Alveolar Tipping Points in Changing Lungs Related to Positive End-expiratory Pressure

The fundamental principles of respiratory physiology and lung behavior during mechanical ventilation are well established. However, the effects of lung injury on respiratory structure and function leading to significant heterogeneity among different regions of the lungs are still only partially understood. Even more challenging are state changes, such as regions of the lungs switching from being ventilated to collapsed. Remarkably, these state changes of atelectatic regions involve critical pressures for opening and closing, similar to tipping points (fig. 1A) in other complex systems, e.g., tipping points in asthma leading to “catastrophic” regional airway constriction and ventilation defects.^1,2  Additionally, it is a significant challenge to characterize these tipping points.³ 

Grieco et al.⁴  show now in a study tracking the end- expiratory lung volume and lung mechanics during decremental positive end-expiratory pressure (PEEP) trials in moderate-to-severe COVID-19 acute respiratory distress syndrome that the degree...