9-29 DSA - Pediatric Respiratory Pathology Flashcards
What are 2 intrauterine conditions that can lead to pulmonary hypoplasia?
low levels of amniotic fluid
restricted movement of the fetal chest wall
(basically anything that compress the lung or impede normal expansion in utero
What are the 3 types of tracheoesophageal fistula?
- blind ending pouch, esophagotracheal fistula for distal esophagus
- blind ending pouch, fibrous cord for distal esophagus
- communication of esophagus with trachea
What type of tracheoesophageal fistula is the most common?
blind-ending esophageal pouch with esophagotracheal fistula in distal part of esophagus
What type of tracheosophageal fistula causes the most respiratory complications?
communication of esophagus with trachea, aspiration pneumonia has a very high chance of developing
What is the embryological structure that congenital foregut cysts develop from?
the foregut
(if you get this wrong, go home. you’re probably drunk.)
How do congenital foregut cysts typically present?
mass or incidental finding, sometimes in adults
Where are congenital foregut cysts in the fully-developed person?
mediastinum or hilum
What is the general size and contents of congenital foregut cysts?
cyst spaces up to ~5 cm
contains bronchogenic tissue with respiratory epithelium
- filled with mucin, and one or more of:
cartilage
smooth mm
esophageal tissue - squamous mucosa
enteric tissue - intestinal mucosa
When are congenital foregut cysts problematic?
Considering hilar/mediastinal location, problems happen when they compress on other structures
- i.e. venal caval obstruction, jugular vein distension
Usually benign structures, rarely malignant
What is the histological description for a Congenital Cystic Adenomatoid Malformation?
hamartomatous lesion with abnormal bronchiolar tissue
(not a pulmonary hamartoma, which is made of proliferating lung tissue)
Which type of congenital cystic adenomatoid malformation has the worst outcomes? Why?
- Type I - large cysts, good prognosis
- Type II - medium cysts, poorer prognosis since associated with other congenital malformations
What is a bronchopulmonary sequestration?
area of lungs without normal connection to airways, with blood supply from systemic arteries
- no gas exchange due to lack of pulmonary circulation
What are the 2 types of bronchopulmonary sequestrations? Where are they located?
Extralobar: external to lung
(thorax or mediastinum)
Intralobar: within lung
What is associated with each type of bronchopulmonary sequestration?
Extralobar - may have other congenital anomalies
Intralobar - associated with recurrent local infection and/or bronchiectasis,
also most likely an acquired lesion
Extralobar bronchopulmonary sequestration is a congenital anomaly, and intralobar is an an acquired lesion. Why are the 2 types grouped together?
common findings - no viable blood connection to pulmonary circulation, only from systemic circulation
What is the most common cause of respiratory distress in the newborn?
- Hyaline membrane disease
- most common (24,000/year)
- 1,000 deaths/year in 2002
- 25,000 deaths/year in 1960’s
In addition to hyaline membrane disease, what are some other common causes of respiratory distress in neonates?
- Excessive maternal sedation
- Fetal head injury
- Blood or amniotic fluid aspiration
- Intrauterine hypoxia from nuchal cord
What is a nuchal cord? Why is it dangerous?
nuchal cord is when umbilical cord wraps around the neck of the fetus in utero
- true nuchal cord will leave indentations on the neck and trunk, and compress the neck enough to compress the large vessels of the neck, causing intrauterine hypoxia
What are the risk factors for neonatal respiratory distress syndrome/hyaline memb disease?
What are four other causes/associations?
preterm/age and normal weight
- Can occur in term infants, but most are preterm and have adequate growth for gestational age
- Rate inversely proportional to gestational age
- 60% < 28 wks, 30% 28-34 wks, < 5% >34 wks
Other causes:
- • Associated with male sex,
- maternal diabetes mellitus,
- multiple gestation
- C- section before onset of labor
Why is DM a risk factor for neonatal resp distress syndrome?
Mom has high levels of glucose, which crosses placenta and enters fetal circulation
fetus secretes lots of insulin
high levels of insulin inhibit surfactant secretion
What induces surfactant secretion?
glucocorticoids/stress (why c-sections are risk factor, less stress in baby in birthing process)
thyroxine
What physiological factors are associated with a higher risk for hyaline membrane disease?
- Immaturity of lungs!!
- Deficiency of pulmonary surfactant
- The first breath of life requires a large inspiratory effort but once inflated the lungs remain ~ 40% inflated
- If inadequate surfactant, lungs collapse back and every breath is as hard as the first
What are the important stages of lung development? What are the weeks when they happen?
20 weeks - glandular
30 weeks - saccular
term - alveolar
Describe the histological findings at each stage of lung development.
glandular - bronchioles and distal airspaces lined with cuboidal epithelium
frequent capillaries in loose CT in interstitium
Saccular - bronchioles still lined with cuboidal epithelium
alveolar ducts present
new alveoli lined with type I pneumocytes
rare type II pneumocytes
term - close to full developed, but thicker interstitium and increased diffusion barrier is present
What secretes surfactant?
Type II pneumocytes
When is there ‘mature’ levels of surfactant?
35 weeks
L/S ratio > 2 Lungs mature (except with some maternal diabetes)
< 1 Lungs are immature
How is L/S ratio measured? 4 methods
What is L/S?
