Pulmonary Edema, Acute

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Acute onset of profound dyspnea and orthopnea

• Jugular venous distention, diffuse pulmonary rales, and tachycardia

• Left ventricular (LV) systolic or diastolic dysfunction

GENERAL CONSIDERATIONS

• Clinical syndrome characterized by sudden development of respiratory distress and interstitial pulmonary edema

• Primary pathogenic mechanism is an elevation in pulmonary capillary pressure due to LV systolic or diastolic dysfunction

• Compensatory mechanisms result in neurohumoral activation, tachycardia, and elevated systemic vascular resistance that further increase LV filling pressures and worsen pulmonary edema

• Can occur in the absence of heart disease with fluid overload due to blood transfusion or severe renal disease

• Results in reduced diffusion capacity and lung compliance, hypoxia, and dyspnea

• Rate of increase in pulmonary edema related to pulmonary venous pressure and capacity of the lymphatic vessels to remove excess fluid

• Causes of acute pulmonary edema:

  • – Myocardial ischemia

  • – Acute aortic insufficiency

  • – Acute mitral regurgitation

  • – Mitral stenosis

  • – Renal vascular hypertension

  • – Other conditions in the presence of preexisting diastolic dysfunction (eg, fever, sepsis, anemia, thyroid disease, cardiac dysrhythmia)

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Acute onset or worsening of cough and dyspnea

• Chest discomfort

• Diaphoresis

PHYSICAL EXAM FINDINGS

• Tachypnea and use of accessory respiratory muscles

• Tachycardia

• Jugular venous pressure may be elevated

• Diffuse pulmonary rales

• Hypertension or hypotension

• New or changed murmur

• S₃ or S₄

• Peripheral edema may be present

DIFFERENTIAL DIAGNOSIS

• Pulmonary emboli

• Bilateral pneumonia

• Acute respiratory distress syndrome

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• Arterial blood gases: can quantify the level of hypoxia

• CBC: may suggest infection or identify anemia as precipitating events

• Electrolyte, blood urea nitrogen, and creatinine: may identify renal dysfunction

• Cardiac enzymes (eg, troponin): may be elevated in the presence of myocardial ischemia

• Thyroid function tests

ELECTROCARDIOGRAPHY

• Sinus tachycardia

• Left atrial enlargement

• Atrial fibrillation or flutter with a rapid ventricular response

• ST- and T-wave changes suggestive of myocardial ischemia

• LV hypertrophy

IMAGING STUDIES

• Chest x-ray:

  • – Variable pulmonary vascular redistribution and interstitial edema

  • – Perihilar alveolar edema (“butterfly” appearance)

  • – Cardiac silhouette may be normal or enlarged

  • – Pleural effusions may or may not be present

• Transthoracic echocardiography:

  • – To assess the degree of LV systolic and/or diastolic dysfunction

  • – To identify the presence of valvular disease

  • – To estimate the pulmonary artery systolic pressure and right atrial pressure

  • – New wall motion abnormalities may suggest myocardial ischemia or injury

DIAGNOSTIC PROCEDURES

• Right heart catheterization: often not necessary but typically reveals the following:

  • – Marked elevations in pulmonary capillary wedge pressure

  • – Pulmonary artery ...