Invasive versus noninvasive techniques for diagnosing ventilator-associated pneumonia

Abstract

For the last two decades, a more discriminative diagnostic approach for ventilator-associated pneumonia (VAP) has been the aim of extensive studies that have frequently yielded very different results. Enthusiasm has been shown for the diagnostic capacities of the protected-specimen brush and bronchoalveolar lavage performed under bronchoscopic guidance. More recently, some authors have demonstrated a comparable reliability for noninvasive diagnostic procedures. All of this has been rife with discrepancies and contradictory results, which have added to the confusion in this field. One of the reasons for this confusion is the lack of a representative gold standard. This has brought about studies that use histologic and postmortem microbiologic findings as a reference standard to compare results. This pattern, however, introduces obvious biases that have not dispelled all doubts. The impact of different diagnostic strategies on the outcome of severe pneumonia has been surprisingly overlooked until recently. Here again there are controversies that are probably the reflection of different epidemiologic situations and populations studied. The diagnostic strategy may not be the major determinant of outcome for patients with suspected VAP but, rather, whether adequate therapy is given as soon as VAP is clinically diagnosed. To increase the rate of appropriate initial antibiotic therapy, we suggest customizing guidelines according to local epidemiology and resistance patterns.