Pulmonary Embolism (PE) - Venous Thromboembolism

Pulmonary Embolism (PE)

·        Very important to do a risk assessment for everyone in hospital or bed-bound at home: are they low, medium or high risk. Prevention is better than cure

Presentation

·        Frequently undiagnosed (71% of PEs are not diagnosed): always have it as a differential to SOB 

·        If episodic SOB unresponsive to treatment ® ?PE

·        May not have chest pain.  May have fever, but rarely sweating or rigours

·        Severity:

o   Small: transient chest pain, cough, SOB. If pre-existing pulmonary disease may get small infarct with pleuretic chest pain and fever

o   Multiple small emboli: pleuretic chest pain, haemoptysis, gradually ­SOB

o   Medium: Bronchial arteries are enough to maintain viability of healthy lung tissue. Get chest pain (not always pleuretic), SOB, maybe haemoptysis

o   Large: Classical – 10 days post op, sudden SOB and collapse while straining on toilet. If fatal, die within an hour. May mimic MI with comma (acute SOB, severe chest pain, hypotension, temp, ­LDH, syncope). Also cyanosis, gallop rhythm, ­JVP, pleural rub, haemoptysis

·        Course: Frequent PE ® pulmonary hypertension ® dilated pulmonary artery ® enlarged right heart (Cor Pulmonale)

Possible Investigations

·        Imaging:

o  CXR: most are normal

o  Doppler US for DVT

o  Ventilation-Perfusion Scan

o  Pulmonary arteriogram: gold standard but not often done

o  CT Pulmonary Angiogram: pretty good and getting better

·        ECG: 

o  Small-medium PE: usually normal except for tachycardia. May be signs of AF or right ventricular strain 

o  Massive PE: S1Q3T3 pattern: S wave in lead I, Q wave in lead III, inverted T wave in lead III. Tall peaked T waves in lead II.

·        Bloods:

o  ABGs: Aa gradient

o  FBC - check Hb, WBCs, platelets (eg ­ ® hypercoagulable)

o  Clotting times: likely to be normal – these test bleeding disorders, not clotting disorders 

·        D-dimmer test for fibrin degradation products ® digested clot (cheap and easy):

o  +ive for cancer, trauma, post surgery, sepsis ® lots of false positives

o  Don‟t use as first line test – only in the context of a complete algorithm

·        Decision analysis:

o  If > 6% risk of a PE then test

o  If > 48% risk of a PE then treat

o  If risk > 6% but < 48% then further testing

o  Test sequence:

§  Chest X-ray and D-dimmer: if d-dimmer negative then no DVT/PE. Positive test doesn‟t change pre-test odds. If Chest X-ray normal then V/Q scan. If abnormal go straight to CT angiogram 

§  V/Q Scan: if positive then treat.  If negative, doesn‟t change pre-test odds

§  CT angiogram

Treatment

·        Anticoagulant Treatment

·        If massive (Hypotension and multiple clots): thrombolysis or surgery

·        If submassive (RV strain or lots of clots): consider thrombolysis