Newborn Transition

Question 1

What are the structures of the upper respiratory tract?

Answer 1

1) nose
2) nasal cavity
3) sinuses
4) larynx
5) trachea

Question 2

What are the structures of the lower respiratory tract?

Answer 2

1) lungs
2) bronchi and bronchioles
3) alveoli

Question 3

Fetal pulmonary circulation has (high/low) vascular resistance

Answer 3

high

lungs are closed, fluid-filled w/ minimal blood flow

Question 4

What occurs during the canalicular stage?

Answer 4

@16-24wks GA

• terminal alveolar sacs appear

Question 5

What occurs during the saccular stage?

Answer 5

@28-34wks GA

• capillaries come into contact with alveolar basement membrane
• primitive alveoli develop and are lined w/ 2 types of alveoli cells
  1) type 1 = thin epithelial alveolar cells = gas exchange
  2) type 2 = cuboidal epithelial cells = surfactant production and storage

Question 6

What occurs during the alveolar period?

Answer 6

@36wks GA through childhood

• more alveoli form –> larger surface area for gas exchange
• 1/3 of alveoli mature at birth; rest mature after

Question 7

What happens to the fluid in fetal lungs?

Answer 7

begins to clear a few days before labor

Question 8

Fetal Hgb has (higher/lower) affinity for O2.

Answer 8

higher

• facilitates O2 transport across placenta
• may result in 80% O2 saturation

Question 9

How is respiration initiated in the NB?

Answer 9

1) fetal plasma levels of catecholamines and cortisol increase during labor
2) stimulates reabsorption of lung fluid (vs secretion before)

Question 10

What effect does the first active breath have?

Answer 10

1) assists w/ conversion from fetal to adult circulation
2) further empties lungs of fluid
3) establishes neonatal lung volume and characteristics of pulmonary function
4) decreases pulmonary artery pressure

Question 11

At which gestational age is there sufficient surfactant?

Answer 11

34wks

Question 12

What is the function of surfactant?

Answer 12

• reduces surface tension at air/liquid interface in alveoli
• stabilizes alveolar walls so they don’t collapse at end of each breath

Question 13

What stimulates release of surfactant?

Answer 13

lung expansion

Question 14

Define functional residual capacity

Answer 14

gas volume left in lungs at end of each expiration

Question 15

What helps maintain functional residual capacity in a NB?

Answer 15

• crying –> slower expiration

- diaphragm

Question 16

What keeps the ductus arteriosus open?

Answer 16

1) placental prostaglandin
2) prostacyclin
3) low O2 tension

Question 17

What occurs at birth to the ductus arteriosus?

Answer 17

constriction!

• blood from R ventricle enters pulmonary circulation
• facilitated by oxygenated blood that otherwise flowed past it

Question 18

When does the ductus arteriosus close?

Answer 18

w/in 48h

Question 19

What is the effect of cord clamping on NB circulation?

Answer 19

• stops low pressure fetal-placental circulation –> NB circulation = closed system

+ first breaths –> decreased pulmonary vascular resistance + increased systemic vascular resistance –> blood flow to pulmonary system

Question 20

Which substances facilitate vasodilation?

Answer 20

1) prostacyclins
2) nitric oxide
3) O2

Question 21

What lowers pulmonary vascular resistance in the NB?

Answer 21

1) physical lung expansion
2) release of prostacyclins and nitric oxide
3) increased O2 tension

Question 22

What stimulates release of prostacyclins and nitric oxide?

Answer 22

1) shearing forces on endothelium w/ increased pulmonary blood flow
2) artery distention –> bradykinin release –> prostacyclin and NO release

Question 23

Define asphyxia

Answer 23

state of extreme O2 deficiency and CO2 excess

Question 24

What are the consequences of asphyxia?

Answer 24

1) metabolic acidosis

2) signs of organ failure

Question 25

What are various issues that can exacerbate asphyxia and result in respiratory depression in the NB?

Answer 25

1) acute interruption of umbilical blood flow (e.g. cord compression) 2) premature placental separation 3) maternal hypotension or hypoxia 4) the above superimposed on chronic uteroplacental insufficiency 5) failure to execute proper resuscitation 6) maternal use of anesthetics/analgesics 7) mode and difficulty of delivery 8) maternal health 9) prematurity

Question 26

Define ductus venosus

Answer 26

shunts blood from umbilical vein to inferior vena cava --> allows blood to bypass fetal liver

Question 27

Define ductus arteriosus

Answer 27

shunts blood from pulmonary artery to descending aorta --> allows oxygenated blood to bypass fetal lungs

Question 28

Define foramen ovale

Answer 28

shunts blood from right to left atria--> allows blood to bypass fetal lungs

Question 29

Define umbilical artery

Answer 29

2 arteries in cord --> deoxygenated blood from fetus to placenta

Question 30

Define umbilical vein

Answer 30

carries oxygenated blood from placenta to fetus

Question 31

What causes the ductus venosus to close?

