Ventilator associated pneumonia: perspectives on the burden of illness

Objective: The objective of this narrative review is to summarize selected current concepts and clinical evidence regarding the burden of illness of VAP, including its epidemiology, diagnosis, attributable mortality and risk factors. Data Sources & Selections: Studies were identified through MEDLINE, EMBASE, bibliographies of primary and review articles and personal files. Results: While cross sectional studies inform us about VAP prevalence, longitudinal studies inform us of the cumulative risk and conditional risk of developing VAP. Reported VAP rates are modulated by factors related to case mix, causative micro-organisms, interventions that influence risk over time, and VAP definitions employed. Population-specific and organism-specific VAP rates are needed to avoid misleading benchmarking between different ICUs, and to minimize inappropriate between-study comparisons. Observational studies have shown that invasive sampling techniques versus non-invasive approaches to diagnose VAP facilitates more targeted antibiotic treatment; however, the influence of the diagnostic method on endpoints such as mortality is less clear. VAP is associated with approximately a 4 day increase in length of ICU stay and an attributable mortality of approximately 20-30 %. Fixed VAP risk factors include underlying cardiorespiratory disease, neurologic injury and trauma. Modifiable VAP risk factors include supine body position, witnessed aspiration, paralytic agents and antibiotic exposure. If modifiable risk factors tested in randomized trials lower VAP rates, such as semirecumbency versus supine positioning, these represent effective VAP prevention strategies. Conclusions: Ventilator-associated pneumonia is a major morbid outcome among critically ill patients. Studies evaluating more effective prevention and treatment strategies are needed.