Ventilator-associated tracheobronchitis: where are we now?

Ventilator-associated tracheobronchitis (VAT) is a common intensive care unit (ICU)-acquired infection. Its incidence ranges from 1.4 to 19% of critically ill patients receiving invasive mechanical ventilation.(1-4) This infection is considered as an intermediate process between colonization and ventilator-associated pneumonia (VAP).(5) Histological studies revealed a continuum between these two infections. Several definitions are available for VAT. However, all of these definitions have some limitations. The most accepted and frequently used definition include the following criteria: fever >38o C with no other cause, purulent tracheal secretions, positive tracheal aspirate (≥105cfu/mL), and absence of new infiltrate on chest X-ray.(2) VAT is frequently caused by Gram-negative bacilli. Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii are the most common pathogens isolated from respiratory secretions of VAT patients.(6) Previous studies have reported a prolonged duration of mechanical ventilation and a prolonged ICU stay in VAT patients.(4,7) This negative impact on patient outcome is related to increased inflammation of the lower respiratory tract and sputum production. Extubation failure has been noted, and difficult weaning could result from increased sputum production. In addition, higher rates of VAP were reported in patients with VAT compared with those without VAT. In a recent multicenter observational study conducted in 122 VAT patients,(8) the incidence of VAP was two-fold higher in patients with VAT compared with those without VAT (13.9% versus 7%). Although the mortality attributed to VAP remains a matter for debate, VAP is associated with a longer duration of mechanical ventilation, longer length of ICU stay, and increased hospital cost.(9) A recent international survey was conducted to determine the current practices in the clinical and microbiological diagnosis of VAT and to evaluate perceptions of the impact of VAT on patient outcomes.(10) A total of 288 ICUs from 16 different countries answered the survey, including 147 (51%) from Latin America and 141 (49%) from Spain, Portugal, and France. The majority of respondents (n=228; 79.2%) reported making the diagnosis of VAT based on clinical and microbiological criteria, and 40 (13.9%) reported making the diagnosis based on clinical criteria alone. Approximately half (50.3%) of the respondents agreed that patients should receive antibiotics for the treatment of VAT. Out of all respondents, 269 (93.4%) assumed that a VAT episode increases the ICU length of stay. Half of the physicians felt that VAT increases the risk of mortality. Two recent randomized studies evaluated the impact of antimicrobial treatment on the outcome of VAT patients.(11,12) The first was a randomized Saad Nseir1,2, Ignacio Martin-Loeches3