Newborn Physiologic Adjustments (Thermogenic System) Flashcards
During the first _____ hrs after birth the neonate attempts to achieve thermal balance in adjusting to eh extrauterine environment temperature.
12 hrs.
What is thermoregulation?
Is the maintenance of balance between heat loss and heat production.
Newborns attempt to stabilize their core body temp within a narrow range.
What is a common and dangers problem due to excessive heat loss?
Hypothermia
Why are newborns so susceptible to hypothermia?
Thin layer of subcutaneous fat.
Blood vessels very superficial.
Why does the blood vessels being superficial in newborn cause heat loss?
Changes in environmental temp alter the temp of the blood, thereby influencing temp regulation centers in the hypothalamus.
What is the thermo goal for care for newborns?
Neutral thermal environment in which heat balance is maintained.
Explain neutral thermal environment.
Is the ideal environmental temp that allows the neonate to maintain a normal body temp that allows the neonate to maintain body temp to minimize oxygen and glucose consumption.
Heat loss in newborns occurs by what four modes?
- Convection
- Radiation
- Evaporation
- Conduction
What is convection?
Is the flow of heat from the body surface to cooler ambient air.
What are some interventions for convection heat loss?
Nursery is keep at 75.2 F and 24 C.
Cap and swaddle infants to prevent.
What is Radiation?
Is the loss of heat from the body surface to a cooler solid surface not in direct contact but in relative proximity.
What are some interventions for radiation heat loss?
Cribs and examining tables are placed away from outside windows, and care is taken to avoid direct air drafts.
What is Evaporation?
Is the loss of heat that occurs when a liquid is covered to a vapor. In the newborn heat is loss by evaporation occurs as a result of vaporization of moisture from skin.
What are some interventions for evaporation heat loss?
Dry the infant quickly and thoroughly.
What is the most significant cause of heat loss in the first few days of life?
Evaporation heat loss, as a component of insensible water loss.
What infant is more prone to more severe evaporation heat loss?
The less mature newborn.
What is conduction?
Is the loss of heat from the body surface to cooler surfaces in direct contact.
What are some intervention to prevent conduction heat loss?
Newborns placed in a warmed crib.
Scales warmed or coved before weighing newborn.
What is one method for promoting thermoregulation and maternal newborn interaction?
Place naked newborn on mother’s bare chest and over both with a blanket.
What does skin-to-skin contact reduce and enhance?
Reduces conductive and radiant heat loss
Enhances newborn temperature control and maternal-infant interaction.
In response to cold the neonate attempts to generate heat by increasing muscle activity. What is this called?
Thermogenesis
What thermogenesis techniques will infants perform?
Crying
Appearing restless
Position of Flexion
Constriction of blood vessels
In an effort to conserve heat, what might an infant do?
Obtain the position of flexion. This reduces body surfaces exposure to the environment.
What will an infant do to reduce internal heat loss?
Constricting peripheral blood vessels.
Newborns produce heat though…
Non shivering thermogenesis
How is non shivering thermogenesis accomplished?
By metabolism of brown fat.
Secondarily by increased metabolic activity in the brain, heart, and liver.
Where is brown fat located?
Located in superficial deposits in the inter scapular region and axillae and in deep deposits at the thoracic inlet, along the vertebral column, and around the kidneys.
How do reserves of brown fat deplete?
Usually present for several wks after birth, are rapidly depleted with cold stress.
What happens to the respiratory rate in response to cold stress?
Increases due to need for O2
In the cold-stressed infant O2 consumption and energy are diverted from maintaining normal brain and cardiac function and growth to….
Thermogenesis for survival.
What happens if the infant cannot maintain adequate O2 tension?
Vasoconstriction follows and jeopardizes pulmonary perfusion. As a consequences the Po2 is decreased, and the blood pH drops.
What can decreased pulmonary perfusion and O2 tension do?
Maintain or reopen the right-to-left shunt across the ductus arteriosus.
What is considered hyperthermia in newborns?
Temp greater than 37.5 C or 99.5 F is considered to be abnormally high
What is hyperthermia in usually caused by?
Related to sepsis or a decrease in heat loss.
Infants who are overheated because of environmental factors such as being swaddled in too many blankets exhibit signs of heat-losing mechanisms:
Skin vessels dilate
Skin appears flushed
Hands and feet are warm to touch
Infant assumes a posture of extension
Hyperthermia b/c of sepsis appears stressed:
Vessels in the skin are constricted
Color is pale
Hands and feet are cool
Serious overheating of newborn can cause…
Cerebral damage from dehydration or even heat stroke and death.
