– Life-threatening condition caused by the blockage of pulmonary arteries by a blood clot
– Blood clots typically originate from the deep veins of the legs known as deep vein thrombosis (DVT)
– Causes obstruction of blood flow to the lungs
– Severity varies from asymptomatic cases to fatal massive PE

– Blood clots in the deep veins of the legs (DVT) that dislodge and migrate to the lungs

– Immobilization, surgery, trauma, cancer, pregnancy, oral contraceptives, hormone replacement therapy, obesity, smoking, genetic predisposition (e.g., factor V Leiden mutation), conditions promoting blood clotting (e.g., antiphospholipid syndrome)

– Pelvic veins, upper extremity veins, right heart chambers

Major risk factors include:
– History of previous DVT or PE
– Prolonged immobility (e.g., bed rest, long-distance travel)
– Surgery (major abdominal, pelvic, or orthopedic like hip/knee replacements)
– Trauma (major injury)
– Cancer (active or history of cancer)
– Inherited blood clotting disorders (e.g., thrombophilia)
– Heart failure or chronic lung disease

Risk is increased by:
– Smoking
– Obesity
– Advanced age
– Hormonal therapy (e.g., oral contraceptives, hormone replacement therapy)
– IV drug use
– Lower-limb issues (e.g., fractures, varicose veins)

Obstetric factors include:
– Late pregnancy, postpartum period, and Caesarean section

Reduced mobility from hospitalization, institutional care, or long periods of immobility increases the risk of clot formation

Key factors include:
– Increased blood coagulability
– Reduced mobility
– Blood vessel abnormalities

Cancer (especially abdominal/pelvic malignancies or advanced/metastatic cancer) increases the risk of PE by promoting hypercoagulability

1. Obstruction and Reduced Blood Flow: A blood clot obstructs the pulmonary arteries, reducing blood flow to the lungs.
2. Ventilation-Perfusion Mismatch: Clot-induced obstruction creates a mismatch between ventilation and perfusion, impairing the exchange of oxygen and carbon dioxide.
3. Gas Exchange Impairment: Reduced blood flow leads to inadequate oxygen exchange and carbon dioxide elimination, causing hypoxia (low oxygen) and hypercapnia (high carbon dioxide).
4. Increased Pulmonary Artery Pressure: Obstruction increases pressure in the pulmonary arteries, straining the right side of the heart, which can lead to right heart failure and shock.

– A blood clot obstructs the pulmonary arteries, reducing blood flow to the lungs.

– Clot-induced obstruction creates a mismatch between ventilation and perfusion, impairing oxygen and carbon dioxide exchange.

– Inadequate oxygen exchange and carbon dioxide elimination
– Causes hypoxia (low oxygen) and hypercapnia (high carbon dioxide).

– Right heart strain
– Right heart failure
– Shock

– Obstruction by the clot reduces blood flow to the lungs, leading to ventilation-perfusion mismatch, impaired gas exchange, and increased pulmonary artery pressure which strains the right heart.

– Acute coronary syndrome
– Pneumonia
– Pleurisy
– Pneumothorax
– Anxiety or panic disorder
– Musculoskeletal chest pain
– Heart failure
– Aortic dissection
– Cardiac tamponade
– Sepsis

– 50-100 cases per 100,000 individuals annually

– 30,000–40,000/year

– Incidence increases with age

– Yes

• Sudden onset dyspnea
• Pleuritic chest pain
• Tachypnea
• Tachycardia
• Cough (sometimes with bloody sputum)
• Hemoptysis
• Syncope or near-syncope

Diagnosis based on:
– Symptoms: Acute breathlessness, pleuritic chest pain, hemoptysis, dizziness, syncope
– Signs: Tachypnea, tachycardia, cyanosis, hypoxia, elevated jugular venous pressure, heart rhythm abnormalities, pleural rub, systemic hypotension, cardiogenic shock

Wells Criteria: Assesses the risk of PE based on clinical features
– Score ≤4: PE unlikely; consider D-dimer
– Score >4: PE likely; consider imaging

Wells Criteria Components:
– Clinical signs of DVT: 3 points
– PE is the #1 diagnosis or equally likely: 3 points
– Heart rate >100 bpm: 1.5 points
– Immobilization ≥3 days or recent surgery: 1.5 points
– Previous PE or DVT: 1.5 points
– Hemoptysis: 1 point
– Malignancy with recent treatment: 1 point

PERC is used when there’s a low pre-test probability of PE (<15%):
– Negative PERC reduces the probability of PE to <2%
– Criteria (all must be absent):
– Age <50
– Heart rate <100
– Oxygen saturations ≥94%
– No previous DVT or PE
– No recent surgery/trauma in the past 4 weeks
– No hemoptysis
– No unilateral leg swelling
– No estrogen use

2-Level PE Wells Score:
– PE likely (>4 points): Immediate CTPA or anticoagulation
– PE unlikely (≤4 points): D-dimer test and further management based on results

Initial imaging: CTPA
V/Q scanning: Considered if:
– Normal chest x-ray
– No significant cardiopulmonary disease
– Renal impairment

• Medical History & Physical Examination
• Chest X-ray (CXR): Rule out other causes of symptoms
• Pulmonary Embolus Rule-out Criteria (PERC): Use to rule out PE when suspicion is low; all criteria must be absent for a negative result
• Two-level PE Wells’ Score: Calculate score to assess PE likelihood; >4 points suggests PE likely
• CT Pulmonary Angiogram (CTPA): Perform immediately if PE is likely (Wells’ >4)
• Interim Anticoagulation: Administer if CTPA is delayed or contraindicated
• Proximal Leg Vein Ultrasound: Consider if CTPA is negative but DVT is suspected
• D-dimer Test: For Wells’ ≤4; positive result warrants further testing (CTPA)
• Alternative Imaging: For patients with contraindications to CTPA, consider V/Q SPECT or planar scan, along with interim anticoagulation if delayed

