Small Group ARDS and Respiratory Failure Flashcards
What is common about the major causes of ARDS?
the causes do damage to the alveolar capillaries throughout the lung
What is the pathogenesis of hyaline membrane formations in ARDS?
alveolar lining cells are damaged and fibrin-rich fluid mixed with cytoplasmic and lipid remnants of necrotic epithelial cells accumulates in the alveolar space, forming alveolar hyaline
“Complete” resolution of ARDS requires what processes?
removal of exudates and tissue debris by macrophages
epithelial cells are recovered by proliferation of surfing type II pneumocytes (bronchoalveolar stem cells may also participate)
endothelial restoration occurs both by migration from uninjured capillaries and marrow-derived endothelial progenitor cells
A patient suffering from ARDS has a low PaO2 despite being on substantial supplemental oxygen. What is the likely cause of their hypoxia?
right to left stunt, presumably intrapulmonary
What are two common causes of metabolic acidosis in traumatic injury, ie. car crash serious injury.
lactic acidosis caused by a hypo-perfused state or hyperchloremic acidosis which could be differentiated by a measurement of anion gap or lactate levels
What is mean airway pressure and what is it used to measure?
Mean airway pressure typically refers to the mean pressure applied during positive-pressure mechanical ventilation. Mean airway pressure correlates with alveolar ventilation, arterial oxygenation, hemodynamic performance, and barotrauma.
What situations would cause a high mean airway pressure in someone that is on positive pressure ventilation.
higher pressures can develop when ventilator tidal volume is applied to a non-compliant lung because of interstitial and alveolar fluid
higher pressure could also because by a patient initiating breaths against the pressure of the ventilator
What is the benefit of adding PEEP on mechanical ventilation?
adding positive end-expiratory pressure to the ventilator circuit will increase FRC and hold more alveolar units open for participation in gas exchange (there are physiological costs including increase in mean airway pressure)
Does shunt contribute the increased PaCO2?
mostly that is caused by increased dead space, a large proportion of blood is required to be in shunt for that to e a factor in increasing PaCO2
What are the physiological costs of PEEP?
increased mean airway pressure (increase in intrathoric pressure?) due to PEEP can cause a decrease in venous return and negatively impact cardiac output and in few cases increases the risk of barotrauma
When in the time course of ARDS does fibrotic response become a problem?
as early as one week in the course of ARDS there is a fibrotic response which would be reflected in a restrictive pattern on pulmonary function test
DLCO is decreased due to loss of lung volume
