What are the clinical signs and symptoms of pulmonary embolism?

Clinical Signs and Symptoms of Pulmonary Embolism

The clinical presentation of pulmonary embolism is highly non-specific, but at least one of four cardinal symptoms—sudden-onset dyspnea (most common at 80%), pleuritic chest pain (52%), syncope (19-26%), or hemoptysis (7-11%)—is present in 94% of cases, and these symptoms should prompt immediate consideration of PE when unexplained by other causes. 1, 2, 3

Cardinal Symptoms (In Order of Frequency)

Dyspnea (Shortness of Breath)

• Dyspnea is the most common presenting symptom, occurring in approximately 80% of PE patients 2, 3
• The character varies dramatically by embolus location: acute and severe in central PE versus mild and potentially transient in small peripheral PE 1, 4, 2
• In patients with pre-existing heart failure or pulmonary disease, worsening dyspnea may be the only symptom indicative of PE—this represents a critical diagnostic pitfall 1, 4, 2
• Progressive dyspnea over several weeks can occur, mimicking other causes of chronic dyspnea 1

Chest Pain (Two Distinct Patterns)

• Pleuritic chest pain occurs in 52% of cases, characterized as sharp, stabbing, or burning pain that intensifies with respiration, coughing, or deep breathing 1, 4, 2

  • Caused by pleural irritation from distal emboli leading to alveolar hemorrhage (often incorrectly termed "pulmonary infarction") 1, 4, 5
  • Typically indicates peripheral PE with pleural involvement 4, 2
  • May be accompanied by hemoptysis 1, 2

• Substernal angina-like chest pain occurs in 12% of cases, reflecting right ventricular ischemia from acute RV strain in central PE 4, 2

  • Requires differentiation from acute coronary syndrome or aortic dissection 1

Syncope or Pre-Syncope

• Occurs in 19-26% of cases and is associated with higher prevalence of hemodynamic instability and right ventricular dysfunction 1, 2
• May occur even without overt hemodynamic instability 4
• Recent evidence suggests acute PE may be present in 17% of patients presenting with syncope, even when an alternative explanation exists 1

Hemoptysis

• Present in 7-11% of cases, resulting from alveolar hemorrhage caused by small distal emboli 1, 2
• Typically associated with peripheral PE and pleural involvement 2

Physical Examination Findings

Vital Sign Abnormalities

• Tachypnea (respiratory rate >20/min) is present in 70% of cases 2
• Tachycardia (heart rate >100/min) occurs in 26-40% of cases 1, 2
• Hemodynamic instability (shock or persistent hypotension) is rare but indicates central or extensive PE with severely reduced haemodynamic reserve and defines high-risk PE 1, 2

Other Physical Signs

• Signs of deep vein thrombosis are present in only 15% of cases 2
• Cyanosis occurs in 11% of cases 2
• Fever (>38.5°C) is present in 7% of cases 2
• Pleural friction rub may be present with peripheral PE causing pleural irritation 5

Electrocardiographic Findings

• Right ventricular strain patterns are found in approximately 50% of cases, more commonly in severe PE 1, 2
• Specific patterns include:
  • S1Q3T3 pattern (S wave in lead I, Q wave and inverted T wave in lead III) 1, 2
  • T wave inversion in leads V1-V4 1, 2
  • QR pattern in V1 1, 2
  • Right bundle branch block (complete or incomplete) 1, 2
• Sinus tachycardia may be the only abnormality in milder cases, present in 40% of patients 1
• Atrial arrhythmias, most frequently atrial fibrillation, may be associated with acute PE 1

Laboratory and Imaging Findings

Arterial Blood Gas

• Hypoxemia is present in approximately 75% of cases 2
• Critical pitfall: Up to 20-40% of patients have normal arterial oxygen pressure (PaO₂) and normal alveolar-arterial oxygen gradient—normal oxygenation does NOT exclude PE 1, 2
• Hypocapnia is often present 1, 2

Chest X-Ray

• Frequently abnormal but findings are non-specific 1
• Common findings include:
  • Atelectasis or infiltrate (49%) 2
  • Pleural effusion (46%), frequently hemorrhagic 2
  • Elevated hemidiaphragm (36%) 2
  • Decreased pulmonary vascularity (36%) 2
  • Pleural-based opacity suggesting infarction (23%) 2
• Primary value is excluding other causes of dyspnea or chest pain, not diagnosing PE 1

Clinical Presentation Patterns by PE Location

Central PE

• Acute, severe dyspnea of rapid onset 4, 2
• Substernal chest pain with anginal characteristics 4, 2
• Higher probability of hemodynamic instability 2
• More frequent syncope 2
• More prominent hemodynamic consequences 4

Peripheral PE

• Mild, sometimes transient dyspnea 4, 2
• Pleuritic chest pain 4, 2
• Hemoptysis 2
• Mild pleural effusion 2

Critical Diagnostic Pitfalls to Avoid

• Do not rule out PE based on normal oxygen saturation—up to 40% of patients may have normal SaO₂ 1, 2
• Do not dismiss transient or mild symptoms—small peripheral PE can present with intermittent, mild dyspnea 4
• Individual symptoms lack specificity—no single clinical sign or symptom has predictive value exceeding 80% 4
• Nearly half (48%) of PE patients have no chest pain of any type—absence of pain does not exclude PE 4
• Only 3% of patients lack all four cardinal symptoms (dyspnea, chest pain, syncope, hemoptysis), but 1% may be completely asymptomatic 2, 3
• Isolated symptoms of deep vein thrombosis without pulmonary symptoms occur in only 3% of cases 3
• Many cases of fatal PE are unrecognized and undiagnosed at autopsy, suggesting that current clinical concepts may be too narrow and biased toward symptomatic cases 6

Risk Stratification Based on Presentation

• High-risk PE is defined by hemodynamic instability (persistent arterial hypotension with systolic BP <90 mmHg or shock) and indicates high risk of early mortality (>15%) 1, 2
• In the presence of shock or hypotension, it is not necessary to confirm RV dysfunction to classify as high-risk PE 1
• Non-high-risk PE requires additional evaluation with markers of RV dysfunction and myocardial injury to determine intermediate versus low risk 1

Predisposing Factors

• Knowledge of predisposing factors for VTE is essential in determining clinical probability, which increases with the number of factors present 1
• However, approximately 40% of patients with PE have no identifiable predisposing factors (unprovoked PE) 1, 2