Serial changes in soluble triggering receptor expressed on myeloid cells in the lung during development of ventilator-associated pneumonia

Objective: To determine the diagnostic role of soluble triggering receptor expressed on myeloid cells (sTREM)-1 in non-directed bronchial lavage fluid in ventilator-associated pneumonia (VAP). Design: Non-directed bronchial lavage fluid and plasma were collected on alternate days in critically ill mechanically ventilated patients from the start of ventilatory support until complete weaning from the ventilator. Soluble TREM-1 levels were measured by an enzyme-linked immunosorbent assay. Setting: A general adult medical and surgical university hospital intensive care unit. Patients: Nine patients who developed VAP and 19 patients who did not develop VAP (controls). Results: Plasma levels of sTREM-1 did not change significantly in either patient group. While in controls concentrations of sTREM-1 in non-directed bronchial lavage fluid did not change significantly over time, in patients who developed VAP levels of sTREM-1 in non-directed bronchial lavage fluid increased towards the diagnosis of VAP. A cut-off value for non-directed bronchial lavage fluid sTREM-1 levels of 200 pg/ml on the day of VAP had a diagnostic sensitivity of 75% and a specificity of 84%. Sensitivity increased when taking into account all sTREM-1 levels higher than 200 pg/ml from the 6-day period before the day of diagnosis that were preceded by an increase of at least 100 pg/ml (sensitivity 88%, specificity 84%). Conclusions: Soluble TREM-1 is a potential biomarker of VAP.