Pulmonary Thromboembolism Initial Assessment

Clinical Presentation

Typical Signs and Symptoms  

The suspicion of pulmonary embolism is usually raised by the clinical symptoms. Dyspnea, pleuritic chest pain, and tachypnea (respiratory rate ≥20 breaths/minute) occur in most cases of pulmonary embolism. Dyspnea is the most frequent symptom, while tachypnea is its most frequent sign.            

Other signs and symptoms that may be present include tachycardia (heart rate [HR] >100 beats/minute [bpm]), cough, hemoptysis, syncope, non-pleuritic chest pain, wheezing, and hypotension. Clinical instability or cardiac arrest is indicative of a massive pulmonary embolism.  

Pleuritic Chest Pain  

Pleuritic chest pain with or without dyspnea is one of the most frequent presentations of pulmonary embolism. It may suggest a small embolism located distally near the pleura.  

Isolated Dyspnea  

Isolated dyspnea may occur suddenly or progressively (over several weeks). It is usually due to a more central pulmonary embolism (not affecting the pleura). It may be associated with a substernal angina-like chest pain that probably represents right ventricular ischemia.  

Worsening dyspnea may be the only symptom that indicates pulmonary embolism in patients with preexisting heart failure (HF) or pulmonary disease.  

Syncope or Shock  

Syncope or shock are the hallmark signs of central pulmonary embolism and usually result in severe hemodynamic repercussions. The signs of hemodynamic compromise and reduced heart flow are also usually present (eg systemic arterial hypotension, oliguria, cold extremities, and/or clinical signs of acute right heart failure).  

Physical Examination

Signs and Symptoms of Pulmonary Embolism  

Dyspnea is usually the primary symptom and systemic arterial hypotension that requires pressor support is the predominant sign. Syncope and/or cyanosis may be present in some patients.  

Signs and Symptoms of Massive Pulmonary Embolism  

One should raise suspicion of a massive pulmonary embolism if the patient presents with hemodynamic instability (systolic blood pressure of <90 mmHg, or a drop of ≥ 40 mmHg for >15 minutes, requiring vasopressors, or with clear evidence of shock), syncope, severe hypoxemia, or respiratory distress.

Diagnosis or Diagnostic Criteria

Clinical Pretest Probability of Pulmonary Embolism (CPTP)  

Evaluating the likelihood of pulmonary embolism in an individual patient according to the clinical presentation is of utmost importance in the interpretation of diagnostic test results and in the selection of an appropriate diagnostic strategy.  

A reasonable clinical suspicion is required to avoid missing the diagnosis of pulmonary embolism. A clinical evaluation allows the patients to be classified into probability categories corresponding to an increasing prevalence of pulmonary embolism. The clinical probability may be implicitly estimated by clinical judgment or explicitly by a validated prediction rule. All patients with possible pulmonary embolism should have their clinical probability assessed and documented. Patients should also be evaluated for risk factors for venous thromboembolism (VTE).  

Prediction Rule versus Clinical Judgment  

To identify a patient with a high likelihood of PE, prediction rules appear to be more accurate than clinical judgment. Clinical judgment can discern if the patient has a low likelihood of pulmonary embolism. Patients who have a low clinical probability of pulmonary embolism, no lower limb deep vein thrombosis (DVT), and non-diagnostic lung scan have a low risk of pulmonary embolism.  

Estimation of Pretest Probability of Pulmonary Embolism  

Example methods: Wells, Wicki, Kline, revised Geneva score  

Wells method is the most frequently used clinical prediction rule. In any of the methods used, the proportion of patients with pulmonary embolism is around 10% in the category of low probability, 30% in moderate probability, and 65% in high probability. Clinical evaluation allows patients to be classified into probability categories corresponding to an increasing prevalence of pulmonary embolism.    

Wells (Canada) Method  

Wells method requires that the patient have clinical features suggestive of pulmonary embolism (eg breathlessness, and/or tachypnea with or without pleuritic chest pain, and/or hemoptysis). Along with two other features, there should be the absence of another reasonable clinical explanation or the presence of a major risk factor. If both are true, then the probability is high; if only one of the above is true then the probability is intermediate; and if neither is true then the probability is low. 

Pulmonary Embolism Rule-Out Criteria (PERC)  

PERC helps exclude patients at very low risk for pulmonary embolism. Studies show that PERC validation done prior to D-dimer testing is 100% sensitive. The presence of any of the following indicates a positive PERC: Age > 49 years old; pulse rate >99 beats/minute; pulse oximetry <95% at room air; hemoptysis; previously intubated due to surgery or trauma or hospitalization within the last 4 weeks; patient on exogenous Estrogen therapy; a clinical history of venous thromboembolism; and unilateral leg (calf) swelling.

Prognostic Risk Assessment  

The prognostic risk assessment is done using Pulmonary Embolism Severity Index (PESI) and simplified PESI (sPESI), Hestia criteria, cardiac markers (eg cardiac troponin I, natriuretic peptide), and imaging tests and classifies patients as follows:

• High risk: Hemodynamic instability (eg shock, persistent arterial hypotension), PESI class III-V or sPESI ≥1, presence of signs of right ventricular dysfunction upon imaging tests, and the presence of cardiac markers
• Intermediate risk: PESI class III-V or sPESI ≥1, presence of signs of right ventricular dysfunction upon imaging tests, and/ or presence of cardiac markers
  • In intermediate-high risk patients, both cardiac markers and imaging results are positive for abnormalities
  • Either cardiac markers or signs of right ventricular dysfunction are present in patients with intermediate-low risk
• Low risk: No signs of right ventricular dysfunction on imaging tests (eg echocardiography, CT angiogram) and negative cardiac markers