Pulmonary Embolism Flashcards
What forms a Pulmonary Embolus?
- Emboli can also occur from:
- Tumour,
- Fat,
- Amniotic fluid
- Foreign material during IV drug misuse
- Most clots causing PE actually come from pelvic, abdominal thrombosis, axillary thrombosis, femoral DVT
How fatal are pulmonary emboli?
10% of clinical pulmonary emboli are fatal.
How do thrombi form?
Clots form as a result of combination:
- Sluggish blood flow
- Local injury or compression of vein
- Hypercoagulable state.
‘Virchow’s Triad’
What is the pathophysiology of massive Pulmonary Embolism?
Acute obstruction of right ventricular outflow tract resulting in sudden collapse
What are clinical features of Massive PE?
- Severe central chest pain (lack of coronary blood flow leading to cardiac ischaemia)
- Shock
- Pale and sweaty
- Syncope may result if cardiac output transiently but dramatically reduced and death may occur
What are examination findings of Massive PE?
- Tachypnoeic
- Tachycardic
- Hypotension
- Peripheral shutdown
- JVP raised with prominent a-wave.
- Right ventricular heave, gallop rhythm and widely split-second heart sound
What is the treatment for massive PE?
Thrombolyisis - IV Alteplase
What are clinical features of Chronic Recurrent Pulmonary Embolism?
- Dyspnoea
- Weakness
- Syncope on exertion
- Occasionally angina
What are examination findings of Chronic Recurrent Pulmonary Embolism?
- Right ventricular overload with right ventricular heave
- Loud pulmonary second sound
What are risk factors for Pulmonary Embolism?
- Surgery: abdominal/pelvic, Knee/Hip replacement, Post-operative Spell on ITU
- Obstetric: Late pregnancy, Caesarian Section
- Lower limb: Fracture, Varicose veins
- Malignancy
- Reduced Mobilitiy
- Previous proven VTE
What is the disease process of a PE?
- Lung tissue ventilated but not perfused producing intrapulmonary dead space and V/Q mismatch
- Alveolar collapse occurs due to lack of surfactant and exacerbates hypoxaemia
- Primary haemodynamic consequence is reduction in cross sectional area of pulmonary arterial bed.
- Leads to elevation of pulmonary arterial pressure and reduction in cardiac output
- Right ventricular ischaemia can occur as result
How is Right Ventricular Ischaemia detected?
- Troponin levels
- Creatine kinase levels
What can result from distal embolisation?
Pulmonary infarction
- Alveolar haemorrhage with haemoptysis
- Pleural inflammation
- Effusion
What are clinical features of Pulmonary Embolism?
- Sudden unexplained dyspnoea
- Pleuritic chest pain
- Haemoptysis
- Patient may have fever
What are examination findings of Pulmonary Embolism?
- Patient tachypnoeic with localised pleural rub and coarse crackles over area involved.
- Patient may have fever
What are investigations undertaken for Pulmonary Embolism?
- CT pulmonary angiography (definitive)
- Plasma D-dimer
- MRI
- Chest X-ray
- ECG
- Blood Gases
- Cardiac troponins and BNP
- Radionuclide ventilation/perfusion scanning (V/Q scan)
- Ultrasound scanning
- Echocardiography
What Well’s Score is required for CTPA?
- Used to accurately diagnose and exclude pulmonary embolism
- Wells Score over 5 means definite investigation
- MRI or V/Q scan is used if contraindicated
What does X-Ray show for a Pulmonary Embolism?
- Linear atelectasis or blunting of costophrenic angle.
- Occasionally, a wedge-shaped pulmonary infarct, abrupt cut-off of pulmonary artery or translucency of under-perfused distal zone is seen.
- Patient with massive PE may have pulmonary oligaemia. Those with recurrent pulmonary emboli may have enlarged pulmonary arterioles with oligaemic lung fields
What does X-Ray show on ECG?
- Sinus tachycardia
- Right atrial dilatation with tall peaked P waves in lead 2
- Right ventricular strain with right axis deviation and right bundle branch block
- T wave inversion in right pericardial leads
- The ‘classic’ ECG pattern with an S wave in lead I, and a Q wave and inverted T waves in lead III (S1, Q3, T3), is rare.
What does Blood Gases show in PE?
Type 1 Respiratory Failure Pattern: Significant pulmonary embolism will result in arterial hypoxemia with low arterial CO2 level so a
When is Echo indicated in Pulmonary Embolism?
- Assess for evidence of right ventricular dysfunction and may show thrombus
- In chronic recurrent PE, there may be right ventricular dilatation and hypertrophy with pulmonary arterial hypertension
What is the scoring system for Pulmonary Embolism?
Well’s Score Criteria
- Clinical signs and symptoms of DVT
- PE is #1 differential diagnosis OR equally likely
- Heart rate > 100
- Immobilization at least 3 days OR surgery in the previous 4 weeks -Previous, objectively diagnosed PE or DVT
- Haemoptysis
- Malignancy w/ treatment within 6 months or palliative
How are decisions made based on the Well’s Score?
Low risk if <2 points
- Consider D-dimer testing to rule out PE
- If D-dimer positive, then consider CTPA
- If D-dimer negative, consider stopping workup
Moderate risk if 2-6 points
- Consider High sensitivity D-dimer testing or CTPA
- If the D-dimer is negative, consider stopping workup
- If the D-dimer is positive, then CTPA
High Risk >6
- CTPA.
- D-dimer is not recommended
How is a Pulmonary Embolism managed?
- High flow oxygen (60-100%) given to all patient
- Initial anticoagulation with subcutaneous LMWH or fondaparinux or intravenous unfractionated heparin
- Intravenous fluids and even inotropic agents to improve the pump
- Thrombolysis therapy can improve pulmonary perfusion quicker than anticoagulation.
- Used in unstable patient and consider in stable patients with adverse features such as right ventricular dysfunction.
How are Pulmonary Emboli prevented?
- Warfarin
- DOAC, NOAC
- LMWH long term for cancer patient or pregnant women
What are some contradiction to Thrombolysis?
Absolute
- Haemorrhagic or Ischaemic stroke <6months
- CNS neoplasia
- Recent trauma or surger
- GI bleed <1month
- Bleeding disorder
- Aortic Dissection
Relative
- Warfarin
- Pregnancy
- Advanced Liver Disease
- Infective endocarditis
What are complications to Thrombolysis?
- Bleeding
- Hypotension
- Intracranial haemorrhage/Stroke
- Reperfusion arrhythmias
- Systemic embolization of thrombus
- Allergic Reaction
When does Plasma D-dimer increase?
- Elevated in patient with thromboembolism and negative test excludes diagnosis of pulmonary embolised.
- Elevated levels in patients with cancer, pregnant people and in hospitalized and elderly patients
