Pulmonary Pathology I Flashcards
In order for normal lung development, the infant must have:
Space within the thoracic cavity.
Ability to inhale.
- chest wall must be able to move.
- enough amniotic fluid must be around to inhale.
What is the progression of bronchus to alveolus during development? (6 steps)
Bronchus Terminal bronchiole Respiratory bronchiole Alveolar duct Alveolar sac Alveolus
Where do larger airways conduct air within the respiratory tree for gas exchange?
Terminal acinar units
What cells exist within the alveolar sac and septum?
RBCs
Type I and type II alveolar cells
Fibroblasts
Mo
Function of type I vs. type II pneumocytes cells
Type I - facilitates gas exchange
Type II - produce surfactant and replace type I pneumocytes
What is the function of alveolar pores (of Kohn)?
Allow aeration, but also bacteria/cells/exudate to travel between alveoli.
This allows aleoli to “share air” so they aren’t reliant only on their own aeration.
Pulmonary hypoplasia (3)
Reduced space within the thoracic cavity.
-diaphragmatic hernia, tumors, GI, etc. Anything that limits thoracic cavity space.
Impairment of ability to inhale.
- oligohydramnios (renal agenesis).
- airway malformation (tracheal stenosis).
- chest wall motion DOs.
High mortality (95%)
How does immediate death in the neonatal period occur in pulmonary hypoplasia?
If lung weight is <40%, immediate death occurs in neonatal period.
Foregut cysts (4)
Detached outpounchings of foregut seen along hilum and mediastinum.
Can be respiratory, esophageal, or gastroenteric.
Often incidental, complication include rupture, infection or airway compression. Mucous-filled.
Excision is curable.
Congenital pulmonary adenomatoid malformation (CPAM) occurs how?
Features: (4)
“Arrested development” of pulmonary tissue w/ formation of intrapulmonary cystic masses. There are 5 types depending on the stage of lung development.
Communicates w/ tracheobronchial tree.
Can be detected on fatal ultrasound.
Can be deadly due to hydrops or pulmonary hypoplasia.
Can become infected later in life.
Pulmonary sequestrations
Non-functioning lung tissue that forms as an aberrant accessory “lung bud”.
-usually in LLL.
Characterized by a lack of connection to the tracheobronchial tree AND an independent (systemic) arterial supply.
May be intralobar or extralobar, based on whether the budding occurs before or after the pleura is established.
Intralobar pulmonary sequestration (ILS) (2)
May present in older kids and adults.
Lack of airway perfusion makes these susceptible to infection and abscess formation.
Extralobar pulmonary sequestration (ELS) (3)
Usually presents after birth w/ other congenital abnormalities.
Independent vessels, *pleura, and possibly airways.
Become noticable as mass lesions in the chest or abdomen.
Which pulmonary seuestration (ILS/ELS) is associated w/ older kids/adults or at birth?
ILS as an older kid/adult, ELS as a newborn.
Which pulmonary seuestration (ILS/ELS) is associated w/ its individual pulmonary vasculature AND pleura?
ELS
Which pulmonary seuestration (ILS/ELS) is associated w/ tracheobronchial tree?
ELS
Resorption atelectasis
Airway obstruction w/ gradual resorption of air reduces lung expansion (apex lowers).
Compression atelectasis
Accumulated material in pleural cavity compresses lung parenchyma (base rises).
Contraction atelectasis
Fibrotic or other restrictive process in pleura or peripheral lung restricts expansion.
Where does fluid accumulate in pulmonary edema?
Interstitial fluid occurs in alveolar spaces.
3 causes of pulmonary edema from “pushing out”
LSHF
Volume overload
Pulmonary v. obstruction
3 causes of pulmonary edema from “leaking out”
Hypoalbuminemia
Nephrotic syndrome
Liver Dz
4 causes of pulmonary edema from injury to alveolar wall
Bacterial pneumonia
Sepsis
Smoke inhalation
Aspiration
What 2 other processes can cause pulmonary edema via an unknown mechanism?
Neurogenic (brain injury)
High altitude
High altitude pulmonary edema (HAPE) leads to accumulation of what substance in the alveolar spaces?
A pink proteinaceous material.
Which 2 diseases exist within the ARDS spectrum?
Acute lung injury (ALI)
ARDS
Acute lung injury (ALI) SX
Level of hypoxemia:
Acute onset, hypoxemia and BL infiltrates.
No evidence of cardiac failure.
< 300 PaO2/FiO2
ARDS onset:
Level of hypoxemia:
On CXR:
Cardiac involvement?
Abrupt onset.
<200 PaO2/FiO2
BL infiltrates on CXR.
Non-cardiac in nature.
4 “steps” of development ARDS
- Endothelial activation
- Adhesion/extravasation of neutrophils
- Accumulation of intraalveolar fluid and formation of hyaline membranes
- Resolution of injury
Diffuse alveolar damage (DAD) leads to _____.
How?
Hyaline membranes.
Edema + fibrin + cell debris accumulation.
Ventilation-perfusion mismatch in hyaline membranes
The membranes are damaged -> decreased aeration -> ventilation-perfusion mismatch (decreased PaO2/FiO2)