Answer 31

lack of blood return from placenta

Question 32

What causes the foramen ovale to close?

Answer 32

increased pulmonary blood flow --> increased venous return to L atrium --> increased L atrial pressure --> stents foramen ovale closed

Question 33

When should the foramen ovale close?

Answer 33

soon after birth

Question 34

What are NB sources of heat?

Answer 34

1) non-shivering thermogenesis = primary method 2) oxidative glucose, fat, and protein metabolism 3) voluntary muscle activity 4) shivering

Question 35

Describe non-shivering thermogenesis

Answer 35

- birth = cold --> triggers hypothalamus to oxidize stored lipids in brown fat --> heat production - warms blood before circulating to peripheral areas - in NBs w/ hypoglycemia or thyroid dysfunction --> ineffective use of brown fat

Question 36

What is a normal NB axillary temp?

Answer 36

36. 5 - 37.5 C | 97. 5 - 99.3 F

Question 37

What are the 4 mechanisms of heat loss?

Answer 37

1) convection = transfer of heat through air 2) conduction = transfer of heat to cooler surfaces 3) radiation = transfer of heat via thermal waves to cooler surfaces not in direct contact 4) evaporation = loss of heat from evaporation of moisture

Question 38

How should NB temperature be maintained?

Answer 38

1) skin-to-skin = best! 2) drying, bundling 3) warmer 4) postpone first bath 5) cute lil' hat!

Question 39

What factors predispose the NB to hypothermia?

Answer 39

1) large surface 2) limited subQ fat insulation 3) limited ability to generate heat via shivering 4) immature permeable skin 5) wet w/ amniotic fluid

Question 40

What are s/sx of NB issues w/ thermogenesis?

Answer 40

1) low core temp + cold skin 2) pale skin, pallor 3) hypotonia 4) lethargy, irritability 5) poor feeding 6) vomiting 7) tachypnea 8) increased HR 9) shivering = severe cold stress

Question 41

Describe how hypothermia can result in hypoglycemia

Answer 41

increased metabolic rate --> increased use of glucose --> hypoglycemia

Question 42

Describe how hypothermia can result in respiratory distress/hypoxia

Answer 42

hypoglycemia --> decreased surfactant production --> respiratory distress inc O2 consumption --> anaerobic metabolism --> lactic acid production --> metabolic acidosis --> decreased surfactant production --> respiratory distress

Question 43

Describe how hypothermia can result in metabolic acidosis

Answer 43

brown adipose tissue metabolism --> anaerobic metabolism --> lactic acid production --> metabolic acidosis

Question 44

What 4 systems undergo the greatest change during the transition from intra to extrauterine life?

Answer 44

1) respiratory 2) circulatory 3) thermoregulatory 4) glucose metabolism

Question 45

Upon what are circulatory changes in the NB dependent?

Answer 45

respiratory transition and oxygenation

Question 46

What are low thresholds for NB glucose levels?

Answer 46

1-2h: 28 mg/dL 3-23h: 40 mg/dL 24-47h: 41 mg/dL 48-72h: 48 mg/dL

Question 47

How are the three ways in which NBs receive glucose?

Answer 47

1) breastmilk/formula 2) glycogenolysis = breakdown of fetal glycogen stores in liver 3) gluconeogenesis

Question 48

What are the benefits of vernix?

Answer 48

Antimicrobial proteins and peptides... 1) moisturizes skin 2) keeps skin acidic --> inhibits growth of pathogens

Question 49

How much glucose do NBs need?

Answer 49

4-8 mg/kg/min

Question 50

What are s/sx of hypoglycemia in the NB?

Answer 50

1) jitteriness 2) irritability 3) lethargy 4) poor feeding

Question 51

What NB blood glucose level requires further intervention?

Answer 51

<45-50 mg/dL confirm w/ venous sample and inform pediatric provider

Question 52

Define APGAR

Answer 52

0, 1, or 2 pts ``` Appearance (skin color) Pulse Grimace (reflex irritability) Activity (tone) Respiration ``` ``` 7-10 = vigorous 4-6 = some resuscitation needed <3 = intense resuscitation needed ```

Question 53

When does the NB no longer experience the Moro reflex?

Answer 53

2-4 months