Introduction
The first report of acute respiratory distress syndrome (ARDS) in 1967 by Ashbaugh et al 1 described a clinical syndrome of severe dyspnea, tachypnea, cyanosis refractory to oxygen therapy, loss of lung compliance, and diffuse alveolar infiltrates on chest radiograph. Once the pathophysiology was elucidated, it became clear that this syndrome was characterized by an increased permeability of the alveolar–capillary barrier, resulting in lung edema with protein-rich fluid causing an impairment in arterial oxygenation. Lung edema and endothelial and epithelial injuries are accompanied by an influx of neutrophils into the interstitium and bronchoalveolar space. Activation and recruitment of neutrophils play an important role in the progression of ARDS. Neutrophils are the first cells to be recruited to the site of inflammation and have a potent antimicrobial defense that includes oxidants, proteinases, and cationic peptides. Under pathologic circumstances, however, unregulated release of these microbicidal compounds into the extracellular space paradoxically can cause damage to the host tissues. Clinical data and animal models have proved the importance of neutrophils in ARDS.2
Historically, ARDS has been a significant cause of trauma-related morbidity and mortality, with reported mortality rates up to 40%.3 4 Many treatment strategies have been created; however, most of them had limited success.5 Nowadays, treatment is still limited and mainly consists of supportive mechanical ventilation with low tidal volume and inspiratory pressure ventilation. Therefore, prevention of ARDS is important and identification of risk factors has been subject to many research studies.6–10 To early identify patients at risk for ARDS development, several prediction models have been created. Age, Injury Severity Score (ISS), severity of chest injury, crystalloids transfusion, and blood product transfusion have been identified as predictors of ARDS in trauma.7–11
With improvement of trauma and critical care, mortality caused by ARDS has decreased in the last years.6 7 9–12 However, it still uses significant intensive care unit (ICU) resources and remains an important cause of trauma-related deaths.
In contrast to several studies6 7 9–12 reporting up to 20% ARDS-related deaths, we did not observe high ARDS incidence and related death rates anymore in our polytrauma population in the last few years. Therefore, we conducted a prospective population-based cohort study in polytrauma patients to investigate the current incidence of ARDS and its contribution to mortality. We hypothesized that both the incidence of ARDS and mortality caused by ARDS were decreased compared with internationally reported data.