Methods:
- Thin layer chromatography
- Flourescence polarization
- Foam stability index
- Lamellar body count
- Lecitithin/sphingomyelin ratio
What does surfactant consist of?
Consists of
Phospholipids
- Primarily dipalmitoyl phosphatidylcholine (lecithin)
- Also phosphatidylglycerol
Glycoproteins
- Hydrophylic SP-A & SP-D (immunity)
- Hydrophobic SP-B & SP-C (surface tension)
What happens with decreased pulmonary surfactant that leads to pulm edema in newborns?
increased alveolar surface tension
atelectasis
uneven perfusion& hypoventilation
hypoxemia & CO2 retention
acidosis
pulm vasoconstriction
pulm hypoperfusion
endothelial & epithelial damage
plasma leakage into alveoli
fibrin and necrotic cells (hyaline memb)
increased diffusion gradient
more hypoxemia and CO2 retention
What is the clinical presentation for respiratory distress syndrome in neonates?
- Preterm and AGA
- Male sex, maternal DM, C-section
- Low 1 minute Apgar score
- May need resuscitation
- Then may do well for short time (< 1 hour)
- Become cyanotic
- Fine pulmonary rales (crackles)
- Reticulonodular/ground glass chest x-ray
- Oxygen therapy needed
- Death or recovery in 3 – 4 days
Why does respiratory effort quickly cease in infants born without surfactant?
Lack of pulmonary surfactant leads to increased atelectasis, with increased work of breathing and inability to form residual capacity in lungs
MM of respiration eventually give out due to exhaustion
How is neonatal respiratory distress syndrome treated?
- Outlook much more favorable today
- Administration of surfactant (<28 weeks)
- Antenatal treatment with steroids (24-34 weeks)
- Monitor amniotic fluid surfactant for lung maturity
- Death now unusual
- Recovery begins at about 4 days
What are the risks associated with O2 therapy for neonatal respiratory distress syndrome?
- Retinopathy of prematurity
- Bronchopulmonary dysplasia
When is the bronchopulmonary dysplasia complication more common?
- > 28 days of O2 therapy in infant > 36 weeks post-menstrual age
- Now infrequent in infants >1200g and 30 weeks
Why have rates of bronchopulmonary dysplasia gone down?
•Gentler ventilation, steroids, and surfactant therapy reduced rates
Mild, moderate, or severe based on need for positive pressure O2 therapy
Why is bronchopulmonary dysplasia throught to happen?
- Alveolar hypoplasia & thickened walls
- O2 thought to inhibit lung maturation
- Dysmorphic capillaries and decreased VEGF
- Cytokines (TNF, Il-8, etc) increased and may have a role
What is cystic fibrosis?
- Widespread disorder in epithelial transport affecting fluid secretion in exocrine glands and the epithelial lining of the respiratory, gastrointestinal, and reproductive tracts
- Abnormally viscid mucus secretions
What are the genetic factors involved in CF?
- Autosomal recessive transmission
- Primarily due to abnormal function of an epithelial chloride channel protein encoded by the cystic fibrosis transmembrane conductance regulator (CFTR) gene on chromosome band 7q31.2
- Most common lethal genetic disease that affects Caucasians (1 in 2,500 live births in Caucasians)
- Estimate 5% of Caucasians heterozygous carriers (can also be symptomatic)
What is the diagnostic criteria for CF?
One or more characteristic phenotypic features
Or A history of cystic fibrosis in a sibling
Or A positive newborn screening test result (immunoreactive trypsinogen-pancreatic protein typically elevated in CF-affected infants)
And
An increased sweat chloride concentration on two or more occasions
Or Identification of two cystic fibrosis (CFTR) mutations
Or Demonstration of abnormal epithelial nasal ion transport (baseline nasal potential more negative than normal controls)
What complications need to be avoided with CF?
pancreatic insufficiency
vitamin deficiency
pulmonary disease
How is pancreatic insufficiency treated in CF patients?
•
- Oral Pancrelipase (lipase, protease, and amylase)
- May uncommonly need to treat diabetes mellitus if islets destroyed
How is vitamin deficiency treated in CF patients?
- Oral fat soluble vitamins (ADEK)
- Parenteral nutrition
How is pulmonary disease treated/avoided in CF patients?
looking for 9 here
- •Postural drainage and chest percussion
- •Bronchodilators (albuterol)
- •Mucolytic agents
- •Inhaled acetylcysteine to break down mucoproteins
- •Inhaled dornase alfa =Recombinant human DNase (rhDNase)
- •Antibiotics (need to cover Pseudomonus aeruginosa)
- •Hypertonic saline (inhaled)
- •High dose ibuprofen
- slows lung disease progression
- •Lung or heart-lung transplants
What is shown here?
How do you distinguish this in an adult vs. a kid?
Hyaline membrane disease
Distinguishable only by looking at the age of the patient apparently, per Gomez’s snark.
Wiggled Image: “Be able to recognize”
At what stage is the lung tissue shown here?
Alveolar
(didn’t wiggle, but we needed to be able to distinguish last year)
What stage of lung development?
Glandular
What stage of lung development?
Saccular
