What are the clinical features of Pulmonary Embolism (PE)?

Clinical Features of Pulmonary Embolism

The most common clinical features of PE, in descending order of frequency (70% to 10%), are dyspnoea, tachypnoea, pleuritic chest pain, apprehension, tachycardia, cough, haemoptysis, leg pain, and clinical signs of DVT. 1

Most Frequent Presenting Symptoms

Dyspnoea is the single most common symptom, occurring in approximately 80% of patients with PE. 1, 2, 3 This can manifest as:

• Acute and severe dyspnoea in central PE 1, 2
• Mild and potentially transient dyspnoea in small peripheral PE 1, 2
• Isolated worsening of dyspnoea in patients with pre-existing heart failure or pulmonary disease 1, 2

Tachypnoea (respiratory rate >20/min) is present in approximately 70% of patients. 4

Chest pain occurs in 38-56% of patients and presents in two distinct patterns: 1, 4, 3

• Pleuritic chest pain (sharp, stabbing, worsens with breathing) in approximately 52% of cases, caused by pleural irritation from distal emboli 1, 4
• Substernal angina-like chest pain in approximately 12% of cases, reflecting right ventricular ischaemia from acute RV strain 1, 4

Critical Diagnostic Triad

The combination of dyspnoea, tachypnoea, or pleuritic pain is present in 97% of PE patients—only 3% lack all three features. 1, 4 This means:

• The absence of dyspnoea, tachypnoea (>20/min), AND pleuritic pain virtually excludes PE. 1
• Dyspnoea plus tachypnoea is absent in only 10% of patients 1

Less Common but Important Presentations

Syncope or pre-syncope occurs in 19-26% of patients and can occur regardless of hemodynamic stability. 1, 2, 3 This is an infrequent but important presentation that may indicate central PE. 1

Haemoptysis is relatively uncommon, occurring in only 5-7% of patients. 1, 3

Clinical signs of deep vein thrombosis (leg pain, unilateral leg swelling) are present in approximately 29% of patients. 1, 5 Isolated symptoms and signs of DVT without respiratory symptoms occur in only 3% of cases. 3

Three Main Clinical Presentations

PE typically presents in one of three distinct patterns: 1

1. Circulatory collapse with hypotension and/or loss of consciousness, with central chest tightness (massive PE) 1
2. Pleuritic chest pain with dyspnoea (peripheral PE causing pulmonary infarction) 1, 4
3. Isolated dyspnoea of rapid onset (central PE without infarction) 1

Physical Examination Findings

Common physical signs include: 5

• Tachypnoea in 39% 5
• Hypoxia in 35% 5
• Tachycardia in 33% 5
• Signs of DVT in 29% 5

Important caveat: Approximately 20% of PE patients have normal arterial oxygen pressure, so normal oxygenation does not exclude PE. 4

Critical Diagnostic Limitations

Individual symptoms and signs have poor diagnostic accuracy—no single feature has a predictive value exceeding 80%. 1 Features with high sensitivity have low specificity, and vice versa. 1

Approximately 48% of PE patients do not have chest pain of any type. 4 Therefore, absence of pain cannot be used to rule out PE. 4

Only 1% of patients are completely asymptomatic at presentation, with PE discovered incidentally. 1, 3

Transient Symptoms

Symptoms may be transient or have resolved by the time of evaluation, particularly with small peripheral emboli. 2 This occurs because:

• Small peripheral emboli may cause temporary symptoms that resolve as the body's natural thrombolytic system begins working 2
• Emboli may partially obstruct vessels temporarily before moving or dissolving 2

A high clinical suspicion for PE must be maintained even when symptoms are transient or have resolved at evaluation. 2 Transient symptoms can lead to delayed diagnosis or misdiagnosis. 2

Special Clinical Scenarios

Young patients (especially women on oral contraception) presenting with isolated pleuritic chest pain: PE is very unlikely if there are no risk factors for thromboembolism AND the patient is either (a) aged under 40 OR (b) has a respiratory rate <20/min plus a normal chest radiograph. 1

Post-operative patients: PE is often confused with segmental/lobar collapse or infection in the period immediately after upper abdominal surgery. 1

Differential Diagnosis Considerations

Conditions that may present with similar features to PE include: 1

• Myocardial infarction
• Left heart failure
• Pericarditis
• Dissecting aneurysm
• Pneumothorax
• Pneumonia
• Lobar collapse

Standard investigations (ECG, chest radiography, lung function tests) are valuable primarily for eliminating these alternative cardiac and respiratory diagnoses. 1