Pulmonary Conditions

Pulmonary Embolus

This is an embolus in the pulmonary circulation, which can impair gas transfer.

The most common source is from a deep vein thrombosis (DVT) in the leg.

Small emboli are usually clinically silent as the lung has a dual blood supply.

Large emboli can give rise to pulmonary infarction causing a myriad of symptoms

Risk factors

Immobility – especially abdominal or hip/knee surgery, bed rest, long haul flights

Thrombophilia – these include blood disorders, e.g., antiphospholipid syndrome, factor V Leiden (the most common inherited thrombophilia) and malignancy

Oestrogen – from the contraceptive pill, hormone replacement therapy, pregnancy

Symptoms

Pleuritic chest pain, shortness of breath and haemoptysis

Tachycardia, tachypnoea, oxygen desaturation

Pleural rub (which disappears when you hold your breath)

Pea-body sign, a clinical sign that involves calf pain upon dorsiflexion of the foot

Key tests

Pulse oximeter may show low SpO2

ABG shows hypoxia, low PaO2 (suggestive of show type I respiratory failure)

CXR – this is usually normal and performed to rule out other pathologies

ECG – pathognomonic pattern is S1-Q3-T3. Deep S waves in lead I, pathological Q waves and inverted T waves in lead III

CTPA – this is gold standard and shows vascular filling defect in lung.

V/Q lung scan – shows mismatch between ventilation and perfusion. It is used when CTPA is unsuitable, e.g., due to poor kidney function or in pregnancy/young females

Diagnosis

The diagnostic pathway involves calculating the two-level Well’s score.

If score is 4 or more, it is suggested to go for immediate CTPA

If score is less than 4, request a D-dimer. If this is raised, then get CTPA

If CTPA is delayed, give the treatment dose of anticoagulation until scan is performed

Management

If hemodynamically unstable, patients require thrombolysis (e.g., alteplase)

If haemodynamically stable, therapeutic anticoagulation for 3–6 months

Pulmonary hypertension

This is a condition which is caused by a resting mean pulmonary artery pressure >25mmHg.

The main problem is that raised pulmonary pressure caused increased stress on the right side of the heart and can lead to right sided heart failure, a complication known as cor pulmonale

Primary hypertension occurs due to atherosclerosis of pulmonary trunk, smooth muscle hypertrophy and fibrosis, leading to the development of plexiform lesions.

Endothelin-1 is a potent pulmonary vasoconstrictor produced in increased amounts in pulmonary hypertension. It also induces the proliferation of pulmonary vascular smooth muscle.

Causes

Primary

This is typically seen in young adult females, aged 30-50 years

Due to an idiopathic cause, but there are some autosomal dominant forms due to inactivation mutations of BMPR2 leading to increased proliferation of vascular smooth muscle

Secondary

Due to hypoxemia (e.g. COPD)/ increased circulating volume (heart disease) or PE

Symptoms

Leads to progressive exertional shortness of breath

Chest pain

Syncope

Eventual Cor pulmonale – cardiac complication of pulmonary hypertension that involves right ventricular failure and hence gives jugular venous distension, oedema and hepatomegaly

Management

Acute vasodilator testing is used to decide on the appropriate management strategy:

If positive response to vasodilator testing, Give oral Ca2+ channel blockers

If negative response options include PDE 5 inhibitor (Sildenafil), endothelin antagonist (Bosentan) or prostacyclin analogues (Iloprost)