Evolution of Tracheobronchial Colonization Following Tracheal Intubation in Patients With Neurologic Injury Who Are Ventilated

Background

The characteristics and course of endotracheal secretions have scarcely been studied in patients under mechanical ventilation (MV) at risk of developing ventilator-associated pneumonia (VAP).

Research Question

Can endotracheal secretions be exhaustively described and what is their predictive value for the diagnosis of VAP during MV?

Study Design and Methods

This single-center prospective study included neuro-injured patients with neurologic injury requiring MV for at least 7 days. Patients with pulmonary and infectious diseases were ineligible. All endotracheal aspirates (ETAs) collected between tracheal intubation and day 7 were analyzed. Macroscopic characteristics and microbiology were assessed. Clinical Pulmonary Infection Score was calculated daily. An anonymized adjudication committee validated all VAP events.

Results

Forty-eight patients and 1,544 ETAs were analyzed. Overall, 81% of the ETAs were purulent, and 50% were thick. Culture results showed high interindividual and intraindividual variability. Ten patients (21%) developed early-onset VAP. Eight patients (80%) with VAP and 14 (37%) without VAP had a Clinical Pulmonary Infection Score > 6. The day prior to VAP diagnosis, a 20 mL increase in ETA volume detected VAP with a sensitivity of 67% and a specificity of 93%.

Interpretation

This study provides new information regarding the course of respiratory colonization in patients who are mechanically ventilated and suggests that ETA color/aspects and pathogen kinetics cannot predict VAP. Traditional VAP criteria (Clinical Pulmonary Infection Score and bacterial load) also had a low diagnostic specificity. Conversely, an increase in secretion volume should alert for VAP development.