What evidence indicates biotrauma may be a mechanism of ...

[Engineer]

What evidence indicates biotrauma may be a mechanism of ventilator-induced lung injury (VILI)?
 
  A. the presence of increased tumor necrosis factor- in the serum of animals receiving low lung volumes and PEEP
  B. the presence of increase neutrophils and alveolar macrophages in the mucus of animals ventilated with low lung volumes and high pressures
  C. the increased incidence of alveolar-capillary permeability in animals ventilated with high lung volumes and no PEEP
  D. the presence of increased inflammatory mediators in broncho-alveolar lavage in animals receiving high lung volumes and no PEEP

Question 2

Which of the following ventilator conditions appear to be the most important mechanism for ventilator-induced lung injury?
 
  A. excessive lung volumes and alveolar overdistention
  B. low lung volumes and no PEEP
  C. increased inspiratory time and increased respiratory rate
  D. repeated cyclic opening and closing of alveoli at low lung volumes

[harveenkau8139]

Answer to Question 1

ANS: D
A. Incorrect response: Chiumello et al found higher levels of tumor necrosis factor- (TNF-) and macrophage inflammatory protein-2 (MIP-2) in the serum of animals that developed lung injury while receiving high tidal volumes and no PEEP.
B. Incorrect response: Haitsma et al found results similar to Chiumello and colleagues regarding TNF- in a model of lipopolysaccharide-induced lung injury.
C. Incorrect response: The demonstration of an increased incidence of alveolar-capillary permeability in animals ventilated with high lung volumes and no PEEP is evidence of volutrauma, not biotrauma.
D. Correct response: A number of studies have provided evidence that an increase in bronchoalveolar lavage and serum concentrations of inflammatory cytokines and chemokines indicate a strong relationship between biotrauma and VILI in animals ventilated with high lung volumes.

Answer to Question 2

ANS: A
A. Correct response: Excessive tidal volumes with alveolar overdistention may be the most important mechanism in VILI, and the term volutrauma is appropriate to describe the sequelae.
B. Incorrect response: Chu et al, in an ex vivo rat lung model, found that bronchoalveolar lavage (BAL) inflammatory mediators concentrations were greater in lungs ventilated at low lung volumes and no PEEP than at low tidal volumes and PEEP of 5 cm H2O, or at low volumes while remaining atelectatic.
C. Incorrect response: See explanation C.
D. Incorrect response: Chu et al found that repeated cyclic opening and closing is injurious at low lung volumes (atelectrauma).

[Engineer]

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