VAP is associated with increased health care costs, morbidity, and mortality. Chlorhexidine oral swabbing was effective in reducing early VAP in patients in medical, surgical/trauma, and neuroscience ICUs who did not have pneumonia at baseline. Toothbrushing did not reduce the incidence of VAP, and combining toothbrushing and chlorhexidine did not provide additional benefit over use of chlorhexidine alone.
This project was a randomized, controlled clinical trial to determine if 2 oral care interventions, chlorhexidine and toothbrushing, would reduce the risk for VAP during the first week of intubation in critically ill adults receiving mechanical ventilation. The sample was diverse in race and included both men and women. Severity of illness was appropriate for a large urban medical center, and the VAP rate observed was similar to published rates.31
In our previous studies on the effect of oral health status on development of VAP, we found that increased dental plaque was predictive of pneumonia in patients with lower baseline CPIS values.32
At that time, we speculated that patients who did not yet have indications of pulmonary infection might derive the most benefit from interventions to reduce dental plaque. The finding in the current study that chlorhexidine was beneficial on day 3 in the subset of patients who had baseline CPIS values <6 but not in the total sample supports the idea of a differential benefit of a reduction in the number of oral organisms based on level of pulmonary infection, with more benefit in those without preexisting infection.
The toothbrushing protocol did not have a significant effect on VAP. Although both chlorhexidine and toothbrushing control organisms in dental plaque, chlorhexidine has bactericidal activity, whereas toothbrushing mechanically reduces the number of organisms without residual activity on the organisms remaining in the mouth. The intermittent reduction in the number of organisms by toothbrushing was insufficient to reduce the risk for pneumonia.
The most recent (2004) Centers for Disease Control and Prevention recommendations9
for prevention of nosocomial bacterial pneumonia in patients receiving mechanical ventilation specifically address the importance of oral microbial flora in the development of VAP. Recommendations for patients having elective cardiac surgery include the use of chlorhexidine during the perioperative period and are based on the results of studies19–21
in which patients began using chlorhexidine before hospital admission for elective cardiac surgery and chlorhexidine use was continued throughout the hospital stay. However, for other critically ill patients, the oral care recommendations are much more general, and evidence available when the guidelines were updated was insufficient for making a recommendation for use of chlorhexidine in the general ICU population.
Toothbrushes are generally regarded as the best tool for mechanical oral care in healthy populations. In this study we hypothesized that a defined toothbrushing intervention would reduce risk of VAP; it did not. Despite great enthusiasm among bedside nurses regarding the theorized effect of oral care on VAP reduction, few data support the effectiveness of mechanical oral care procedures. Most studies are anecdotal or a nonexperimental design was used, and many studies included oral care as one component of a VAP reduction program that included interventions with proven efficacy (including elevation of the head of the bed), with all interventions tested together as a bundle.
Chlorhexidine reduced rates of ventilator-associated pneumonia in patients without pneumonia at baseline.
For example, in a study often used as supporting evidence for the efficacy of oral care in reducing the rate of VAP, Zack et al33
conducted an observational study of VAP rates in a single hospital 12 months before and 12 months after providing an educational self-study program about VAP reduction to respiratory care practitioners and ICU nurses. A decrease in VAP (P
< .001) was noted in the year after the educational program. However, oral care (″provide oral hygiene at least once daily″) was only 1 of 14 recommendations, which also included extubating patients as soon as possible, elevating the head of the bed, reducing unnecessary use of antibiotics, and ventilatory circuit management). The direct contribution of toothbrushing to VAP reduction was not ascertainable. In a follow-up study34
conducted by the same group using the same design in 4 hospitals (a pediatric teaching hospital, an adult teaching hospital, and 2 community hospitals in an integrated health system), combined VAP rates decreased significantly (P
< .001) even though the recommendation for routine oral hygiene was omitted.
Toothbrushing alone did not reduce ventilator-associated pneumonia, and combining toothbrushing with chlorhexidine did not provide additional benefit over chlorhexidine alone.
Chlorhexidine is a broad-spectrum antibacterial agent that has been used extensively in healthy populations as an oral rinse to control dental plaque and to prevent and treat gingivitis.35,36
Microbial resistance to chlorhexidine has not been demonstrated, and the drug has minimal side effects. Three investigative teams19–21
have shown the effectiveness of oral chlorhexidine in reducing nosocomial respiratory tract infections in patients having elective cardiac surgery. Importantly, in each of these studies, the intervention was begun preoperatively (before intubation) and was continued throughout the ICU stay. However, cardiac surgery patients who have elective surgery most likely have different comorbid conditions and better physiological status at the time of intubation than do patients in the general adult ICU population. Studies in patients having elective cardiac surgery focused broadly on nosocomial infection (including surgical infection and tracheobronchitis) rather than on VAP.
Risk of ventilator-associated pneumonia begins with intubation; so too should prevention efforts.
Recently, chlorhexidine has been investigated in other ICU populations as well. Koeman et al37
randomized patients to a control group or to oral topical application of either 2% chlorhexidine or 2% chlorhexidine with colistin. Both chlorhexidine groups had reduced daily risk of VAP compared with control patients (chlorhexidine vs control, P
= .01; chlorhexidine plus colistin, P
= .03). Of note, the concentration of chlorhexidine used by Koeman et al was higher than the dental solution of 0.12% approved by the Food and Drug Administration that was used in our study and in other reported studies. In a randomized controlled trial of 0.2% chlorhexidine vs placebo in 228 ICU patients, Fourrier et al38
found no effect of chlorhexidine on VAP rate, with reported VAP rates of 11 % in each group. In our current study, topical application of chlorhexidine 0.12% solution to the oral cavity significantly reduced the incidence of pneumonia on day 3 among patients who did not have pneumonia at baseline (P
The smaller sample sizes on days 5 and 7 did not allow conclusions about the effect of the interventions on late-onset VAP. The target population of critically ill adults is difficult to study because of their heterogeneity of underlying medical conditions, rapid changes in health status, numerous intervening variables, and uncontrollable attrition due to death or extubation. Additionally, our study design specified recruiting patients within the first 24 hours of intubation and obtaining prospective informed consent from potential patients’ legally authorized representatives during a stressful period. These requirements further limited enrollment of patients.