The diagnosis of VAP is challenging. Frequently, a presumptive
diagnosis of pneumonia is made when fever,
leukocytosis, purulent secretions, and a new infiltrate on
chest radiography develop and when bacteria are isolated
by nonquantitative analysis of endotracheal aspirates.
These nonspecific diagnostic criteria may lead to unnecessary
antibiotic use, increased hospital cost, emergence
of resistant microorganisms, and a potential delay in
diagnosis of the true cause of the fever. These problems
led several investigators to propose an invasive management
strategy for the diagnosis of VAP.