The decreasing incidence of late posttraumatic acute respiratory distress syndrome: the potential role of lung protective ventilation and conservative transfusion practice.

BACKGROUND: A reduction in the incidence of posttraumatic Acute Respiratory Distress Syndrome (ARDS) has been demonstrated. It is hypothesized that ventilation strategies and restrictive transfusion policies are contributory. The purpose of this study is to examine the changes in ventilation and transfusion parameters over time and their associations with late posttraumatic ARDS.
METHODS: The surgical intensive care unit and blood bank databases from a Level I center during a 6-year period were analyzed. All mechanically ventilated trauma patients were screened for ARDS with onset after 48 hours of admission (late ARDS). Demographic, injury, resuscitation, ventilation parameters, and transfusion data were extracted. Variables were analyzed for significant changes during the duration of the study, and independent associations with ARDS were determined.
RESULTS: There were 2,346 eligible patients and 192 (8.2%) of them met criteria for late ARDS. There was a significant decrease in the incidence of late ARDS by year (14.9% in 2000 to 3.8% in 2005). When comparing the first and second half of the study, there was a significant decrease in the percentage of patients transfused with packed red blood cells (49.0% versus 40.7%), patients with a peak inspiratory pressure > or = 30 mm Hg (64.9% versus 50.1%), and patients ventilated with a tidal volume/kg > or = 10 mL/kg (39.6% versus 21.8%). Early transfusions, peak inspiratory pressure > or = 30 mm Hg, and fluid balance > or = 2 L in the first 48 hours of admission were independently associated with ARDS.
CONCLUSIONS: The increasing use of restrictive transfusion policies and ventilation strategies that potentially limit elevations in early peak inspiratory pressures are associated with a decreased incidence of late posttraumatic ARDS.