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Pulmonary embolism: Difference between revisions

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Pulmonary embolism (view source)

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In patients with low pre-test probability, the pulmonary embolism rule-out criteria (PERC) may be applied. If all these eight criteria are fulfilled, PE is excluded, and D-dimer testing is not necessary.
In patients with low pre-test probability, the pulmonary embolism rule-out criteria (PERC) may be applied. If all these eight criteria are fulfilled, PE is excluded, and D-dimer testing is not necessary.


=== Clinical findings ===
Pulmonary embolism causes a sudden increased load on the right ventricle, which may manifest on the [[Electrocardiography|ECG]]. These ECG findings are not specific for PE, but most people with PE have one or more ECG abnormality. Some of the possible signs include:
Pulmonary embolism causes a sudden increased load on the right ventricle, which may manifest on the [[Electrocardiography|ECG]]. These ECG findings are not specific for PE, but most people with PE have one or more ECG abnormality. Some of the possible signs include:


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* SIQIIITIII-pattern (S-wave in I, Q-wave in III, and T inversion in III)
* SIQIIITIII-pattern (S-wave in I, Q-wave in III, and T inversion in III)
* [[Right bundle branch block|RBBB]]
* [[Right bundle branch block|RBBB]]
[[Arterial blood gas]] may show hypocapnia and hypoxaemia. [[Troponin|Troponins]] and <abbr>[[NT-proBNP]]</abbr> may be positive due to the strain on the heart.
=== Imaging ===
The gold standard for PE diagnosis is [[CT pulmonary angiography]] (CTPA), a rapid sequence with IV contrast where the CT scanner spirals around the patient in one breath hold. The scan itself takes only seconds, but the whole procedure including administration of contrast and set-up takes up to 10 minutes.
CTPA shows pulmonary emboli as partial or complete filling defects located within the contrast-enhanced lumens of the pulmonary arteries. It's a highly specific and sensitive examination for PE.
An alternative to CTPA is V/Q scan, but this is rarely needed.


[[Echocardiography]] is useful in PE, as it allows for ruling out other differential diagnoses ([[Cardiac tamponade|tamponade]], myocardial ischaemia, valvular disease, etc.), and in case of massive PE right ventricular strain may be visible.
[[Echocardiography]] is useful in PE, as it allows for ruling out other differential diagnoses ([[Cardiac tamponade|tamponade]], myocardial ischaemia, valvular disease, etc.), and in case of massive PE right ventricular strain may be visible.


[[Arterial blood gas]] may show hypocapnia and hypoxaemia. [[Troponin|Troponins]] and <abbr>[[NT-proBNP]]</abbr> may be positive due to the strain on the heart.
Chest radiography is not used for evaluation of PE, but in 2% of cases, the Westermark sign may be present. This is only seen in large emboli and is characterised by the distal blood vessels of a lung being collapsed and therefore smaller than normal, called focal peripheral hyperlucency.
 
The gold standard for PE diagnosis is [[CT pulmonary angiography]] (CTPA), a rapid sequence with IV contrast. The scan itself takes only seconds, but the whole procedure including administration of contrast and set-up takes up to 10 minutes. An alternative to CTPA is V/Q scan.


== Treatment ==
== Treatment ==