What is the treatment for a newborn baby with Hypoxic-Ischemic Encephalopathy (HIE)?

Treatment of Neonatal Hypoxic-Ischemic Encephalopathy (HIE)

Therapeutic hypothermia is the standard of care and must be initiated within 6 hours of birth for term or near-term infants (≥36 weeks gestation) with moderate-to-severe HIE, as it reduces death or major neurodevelopmental disability by 22-33%. 1, 2

Patient Selection Criteria

Infants must meet ALL of the following criteria to qualify for therapeutic hypothermia 1, 3:

• Gestational age ≥36-37 weeks 1, 3
• Evidence of perinatal asphyxia, defined as:
  • Apgar score ≤5 at 10 minutes, OR
  • Need for resuscitation at 10 minutes, OR
  • Severe acidosis (pH <7.0 or base deficit ≥12-16 mmol/L) 3, 4
• Moderate-to-severe encephalopathy on clinical examination using modified Sarnat criteria with at least 3 of 6 categories (level of consciousness, spontaneous activity, posture, tone, primitive reflexes, autonomic system) scored in the moderate or severe range 3, 4
• Age <6 hours from birth 5, 1, 2

Therapeutic Hypothermia Protocol

Cooling Methods

Both whole body cooling and selective head cooling are equally effective 5, 1:

• Whole body cooling: Target core temperature 33-34°C 5, 1, 3
• Selective head cooling: Target core temperature 34.5°C 6

Critical Timing and Duration

• Initiate within 6 hours of birth - efficacy decreases significantly after this window 5, 1, 2
• Continue for 72 hours of continuous cooling 5, 1, 3
• Rewarm slowly over at least 4 hours at approximately 0.5°C per hour 5, 1, 3

Temperature Monitoring

Avoid temperatures below 32°C as they are less neuroprotective, and temperatures below 30°C cause severe complications 6. Core temperature must be continuously monitored with strict control, targeting 33.5°C ± 0.5°C during passive cooling for transport 4.

Required Facility Capabilities

Cooling should ONLY be conducted in neonatal intensive care facilities with multidisciplinary capabilities 5, 1, 3:

• Intravenous therapy 1, 3
• Respiratory support and mechanical ventilation 1, 3
• Continuous pulse oximetry 1, 3
• Antibiotics and anticonvulsant medications 1, 3
• Transfusion services 1
• Radiology including ultrasound 1
• Pathology testing 1

Supportive Care During Cooling

Respiratory Management

• Maintain adequate ventilation and oxygenation 3
• Target PaCO₂ of 4.5-5.0 kPa 1
• Start resuscitation with room air (21% oxygen) for term infants, titrating based on pulse oximetry 3

Cardiovascular Support

• Maintain systolic blood pressure >110 mmHg 1
• Monitor for and treat hypotension, which is a known complication of cooling 5, 3
• Increased need for inotropic support may occur 3

Metabolic Management

• Initiate intravenous glucose infusion as soon as practical to avoid hypoglycemia 5, 3
• Monitor for thrombocytopenia, a known adverse effect of cooling 5, 3

Seizure Management

• Do NOT administer prophylactic antiepileptic drugs 4
• Implement continuous EEG or amplitude-integrated EEG monitoring as soon as possible to accurately diagnose seizures 4
• Electrographic seizures are rare in the first few hours after birth if the insult occurred during labor and delivery 4

Expected Outcomes

Overall Benefit

• Number needed to treat is 5-9 infants to prevent one case of death or major neurodevelopmental disability 5, 1, 2
• Absolute risk reduction of 151 fewer cases of death or neurodevelopmental impairment per 1000 infants treated at 18-24 months 1, 2

Specific Neurological Benefits

• 48% reduction in cerebral palsy (RR 0.52; 95% CI 0.37-0.72) 1, 2
• 52% reduction in blindness (RR 0.48; 95% CI 0.22-1.03) 1, 2
• 58% reduction in deafness (RR 0.42; 95% CI 0.21-0.82) 1, 2

Effectiveness by HIE Severity

• Moderate HIE: 33% reduction in death or major neurodevelopmental disability (RR 0.67; 95% CI 0.56-0.81) 1, 2
• Severe HIE: 17% reduction (RR 0.83; 95% CI 0.74-0.92) 1, 2

Critical Pitfalls to Avoid

• Never initiate cooling beyond 6 hours of life - efficacy decreases significantly after this window 1, 3
• Never rewarm rapidly - rewarming must occur over at least 4 hours to prevent complications including metabolic instability 5, 1, 3
• Never attempt therapeutic hypothermia without proper monitoring equipment and trained staff 3
• Never implement cooling in facilities lacking multidisciplinary care capabilities 5, 1
• Avoid temperatures below 32°C as neuroprotection decreases, and avoid temperatures below 30°C which cause severe complications 6

Transport Considerations

If an infant qualifies or there is concern for HIE, transfer to a center capable of performing therapeutic hypothermia should be initiated immediately 4. During passive cooling for transport, core temperature must be closely monitored with a target of 33.5°C ± 0.5°C 4.

Long-term Follow-up

All treated infants should be followed longitudinally to assess neurodevelopmental outcomes 5.