ABSTRACT
The concept of ventilator-induced lung injury includes three different patho-
physiological entities: high permeability type pulmonary edema resulting from high tidal volume ventilation-‘‘volutrauma’’ (1), lung inflammation
resulting from repetitive opening and closure of distal bronchioles-
‘‘biotrauma’’ (2), and mechanical distortion/overinflation of anatomical
lung structures (3). The first two have been identified from experimental stud-
ies (4,5) and have found some indirect confirmation in humans (6,7) but
remain to date a subject of controversy (8). The latter is a hallmark of human
ventilator-induced lung injury. Lung distortion/overinflation was discovered
on human lung autopsies more than 25 years ago (9-12), was recently demonstrated to result from prolonged mechanical ventilation in experimental
animals (13), and is easy to evidence using whole lung computed tomography
(CT) (14,15). Surprisingly, pulmonary edema resulting from ‘‘volutrauma’’
and lung inflammation resulting from ‘‘biotrauma’’ have been the focus,
the attention of most recent reviews on ventilator-induced lung injury despite
their uncertain human clinical relevance, whereas the well-demonstrated
morphological overinflation resulting from mechanical ventilation-induced distortion of human lungs is only incidentally reported. The present article
is aimed at reviewing the imaging of lung overinflation resulting from
mechanical ventilation. In critically ill patients with acute lung injury, whole
lung CT occupies a central role in evidencing pulmonary lesions resulting
from positive pressure ventilation.
