Plasma levels of soluble receptor for advanced glycation end products in patients with acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure associated with severe inflammation and diffuse alveolar damage. Recent studies have demonstrated that the soluble receptor for advanced glycation end products (sRAGE) plays an important role in the pathogenesis of ARDS. The aim of this study was to ascertain whether plasma levels of sRAGE were elevated in ARDS patients compared with appropriate controls. Furthermore, we explored whether plasma levels of sRAGE were related to disease severity, ventilatory parameters and clinical outcome. We prospectively enrolled twenty-two ARDS patients, fourteen ventilated controls and twelve healthy subjects. The Sequential Organ Failure Assessment (SOFA) score was applied to assess illness severity. In addition, ventilator parameters (arterial oxygen tension (PaO2): inspiratory oxygen fraction (FiO(2)) ratio, arterial carbon dioxide tension (PaCO2), tidal volume and positive end-expiratory pressure (PEEP)) of ARDS patients and ventilated controls were also recorded. Plasma samples were collected within 24 hours and levels of sRAGE were determined using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) kit. Possible correlation between plasma sRAGE levels and clinical parameters were explored using a simple linear model. Plasma sRAGE levels were significantly elevated in the plasma samples taken from patients with ARDS (1797 +/- 383 pg/ml) when compared with both ventilated (650 +/- 192 pg/ml, P < 0.01) and healthy (415 +/- 178 pg/ml, P < 0.01) controls. Significant correlations were found between plasma sRAGE levels and PaO2: FiO(2) ratio (P < 0.05, r=0.36). There was no significant difference in plasma sRAGE levels between survivors and non-survivors (P=0.34). Our results demonstrate that elevated levels of plasma sRAGE may provide a useful marker for ventilated ARDS patients. Furthermore, the relationship between plasma sRAGE levels and PaO2: FiO(2) ratio in the ARDS population provides the hypothesis that ventilatory strategy may influence alveolar epithelial damage in ARDS.