thermoregulation of the newborn

what is thermoregulation?

attempt to maintain balance between heat loss and heat production

-newborns cant stabilize their temperatures until 8-10 hours after birth

what places newborns at risk for heat loss?

-thin layer of subcu fat

-superficial blood vessels

what is convection?

flow of heat form body surface to cooler air

how can you prevent heat loss from convection?

-keep temp in hospital between 72-78 degrees

-keep humidity between 30-60%

-if baby is in open bassinet, wrap in blanket and put a cap on them

what is radiation?

loss of heat from body surface to a cooler solid surface; not by direct contact but just something that is close by

how can you prevent heat loss from radiation?

-place bassinets away from windows or cold things

-avoid direct air drafts

what is evaporation?

heat loss when liquid is converted to vapor

how can you prevent heat loss from evaporation?

-dry newborn immediately after birth and bathing

what is conduction?

loss of heat from the body surface to cooler surfaces in direct contact

how can you prevent heat loss from conduction?

place on prewarmed bed under radiant warmer

prewarm scales for weighing or put protective cover over them

what protocols do hospitals follow to prevent heat loss?

-drying infant immediately

-skin to skin

-put a cap on babies head

-place baby under radiant warmer

how does the neonate attempt to generate heat?

thermogenesis by increasing muscle activity

-there is an inc in metabolic activity that increases oxygen and glucose consumption

how can you tell an infant is cold?

they may cry or appear restless

cool to touch

acrocyanosis

what position may a newborn get in to conserve heat?

position of flexion

how do newborns produce heat?

nonshivering thermogenesis-

metabolism of brown fat and increased metabolic activity in the brain, heart, and liver

how is brown fat different from regular fat?

-it has a richer vascular and nerve supply

-heat is produced by intense lipid metabolic activity and increase heat production by 100%

-reserves of brown fat are present for several weeks but are rapidly depleted in cold stress

-full term infant has greater stores of brown fat than a preterm infant

what happens when a neonate's temp drops?

-vasoconstriction to conserve heat

-if hypothermia isn't corrected, will progress to cold stress (which inc metabolic and oxygen demands)

-respiratory rate inc in response to inc need for oxygen

-O2 consumption is used for thermogenesis instead of brain and cardiac function

what does the vasoconstriction caused by hypothermia do to the lungs?

jeopardizes pulmonary perfusion

-PO2 is decreased

-blood pH drops

-surfactant synthesis is altered

-can cause resp distress

what can dec pulmonary perfusion and oxygen tension cause?

reopening the right to left shunt across the ductus arteriosus

what are metabolic complications of cold stress?

-basal metabolic rate increases

-anaerobic glycolysis occurs (this causes inc production of acids)

-metabolic acidosis results (if pulm function is altered then resp acidosis also)

-hyperbilirubinemia caused by excessive fatty acids

-glycolysis depletes glucose stores and causes hypoglycemia

when babies metabolize brown fat, what does this put them at risk for?

high levels of ketones which are acids so lead to metabolic acidosis

what are three main complications of cold stress?

-resp distress (hypoxia)

-hypoglycemia

-metabolic acidosis

why are LBW infants at inc risk for cold stress?

-smaller muscle mass

-fewer deposits of brown fat

-lack of subcu fat

-poor reflex control of capillaries

what is the recommended temp for a healthy term newborn?

97.7-99.5 axillary

what is the recommended temp for a preterm infant?w

97.3-98.4 axillary

what is one advantage the newborn has?

fetal hemoglobin has increased capacity to carry oxygen and allows the infant to survive for longer periods with decreased oxygen tension

what are three primary methods for maintaining neutral thermal environment?

-use of incubator

-radiant warming panel

-open bassinet with cotton blankets