Tracheobronchial markers of lung injury in smoke inhalation victims

Although smoke inhalation injury victims frequently develop severe hypoxemia and are at increased risk of acute respiratory distress syndrome (ARDS), no early prognostic tests are currently available. The objectives were to determine early longitudinal changes in tracheobronchial fluid inflammatory markers and assess the value of initial concentrations as predictors of subsequent lung injury. Partial pressure of arterial oxygen (Pao2) and the fraction of inspired oxygen (Fio2) were recorded approximately every 6 hours from intubated smoke inhalation victims admitted to a regional burn center. Tracheobronchial suction fluid was collected every 2 hours and assayed for interleukins (IL-1β, -8, and -10), tumor necrosis factor-α, transforming growth factor-β1, soluble Fas ligand (sFasL), and complement factor 5a. Temporal trends in marker concentrations during 36 hours and the relations between initial concentrations and lowest Pao2/Fio2 or ARDS within 72 hours were assessed using random coefficients modeling and cross-sectional analysis. In 21 subjects with tracheobronchial samples collected within 6.5 hours of intubation, 14 (66.7%) developed acute hypoxemia (Pao2/Fio2 ≤200) within 72 hours of exposure and nine (42.9%) developed ARDS, as defined by the American-European consensus conference on ARDS. IL-8 increased sharply in the first 6.5 hours postexposure (P < .001), and IL-1β in the first 6.1 hours (P < .001). No significant temporal trends in IL-10, tumor necrosis factor-α, transforming growth factor-β1, sFasL, or complement factor 5a were found. Only initial IL-8 was associated with increased Pao2/Fio2 (P = .013) and with a minimum Pao2/Fio2 >200 (P = .042) during 72 hours. In smoke inhalation victims, tracheobronchial IL-1β and IL-8 increase rapidly and high initial IL-8 may predict improved oxygenation.