This prospective observational cohort study aims to evaluate the predictive value of perioperative lung ultrasound (LUS) score in determining early postoperative oxygen requirement and pulmonary complications in patients undergoing major non-thoracic surgery. Postoperative pulmonary complications remain a significant cause of morbidity and mortality in surgical patients. Lung ultrasound is a non-invasive, bedside imaging modality that allows real-time assessment of lung aeration and pathology. This study will investigate the association between perioperative LUS score and early postoperative respiratory outcomes, including oxygen requirement and pulmonary complications.

Postoperative pulmonary complications are among the most common causes of postoperative morbidity and prolonged hospital stay following major surgery. Early identification of patients at risk is crucial for timely intervention and improved outcomes. Lung ultrasound (LUS) has emerged as a reliable, non-invasive, and bedside tool for evaluating lung aeration and detecting pulmonary abnormalities such as atelectasis, interstitial syndrome, and pleural effusion.

This prospective observational cohort study is designed to assess the predictive value of perioperative lung ultrasound score in patients undergoing major non-thoracic surgery. A total of 97 patients aged between 18 and 65 years will be included. Lung ultrasound examinations will be performed perioperatively, and LUS scores will be calculated based on standardized protocols.

The primary objective of this study is to evaluate the relationship between perioperative LUS score and early postoperative oxygen requirement. Secondary objectives include assessing the association between LUS score and the incidence of postoperative pulmonary complications, need for intensive care unit admission, and length of hospital stay.

By identifying the predictive role of lung ultrasound scoring, this study aims to contribute to improved perioperative risk stratification and support the use of lung ultrasound as a practical tool in routine anesthetic and surgical care.

Inclusion Criteria:

• Aged 18 to 65 years
• Scheduled for elective major non-thoracic surgery
• Undergoing surgery under general anesthesia
• Expected surgical duration of 3 hours or longer
• ASA physical status I-III
• Willing to participate in the study
• Provides written informed consent

Exclusion Criteria:

• Patients undergoing thoracic or cardiac surgery
• Advanced chronic lung disease (e.g., severe COPD or pulmonary fibrosis)
• History of previous lung resection
• Preoperative pneumonia or active pulmonary infection
• Body mass index greater than or equal to 40 kg/m2
• Pregnancy
• Emergency surgery
• Planned postoperative mechanical ventilation or intensive care unit admission
• Refusal to participate in the study

Adult patients aged 18 to 65 years undergoing elective major non-thoracic surgery under general anesthesia with an expected surgical duration of 3 hours or longer at Dicle University Faculty of Medicine Hospital.

Individual participant data will not be shared due to institutional policies and ethical considerations regarding patient confidentiality.