Relationship between static transpulmonary pressure (in cm H2O) and lung volume, expressed as percentage of predicted total lung capacity (TLC). A monoexponential curve has been fitted to the pressure-volume data in each instance (see text and Table 2 for details). Four main patterns were noted.(A) Normal TLC, static compliance (Cst) and shape constant K (Patient 11). (B) Normal TLC, but reduced Cst and K (Patient 16). (C) Reduced TLC, Cst and K (Patient 15). (D) Normal TLC, but elevated Cst and K (Patient 12).