Management of Severe Hypothermia in Neonates
For neonates with severe hypothermia (temperature <36°C), begin immediate active rewarming using radiant warmers or servo-controlled incubators, but the evidence does not support choosing either rapid (≥0.5°C/hour) or slow (<0.5°C/hour) rewarming rates over the other—both approaches are acceptable. 1
Immediate Rewarming Interventions
Primary Rewarming Strategy
- Place the hypothermic neonate immediately under a radiant warmer or in a servo-controlled incubator to restore normothermia (target temperature 36.5-37.5°C) 1, 2, 3
- Do not delay rewarming while investigating the underlying cause 3
- Monitor temperature continuously or every 15-30 minutes during the rewarming process 3
Rewarming Rate Considerations
The 2015 International Consensus on CPR and ECC explicitly states that evidence is insufficient to recommend either rapid (≥0.5°C/hour) or slow (<0.5°C/hour) rewarming for unintentionally hypothermic newborns 1. This represents a departure from older teaching that advocated for slow rewarming to avoid apnea and arrhythmias.
Important distinction: This recommendation applies to unintentional/iatrogenic hypothermia after birth, not therapeutic hypothermia induced for hypoxic-ischemic encephalopathy, which requires slow rewarming over at least 4 hours after the 72-hour cooling period 1, 4
Recent research provides conflicting perspectives:
- One 2021 randomized trial in low-birth-weight preterm neonates found rapid and slow rewarming equally safe and effective, with similar mortality and morbidity outcomes 5
- A 1984 study reported 81% survival with rapid rewarming versus historical 25-50% mortality with gradual rewarming 6
- A 2009 case report of profound hypothermia (25°C) demonstrated successful outcome with slow rewarming 7
Critical Concurrent Management
Metabolic Monitoring and Support
- Check blood glucose immediately upon recognition of hypothermia, as hypothermia strongly predicts hypoglycemia 2, 3
- Treat hypoglycemia promptly per standard protocols if present 2
- Monitor for metabolic acidosis with blood gas analysis, as hypothermia worsens acidosis 2
- Continue glucose monitoring throughout rewarming 3
Respiratory Support
- Position the neonate in "sniffing" position to maintain airway patency 2
- Provide supplemental oxygen as needed based on pulse oximetry monitoring 2
- Assess for need of positive pressure ventilation if respiratory effort is inadequate 2
Prevention of Hyperthermia During Rewarming
Hyperthermia (>38.0°C) must be avoided during rewarming as it is associated with increased mortality, seizures, and neurologic injury 1, 3. The 2024 International Consensus noted that rapid rewarming was associated with hyperthermia in one observational study (12.5% incidence), though causality remains unclear 1.
Specific Precautions
- Set servo-controlled warmer temperature appropriately (typically 36.5-37.0°C) 3
- Avoid excessively high warmer settings 3
- Do not use thermal mattresses in term infants as they increase hyperthermia risk 3
- Monitor temperature continuously to prevent overshoot hyperthermia 3
Special Populations
Preterm Infants (<32 weeks gestation)
For prevention of hypothermia in preterm infants, use a combination of interventions including 1:
- Environmental temperature 23-25°C
- Plastic wrapping without drying
- Cap
- Thermal mattress
- Warmed humidified resuscitation gases
However, once hypothermia has occurred, the rewarming approach follows the same principles as term infants 1
Common Pitfalls to Avoid
- Do not delay rewarming while searching for the etiology of hypothermia 3
- Do not assume slow rewarming is safer based on outdated teaching—current evidence does not support this preference 1
- Do not create iatrogenic hyperthermia through overly aggressive rewarming settings 1, 3
- Do not forget to check glucose immediately, as this is a critical concurrent complication 2, 3
- Do not confuse unintentional hypothermia management with therapeutic hypothermia protocols for hypoxic-ischemic encephalopathy, which require different rewarming strategies 1, 4