The clinical diagnosis of ventilator-associated pneumonia

Abstract

There has long been a controversy about whether to use a clinical or microbiologic approach to diagnose ventilator-associated pneumonia (VAP) and about which approach to use in managing patients. Although the clinical approach has often been criticized, a number of recent studies have shown that it is possible to use such an approach to effectively manage patients. This approach involves using all available clinical data to define the presence of pneumonia and then to initiate empiric therapy in a timely fashion, based on therapy guidelines, modified by local microbiologic data. Often the clinical diagnosis is made using the clinical pulmonary infection score, and this tool can be very accurate, especially if it incorporates a Gram stain of a lower-respiratory-tract sample. Once the clinical diagnosis of VAP is made, all patients should have a tracheal aspirate collected for culture, followed by prompt initiation of therapy. Using a clinical approach to management, the key decision point is not whether to start antibiotics, but whether to continue them at day 2-3. This requires serial clinical evaluation to define whether a response to empiric therapy has occurred. Based on this assessment, in conjunction with the results of tracheal aspirate cultures, therapy can be either modified or continued. A number of studies have shown that the clinical approach leads to a large number of patients receiving adequate empiric therapy, while still permitting de-escalation of antibiotic regimens, along with short durations of therapy. Thus a clinical approach to management can be successful in allowing for effective management of VAP, without promoting the unnecessary use of broad-spectrum antimicrobial therapy.