Newborn Physiology

Question 1

Where are the most critical changes in a newborn?

Answer 1

Respiratory and cardiac system

Question 2

What chemical events initiate breathing?

Answer 2

Mild asphyxia, hypoxia⇒ decreased PO2, pH, and increased CO2

Question 3

Which 2 things prompt fetal circulatory structures to begin closing?

Answer 3

First breath plus cutting umbilical cord

Question 4

When does surfactant production begin?

Answer 4

Around 24-25 weeks

Question 5

When does surfactant production peak?

Answer 5

34-36 weeks

Question 6

What is surfactant made up of?

Answer 6

Lecithin & sphingomyelin in a 2:1 ratio (ideally)

Question 7

Respiratory rate of a newborn

Answer 7

60-70, up to 100
Will decrease to 30-60

Question 8

Signs of respiratory distress in newborns

Answer 8

Grunting, flaring, retracting, tachyphea, cyanosis, pallor, poor muscle tone, apnea

Question 9

Which circulatory structures close on the fetus to transition into adult circulation?

Answer 9

Foramenovale, ductus arteriosus, ductus venous

Question 10

Are crackles a normal finding when listeningto a newborn’s lungs?

Answer 10

Yes, for the first few hours, infants have a lot of mucus innings

Question 11

When does the foramen ovale close?ductus arteriosus?ductus venosus?

Answer 11

Foramen ovale: Closes functionally 1-2 hours after birth (permanently after 2-4 months)
Ductus arteriosus: closes functionally 10-15 hours after birth (permanently in 1-2 weeks)
Ductus venosus: closes functionally soon after birth (permanently at 1-2 weeks)

Question 12

Where are the pressure changes when the transition from fetal to neonatal circulation occurs?

Answer 12

Heart / pulmonary & systemic circulation

Question 13

When should an infant’s cardiovascular assessment be performed?

Answer 13

When the infant is asleep/quiet

Question 14

What is an infant’s heart rate normally?

Answer 14

110-160

Question 15

What is a passing oximetry screen for an infant?

Answer 15

≥ 95% 02 sat in right hand or foot
≤ 3% difference between right hand and foot

Question 16

What is a failing oximetry test for an infant?

Answer 16

<90% in initial/repeat screening either foot or right hand
90-94% in right hand and foot on 3 measures 1 hour apart
> 3% difference in 02 sat by right hand and either foot on 3 measures, 1 hour apart

Question 17

Where is pre ductal blood?

Answer 17

Right hand/arm

Question 18

Where is post ductal blood?

Answer 18

Lower extremities

Question 19

Normal temperature for a newborn?

Answer 19

Axillary= 36.5-37.5°C (97.7-99.5°F)

Question 20

Why are transient murmurs not uncommon in infants?

Answer 20

Not all of the ducts in the heart are fully closed yet

Question 21

How does an infant produce heat?

Answer 21

Nonshivering thermogenesis, increase in muscle activity/restlessness, peripheral vascular constriction

Question 22

Why is the breakdown of brown fat not ideal?

Answer 22

Consumes a lot of calories and oxygen

Question 23

What are the 4 methods of heat loss?

Answer 23

Conduction, convection, evaporation, radiation

Question 24

What is conduction?

Answer 24

Contact with cold objects

Question 25

What is convection?

Answer 25

Cold air draft

Question 26

What is evaporation?

Answer 26

Wet/moist skin dried by air resulting in cooling

Question 27

What is radiation?

Answer 27

No direct contact, transfer of heat to a cooler object

Question 28

What hormone is released to metabolize brown fat?

Answer 28

Norepinephrine

Question 29

How long do iron stores last?

Answer 29

4-6 months

Question 30

When does intestinal flora emerge in a newborn?

Answer 30

After 1st feeding

Question 31

What is the normal blood glucose range for an infant after 24 hours?

Answer 31

45-96 mg/dl

Question 32

When is vitamin K administered to infants? What does vitamin K do?

Answer 32

Administered within the 1st hour of life and it influences the activation of coagulation factors

Question 33

what is considered hypoglycemic for infants after 24 hours?

Answer 33

<40mg/dl

Question 34

What kind of cry does a hypoglycemic baby have?

Answer 34

Weak, high pitched

Question 35

What is seen in an infant with hyperbilirubinemia?

