18. Pulmonary Path 1 Flashcards
Threre are 5 stages of normal fetal lung development, starting with the embyronic lung bud, and what are the final 4 stages?
Pseudoglandular
Canalicular
Saccular
Alveolar
In the alveolar stage is where terminal buds grow, what can one determine via the stage of lung development?
Age of the fetus
There are important requirements for normal lung development including adequate space in the thoracic cavity and the ability to?
INHALE
chest wall must be able to move and there must be enough amniotic fluid present
Larger airways conduct air to the terminal acinal units for proper?
gas exchange
The trachea and bronchus are rigidly open and patent and end at respiratory bronchioles which have thin walls with high vascularity for?
gas exchange to occur
The trachea histologically consists of cartilage, a submucosa, a smooth muscle layer, a lamina propria, and respiratory epithelium which contains? 4
Pseudostratified ciliated epithlium which contains:
Goblet (mucous cells)
Cilia
Ciliated columnar cells
(*all to keep the airways open and clean)
The lung parenchyma (functioning part) contains bronchioles, blood vessels, and most importantly, abundant?
Alveoli (white space where gas exchange occurs)
Histologically, lung parenchyma consists of erythrocytes which are extremely red/hot pink/purple within capillaries. Also type 1 and 2 pneumocytes can be seen. What distance needs to be minimal?
The distance between capillaries and alveolar in order to allow for quick gas exchange (takes less than 1s to dump CO and pick up O2)
In alveolar structure, there are capillaries with endothelium and a basement membrane with interstitium. What are the main jobs of Type 1 and 2 Pneumocytes?
Type 1: cover 95% of alveoli and facilitate gas exchange (flattened plate like)
Type 2: Produce surfactant and replace type 1 (stem cell action) when needed
What in the lung alveoli allow aeration (redundant) but also allow bacterial, cells and exudate to travel between alveoli?
Alveolar pores of Kohn
What congenital abnormality causes 1/2 of mortality in babies?
Pulmonary hypoplasia
Pulmonary hypoplasia can be caused by reduced space in the thoracic cavity (diaphragmatic hernia/tumors) or by the impaired ability to inhale via what 3 mechanisms?
Chest wall motion disorders
Airway malformations (tracheal stenosis)
Oligohydramnios
Oligohydramnios can be caused by renal agenesis as seen in Potters sequence, what occurs during this?
there is renal agenesis which causes a lack of fetal urine leading to lack of amniotic fluid and lung hypoplasia
A fetal lung should be at the same level of the bottom of the heart, there is high mortality (up to 95%); if the lung weight is less than 40% what occurs in the neonatal period?
immediate death
What arise from an abnormal detachment of primitive forgut and are most often located in the hilum or middle mediastinum (bronchogenic-MC)?
Foregut cysts
Foregut cysts can be respiratory, esophageal or gastroenteric and are often seen incidentally, 3 of the complications include?
Rupture
Infection
*Airway compression
Excision for foregut cysts is curative. What is the classification for the cysts, which has a single ‘balloon’ wall, with not other cysts, but fluid inside?
Foregut cysts are classified as SIMPLE cysts
Congenitla pulomanary (cystic) adenomatoid malformation (CPAM/CCAM) is known as arrested development of pulmonary tissue with formation of?
intrapulomnary cycstic masses
CPAM communicated with the tracheobronchial tree and can be detected on fetal U/S. It can be deadly due to hydrops or pulmonary hypoplasia and can get?
infected later in life (or incidentally found)
CPAMs should be taken out during gestation (in utero) because it competes for?
normal thoracic space, causing lung hypoplasia
What are nonfunctioning lung tissue that forms as an abberant accessory “lung bud”?
Pulmonary sequestrations
Pulmonary sequestations are typically in the left lower lobe (so both R/L lungs have 3 lobes), they are characterized by a lack of any connection to the airway system and an independent?
arterial supply from the aorta or its branches
Pulmonary sequestrations may be intralobar or extralobar depending on whether budding occurs before or after?
pleura is established
What type of sequestration lacks airway perfusion, does not have its own pleura, making them susceptible to infection and abcess formation?
Intralobar pulmonary sequestrations ILS
seen in older children and adults with recurrent location infection or bronchiectasis
Extralobar pulmonary sequestrations (ELS) usually presents after birth with other congenital malformations (heart). They have independent vessles and (sometimes airways), and come to attention as mass lesions in the chest. What is the main difference between ELS and ILS
ELS has its own pleura while ILS does not!
What is the main difference between the lesions in CPAM and pulmonary sequestrations?
CPAMs are within the lung connected to tracheobronchial airways and pulmonary vasculature which sequstrations have NO connection to pulmonary vasc or trach tree (usually only have independent vessels off aorta)
Acquired atelectasis (collapse) refers to incomplete expansion of the lungs (neonatal) or to the collapse of previously inflated lung, producing areas of relatively airless pulmonary parenchyma, seen in?
Adults
What occurs due to complete airway obstruction with graudal resorption of air, reducing lung expansion/causing collapse?
Resorption Atelectasis
Resorption atelectasis is commonly due to excessive secretions or exudates within small bronchi, what occurs anatomically in resorption atelectasis?
mediastinum shifts towards the affected lung b/c lung volume is diminished
What tpy eof atelectasis is not related to the lung, and is due to accumulated material in the pleural cavity compressing the lung parynchema?
