recorded. Clinical outcomes were assessed according to visual analog scale for back pain and leg pain, Oswestry Disability Index for functional status, and modified MacNab criteria for patient satisfaction.
RESULTS: Minimal 2-year follow-up was completed by 186 patients: 76 patients who underwent TELD and 110 patients who underwent TELD with Ho:YAG laser. In the group undergoing TELD, clinical outcomes of back pain and functional status exhibited a V-shaped upward trend after surgery; there were no statistically significant differences in visual analog scale for back pain and Oswestry Disability Index scores at final follow-up compared with preoperatively (P > 0.05). In the group undergoing TELD with Ho:YAG laser, postoperative visual analog scale for back pain and Oswestry Disability Index scores significantly improved compared with preoperatively (P < 0.05) exhibiting relatively consistent improvement after surgery. The only laser-related complication was a burning sensation in the ipsilateral lower limb during the thermal procedure in 2 cases.
CONCLUSIONS: Performing Ho:YAG laser ablation with TELD prolonged low back pain relief and improved functional outcome during 2-year follow-up compared with TELD alone in patients with symptomatic lumbar disc herniation.

OBJECTIVE: To evaluate the clinical outcomes with a Chinese single-use fiberoptic flexible ureteroscope (YouCare Tech) from a prospective database.
METHODS: A prospective study was conducted in a single center in China between January 2016 and October 2017. All consecutive patients who underwent flexible ureteroscopy performed by YouCare flexible ureteroscope were analyzed. Patients\' demographics, clinical characteristics, intraoperative parameters, postoperative complications, and stone-free rate were evaluated and recorded. Stone-free status was defined as no visible stones or clinically insignificant residual stones < 2 mm on a postoperative image study.
RESULTS: A total of 684 procedures were performed for 653 patients (31 patients had bilateral stones). A double J stent had been previously placed in 431 patients. The location of the calculi was upper calyx, middle calyx, lower calyx, and renal pelvis and proximal ureter in 74, 101, 211, 115, and 183 patients, respectively. The median operative time was 52 min. The postoperative stone-free rate for the first 2 weeks after surgery was 78.5%, which increased to 91.1% at the first month. The overall stone-free rate was 95.2%. The complication rate was minor and short-term, such as gross hematuria or flank pain.
CONCLUSIONS: YouCare flexible ureteroscope can be considered effective and safe in the treatment of both upper ureteral and renal stones in selected patients. Further evaluation of comparison with other FURS\'s surgical outcomes and cost-effectiveness analysis will help to present the best utility of this single-use FURS in clinical practice.