Presented by: Anna Ricapito MD
Icahn School of Medicine at Mount Sinai

Introduction

Currently, pulse modulated high power holmium:yttrium-aluminum-garnet (Ho:YAG) and superpulsed thulium fiber laser (TFL) are the two laser systems routinely used in kidney stone surgery. However, to date, there have been no head-to-head randomized controlled trials comparing efficacy for solely renal stone lithotripsy. To this end, we aimed to compare the stone free rates, intraoperative efficiency, and complication rates of the two leading contemporary laser systems used in retrograde intrarenal surgery (RIRS).

Materials

This is an on-going prospective randomized trial of patients undergoing single stage unilateral RIRS with preoperative computed tomography (CT) proven renal stones between 5 and 20 mm. Patients with ureteral stones were excluded. Patients were then randomized to either Ho:YAG or TFL group after undergoing anesthesia. Laser settings, energy output, and lasing time, were recorded intraoperatively. Patients were followed post-operatively to determine complication rates and ED visits. Primary outcome was stone-free rate which was evaluated by CT scan at 6 weeks postoperatively. Two different definitions of stone-free rate were used: category A was defined as zero residual fragments and category B defined as no fragments greater than ≥ 3 mm. Secondary outcomes included laser efficiency (laser energy used per unit volume of stone) laser activity (laser-on time per total lithotripsy time) and fragmentation speed (volume of stone fragmented per second) and postoperative complications. Categorical variables were compared between groups using Chi-square of Fisher’s exact tests while continuous variables were analyzed using Mann-Whitney U-tests.

Results

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27 patients were randomized to Ho:YAG (n = 14) or TFL (n = 13) groups. Category A stone-free rates were 71.4% and 61.5% for Ho:YAG  and TFL respectively (p=.695). Category B stone-free rates were 92.9% and 61.5% for Ho:YAG  and TFL respectively (p=.077). Total energy used (2.54 vs. 1.98 kJ, p=0.734), lasering time (9.90 vs. 7.25 min, p=0.489), lithotripsy time (19.5 vs. 16 min, p=0.587), operative time (52.5 vs. 66 min, p=.645) were similar. Laser efficiency (23.18 vs. 12.96 kJ/mm³, p=0.228), laser activity (53% vs. 40%, p=.448), and fragmentation speed (.19 vs. .25 mm³/s, p=0.293) did not differ in Ho:YAG vs. TFL respectively. ED visits (7.1% vs. 7.7%, p=1.0) and Clavien complications (0% vs. 7.7%, p= .481) were similar between groups. There were no readmissions for either group.

Conclusion

Our preliminary data did not show significant differences in any clinically relevant domain, including stone-free rates, intraoperative efficiency measures, or postoperative complications when comparing Ho:YAG and TFL during RIRS for renal stones. In light of the data, laser choice should be left to surgeon’s preference.

Funding

None

Co-Authors

Alan J. Yaghoubian, MD
Icahn School of Medicine at Mount Sinai

Anna Ricapito, MD
University of Foggia, Department of Urology

Christopher Connors, BS
Icahn School of Medicine at Mount Sinai

Samuel Yim, BS
SUNY Downstate Health Sciences University

Blair Gallante, MPH
Icahn School of Medicine at Mount Sinai

Johnathan A. Khusid, MD
Icahn School of Medicine at Mount Sinai

William M. Atallah, MD, MPH
Icahn School of Medicine at Mount Sinai

Mantu Gupta, MD, FRCS
Icahn School of Medicine at Mount Sinai