Cummings Pediatrics

Question 1

What is the balance of muscle fiber types in preterm infants that leads to high risk for respiratory fatigue?

Answer 1

More fast twitch (type II) than slow twitch (type I) fibers

Question 2

What is the most common sleep stage seen in infants?

Answer 2

REM (preterm babies spend 50-60% sleep in REM), intercostal musculature inhibited leading to increased fatigue of diaphragm

Question 3

How does euthermia vs hypothermic affect the ventilatory response to hypoxia in infants less than a week wold

Answer 3

Euthermia: biphasic response, tachypnea followed by hypoventilation
Hypothermia: hypoventilation

Question 4

What is the cause of periodic breathing seen up to age 6 (alternating rapid ventilation and apnea) when when does it become pathologic?

Answer 4

Dysregulation of feedback loops that control ventilation

Preterm infacnts, when apneic epicodes can last longer than 20 s and are accompanied by bradycardia

Question 5

What medication can be used to decreased apneic episodes in preterm infants

Answer 5

Aminopylline, via central stimulation

CPAP also an option

Question 6

What is the laryngeal chemoreflex (LCR)?

Answer 6

When laryngeal adduction is coupled with tachycardia, HTN, and apnea

Question 7

What is the avg total lung volume, TV, and dead space in infants

Answer 7

160 mL TLV
16 mL TV
5 mL DS (bc of small lung volume, any increase is more significant)

Question 8

Why do infants respond more quickly to inhaled anesthetic?

Answer 8

Higher alveolar ventilation and high resulting alveolar:functional residual capacity ratio

Question 9

At what age does the normal L>R venticular size ratio become established

Answer 9

By 6 months, initiated by closure of fetal circulation (R initially larger)

Question 10

What is the primary driver for cardiac output in infants?

Answer 10

HR 2/2 reduced contractility and compliance of infant heart

Question 11

Normal HR range for newborn

Answer 11

100-170

Question 12

What is most indicative of circulating blood volume in infants?

Answer 12

SBP–excellent guide for adequacy of blood or fluid replacement

Question 13

What is usually the first sign of hypoxemia in infants physiologically?

Answer 13

Bradycardia

Question 14

What are key characteristics of fetal hemoglobin?

Answer 14

Higher affinity for O2

Poor target tissue O2 delivery

Question 15

When does physiologic anemia cooresponding to fetal to adult hemoglobin conversion reach nadir?

Answer 15

2-3 mo (hgb 9-10), then should gradually rise to 12-13

Question 16

Calculation of maintenance fluids for peds

Answer 16

4 ml/kg/hr for the 1st 10 kg.
2 ml/kg/hr for the 2nd 10 kg.
1 ml/kg/hr for the remainder

Question 17

What is a dyssomnia

Answer 17

Sleep disorder characterized by an abnormality in the amount, quality, or timing of sleep that causes difficulty initiating or maintaining sleep

Question 18

What is a parasomnia

Answer 18

Undesirable event that occurs during entry into sleep or upon arousals

Question 19

What are the key features of narcolepsy?

Answer 19

Daytime somnolence
Cataplexy
Sleep onset paralysis
hypnagogic hallucinations