Pulmonary edema refers to fluid accumulation in the interstitial space spreading to the alveoli. This fluid accumulation can compromise oxygenating and ventilation.

Patients with underlying medical conditions that impair clearance and mobilization of body fluids are at high risk for developing pulmonary edema. This is common in patients with congestive heart failure (systolic or diastolic), cirrhosis, end-stage renal disease, and acute respiratory distress syndrome. Pulmonary edema can also develop as a medication side effect or in the setting of acute injury due to viral infections, negative intrathoracic pressure (following thoracentesis), pulmonary embolism, smoke inhalation, opioid overdose, or high-altitude lung injury.

Pulmonary edema primarily causes dyspnea either at rest, on exertion, or exacerbated with lying flat. Patients may also complain of cough productive of frothy sputum, diaphoresis, or increased work of breathing. Hypoxemia is common.