Pulmonary embolus

Question 1

How common is it?

Answer 1

In patients younger than 55 years, the incidence of pulmonary embolism is higher in females. The overall age- and sex-adjusted annual incidence of venous thromboembolism is reported to be 117 cases per 100,000 people in the US.

Question 2

What causes pulmonary embolism?

Answer 2

The thrombus is usually formed in the systemic veins (or in the right heart <10%). Said thrombus becomes lodged in the pulmonary arterial system, occluding the flow of blood to the lungs. Lung tissue is ventilated but not perfused, producing an intrapulmonary dead space resulting in impaired gas exchange. The primary haemodynamic consequence is a reduction in the cross-sectional area of the pulmonary arterial bed which results in an elevation of pulmonary arterial pressure and reduction in cardiac output.

Question 3

What are the risk factors for pulmonary embolism?

Answer 3

Age
BMI>30
Varicose veins
Continuous travel >3h in preceeding 4 weeks
Immobility (bedrest >3 days)
Previous VTE
Thrombophilia
Oestrogen therapy
Trauma/surgery
Malignancy
Cardiac or respiratory failure
Recent MI/stroke
Etc etc etc...

Question 4

What is the presentation of pulmonary embolism?

Answer 4

Small/medium PE:

• pleuritic chest pain
• breathlessness
• haemoptysis (in 30%, often >3 days afterwards)

Massive PE:

• sudden syncope (acute occlusion of right ventricular tract)
• severe central chest pain
• shock

Multiple recurrent PE:

• increased breathlessness over weeks
• weakness
• syncope on exertion
• occasionally angina

Question 5

What are the clinical signs of pulmonary embolism?

Answer 5

Small/medium PE:

• tachypnoeia
• localised pleural rub
• coarse crackles

Massive PE:

• tachypnoeia
• tachycardia
• hypotension
• peripheral shutdown
• raised JVP
• prominent a wave
• right ventricular heave
• gallop rhythm
• widely split second heart sound

Multiple recurrent PE:

• right ventricular heave
• loud pulmonary second shout

Question 6

What are the differential diagnoses?

Answer 6

Acute Coronary Syndrome
Acute Pericarditis
Acute Respiratory Distress Syndrome
Angina Pectoris
Anxiety Disorders
Aortic Stenosis
Atrial Fibrillation
Cardiogenic Shock
Cor Pulmonale
Dilated Cardiomyopathy
Emphysema
Fat Embolism
Hypersensitivity Pneumonitis
Mitral Stenosis
Myocardial Infarction
Pneumothorax Imaging
Idiopathic Pulmonary Arterial Hypertension
Pulmonary Arteriovenous Fistulae
Restrictive Cardiomyopathy
Nonidiopathic Pulmonary Hypertension
Sudden Cardiac Death
Superior Vena Cava Syndrome in Emergency Medicine
Syncope

Question 7

What investigations would you perform?

Answer 7

Small/medium PE:

• CXR (often normal)
• ECG (usually normal, sometimes AF)
• FBC (polymophonuclear leucocytosis, elevated ESR and lactate dehydrogenase)
• Plasma D-dimer (if undetectable it excludes PE)
• Radionuclide ventilation/perfusion scanning
• US
• CT angiography (MR if CT contraindicated)

Massive PE:

• CXR (may show pulmonary oligaemia with dilatation of pulmonary artery in the hila, or may be normal)
• ECG (tall peaked P waves in lead II, right axis deviation, some right bundle branch block, t wave inversion in right precordial leads
• Blood gases (arterial hypoxaemia, with low arterial CO2, i.e. type II respiratory failure pattern)
• Echocardiography (vigorously contracting left ventricle and sometimes dilated right)
• CT/MR angiography

Question 8

How would you explain the condition to the patient?

Answer 8

A blood clot, formed in the leg/pelvic veins has broken off and lodged in one of the arteries that supplies the lungs. This can be treated with ‘clot busting’ drugs.

Question 9

What is the revised Geneva score for pulmonary embolism?

Answer 9

Risk factors:

• Age >65yrs +1
• Previous DVT or PE +3
• Surgery or fracture within 1 month +2
• Active malignancy +2

Symptoms:

• Unilateral leg pain +3
• Haemoptysis +2

Clinical signs:

• Heart rate
• • 75-94 bpm +3
• • > 95 bpm +5
• Pain on leg deep vein palpation and unilateral oedema +4

Clinical probability:

• Low 0-3
• Medium 4-10
• High >11

Question 10

What acute treatment would you discuss?

Answer 10

High flow O2 (60-100%)

SC low molecular weight heparin or fondaparinux or IV unfractionated heparin followed by warfarin therapy

For massive PE:

• IV fluids
• sometimes inotropic agents to improve pumping of R heart

Fibronolytic therapy:

• Streptokinase
• For use in unstable pts and massive PE

Surgical embolectomy:

• rarely necessary
• for when haemodynamic circumstances are very severe