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Pulmonary Embolus

Introduction

Cause usually:
- venous thromboembolism

Rarely
- fat
- amniotic fluid
- injected material (IVDU)

Risk factors
- as for DVT

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Clinical features: acute PE

Small PE
- pleurisy (without dyspnoea)
- haemoptysis

Large PE
- respiratory distress (dyspnoea, hypoxia)
- acute R heart strain (­JVP, L parasternal heave)

Massive / saddle PE
- engorged neck veins
- RV gallop
- collapse
- cardiorespiratory arrest

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Clinical features: chronic PE

Multiple small PE
- progressive dyspnoea
- cyanosis
- pulmonary HTN (JVP, left parasternal heave, oedema)

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Well's score

3.0: Clinical symptoms of DVT
3.0: No alternative diagnosis

1.5: previous history of DVT / PE
1.5: Surgery / immobilisation in last 4 weeks
1.5: HR > 100

1.0 Haemoptysis
1.0 Cancer

< 2 = low probability
2 – 6 = moderate probability
> 6 = high probability

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Investigation

Routine Ix
ABGs
- V:Q mismatch (decreased PaO2)
- A-a gradient
- tachypnoea (decreased PaCO2)

CXR *
- normal
- consolidation (peripheral, wedge-shaped)
- pulmonary oligaemia (Westermark's sign)

ECG *
- usually (sinus tachycardia, minor ST / T abnormalities)
- acute RV strain (S1,Q3,T3 = 'classic' sign, but rarely seen!, RBBB, AF)

* main reason for doing CXR & ECG is to exclude alternative diagnosis

Special Ix
D-dimers
- clinical 'low' probability: can reliably exclude PE (e.g. Wells’ < 4 with -ve D-dimers = ~ 2 % PE)
- clinical 'high' probability: should NOT be performed

Leg USS
- cannot exclude PE
- can confirm VTE (if clinical DVT)

V/Q scan *
- if normal CXR (and no severe COPD or asthma)
- N scan: can exclude PE (PIOPET = < 3 % PE)
- mismatched Q defect: ? PE, high false +ve

BUT...
- 75 % results are low / indeterminate probability

CTPA **
- modern goldstandard (replacing pulmonary angiography)

Cardiac echo
- alternative to CTPA for massive PE

* ventilation-perfusion lung scintogram (can use CXR as surrogate Q scan)
** spiral CT pulmonary angiography

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Management: suspected massive PE

A
B: 100 % O2
C

- Heparin (IV) UFH: 80 U/kg
- Urgent Ix *: CTPA / echo within 1 hour
- Thrombolysis: rt-PA (alteplase)
- Selected cases: thromboembolectomy, IVC filter

* can thrombolyse on clinical grounds alone if imminent cardiorespiratory arrest

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Management: suspected small-moderate PE

Heparin
- s/c LMWH

Investigations
- imaging within 24 h.

Load Warfarin
- target INR = 2.0 – 3.0
- discontinue heparin (when Warfarin loaded)

Continue Warfarin
- temporary RFs: Warfarin ´ 4 – 6 weeks
- 1st idiopathic PE: Warfarin ´ 3 months
- else: Warfarin ´ > 6 months

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Management: recurrent PE

Thrombophilia screen if:
- <50years old & recurrent PE
- strong family history of proven PE

Management
- warfarin
- cardiology referral

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