Relative changes in plasma levels of biomarkers of inflammation (TNF-α, IL-6, IL-8, sRAGE) or lung injury (SP-D, CC-16, KL6) in patients who developed (closed symbols) or did not develop (open symbols) one or more postoperative pulmonary complications. Box plots show medians (horizontal line within the box), interquartile ranges (lower and upper edges of the box) and the 10th to 90th percentile range (ends of whiskers). P values indicate the statistical significance. CC-16, Clara cell protein; IL, interleukin; KL6, Krebs von den Lungen-6; SP-D, surfactant protein D; sRAGE, soluble receptor for advanced glycation end-products; TNF, tumour necrosis factor.