Is cough a feature of pulmonary edema or pleural effusion?

Cough as a Feature of Pulmonary Edema and Pleural Effusion

Both pulmonary edema and pleural effusion commonly cause cough, though the characteristics differ: pulmonary edema typically presents with dyspnea and dry cough that progresses to productive cough with pink frothy sputum, while pleural effusion causes predominantly dry cough with pleuritic chest pain. 1, 2, 3

Pulmonary Edema and Cough

Cough is a cardinal presenting symptom of pulmonary edema:

• Pulmonary edema initially presents with crackles, wheezing, and dry cough, then progresses to tachypnea, dyspnea, orthopnea, pink frothy sputum, and cyanosis 3
• The cough in pulmonary edema can be the sole presenting manifestation of congestive heart failure 4
• Patients with heart failure experience worsening cough when lying down due to fluid redistribution that increases pulmonary congestion 4
• The mechanism involves alveolar space and interstitial edema, with hyaline membrane formation in permeability edema 1

Clinical Context

• Dyspnea and frothy sputum (sometimes) accompany the cough in pulmonary edema 1
• Radiologic features include hazy opacities, Kerley lines, and batwing appearance in hydrostatic edema; patchy widespread parenchymal opacities in permeability edema 1
• Pleural effusion occurs more frequently with hydrostatic (cardiac) edema than permeability edema 1

Pleural Effusion and Cough

Cough is one of the most common presenting symptoms of pleural effusion:

• Patients most commonly present with dyspnea (initially on exertion), predominantly dry cough, and pleuritic chest pain 2
• In children with parapneumonic effusion/empyema, cough is a classic presenting symptom alongside dyspnea, fever, and malaise 1
• The cough associated with pleural effusion is typically nonproductive 2, 5

Mechanism and Associated Features

• Pleural effusion causes cough through mechanical irritation and compression of airways 1
• When thoracentesis removes large volumes rapidly, patients may develop severe cough, chest pain, or dyspnea, which are warning signs to stop fluid removal 1
• Rheumatoid arthritis, SLE, and other connective tissue diseases cause pleural effusion that manifests with cough 1

Pulmonary Embolism Connection

• Approximately 50% of patients with documented pulmonary embolism develop cough, which can occasionally be the presenting complaint 6
• Small distal emboli create alveolar hemorrhage resulting in hemoptysis, pleuritis, and pleural effusion 6
• Pulmonary embolism with pleural effusion typically presents with pleuritic chest pain (in ~75% of cases), and dyspnea is frequently out of proportion to the size of the effusion 7
• The effusion from pulmonary embolism usually occupies less than one-third of the hemithorax 7

Key Diagnostic Distinctions

When evaluating cough with suspected cardiopulmonary pathology:

• Pulmonary edema: Look for orthopnea, progression from dry to productive cough with pink frothy sputum, bilateral crackles, and signs of volume overload 3, 4
• Pleural effusion: Look for unilateral decreased chest expansion, dullness to percussion, reduced breath sounds, pleuritic chest pain, and patient lying on affected side 1, 2
• Ultrasound must be used to confirm pleural fluid presence and should guide thoracentesis 1

Critical Pitfalls

• Do not assume cough in cardiac patients is always medication-related (ACE inhibitors); worsening heart failure with pulmonary edema is more common and potentially serious 4
• In peritoneal dialysis patients, increased intraperitoneal pressures can cause GERD-related cough that mimics cardiac causes 1
• When removing pleural fluid, limit to 1-1.5 L at one sitting unless monitoring pleural pressure; severe cough during thoracentesis indicates precipitous pressure drop and risk of re-expansion pulmonary edema 1
• Dyspnea out of proportion to effusion size should prompt evaluation for pulmonary embolism 7