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Saturday, August 23, 2025

Blue or grey skin or lips (cyanosis)


Introduction

Cyanosis is defined as a bluish or grey discoloration of the skin, lips, nail beds, or mucous membranes due to increased amounts of deoxygenated hemoglobin (>5 g/dL) in capillary blood or abnormal hemoglobin variants.

It is an important clinical sign, often pointing to underlying cardiac, pulmonary, vascular, or hematological disease.

Types of Cyanosis

  1. Central Cyanosis

    • Generalized bluish discoloration (lips, tongue, mucous membranes, skin).

    • Indicates systemic hypoxemia (low oxygen in arterial blood).

    • Causes: lung disease, heart disease, high altitude.

  2. Peripheral Cyanosis

    • Affects extremities (fingers, toes, nail beds) but lips/tongue may remain pink.

    • Due to reduced blood flow or increased oxygen extraction.

    • Causes: cold exposure, shock, peripheral vascular disease, heart failure.

  3. Differential Cyanosis

    • Bluish lower limbs but not upper limbs (seen in patent ductus arteriosus with pulmonary hypertension).

  4. Pseudocyanosis

    • Bluish skin due to drugs (amiodarone, chloroquine) or metals (silver, gold), not due to hypoxemia.

Pathophysiology

  • Cyanosis develops when deoxygenated hemoglobin rises above 5 g/dL in capillary blood.

  • In anemia (low hemoglobin), cyanosis may be absent despite hypoxemia.

  • In polycythemia (high hemoglobin), cyanosis may appear even with mild hypoxemia.

  • Abnormal hemoglobin forms (methemoglobin, sulfhemoglobin) can also cause cyanosis.

Causes of Cyanosis

1. Respiratory Causes (Impaired Oxygenation)

  • Chronic obstructive pulmonary disease (COPD).

  • Asthma exacerbation.

  • Pneumonia.

  • Pulmonary embolism.

  • Interstitial lung disease.

  • Acute respiratory distress syndrome (ARDS).

  • High altitude.

2. Cardiac Causes (Right-to-Left Shunts / Poor Circulation)

  • Congenital heart disease (Tetralogy of Fallot, Eisenmenger syndrome).

  • Heart failure.

  • Myocardial infarction with low output.

  • Severe arrhythmias.

3. Hematological / Abnormal Hemoglobin

  • Methemoglobinemia (caused by drugs: dapsone, nitrates, benzocaine).

  • Sulfhemoglobinemia (rare, caused by sulfonamides).

  • Severe polycythemia.

4. Vascular / Peripheral

  • Shock, circulatory collapse.

  • Peripheral vascular disease.

  • Raynaud’s phenomenon.

  • Cold exposure.

5. Other / Rare

  • Sepsis.

  • Poisoning (carbon monoxide → “cherry red” but can mimic cyanosis).

Clinical Features

  • Skin/lips/mucous membranes: Blue, grey, or dusky color.

  • Central cyanosis: Lips, tongue, conjunctiva involved.

  • Peripheral cyanosis: Hands, feet, fingers, toes affected.

  • Associated symptoms depend on cause:

    • Shortness of breath, cough, wheezing (respiratory).

    • Chest pain, palpitations, edema (cardiac).

    • Cold extremities, pain, ulcers (vascular).

    • Headache, dizziness, confusion (methemoglobinemia, hypoxemia).

Diagnostic Approach

1. History

  • Onset: acute (PE, asthma, MI) vs chronic (COPD, heart disease).

  • Triggers: cold, exercise, altitude.

  • Medications: nitrates, dapsone, anesthetics.

  • Family history of congenital heart disease.

2. Examination

  • Distribution: central vs peripheral.

  • Vital signs: oxygen saturation, BP, HR, temperature.

  • Respiratory exam: wheeze, crackles.

  • Cardiac exam: murmurs, heart failure signs.

  • Extremities: pulses, skin temperature, capillary refill.

3. Investigations

  • Pulse oximetry: O₂ saturation <85% → cyanosis likely.

  • Arterial blood gas (ABG): PaO₂ <60 mmHg in hypoxemia.

  • Co-oximetry: Detects methemoglobin, carboxyhemoglobin.

  • Chest X-ray: Pneumonia, heart failure, effusion.

  • ECG & Echocardiography: Heart disease, shunts, pulmonary hypertension.

  • CT angiography: Pulmonary embolism.

  • Blood tests: CBC (polycythemia, anemia), renal/liver function.

Management and Treatment

Principle: Cyanosis is a sign → always treat underlying cause.

A. General Emergency Measures

  • Oxygen therapy: Nasal cannula (2–6 L/min) or mask.

  • Airway support if severe (intubation, mechanical ventilation).

B. Respiratory Causes

  • Asthma/COPD:

    • Oxygen, inhaled salbutamol 100–200 mcg every 4–6 h PRN.

    • Ipratropium 20 mcg inhaled every 6 h.

    • Prednisone 40 mg orally daily × 5–7 days.

  • Pneumonia:

    • Amoxicillin 1 g orally three times daily × 5–7 days.

    • Severe: Ceftriaxone 1–2 g IV daily + Azithromycin 500 mg IV/orally daily.

  • Pulmonary embolism:

    • Oxygen, anticoagulation.

    • Enoxaparin 1 mg/kg SC every 12 h.

    • Oral option: Apixaban 10 mg orally twice daily × 7 days, then 5 mg BID.

C. Cardiac Causes

  • Heart failure:

    • Furosemide 20–40 mg IV for fluid overload.

    • Enalapril 2.5–10 mg orally twice daily.

    • Carvedilol 3.125–25 mg orally twice daily.

  • Acute MI:

    • Oxygen, nitrates, aspirin 325 mg chewed, morphine, PCI if available.

  • Congenital cyanotic heart disease: Surgical correction or palliative shunt procedures.

D. Hematological / Toxic Causes

  • Methemoglobinemia:

    • Methylene blue 1–2 mg/kg IV over 5 min.

  • Sulfhemoglobinemia: Supportive, stop causative drug.

  • Polycythemia: Venesection (phlebotomy).

E. Peripheral / Vascular Causes

  • Shock: IV fluids, vasopressors (norepinephrine infusion).

  • Peripheral arterial disease: Antiplatelets (Aspirin 75–150 mg daily), statins, revascularization if severe.

  • Raynaud’s: Nifedipine 10–30 mg orally three times daily.

  • Cold exposure: Gradual warming, remove wet clothes.

Complications

  • Hypoxic brain injury.

  • Arrhythmias, cardiac arrest.

  • Cor pulmonale in chronic lung disease.

  • Secondary polycythemia (chronic hypoxemia).

  • Severe psychological distress.

Prognosis

  • Acute reversible causes (asthma, pneumonia, PE): Good if treated early.

  • Chronic diseases (COPD, cyanotic heart disease): Variable, depends on severity.

  • Toxic causes (methemoglobinemia): Rapid recovery if treated promptly.

Patient Education

  • Cyanosis is a warning sign → seek urgent medical help.

  • Stop smoking, avoid pollutants.

  • Manage chronic diseases (COPD, heart failure, diabetes).

  • Stay warm in cold environments to avoid peripheral cyanosis.

  • Patients with congenital heart disease require lifelong follow-up.




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