Ventilator-associated pneumonia (VAP) is among the most frequently occurring infections among critically ill patients, and its development is associated with poor patient prognosis. As such, VAP has been an important topic of clinical research in intensive care medicine, pulmonology, infectious diseases, and clinical microbiology. Yet, after more than 30 years of clinical studies on diagnosis, treatment, and prevention, a myriad of uncertainties remain.
Among the many challenges that confront our efforts to effectively treat VAP is that there is currently no reliable gold standard for diagnosis. Diagnosis is essentially based on a combination of clinical symptoms, microbiological test results, and radiological interpretations. These criteria, even in combination, are highly subjective and have suboptimal specificity. Subjective diagnosis of VAP hampers unbiased evaluation of the efficacy of preventive measures in unblinded studies and increases the risk of assessment bias when VAP rates are used as a quality metric. Poor specificity of the diagnosis leads to unnecessary antibiotic use and its associated harms. Of note, the diagnostic approach with better specificity, ie, bronchoscopic procedures combined with quantitative microbiological cultures, is hardly used because it is invasive and expensive.