Fig. 1
From: Is mechanical power an under-recognised entity within the preterm lung?
Behaviour of change in delivered pressure (ΔP; A), ventilator rate (bpm; inflations per min B), tidal volume (VT; C), dynamic compliance (Cdyn; D), laminar (RLAM; E) and turbulent flow resistance (RTURB; F) during 90 min of standardised mechanical ventilation from birth (0 min) in 17 preterm lambs. The lung first underwent the transition (grey shading) from fluid-filled to aerated state during the first 3 min from birth; a period of falling lung resistance and increasing VT. Thereafter MV supported the aerated and surfactant-deficient preterm lung. Exogenous surfactant administered at 10 min (dotted vertical line) with resultant anticipated improvement in Cdyn and ventilator needs. C (VT) horizontal dash lines represent study protocol VT target range. All data mean and SD, except ventilator rate (mean and range), and expressed against body weight where appropriate. Waveforms were excluded from analysis if artefact present (such as circuit fluid). VT and Cdyn (both p < 0.0001) increased with time, whilst ventilator rate (p = 0.0015), ΔP (p < 0.0001) and RTURB decreased (p = 0.004) and RLAM (p = 0.32) was unchanged overall (all repeated measures two-way ANOVA)