Absence of clinical pulmonary edema despite elevated wedge pressures.

Pulmonary hemodynamic data were collected for 116 patients with a resting mean pulmonary artery wedge pressure of 25 mm Hg or greater who underwent exercise during cardiac catheterization without showing acute pulmonary edema. While the mechanism for the absence of evidence of pulmonary edema with pulmonary artery wedge pressure in excess of plasma oncotic pressure is unclear, presumably, it relates to compensatory changes in the structure and function of the pulmonary capillaries, alveolar wall, and lymphatic drainage capacity.