What are the optimal thermoregulation strategies for infants in the Neonatal Intensive Care Unit (NICU)?

Optimal Thermoregulation Strategies for NICU Infants

Maintain infant temperature between 36.5°C and 37.5°C from birth through NICU admission using a combination of plastic wrap/bag, radiant warmer, room temperature ≥23°C, and consider adding a thermal mattress for extremely preterm infants (<32 weeks), while continuously monitoring to avoid hyperthermia. 1

Critical Temperature Target and Monitoring

The target temperature range of 36.5°C to 37.5°C must be maintained as a strong predictor of mortality and morbidity outcomes. 1 The International Consensus on Cardiopulmonary Resuscitation emphasizes that admission temperature should be recorded both as a predictor of outcomes and as a quality indicator. 1

• Each 1°C drop below 36.5°C increases mortality risk by at least 28%, demonstrating a clear dose-response relationship. 1, 2
• Hypothermia (<36°C) is strongly associated with respiratory distress syndrome, hypoglycemia, intraventricular hemorrhage, and late-onset sepsis. 1, 2
• Use axillary temperature measurement in the delivery room, though admission temperature method can follow regional practice. 1

Evidence-Based Intervention Bundle for Preterm Infants (<34 Weeks)

Core Interventions (Apply to All Preterm Infants)

Plastic wrap or bag (without drying first) plus radiant warmer is the foundational intervention with the strongest evidence:

• High-quality evidence shows plastic wraps improve survival (RR 1.05,95% CI 1.00-1.10; NNTB 24 infants). 1
• Reduces hypothermia significantly (RR 0.64,95% CI 0.50-0.82; NNTB 3 infants). 1
• Increases mean body temperature by 0.65°C (95% CI 0.42 to 0.87). 1
• Apply immediately after birth without drying the infant first. 1

Environmental temperature ≥23°C (preferably 23-25°C or 26°C for extremely preterm):

• The 2023 International Consensus recommends room temperatures ≥23°C for all preterm infants <34 weeks. 1
• The 2015 guidelines suggested 23-25°C as part of combination interventions. 1
• Quality improvement data shows maintaining delivery room temperature at 74°F (23.3°C) continuously is effective. 3

Radiant warmer settings:

• Preheat to 100% before delivery, then switch to servo-controlled mode after infant placement. 3

Additional Interventions for Extremely Preterm Infants (<32 Weeks)

Consider adding a thermal mattress for infants <32 weeks gestation:

• Observational evidence (612 patients) shows benefit when added to plastic wrap and radiant warmer (OR 0.27,95% CI 0.18-0.42). 1
• The 2023 guidelines state it is "reasonable to consider" thermal mattress addition when hypothermia is identified as a problem, though there is hyperthermia risk. 1
• One RCT showed no benefit, but four observational studies demonstrated significant reduction in hypothermia. 1

Polyethylene cap for head coverage:

• Include as part of the combination approach. 1
• Prevents significant heat loss from the large surface area of the infant's head. 1, 4

Emerging Evidence-Based Interventions

Heated and humidified resuscitation gases:

• One observational study showed benefit (OR 0.20,95% CI 0.08-0.47), though RCT evidence was inconclusive. 1
• Consider when available, particularly for extremely preterm infants. 1

Skin-to-skin care (for stable infants ≥1200 grams):

• Highly effective for infants 1200-2199 grams (RR for hypothermia 0.09,95% CI 0.01-0.64; NNTB 2). 5
• Good evidence supports use for maintaining temperature in late preterm and term infants immediately after birth. 1

Algorithmic Approach by Gestational Age

For Infants <28 Weeks (Extremely Preterm):

1. Set delivery room temperature to 23-26°C continuously 1, 3
2. Preheat radiant warmer to 100% 3
3. Apply plastic wrap immediately without drying 1
4. Apply polyethylene cap 1
5. Add thermal mattress 1
6. Consider heated/humidified gases if available 1
7. Monitor temperature every 15-30 minutes 6

For Infants 28-31 Weeks:

1. Set delivery room temperature to ≥23°C 1
2. Preheat radiant warmer to 100% 3
3. Apply plastic wrap immediately without drying 1
4. Apply polyethylene cap 1
5. Consider thermal mattress if hypothermia is anticipated 1
6. Monitor temperature every 15-30 minutes 6

For Infants 32-33 Weeks:

1. Set delivery room temperature to ≥23°C 1
2. Use radiant warmer 1
3. Apply plastic wrap 1
4. Monitor temperature closely 1

Critical Pitfalls to Avoid

Hyperthermia (>38°C) must be avoided as it increases mortality and morbidity risk:

• Plastic wraps increase hyperthermia risk (RR 3.67,95% CI 1.77-7.61; NNTH 30). 1
• Thermal mattresses combined with plastic wraps further increase hyperthermia risk. 1
• Monitor temperature continuously and adjust interventions if temperature exceeds 37.5°C. 1

Do not use multiple warming interventions simultaneously without close temperature monitoring:

• The combination of plastic bag plus thermal mattress showed increased hyperthermia compared to plastic bag alone. 1
• Quality improvement data shows 6.5% hyperthermia rate even with standardized protocols. 3

Do not delay intervention for temperature stabilization:

• Apply interventions within 10 minutes of birth. 5
• Hypothermia prevention is more effective than rewarming. 4, 7

Avoid these common errors:

• Drying the infant before applying plastic wrap (defeats the purpose of preventing evaporative heat loss). 1
• Setting room temperature too low or not preheating the delivery room. 3, 7
• Failing to preheat the radiant warmer before delivery. 3
• Not switching radiant warmer to servo-control mode after infant placement. 3

Quality Improvement Considerations

Standardization and team training are essential:

• Multidisciplinary approach involving obstetrics, neonatology, and nursing reduces hypothermia from 44% to 0%. 7
• Real-time feedback and continuous monitoring sustain improvements. 7
• Target rate should be <10% hypothermia, with goal of 0% moderate hypothermia. 3

The thermoneutral environment minimizes energy expenditure and oxygen consumption, leading to enhanced growth, decreased respiratory support, improved glucose stability, and reduced mortality. 8