03b: ARDS Flashcards
Lung alveoli remain “water-free” via which mechanisms?
- Tight junctions in endothelial and ESP epithelial cell layers
- Lymphatic trainage
Starling equation depicts net force that drives water from lung (X) into (Y).
X = microvasculature Y = interstitial space
Pulmonary edema can occur via one of which mechanisms? Star the cause (if any) that preserves lung architecture.
- Permeability increased (non-cardiogenic)
2. Hydrostatic P increased (cardiogenic)*
T/F: It’s possible to tell if pulmonary edema is cardiogenic or non-cardiogenic by CXR.
True - check diaphragmatic angle (spared in non-cardiogenic)
Cardiogenic pulmonary edema: a result from (increase/decrease) in P of which heart chamber?
Increase;
LA
T/F: ARDS is a syndrome of chronic respiratory failure.
False - acute
List some clinical states associated with ARDS.
- Shock
- Infection
- Trauma
- Liquid aspiration
- Drugs
- Inhaled toxins
Pathogenesis of ARDS (epithelial injury): proposed pathway initiated by (intra/extra)-cellular (X), produced by (Y).
Extracellular
X = accumulation of oxidants
Y = cell surface NADPH oxidase complex in alveolar macrophages (in response to injury)
Pathogenesis of ARDS (epithelial injury): (extra/intra)-cellularly accumulated (X) target (Y), which act as endogenous ligands to (activate/suppress) (Z).
Extracellularly; X = oxidants Y = unsaturated phospholipids in surfactant Activate Z = TLR4 signaling on macrophage
Pathogenesis of ARDS (epithelial injury): Macrophage (X) signaling pathway is activated and induces which cytokine?
X = TLR4
IL-6 (amplifies acute inflammatory response)
T/F: Both severity and progression of ARDS are determined by magnitude of oxidative stress AND response of innate immune system.
True
T/F: Leukocytes were studied as mediators of final common pathway for ARDS, so severe ARDS unlikely to occur in neutropenic patients.
False - severe ARDS can still occur in the absence of leukocytes
T/F: Bottom line/end result of ARDS is overwhelming interstitial fibrosis and collagen deposition.
False - extensive damage to gas-exchanging surface
“Berlin” definition of ARDS looks at which 4 characteristics?
- Timing (insult in past week or new/worsening resp symtpoms)
- Imaging (bilateral opacities)
- Edema (not due to HF/volume overload)
- Oxygenation (PaO2/FiO2 ratio)
“Berlin” definition of ARDS: Mild, moderate, severe categories are established based on (X).
X = oxygenation (PaO2/FiO2 ratio)
Mild: 300-200
Mod: 200-100
Severe: under 100
Main goal of ARDS therapy:
Maintain gas exchange and hemodynamics until lung can repair itself (no drugs known to accelerate this recovery)
T/F: All supportive measures used in ARDS has potential to cause further injury.
True
In ARDS therapy, it’s crucial to assist (X) by mechanical ventilation and (Y).
X = work of breathing Y = PEEP (Positive End Expiratory Pressure)
How does PEEP work to assist (X) in ARDS?
X = work of breathing
Increases FRC (which increases compliance and opens/recruits collapsed lung units)
ARDS: Mechanical ventilation can involve “lung protective” strategy if (volume/pressure) cycled ventilator is used with (high/low) (X) volume.
Volume;
Low TV
Supplemental O2 alone (capable/incapalbe) of raising PaO2 in ARDS. Why?
Incapable;
Resistant hypoxemia is result of intra-alveolar shunting
T/F: PEEP in ARDS therapy is converting intra-alveolar shunt to V/Q mismatch.
True (one that responds to O2 therapy)
T/F: Trial found that lower (5 cm H2O) PEEP had better outcomes than higher (10 cm H2O) PEEP.
False - no difference in outcome;
So use less! Minimizes further risks of injury
ARDS maintenance/therapy: important to maintain oxygen delivery to tissues by measuring/monitoring which factors?
- CO (via urine output, mental status)
- Hgb (over 7 g/dL blood)
- SaO2 (over 90%)
ARDS maintenance/therapy: metabolic abnormalities should be corrected. This involves daily monitoring of…
- Electrolytes
- BUN, Creatinine
- Coagulation
- Glucose/nutrition
T/F: In ARDS, avoiding/treating infections includes prophylaxis.
False
Sepsis before ARDS likely originated from (X). Sepsis after ARDS likely originated from (Y).
X = abdomen Y = lungs (pneumonia)
T/F: Little evidence exists to support use of steroids in ARDS.
True - bad news outweigh good news
Using the Berlin Definition of ARDS, mortality is related to (X). How high is this mortality in mild/mod/severe ARDS?
X = severity of gas-exchange abnormality
20%, 41%, 52% respectively
T/F: Implementation of “lung protective strategy” for mechanical ventilation will not reduce overall mortality in severe ARDS.
False - reduces it, but mortality is still mainly related to severity of disease
T/F: Using Swan-Ganz catheter to assess volume status in ARDS patient will increase his/her risk for mortality.
True
Early death from ARDS is due to (X). Late death is due to (Y). Star the more common scenario.
X = Resp failure (catastrophic lung injury) Y = Sepsis/SIRS or MSOF (multi-system organ failure)***
T/F: Latest findings indicate that ARDS survivors have high prevalence of non-respiratory morbidity.
True
A history of (X) has been shown to increase incidence and mortality in ARDS.
X = alcoholism
Due to Cys, and thus glutathione (essential antioxidant), deficiency
