Neonates With Tracheomalacia Generate Auto-Positive End-Expiratory Pressure via Glottis Closure

Abstract Background In pediatrics, tracheomalacia is an airway condition that causes tracheal lumen collapse during breathing and may lead to the patient requiring respiratory support. Adult subjects can narrow their glottis in order to self-generate positive end-expiratory pressure (auto-PEEP) to raise the pressure in the trachea and prevent collapse. However, auto-PEEP has not been studied in newborns with tracheomalacia. The objective of this study is to measure the glottis cross-sectional area throughout the breathing cycle and to quantify total pressure difference through the glottis in subjects with and without tracheomalacia. Research Question Do neonates with tracheomalacia narrow their glottises? How does the glottis narrowing affect the total pressure along the airway? Study Design and Methods Ultrashort echo time magnetic resonance imaging (MRI) was performed in 21 neonatal intensive care unit subjects (11 tracheomalacia, 10 non-tracheomalacia). MR images were reconstructed at 4 different phases of breathing. All subjects were breathing room air or using non-invasive respiratory support at the time of MRI. Computational fluid dynamics simulations were performed on patient-specific virtual airway models with airway anatomy and motion derived via MRI to quantify the total pressure difference through the glottis and trachea. Results The mean glottis cross-sectional area at peak expiration in the subjects with tracheomalacia was less than half that in subjects without tracheomalacia (4.0 ± 1.1 mm2 vs. 10.3 ± 4.4 mm2, p = 0.002). The mean total pressure difference through the glottis at peak expiration was more than ten times higher in subjects with tracheomalacia compared to subjects without tracheomalacia (2.88 ± 2.29 cmH2O vs. 0.26 ± 0.16 cmH2O, p = 0.005). Interpretation Neonates with tracheomalacia narrow their glottises, which raises pressure in the trachea during expiration, thereby acting as auto-PEEP.