Therapeutic hypothermia is a well-established intervention for neonates with hypoxic-ischemic encephalopathy (HIE), aimed at reducing the extent of brain injury following perinatal asphyxia:
Indications for Therapeutic Hypothermia
- Gestational age ≥ 36 weeks and birth weight ≥ 1.8 kg.
- Evidence of perinatal asphyxia:
- Apgar score ≤ 5 at 10 minutes.
- Cord or arterial blood pH < 7.0 or base deficit ≥ 16 mmol/L within the first hour.
- Signs of moderate to severe encephalopathy, such as:
- Altered consciousness (lethargy, stupor, or coma).
- Hypotonia or abnormal reflexes (e.g., absent suck).
- Seizures.
- Onset of hypothermia should occur within 6 hours of birth.
Mechanism of Action
Therapeutic hypothermia works by reducing cerebral metabolic demand, slowing neuronal death pathways, and attenuating secondary energy failure. This helps to minimize neuronal injury caused by oxidative stress, excitotoxicity, and inflammation.
Protocols for Therapeutic Hypothermia
- Method:
- Whole-body cooling: Target rectal temperature of 33°C–34°C.
- Selective head cooling: Cool the scalp while maintaining mild systemic hypothermia.
- Duration:
- 72 hours of cooling, followed by gradual rewarming over 6–12 hours (0.5°C/hour).
Monitoring During Cooling
- Continuous temperature monitoring (rectal probe).
- Neurological examination and amplitude-integrated EEG (aEEG) to assess for seizures.
- Regular blood gas, glucose, electrolytes, and coagulation studies.
- Monitor for complications such as:
- Bradycardia (common and tolerated at 80–100 bpm).
- Coagulopathy.
- Hypotension.
Outcomes
- Therapeutic hypothermia has shown to:
- Decrease the risk of death or significant neurodevelopmental impairment.
- Improve long-term neurodevelopmental outcomes in survivors.
- It does not benefit infants with mild encephalopathy or when initiated beyond 6 hours of life.