Pulmonary edema

Pulmonary edema is the accumulation of fluid in the lung interstitium and air spaces. Cardiogenic edema results from raised pulmonary venous pressure, usually left ventricular failure or mitral valve disease. Non-cardiogenic causes include ARDS, fluid overload, renal failure and neurogenic edema.

Clinical presentation

Breathlessness, orthopnoea and paroxysmal nocturnal dyspnoea, with bibasal crackles, raised jugular venous pressure and peripheral edema in heart failure. Acute edema can present with frothy sputum and severe hypoxia.

Radiographic features

Chest radiograph

Signs appear roughly in order of rising pulmonary venous pressure:

• Upper lobe venous diversion: upper zone vessels as large as or larger than lower zone vessels
• Interstitial edema: Kerley B lines (short horizontal lines at the lung bases), peribronchial cuffing, thickened fissures
• Alveolar edema: bilateral perihilar air-space shadowing, classically in a bat-wing distribution
• Pleural effusions, often bilateral
• Cardiomegaly in chronic heart failure (see cardiothoracic ratio)

Ultrasound

Multiple bilateral B-lines on lung ultrasound are a sensitive bedside sign of interstitial fluid.

Treatment and prognosis

Sit the patient up, give oxygen, treat with diuretics and vasodilators, and consider non-invasive ventilation. Find and treat the cause — for example acute coronary syndrome, arrhythmia or valve disease.

Differential diagnosis

• Bilateral pneumonia (including atypical and viral infection)
• ARDS (usually without cardiomegaly, effusions or septal lines)
• Pulmonary hemorrhage