1. The Mead and Whittenberger graphs (a–c) obtained by plotting the airway opening flow versus the resistive pressure drop (Pfr) during a single breath.
The Mead and Whittenberger graphs (a–c) obtained by plotting the airway opening flow versus the resistive pressure drop (Pfr) during a single breath. Data from a, d) a healthy subject, b, e) a chronic obstructive pulmonary disease (COPD) patient not flow limited and c, f) a flow-limited COPD patient. The regression lines in the left and in the middle graph represent airway resistance at breathing frequency. In the right graph expiratory flow limitation is demonstrated by the presence of a region in which airway opening flow is decreasing while Pfr is increasing. Traces obtained during forced oscillation technique application (d–f) show the corresponding time courses of Pfr (continuous line) and respiratory system reactance (Xrs; dashed line). The arrows indicate end inspiration, i.e. time before this point is inspiration, afterwards is expiration. Insp: inspiration. Reproduced from [60] with permission from the publisher.
N.G. Koulouris, and G. Hardavella Eur Respir Rev 2011;20:
©2011 by European Respiratory Society