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Abstract

Introduction: ADM is an endothelial-derived protein with multiple actions in the cardiovascular system, including modulation of cardiac and vascular contractility in response to disease, injury and shock states. VAP is associated with significant morbidity, mortality and cost. Our ICU VAP diagnosis protocol involves performing a BAL in patients with an elevated CPIS, starting antibiotics and deescalating or discontinuing them three days later when culture results become available. While this strategy can result in fewer missed VAP episodes, its use can result in patients being treated with antibiotics unnecessarily. This is the first characterization of the ADM response in patients with VAP. Hypothesis: ADM levels in BAL fluid correlate with a positive qualitative and quantitative culture and consequently the presence of VAP. Methods: An enzyme linked immunoabsorbent assay (ELISA) was used to measure serum ADM (ng/ml) in samples drawn from 57 intubated trauma patients in our surgical ICU (82% blunt, 18% penetrating) with elevated CPIS scores (average 6.75) in a 9 month period. The data was analyzed using t-test, and statistical differences were defined as p less than 0.05. Results: There were no significant demographic or clinical differences between patients with and without pneumonia, including their CPIS score. ADM levels were significantly higher in patients who ultimately had a positive culture. At a level of 584 ng/ml or higher, ADM had a sensitivity of 97% (83-99 CI) and a specificity of 82% (60-93). Area under the curve was 0.95. Conclusions: ADM levels in BAL fluid in patients with an elevated CPIS score correlate with the actual presence of VAP. This biomarker could potentially decrease the unnecessary use of antibiotics in patients who have an elevated CPIS but who do not have pneumonia. There is also potential for its use with, or in lieu of, screening BALs to predict the presence of community acquired pneumonia or patients at risk of developing pneumonia shortly after admission due to their injuries and not as a result of the care given to them. Further studies are needed to better understand the role of ADM in response to infection.