Cyanosis in Pediatrics

(OP Ghai Essential Pediatrics - Reference Framework, 9th Ed.)

Definition

• Visible when reduced Hb > 5 g/dL in the capillaries (absolute amount, not percentage)
• Therefore: an anemic child may not appear cyanotic despite severe hypoxia (Hb too low to reach 5 g/dL reduced)
• Conversely: a polycythemic child may appear cyanotic at a higher SaO2

Classification of Cyanosis

1. Central Cyanosis

• Involves mucous membranes, tongue, lips, trunk
• Due to decreased arterial oxygen saturation (SaO2 <85%)
• Always pathological

• Cyanotic congenital heart disease (right-to-left shunts):
  • Tetralogy of Fallot (TOF) - most common beyond neonatal period
  • Transposition of Great Arteries (TGA) - most common in neonates
  • Tricuspid Atresia (TA)
  • Total Anomalous Pulmonary Venous Return (TAPVR)
  • Truncus Arteriosus
  • Hypoplastic Left Heart Syndrome (HLHS)
  • Pulmonary Atresia
  • Ebstein Anomaly
  • Eisenmenger Syndrome (L→R shunt reversal due to pulmonary hypertension)

• Respiratory Distress Syndrome (RDS) / HMD
• Meconium Aspiration Syndrome (MAS)
• Pneumonia
• Congenital Diaphragmatic Hernia (CDH)
• Pulmonary hypoplasia
• Persistent Pulmonary Hypertension of Newborn (PPHN)
• Pneumothorax
• Severe airway obstruction: Choanal atresia, Pierre Robin sequence, laryngeal web

• Intraventricular hemorrhage
• Birth asphyxia / HIE
• Central hypoventilation
• Severe hypoglycemia
• Sepsis/shock
• Polycythemia

• Methemoglobinemia (Hb cannot carry O2; blood appears chocolate-brown)

2. Peripheral Cyanosis (Acrocyanosis)

• Cyanosis of extremities only (hands, feet, perioral area)
• Mucous membranes and tongue remain pink - normal SaO2
• Due to increased O2 extraction from blood in periphery (vasoconstriction)
• Normal in first 48-72 hours of life (vasomotor instability)
• Pathological causes: Low cardiac output, cold exposure, polycythemia, congestive heart failure

3. Differential Cyanosis

• Pre-ductal vs post-ductal pulse oximetry is used to detect differential cyanosis (right hand = preductal; lower limb = postductal)

Pathophysiology of Cyanosis

• SpO2 drops below ~85% in normal Hb
• Higher threshold in polycythemia (cyanosis at higher SpO2)
• Lower threshold in severe anemia (may not appear cyanotic despite severe hypoxia)

1. Decreased SaO2 - V/Q mismatch, hypoventilation, diffusion defect (pulmonary)
2. R→L shunt - Deoxygenated blood bypasses lungs (cardiac)
3. Abnormal Hb - Methemoglobin, sulfhemoglobin
4. Increased O2 extraction peripherally - slow circulation (peripheral cyanosis)

Clinical Approach to Cyanotic Child

Step 1: Confirm Cyanosis

• Examine tongue and oral mucosa (best site for central cyanosis)
• Distinguish from pseudo-cyanosis (silver/lead poisoning, tattoo)
• Pulse oximetry

Step 2: Central vs Peripheral

• Tongue involved → Central
• Tongue pink → Peripheral (acrocyanosis)

Step 3: Cardiac vs Non-Cardiac (The Hyperoxia Test)

• Child breathes 100% O2 via oxygen hood for 10 minutes
• Preductal ABG (right radial artery) or pulse oximetry measured before and after

• Limitation: PPHN may also fail to respond; echocardiography is gold standard

Step 4: Respiratory pattern clues

Investigations

Chest X-Ray Clues in Cyanotic CHD

ECG Clues

Cyanotic Spells (Hypercyanotic/Tet Spells) - TOF Specific

• Occur in infants 2-4 months of age, usually after crying, feeding, or waking
• Due to sudden increase in RVOT obstruction → increased R→L shunt → severe hypoxia

• Sudden increase in cyanosis
• Hyperpnea (deep, rapid breathing)
• Irritability → limpness → syncope
• Disappearance or softening of pulmonary ejection murmur
• Metabolic acidosis

1. Knee-chest position (increases systemic vascular resistance, reduces R→L shunt)
2. O2 supplementation
3. Morphine 0.1-0.2 mg/kg SC/IV (reduces hyperpnea, calms child, relaxes RVOT)
4. IV fluids (increases preload)
5. Propranolol 0.1 mg/kg IV (slow infusion - relaxes RVOT spasm)
6. Sodium bicarbonate to correct acidosis
7. Phenylephrine (increases SVR)
8. Long-term oral propranolol (0.5-1 mg/kg/day TDS) until surgical repair

Management of Cyanosis - General Principles

• Airway, Breathing, Circulation (ABC)
• Supplemental O2 (note: O2 may harm duct-dependent lesions - use cautiously)
• IV access + glucose monitoring
• Empiric antibiotics if sepsis suspected
• Prostaglandin E1 (PGE1) - if duct-dependent cardiac lesion suspected (0.05-0.1 mcg/kg/min) - maintains ductal patency

• Cardiac causes → surgical/interventional cardiology (BT shunt, balloon septostomy, corrective surgery)
• Pulmonary causes → surfactant (RDS), ventilation support
• PPHN → iNO (inhaled nitric oxide), HFOV
• Methemoglobinemia → Methylene blue 1-2 mg/kg IV

Polycythemia and Cyanosis

• Polycythemia (venous Hb >22 g/dL, Hct >65%) can cause central cyanosis
• Causes: IUGR, IDM, twin-to-twin transfusion, delayed cord clamping
• Treated with partial exchange transfusion if symptomatic

Methemoglobinemia

• Hb unable to carry O2 (Fe2+ oxidized to Fe3+)
• Causes: nitrate-contaminated water, topical anesthetics (benzocaine), dapsone, naphthalene
• Blood appears chocolate brown
• SpO2 falsely reads ~85% regardless of severity
• PaO2 normal on ABG (dissolved O2 unaffected)
• Treat with Methylene blue 1-2 mg/kg IV over 5 min

Key Points for Exam (OP Ghai Focus)