PULMONARY EMBOLISM (PE)

Definition:

Pulmonary embolism is the acute blockage of one or more pulmonary arteries by an embolus, most commonly a blood clot (thrombus) that originates from deep vein thrombosis (DVT), usually in the lower limbs. It can impair respiratory and circulatory function and is a medical emergency.

Epidemiology:

• Incidence: about 1–2 cases per 1,000 people per year.

• Higher risk in hospitalized patients, the elderly, cancer patients, and postoperative cases.

• Third most common cause of cardiovascular death (after myocardial infarction and stroke).

• Often underdiagnosed: may present with no symptoms or sudden collapse.

Pathophysiology (Mechanism):

• A venous thrombus, usually from the legs or pelvis, detaches, becomes an embolus, and travels through the venous circulation to the right side of the heart, then into the pulmonary artery.

• The blockage causes a ventilation/perfusion mismatch, resulting in hypoxemia, increased pulmonary vascular resistance, and acute strain on the right ventricle.

• In severe cases: hemodynamic collapse and sudden death.

Causes and Risk Factors:

Main causes:

• Deep vein thrombosis (DVT)

• Less common: fat emboli, tumor emboli, amniotic fluid embolism, air embolism

Risk factors:

• Prolonged immobility (e.g., long travel, bed rest)

• Recent surgery (especially orthopedic, abdominal, or pelvic)

• Trauma or fractures

• Cancer

• Hormone therapy / oral contraceptives

• Pregnancy and postpartum

• Previous PE or DVT

• Obesity

• Smoking

• Older age

• Inherited thrombophilia

Diagnosis (Explained):

1. History and symptoms:

• Sudden shortness of breath

• Pleuritic chest pain

• Tachycardia

• Cough, sometimes with hemoptysis

• Syncope in severe cases

• Signs of DVT (leg swelling, redness, pain)

2. Physical examination: often nonspecific (tachypnea, cyanosis, hypotension)

3. Diagnostic tests:

• ECG: may show tachycardia or S1Q3T3 pattern

• Chest X-ray: often normal

• CT pulmonary angiography (CTPA): gold standard; directly visualizes embolus

• Echocardiogram: useful in severe cases to assess right heart strain

• Lower limb Doppler ultrasound: to detect DVT

• D-dimer: elevated in thrombosis (useful in low-risk patients)

• Ventilation/perfusion (V/Q) scan: alternative when CT is contraindicated

• Arterial blood gas (ABG): shows hypoxemia, hypocapnia

Therapy (Explained):

1. Anticoagulant therapy (essential):

• Low molecular weight heparin (LMWH) or fondaparinux initially

• Long-term oral anticoagulants:

• Vitamin K antagonists (e.g., warfarin)

• Direct oral anticoagulants (DOACs): apixaban, rivaroxaban, dabigatran

2. Thrombolytic therapy (for severe/high-risk PE):

• Fibrinolytics (e.g., alteplase) dissolve clots

• Indicated in hemodynamically unstable patients (shock or persistent hypotension)

3. Surgical or catheter-directed embolectomy:

• For patients with massive PE who cannot receive thrombolytics

4. Oxygen therapy and ventilatory support

• In cases of severe hypoxemia

5. Inferior vena cava (IVC) filter:

• For patients who cannot receive anticoagulants

Nursing Care:

• Monitor vital signs frequently

• Check oxygen saturation (SpO₂) and respiratory status

• Administer anticoagulants properly, monitor for signs of bleeding

• Observe for complications: bleeding gums, hematuria, melena, bruises

• Patient education:

• Importance of adherence to anticoagulant therapy

• Recognize signs of recurrence

• Encourage early mobilization, if safe

• Ensure proper hydration to reduce clot risk

• Provide emotional support, as patients may be anxious or fearful

Advice and Prevention:

• Early mobilization after surgery or during hospital stay

• Graduated compression stockings for high-risk patients

• Pharmacologic prophylaxis in at-risk patients (e.g., LMWH or DOACs)

• Avoid prolonged immobility, especially during travel

• Smoking cessation

• Weight management

• Prompt treatment of DVT

• Education on risk factors and symptoms, especially for pregnant women or those on hormone therapy