Answer 35

High levels of unconjugated bilrubin

Question 36

What causes jaundice?

Answer 36

Unconjugated bilirubin

Question 37

What is bilirubin?

Answer 37

Breakdown product of hemoglobin

Question 38

How is bilirubin transported and excreted?

Answer 38

Binds to albumin, transported to the liver and bound to intracellular proteins and conjugated ⇒ excreted in bile and carried to intestines ⇒ further broken down in intestine

Question 39

What is unconjugated bilirubin?

Answer 39

Indirect, lipid soluble, non-excretable. Crosses the blood brain barrier

Question 40

What is conjugated bilirubin?

Answer 40

Direct, water-soluble, excitable

Question 41

What kind of jaundice do most infants have 48-72 hours after birth?

Answer 41

Physiologic

Question 42

How long does physiologic jaundice typically last?

Answer 42

> 1 week in term infants, 2 weeks in premature infants

Question 43

When does pathologic jaundice occur?

Answer 43

Within 24 hours of birth

Question 44

What may cause pathologic jaundice?

Answer 44

Rh/ABO incompatibility, sequestered blood, breastfeeding or delayed feedings

Question 45

What does a positive directCoombs test on newborn blood indicate?

Answer 45

Hemolytic disease

Question 46

What does a positive indirect Coombs test on maternal blood indicate?

Answer 46

Anti- Rh antibodies

Question 47

What is the goal of jaundice treatment?

Answer 47

Kernicterus prevention

Question 48

What is phototherapy?

Answer 48

Rapid conversion of bilirubin to photobilrubin which does not require conjugation in the liver

Question 49

What can acute bilirubin encephalopathy lead to?

Answer 49

Kernicterus

Question 50

What % of term infants get jaundice? Preterm?

Answer 50

60%, 80%

Question 51

5 common screenings done on all newborns

Answer 51

Critical congenital heart disease, hyperbilirubinemia screening, glucose homeostasis screening, genetic disease screen, hearing screen

Question 52

Why are neonates prone to infection?

Answer 52

Their defense mechanisms are not fully mature

Question 53

What are some portals for bacterial entry on neonates?

Answer 53

Eyes, skin breakdown, and cord stump

Question 54

Which antibody is passed across the placenta passively during the last trimester of pregnancy?

Answer 54

IgG

Question 55

Which antibody is passed in the colostrum and is produced by newborns at 1 month?

Answer 55

IgA

Question 56

Which antibody is produced by the fetus in response to infection and does not cross the placenta?

Answer 56

IgM

Question 57

3 categories of neonatal infections

Answer 57

Acute life- threatening infection of the blood, localized infections, congenital infections

Question 58

What is considered vertical transmission?

Answer 58

Mother to infant: transplacental, ascending, intrapartum

Question 59

What is horizontal transmission?

Answer 59

From nursery personnel and hospital environment

Question 60

Signs of sepsis

Answer 60

Temp instability/hypothermia, respiratory distress, poor feeding/feeding intolerance, lethargy/irritability, persistent hypoglycemia

Question 61

Why can newborns dehydrate quickly?

Answer 61

Kidneys are immature

Question 62

Why does "brick-dust" urine occur?

Answer 62

Uric acid crystals in urine

Question 63

What does the Ballard maturational tool assess? What are the components of this assessment

Answer 63

Determines gestational age. 6 neuromuscular maturity assessments, 6 physical maturity assessments

Question 64

5 behavioral capacities of a newborn?

Answer 64

Habituation, orientation, self-quieting, motor maturity, social behaviors

Question 65

Where can newborns see the clearest?

Answer 65

8-12 inches from them, and they like to see bright colors

Question 66

Can newborns recognize voices?

Answer 66

Yes, especially maternal voice

Question 67

What smell do newborns respond to?

Answer 67

Breast milk

Question 68

What kind of taste does a newborn prefer?

Answer 68

Sweet tastes

Question 69

How often does an infant cry per day? When will the crying peak?

Answer 69

5 minutes to 2 hours per day. peaks at 2 months, then decreases

Question 70

What is another term for shaken baby syndrome? When does this most often occur?

Answer 70

Abusive head trauma. Most common at 2-4 months

Question 71

Who accounts for the majority of perpetrators for causing shaken baby syndrome?

Answer 71

Biological fathers ⇒ stepfathers ⇒ mothers' boyfriend ⇒ mothers