Patients with obstructive sleep apnea syndrome are at higher risk for respiratory complications after surgery. Oxygen depletion and respiratory distress are common in patients with obstructive sleep apnea syndrome. In this study, the effectiveness of the recruitment maneuver applied in the postoperative period will be investigated via lung ultrasound. Recruitment is a technique performed to improve the oxygen levels of patients. Patients diagnosed with obstructive sleep apnea syndrome between the ages of 18-65 will be included in the study and anesthesia and surgical procedures will be followed. The aim of the study is to compare the pulmonary complication rates between patients who underwent recruitment and those who did not, and to examine the effects of factors such as age and gender on these complications via lung ultrasound.

The effect of the recruitment maneuver applied in the postoperative period on lung ventilation and atelectasis will be investigated via lung ultrasound. Recruitment is a technique performed to improve the oxygen levels of patients. Patients diagnosed with obstructive sleep apnea between the ages of 18-65 will be included in the study. The aim of the study is to compare atelectasis rates, pleural fascial fluid accumulation, lung compliance, pneumothorax findings between patients who underwent and did not undergo recruitment with lung ultrasound. In addition, to examine the effects of factors such as age and gender on these complications with lung ultrasound. Our study is a prospective, single-center, control group clinical trial to be conducted on patients diagnosed with obstructive sleep apnea syndrome (OSA). Patients between the ages of 18-65, classified as American Society of Anesthesia I-III, and diagnosed with Obstructive Sleep Apnea (polysomnography or STOP-BANG score ≥3) will be included in the study. Written informed consent will be obtained from the patients before the surgical procedure. Patients to be excluded from the study will include American Society of Anesthesia class IV and above patients, those with a history of neuromuscular disease, patients requiring cardiac surgery, and patients requiring urgent surgical intervention.

Patients will be randomly divided into three groups by computer-based program: Group 1: A fixed 5 cmH2O post expiratory positive end-expiratory pressure will be applied. Group 2: In addition to the fixed positive end-expiratory pressure, a recruitment maneuver will be performed at the end of surgery before extubation by giving 6 breaths with a tidal volume at 2 times the vital capacity, an inspiration/expiration ratio of 1/1, and a lung plateau pressure of < 35 cmH2O. Group 3: In addition to the fixed positive end-expiratory pressure, a recruitment maneuver will be performed at the end of surgery by giving 6 breaths in the right and left lateral decubitus positions before extubation. All patients' preoperative demographic data, apnea device usage, chest X-ray, total anesthesia duration, surgical duration, drugs used and their doses, ventilation parameters (tidal volume, positive end-expiratory pressure, airway peak pressure), fluid balance, surgical procedure type, patient position data will be recorded. Hemodynamic parameters, oxygen, respiratory exercise and bronchodilator requirements of patients taken to the recovery unit will be recorded. Lung A line and B line scores will be evaluated separately as 8 zones while performing lung ultrasonography of all patients. Plasm points, air bronchogram findings, pleural sliding movements will be recorded for each zone. In these follow-ups, saturation, hemodynamic parameters, respiratory exercise, bronchodilator requirement, intubation requirement, unplanned intensive care admission, hospital stay duration will also be recorded.

Inclusion Criteria:

• Patients aged 18-65
• American Society of Anesthesia I-III
• Patients with consent to participate
• Patients with preoperative OSA diagnosis (polysomnography or STOP-BANG≥3)

Exclusion Criteria:

• American Society of Anesthesia >IV
• Patients planned for postoperative intensive care follow-up 3. Cardiac surgery
• Anesthesia outside the operating room
• History of neuromuscular disease
• Emergency surgical application
• Invasive airway surgeries (pharynx, larynx)
• Lung surgeries (pneumonectomy, lobectomy, etc.) 9. Presence of pregnancy

After participants are enrolled and informed consent is obtained, they will be randomly assigned to one of three groups in a 1:1:1 ratio using a computer-generated randomization list prepared by an independent anesthesiologist who is not involved in the intervention. Allocation concealment will be ensured using sequentially numbered, opaque, sealed envelopes for each patient. To maintain double blinding, both the patients and the researchers responsible for postoperative evaluations (including those performing lung ultrasound and clinical follow-ups) will remain unaware of group assignments. The intraoperative team responsible for performing the intervention will only carry out the assigned procedure and will not be involved in data collection, evaluation, or analysis. Group assignments will be documented separately and kept confidential until the study is completed and data analysis is finalized.