Gomez - Pediatric Lung Disorders Flashcards by Kash Kaul

What causes pulmonary hypoplasia?

Restriction of the fetus in utero

Deficiency of amniotic fluid

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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

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What embryonic structure do the lungs arise from?

Ventral wall of the foregut as lung buds

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How do congenital foregut cysts develop?

Remnant of foregut that should have regressed persists

Cyst fills with fluid and other material

Benign cysts

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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

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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

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What are congenital cystic adenomatoid malformations?

Hamartomatous lesions of abnormal bronchiolar tissue

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What is a Type I cystic adenomatoid malformation?

Large cysts

Good prognosis

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What is a Type II cystic adenomatoid malformation?

Small/medium sized cysts

Poor prognosis compared to Type I

Associated with other congenital malformations

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What are the two subtypes of bronchopulmonary sequestrations?

Extralobar

Intralobar

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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

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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

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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

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What is another name associated with neonatal respiratory distress syndrome?

Hyaline membrane disease

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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

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What is the major cause of neonatal respiratory distress syndrome?

Problem with surfactant production due to immature lungs

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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