From starting mechanical ventilation to ventilator-associated pneumonia, choosing the right moment to start antibiotic treatment

BACKGROUND: Ventilator-associated pneumonia (VAP) can have a clear onset or may be a result of the gradual appearance of symptoms and signs of VAP (gradual VAP). The aim of this paper is to describe the VAP development process with the intention of discriminating between those pneumonias with a clear beginning and those that are diagnosed after a period of maturation. In addition, we evaluate the effect of the starting time of antibiotic treatment in both situations. METHODS: Consecutive ventilated patients fulfilling VAP criteria were included. The patients were monitored for clinical, microbiological, and inflammatory signs. Patients with VAP were classified into two groups: (1) nongradual VAP (patients in whom all VAP criteria were detected for the first time on the day of diagnosis) and (2) gradual VAP (progressive appearance of signs and symptoms throughout the pre-VAP period [<96 h to >24 h before VAP diagnosis]). RESULTS: A total of 71 patients with VAP were identified, of whom 43 (61 %) had gradual VAP, most of whom (n = 38, 88 %) had late-onset VAP. Antibiotic treatment was given to 34 (79 %) patients with gradual VAP in the pre-VAP period, and empirical antibiotic treatment was appropriate in 22 patients (51 %). The patients with an appropriate empirical treatment had a higher percentage of early clinical response to treatment (68 % [n = 15] vs. 28 % [n = 7]; p = 0.009). An attempt was made to find a diagnostic test capable of identifying the infectious process underway, but clinical scales and biomarkers of inflammation helped us to achieve acceptable results. CONCLUSIONS: Gradual emergence of VAP, mainly of late onset, is a common condition. Clinicians should be aware of this gradual onset of the infection to establish an early antibiotic treatment, even before the classic diagnostic criteria for VAP are applied.