Rawan Alsulmi

PULMONARY EMBOLISM

• Relevant anatomy

• Definition

• Risk Factors

• Pathology

• Clinical features

• Investigation

• Deferential Diagnosis

• Management

CONTENT

The lungs are supplied with deoxygenated blood by the paired pulmonary arteries.

Once the blood has received oxygenation, it leaves the lungs via four pulmonary veins .

RELEVANT ANATOMY

WHAT IS PE?A pulmonary embolism refers to the obstruction of a pulmonary artery.

The most common emboli are:

Thrombus – responsible for the majority of cases and usually arises from ilio-femoral veins or pelvic veins.

Fat – following a bone fracture or orthopaedic surgery.

Air – following cannulation in the neck.

Amniotic fluid.

RISK FACTORS:“VIRCHOW’S TRIAD”

A massive embolism obstructs the right ventricular outflow tract and therefore suddenly increases pulmonary vascular resistance, causing acute right heart failure. A small embolus impacts in a terminal, peripheral pulmonary vessel and may be clinically silent unless it causes pulmonary infarction. Lung tissue is ventilated but not perfused, resulting in impaired gas exchange.

PATHOLOGY

CLINICAL FEATURES • Dyspnea

• Tachypnea

• Pleuritic chest pain

• Fever

• Unilaterally swollen and painful posterior lower extremity,

• Cough, Hemoptysis

• Patient prefers to lie flat, dyspnoea improves due to increased venous return and right heart loading.

INVESTIGATIONS

Lab:- ABGLow PaO2, low or high PaCO2, and a metabolic acidosis.

- D-dimers Sensitivity = 95-98% A normal value probably excludes a pulmonary embolus

INVESTIGATIONS Imaging :

1- X-ray:

• Fewer vascular markings (pulmonary oligaemia)

• Hampton’s hump sign

Wedge-shaped infarct

• Westmark’s sign

Hyperlucency in the lung region supplied by the affected artery

CONT.…2- ECG: Sinus tachycardia S1Q3T3—S wave in lead I, Q wave in lead III, and inverted T wave in lead III , tachycardia, right axis deviation, right bundle branch block, P pulmonale. 3- Echocardiogram: may reveal evidence of pulmonary hypertension and acute right ventricular strain.

CONT..

4- Ventilation-perfusion scan: Sensitivity = 98%; specificity = 40%

5- Pulmonary angiography:

is the Diagnostic test of choice

DDXCondition Differentiating signs/symptoms

MI Retrosternal pressure radiating to the jaw, arm, or neck.Risk factors include long-standing hypertension, diabetes, or hypercholesterolaemia.

Pneumonia Cough, purulent sputum.Fever above 39.0°C generally higher than in PE.

Pneumothorax History of recent trauma to the chest.Decreased breath sounds unilaterally Hyperresonance on percussion of affected side.Deviation of the trachea away from the affected lung.

CHF, acute exacerbation Orthopnoea, paroxysmal nocturnal dyspnoea,Increased bilateral lower extremity swelling.Diffuse crackles on pulmonary auscultation.Elevated jugular venous pressure.

Pericarditis Chest pain improves when sitting up and worsens when supine.

Tamponade, cardiac Beck's triad of hypotension, muffled heart sounds, and elevated jugular venous pressure

Panic disorder Sudden-onset anxiety, feeling faint, and palpitations.Recurrent, discrete period of intense fear/discomfort.

MANAGEMENT General management

• FIO2 0.6–1.0 to maintain SaO2 93–98%. • Lie patient flat to increase venous return. • Fluid challenge to optimize right heart filling. • Epinephrine infusion if circulation still compromised. • Mechanical ventilation may be needed. Gas

exchange may worsen due to loss of preferential shunting and decreases in cardiac output.

PULMONARY EMBOLISM IN PREGNANCY

Ultrasonography of the legs is the initial investigation. CTPA is required if ultrasound is normal Warfarin is teratogenic and confirmed PE is treated with LMWH.

REVERENCES Oxford critical care BMJ Kumar and Clark’s clinical medicine

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