At what airway pressure does the lower inflection point occur?

The lower inflection point, often referred to as the "lower inflection point of the pressure-volume curve," represents the pressure at which the recruitment of collapsed or fluid-filled alveoli begins to occur. This is significant in mechanical ventilation because it indicates the transition between an area of minimal compliance and an area where the compliance of the lung improves significantly with increasing pressure.

In practice, a lower inflection point set at 10 cmH2O corresponds to the point where adequate lung inflation begins, allowing for improved gas exchange and ventilation efficiency with less risk of ventilator-induced lung injury. Setting the airway pressure above this threshold helps ensure that alveoli are adequately expanded, maximizing ventilation.

This understanding is pivotal in managing patients who may have conditions like Acute Respiratory Distress Syndrome (ARDS) where lung mechanics change significantly and require careful titration of airway pressures. The choice of 10 cmH2O for this inflection point reflects a common observation in clinical practice and aligns with outcomes aimed at improving oxygenation while minimizing barotrauma.