Thermoregulation - Neonate: Nursing

Video summary

Thermoregulation is an important process for neonates, as their immature body systems can easily become overloaded. Neonatal thermoregulation is different from that of children and adults because of their predisposition to heat loss. That's because their skin is relatively thin, their blood vessels are closer to the skin's surface, there's less subcutaneous fat, and because they are small, they have a high surface area to body mass ratio compared to a child or adult.

Neonates conserve heat when exposed to cooling by assuming a flexed position; or through peripheral vasoconstriction; normal metabolic processes; as well as metabolizing brown adipose tissue. If an infant becomes cold, clinical manifestations can include relatively pale and mottled skin; peripheral or central cyanosis; signs of respiratory distress; apnea, and bradycardia. Behavioral manifestations can include lethargy, poor muscle tone, as well as a weak cry, and weak suck. Priority goals of care include preventing excessive heat loss and providing supportive care if cold stress occurs. Client and family education is focused on how to maintain thermoregulation at home and when to notify the healthcare provider.

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Content Reviewers

Viviana Popa, MD,Lisa Miklush PhD, RN, CNS,Gabrielle Proper, RN, BScN, MN

Thermoregulation is the ability to balance between heat loss and heat production with the goal of maintaining a steady core temperature. Neonatal thermoregulation is different from that of children or adults for several reasons, including the neonatal predisposition to heat loss, and their unique means of generating heat on account of their brown adipose tissue, or BAT for short. Now, let’s look at the physiology of neonatal thermoregulation. There are some ways a neonate produces and conserves heat in order to keep their internal temperature within a normal range. First, neonates conserve heat when exposed to cooling by assuming a flexed position, which helps to decrease the amount of surface area exposed to the external environment. Okay, heat can be lost in four ways: by radiation, conduction, evaporation and convection. Heat loss by radiation is the transfer of heat from the body to another object without touching it. So, if the baby’s bed is next to a cold window, the baby’s body heat can quickly be transferred from the baby toward the cold window. Heat loss by conduction is the transmission of heat from the body to another object by touching it. So if the baby is weighed on a cold scale, the baby will lose heat as it is transferred to the scale. Next is convection, where heat is carried away by cooler air.

This happens when the baby leaves the cozy warm uterus and enters a cooler, drafty outside world, and the baby’s body heat is transferred to the environment by air currents. Lastly, evaporation is the loss of heat by transferring liquid into gas, which can happen when moisture from the skin and lungs evaporates and turns to vapor. Immediately after birth, babies can lose a lot of heat through the evaporation of amniotic fluid. Now, when a neonate is exposed to excessive cooling, or cold stress, a cascade of events occur in an attempt to maintain a stable temperature. First, peripheral and central neurosensors send signals to the hypothalamus, which activates the release of norepinephrine. The release of norepinephrine has a number of effects. First, it causes peripheral vasoconstriction, which helps keep heat in the core of the body. If peripheral vasoconstriction continues, though, tissue perfusion decreases, causing hypoxia, anaerobic metabolism, and eventually lactic acidosis. Acidosis can cause pulmonary vasoconstriction, and this can lead to a pressure increase in the pulmonary circulation, leading to right to left shunting through the ductus arteriosus and foramen ovale, and ultimately resulting in hypoxia.