7. Thermoregulation

Question 1

Why are newborns very susceptible to heat loss?

Answer 1

large body surface area in relation to body mass, limited amount of subcutaneous fat, CNS control of temp not fully developed, immature skin leading to increased evaporation/heat losses, environmental changes (inability to maintain temp)

Question 2

How do newborns attempt to regulate body temp?

Answer 2

non-shivering thermogenesis, increase metabolic rate, increase voluntary muscle activity, peripheral vasoconstriction to decrease heat loss to the skin surface

Question 3

Non-shivering thermogenesis: How is heat produced? What areas on the body have highly vascular adipose tissue? When does production of brown fat begin? What 2 things are consumed? What do preterm infants with smaller stores of brown fat have to rely on?

Answer 3

metabolism of brown fat
neck, scapula, axilla, mediastinum, around kidneys/adrenal glands
26-28 weeks and continues for 3-5 weeks after birth
O2 and glucose
increased O2 consumption and muscle activity to produce heat

Question 4

What are the 4 types of heat loss/gain? Explain each.

Answer 4

1) convection: transfer of heat from infant to surrounding air
2) radiation: heat transfer between infant and a structure surface without direct contact
3) evaporation: transdermal (wet clothes, etc.), exhalation
4) conduction: skin surface to structure surface with direct contact

Question 5

When does cold stress occur? What do infants do to attempt to maintain body temp?

Answer 5

when an infant’s skin temp drops below 36 degrees, will metabolize brown fat

Question 6

List some effects of non-shivering thermogenesis.

Answer 6

increased O2 consumption, hypoglycemia, hypoxemia, metabolic acidosis, apnea, bradycardia, increased PVR, R-L shunting, decreased surfactant production

Question 7

Define NTE.

Answer 7

ambient temp at which an infant has lowest O2 consumption and metabolic rate while maintaining normal body temp
the more premature, the greater temp needed to establish a NTE
and infant gets older, less temp required for NTE

Question 8

What are some ways to maintain NTE?

Answer 8

towel dry skin at delivery, remove wet linen, use pre-warmed blankets, swaddle, apply clothing, overhead radiant warmer, incubator, heated humidifiers, plastic bag