Lung cancer is a common disease, and more than 8,000 patients in France undergo lobectomy or pulmonary segmentectomy each year. This surgery remains associated with significant postoperative pulmonary complications, whose incidence ranges from 15% to 49% depending on the study (1). The main complication is pulmonary atelectasis, which provides a favorable setting for the development of postoperative pneumonia.

In thoracic surgery, the operated lung is excluded, and one-lung ventilation is performed on the contralateral lung. During surgery, several strategies exist to prevent atelectasis during one-lung ventilation, known as protective ventilation strategies (2). At the end of the procedure, reventilation allows re-expansion of the previously excluded lung.

However, pulmonary reventilation induces the release of pro-inflammatory cytokines and causes endothelial dysfunction, which may lead to pulmonary edema, thereby negating the benefits of intraoperative protective ventilation. Conversely, insufficient re-expansion may result in persistent postoperative atelectasis, whereas excessive re-expansion can cause volutrauma, alveolar trauma, and/or barotrauma to the operated lung (3).

Several reventilation techniques are currently used, but to our knowledge, the impact of reventilation itself has never been specifically studied. The first, empirical technique, consists of reventilating both lungs using the accessory circuit and the adjustable pressure-limiting (APL) valve, manually bagging the patient over several respiratory cycles (4). The main drawback of this method is the lack of monitoring of insufflated volumes and pressures.

The second, more recent technique, consists of reventilating the patient using the anesthesia machine circuit in controlled ventilation mode, which allows for precise monitoring of pressures and insufflated volumes (5). This approach provides real-time monitoring of lung re-expansion and could therefore be less harmful than the empirical method.

Thus, the objective of this study is to compare postoperative pulmonary complications between patients who underwent lung re-expansion using the accessory circuit and those who underwent lung re-expansion using the anesthesia machine circuit in controlled ventilation mode.

Inclusion Criteria:

• ASA score ≤ 3.
• Undergoing a scheduled video-assisted or robot-assisted lobectomy or segmentectomy.
• Patient has read and understood the information sheet and signed the informed consent form.
• For women of childbearing potential, effective contraception and confirmation of the absence of an ongoing pregnancy by a negative blood or urine pregnancy test are required.
• Postmenopausal women (spontaneous, non-medically induced amenorrhea for at least 12 months prior to the inclusion visit).
• Patient affiliated with a social security system.

Exclusion Criteria:

• Patients with a BMI > 40 kg/m².
• Patients with severe chronic respiratory failure (COPD grade 3, FEV₁/FVC < 0.7 and FEV₁ < 50% - according to the GOLD 2025 classification).
• Patients with severe chronic renal failure (GFR < 30 mL/min).
• Patients at high risk of conversion to thoracotomy.
• Patients with a history of acute respiratory distress syndrome (ARDS) within 3 months prior to surgery.
• Patients with a known history of severe hepatic failure (Child-Pugh class B or C).
• Patients with a history of heart failure (NYHA class ≥ II).
• Patients with a history of pulmonary resection.
• Patients with uncontrolled asthma.
• Pregnant or breastfeeding women.
• Patients deprived of liberty by administrative or judicial decision, as well as those under legal protection, guardianship, or curatorship.