deck_5326617 Flashcards
How can ARDS be defined?
respiratory distress with stiff lungs (i.e. decreased compliance) and diffuse alveolar damage with ACUTE onset
How would ARDS present upon chest radiograph?
new bilateral, diffuse, patchy or homogeneous pulmonary infiltrates
How would ARDS present upon cardiac exam?
no apparent cardiogenic cause of pulmonary edema (exudate is protein rich due to increase vascular permeability)
How would mild ARDS present upon exam of PaO2/fractional inspired oxygen ratio?
less than 300 mmHg
How would moderate ARDS present upon exam of PaO2/fractional inspired oxygen ratio?
less than 200 mmHg (severe is less than 100)
What is the most common pre-disposing factor that leads to ALI/ARDS?
sepsis (20-40% of sepsis patients will develop sepsis)
T or F. Acute lung injury can be viewed as an early manifestation of a generalized inflammatory response with endothelial dysfunction and is therefore frequently associated with the development of multiple organ dysfunction syndrome (MODS)
T. Predisone helps
What is the cardinal feature of ALI?
non-cardiogenic pulmonary edema
Why does non-cardiogenic pulmonary edema occur in ALI?
generalized increase in vascular permeability caused by the microcirculatory changes and release of inflammatory mediators ANDThe pulmonary epithelium is also damaged in the early stages, reducing surfactant production and lowering the threshold for alveolar flooding.
What is another common feature of ALI/ARDS?
pulmonary HTN
Why does pulmonary HTN occur?
1) mechanical compression due to edema 2) local activation of micro-clots3) hypoxic vasoconstriction in response to decreased diffusion
Describe the intra-alveolar exudate seen in ALI/ARDS?
it is rich in platelets, fibrin, and fibrinogen/CFs
How can the exudate affect the lungs?
-may inactivate surfactant and stimulate inflammation-promotes migration of fibroblasts into the air spaces
What are some of the side-effects of lung tissue repair following injury?
interstitial fibrosis progresses, with loss of elastic tissue and damage to vasculature, couple with emphysema
What are some physiologic changes that accompany ALI/ARDS?
-shunt and dead-space increase-compliance decreases-diffusion limitations increase
What is the first sign of ALI?
unexplained tachypnea, followed by hypoxemia
Other signs of ALI?
fine crackles in both lung fields
What is an air bronchogram?
A tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammatory exudates.
Chest radiograph developments in ALI?
-bilateral diffuse shadowing-eventually air bronchograms-no cardiac enlargement
What is on the DDX of ALI?
-Cardiac failure-lung fibrosis