Thermoregulation in the newborn

neutral thermal environment

an environment that maintains body temperature with minimal metabolic changes and/or oxygen consumption

cold stress

a term that describes excessive heat loss that leads to hypothermia and results from utilization of compensatory mechanisms to maintain neonates body temperatures

brown fat

also referred to as nonshivering thermogenesis, a highly dense and vascular adipose tissue that is unique to neonates

Sx of Cold Stress

auxillary temp at or below 36.5C (97.6F), coolskin, lethargy, pallor, tachypnea, grunting, hypoglycemia, hypotonia, jitteriness, weak suck

process of cold stress

decrease of environmental temps lead to decrease in body temp leading to an increase in respiratory rate and heart rate leading to and increase in oxygen consumption, depletion of glucose and a decrease in surfactant which leads to respiratory distress

factors that negatively affect thermoregulation

decreased subcutaneous fat, decreased brown fat in preterm neonates, large body surface, loss of body heat from convection, radiation, conduction, and evaporation

reasons preterm neonates at a higher risk for thermoregulation problems

higher body surface area to body mass ratio, higher metabolic rate, limited and immature thermoregulatory abilities

Neonate's response to cold

increase in metabolic rate, increase in muscle activity, peripheral vascular constriction, and metabolism of brown fat

how is heat produced from brown fat

intense lipid metabolic metabolism of the brown fat

convection

loss of heat from the neonate's body surface to cooler air currents such as air conditioners or oxygen masks

evaporation

loss of heat that occurs when water on the neonate's skin is converted to vapors such as during bathing or directly after birth

locations of brown fat

neck, thorax, axillary area, intrascapular areas, and around the adrenal glands and kidneys

how are brown fat stores rapidly depleted

periods of cold stress

risk factors for cold stress

prematurity, SGA, hypoglycemia, prolonged resuscitation efforts, sepsis, neurological, endocrine, or cardiorespiratory problems

who has limited brown fat

preterm neonates

nursing actions for cold stress

prevent, skin to skin, swaddle, put cap on head, place in warmer, monitor temps, obtain heel stick to assess for hypoglycemia

radiation

transfer of heat from the neonate to cooler objects that are not in direct contact with the neonate such as the cold walls of the isolette or cold equipment near the neonate

conduction

transfer of heat to cooler surface by direct skin contact such as cold hands of caregivers or cold equipment