Chest Circumference lesson 2

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Christ the King College


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####### Chest circumference ranges 30–33 cm

(12–13 in), usually 2-3 cm < HC

To measure the chest circumference, place

the newborn on his back with the tape measure under the lower edge of the scapulae posteriorly and then bring the tape forward over the nipple line ABNORMAL FINDINGS

a CC less than 30 cm indicates prematurity
an enlarged heart may make the left side of the chest larger


neonatal breast enlargement is a normal response to

falling levels of maternal estrogen at the end of pregnancy

usually occurs in the first week of life and generally resolves



abdominal circumference is approximately same as chest

measured just above the level of the umbilicus

AC is not routinely measured unless there is a suspicion

of abdominal distention due to obstruction in the ga

strointestinal tract.

The neonate’s abdomen usually enlarges after a

feeding due to lax abdominal muscle


####### axillary temperature range is 36°C – 37°C

(97°F – 98°F)

####### average axillary temperature: 37ºC

####### rectal temperature is 0.2-0ºC higher


Conduction – transfer of body heat to a cooler

solid object in contact with the baby

Convection – flow of heat from the newborn’s

body surface to cooler surrounding air

Radiation – transfer of body heat to a cooler solid

object not in contact with the baby

Evaporation – loss of heat through conversion of

a liquid to vapor HEAT LOSS IN NEWBORN Immature temperature regulating system (not capable of shivering) Very little amount of subcutaneous fat to provide insulation Larger body surface area that results in more heat loss (loses heat four times than the adult) Little ability to conserve heat by changing posture and no ability to adjust own clothing in response to thermal stress Takes on the temperature of their environment; this means that newborns can become hypothermic or hyperthermic easily depending on the temperature of the environment

THERMOGENESIS Brown Fat – a special tissue found in mature newborns, helps to conserve or produce body heat by increasing metabolism the greatest amounts of brown fat are found in the intrascapular region, thorax, and perirenal area HEAT PRODUCTION IN NEWBORN

Increasing muscular activity such as by kicking and

crying which also increase metabolic rate and respiratory rate. Immature newborn with poor lung development may not be able to use this mechanism of heat production. Burning brown fat – present only in newborns, begins to form at 17 weeks of gestation, the less mature the newborn the less brown fat

####### Hypothermia occurs when the body temperature

drops below 36 ºC

####### The newborn is most sensitive to hypothermia during

the stabilization period in the first 6-12 hours after birth EFFECTS OF HYPOTHERMIA

Acidosis – increased metabolic rate results in increased

production of carbon dioxide and metabolic waste products result in acidosis Hypoxemia – oxygen is utilized for increase metabolism in order to produce more heat instead of being used for oxygenation of cells and tissues Hypoglycemia – increased metabolic rate increases glucose utilization resulting in depletion of glucose stores and lowering blood glucose levels INTERVENTIONS FOR HYPOTHERMIA

Inform the doctor immediately Remove the wet cloth Place the baby under the heat source Encourage breastfeeding Start oxygen administration if the baby has respiratory distress or cyanosis HYPERTHERMIA

a temperature above 37ºC
although not as common as hypothermia, hyperthermia

can be as equally dangerous CAUSES OF HYPERTHERMIA

Too hot external environment

Too many covers or clothes on baby


problematic as long as it stays above 100 bpm

The newborn’s heart rate increases with activity and may increase

to 180 bpm for short periods of time with vigorous activity and crying

Full term newborns have heart rate that ranges from

120 to 160 bpm the same as FHR. It may go down as slow as 80 bpm when newborn is asleep and may go up to as high as 180 bpm when he is vigorously crying

Rhythm is characterized as sinus arrhythmia, rate increasing

with inspiration and decreasing with expiration Newborn heartbeat is often irregular and heart murmurs may be heard until 6 months of age Take apical pulse and respiratory rate first while he is asleep to obtain accurate results Take temperature last as the newborn may struggle with the placement of thermometer in the axilla


Respirations are activity dependent

The respiratory rhythm is often irregular, a characteristic

known as episodic breathing

The abdomen and chest rise and fall together with breathing


The normal respiratory rate is 30-60 bpm and should be counted

for a full minute when the newborn is quiet

Slows down during the infancy period

The respiratory environment is abdominal or diaphragmatic in

nature, the chest and abdomen should rise at the same time,

and this is carried on during the infancy period

Newborns are obligate nose breathers

Newborns are more at risk to develop infection than the adult

Crying may be beneficial to a newborn

Chest Circumference lesson 2

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