Adaptations of Newborn

Question 1

Name 2 reasons that there is high pulmonary pressure in utero

Answer 1

1. Lungs are fluid-filled
2. Pulmonary vessels are vasoconstricted

Question 2

How does systemic and pulmonary vascular resistance change at birth?

Which shunts close?

Answer 2

• Increased systemic vascular resistance
• Decreased pulmonary vascular resistance
• Closure of R->L shunts

Question 3

Why are fetuses not considered viable before 26 weeks?

Answer 3

Alveolar sacs begin to grow at this time

Question 4

What is the function of surfactant?

How does it affect compliance?

What is it made of?

Answer 4

• Decreases surface tension and prevents alveolar collapse
• Increases compliance
• Made of phospholipids (phosphatidylcholine)

Question 5

Compare what happens normally after a full exhale and what happens if there’s surfactant deficiency.

Answer 5

• Normal: lungs do not collapse completely with exhale
• Surfactant def: lungs collapse completely with exhale due to decreased compliance and increased surface tension

Question 6

A premature baby exhibits grunting, retraction, and flaring.

What is the problem?

Why are they grunting?

What would you expect of CXR?

Answer 6

• Surfactant deficiency
• Grunting increases the positive end expiratory pressure to prevent alveolar collapse
• CXR = whiteout

Question 7

What is one component to amniotic fluid besides fetal urine?

What happens to all this fluid at birth?

Answer 7

• Lungs produce fluid that contributes to amniotic fluid
• This must all be resorbed at birth

Question 8

What is the mechanism by which the alveoli absorb fluid at birth?

Answer 8

Cortisol activation of ENac channels -> fluid pulled into interstitium -> fluid drained by lymphatics

Question 9

What babies typically present with retained pulmonary fluid?

Answer 9

Mature C-section babies

Question 10

What are the components of an APGAR score?

Answer 10

Appearance (pink, mixed, blue)

Pulse (over 100, under 100, no pulse)

Grimace

Activity

Respirations (strong cry, weak cry, no cry)

Question 11

Name 2 reasons the ductus arteriosus closes at birth.

Answer 11

Decreased pulmonary resistance

Increased PaO2

Question 12

What causes the foramen ovale to close?

Answer 12

Increased LA pressure and decreased RA pressure

Question 13

Compare the route of blood supplying the head and blood supplying the body

Answer 13

• Blood supplying the head
  
  • RA -> foramen ovale -> LA -> LV -> aorta -> large vessels
• Blood supplying body
  
  • Blood from above pathway plus…
  • RA -> RV -> Pulmonic trunk -> ductus arteriosus -> thoracic aorta

Question 14

Which ventricle is dominant in utero?

Answer 14

RV

(b/c PVR is very high and SVR is very low)

Question 15

Define Persistent Pulmonary HTN of Newborn

What is the (broad) source of this problem?

Answer 15

PVR remains high

Due to lung disease

Question 16

What is one immediate complication with infants of diabetic mothers?

Why?

Answer 16

Hypoglycemia

Baby is making high insulin in utero in response to high maternal glucose levels

Birth -> loss of constant glucose infusion from placenta, but it takes time before baby’s insulin levels decrease

Question 17

What is the problem in an infant who is jittery at 1 hour?

What if jittery at 1 day?

Answer 17

Jittery at 1 hr = hypoglycemia

Jittery at 1 day = hypocalcemia