Gomez - Pediatric Lung Disorders Flashcards
What causes pulmonary hypoplasia?
Restriction of the fetus in utero
Deficiency of amniotic fluid
What is the most common type of tracheoesophageal fistula? How will it present?
Blind ending pouch at the end of the upper esophagus
Lower esophagus communicates with distal trachea
Presents at feeding, where child will regurgitate everything
What embryonic structure do the lungs arise from?
Ventral wall of the foregut as lung buds
How do congenital foregut cysts develop?
Remnant of foregut that should have regressed persists
Cyst fills with fluid and other material
Benign cysts
What are the three types of foregut cysts?
Bronchogenic: lined by respiratory epithelium, sometimes with other respiratory structures (most common)
Esophageal: lined by squamous mucosa
Enteric: lined by intestinal mucosa
How do congenital cystic adenomatoid malformations appear?
Multiple cysts within thoracic cavity
Sometimes so numerous that they cause shifting of the mediastinum and heart
Shifting will result in atelectasis of lung tissue on that side and difficulty breathing
What are congenital cystic adenomatoid malformations?
Hamartomatous lesions of abnormal bronchiolar tissue
What is a Type I cystic adenomatoid malformation?
Large cysts
Good prognosis
What is a Type II cystic adenomatoid malformation?
Small/medium sized cysts
Poor prognosis compared to Type I
Associated with other congenital malformations
What are the two subtypes of bronchopulmonary sequestrations?
Extralobar
Intralobar
Describe extralobar bronchopulmonary sequestrations
Extra piece of lung tissue outside the lung itself
May be associated with other congenital malformations
No normal connection to airways
Blood supply is from systemic arteries, not pulmonary arteries
Describe intralobar bronchopulmonary sequestrations
Extra piece of lung tissue within the lobes of the lung
Associated with recurrent infection or bronchiectasis
Most likely acquired
Not connected to normal airways, so air can’t get in and mucus can’t get out, forming cyst-like structures
No normal connection to airways
Blood supply is from systemic arteries, not pulmonary arteries
What are some causes of respiratory distress in the newborn?
Hyaline membrane disease (most common)
Excessive maternal sedation
Fetal head injury
Aspiration of blood or amniotic fluid
Intrauterine hypoxia, i.e. from nuchal cord
What is another name associated with neonatal respiratory distress syndrome?
Hyaline membrane disease
What is the correlation between gestational age and rate of incidence of neonatal respiratory distress syndrome?
The incidence of the syndrome is inversely related with increased gestational age
i.e. the older the infant is at birth, the lower the incidence of the syndrome
What is the major cause of neonatal respiratory distress syndrome?
Problem with surfactant production due to immature lungs
Why is maternal diabetes correlated with neonatal respiratory distress syndrome?
Insulin inhibits the production of surfactant
Why is multiple gestation (twins, triplets, etc.) associated with neonatal respiratory distress syndrome?
Decreased intrauterine space from multiple fetuses causes potential constriction of lungs during development
What is the relationship between glucocorticoids and infant surfactant production?
Glucocorticoids induce production of surfactant
Release stimulated by stress response
Birth is a stressful event, so stimulates glucocorticoid release and therefore surfactant production
C-section birth associated with increased incidence of respiratory disorders, possibly because of lack of stress event of vaginal delivery
What stage of embryonic lung development is this? What gestational age does it correlate with?
Glandular stage
About 20 weeks
Very immature lung tissue, wouldn’t be able to tell which tissue without context
What stage of embryonic lung development is this? What gestational age does it correlate with?
Saccular stage
About 30 weeks
Begin to see structure of lung tissue
Alveoli still lined by cuboidal epithelium
Interstitium too thick, not good for gas exchange
What stage of embryonic lung development is this? What gestational age does it correlate with?
Alveolar stage
Full-term development
What cells produce/secrete surfactant?
Type II Pneumocytes
At what gestational age is surfactant production/secretion considered to reach “mature” levels?
35 weeks
What is the L/S ratio? What levels are significant?
Until surfactant production begins, lecithin and sphingomyelin produced at equal rates
When surfactant production begins, lecithin production increases significantly
L/S ratio in amniotic fluid < 1 indicates immature lungs
L/S ratio in amniotic > 2 indicates mature lungs
What is the gold standard method for detecting L/S ratio?
What is the drawback of this method?
What test is often used instead?
Thin layer chromatography (TLC) of amniotic fluid
Drawback: time consuming
Instead, foam stability index can be used
What is the progression of lung disease in infants delivered before lungs are mature enough to produce surfactant?
Low or absent levels of surfactant leads to atelectasis→causes uneven perfusion and hypoventilation→leads to CO2 retention and hypoxemia→causes acidosis→ultimately leads to lung damage and inflammation→leaky pulmonary capillaries allow plasma and proteins to accumulate in alveolar spaces→fibrin deposition and cellular necrosis lead to hyaline membrane disease
What disorder is shown in this image?
Hyaline membrane disease
What will the common clinical presentation of a newborn with respiratory distress syndrome look like?
Preterm birth
Low initial APGAR due to inability to breathe properly
May need resuscitation
May do well for a short time
Respiratory musculature will eventually tire out, and cyanosis will result
May hear crackles or rales from pulmonary edema
X-ray will show ground glass infiltrate/reticulonodular appearance
Why will you not see signs of respiratory distress syndrome in a stillborn?
No exudation of coagulation cascade proteins into alveolar spaces, infant must have been alive in order to see these changes
What can be done to treat neonatal respiratory distress syndrome?
Administer surfactant after birth
Administer glucocorticoids to mother prior to delivery
What are the criteria for bronchopulmonary dysplasia?
Infant older than 36 weeks post-menstrual age
On oxygen therapy for more than 28 days
What is bronchopulmonary dysplasia?
Neonatal lung development arrest in the saccular stage, i.e. failure of lung maturation
Leads to hypoplasia of alveoli and thickened walls, causing decreased efficiency of gas exchange
Can see dysmorphic capillaries due to decreased VEGF
What are the diagnostic criteria for cystic fibrosis?
One or more characteristic phenotypic features OR a history of CF in a sibling OR a positive newborn screening test result
AND
Increased sweat chloride concentration on two or more occasions OR identification of two CF mutations OR demonstration of abnormal epithelial nasal ion transport
The presence of what protein is used as a newborn screening test for CF?
Immunoreactive trypsinogen-pancreatic protein
Typically elevated in CF-affected infants
NOT DIAGNOSTIC for CF; if positive, must undergo further testing, but if negative then CF is unlikely
What is the classic test for cystic fibrosis?
Sweat chloride testing
Pts w/ CF will have elevated levels of ions in their sweat
When diagnosing CF by genetic mutation, what must you find?
Mutation in both CF genes; carrier state is not diagnostic
What pancreatic manifestations can be found in pts with CF? How are they treated?
Pancreatic insufficiency or diabetes mellitus (if Islet cells destroyed)
Treat insufficiency with oral Pancrelipase
Treat diabetes with insulin
What vitamin deficiencies occur with CF? How is this treated?
Problems absorbing fat soluble vitamins (ADEK)
These pts may require parenteral nutrition
What is the most invasive intervention for CF? Why must it be done?
Lung or heart-lung transplant
Necessitated by pts with severe cor pulmonale
