ABSTRACT
Hospital-acquired pneumonia (HAP) is the second most common nosocomial infection in
the critically ill patient and is associated with the greatest mortality and increased
morbidity and cost of care. The major risk factor for the development of HAP in intensive
care is the occurrence of intubation and mechanical ventilation, giving rise to the
term ventilator-associated pneumonia (VAP). Incidence of VAP varies in different populations of critically ill patients
and generally ranges from 9 to 20%, with an overall rate of 10 to 15 cases per 1,000
ventilator days. The cumulative risk of developing VAP is ~1% per day of mechanical
ventilation (MV). The crude mortality rate of VAP is 60% and the estimates of attributable
risk range from 27 to 43%. Mortality from VAP is influenced by host factors, the virulence
of the pathogens, and the adequacy of initial antimicrobial therapy. The etiologic
agents for VAP differ according to the population studied, duration of hospital stay,
time after intubation, and prior antimicrobial therapy. Risk factors include nonmodifiable
factors like age, chronic obstructive pulmonary disease, severe head trauma, and multiple
trauma, and modifiable factors like large volume gastric aspiration, duration of MV,
elevated gastric pH, histamine type 2 blocker therapy, ventilator circuit change frequency,
self-extubation, and reintubation. The impact that diagnosis using invasive diagnostic
techniques may have on the epidemiological characteristics of VAP are unknown, but
may potentially reduce problems resulting from misclassification of this entity.
KEYWORDS
Ventilator-associated pneumonia - antimicrobial therapy - intensive care unit - mechanical
ventilation
