Pulmonary embolism

Question 1

Explain the pathophysiology behind PEs and how they cause sx

Answer 1

1. lung tissue is ventilated but not perfused -> intrapulmonary dead space -> impaired gas exchange
2. Alveolar collapse -> worsens hypoxaemia
3. Reduction in cross sectional area of pulmonary arterial bed -> increased pulmonary arterial pressure + decrease in CO

Question 2

What are the sources of emboli?

Answer 2

DVT in lower limbs 
Prostate + breast cancer (mostly)
Sepsis
Foreign bodies ( IVDU, broken catheters etc)
Air - admitted during surgery 
Amniotic fluid during pregnancy

Question 3

What are the RFs for PE?

Answer 3

DVT
Prev DVT/PE
Active cancer
Recent surgery/trauma
Immobility 
Pregnancy (esp. 6 weeks post party)
>60yrs
COCP, HRT
Obesity

Question 4

What are the clinical features of PE?

Answer 4

1. SOB
2. Tachypnoea
3. Pleuritic chest pain
4. Features of DVT
5. Others:
   - tachycardia
   - haemoptysis
   - syncope
   - hypotension
   - creps
   - cough or fever

Question 5

What investigations would u do in suspected PE?

Answer 5

1. Wells score (2-level)
2. CTPA
3. D-dimer
4. ECG
5. CXR

Question 6

When would you do a CTPA?

Answer 6

if >4 points on Wells score

of if D-dimer +ve

Question 7

When would you do D-dimer?

Answer 7

if 4 or less points on Wells score

Question 8

When are CTPAs contraindicated and what is an alternative?

Answer 8

1. allergy to contrast
2. renal impairment
   use V/Q scan

Question 9

What changes are seen on ECG in PE?

Answer 9

Sinus tachycardia
RBBB + R axis deviation
S1Q3T3 - large S wave, large Q wave, inverted T wave

Question 10

What should be done if there is a. delay in CTPA?

Answer 10

give immediate LMWH or fondaparinux (continue for 5 days)

Question 11

What is the management of PE?

Answer 11

1. LMWH (dalteparin) OR FONDAPARINUX injections ASAP as these start working straight away and bridge the time it takes for warfarin to start working
2. WARFARIN w/in 24hrs of diagnosis, continue for 3 m

Question 12

How long should LMWH/fondaparinux be taken for?

Answer 12

At least 5 days
or
until INR is 2.0 or more or at least 24hrs
WHICHEVER IS LONGER

Question 13

When should warfarin be given for longer than 3m?

Answer 13

if unprovoked PE - so no obvious cause or provoking factor

active cancer - give for 6m

Question 14

what is rx of massive PE w circulatory failure ?

Answer 14

Thrombolysis

Question 15

Give examples of thrombolytic drugs

Answer 15

alteplase
tenecteplase
streptokinase

Question 16

What are differentials of PE?

Answer 16

• Resp: pneumothorax, pneumonia, acute exacerbation of chronic lung disease
• Cardiac: ACS, HF, dissecting or rupturing AA, pericarditis
• MSK chest pain
• GORD
• Pregnancy

Question 17

Give the WELLS criteria

Answer 17

1. Clinical signs + sx of DVT - +3
2. PE is no. diagnosis of equally likely - +3
3. HR >100 - +1.5
4. Immobilisation at least 3 days or surgery in prev. 4 weeks - +1.5
5. Prev PE/DVT - +1.5
6. Haemoptysis - +1
7. Malignancy w rx w/in 6m or palliative - +1