Alternative case definitions of ventilator-associated pneumonia identify different patients in a surgical intensive care unit

Diagnostic criteria that define ventilator-associated pneumonia (VAP) remai n controversial. The purpose of this study was to evaluate common definitio ns of VAP and determine their relationship to each other and clinical treat ment. This study prospectively evaluated several diagnostic criteria that d efine VAP in a cohort of 255 consecutive SICU patients ventilated for < 48 h. Definitions evaluated include the CDC definitions, the Johanson definiti ons which do not rely on culture data, the Physician's Probable diagnosis w hich relies on positive quantitative cultures, and the antibiotic treatment group. Forty-four patients (17%) received antibiotic treatment for VAP. De pending on the definition evaluated, criteria were met for a diagnosis of V AP from as low as 4% of patients by the Johanson definition to as high as 4 8% of patients by the CDC definition. There was poor agreement among the de finitions in their ability to select the same patient as having VAP, Beside s duration of mechanical ventilation and tube feeding, which were risk fact ors that predicted meeting the criteria for all groups, risk factors predic ting VAP varied among the definitions. This study demonstrates that in a su rgical ICU, the candidate definitions of pneumonia evaluated show little ag reement. The particular case definition chosen to diagnose VAP will determi ne the incidence rate of pneumonia, the time to onset of pneumonia, and the risk factors of the type of patient treated.