Figure 4

An alternative technique to assess recruitment: automatic analysis of the pressure–time curve. Illustration of the concept proposed by Ranieri and colleagues to monitor recruitment and overdistension during tidal normal breaths. A mathematical equation allows one to analyze the aspect of the inspiratory part of the airway pressure tracing during a breath obtained with a constant inspiratory flow. A concave downward shape of the pressure–time curve reflects continuous recruitment (left panel) while a convex downward shape indicates overdistension (right panel) The straight shape in the middle panel indicates the lack of recruitment and alveolar overdistension. Modified from [27]. P_L, airway pressure.