Pediatrics - Pyloric Stenosis & Neonatal Apnea

Question 1

What is the incidence of apnea of prematurity when the child is less than 30 weeks gestation?

Answer 1

80%

Question 2

What are some contributing factors to apnea of prematurity?

Answer 2

CNS disease, Systemic illness, thermal/metabolic disturbances, airway anomalies

Question 3

What are the 3 patterns of apnea?

Answer 3

Central: no airflow at nares and no muscular activity

Obstructive: muscular effort without nasal airflow

Mixed

Question 4

How is ventilation regulated?

Answer 4

Central rhythm (pattern) generator--root cause
Central chemoreceptors (CO2)
Peripheral chemoreceptors (O2)

Question 5

What are some possible causes of a less pronounced (flatter) CO2 response curve?

Answer 5

Prematurity
Flatter at 2 days than at 4 weeks postnatal age
Flatter in preterms with apnea than those without
Flatter during hypoxia

Question 6

What is the premature infants ventilatory response to hypoxia?

Answer 6

Initial increase followed by a sustained decrease

Question 7

At what age does the sustained increase ventilatory response mature?

Answer 7

At 1 week in term infants and about 3 weeks in preterm infants

Question 8

What enhances the initial increase in ventilation?

Answer 8

CO2

Question 9

What effects do halogenated anesthetics have on FRC and muscle tone?

Answer 9

Reduced FRC

Decreased muscle tone of airway, chest wall and diaphragm

Question 10

What effect do halogenated anesthetics have on the CO2 response curve?

Answer 10

Dose-dependent decrease in slope and right shift of CO2 response curve

Question 11

What effect do halogenated anesthetics have on the ventilatory response to hypoxia?

Answer 11

Depress ventilatory response to hypoxia (even at sub anesthetic doses)

Question 12

What is the post conceptual age?

Answer 12

Age since birth - weeks premature

Question 13

What type of pharmacological prophylaxis could potentially be used to help with AOP?

Answer 13

Caffeine (not routinely used, but helpfun)

Question 14

What are the recommendations for elective surgery for patients with AOP?

Answer 14

Delay elective surgery beyond 46 weeks post conceptual age

Question 15

At what age should infants be hospitalized and monitored with AOP?

Answer 15

<52 weeks PCA

Question 16

What type of emergency is pyloric stenosis?

Answer 16

Medical, not surgical

Question 17

Infants with pyloric stenosis should present to the operating room only after what has been normalized?

Answer 17

Adequate rehydration and normalized electrolytes

Question 18

Patients with pyloric stenosis are treated as at risk for what?

Answer 18

Aspiration

Question 19

What causes pyloric stenosis?

Answer 19

Hypertrophy of the muscularis layer of the pylorus

Question 20

What is the incidence of pyloric stenosis?

Answer 20

1: 300-500 live births
4: 1 male to female

Question 21

At what age does pyloric stenosis typically present?

Answer 21

2-6 weeks

Question 22

How does pyloric stenosis present?

Answer 22

Recurrent vomiting
Varying degree of malnutrition/dehydration
Palpable "olive" in the epigastrium
Visible peristalsis
Bradycardia
Jaundice (5-10% of cases)

Question 23

How is pyloric stenosis confirmed?

Answer 23

Barium swallow or ultrasound

Question 24

What are the three main anesthetic considerations for a patient with pyloric stenosis?

Answer 24

Aspiration risk
Dehydration
Metabolic derangements

Question 25

What are the physical findings for 5% dehydration?

Answer 25

Poor tissue turgor, dry mouth

Question 26

What are the physical findings for 10% dehydration?

Answer 26

Sunken fontanelle, tachycardia, oliguria

Question 27

What are the physical findings for 15% dehydration?

Answer 27

Sunken eyeballs, resting hypotension

Question 28

What are the physical findings for 20% dehydration?

Answer 28

Stupor, coma

Question 29

What are the two main serum electrolyte disturbances associated with pyloric stenosis?

Answer 29

Hypochloremic metabolic alkalosis | Hypokalemia

Question 30

What happens to urine as potassium and chloride stores are depleted?

Answer 30

Urine becomes more acidic

Question 31

What are some important considerations for preoperative management of patients with pyloric stenosis?

Answer 31

Acute volume repletion for shock Deficit replacement over 12-48 hours Establish normal urine output Normalize electrolytes

Question 32

What is the goal for normalizing chloride and bicarbonate pre operatively?

Answer 32

Cl > 90 | HCO3 < 30

Question 33

How is the procedure for pyloric stenosis usually performed?

Answer 33

Laparoscopically

Question 34

What are some important anesthetic management considerations for a pyloric stenosis operation?

Answer 34

Evacuate stomach by suction Pre-oxygenate and RSI or awake intubation Avoid narcotics Extubate awake