Compression atelectasis
Compression atelectasis occurs when volumes accumulate such as transudate, exudate blood or air, causing the mediastinum to shift?
away from the affected lung (opposite resorption atelectasis)
What is the most common type of acquired atelectasis which is due to fibrotic or other innate restrictive processes in the pleura or peripheral lung, restricting lung expansion?
Contraction atelectasis (mediastinal shift toward affected lung)
What is pink material (interstitial fluid) in alveolar spaves which decreases aeration and gas exchange?
Pulmonary edema
Pulmonary edema is caused by many influences. Physiologically, what are the two main ways edema occur?
Increased hydrostatic pressure = forces fluid out (result of L heart failure)
Decreased oncotic pressure (hypoalbuminemia) = loses fluid through equilibrium across a semipermeable membrane
Pulmonary edema causes heavy, wet lungs, leading to decreased oxygenation because the diffusion barrier is increased. Leads to granular pink proteinaceous material in alveolar spaces initially, chronically leads to brown firm lungs due to interstitial fibrosis and ?
hemosiderin laden macrophages (heart failure cells)
Pulm edema is also caused by microvascular (alveolar) injury, including bacterial pneumonia, sepsis, smoke inhalation and?
aspiration (near drowning)
What can also cause pulmonary and cerebral edema causing death extremely quick?
High altitude pulmonary edema (HAPE)
What is characterized by abrupt onset of significant hypoxemia and bilateral pulmonary infilitrates in the absence of cardiac failure?
Acute lung injury ALI
What is the manifestation of worsening hypoxemia, or severe ALI?
Acute Respiratory distress syndrome ARDS
What is known as the histological manifestation of ALI/ARDS, which are both associated with inflammation associated increases in pulmonary vascular permeability, edema and epithelial cell death?
Diffuse Alverolar Damage (DAD)
ARDS has an abrupt onset of symptoms (infection, physical injury, inhaled irritants, chemical injury, hematologic conditions). Hypoxemia is important, what PaO2/FiO2 is needed to be considered ARDS?
PaO2 (amount of blood in circulation) FiO2 (fraction of O2 being breathed in) = arterial blood gas is less than or equal to 200 (ALI requires less than 300)
Along with a PaO2/FiO2 of less than 200, ARDS is non cardiac in nature and or not secondary to a heart condition and often will see what on CXR?
cloud CXR with bilateral infiltrates
ARDS can result from insults from the respiratory system or from circulation. Increased alveolar capillary permeability cause fluid leak and alveolar damage. What biochemically causes the inc. permeability?
Disrupted VE-cadherin bonds
ALI/ARDS is initiated by injury of pneumocytes and pulm endothelium causing an increasing cylce of inflammation and pulmonary damage. What is the first stage?
Endothelial activation
Endothelial activation occurs when there is a respiratory or systemic (sepsis) insult to pneumocytes sense by resident macrophages. What happens next, after endothelial activation?
Neutrophilic adhesion and extravastion, releasing mediators such as PAF, leukotriences and proteases to recruit more
After neutrophilic extravasion, accumulation of intralaveolar fluid occurs, damaging type 2 pneumocytes causing surfactant related issues. The protein rich fluid and dead epithelial cells forms? (characteristic of ALI/ ARDS)
hyaline membranes
After formation of hyaline membranes, resolution of injury occurs if inflammation lessens and macrophages and clean everything up with fibrogenic factors such as? (2)
TGFB
PDGF
In acute ARDS, lungs are heavy, firm, red and boggy and exhibit congestion, edema, inflammation, fibirin deposition and?
Diffuse aveolar damage
Alveolar hyaline membranes consist of fibrin-rich edema fluid mixed with cytoplasmic and lipid remnants of necrotic epithelial cells (protein rich exudate). Usually granulation tissue resolves post injury, but sometimes there is fibrotic?
thickening of alveolar septa
Edema + fibrin + cell debris =?
Hyaline membranes
When there are hyaline membranes which thicken the diffusion distance between capillaries and alveoli, there is decreased aeration causing ventilation?
perfusion mismatch =(decreased PaO2/FiO2)
ARDs has multiple stages: 1) exudative - edema. hylaline membranes, neutrophils. 2) proliferative: fibroblast proliferation, organizing pneumonia, early fibrosis 3) fibrotic: extensive fibrosis, loss of normal alveolar structure. Which stage do 40% of people with ARDS die?
The exudative stage
After fibroproliferative phase, 2 pathways may result: 1) resolution, type 2 pneumocytes restore and normal cellular struction/fucntion 2) fibrosis causing distruction/distortion of cell structure which does what to the alveoli?
Shrinks the alveoli (fibrosis)
Clinically ALI/ARDS present cyanosis, hypoxemia, respiratory failure, and the appearance of diffure bilateral infiltrates. What two sx are characteristic of ARDS/ALI?
Dyspnea
Tachypnea
To clinically diagnose ARDS is must be acute onset, bilateral infiltrates, hypoxemia and exlusion of heart failure. Pathologic diagnosis via hyaline membranes, interstitial edema and epithelial necrosis. What is the main difference between ARDS and acute interstitial pneumonia (AIP)?
AIP has same clinical and histological presentation except it CANNOT be attributed to a specific etiology (idiopathic)
What lung disease is characterized by an increase in resistance to airflow due to partial or complete obstruction at any level from the trachea and larger bronchi to the terminal and respiratory bronchioles?
Obstructive lung diseases