Systemic Inflammatory Response as a Risk and Prognosis Factor in Ventilator-Associated Pneumonia

Abstract

Any important aggression toward our bodies leads to a complex systemic inflammatory response that can be expressed by biomarkers. Thus biomarkers can help us to diagnose and manage the initial aggression. Application of biomarkers to ventilator-associated pneumonia (VAP) has two additional difficulties: the lack of universal consensus regarding the diagnostic criteria and the difficulty of discriminating the inflammatory response secondary to VAP in a context (that of ventilated critical-care patients) in which there is already a nonspecific inflammatory response. However, biomarkers have been studied in VAP and promising results have been achieved concerning diagnosis and follow-up. The most studied biomarkers have been C-reactive protein, procalcitonin, sTREM-1 and cytokines. Nevertheless, heterogeneicity of results makes difficult to apply conclusions to the general ICU population. Authors differ in VAP diagnosis criteria and in the selection of the control group (in some studies other infections different from VAP cause changes in serum biomarkers). The true diagnostic value of these substances lies in reinforcing the habitual clinical algorithm; when interpreting the results, we should take into consideration all the factors that may modify the inflammatory response. Keywords: Biomarkers, ventilator-associated pneumonia, C-reactive protein, procalcitonin, sTREM-1, cytokines