Diaphragmatic Excursion Changes and Postoperative Oxygenation After Laparoscopic Cholecystectomy

Inclusion Criteria: * Adults aged 18-75 years * Scheduled for elective laparoscopic cholecystectomy under general anesthesia * Able to undergo diaphragm ultrasonography (no preoperative barrier to assessment) * Able to cooperate with preoperative and early postoperative diaphragm measurements * Postoperative oxygenation data available (SpO₂, FiO₂, and SpO₂/FiO₂ can be recorded) * Provided written informed consent Exclusion Criteria: * Morbid obesity (BMI ≥ 40 kg/m²) * Known diaphragmatic paralysis, phrenic nerve injury, or hemidiaphragm dysfunction * Severe COPD, restrictive lung disease, or advanced parenchymal lung disease * Preoperative home oxygen therapy or CPAP/BiPAP/home mechanical ventilation * Conversion to open surgery (laparoscopic → open) * Hemodynamic instability preoperatively or intraoperatively; emergency/complicated surgery * Factors preventing ultrasound assessment (e.g., marked upper abdominal gas, large scar/wound, severe subcutaneous edema) * Same-day discharge cases with \<24-hour observation * Inability to complete measurements (e.g., severe cognitive impairment, poor cooperation, severe pain preventing measurement) * Incomplete data not compatible with the protocol