- Physiological Vulnerabilities and Thermal Management
- Respiratory Management, ELBW, and Periviable Birth
Physiological Vulnerabilities and Thermal Management
A preterm birth is not just an early birth, as the physiology is meaningfully different, and it changes how you approach every step of resuscitation. The same framework applies, but with less margin for error.
Physiological vulnerabilities of the preterm infant
Four characteristics of preterm physiology increase the complexity and risk of resuscitation:
- Surfactant deficiency: the preterm lung lacks adequate surfactant, making alveolar recruitment more difficult and increasing the risk of ventilation-induced lung injury
- Immature skin barrier: thin, poorly keratinised skin allows rapid evaporative water and heat loss, making hypothermia an immediate risk from the moment of delivery
- Fragile germinal matrix: the subependymal germinal matrix, present until approximately 32–34 weeks, is highly vascular and vulnerable to haemorrhage under conditions of hemodynamic fluctuation, rapid fluid shifts, or hyperosmolar drug administration
- Poor glycogen stores: preterm infants have limited hepatic glycogen, making hypoglycaemia a predictable post-resuscitation complication that occurs faster and at lower threshold than in term infants
The preterm thermoprotection bundle
Preventing hypothermia in the preterm infant begins before delivery, not after. The thermoprotection bundle should be activated as soon as a preterm birth is anticipated (Table 15):
Step | Action | Detail |
|---|---|---|
| Room temperature | Increase to 23-25°C | Pre-warm the delivery room, not just the radiant warmer |
| Polyethylene wrap | Place the infant in a plastic wrap or bag without drying (head out) | For infants <32 weeks; wrap immediately at delivery |
| Chemical thermal mattress | Place under wrap on the radiant warmer surface | Adds conductive warming beneath the infant |
| Radiant warmer | Pre-warm; set to manual 100% initially | Switch to servo-control once temperature probe is placed |
| Hat | Apply knitted or polyethylene hat after wrapping | Reduces evaporative and radiant heat loss from the head |
| Temperature check | Delay axillary temperature until 10-15 min post-stabilisation | Avoid unwrapping prematurely |
The target admission temperature for preterm infants is 36.5-37.5°C. Hypothermia on admission to the NICU is independently associated with increased mortality and morbidity, as every degree below 36.5°C matters.
Cord management in preterm infants
Deferred cord clamping of at least 30-60 seconds is recommended for preterm infants who do not require immediate resuscitation, as it provides a placental transfusion that improves iron stores, circulating blood volume, and reduces the need for transfusion.
When DCC is not feasible, cord milking may be considered for infants at ≥28 weeks gestation. However, cord milking should not be performed in infants below 28 weeks of gestation, as the haemodynamic fluctuation associated with the procedure increases the risk of intraventricular haemorrhage in the most immature germinal matrix.
Oxygen management in preterm infants
The initial FiO₂ for preterm infants differs from term. Initiating resuscitation in room air (21%) is appropriate for term infants, but preterm infants (particularly those below 35 weeks) should begin with a blended oxygen concentration of 21-30%. The SpO₂ targets by minute of life are the same as for term infants (see Table 6), but the blended gas source allows more precise titration toward those targets.
Avoid hyperoxia in preterm infants. Oxygen free radical injury is a significant contributor to retinopathy of prematurity, chronic lung disease, and necrotising enterocolitis. The goal is to reach target SpO₂ using the minimum effective FiO₂
Medically reviewed by: Kim Murray, RN, MS., Medical Educator
