During acute respiratory distress syndrome (ARDS), computed tomography (CT) can reveal two distinct lung imaging patterns, focal or non-focal, with different responses to PEEP, recruitment maneuvers and prone position. Nevertheless, their association with plasma biomarkers and their distinct functional/pathobiological mechanisms are unknown. The objective of this study was to characterize focal and non-focal patterns of lung CT-based imaging with plasma markers of lung injury.
A prospective multicenter cohort study involving 119 consecutive ARDS patients. Plasma biomarkers [soluble form of the receptor for advanced glycation end product (sRAGE), plasminogen activator inhibitor-1 (PAI-1), soluble intercellular adhesion molecule-1 and surfactant protein-D] were measured within 24 hours of ARDS onset. Lung CT-scan was performed within the first 48 hours to assess lung morphology.
Thirty-two (27%) and 87 (73%) patients had focal and non-focal ARDS, respectively. Plasma levels of sRAGE were significantly higher in non-focal ARDS, compared to focal ARDS. A cut-off of 1188 pg/ml differentiated focal from non-focal ARDS with a sensitivity of 94% and a specificity of 84%. Non-focal patterns were associated with higher 28-day and 90-day mortality than focal patterns (31% vs 12%, p=0.038 and 46% vs 21%, p=0.026, respectively). Plasma levels of PAI-1 were significantly higher in non-focal ARDS. There was no difference in other biomarkers.
Plasma sRAGE is associated with a non-focal ARDS. Such novel findings may suggest a role for RAGE pathway in an underlying endotype of impaired alveolar fluid clearance and stimulate future research on the association between ARDS phenotypes and therapeutic responses.