Therapeutic Hypothermia for Neonatal Encephalopathy
A male neonate born at 39 weeks had fetal bradycardia after placental abruption. Apgar scores are 2 and 4 at 1 and 5 minutes, and he needs positive pressure ventilation for 8 minutes. Cord arterial pH is 6.92. At 2 hours he is lethargic and hypotonic with an incomplete Moro reflex and a brief focal clonic seizure. Which intervention most reduces his risk of death or cerebral palsy?
- A.Elective mechanical ventilation
- B.Intravenous broad-spectrum antibiotics
- C.Intratracheal surfactant instillation
- D.Therapeutic whole-body cooling to 33.5 °CCorrect
Explanation
This infant meets criteria for moderate hypoxic-ischaemic encephalopathy, defined by a sentinel perinatal event, severe acidosis with a cord pH below 7.0 or base deficit of 16 mmol/L or more, depressed Apgar scores, and an abnormal neurological examination with seizures. Therapeutic hypothermia to a core temperature of 33 °C to 34 °C for 72 hours, started within 6 hours of birth in infants of at least 36 weeks gestation, is the only intervention proven in multiple randomized trials and meta-analysis of roughly 1500 infants to reduce the composite of death and major neurodevelopmental disability, including cerebral palsy, with a number needed to treat of about 7. Cooling works during the latent phase before secondary energy failure by lowering cerebral metabolic demand and suppressing excitotoxic glutamate release, free radical generation, inflammatory cytokines, and apoptotic pathways, which is why the 6-hour window is critical. Supportive care during cooling includes maintaining normoglycaemia, normocapnia, and normal blood pressure, and treating seizures, since hypocapnia and hyperoxia worsen injury. Antibiotics are given when sepsis cannot be excluded but do not by themselves modify hypoxic-ischaemic brain injury. Surfactant treats respiratory distress syndrome from surfactant deficiency, a disease of prematurity, and has no neuroprotective effect. Mechanical ventilation supports gas exchange and is often needed during cooling but is not itself neuroprotective. Cerebral palsy is a non-progressive disorder of movement and posture resulting from injury to the developing brain.
Why each option
- A.
- Ventilation supports gas exchange and is often required during cooling but confers no independent neuroprotection.
- B.
- Antibiotics treat suspected sepsis but do not modify hypoxic-ischaemic brain injury.
- C.
- Surfactant addresses respiratory distress syndrome of prematurity and has no neuroprotective role.
- D.
- Correct. Therapeutic hypothermia started within 6 hours reduces death and disability in moderate to severe hypoxic-ischaemic encephalopathy.
Reference: Cochrane Review, Cooling for newborns with hypoxic ischaemic encephalopathy, 2013; Nelson Textbook of Pediatrics, 22nd ed., 2024
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