Airway closure in infants with acute bronchiolitis on mechanical ventilation
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2025
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Background: The pathophysiology of acute bronchiolitis is thought to be explained by the classical mechanism of distal airway obstruction by debris and mucus plugs. However, the alterations in respiratory mechanics described in previous studies suggest that other mechanisms may be involved. Airway closure is a phenomenon mainly characterized by the cyclic collapse of the distal airways, leading to alveolar air trapping, denitrogenation atelectasis, and bronchiolar inflammation. This study aimed to determine whether airway closure is present in patients with severe acute bronchiolitis. Methods: Prospective and observational study in a tertiary-care pediatric intensive care unit at a general hospital in Infants with acute bronchiolitis under mechanical ventilation. We identified the presence of airway closure through a quasistatic pressure-volume curve obtained from a pneumotachometer with a proximal flow sensor. Our findings were corroborated by simultaneously acquiring a pressure-impedance curve and ventilation maps using electrical impedance tomography. Results: Airway closure was confirmed in 7 out of 12 patients with a median airway opening pressure of 14 cmH2O (IQR 11-16). Patients with airway closure exhibited high levels of driving pressure, with a median of 16 cmH2O (IQR 11-17) and low levels of respiratory system compliance, with a median of 0.41 ml/cmH2O/kg (IQR 0.38-0.59). When these parameters were corrected for airway opening pressure, there was a significant decrease in driving pressure, with a median of 9 cmH2O (IQR 9-13), p = 0.027, and a significant increase in respiratory system compliance, with a median of 0.63 ml/cmH2O/kg (IQR 0.51-0.81), p = 0.028. Conclusions: Airway closure is common in ventilated infants with acute bronchiolitis, and its assessment may play a significant role in interpreting respiratory mechanics.
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Tesis (Magíster en Investigación en Ciencias de la Salud)--Pontificia Universidad Católica de Chile, 2025