Pulmonary Embolism

Question 1

What is a PE?

Answer 1

Clot in pulmonary arterial tree with subsequent increase in pulmonary vascular resistance, impaired V/Q matching and +/- reduced pulmonary blood flow.

Question 2

What is Virchow’s triad?

Answer 2

• Stasis
• Hypercoaguability
• Endothelial injury

Question 3

Source of most thrombi causing clinically recognised PEs?

Answer 3

• Politeal vein
• femoral vein
• Iliac vein

Question 4

What symptoms warrant PE exclusion 1-2/52 post op?

Answer 4

• Fever
• Sudden dyspnoea
• CP
• Collapse

Question 5

When should D-dimer be used as first line in ?PE evaluation?

Answer 5

When pretest probability low / low clinical suspicion of PE.

Highly sensitive; can exclude DVT/PE if pretest probability already low.

Question 6

Ix in ?PE evaluation?

Answer 6

• CT angiogram
• D-dimer
• Venous duplex u/s
• ECG
• CXR
• V/Q scan

Question 7

What is D-dimer?

Answer 7

Products of thrombotic/fibrinolytic process.

Question 8

Is CT angio helpful in PE evaluation?

Answer 8

Yes: sensitive and specific.

May identify alternative diagnosis if not PE.

Question 9

ECG signs of massive PE?

Answer 9

• RV strain
• RBBB
• S1-Q3-T3 with massive embolisation

Question 10

CXR signs of PE?

Answer 10

-Often NAD; no specific features
- atelectasis (subsegmental), elevation of a hemidiaphragm
ƒ-pleural effusion: usually small
ƒ-Hampton’s hump: cone-shaped area of peripheral opacification-> infarction ƒ
-Westermark’s sign: dilated proximal pulmonary artery w/ distal oligemia/decreased
vascular markings (difficult to assess without prior films)
ƒ-dilatation of proximal PA: rare

Question 11

When should V/Q be done in ?PE eval?

Answer 11

• CXR normal, no COPD

- CT contraindicated (allergy, renal dysfunction, pregnancy)

Question 12

When should V/Q be avoided in ?PE eval?

Answer 12

• CXR abnormal or COPD
• inpatient
• suspect massive PE

Question 13

When is D-dimer elevated?

Answer 13

• Recent surgery
• Cancer
• inflammation
• infection
• severe renal dysfunction

Question 14

Explain D-dimer in relation to sens/spec, NPV and PPV

Answer 14

Good: sensitivity and NPV
Poor: specificity and PPV

Question 15

Treatment PE?

Answer 15

• 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)

Question 16

Purpose of anticoagulation in PE?

Answer 16

• Stops clot propagation
• Prevents new clots
• Enables endogenous fibrinolysis to dissolve existing thromboemobli over months

Question 17

Test to order when staring anticoagulation?

Answer 17

Baseline:

• FBE
• UEC
• INR
• aPTT
• LFTs

Question 18

Clexane dose in PE?

Answer 18

1mg/kg bid

Question 19

IV heparin in PE?

Answer 19

• Bolus 75U/kg (usually 5000U)

- Infusion 20U/kg/h

Question 20

aPTT aim post PE?

Answer 20

2-3x control

Question 21

How should warfarin be commenced post PE?

Answer 21

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

Question 22

Sources of PE other than thrombosis?

Answer 22

• Fat e.g. post trauma
• Air e.g. post lap surgery
• Amniotic fluid

Question 23

How is PE probability determined clinically?

Answer 23

Wells criteria used to identify PE probability using clinical assessment.