Resp - PE

Question 1

what is PE? suggest different causes

Answer 1

Obstruction within pulmonary arterial tree due to emboli. Can be caused by:

i. thrombosis - 90% thromboemboli form from DVT in legs
ii. fat - following long bone fracture or ortho surgery
iii. amniotic fluid
iv. air - following neck vein cannulation or bronchial trauma
v. tumour cells
vi. foreign material

Question 2

describe 3 possible downstream consequences of large PE on heart and lung function

Answer 2

1. T1RF - blood diversion to unaffected areas which may result in V/Q <1 if hyperventilation cannot match increased perfusion and hypoxaemia.
2. RV overload - increased pulmonary artery pressure (if >30% total cross-section of pulmonary arterial bed occluded) in attempt to maintain systemic BP… RV strain and dilation… decreased CO.
3. Pulmonary infarction - small distal emboli may create areas of alveolar haemorrhage… haemoptysis, pleuritis and small pleural effusions

Question 3

Describe the common signs and symptoms of PE

Answer 3

Symptoms:

• sudden-onset pleuritic chest pain
• SOB
• haemoptysis and cough
• syncope (if severe, due to decreased CO)

Signs:

• tachypnoea, tachycardia
• hypoxia
• raised JVP
• pleural friction rub (if pulmonary infarction)

Question 4

what score can be used to assess likelihood of PE?

Answer 4

Well’s score:

1) clinically suspected DVT (leg swelling and pain on deep vein palpation): 3 pts
2) alternative Dx are less likely than PE: 3 pts
3) tachycardia (>100 bpm): 1.5 pts
4) immobilisation >3 days or surgery in prev. 4 wks: 1.5 pts
5) Hx of DVT or PE: 1.5 pts
6) haemoptysis: 1 pt
7) malignancy (on Tx in preceding 6 mths or palliative stage): 1 pt

Clinical probability:

• 4 pts or less: PE unlikely
• > 4 pts: PE likely

Question 5

which investigations would you request for a pt with suspected PE?

Answer 5

1. Bloods:
   - baseline FBC, UandE and clotting screen
   - cardiac troponin: rule of MI
   - BNP levels: if raised, might indicated RV strain
   - D-dimer: can exclude DVT/PE if low
   - ABG: may show reduced PaO2 and reduced PaCO2 due to hyperventilation or acidosis
2. Bedside tests:
   - ECG: may be normal or abnormal
3. Imaging:
   - CXR: exclude pneumonia. Usually normal in PE but may show: decreased vascular markings, atelectasis, small pleural effusion or Hampton’s hump in late PE
   - leg USS: if DVT suspected
   - CT-PA: shows filling defect if PE
   - V/Q scan: alternative to CT-PA

Question 6

how would you manage a pt with PE?

Answer 6

1. Supportive: O2 therapy if hypoxaemic, IV fluid if hypotensive, analgesia if pain
2. Anticoagulation: start LMWH (enoxaparin) or fondaparinux as soon as PE suspected - continue for at least 5 days or until INR 2+ for at least 24hrs

Alternatives:

• consider systemic thrombolytic therapy (IV alteplase) for pts with PE and haemodynamic instability
• offer temporary IVC filter or surgical embolectomy for pts with PE who cannot have anticoagulation

Question 7

how should pts be followed 3 mths post-PE?

Answer 7

1. decide if continued anticoagulation

2. echo to check for RV failure/congestive HF