Pulmonary Ultrasound for the Assessment of Atelectasis in Anesthetized Children Using a Laryngeal Mask Airway: a Randomized Double-Blinded Controlled Trial That Compares Spontaneous and Pressure Support Ventilation

It is well known and described the deleterious effect that general anesthesia (GA) has on functional residual capacity (FRC), especially in children. This population is at higher risk of decreasing FRC during GA because of their lower capacity for elastic retraction and lower relaxation volume comparing to adults, predisposing them to the development of atelectasis and airway closure. These factors will lead to intrapulmonary shunts, which may impair the gas exchange and consequently oxygenation. By reducing the intrapulmonary shunt, Positive End Expiratory Pressure (PEEP) during controlled mechanical ventilation in patients with healthy lungs optimizes the FRC. However, the available data for an optimal ventilation strategy, including optimal PEEP, using a laryngeal mask airway (LMA) in the pediatric population are scarce, even though this device is frequently used in all age groups for brief general anesthesia.

Diagnosing anesthesia-induced atelectasis in the perioperative period can be possible by using lung ultrasounds (LUS), a simple, easily accessible, non-invasive and radiation free technique, which might help determine the impact in pulmonary aeration between different ventilation strategies. In our study, we will focus on comparing spontaneous ventilation (VS) with a PEEP of 5 cmH2O and pressure-support ventilation using a LMA in anesthetized children undergoing minor and elective outpatient surgery.