QuestionSBA
QuestionChoice
Myocardial infarction does present with chest pain, however it is characteristically a crushing chest pain radiating to the left arm and jaw. In this case the pain is more pleuritic, which is more in keeping with a pulmonary cause. There may or may not be signs on physical examination, ECG or chest x-ray in myocardial infarction however this patient has significant risk factors for pulmonary embolism rather than myocardial infarction, therefore in the context of the clinical history pulmonary embolism is more likely
33559
b
Myocardial infarction
QuestionChoice
Pericarditis typically presents with pleuritic chest pain as in this case. However, this typically has characteristic ECG signs (PR depression and widespread saddle shaped ST elevation), which were not present in this case. In the presence of sudden onset chest pain with significant risk factors for PE and an ECG showing tachycardia, a pulmonary embolism is the more likely diagnosis
33561
d
Pericarditis
QuestionChoice
Pneumonia can present with pleuritic chest pain, as described in this case. However, this is less likely to be of sudden onset and will probably be associated with other features including fever and a productive cough of green/rust coloured sputum. Most significantly, the chest x-ray is normal for this patient. In pneumonia, there are usually radiological features on the chest x-ray
33560
c
Pneumonia
QuestionChoice
Anxiety is a good differential in this case. It can present with chest pain and sinus tachycardia and should be considered if investigations are normal. However, pulmonary embolism can also present with the same physical examination and investigation results and the fact that this is sudden onset and in the presence of a significant risk factor increases the suspicion that this presentation is due to a pulmonary embolism. Therefore, pulmonary embolism should be considered above anxiety, until pulmonary embolism has either been confirmed or adequately ruled out
33562
e
Anxiety
QuestionChoice
There are several features in this case that suggest a diagnosis of pulmonary embolism. Pleuritic chest pain is a typical feature of pulmonary diseases, including pulmonary embolism. In addition, the symptoms of a pulmonary embolism are typically described as being sudden onset. Tachycardia is another typical feature. Pulmonary embolism often has no signs on physical examination or chest x-ray. This patient has a significant risk factor of recent surgery and as they are on no current medications they may not have been prescribed any thromboprophylaxis (e.g. low molecular weight heparin). Notably, there are several typical features absent from this presentation including no haemoptysis and no clinically obvious deep vein thrombosis (DVT). The absence of these features, does not rule out a pulmonary embolism
33558
a
Pulmonary embolism
Concept
Chapter
# Definition

A pulmonary embolism (PE) is when a blood clot in the pulmonary arterial vasculature develops, usually from an underlying deep vein thrombosis (DVT) of the lower limbs.

# Epidemiology of pulmonary embolism (PE)

2300 people died as a result of a pulmonary embolism in the UK in 2012, representing 2% of all deaths from lung diseases.

# Presentation of a PE

**Symptoms**

- Sudden-onset shortness of breath, pleuritic chest pain, and haemoptysis (this is the 'typical' triad, although note that all three features are rarely present).

- A massive pulmonary embolism may present with the above and syncope/shock.

- A small pulmonary embolism may be asymptomatic.

**Signs**

- Classically tachypnoea, tachycardia and hypoxia is present. There may be low-grade pyrexia. Tachycardia may be the only presenting sign.

- Note that a small pulmonary embolism may result in a normal examination.

- A massive pulmonary embolism may present with hypotension, cyanosis, and signs of right heart strain (such as a raised JVP, parasternal heave, and loud P2).

It is important to look for signs of a concomitant deep vein thrombosis (a unilaterally swollen, tender calf).

# ECG findings

ECG: Normal or sinus tachycardia. In a massive PE there may be evidence of right-heart strain (with P pulmonale, right axis deviation, right bundle branch block, and non-specific ST/T wave changes). The classic S1Q3T3 (deep S waves in lead I, pathological Q waves in lead III, and inverted T waves in lead III) is relatively uncommon (<20% of patients).

# Blood tests in PE

ABG: This may be normal or show a type 1 respiratory failure (hypoxia without hypercapnia) and/or a respiratory alkalosis (due to hyperventilation secondary to hypoxia).

Remember the baseline tests such as FBC (the patient may be anaemic if the PE has caused haemoptysis), CRP may be raised, U&E (to assess renal function before CTPA), clotting function (important if the patient is to be started on LMWH/Warfarin).

Special tests include D-dimer (this is highly non-specific but has a 95% negative predictive value i.e. it is useful in ruling out a PE if negative).

