Pulmonary Embolism Flashcards
What are the risk factors for venous thromboembolism in hospital inpatients? (16 in total)
- Age >60
- One or more significant medical comorbidities (e.g. heart disease, respiratory failure, acute infection)
- Obesity (BMI >30 kg/m2)
- Major abdominal/pelvic surgery
- Active cancer or cancer treatment
- Pregnancy
- Use of oestrogen-containing OCP/HRT
- Significant immobility
- Varicose veins with phlebitis
- Diabetic coma
- Personal or 1st degree relative history of VTE
- Thrombophilia
- Inflammatory bowel disease
- Nephrotic syndrome
- Critical care admission
- Dehydration
In which veins do emboli usually arise from?
- Pelvic or abdominal veins
- Most clinically relevant PEs - Femoral DVT
- Axillary DVT
Clinical DVT not commonly observed. Detailed Ix of iliofemoral or pelvic veins reveals thrombosis in >50% cases
True or false: in PE, the lung tissue is well perfused but not ventilated, resulting in impaired gas exchange.
False - the lung tissue is well ventilated but not perfused, producing an intrapulmonary deadspace.
After some hours: reduced surfactant production, alveolar collapse and increased hypoxaemia.
True or false: a small embolus impacting a terminal pulmonary vessel may be clinically silent.
True - oxygen continues to be supplied by the bronchial circulation.
What are the main intrinsic risk factors for clot formation?
- Sluggish blood flow
- Local injury or compression
- Hyercoagulable state
Emboli can also occur from:
- Tumour
- Fat (e.g. long bone #)
- Amniotic fluid
- Foreign material during IVDU
How does PE typically present?
- Small/medium
- PC: sudden onset dyspnoea, pleuritic chest pain and haemoptysis (if infarcted)
- O/E: tachypnoeic, pleural rub
- Exudative pleural effusion can develop - Massive
- Medical emergency
- PC: severe central chest pain, pale & sweaty
- O/E: marked tachypnoea and tachycardia, shocked, central cyanosis, raised JVP, RV heave, loud S2 and gallop rhythm (acute right heart failure)
Multiple recurrent
- Symptoms & signs of pulmonary hypertension, developing over weeks to months
What is the first-step in management of suspected PE?
Determine pre-test clinical probability (revised Geneva score)
Name and outline the clinical pre-test probability score for prediction of PE
Revised Geneva Score:
Risk factors
- Age >65: +1
- Previous DVT or PE: +3
- Surgery or fracture within 1 month: +2
- Active malignancy: +2
Symptoms
- Unilateral leg pain: +3
- Haemoptysis: +2
Clinical signs
- HR 75-94: +3
- HR 95+: +5
- Pain on deep leg palpation and unilateral oedema: +4
Clinical probability
- Low: 0-3
- Intermediate: 4-10
- High: 11+
About 8% of patients with a low score will have a PE
A 68 year old patient presents with dyspnoea and pleuritic chest pain. He had a hernia repair 2 weeks ago. On examination he is slightly tachycardic (85 bpm) and tachypnoeic. What is his pre-test probability of PE? How would you proceed?
Age >65: 1
Recent surgery: +2
HR 75-94: +3
Total score = 6 (intermediate)
Start LMWH and send for CTPA. If PE present, start warfarin. If CTPA inconclusive, repeat or Doppler US of legs or V/Q scan.
A 53 year old female presents with dyspneoa and haemoptysis. HR 74, BP 130/85. What is her pre-test probability of PE? Her D-dimer is negative. How would you proceed?
Haemoptysis: +2
Total score = 2 (low)
D-dimer -ve. Seek alternative cause for symptoms (CXR, ECG).
A 65 year old patient with presents with severe central chest pain and breathlessness. He was Dx with DVT 6 months ago. SaO2 88, BP 100/53, HR 100. Examination reveals central cyanosis, a raised JVP, RV heave, loud S2 and gallop rhythm. How would you manage this patient?
This patient has acute right heart failure indicating a massive PE: this is a medical emergency.
- High flow oxygen
- Hypoxaemic - Thrombolysis and CTPA
- For massive embolism with persistent hypotension
- Or bedside echo if too unstable - Analgesia
- Morphine 5-10 mg IV
- Relieve pain and anxiety - LMWH and oral warfarin
- Prevent further thrombi - IV fluids
- Raise filling pressure for moderate/severe embolism
What investigations are indicated for suspected/confirmed PE?
Geneva score is used prior to investigation to help decide on most appropriate 1st-line Dx test.
- CXR
- Decreased vascular markings
- Atelectasis
- Raised hemidiaphragm (loss of lung volume)
- Wedge-shaped opacity adjacent to pleural edge (late feature)
- Enlarged pulmonary artery
- Pleural effusion - ECG
- Sinus tachycardia
- New onset AF
- Acute right HF: tall peaked P waves (lead II), RAD, RBBB - ABG
- Hypoxaemia and hypercapnia with massive emboli - D-dimer
- In patients with low pre-test score
- Also elevated in cancer, pregnancy, post-operatively - CTPA
- Highly sensitive for large proximal pulmonary emboli
- Segmental emboli may be missed
- Advantage over V/Q: also detects alternative pathology - V/Q scan
- Patients with coexistent chronic lung disease may need further imaging - US
- Detects clots in pelvic or iliofemoral veins - MRI
- If CT is contraindicated - Echocardiogram
- Diagnostic in massive PE
- Performed at bedside
- Demonstrates proximal thrombus and RV dilatation
What is the pathology behind a massive PE?
A massive embolism obstructs the right ventricular outflow tract causing a sudden increase in pulmonary vascular resistance, leading to acute right heart failure.
Is thrombolysis indicated in the management of PE?
Yes - but only in acute massive embolism if persistant arterial hypotension
Is surgery indicated in the management of PE?
If thrombolysis is contraindicated or ineffective (in massive PE with hypotension), surgical embolectomy may be undertaken
