Pediatrics - Pyloric Stenosis & Neonatal Apnea Flashcards
What is the incidence of apnea of prematurity when the child is less than 30 weeks gestation?
80%
What are some contributing factors to apnea of prematurity?
CNS disease, Systemic illness, thermal/metabolic disturbances, airway anomalies
What are the 3 patterns of apnea?
Central: no airflow at nares and no muscular activity
Obstructive: muscular effort without nasal airflow
Mixed
How is ventilation regulated?
Central rhythm (pattern) generator--root cause Central chemoreceptors (CO2) Peripheral chemoreceptors (O2)
What are some possible causes of a less pronounced (flatter) CO2 response curve?
Prematurity
Flatter at 2 days than at 4 weeks postnatal age
Flatter in preterms with apnea than those without
Flatter during hypoxia
What is the premature infants ventilatory response to hypoxia?
Initial increase followed by a sustained decrease
At what age does the sustained increase ventilatory response mature?
At 1 week in term infants and about 3 weeks in preterm infants
What enhances the initial increase in ventilation?
CO2
What effects do halogenated anesthetics have on FRC and muscle tone?
Reduced FRC
Decreased muscle tone of airway, chest wall and diaphragm
What effect do halogenated anesthetics have on the CO2 response curve?
Dose-dependent decrease in slope and right shift of CO2 response curve
What effect do halogenated anesthetics have on the ventilatory response to hypoxia?
Depress ventilatory response to hypoxia (even at sub anesthetic doses)
What is the post conceptual age?
Age since birth - weeks premature
What type of pharmacological prophylaxis could potentially be used to help with AOP?
Caffeine (not routinely used, but helpfun)
What are the recommendations for elective surgery for patients with AOP?
Delay elective surgery beyond 46 weeks post conceptual age
At what age should infants be hospitalized and monitored with AOP?
<52 weeks PCA
What type of emergency is pyloric stenosis?
Medical, not surgical
Infants with pyloric stenosis should present to the operating room only after what has been normalized?
Adequate rehydration and normalized electrolytes
Patients with pyloric stenosis are treated as at risk for what?
Aspiration
What causes pyloric stenosis?
Hypertrophy of the muscularis layer of the pylorus
What is the incidence of pyloric stenosis?
1: 300-500 live births
4: 1 male to female
At what age does pyloric stenosis typically present?
2-6 weeks
How does pyloric stenosis present?
Recurrent vomiting Varying degree of malnutrition/dehydration Palpable "olive" in the epigastrium Visible peristalsis Bradycardia Jaundice (5-10% of cases)
How is pyloric stenosis confirmed?
Barium swallow or ultrasound
What are the three main anesthetic considerations for a patient with pyloric stenosis?
Aspiration risk
Dehydration
Metabolic derangements
What are the physical findings for 5% dehydration?
Poor tissue turgor, dry mouth
What are the physical findings for 10% dehydration?
Sunken fontanelle, tachycardia, oliguria
What are the physical findings for 15% dehydration?
Sunken eyeballs, resting hypotension
What are the physical findings for 20% dehydration?
Stupor, coma
What are the two main serum electrolyte disturbances associated with pyloric stenosis?
Hypochloremic metabolic alkalosis
Hypokalemia
What happens to urine as potassium and chloride stores are depleted?
Urine becomes more acidic
What are some important considerations for preoperative management of patients with pyloric stenosis?
Acute volume repletion for shock
Deficit replacement over 12-48 hours
Establish normal urine output
Normalize electrolytes
What is the goal for normalizing chloride and bicarbonate pre operatively?
Cl > 90
HCO3 < 30
How is the procedure for pyloric stenosis usually performed?
Laparoscopically
What are some important anesthetic management considerations for a pyloric stenosis operation?
Evacuate stomach by suction
Pre-oxygenate and RSI or awake intubation
Avoid narcotics
Extubate awake
