Cyanosis in newborns: Best article 2025

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Definition

• Cyanosis: Bluish discoloration of the skin and mucous membranes caused by increased deoxygenated hemoglobin (>5 g/dL) in capillary blood.

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Classification of Cyanosis

1. Peripheral (Acrocyanosis)

• Bluish discoloration of extremities, often seen in healthy neonates due to vasomotor instability or cold stress.
• Not associated with hypoxemia.
• Usually resolves with warming.

1. Central

• Bluish discoloration of the tongue, mucous membranes, and trunk, indicating systemic hypoxemia (arterial oxygen saturation <85%).
• Requires urgent evaluation to identify underlying pathology.

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Causes of Cyanosis in Newborns

1. Respiratory Causes

• Airway obstruction: Choanal atresia, laryngomalacia.
• Lung disease: Respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), meconium aspiration syndrome (MAS), or pneumonia.
• Hypoventilation: CNS depression, maternal sedation.

1. Cardiac Causes

• Cyanotic congenital heart diseases (CHDs): The “5 Ts”
  • Tetralogy of Fallot (TOF)
  • Transposition of the great arteries (TGA)
  • Tricuspid atresia
  • Total anomalous pulmonary venous connection (TAPVC)
  • Truncus arteriosus
• Persistent pulmonary hypertension of the newborn (PPHN).

1. Hematological Causes

• Polycythemia increases blood viscosity, causing sluggish flow and cyanosis.

1. Metabolic/Other Causes

• Hypoglycemia.
• Hypothermia.
• Sepsis.
• Methemoglobinemia or sulfhemoglobinemia.

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Evaluation of Neonatal Cyanosis

1. History

• Prenatal factors: Maternal infections, drug use, gestational diabetes.
• Perinatal history: Mode of delivery, APGAR scores, meconium-stained liquor.

1. Physical Examination

• Central vs peripheral cyanosis.
• Assess respiratory effort, heart sounds, murmurs, capillary refill time.

1. Diagnostic Tests

• Pulse oximetry: Differentiates hypoxemia from other causes.
• Hyperoxia test: Administer 100% oxygen and assess PaO₂ levels.
  • PaO₂ >150 mmHg: Likely respiratory cause.
  • PaO₂ : Cardiac cause (CHD).
• Arterial blood gas (ABG): pH, PaO₂, PaCO₂.
• Chest X-ray: Evaluates lung pathology and cardiac size.
• Echocardiography: Definitive test for CHD.
• Complete blood count (CBC), glucose, blood culture (if infection suspected).

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Management Principles

1. Initial Stabilization

• Secure airway, ensure adequate ventilation and oxygenation.
• Administer supplemental oxygen (high-flow or CPAP).
• Correct metabolic abnormalities (e.g., hypoglycemia, acidosis).

1. Definitive Treatment

• Respiratory causes: Treat underlying lung pathology (e.g., surfactant for RDS, antibiotics for pneumonia).
• Cardiac causes: Prostaglandin E1 infusion to maintain ductal patency in duct-dependent CHD.
• PPHN: Inhaled nitric oxide (iNO), sildenafil, or ECMO for refractory cases.
• Methemoglobinemia: Methylene blue (1-2 mg/kg IV).

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Prognosis

• Depends on the underlying etiology. Early diagnosis and intervention significantly improve outcomes. Cyanotic CHDs often require surgical correction or catheter-based interventions.

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