Distribution and function of alveolar cells in multiply injured patients with trauma-induced ARDS

To determine whether alveolar cells are involved in the pathogenesis of adult respiratory distress syndrome (ARDS), we assessed the distribution and function of alveolar cells from 30 polytraumatized patients with trauma-induced respiratory failure, 5 of whom also had lung contusion. Cells were obtained by bronchoalveolar lavage performed daily beginning on the day of trauma and continuing for 14 days. Neutrophils constituted about 60% of lavage cells in ARDS patients with lung contusion 0-2 days after polytrauma and about 50% in ARDS patients without lung contusion. In ARDS patients with lung contusion the neutrophil fraction decreased to 52% 3-6 days after trauma and to 40% 7-14 days after trauma. In patients without lung contusion the neutrophil fraction increased to 77% and then decreased to 60% at these times. Total cell counts in ARDS patients with lung contusion were more than twice as high as in patients without lung contusion 0-2 days after trauma. The difference in total cell counts decreased during days 3-6 and disappeared by day 7. In all patients morphologically altered alveolar cells were observed 4 days and more after trauma. In non-survivors significantly more altered cells were found. The chemiluminescence-response pattern of the alveolar cells was enhanced throughout the study and correlated with the neutrophil fraction (r = 0.6). The neutrophil fraction also correlated with the pulmonary vascular resistance during the first two days after trauma (r = 0.53). We conclude that alveolar cells are involved in the pathogenesis of trauma-induced ARDS and that the alveolar cell distribution is different in patients with and without lung contusion during the development of posttraumatic respiratory failure.