The pathogenesis of VAP involves: 1. colonization of the aerodigestive tract. 2. aspiration of contaminated secretions into the lower airways. 3. increased use of silver-coated endotracheal tubes. 4. colonization of lower airways and lung parenchyma

a. 2 and 3 only
b. 2, 3, and 4 only
c. 1, 2, and 3 only
d. 1, 2, and 4 only

ANS: D
The pathogenesis of VAP most often involves colonization of the aerodigestive tract with path-ogenic bacteria, aspiration of contaminated secretions into the lower airways, followed by colo-nization of the normally sterile lower airways and lung parenchyma with these infectious micro-organisms. Recent studies have demonstrated that antimicrobial-coated ET tubes can reduce the incidence of VAP by delaying bacterial colonization and biofilm formation on the tube's inner lining. Laboratory studies have suggested that silver is an ideal coating because it is nontoxic, antimicrobial, and has anti-adhesive properties.