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Pulmonary Embolism

Dr Antony Crockett advises on key diagnostic signs and pitfalls

Dr Antony Crockett advises on key diagnostic signs and pitfalls

Worst outcomes if missed

  • Death Mortality can be reduced from 30 per cent in untreated cases to below 10 per cent by rapid and effective treatment.
  • Pulmonary hypertension Up to 30 per cent of patients who have had a massive pulmonary embolus (PE) may develop pulmonary hypertension, even if promptly treated.
  • Right ventricular failure May be a complication of pulmonary hypertension, causing more severe breathlessness and peripheral oedema. Right ventricular failure may also result in additional left ventricular failure.
  • Recurrence Mortality from untreated recurrent PE may rise to 30 per cent.

Epidemiology and incidence

PE is usually due to a thrombus from the venous circulation embolising to the pulmonary arterial circulation. Thrombi usually arise in the calf veins, but can arise in the pulmonary arteries, as can happen during crises in patients with sickle cell anaemia.

Septic thrombi can arise from endocarditis of the right-sided heart valves, and particulate thrombi or air emboli can arise from intravenous injections.There are approximately 65,000 cases each year in the UK, which is roughly 1-1.7 per 1,000 population. The overall mortality ranges from 10 to 30 per cent.

Risk factors

There are many factors that may increase the risks of developing a PE. Many patients may have several risk factors (eg an obese smoker who has had a hip operation):

  • Prolonged immobilisation, such as a long journey
  • Recovery from surgery, especially if the operation was long, or the surgery was to the pelvis or abdomen or the lower limbs
  • Any trauma to the lower limbs
  • Previous history of DVT or PE
  • Pregnancy, early puerperium
  • Medications, especially oestrogens, including combined oral contraceptive pills and combined HRT
  • Any malignancy, especially visceral cancers, such as those of the lung, pancreas, alimentary or genitourinary tracts, or breast cancer
  • Any trauma; burns; dehydration
  • Systemic diseases, eg diabetes and COPD
  • Many haematological disorders, especially those affecting clotting – protein C or S deficiencies, lupus anticoagulant, polycythaemia rubra vera, factor V Leiden deficiency, antithrombin III deficiency

Symptoms and signs

1 Massive pulmonary embolism

  • Cardiovascular collapse – severe dyspnoea, tachycardia, hypotension and cyanosis
  • The first signs may be syncope or sudden death in the most severe cases

2 Smaller pulmonary embolism

  • The symptoms and signs will depend on the size of the embolus – very small emboli may produce no signs
  • Dyspnoea is the commonest symptom, is usually of sudden or rapid onset, is worse on exertion and may not be apparent at rest
  • Chest pain – usually sudden onset and may be pleuritic; typical chest pains may be absent; chest pains usually occur at a later stage rather than at the acute event
  • Cough, usually dry, difficult to suppress
  • Haemoptysis may be present at a later stage, and is sometimes massive and fatal
  • Sweating, fever, apprehension and fear may all occur in any combination
  • There may be evidence of a deep vein thrombosis, usually in the calf veins
  • Tachypnoea is the commonest sign, often accompanied by tachycardia
  • Examination of the chest may reveal a friction rub, localised wheezing or rales
  • Cardiovascular examination may reveal an elevated jugular venous pulse, resting tachycardia and a loud second heart sound

See boxes (below) for key questions to ask and pitfalls to avoid.

Differential diagnosis

  • Myocardial infarction
  • Chest wall pain
  • Pneumonia
  • Pleurisy
  • Anxiety with hyperventilation
  • Dyspepsia, gastro-oesophageal reflux, cholecystitis
  • Pneumothorax
  • Pericarditis
  • Congestive heart failure

First-line investigations

If PE is suspected, the sooner the diagnosis is made and treatment started the better. First-line tests are limited in primary care to:

  • ECG – will usually show tachycardia if a PE is present; in more severe cases there will be evidence of right heart strain (S1Q1T1 configuration); right axis deviation and atrial fibrillation may also occur
  • Pulse oximetry – hypoxia is a cardinal feature and significant PE will nearly always result in saturation of 92 per cent or less.

Second-line investigations

  • Chest X-ray
  • Plasma D-dimer measurement
  • Ventilation-perfusion scan

Antony Crockett is a GP and hospital practitioner in respiratory medicine in Shrivenham, Wiltshire. Competing interests: none declared

Five key questions to ask

1 Have you been on any long journeys, or been bedridden, or immobile for any length of time recently?

2 Do you have any pain or swelling in your calves or elsewhere in your arms or legs?

3 Are you feeling breathless or do you get breathless on exertion?

4 Have you ever had any problems with blood clots, or had a deep vein thrombosis or pulmonary embolus in the past, or ever needed warfarin?

5 Are you on the Pill or on HRT (if patient is female), and do you smoke?

Five red herrings

1 The presence or absence of focal pleuritic pain will neither diagnose nor exclude possible PE – pleuritic pain may not be apparent in the early stages, and very often is not a feature at all even when a PE has been proven. Pleuritic-type pain is not uncommonly presented in primary care and most cases are minor chest wall problems or non-serious infections.

2 A normal chest examination does not exclude a PE – the diagnosis must be suspected on the basis of a good history.

3 Many patients with anxiety will present with dyspnoea and tachycardia and even chest pains – an acute PE may result in similar symptoms as well as causing great anxiety. Anxiety is a possible differential diagnosis.

4 Economy-class flights are popularly assumed to be a major cause of DVTs and PEs, but the risk factor is relatively prolonged immobility together with dehydration, and DVT and PE are quite unusual sequelae of flying in patients with no other risk factors. Their frequency is not significantly affected by flying economy-class compared with business- or first-class.

5 Initial investigations (ECG and oximetry) done in the surgery may be normal. If PE is suspected refer immediately.

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