Thermoneutrality is defined as the ambient temperature zone where the neonate’s metabolism is minimal and the core temperature remains stable (36.5-37.5 °C) through passive mechanisms. This zone is very narrow in premature infants, sometimes less than 1°C[1].
Heat exchanges to know:
- Conduction: exchanges by contact (mattress, laundry, hands). Not very important in incubators (1-3% of losses), but major in skin-to-skin or heated cradles. Limit losses by controlling the temperature of the surfaces in contact.
- Convection: exchanges between the skin and the air (about 40% of losses). Depends on the exposed surface, temperature difference and air velocity. Avoid drafts, adjust the air temperature well.
- Radiation: infrared exchanges with surrounding surfaces (about 50% of losses). The walls of the incubator protect direct exchanges with the room. Place the incubator in a room with a stable temperature, avoid sunlight or direct air conditioning.
- Evaporation: water loss through the skin and respiratory tract (7-9% of losses). Very important in premature infants. Limit losses by covering the child, increasing the humidity, or using a plastic cover.
Why is this crucial?
Leaving the thermoneutral zone, even by 1 to 2 °C, has deleterious effects: increased apnea, sleep disruption, slowed weight gain, increased morbidity and mortality. A 2.5°C change in incubator temperature can increase the frequency of apneas by 50%[1].
In practice:
- Measure the child’s internal temperature regularly.
- Adapt the environment (temperature, humidity, clothing) to each clinical situation.
- Limit door openings and objects in the incubator that disrupt airflow.