This study is an observational clinical investigation designed to evaluate perioperative lung aeration in adult patients undergoing elective laparoscopic cholecystectomy under general anesthesia. The primary objective is to assess lung status using lung ultrasound in patients aged 18 to 65 years.

A total of 80 volunteer participants will be enrolled. Lung aeration will be evaluated using lung ultrasound scoring before and after surgery. Patient demographic characteristics, medical history, intraoperative airway pressure values, and perioperative lung ultrasound scores will be recorded for analysis.

This study is conducted solely for research purposes and does not involve any drug intervention. All patients will receive standard perioperative care as determined by their attending anesthesiologist and surgical team, with no deviation from routine clinical practice. Participation is voluntary, and patients may withdraw from the study at any time without affecting their medical care.

Perioperative atelectasis is a frequent consequence of general anesthesia and represents a major contributor to postoperative pulmonary complications. Anesthesia-induced loss of functional residual capacity, impaired diaphragmatic movement, and altered ventilation-perfusion matching predispose dependent lung regions to alveolar collapse. These effects are further amplified during laparoscopic surgery due to pneumoperitoneum-induced increases in intra-abdominal pressure, patient positioning, and the routine use of high fractions of inspired oxygen. Even in patients without preexisting pulmonary disease, these factors may result in clinically significant atelectasis during and after surgery.

Laparoscopic cholecystectomy is one of the most commonly performed minimally invasive surgical procedures and serves as a standardized clinical model to investigate perioperative respiratory strategies. Pneumoperitoneum and reverse Trendelenburg positioning during this procedure lead to cephalad displacement of the diaphragm, reduced lung compliance, and regional ventilation heterogeneity, thereby increasing the risk of perioperative atelectasis.

Alveolar recruitment maneuvers are ventilation strategies aimed at reopening collapsed alveoli by temporarily increasing transpulmonary pressure. When applied appropriately, recruitment maneuvers may improve lung aeration, enhance oxygenation, and increase respiratory system compliance. Several studies have demonstrated the beneficial effects of recruitment maneuvers during laparoscopic surgery; however, the optimal timing of these maneuvers remains controversial. The period immediately before extubation is particularly vulnerable to lung derecruitment, and applying a recruitment maneuver at this time may help restore lung aeration and reduce early postoperative atelectasis.

Lung ultrasound has emerged as a reliable, noninvasive, and bedside imaging modality for the assessment of lung aeration. The Lung Ultrasound Score (LUS) allows semi-quantitative evaluation of aeration loss by systematically examining predefined thoracic regions. LUS has been validated against computed tomography and has demonstrated high sensitivity in detecting perioperative atelectasis, making it well suited for use in the intraoperative and immediate postoperative period.

In this prospective clinical study, adult patients scheduled for elective laparoscopic cholecystectomy under general anesthesia will be evaluated to determine the effect of an alveolar recruitment maneuver applied immediately before extubation on perioperative atelectasis. Lung aeration will be assessed using lung ultrasound at predefined time points, and changes in the Lung Ultrasound Score will be used as the primary indicator of atelectasis. Secondary outcomes will include oxygenation parameters and basic respiratory variables.

This study aims to provide objective ultrasound-based evidence regarding the effectiveness of pre-extubation recruitment maneuvers in reducing perioperative atelectasis. The findings may contribute to the optimization of lung-protective ventilation strategies in routine anesthetic practice and support the integration of lung ultrasound into perioperative respiratory monitoring.

Inclusion Criteria:

• Adult patients scheduled for elective laparoscopic cholecystectomy under general anesthesia
• Age between 18 and 65 years
• Body mass index (BMI) < 30 kg/m²
• American Society of Anesthesiologists (ASA) physical status classification I-III
• Provision of written informed consent

Exclusion Criteria:

• Refusal to participate in the study
• Emergency surgical procedures
• Body mass index (BMI) ≥ 30 kg/m²
• American Society of Anesthesiologists (ASA) physical status classification IV

The study population consists of adult patients aged 18 to 65 years who are scheduled to undergo elective laparoscopic cholecystectomy under general anesthesia. Eligible participants have a body mass index below 30 kg/m² and are classified as American Society of Anesthesiologists (ASA) physical status I-III. All participants provide written informed consent prior to enrollment. Patients undergoing emergency surgery or with significant comorbidities requiring ASA physical status IV are excluded.

Individual participant data will not be shared.

The baseline analysis population was identical to the population assigned to the study groups in the participant flow.

From anesthesia induction through hospital discharge (approximately 3-5 days postoperatively)

Adverse events were monitored from the time of anesthesia induction until hospital discharge. All respiratory complications and events requiring intervention were recorded.

Single-center design limits generalizability. Study was unblinded due to the nature of ventilation protocols. Lung ultrasound scoring may have inter-observer variability despite standardized training. Long-term outcomes beyond hospital discharge were not assessed.