Patients who are intubated and mechanically ventilated in the intensive care unit (ICU) require repeated endotracheal suctioning to remove airway secretions. Although this procedure is necessary, it can cause a temporary collapse of lung units (alveolar derecruitment), leading to a decrease in lung volume and impaired oxygenation.

A recruitment maneuver consists of briefly applying a higher airway pressure after suctioning in order to reopen collapsed lung areas and restore lung volume. However, the clinical benefit of performing a recruitment maneuver systematically after suctioning remains uncertain.

This study aims to evaluate whether performing a recruitment maneuver immediately after closed-circuit endotracheal suctioning improves lung volume compared with suctioning alone. Lung volume will be assessed using electrical impedance tomography (EIT), a non-invasive bedside imaging technique that allows real-time monitoring of lung aeration.

In a randomized crossover design, each patient will undergo two suctioning procedures: one followed by a recruitment maneuver and one without, in a random order. The main outcome will be the change in end-expiratory lung volume 15 minutes after suctioning. The results may help optimize ventilatory care in mechanically ventilated ICU patients.

Endotracheal suctioning in mechanically ventilated ICU patients is a common procedure but is associated with alveolar derecruitment, resulting in a decrease in end-expiratory lung volume (EELV), deterioration of oxygenation, and potential lung injury.

A recruitment maneuver applied immediately after suctioning may reopen collapsed alveoli and restore lung volume, provided that sufficient positive end-expiratory pressure is maintained. However, available data are limited and conflicting, especially in adult ICU patients.

This prospective, randomized, open-label, single-center crossover trial will evaluate the physiological impact of a recruitment maneuver performed after closed-circuit endotracheal suctioning.

Each patient will receive two interventions in random order:

• Treatment A: closed-circuit endotracheal suctioning alone
• Treatment B: closed-circuit endotracheal suctioning followed immediately by a recruitment maneuver (airway pressure 30 cmH₂O for 30 seconds, with unchanged PEEP) Patients will be randomized to one of two sequences (AB or BA), with a 15-minute washout period between interventions.

Electrical impedance tomography (PulmoVista® V500) will be used to measure end-expiratory lung impedance, which reflects EELV. Functional residual capacity will be measured using nitrogen washout on a CARESCAPE R860 ventilator. Lung compliance and PaO₂/FiO₂ ratio will also be recorded.

Measurements will be obtained before suctioning and 15 minutes after each intervention. The primary endpoint is the percentage change in EELV at 15 minutes after suctioning between the two conditions.

A total of 32 mechanically ventilated ICU patients will be included.

Inclusion Criteria:

• Adults aged ≥18 years
• Covered by national health insurance
• Admitted to the intensive care unit
• Intubated and mechanically ventilated
• Neuromuscular blockade at inclusion
• Written informed consent obtained from a legally authorized representative or next of kin

Exclusion Criteria:

• Contraindication to electrical impedance tomography (e.g. pacemaker, implantable cardioverter-defibrillator, or implanted electrical stimulation device)
• Contraindication to recruitment maneuvers (e.g. emphysema, undrained pneumothorax, hemodynamic instability)
• Refractory intracranial hypertension
• Acute respiratory distress syndrome requiring prone positioning
• Pregnant or breastfeeding women
• Patients deprived of liberty or under legal protection
• Any condition judged by the investigator to interfere with study evaluation