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Abstract |
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 Top Abstract HypothesisMaterials and MethodsResultsDiscussionReferences |
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• Objectives To test the effectiveness of 0.12% chlorhexidine gluconate oral rinse in decreasing microbial colonization of the respiratory tract and nosocomial pneumonia in patients undergoing open heart surgery.
• Methods A prospective, randomized, case-controlled clinical trial design was used. Peridex (0.12% chlorhexidine gluconate) was the experimental drug, and Listerine (phenolic mixture) was the control drug. A total of 561 patients undergoing aortocoronary bypass or valve surgery requiring cardiopulmonary bypass were randomized to an experimental (n = 270) or a control (n = 291) group. Nosocomial pneumonia was diagnosed by using the criteria established by the Centers for Disease Control and Prevention.
• Results The overall rate of nosocomial pneumonia was reduced by 52% (4/270 vs 9/291; P = .21) in the Peridex-treated patients. Among patients intubated for more than 24 hours who had cultures that showed microbial growth (all pneumonias occurred in this group), the pneumonia rate was reduced by 58% (4/19 vs 9/18; P = .06) in patients treated with Peridex. In patients at highest risk for pneumonia (intubated >24 hours, with cultures showing the most growth), the rate was 71% lower in the Peridex group than in the Listerine group (2/10 vs 7/10; P = .02).
• Conclusions Although rates of nosocomial pneumonia were lower in patients treated with Peridex than in patients treated with Listerine, the difference was significant only in those patients intubated more than 24 hours who had the highest degree of bacterial colonization.
The Centers for Disease Control and Prevention postulates 4 possible mechanisms that lead to nosocomial pneumonia: (1) aspiration of oropharyngeal organisms, (2) inhalation of aerosol that contains bacteria, (3) hematogenous spread from distant body sites, and (4) bacterial translocation from the gastrointestinal tract. Aspiration of organisms from the oropharynx is considered the most important of these mechanisms.3 Reducing levels of bacteria in the oropharynx would theoretically lead to a decrease in the prevalence of nosocomial pneumonia.
Peridex (0.12% chlorhexidine mouth rinse) is an antimicrobial agent effective against aerobic and anaerobic bacteria. It is a substantive rinse that is adsorbed onto soft tissues and released over time.4 Within 1 minute after administration, the total numbers of aerobes and anaerobes are reduced 87% and 84%, respectively, and bacterial counts actually decrease over time (88% and 92% reduction, respectively, 5 hours later).5
Several investigators have evaluated the effects of 0.12% chlorhexidine mouth rinse on plaque and gingival inflammation. Brownstein et al6 reported significantly reduced plaque accumulation, decreased gingival bleeding, and a lower mean log of colony-forming units of Actinomyces species with either twice-daily rinses or once-a-day irrigation. Beiswanger et al7 studied the effect of a 0.12% chlorhexidine rinse on gingival healing after scaling and root planing. After baseline measurements were recorded, test subjects used 15 mL (
oz) of chlorhexidine twice daily for 30 seconds 2 weeks before and 2 weeks after scaling and root planing of opposing quadrants on one side of the mouth. Then the remaining quadrants were treated, and an additional 2 weeks of chlorhexidine use were completed. Compared with the control groups, who used placebo, subjects who used the chlorhexidine rinse had significantly better gingival healing. The subjects in the test group had 29% less gingivitis, 48% fewer bleeding sites, and 54% less plaque.
Corbet et al8 investigated the effect of 0.12% chlorhexidine in a population with established gingivitis and abundant plaque and calculus in a double-blind clinical design, with 60 subjects divided into 2 groups. The experimental group was assigned to 2 daily mouth rinses for 6 days per week with 0.12% chlorhexidine, whereas the control group rinsed twice daily with a placebo solution. Before and after 3 months of supervised rinsing, plaque and gingivitis were assessed and scored. After 3 months, significant reductions in gingival bleeding and plaque occurred in the chlorhexidine group. Since that study, numerous studies have proved the effectiveness of chlorhexidine as an oral decontamination agent. Recently, DeRiso et al9 examined the effectiveness of 0.12% chlorhexidine on nosocomial infection in a homogeneous population of patients undergoing heart surgery. A prospective, randomized, double-blind, placebo-controlled design was used. A total of 353 patients undergoing open heart surgery were randomly assigned to the chlorhexidine or placebo groups. The overall nosocomial infection rate was decreased by 65% in the chlorhexidine-treated patients compared with the rate in patients given placebo (24/180 vs 8/173; P < .01). Overall, use of chlorhexidine oral rinse reduced the total nosocomial respiratory infection rate and the use of nonprophylactic systemic antibiotics in patients who had heart surgery.
St. Luke’s Episcopal Hospital in Houston, Tex, is a tertiary care center where many cardiovascular patients who require cardiopulmonary bypass are admitted (>1500 cases per year). Historically, more than 50% of cases of nosocomial pneumonia in the hospital occurred in cardiovascular patients. Listerine brand phenolic mouth rinse was used at St. Luke’s as the standard agent for routine oral care. Unlike Peridex, Listerine is a nonsubstantive agent—one that kills bacteria upon application but does not persist in tissues. Previous direct comparisons10 indicated that Peridex is more effective than Listerine both immediately and over time.
