Between October 2025 and December 2025, Patients who underwent fURS surgery in our clinic, with the surgical indication determined according to the EAU guidelines, were included in the study. Patients over 18 years of age with unilateral, single stones located in the upper or middle calyx or in the renal pelvis were included in the study. Patients with chronic obstructive pulmonary disease, pregnancy, a history of abdominal, retroperitoneal, or thoracic surgery, kidney anomalies, or stones located in the lower calyx were excluded.

Respiratory parameter measured:

Tidal Volume (mL/kg)

Measurement tool: Anaesthesia ventilator/monitoring system

Unit: milliliters per kilogram (mL/kg)

Surgical outcomes assessed:

Stone-free rate (%), assessed by postoperative non-contrast CT scan

Operative time (minutes), recorded from surgical logs

Complications, graded using the Clavien-Dindo classification

The objective is to determine the statistical correlation between tidal volume and each of these surgical outcomes.

Operative time (minutes), recorded from surgical logs

Surgical efficiency (stone volume / operative time, mm³/min)

Laser time (seconds), recorded from laser console

Laser energy used (Joules), recorded from laser console

Lasing efficiency (stone volume / lasing time, mm³/sec)

Complications, graded using the Clavien-Dindo classification

Bleeding rate (%), incidence of significant intra- or postoperative bleeding

Infection rate (%), incidence of postoperative urinary tract infection

Length of hospital stay (days), total postoperative hospitalization