Thermoregulation Flashcards
Describe the mecahnism of heat loss through convection and midwifery interventions to minimise this heat loss
Transfer of heat from the neonate through an air or liquid
eg. if the bath water is cooler than the neonate, cool draughts
- prevent draughts
- plastic wraps for VLBW infants
- ensure bath temp is 38-40
- prewarm wraps, hats, rooms, incubators, breast milk
Describe the mecahnism of heat loss through conduction and midwifery interventions to minimise this heat loss
Transfer of heat from the neonate to another solid surface in direct contact
eg. cold hands, xray plate, stethescope, scales
- Ensure wraps are warmed (uses conduction conversely)
- use warm skeets and blanekts
- prewarm the incubator surface
- warm objects like plates, scales, stethescopes
- skin to skin with parents
Describe the mecahnism of heat loss through evaporation and midwifery interventions to minimise this heat loss
Transfer of heat from the neonate through transepidermal water loss
eg. amniotic fluid as it evaporates, water from skin and mucous membranes
more premature neonate = thinner skin, leading to increased potential for heat loss via evaporation
- plastic wrap for VLBW infants
- dry with warmed towels
- place in a preheated and prehumidified incubator
- limit the use of radiant warmers
- prewarm any lotions or soaks
Describe the mecahnism of heat loss through radiation and midwifery interventions to minimise this heat loss
transfer of radiant heat from the neonate to cooler surrounding surfaces not in direct contact with skin
eg. windows, incubator walls
- move neonates away from doors, windows, cold walls
- use radiant warmer for resus and procedures
- ensure incubators are prewarmed
- ensure neonate is dressed where possible
Identify conditions that may lead to hypothermia
- prematurity
- LBW/FGR
What are the consequences of unresolved hypothermia
- hypoglycaemia
- hypoxia/resp distress
- metabolic acidosis
- shock
- seizures
- death
Define the neutral thermal environment and explain its role in facilitating thermoregulation
- maintenence of an infants temperature WNL 36.6-37.2
- a state of metabolic stability with minimal oxygen and glucose consumptiom
- important to avoid respiratory distress, cold stress or hypolycaemia and their associated consequences
Explain why newborns are vulnerable to heat loss
- large surface area to body ratio
- limited brown fat stores
- limited subcutaneous fat
- thin skin
- inability to shiver
- immature metabolic mechanisms
Explain the metabolic response to cold stress
When infants are exposed to cold stress, they rely on non shivering thermogenesis to maintain a stable body temperature. When n infants rely on this for too long without other mechanisms of conserving heat, the metabolism of brown fat expends a significant amount of oxygen and sugar. Overtime this can lead to hypoxia and hypoglycaemia. Due to the high oxygen demands which NST requires, the body engages in anabolic metabolism, which also leads to metabolic acidosis, and can then cause pulmonary vasoconstruction, shock and death.
Describe Non Shivering Thermogenesis as a neonatal adaptation for thermoregulation
Infants do not have the ability to shiver to generate heat, unlike adults. They rely on thermogenesis through the metabolism of brown fat stores. Thermal receptors detect the cold and stimulate the activation of the sympathetic nervous system, and release of noradrenaline at sites of brown fat. This stimulates the metabolism of brown fat using oxygen and glucose to generate heat which is transferred to the skin through conduction between tissues, and the infant uses to maintain their temperature within normal limits
Signs and symptoms of hypothermia
- lethargy
- hypotonia
- mottled skin
- decreased feeding
- deceased weight gain
- apnoea
- tachypnoea
- cool extremities
Midwifery management of hypothermia