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Hypothesis |
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TopAbstractHypothesisMaterials and MethodsResultsDiscussionReferences |
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Materials and Methods |
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TopAbstractHypothesisMaterials and MethodsResultsDiscussionReferences |
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After informed consent was obtained, patients were consecutively randomized to the experimental or the control group according to the patients’ medical record numbers. A sample size of 600 was projected on the basis of the institution’s historical rate of nosocomial pneumonia. This sample size was sufficient to detect a 0.20 effect size with 99% power. The oral rinses were dispensed by pharmacists and were administered by staff nurses. Both experimental and control groups received the oral rinse preoperatively and twice daily for 10 days postoperatively or until extubation, tracheostomy, death, or diagnosis of pneumonia. Most of the patients received only 2 doses of the oral rinse agents as part of the study protocol, because extubation routinely occurred within 4 to 8 hours after surgery.
Patients received 15 mL of the experimental or the control drug preoperatively, and they were instructed to vigorously swish and gargle the solution for 30 seconds to ensure contact with the buccal, gingival, tongue, pharyngeal, and tooth surfaces. Subjects were told to avoid ingesting either oral rinse and not to eat or drink for 30 minutes after rinsing. Postoperatively, 15 mL of oral rinse was administered to intubated patients twice a day by thoroughly swabbing the surfaces in the patient’s oral cavity.
Sputum samples were collected at the time of extubation. If subjects were not extubated within 24 hours of surgery, sputum samples were obtained routinely every 48 hours until extubation. Sputum samples were sent to the institution’s clinical microbiology laboratory and processed according to standard procedures. Samples were inoculated onto solid agar media, incubated at 35°C, and examined at 24 hours and 48 hours for the growth of respiratory pathogens. A semiquantitative assessment of growth was determined as follows: light growth (1+), moderate growth (2+), and heavy growth (3–4+). Gram-positive and gram-negative respiratory pathogens were identified to the genus and species level by using standard microbiological methods. The subjects in both groups received preoperative and perioperative prophylactic antibiotics as part of a routine heart surgery protocol (cefuroxime 1.5 g preoperatively and 2 doses every 12 hours postoperatively for 24 hours for aortocoronary bypass patients or vancomycin 1.0 g preoperatively and 2 doses every 12 hours postoperatively for valve surgery patients).
Infections were diagnosed by using a tool based on the criteria for nosocomial pneumonia established by the Centers for Disease Control and Prevention.11 The scoring tool included nature of tracheobronchial secretions, evidence of fever, degree of leukocytosis, microbial culture results, and evidence of pulmonary infiltrate. Subjects had to have a new or progressing pulmonary infiltrate to have pneumonia diagnosed. Nosocomial pneumonia was diagnosed independently by the physician and infection control practitioner. Interrater reliability was established at 98%.
All statistical analyses were done with Statistical Analysis Software (SAS, Cary, NC). Analysis of variance and 
2 tests were used to compare patients’ characteristics between groups. The 2 test with Yates correction was used to address the research questions. Statistical significance was set at P < .05.
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Results |
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TopAbstractHypothesisMaterials and MethodsResultsDiscussionReferences |
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). Durations of intubation were similar for both groups. The prevalence of nosocomial pneumonia did not differ significantly between the Peridex group and the Listerine group (4/270 vs 9/291; P = .21). Cultures showed growth more often in the Peridex group than in the Listerine group; again, the difference was not significant (52/270 vs 44/291; P = .19).
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Discussion |
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TopAbstractHypothesisMaterials and MethodsResultsDiscussionReferences |
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The prevalence of cultures showing growth of microorganisms did not differ significantly between the Peridex and the Listerine groups; in fact, the Peridex group had a higher prevalence of cultures showing growth. This result seems counterintuitive to the hypothesis that Peridex could prevent pneumonia by reducing levels of oropharyngeal flora and decreasing aspiration of these microbes. Previous investigators4,5 found that Peridex is more effective than both placebo and Listerine in decreasing levels of oropharyngeal flora. In those studies, actual bacterial counts per milliliter were done. The question of whether quantification by routine sputum culture is a fair indicator of bacterial counts over time is a valid one.
None of the patients extubated within hours of surgery had pneumonia develop. Most of the patients in our study were extubated within hours of surgery. Despite the overall reduction in the prevalence of pneumonia in the Peridex group, because of the low overall pneumonia rate, a large sample size would be required to detect a significant difference in infection rate between the Peridex and the Listerine groups.
Ideally Peridex would be given only to those patients intubated more than 24 hours; however, part of the therapeutic effect is thought to be achieved by decreasing bacterial counts before intubation. Unfortunately, before surgery, there is no way to know for sure which patients will require long-term intubation.
Although the decrease in the overall prevalence of nosocomial pneumonia was not significant, the decrease in the number of patients intubated more than 24 hours who had cultures that showed growth make use of Peridex worth considering for patients undergoing cardiovascular surgery. The costs associated with nosocomial pneumonia in patients undergoing cardiovascular surgery at St. Luke’s were calculated. The estimated cost of using Peridex to try to prevent nosocomial pneumonia in all cardiovascular surgery patients was $700/year. This cost is less than 10% of the cost associated with a single case of nosocomial pneumonia.
Because Peridex is benign, inexpensive, and easy to apply, further research with larger sample sizes is warranted to measure the effects of this therapy.
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ACKNOWLEDGMENTS |
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To purchase reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 809-2273 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, reprints{at}aacn.org.
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REFERENCES |
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