Thermoregulation in a newborn
Introduction:
Normal temperature is maintained if there is a balance
between the generations of heat and its dissipation.
Normal temperature of newborn is 36.3-37.3 ºC axillaries.
Neutral thermal environment (NTE): it is the environment
or conditions under which the core body temperature is normal
with minimal caloric expenditure and oxygen consumption. In
another words, a neutral thermal environment is one that permits
the newborn to maintain normal core temperature with minimum
O2 consumption and caloric expenditure.
Mechanism of Thermoregulation :
Thermoregulation is a balance between heat loss and heat
gain. The main goal is to control the neonate’s environment to
maintain a neutral thermal environment and minimize energy
expenditure. If heat production exceeds heat loss, the temperature
rises and vice versa.
Reason for temperature instability in a premature infant
-
Minimal insulating subcutaneous fat.
Decreased stores of brown fat.
Limited stores of brown fat.
Immature temperature regulation center in the brain.
Extended rather than flexed position.
Relatively large surface area
Decreased response due to drugs ,IUGR or asphyxia
Methods of Heat Loss and Gain:
1. Convection: Where heat loss is aided by surrounding
air currents (keep baby away from drafts and fans).
2. Conduction: Involves loss of heat from the body
because of direct contact of skin with a cooler solid
object.
3. Evaporation: Heat is lost by evaporation of amniotic
fluid from the skin surface immediately after birth.
Insensible water loss and visible sweat .
4. Radiation: Loss of heat to cooler solid objects in the
environment that are not in direct contact with the
newborn. Loss of heat through radiation increases as
these solid objects become colder and closer to
newborn. So, keep the newborn in the center of the
room (away from cold external walls).
Hypothermia
It occurs when body temperature is below 36.3ºC axillary.
Conditions Associated with Hypothermia:
1. Cold environment.
2. Incorrect care of the newborn immediately after birth
e.g., Inadequate drying, insufficient clothing and
separation from the mother.
3. Inadequate warming procedures (before and during
transport).
4. Diseased and stressed newborn.
5. Hypoxia.
Signs and symptoms
1.
2.
3.
4.
5.
A. Initial signs:
Cold feet.
Weak sucking ability or inability to nurse.
Lethargy and weak cry.
Skin color changes from paleness and cyanosis to peripheral
mottling or plethora.
Tachypnea and tachycardia.
B. As the hypothermia persists:
1. Lethargy.
2. Apnea and bradycardia.
3. High risk for hypoglycemia, metabolic acidosis, respiratory
distress,
and
abnormal
clotting
factors
(DIC,
intraventricular hemorrhage, pulmonary hemorrhage).
Nursing Care for Hypothermia:
- The incubator should always be pre warmed before
placing a newborn.
- The use of double- walled incubator.
- The newborn is clothed and warmly wrapped in
blanket when removed from the warm environment of the
incubator for feeding or cuddling.
- Inside or outside the incubator, head covering is
effective in preventing heat loss.
- Compare the newborn’s temperature with the
temperature in the incubator (axillary temperature
procedure).
- Use plastic shield,bubble wrap etc to reduce heat loss
- Use kangaroo care as and when appropriate
Open care:
-
Use radiant warmer for undressed newborn except for
a diaper.
- Skin temperature probe must be placed flat on the
newborn’s skin, usually on the abdomen.
- The servo temperature should be taken every 30
minutes or according to newborn condition in order to
determine, that the newborn’s temperature is maintained
within the proper range.
Incubator care:
-
Ensure that all personnel involved with care are
capable of using the incubator properly,
-
Monitoring the newborn’s temperature and adjusting
the incubator temperature according to the weight of
newborn to maintain a neutral thermal environment.
- Locate the incubator within the nursery environment
away from uninstalled window. The room temperature
should be adequate and room drafts are minimized.
- Encourage parents to visit and hold the newborn as
much as possible, utilizing skin-to-skin contact for
temperature stabilization.
- Use portholes as much as possible during care for the
newborn, instead of opening the larger door. (Temp. of
incubator 28-32ºC up to 35ºC)