Cyanosis

Medicine > Cardiovascular

Differential Diagnosis Schema 🧠

Central Cyanosis

Congenital heart disease: Often presents in neonates or infants with cyanosis, failure to thrive, and signs of heart failure (e.g., Tetralogy of Fallot, transposition of the great arteries).
Respiratory failure: Causes include pneumonia, bronchiolitis, or severe asthma; look for associated tachypnoea, dyspnoea, and hypoxia.
Methemoglobinaemia: Cyanosis with chocolate-coloured blood, caused by drugs (e.g., dapsone, nitrates) or congenital enzyme deficiencies.
Severe hypoxia: Can result from advanced chronic obstructive pulmonary disease (COPD), pulmonary embolism, or severe pneumonia.
Cardiogenic shock: Cyanosis with hypotension, cold extremities, and raised jugular venous pressure, often due to myocardial infarction or heart failure.
Pulmonary embolism: Acute onset cyanosis, dyspnoea, pleuritic chest pain, and risk factors like recent surgery or immobility.
Severe anaemia: Cyanosis despite normal oxygen saturation due to decreased haemoglobin levels, often associated with pallor and fatigue.
Pneumothorax: Sudden onset of cyanosis with pleuritic chest pain, reduced breath sounds on the affected side, and hyper-resonance.

Peripheral Cyanosis

Heart failure: Peripheral cyanosis with signs of fluid overload (e.g., oedema, ascites), cold extremities, and reduced cardiac output.
Shock (e.g., septic, hypovolaemic): Cyanosis due to reduced perfusion, hypotension, tachycardia, and signs of poor end-organ perfusion.
Raynaud’s phenomenon: Episodic cyanosis of the fingers and toes in response to cold or stress, often with preceding pallor and subsequent redness.
Peripheral vascular disease: Chronic cyanosis, particularly in the lower limbs, with claudication, absent pulses, and possibly ulceration.
Venous obstruction (e.g., deep vein thrombosis): Cyanosis, swelling, and pain in the affected limb, often with a history of immobility or hypercoagulable state.
Hypothermia: Generalised cyanosis with cold extremities, shivering, and reduced core body temperature.
Arterial insufficiency: Cyanosis of the affected limb with pain, pallor, and absent pulses, often due to embolism or severe atherosclerosis.
Polycythaemia: Cyanosis due to increased red cell mass, often associated with ruddy complexion and splenomegaly, may be secondary to chronic hypoxia (e.g., COPD).

Key Points in History 🥼

Onset and Duration

Acute onset: Sudden cyanosis suggests acute causes such as pulmonary embolism, pneumothorax, or myocardial infarction.
Chronic onset: Gradual onset cyanosis may be due to chronic respiratory or cardiac conditions, such as COPD or heart failure.
Intermittent vs. persistent: Intermittent cyanosis can be seen in conditions like Raynaud’s phenomenon, while persistent cyanosis may suggest underlying chronic conditions.
Triggers: Identify any factors that trigger or worsen cyanosis, such as cold exposure (Raynaud’s), exertion (heart failure), or positional changes.

Associated Symptoms

Shortness of breath: Suggests a respiratory or cardiac cause, such as pulmonary embolism, pneumonia, or heart failure.
Chest pain: Pleuritic pain may suggest pulmonary embolism or pneumothorax, while central chest pain may indicate myocardial infarction.
Fever: May indicate an infectious cause, such as pneumonia or sepsis.
Syncope or dizziness: Suggests reduced cerebral perfusion, possibly due to severe hypoxia, heart failure, or arrhythmia.
Fatigue and weakness: Common in chronic hypoxia or anaemia.
Palpitations: May indicate arrhythmias, often associated with cardiogenic causes of cyanosis.
Leg pain or swelling: Suggests deep vein thrombosis or peripheral vascular disease.
Cough or haemoptysis: Suggests respiratory causes such as pneumonia, tuberculosis, or pulmonary embolism.

