2. Four ways a newborn may lose heat to the environment.
Most cooling of the newborn occurs during the first minutes after
birth.
HOW DOES A NEWBORN LOOSES HEAT?
3. PHYSICS OF HEAT TRANSFER
• Conduction-transfer of energy from molecule of body to
molecule of solid object in contact
• Convection-transfer of thermal energy from body to molecule
of adjacent gas
• Evaporation- total heat transfer by energy carrying water
molecules from skin & resp tract to drier atmosphere
• Radiation-heat loss in form of electromagnetic waves b/w
body & environmental surface not in contact with body
4. MECHANISM OF HEAT LOSS
HEAT LOSS
THROUGH
DETERMINING
FACTORS
EXAMPLES
CONVECTION Ambient temperature
Air flow
Draughts, blowing of
cold oxygen
CONDUCTION Temperature difference
between the skin and the
surface
Cold exam tables,
weighing tray,
x-ray plates,
mattress
RADIATION Via infrared
electromagnetic waves
Walls of room, incubator
EVAPORATION Humidity
Thickness of skin
Transepidermal water
loss, respiratory tract
5. TEMPERATURE DISTURBANCES
• Normal core body temp.- 36.5*C - 37.5*C
• Hypothermia is defined as core body temp. < 36.5*C
• Hyperthermia is defined as core body temp.>37.5*C
6. Normal range
Cold stress
Moderate hypothermia
Severe hypothermia Outlook grave, skilled
care urgently needed
Danger, warm baby
Cause for concern
37.5o
36.5o
36.0o
32.0o
AXILLARY TEMPERATURE IN THE
NEWBORN ( 0C)
7. HYPOTHERMIA
CLINICALLY :
• Baby’s feet are warm &pink – Thermal comfort
• Feet are cold, abdomen is warm - Cold stress
• Both feet and abdomen are cold to touch - Hypothermia
8.
9. ADVERSE CONSEQUENCES OF
HYPOTHERMIA
• High O2 consumption hypoxia, bradycardia
• High glucose usage hypoglycemia / decreased glycogen
stores
• High energy expenditure reduced growth rate, lethargy,
hypotonia, poor suck/cry
• Low surfactant production RDS
• Vasoconstriction poor perfusion metabolic acidosis
• Delayed transition from fetal to newborn circulation
• Thermal shock DIC death
10. WHY ARE PRETERMS PRONE TO DEVELOP
HYPOTHERMIA
• High surface area to volume ratio
• Thin non-keratinized skin
• Lack of insulating subcutaneous fat
• Lack of thermogenic brown adipose tissue (BAT)
• Inability to shiver
• Poor vasomotor response
11. NON SHIVERING THERMOGENESIS
• Heat is produced by increasing the metabolism especially in
brown adipose tissue
• Blood is warmed as it passes through the brown fat and it in
turn warms the body
12. THERMOREGULATION
• Heat gain/loss controlled by hypothalamus and limbic system
• Thermoregulatory system immature in newborns (esp premature newborn)
• In term infant, response to cold stress relies on oxidation of brown
fat
• Development begins 20th wk until shortly after birth (comprises 1-4% body
wt at that time)
• High concentration stored TG’s
• Rich capillary network densely innervated by sympathetic nerve endings
• Temperature sensors on posterior hypothalamus stimulate pituitary to
produce thyroxine (T4) and adrenals to produce norepinephrine
• Found near highly perfused organs resembling high-collared vest
• Sites- perinephric, inetrscapular,nape,axilla
13. • Thermogenesis mediated by UCP1 (found only in BAT)
• BAT is rich in 5-monodiodinase(converts T4 in T3)
• Lipolysis stimulated energy produced in form of heat in mitochondria instead of
phosphate bonds by uncoupling protein-1 (thermogenin)
THERMOREGULATION
16. THERMONEUTRAL ZONE
A neutral thermal temperature is the body temperature at
which an individual's oxygen use and energy expenditure are
minimized.
• Minimal metabolic rate
• Minimal oxygen consumption
17. MEAN TEMP NEEDED TO PROVIDE
THERMAL NEUTRALITY
B.Wt
(Kg)
35* C 34*C 33*C 32*C
1.0 1st 10
days
After 10
days
After 3
wks
After 5
wks
1.5 For 10
days
After 10
days
After 4
wks
2.0 For 2
days
After 2
days
After 3
wks
>2.5 For 2
days
After 2
days
18. THERMOREGULATORY ZONE
• It refers to environmental temperature beyond TNE range, at which
baby would be able to maintain its body temp.but by increasing its
BMR.
19. MANAGEMENT
WARM CHAIN:
A set of ten steps carried out at birth and later to reduce the chances of
hypothermia
1.Thermal care in delivery room
2.Warm resuscitation
3.Immediate drying
4. Skin to skin contact
5.Breast feeding
6.Postpone bathing /weighing
7.Clothing
8.Rooming in
9.Warm transportation
10.Training and awareness
21. MANAGEMENT OF COLD STRESS
(MILD HYPOTHERMIA)
• Cover adequately – remove cold clothes and replace with warm
clothes
• Warm room and bed
• Take measures to reduce heat loss
• Ensure skin to skin contact with mother
• Breast feeding
22. MANAGEMENT OF MODERATE
HYPOTHERMIA
• Take measures to reduce heat loss
• warm room and beds
• Skin to skin contact with mother
• Apply warm towels
• Provide extra heat - incubator, warmer, heater if available
• Recheck temperature every 15-30 min.
23. NEONATAL COLD INJURY
(SEVERE HYPOTHERMIA)
• LBW and term infants with CNS disorders
• Have bright red colour due to failure of dissociation of oxy Hb
at low temperature.
24. MANAGEMENT OF NEONATAL COLD
INJURY
• Immediate transfer to incubator/radiant warmer
• Slow or rapid warming of the baby (setting abdominal temperature 10c higher
than core temperature / setting warmer temperature at 36.50c)
• Oxygen
• Fluid bolus (NS – 10-20ml/kg) and 10% dextrose(60-80 ml/kg/day) infusion
• Antibiotics if needed.
• Inj. Vitamin k 1mg/kg for term and 0.5mg/kg for preterm babies
• Exchange blood transfusion if DIC is suspected
• Inj. Hydrocortisone(10mg/kg/day) if sclerema
25. INTERVENTIONS FOR
TEMPERATURE CONTROL
COMMUNITY TRANSPORT HOSPITAL
Warm chain
Kangaroo mother
care(KMC)
KMC
Thermocole boxes
with prewarmed
linen
Warm water
transport incubator
Electrically
operated transport
incubator
Plastic bubble
sheet
KMC
Delivery room
Post natal ward
NICU
Transport
26. HYPERTHERMIA IN NEW BORN
• Axillary temperature more than 37.50c
• ETIOLOGY :
• High environmental temperature
• Sepsis
• Iatrogenic – use of extra heat source, excessive clothing,
phototherapy
• Dehydration
• CNS damage with injury to hypothalamic centre
27. HYPERTHERMIA
ENVIRONMENTAL INCREASED ENDOGENOUS
HEAT (SEPSIS)
Hot skin, extremities hot and
flushed
Active sweating in full term
neonate
Extremities cold, pale and blue
Not sick looking Lethargic and sick looking
Foot temperature <30c cooler
than abdominal skin temperature
Foot temperature >30c cooler
than abdominal skin temperature
28. MANAGEMENT OF HYPERTHERMIA
• Remove source of heat
• Check the equipment for proper settings and functioning
• Breast feeding and IV fluids if not able to feed
• Temperature between 37.50c to 390c
– Undressing tight clothes / excessive clothes
– Exposing the baby to room temperature / Shifting baby to cool
environment
• Cooling with warm water(20c less than baby’s body temperature) if
temperature more than 390c
• Rule out infection
