Secondary Pulmonary Edema

Abstract

Secondary pulmonary edema may result from mitral stenosis, mitral regurgitation, or left heart failure. Each of these pathologic conditions elevate left atrial pressure and thereby increase pulmonary microvascular pressure. However, the degree to which left atrial pressure is elevated will determine if intraalveolar edema will occur. The rate at which fluid will traverse the pulmonary microvascular membrane is dependent upon the balance of intravascular and extravascular hydrostatic pressures, the intravascular to extravascular oncotic pressure gradient, hydraulic conductivity of the pulmonary microvascular membrane, and the permeability of the pulmonary microvascular membrane to plasma proteins. The relationship of these pressures and characteristics of the pulmonary microvascular membrane can be described by the Starling Equation: