Soluble triggering receptor expressed on myeloid cells (s-TREM-1) from endotracheal aspirates in critically ill patients: A potential marker of the dynamic inflammatory burden of the lower respiratory tract

Abstract

Objectives. The current study was designed to evaluate the role of Soluble Triggering Receptor Expressed on Myeloid Cells (s-TREM-1) measured in samples of endotracheal aspirates from critically-ill, intubated patients as a marker of inflammation or pneumonia.

Methods. The Clinical Pulmonary Infection Score (CPIS), a commonly utilized clinical predictor of ventilator-associated pneumonia (VAP), was calculated for each patient at the same time that endotracheal aspirates were obtained using sterile techniques, in order to correlate this with s-TREM-1 concentrations determined in the laboratory using a validated ELISA procedure.
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Results. Thirty patients (2- 39 days in ICU) were included in the study. Soluble-TREM-1 was detectable in endotracheal aspirates from all patients and a wide range of concentrations from 13 to > 4000 pg/ml was observed. The mean s-TREM-1concentrations for patients with a CPIS < 6 (n=15) compared to those with a CPIS ≥ 6 were 592 ± 288 and 382 ± 119 pg/ml respectively (p> 0.05).

Conclusions. Soluble-TREM-1 is readily detectable and quantifiable in endotracheal aspirates from critically ill patients, but does not correlate with the CPIS. The wide range of measured s-TREM-1 concentrations suggests that this pro-inflammatory marker may reflect the dynamic inflammatory burden of the lower respiratory tract increasing progressively as colonization by microbial pathogens leads to ventilator-associated tracheobronchitis (VAT) and ultimately VAP. Therefore, serial determinations of s-TREM-1 in this setting may be of greater value than the CPIS in differentiating VAT from VAP and thus provide an alternative threshold for the initiation of empirical anti-microbial therapy.