Pulmonary Embolism Flashcards
What is a PE?
Clot in pulmonary arterial tree with subsequent increase in pulmonary vascular resistance, impaired V/Q matching and +/- reduced pulmonary blood flow.
What is Virchow’s triad?
- Stasis
- Hypercoaguability
- Endothelial injury
Source of most thrombi causing clinically recognised PEs?
- Politeal vein
- femoral vein
- Iliac vein
What symptoms warrant PE exclusion 1-2/52 post op?
- Fever
- Sudden dyspnoea
- CP
- Collapse
When should D-dimer be used as first line in ?PE evaluation?
When pretest probability low / low clinical suspicion of PE.
Highly sensitive; can exclude DVT/PE if pretest probability already low.
Ix in ?PE evaluation?
- CT angiogram
- D-dimer
- Venous duplex u/s
- ECG
- CXR
- V/Q scan
What is D-dimer?
Products of thrombotic/fibrinolytic process.
Is CT angio helpful in PE evaluation?
Yes: sensitive and specific.
May identify alternative diagnosis if not PE.
ECG signs of massive PE?
- RV strain
- RBBB
- S1-Q3-T3 with massive embolisation
CXR signs of PE?
-Often NAD; no specific features
- atelectasis (subsegmental), elevation of a hemidiaphragm
-pleural effusion: usually small
-Hampton’s hump: cone-shaped area of peripheral opacification-> infarction
-Westermark’s sign: dilated proximal pulmonary artery w/ distal oligemia/decreased
vascular markings (difficult to assess without prior films)
-dilatation of proximal PA: rare
When should V/Q be done in ?PE eval?
- CXR normal, no COPD
- CT contraindicated (allergy, renal dysfunction, pregnancy)
When should V/Q be avoided in ?PE eval?
- CXR abnormal or COPD
- inpatient
- suspect massive PE
When is D-dimer elevated?
- Recent surgery
- Cancer
- inflammation
- infection
- severe renal dysfunction
Explain D-dimer in relation to sens/spec, NPV and PPV
Good: sensitivity and NPV
Poor: specificity and PPV
Treatment PE?
- Admit and observe
- O2 / resp support
- Analgesia (if CP)
- acute anticoagulation
- long term anticoagulation
- IV thrombolytic / interventional thrombolytic therapy
- IVC filter (if DVT + absolute CIx to anticoagulation)
Purpose of anticoagulation in PE?
- Stops clot propagation
- Prevents new clots
- Enables endogenous fibrinolysis to dissolve existing thromboemobli over months
Test to order when staring anticoagulation?
Baseline:
- FBE
- UEC
- INR
- aPTT
- LFTs
Clexane dose in PE?
1mg/kg bid
IV heparin in PE?
- Bolus 75U/kg (usually 5000U)
- Infusion 20U/kg/h
aPTT aim post PE?
2-3x control
How should warfarin be commenced post PE?
start the same day as LMWH/heparin – overlap warfarin with LMWH/heparin for at least 5 d and aim INR 2-3 for at least 2 d
Sources of PE other than thrombosis?
- Fat e.g. post trauma
- Air e.g. post lap surgery
- Amniotic fluid
How is PE probability determined clinically?
Wells criteria used to identify PE probability using clinical assessment.
