A 59-year-old woman with a 10-year history of type 2 diabetes mellitus is noted by her physician to have bilateral pitting edema of the ankles and feet. No erythema is noted. On questioning, the patient also repos shoness of breath on exeion and states that she has been using 3 pillows at night in order to sleep comfoably. A chest x-ray film demonstrates pulmonary venous congestion and interstitial edema indicative of pulmonary edema. Which of the following physiologic mechanisms is most likely the immediate cause of the pulmonary edema?

The cause of pulmonary edema in congestive hea failure is an increase in the hydrostatic pressure at the level of the capillaries of the lung. This increased pressure serves to drive fluid out of the capillaries and into the alveoli. The other reasons cited in the choices can also cause pulmonary edema, but occur in other clinical settings. Damage to endothelial cells can occur in vasculitis. Damage to the epithelial lining of the alveoli can occur in pneumonia and respiratory distress syndrome. Low serum albumin can be seen in liver and kidney disease.