Pulmonary edema occurs when movement of liquid from the blood to the interstitial space and/or into the alveoli exceeds the return of liquid to the blood and its drainage through the lymphatics.

Causes of Pulmonary Edema

Imbalance of Starling Forces

• Increased pulmonary capillary pressure
• Hypoalbuminemia increased
• Negative interstitial pressure

The two most common forms of pulmonary edema are that initiated by an imbalance of Starling forces and that initiated by disruption of one or more components of the alveolar-capillary membrane.   

Altered Alveolar-Capillary Membrane Permeability (ARDS)

Primary alveolar-capillary membrane damage (Acute Respiratory Distress Syndrome)

Lymphatic Insufficiency

• Post lung transplant
• Lymphangitis carcinomatosis
• Fibrosing lymphangitis

Unknown or Incompletely Understood

• High-altitude pulmonary edema
• Neurogenic pulmonary edema
• Narcotic overdose pulmonary edema
• Pulmonary embolism
• Eclampsia
• Post cardioversion
• Post anesthesia
• Post cardiopulmonary bypass