Positive End-Expiratory Pressure

The purpose of this multicenter, randomized controlled trial (ULTRASVENT-2) is to evaluate the effect of different positive end-expiratory pressure (PEEP) levels on postoperative oxygenation and lung aeration in adult patients undergoing elective non-cardiac and non-thoracic surgery under general anesthesia. Moving away from traditional binary outcomes, this study utilizes a continuous functional metric, the non-invasive oxygenation index SpO2/FiO2 (S/F ratio), as the primary endpoint to precisely capture the degree of respiratory function preservation. Patients will be stratified into four distinct surgical cohorts based on the type and aggressiveness of the procedure: non-abdominal surgery, major open abdominal surgery, major laparoscopic abdominal surgery, and low-trauma laparoscopic surgery. This adaptive design aims to investigate how protective PEEP strategies interact with varying degrees of surgical trauma and intraoperative pneumoperitoneum, allowing the optimization of mechanical ventilation parameters for routine clinical practice.

Acute respiratory distress syndrome (ARDS) remains a serious and often fatal complication in patients following severe trauma or major surgery. Mechanical ventilation is essential for supportive care in this population, but may aggravate lung injury when suboptimal ventilatory settings are applied. Positive end-expiratory pressure (PEEP) is crucial for maintaining alveolar recruitment; however, optimal PEEP selection in trauma- or postoperative-associated ARDS remains uncertain. Electrical impedance tomography (EIT) enables bedside, real-time assessment of regional ventilation and may support optimal PEEP titration by balancing alveolar overdistension and collapse. This study compares EIT-guided PEEP optimization with the conventional low FiO₂-PEEP strategy in terms of oxygenation and respiratory mechanics in patients with moderate to severe ARDS following trauma or surgery.

Abdominal laparoscopy is widely utilized due to its benefits, including minimal invasiveness, improved cosmetic outcomes, and shorter hospital stays. However, the use of intraoperative pneumoperitoneum and general anesthesia with mechanical ventilation may lead to postoperative pulmonary complications, such as atelectasis. This condition can result in diminished respiratory mechanics and impaired gas exchange. In recent years, intraoperative lung-protective mechanical ventilation techniques, including recruitment maneuvers (RMs) and positive end-expiratory pressure (PEEP) strategies, have gained popularity. These approaches aim to prevent the repeated collapse and reopening of alveoli, thereby reducing the risk of atelectasis. Nonetheless, determining the optimal PEEP level for individual patients remains a complicated and unresolved issue. Electrical impedance tomography (EIT) is a bedside imaging technique that assesses regional ventilation distribution, providing a method for personalizing PEEP settings in mechanically ventilated patients. By addressing the competing risks of alveolar overdistension and collapse, EIT enhances the precision of PEEP titration. This study aims to compare the effects of recruitment maneuvers and EIT-guided PEEP selection against conventional ventilation on regional ventilation, gas exchange, and pulmonary mechanics in patients undergoing abdominal laparoscopic surgery.

Acute respiratory distress syndrome (ARDS) in its moderate to severe forms is associated with high mortality. Mechanical ventilation (MV) remains the cornerstone of ARDS management but carries a significant risk of ventilator-induced lung injury (VILI). Positive end-expiratory pressure (PEEP), a fundamental component of MV, is widely utilized in clinical practice; however, optimal PEEP selection for patients with moderate to severe ARDS remains a complex and unresolved challenge. Electrical impedance tomography (EIT), a bedside imaging modality that evaluates regional ventilation distribution, offers a means of individualizing PEEP settings in mechanically ventilated patients. By balancing the competing risks of alveolar overdistension and collapse, EIT facilitates precision in PEEP titration. This study compares the impact of EIT-guided PEEP selection versus the conventional low FiO2-PEEP table on blood oxygenation and pulmonary mechanics.

Acute Respiratory distress syndrome (ARDS) is a severe condition in which protective ventilation is a critical point in its management. Positive end expiratory pressure (PEEP) setting can be challenging for clinicians and high PEEP has been associated with better outcome in moderate and severe ARDS. Recently, recruitment to inflation ratio and airway closure have been investigated in order to help PEEP adjustment. However, ventilatory maneuvers are performed with a low level of PEEP and therefore expose to derecruitment and oxygen desaturation. So far, the risk of oxygen desaturation has not been investigated and risk factors are unknown. The aim of this study is to evaluate the prevalence of oxygen desaturation during ventilatory maneuvers at low level of PEEP in patients with moderate or severe ARDS