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
?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).
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