# Imaging Investigations in PE

Chest x-ray: this is typically normal in PE but possible findings include _Fleischner sign_ (an enlarged pulmonary artery), _Hampton's hump_ (a peripheral wedge shaped opacity), and _Westermark's sign_ (regional oligaemia). The chest x-ray is helpful in ruling out differentials (e.g. pneumonia, pneumothorax).

CT pulmonary angiogram (CTPA): this is the diagnostic test of choice for a PE and will show a filling defect in the pulmonary vasculature. Note that a V/Q scan is preferred if the patient has renal impairment, contrast allergy or is pregnant.

Lower limb Duplex: helpful if a DVT is thought to be the cause of the PE (note this investigation is first-line - before a CTPA - in pregnancy).

Bedside echocardiogram: this is used if the patient is thought to have a massive PE (signs of right heart strain/hypotension), in order to assess suitability for thrombolysis.

# Well's scoring system

The Well's score is a useful tool for risk stratifying patients with a suspected PE.

Points are allocated as follows:

- 3 points:
  - Clinical signs and symptoms of a deep vein thrombosis (DVT)
  - If no alternative diagnosis is more likely than a PE
- 1.5 points:
  - Tachycardia (heart rate >100 beats/minute)
  - If the patient has been immobile for more than 3 days or has had major surgery within the last month
  - If the patient has had a previous PE or DVT
- 1 point:
  - If the patient presents with haemoptysis
  - If there is an active malignancy

If the Well's score is 4 or less the D-dimer should be measured. The D-dimer has a high negative predictive value but a low specificity so is only useful if the clinical suspicion of a PE is low.

A low D-dimer excludes a PE. A raised D-dimer is an indication for diagnostic imaging (by CTPA or V/Q scan).

If the Well's score is more than 4 further diagnostic imaging is required. Low-molecular weight heparin is typically administered in the interim if the clinical suspicion of a PE is high (and should certainly be administered if there is delay in performing the CTPA).

# Acute management of a PE

In the emergency department the patient should be assessed using the DR ABCDE approach:

- Airway: likely to be patent.
- Breathing: the patient may be tachypnoeic and hypoxic. Oxygen should be administered.
- Circulation: the patient may be tachycardic. Signs of right heart strain are suggestive of a sub-massive PE. Hypotension is suggestive of a massive PE. Consider intravenous fluids if the systolic blood pressure is <90 mmHg.
- Disability: likely to be unremarkable.
- Exposure: the patient may have a low grade pyrexia. It is important to check for signs of a deep vein thrombosis (DVT). Consider analgesia at this stage if required.

Thrombolysis (an intravenous bolus of Alteplase) is indicated in a massive PE (features of haemodynamic instability). There is debate over whether it should be administered in a sub-massive PE.

# Medical management of a PE

Anticoagulation should be administered.

In the outpatient setting, direct oral anticoagulants such as apixaban or rivaroxaban should be started.

If neither of the above are suitable, dabigatran, edoxaban or warfarin can be considered. Low molecular weight heparin should be continued for at least 5 days and until 48 hours of therapeutic INR (>2) has been achieved if using warfarin. If using dabigatran or edoxaban then LMWH should be used for 5 day prior.

The duration of anticoagulation treatment depends on the aetiology of the PE. A provoked PE (identifiable risk factors e.g. surgery, peri-partum) should be treated for 3 months. An unprovoked PE should be treated for 6 months. If there is an ongoing cause (e.g. a thrombophilia) the patient should be treated for life.

Recurrence of a VTE in a patient already on warfarin requires an increase in the target INR (to 3-4).

In the inpatient/emergency setting, low molecular weight heparin is usually started instead as it is shorter acting.

# Interventional management of a PE

Embolectomy may be considered in patients with a massive PE when thrombolysis is contraindicated.

An inferior vena cava filter may be considered in patients with recurrent DVTs on Warfarin or patients in which anticoagulation is contraindicated.

# References

[Click for the NICE Guidelines](https://www.nice.org.uk/guidance/ng158)
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Pulmonary embolism
Topic
20
Respiratory Physiology
6712
A 54 year old man presents to the emergency department with a 2 hour history of chest pain. The chest pain is a sudden onset, stabbing pain on the right side of his chest, that gets worse when he breathes in. On examination, he has a heart rate of 107/min, respiratory rate of 22/min and is apyrexial. No abnormalities are noted on examination, his chest x-ray is normal, and an ECG shows sinus tachycardia. He has recently been discharged after a bilateral hip replacement surgery 1 week ago and is currently on no medications.

What is the most likely diagnosis?
a