Fig. 2. Pressure volume curves. (A) shows the difference between term (n=9) and preterm controls (n=13, p<0.001). (B) shows deflation curves for the four different surfactant preparations. Synsurf-2 (n=7, p=0.0068), Synsurf-3 (n=6, p=0.0031), and Surfacten® (n=18, p<0.001) showed higher pressure volume curves in the term group than the preterm group; Synsurf-1 (n=6, p=0.4811) showed no difference. Mann Whitney U test was used to compare volumes at 15 cm H₂O pressure.