What is the effect of oral chlorhexidine use and removal of oral secretions prior to position changing on the development of ventilator-acquired pneumonia?

Numerous risks factors contribute to the development of ventilator-acquired pneumonia as mechanical ventilation presents a unique set of challenges for the patient requiring intubation and ventilator support. Rigorous clinical studies show oral secretions pose an increased risk for developing VAP (Augustyn, 2007). Treatments, strategies and evidence-based interventions have been developed to decrease the risks and reduce the prevalence of VAP. There is evidence indicating the use of oral chlorhexidine and the removal of oral secretions before position changes may diminish the risks of developing ventilator-acquired pneumonia. By reducing the levels of bacteria in the oropharynx there would theoretically be a decrease in the prevalence of nosocomial pneumonia (Houston et al., 2002). Research demonstrates the use of 0.12% chlorhexidine gluconate oral rinse (CHX) pre and postoperatively reduces the incidence of VAP in patients who are intubated greater than 24 hours.
Foreground Question
In adults supported with mechanical ventilation, what is the effect of oral chlorhexidine use and removal of oral secretions prior to position changing on the development of ventilator-acquired pneumonia?