Can pulmonary embolism (PE) cause wheezing in a patient with a history of asthma or COPD?

Can Pulmonary Embolism Cause Wheezing?

Yes, pulmonary embolism can definitely cause wheezing, though it is an uncommon presentation that can mimic asthma or COPD and lead to diagnostic confusion. 1, 2

Mechanism and Clinical Presentation

Pulmonary embolism causes wheezing through reflex bronchoconstriction triggered by the embolic event. 1 This can present so prominently that it mimics bronchial asthma, making PE an important differential diagnosis when evaluating any patient with new-onset wheezing or wheezing that doesn't respond appropriately to standard bronchodilator therapy. 1, 2

The key clinical scenario is a patient presenting with sudden onset wheezing and respiratory distress that fails to improve adequately with standard asthma therapy (beta-agonists, steroids, theophylline). 2 In one documented case, a 75-year-old woman developed acute wheezing on awakening that was initially treated as asthma, but her respiratory failure persisted despite appropriate bronchodilator therapy, ultimately revealing bilateral pulmonary emboli. 2

Diagnostic Approach in Patients with Asthma or COPD History

Initial Assessment

• Assess for sudden onset of symptoms, particularly if the wheezing pattern differs from the patient's typical asthma or COPD exacerbations 3
• Look for associated features suggesting PE: pleuritic chest pain, hemoptysis, unilateral leg swelling, or risk factors for venous thromboembolism 3
• Document vital signs including oxygen saturation; PE patients may have more profound hypoxemia than expected for the degree of wheezing 3

Critical Diagnostic Pitfall

The most dangerous error is assuming all wheezing in a patient with known asthma or COPD represents an exacerbation of their underlying disease. 4, 3 The American Thoracic Society specifically notes that acute exacerbations of respiratory symptoms in COPD patients may be caused by extrapulmonary mechanisms including pulmonary embolism. 4

When to Suspect PE Despite Wheezing

• Wheezing with sudden onset rather than gradual worsening 1, 2
• Inadequate response to appropriate bronchodilator therapy 2
• Wheezing accompanied by orthopnea may suggest cardiac causes including PE-related right heart strain 5
• Presence of risk factors: recent immobilization, surgery, malignancy, or hypercoagulable state 6

Imaging Performance in Asthma Patients

Good news: A history of asthma does NOT impair the diagnostic accuracy of PE imaging studies. 7 A large study of 19,412 adults found that:

• Nondiagnostic results were comparable between asthma and non-asthma patients for both VQ scanning (3.3% vs 3.8%) and CT pulmonary angiography (1.6% vs 1.5%) 7
• False-negative rates were not higher in asthma patients for either modality 7
• Therefore, do not hesitate to order PE imaging in patients with asthma who present with atypical or refractory wheezing 7

Special Consideration: Asthma as a PE Risk Factor

Severe asthma itself may be a risk factor for pulmonary embolism due to chronic inflammation activating coagulation pathways. 6 The pathophysiology involves:

• Increased tissue factor expression 6
• Decreased protein C anticoagulant activity 6
• Overproduction of plasminogen activator inhibitor type 1 (PAI-1) 6

Patients with severe asthma and frequent exacerbations warrant higher clinical suspicion for PE when presenting with respiratory symptoms. 6

Practical Algorithm

1. Any patient with wheezing should have spirometry to document reversibility 4
2. If wheezing is sudden onset, consider PE in the differential 1, 2
3. If standard asthma/COPD therapy fails to improve symptoms adequately, obtain contrast-enhanced chest CT or VQ scan 2
4. In patients with known asthma/COPD, maintain high suspicion for PE when symptoms are atypical or refractory 4, 3
5. Do not let a history of asthma dissuade you from ordering PE imaging—diagnostic performance is equivalent 7

Additional Differential Considerations

When evaluating wheezing, remember that multiple cardiac conditions can also present with wheezing ("cardiac asthma") due to pulmonary venous hypertension causing reflex bronchoconstriction. 4, 5 Heart failure should be considered alongside PE, particularly in patients with orthopnea and wheezing. 5 BNP/NT-proBNP measurement helps distinguish cardiac from pulmonary causes. 5