Pulmonary Embolism

Pulmonary embolism (PE) is a medical condition characterised by the blockage of an artery in the lungs by a substance, often a blood clot, that has travelled from another part of the body.

The primary symptoms of PE include shortness of breath, chest pain upon breathing, and coughing up blood. Diagnosing and managing this condition effectively is very important for patient survival and quality of life.

Signs and Symptoms

The symptoms of PE are often sudden and may include dyspnea (shortness of breath), tachypnea (rapid breathing), pleuritic chest pain, cough, and hemoptysis (coughing up blood). Severe cases can present with cyanosis (blue discolouration of lips and fingers), collapse, and circulatory instability due to decreased blood flow through the lungs. Physical examination might reveal normal lung sounds, but in some cases, a pleural friction rub or pleural effusion may be detected. Severe right ventricular strain may be observed through signs like left parasternal heave and raised jugular venous pressure.

Risk Factors

About 90% of PEs are due to a deep vein thrombosis (DVT) originating above the knee. Risk factors include immobility, cancer, pregnancy, obesity, smoking, certain genetic conditions, and surgeries, particularly orthopaedic ones. Other factors like varicose veins, diabetes, and traumatic hip fractures also contribute to the likelihood of developing a PE.

Diagnosis

The diagnosis of PE relies on clinical criteria and selective testing. For low-risk patients, a normal D-dimer test can rule out PE. High-risk individuals require imaging like CT pulmonary angiography (CTPA), which is the preferred diagnostic tool. Other methods include lung ventilation/perfusion scans and proximal lower limb compression ultrasound.

Wells Score

The Wells score is commonly used to predict the probability of PE. It includes criteria such as clinical signs of DVT, alternative diagnosis less likely than PE, tachycardia, immobilisation, history of DVT or PE, hemoptysis, and malignancy. The score helps determine the need for further testing.

Treatment

Treatment primarily involves anticoagulant therapy. Initial treatments may include injectable anticoagulants like heparin, followed by oral vitamin K antagonists such as warfarin. In recent years, direct-acting oral anticoagulants (DOACs) have gained preference due to their ease of use and fewer monitoring requirements. For severe cases, thrombolysis or surgical interventions like pulmonary thrombectomy may be necessary.

Anticoagulation

Anticoagulants such as heparin, warfarin, and newer DOACs are used for at least three months. In cases where anticoagulation is contraindicated, an inferior vena cava filter may be used to prevent new clots from reaching the lungs.

Thrombolysis

For massive PE causing hemodynamic instability, thrombolysis is the treatment of choice. Catheter-directed thrombolysis is a newer technique offering concentrated delivery of clot-dissolving medication.

Surgery

Surgical intervention is rare but may be required for chronic pulmonary embolism leading to pulmonary hypertension, treated through pulmonary thromboendarterectomy.

Prognosis and Epidemiology

The prognosis of PE depends on the extent of lung involvement and the presence of other medical conditions. Untreated PE has a high mortality rate, but advancements in medical care have reduced this significantly. In the UK and other regions, PE contributes to a notable number of hospital admissions and fatalities each year.

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Self-assessment MCQs (single best answer)

Which of the following is a primary symptom of pulmonary embolism (PE)?

What imaging technique is preferred for diagnosing pulmonary embolism?

What is the Wells score used for?

Which of the following is a major risk factor for pulmonary embolism?

What is the first-line treatment for pulmonary embolism?

Which anticoagulant is often used initially in the treatment of PE?

In severe cases of pulmonary embolism causing hemodynamic instability, what treatment is preferred?

What might a physical examination reveal in a patient with a severe pulmonary embolism?

What alternative intervention may be used if anticoagulation is contraindicated?

Which symptom is NOT commonly associated with pulmonary embolism?