Fig. 4

The effect of CPAP on the intra-breath oscillometry values. The effects of different CPAP levels on oscillometry variables are depicted as (a) box-plot diagrams (ReE, ReI, ΔR, XeE, XeI, ΔX) and (b) individual changes and box-plot diagrams (AXV, AXV’). With increasing CPAP levels stepwise change was visible on the Xrs during expiration indicating decreasing tEFL during tidal breathing. The CPAP level required to diminish expiratory Xrs was highly variable between patients. P values are established by the Friedman ANOVA test; the r values are established by Kendall’s concordance test. (n = 33)

ReE = end-expiratory resistance; ReI end-inspiratory resistance; ΔR = difference between ReE and ReI; XeE = end-expiratory reactance; XeI end-inspiratory reactance; ΔX = difference between XeE and XeI; AXV = area of the Xrs vs. volume loop; AXV’= area of Xrs vs. flow loop; CPAP = continuous positive airway pressure;