Pulmonary Embolism Flashcards
What is a pulmonary embolism?
Life-threatening condition resulting from dislodged thrombi occluding the pulmonary vasculature.
What is the aetiology of a pulmonary embolism?
- Thrombus formation within deep vein (pelvis/lower extremities) from blood stasis or hypercoagulability.
- Embolises to right heart and lungs. Medium-sized embolus occludes segmental artery.
- This causes a segment of lung being ventilated and not perfused (V/Q mismatch).
What is the difference between non-massive, massive and recurrent small pulmonary embolisms?
- Non-massive - medium sized embolus, segmental pulmonary artery, segment of lung ventilated, not perfused.
- Massive - massive embolus occludes proximal pulmonary artery/pulmonary artery bifurcation, blood cannot enter lung, sudden pulmonary hypertension, acute right heart failure.
- Recurrent small - multiple small emboli occlude arterioles, gradual development of pulmonary hypertension.
What is the inpatient primary prevention for pulmonary embolism?
- Early mobilisation post-op
- Mechanical intervention such as anti-embolic stockings
- Post-op prophylaxis - LMWH, fondaparinux and in cancer patients with low bleed risk.
- Avoid COCP in high risk individuals pre-surgery.
- Encourage use of compression stockings during long distance travel.
What is this a presentation of?
Acute dyspnoea, pleuritic chest pain, cough, haemoptysis, syncope, pyrexia, cyanosis, tachypnoea, tachycardia, hypotension (late).
Pulmonary embolism
What are the risk factors for developing a pulmonary embolism?
- Lower limb surgery
- Immobilisation
- Pregnancy/immediate post-partum
- Active malignancy
- DVT
How is someone with a suspected pulmonary embolism initially managed?
Oxygen, ECG, IV access, bloods, CXR
How do you risk stratify a suspected pulmonary embolism?
Wells score:
1. Clinical signs and symptoms of DVT (3)
2. HR >100 (1.5)
3. Immobilisation >3 days/surgery in previous 4 weeks (1.5)
4. Haemoptysis (1)
5. Previously diagnosed DVT/PE (1.5)
6. Malignancy (active treatment or stopped in the last 6 months) (1)
7. Alternative diagnosis less likely than PE (3)
>4 = likely, 4 or under = unlikely
What might a CXR show in a patient with a pulmonary embolism?
Often normal, may show small pleural effusion, wedge shaped infarction, atelectasis.
What might an ABG show in a patient with a pulmonary embolism?
Low PaO2 and PaCO2 due to hyperventilation
What might an ECG show in a patient with a pulmonary embolism?
Commonly normal/sinus tachycardia, may be deep S waves in I and deep Q waves in III and inverted T waves in III (S1, Q3, T3).
What blood test is used in patients with a low probability of pulmonary embolism?
D-dimer - low specificity, if negative then can be confidently ruled out, but also raised in MI/stroke/trauma/pregnancy/post-op.
What is the management for a pulmonary embolism in a haemodynamically unstable patient?
- Thrombolyse immediately using alteplase 10mg IV over 1 min then 90mg IV over 2 hours.
- Also use LMWH (dalteparin, enoxaparin)
What is the management for a pulmonary embolism in a haemodynamically stable patient?
- Calculate Wells score
- If high probability then CTPA with interim anticoagulation: if +ve offer treatment, if -ve then consider DVT.
- If low probability then d-dimer with interim anticoagulation: if +ve then CTPA and as above, if -ve consider different diagnosis.
What is the treatment for pulmonary embolism?
- High flow oxygen if hypoxic
- Analgesia, anti-emetic and IV access
- Loading dose of rivaroxaban (15mg BD) while awaiting confirmation
- If low BP, 500ml IV fluid bolus.
- If persistent low BP, consider vasopressors.
