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Flashcards in Acute Lung Injury Deck (20)
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What is the source of most pulmonary emboli?

deep veins of the leg and usually a complication of an underlying disorder such as immobilization or genetic hypercoaguability


The consequence of emboli depends on what?

the size of the embolus and the status of circulation- large size or inadequate circulation can result in infarction rarely


Emboli cause what kind of necrosis?



What happens to infarcted lung over time?

the tissue will start to organize and become paler due to conversion of hemorrhage to hemosiderin by macrophages and will eventually become a contracted star


Amniotic fluid emboli are characterized by what?

wavy purple keratin debris on microscopic appearance


What are some common causes of edema?

-liver disease (decreased oncotic pressure)
-infections, inhaled gases, shock


What happens in CHF?

The pulmonary vessels are engorged, the lungs are heavy and blood can be expressed from the cut surface and a foamy exudate can be seen.


What causes the pink substance in the alveoli in edema microscopically?

proteins in the exudate that have stained


What is the difference between passive and active congestion of the lungs?

active- inflammatory
passive-increased hydrostatic pressure


What is a hallmark of passive congestion of the lung?

hemosiderin-laden macrophages (brown) due to alveolar micro hemorrhages from the increase in pressure


What are some causes of ARDS?



How does ARDS present?

diffuse alveolar capillary damage with rapid, severe onset resulting in hypoxia and decreased ATP formation and associated with high death rate


What are the stages of ARDS?

-acute (exudative)
-organizing (proliferative)


What happens in the acute phase of ARDS?

endothelial injury leads to vascular leakage resulting in edema, then eosinophilic hyaline membrane formation, and even atelectasis


What happens in the organizing phase of ARDS?

type II pneumocyte proliferation and interstitial inflammation leads to organization and either recovery, interstitial fibrosis, or death


Are hyaline membranes common in the organizing stage of ARDS?

not so much anymore


Note about organizing phase

Hyaline membranes have been resorbed and replaced with plugs of idntraalveolar organizing fibroconnective tissue, which stain blue-green with a trichrome stain


What does the microscopic appearance of the acute phase of ARDS resemble?

Neonatal Pulmonary Disease (hyaline membrane appearance)


Deficiencies in both pulmonary surfactant and the fibrinolysis system are believed to be involved in what?

hyaline membrane disease


An autopsy of an elderly patient who expired in CHF shows a hemorrhagic pleural effusion and a peripheral wedge-shaped lesion in the right lower lobe. What is the most likely cause?

Pulmonary infarct