pulmonary_embolism
Pulmonary Embolism (PE)
Causes
although the terms do not help with decision making around duration of treatment 2 terms are often used:- Provoked PE - associated with a recent (≤3 months) and transient major risk factor, such as significant immobility, surgery, trauma, pregnancy or puerperium, or use of hormonal therapy (combined contraceptive pill or hormone replacement therapy)
- Unprovoked PE - occurs in the absence of a recent (≤3 months) major clinical risk factor in a person who is not using hormonal therapy.
Clinical
- may be asymptomatic
- SOB, cough +/- haemotypsis
- pleuritic chest pain
- associated leg pain/swelling, signs of DVT
- massive PE - central cyanosis, altered/LOC, collapse or shock
- tachypnoea, tachycardia, hypotension
- elevated JVP, parasternal heave, loud P2
- Fever is common in PE and can occur in ≥25% patients
- clinical categorisation to direct Mx:
- massive (high risk)- shock, persistent brady or asystole
- sub-massive (intermediate risk) - evidence of RV dysfunction but no signs of shock
- low risk - no evidence of RV dysfunction or shock
Investigations
- bloods: FBC, U&E's, clotting, d-Dimer
- ECG - often normal
- sinus tachycardia
- signs of R heart strain -SI, QIII, TIII (probably <10%), non-specific ST changes or TWI in anterior leads, right axis deviation, S wave (I and aVL) > 1.5mm, Q in III and aVF, P pulmonale & RBBB
- ABG - hypoxia. Repeat after exercising may enhance diagnostic workup. Resp alkalosis. Metabolic acidosis if shock
- CXR - only to rule out other pathology
- CTPA - may not pick up smaller emboli
If no obvious cause, risk factors Ix should follow:
- Antithrombin III deficiency
- Protein C or protein S deficiency
- Lupus anticoagulant
- Homocystinuria
- Occult neoplasm
- Connective tissue disorders
Management
- Low molecular weight heparin (LMWH)
- Fondaparinux.
- Unfractionated heparin.
- Oral anticoagulants: Warfarin, apixaban, or rivaroxaban.
- LMWH followed by an oral anticoagulant (dabigatran or edoxaban)
- Thrombolysis - only for massive. Debate continues about their place in sub-massive
- plasminogen activators - fibrin specific rt-PA or non selective agents - streptokinase, urokinase
- IVC filters and embolectomy
simplified PESI score >>
Simplified PESI score
Age
Hx of Cancer?
Hx of cardiopulmonary disease
HR
sBP
O2 sat%
Low Risk=0, High Risk ≥1
WELLS score (PE)>>
WELLS score (PE)
Clinical Signs, Symptoms of DVT
Alternative Dx is less likely than PE?
HR›100?
immobilisation ≥3 consecutive days or surgery in previous 4/52?
previous objectively diagnosed PE, DVT
haemoptysis?
malignancy (on Rx, or in last 6/12 or palliative)?
Low Risk: 0-1
Moderate risk: 2-6
High Risk: ›6
Author: Dr Dylan Jenkins. Nov '23 refs