Pneumoperitoneum and Trendelenburg positioning during laparoscopic surgery promote atelectasis development, which has been reported in up to 90% of patients under general anesthesia and increases the risk of postoperative pulmonary complications. High-flow nasal cannula (HFNC) oxygen therapy may reduce post-extubation atelectasis through alveolar recruitment. This prospective observational cohort study aims to evaluate the role of HFNC in postoperative atelectasis monitored by lung ultrasonography (LUS) in patients undergoing elective laparoscopic surgery.