• Clinically suspected DVT: 3.0 points
• Alternative diagnosis less likely than PE: 3.0 points
• Tachycardia (HR >100 bpm): 1.5 points
• Recent immobilization/surgery: 1.5 points
• History of DVT/PE: 1.5 points
• Hemoptysis: 1.0 point
• Malignancy (recent treatment or palliative): 1.0 point
• Interpretation: ≤4 points = PE unlikely; >4 points = PE likely

• Application: Used when PE suspicion is low
• Criteria: All must be absent to rule out PE (negative PERC result)

• Used for patients with Wells’ score ≤4
• Positive D-dimer prompts further testing (CTPA)
• Negative D-dimer reduces PE likelihood, leading to consideration of alternative diagnoses

• For patients with contraindications to CTPA (e.g., contrast allergy, severe renal impairment, high radiation risk)
• Consider V/Q SPECT or planar scan as alternatives

• Consider alternative diagnoses if no PE is found and no DVT is suspected

• Cancer Investigation: Physical exam, CXR, blood tests, urinalysis, abdomino-pelvic CT scan, and mammogram (for women >40)
• Antiphospholipid Antibody Testing: If planning to stop anticoagulation
• Hereditary Thrombophilia Testing: For patients with unprovoked PE and a first-degree relative with DVT/PE

• D-dimer blood test: Assesses the likelihood of a clot; elevated levels suggest thrombosis, especially useful in low-risk cases
• Computed Tomography Pulmonary Angiography (CTPA): Preferred imaging modality, provides speed and diagnostic accuracy, considered the gold standard
• Ventilation-Perfusion (V/Q) scan: Reserved for cases where CTPA is contraindicated
• Chest X-ray (CXR): Often normal but can reveal signs such as decreased vascular markings, atelectasis, or pleural effusion

• Electrocardiography (ECG): Identifies signs of right heart strain or ischemia, common changes include sinus tachycardia, atrial fibrillation, and the S1Q3T3 pattern
• Echocardiography: Assesses heart function and may detect thrombus in proximal pulmonary arteries
• Blood tests: Includes Troponin to assess cardiac damage and baseline tests such as FBC, Biochemistry, and Clotting Screen
• Arterial Blood Gases (ABG): Assesses oxygenation status, may show hypoxia in severe cases

• The PERC rule (Pulmonary Embolism Rule-out Criteria) helps rule out PE in low-risk patients when all criteria are negative, reducing the need for further testing

• Leg ultrasound is useful for detecting co-existing deep vein thrombosis (DVT) and may be sufficient if clinical DVT is present

• Clinical likelihood, patient condition, and test availability guide the selection and sequencing of investigations for PE

• Direct Oral Anticoagulants (DOACs) such as apixaban or rivaroxaban are the first-line treatment

• Used in high-risk or hemodynamically unstable patients, particularly in cases of massive PE

• Oxygen therapy to maintain oxygen saturation within target ranges (94-98%)
• Pain relief and close monitoring

• Considered when anticoagulation is contraindicated or has failed
• Removal should be planned when clinically appropriate

• Immediate thrombolysis (e.g., alteplase)
• Intravenous access and resuscitation
• Heparin treatment is initiated

• Pregnancy: Higher risk of PE; breathlessness is interpreted cautiously
• Catamenial Pneumothorax: Managed with surgery and hormonal treatment
• HIV infection: Early drainage and surgical referral
• Cystic fibrosis: Early treatment and surgical referral

• Warfarin is often prescribed with Low Molecular Weight Heparin (LMWH) until INR reaches a therapeutic range

• Shift towards using DOACs as first-line treatment and outpatient care for low-risk cases
• Treatment decisions are based on patient risk factors, clinical condition, and comorbidities

• NICE recommends DOACs as first-line treatment for most VTE cases
• Emphasizes timely VTE prophylaxis, risk assessment for patients with lower-limb immobilization, and regular review of anticoagulation treatment

• Considered for high-risk or select intermediate- to high-risk PE cases when thrombolysis is not possible or ineffective
• May also be performed in patients with certain right heart thrombi

Prognosis is influenced by:
– Size and location of the clot
– Severity of symptoms
– Comorbidities (e.g., cancer, heart failure)
– Timeliness of treatment
– Effectiveness of treatment

Risk factors for a poor prognosis include:
– Age >70 years
– Cancer
– Heart failure or COPD
– Hypotension
– Tachypnea
– Right ventricular dysfunction on echocardiography

Severe or untreated PE can lead to:
– Chronic thromboembolic pulmonary hypertension (CTEPH)
– Recurrent embolism
– Death in critical cases

With early and appropriate treatment, the prognosis for PE is generally good

1. Cardiovascular Complications:
– Right heart strain
– Right heart failure
– Shock due to compromised cardiac output and reduced blood pressure
2. Pulmonary Complications:
– Chronic thromboembolic pulmonary hypertension (CTEPH)
– Respiratory failure
– Pulmonary infarction
– Pneumonia
3. Thromboembolic Complications:
– Recurrent embolism
– Deep vein thrombosis (DVT) or post-thrombotic syndrome
4. Anticoagulant Therapy Complications:
– Bleeding complications from anticoagulant therapy