Background

Past medical history: Previous diagnoses of cardiac or respiratory conditions, such as congenital heart disease, COPD, or heart failure, can predispose to cyanosis.
Drug history: Medications like beta-blockers or amiodarone may exacerbate cyanosis, and ask about use of nitrates or dapsone, which can cause methemoglobinaemia.
Family history: History of congenital heart disease, respiratory conditions, or haematological disorders may increase suspicion of hereditary causes.
Social history: Smoking, alcohol use, and occupational exposures (e.g., asbestos) may contribute to respiratory or cardiac causes.
Travel history: Recent travel to areas with endemic tuberculosis or exposure to high altitudes, which may cause hypoxia.
Lifestyle factors: Sedentary lifestyle or lack of exercise may predispose to venous thromboembolism or other vascular conditions.
Birth history: In infants, prenatal and birth history is crucial to identify congenital causes, such as cyanotic heart defects.

Possible Investigations 🌡️

Bedside Tests

Pulse oximetry: First-line assessment to measure oxygen saturation; low readings suggest hypoxia.
Arterial blood gas (ABG): To measure PaO2, PaCO2, and pH; assess for hypoxia, hypercapnia, and acidosis.
Electrocardiogram (ECG): To assess for arrhythmias, ischaemia, or signs of right heart strain (e.g., in pulmonary embolism).
Sputum culture: If infection is suspected, particularly in cases of pneumonia or tuberculosis.
Capillary refill time: To assess peripheral perfusion, particularly in shock or heart failure.
Observations: Regular monitoring of vital signs including respiratory rate, heart rate, blood pressure, and temperature.
Six-minute walk test: To assess functional capacity and oxygen desaturation on exertion in chronic lung diseases.
Carbon monoxide (CO) levels: In cases of suspected CO poisoning, particularly in those with central cyanosis and normal PaO2 on ABG.
Methemoglobin levels: If methemoglobinaemia is suspected, particularly with cyanosis unresponsive to oxygen therapy.

Blood Tests

Full blood count (FBC): To assess for anaemia, polycythaemia, and infection.
Urea and electrolytes (U&E): To assess renal function and electrolyte balance, particularly in patients with heart failure or shock.
D-dimer: To assess for thromboembolic disease, particularly in suspected pulmonary embolism.
Brain natriuretic peptide (BNP): Elevated in heart failure, useful in differentiating cardiac from pulmonary causes of cyanosis.
C-reactive protein (CRP): To assess for infection or inflammation, particularly in pneumonia or other inflammatory conditions.
Liver function tests (LFTs): To assess for hepatic causes of cyanosis, such as cirrhosis with hepatopulmonary syndrome.
Thyroid function tests: To assess for hypothyroidism, which can exacerbate cyanosis, particularly in heart failure.
Blood cultures: If sepsis is suspected, particularly in cases with fever and signs of systemic infection.
Coagulation profile: To assess for coagulopathy, particularly in cases of suspected deep vein thrombosis or pulmonary embolism.
Toxicology screen: If drug overdose or poisoning is suspected, particularly in cases of methemoglobinaemia or carbon monoxide poisoning.
Lactate levels: Elevated in shock, sepsis, and severe hypoxia, useful in assessing severity and prognosis.

Imaging and Special Tests

Chest X-ray: To assess for pneumonia, pneumothorax, pleural effusion, or cardiomegaly.
CT pulmonary angiography: To confirm pulmonary embolism, particularly in patients with acute dyspnoea and pleuritic chest pain.
Echocardiography: To assess cardiac function, particularly in suspected heart failure, congenital heart disease, or valvular disease.
Ventilation-perfusion (V/Q) scan: Alternative to CT pulmonary angiography in patients with suspected pulmonary embolism and contraindications to CT.
Ultrasound of the lower limbs: To assess for deep vein thrombosis in patients with leg swelling and suspected pulmonary embolism.
MRI brain: To assess for neurological causes of cyanosis, such as stroke or hypoxic-ischaemic injury, particularly in neonates or infants.
Pulmonary function tests: To assess for obstructive or restrictive lung disease in chronic cyanosis.
Right heart catheterisation: To measure pulmonary artery pressures in suspected pulmonary hypertension or right heart failure.
Cardiac MRI: To provide detailed imaging of the heart in congenital heart disease or complex cardiac conditions.
EEG (electroencephalogram): To assess for seizure activity or encephalopathy in patients with unexplained cyanosis and altered consciousness.

😃 More:

📖 Learning notes: 247

🏥 Stations available: 207

🧠 Qbank questions: 2255

😃 More:

Pricing:

Cyanosis

Differential Diagnosis Schema 🧠

Key Points in History 🥼

Possible Investigations 🌡️

No comments yet 😉

Leave a Reply Cancel reply

Cardiovascular