This prospective randomized clinical trial aims to evaluate the effects of different fresh gas flow rates on postoperative pulmonary aeration using lung ultrasonography in patients undergoing elective laparoscopic cholecystectomy. Patients will be randomly assigned to receive either low-flow anesthesia (0.5 L/min) or high-flow anesthesia (4 L/min) during maintenance of general anesthesia. The primary objective is to compare postoperative lung ultrasound scores and the incidence of atelectasis between the two groups.