Everything about pulmonary embolism
What is pulmonary embolism ?
Occlusion of pulmonary vessels, most commonly by a thrombus that has travelled to the vascular system from another site.
what is pulmonary embolism is associated with ?
Pulmonary embolism is associated with risk factors for deep vein thrombosis for example such as surgical patients, immobility, obesity, oral contraceptive pills, heart failure and malignancy.
What is the epidemiology of pulmonary embolism ?
It is relatively common, especially in hospitalised patients they occurs in 10 % - 20% of those with a confirmed proximal deep vein thrombosis.
How does pulmonary embolism present ?
The presentation depends on the sizes and sites of the pulmonary embolus. In small pulmonary embolus it is asymptomatic or patient may present with low grade fever, fast heart rate and low saturation of oxygen and middle sizes embolus may present with sudden onset of shortness of breath, cough, coughing out blood, and sharp chest pain and present with increase respiratory rates, heart rates low oxygen saturation and sign of deep vein thrombosis.In large sizes of pulmonary embolus it may present with severe sharp central chest pain, shock, collapse, acute right failure or sudden death.Multiple small sizes of embolus may present with pulmonary hypertension and right sided heart failure.
What cause pulmonary embolism ?
Pulmonary embolism , 95% is caused by thrombus mostly originating from deep vein thrombosis of the lower limbs and rarely from right atrium in patient with atrial fibrillation.Other agents that can embolise to pulmonary vessels include amniotic fluid embolus, air embolus, fat embolus, tumour embolus and mycotic embolus from right sided endocarditis.
What is the pathology behind pulmonary embolism ?
In moderate case of pulmonary embolus occlusion of pulmonary artery braches causes pulmonary infarctio and a peripheral wedge - shaped haemorrhagic area. There may be a coexisting compromised collateral bronchial artery circulation.
In massive case of pulmonary embolism, the large embolus may wedge at the pulmonary artery bifurcation ( saddle embolus)
How to investigate pulmonary embolism ?
Bloods- Arterial blood gas, D-dimer test ( for cross- linked fibrin degradation products released into the circulation following fibrin breakdown; it is not very specific, especially if post surgical but negative results make pulmonary embolism very unlikely); thrombophilia screen if indicated prior to starting anticoagulation.
ECG - Often normal or more commonly shows tachycardia, right axis deviation, or right bundle branch block. Classical S1Q111T111 pattern is relatively uncommon.
Chest X ray - Often normal. May show a wedge shaped peripheral opacity, pulmonary oligaemia ( reduced vascular marking ), linear atelectasis, or a small plerual effusion. Mainly to exclude other differential diagnosis.
Ventilation perfusion scan.- Administration of IV 59M Tc macro -aggregated albumin and inhalation of 81 Krypton gas.This identifies any area of ventilation and perfusion mismatch that would indicates infarcted lung. May be difficult to interpret if there is coexisting lung disease.
Spiral CT pulmonary angiogram - Non invasive. Poor sensitivity for small emboli, but very sensitive for medium to large emboli. Investigation of choice if there is underlying lung disease.
Pulmonary angiography - Gold standard, but invasive. May be done prior to surgery for massive emboli.
Doppler ultrasound scan of lower limb - To examine venous thrombosis.
Echo cardiogram - May shows thrombus in heart or pulmonary artery.
How to manage pulmonary embolism ?
Primary prevention - Graduate pressure stockings (TEDs) and heparin prophylaxis in those at risk ( undergoing surgery ). Early mobilisation and adequate hydration post surgery.
If haemodynamically stable- Oxygen ; anticoagulation with heparin or low molecular weight heparin, changing to oral warfari therapy ( INR 2-3 ) for a minimum of 3 months. Analgesics for pain.
If haemodynamically unstable -resuscitate, give oxygen, Iv fluids resuscitations, thrombolysis with tPA has been used. Analgesia, followed by prevention of further thrombi.
Surgical or radiological - Embolectomy ( when thrombolysis is contraindicated). Inferior vena cava filters ( Greenfield filters) may be inserted when there are recurrent pulmonary emboli despite adequate anticoagulation or when anticoagulation is contraindicated.
What is the complication of pulmonary embolism ?
The complication includes death, pulmonary infarction, pulmonary hypertension, right heart failure ( cor pulmonale).
What is the prognosis for pulmonary embolism ?
The prognosis is 30% untreated mortality , but only 8% with treatment ( due to underlying emboli and recurrent emboli ). Patients have increase risk of future thromboembolic disease.
What is pulmonary embolism
ECG finding for pulmonary embolism
everything about pulmonary embolism
chest x ray for pulmoary embolism
CT scan ( white arrows show pulmonary embolus)
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