Authors: Maria Carolina Nunes Vilela, Gustavo Zanna Ferreira, Paulo Sérgio da Silva Santos, Nathalie Pepe Medeiros de Rezende
Categories: Review, Chlorhexidine, Evidence-based practice, Intensive care units, Oral hygiene, Pneumonia, ventilator-associated
Source: Einstein
To perform a systematic review of the literature on the control of oral biofilms and the incidence of nosocomial pneumonia, in addition to assessing and classifying studies as to the grade of recommendation and level of evidence. The review was based on PubMed, LILACS, and Scopus databases, from January 1st, 2000 until December 31st, 2012. Studies evaluating oral hygiene care related to nosocomial infections in patients hospitalized in intensive care units were selected according to the inclusion criteria. Full published articles available in English, Spanish, or Portuguese, which approached chemical or mechanical oral hygiene techniques in preventing pneumonia, interventions performed, and their results were included. After analysis, the articles were classified according to level of evidence and grade of recommendation according to the criteria of the Oxford Centre for Evidence-Based Medicine. A total of 297 abstracts were found, 14 of which were full articles that met our criteria. Most articles included a study group with chlorhexidine users and a control group with placebo users for oral hygiene in the prevention of pneumonia. All articles were classified as B in the level of evidence, and 12 articles were classified as 2B and two articles as 2C in grade of recommendation. It was observed that the control of oral biofilm reduces the incidence of nosocomial pneumonia, but the fact that most articles had an intermediate grade of recommendation makes clear the need to conduct randomized controlled trials with minimal bias to establish future guidelines for oral hygiene in intensive care units.
Keywords: Pneumonia, ventilator-associated; Oral hygiene; Chlorhexidine; Intensive care units; Evidence-based practice
Nosocomial infections are among the main causes of mortality in seriously ill patients at Intensive Care Units (ICU), and the most frequent infections are urinary, surgical wounds, and pneumonias.^(^
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The risk of developing nosocomial pneumonia (NP) increases with the use of mechanical ventilation (MV), and besides prolonging, on average, the length of hospital stay for 5 to 9 days, it rises hospital costs.^(^
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The mouth of ICU patients can serve as an important reservoir for respiratory pathogens associated with hospital-acquired pneumonia. These data suggest a new view, in which specific procedures for the control of these oral cavity pathogens should be considered in the prevention of NP.^(^
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Several studies evaluated the efficiency of mouth decontamination in the prevention of nosocomial pneumonia. Two studies did this by means of a systematic literature review, both conducted in 2007,^(^
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^)^ but neither showed the level of scientific evidence or the grade of clinical recommendation. There is a great variety in methods used as to the site of development of the investigations and in intervention methods. Essentially, there are two ways to remove dental plaque and its associated (1) by means of mechanical and/or (2) pharmacological interventions. The need to use one of these methods was made evident when studies demonstrated that 48 hours after admission to the ICU, all the patients presented with oropharyngeal colonization by Gram-negative bacilli, which are frequent etiological agents of nosocomial pneumonia – hence, the biofilm is considered an important pool of respiratory pathogens.^(^
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To perform a systematic review of literature on the control of oral biofilm and the incidence of nosocomial pneumonia, evaluating and classifying the studies as to the grade of recommendation and level of scientific evidence.
Planning of the systematic review sought to clarify the following guiding “can oral hygiene care prevent nosocomial pneumonia in patients under mechanical ventilation at the ICU?”
The selection of articles was done using three databases in the healthcare PubMed, LILACS, and Scopus, from January 1st, 2000, to December 31st, 2012, using the following keywords in English combined among “nosocomial pneumonia”, “pneumonia associated with mechanical ventilation”, “oral care”, “oral hygiene”, and “oral microflora”.
The studies were selected after careful reading of the title and summary in order to verify if they corresponded to the guiding question. After the initial selection, the material was read in full and chosen when it covered all the following inclusion availability of the whole article; published in English; that covered some oral, chemical, or mechanical technique in prevention of pneumonia; and information about the characteristics and methodological rigor, interventions studied, and primary results found. The analysis of the articles was made by two investigators in a blind and independent manner.
The analysis of the data extracted was made descriptively, with no meta-analysis and no statistical analysis. The studies were classified as to the grade of evidence and level of significance, according to the Oxford Centre for Evidence-Based Medicine criteria (Charts 1 and 2).^(^
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Of the 297 summaries first found, 14 articles met the criteria established in this systematic review (Figure 1). Most of the articles included a study group with the use of chlorhexidine and a control group with the use of a placebo. Nine articles concluded that the use of topical chlorhexidine reduced the incidence of NP. Four articles still had not determined statistically significant differences among the groups. Nevertheless, one observed a delay in the establishment of the NP, and another studied toothless patients. As to level of evidence, all the articles were classified as B; as to grade of recommendation, 12 articles were classified as 2B and two articles as 2C (Table 1).
Figure 1 Flow chart of the search strategy
Various aspects compromise mouth hygiene in ICU patients favoring microbial growth, such as difficulty and/or impossibility of self-care, presence of the orotracheal tube, which hinders access to the mouth, and the consequent formation of the biofilm and dental plaque.^(^
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^)^ Thus, mouth decontamination takes on extreme importance in preventing nosocomial pneumonia of patients in the ICU.^(^
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^)^ However, there are many methods used besides the diversity of centers in which the studies are carried out, which makes the adequate interpretation and use of intervention methods difficult.
Chlorhexidine is a wide-spectrum cationic antiseptic agent that includes Gram-negative and Gram*-*positive bacterial, such as oxacillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus sp., which may persist chemically active in tissues for up to 6 hours.^(^
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^)^ In literature, there is a great variety of treatment regimens using chlorhexidine, including variations in 0.12%,^(^
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^)^ No study evaluated in this review performed comparisons correlating the different concentrations of chlorhexidine and the incidence of nosocomial pneumonia. The most studied solution was 0.12% chlorhexidine (7 of 14 studies), and in some articles, it served as control for another method of evaluation.^(^
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^)^ The 2% concentration was the most effective in preventing NP, but only two studies evaluated this concentration – one of them, as study with a 2C level of recommendation.
Some articles compared isolated chemical removal using 0.12% chlorhexidine, and associated with mechanical removal using an electric and manual toothbrush.^(^
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^)^ The results of the addition of dental brushing were not significant for the prevention of MV-associated pneumonia. Tooth brushing alone did not reduce pneumonia associated with mechanical ventilation; the combination of brushing with chlorhexidine also showed no additional benefits when compared to the use of chlorhexidine alone. Additionally, during brushing, dislocation of the dental plaque may occur, supplying a large number of microorganisms translocated from the mouth to the subglottic secretions of the lungs, contraindicating the mechanical removal of bacterial plaque with dental brushes, with recommendation only for chemical removal with 0.12% chlorhexidine.^(^
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The diversity of patients and of ICUs is an important factor that should be considered in the analysis of NP incidence, taking into consideration the type of ICU and the profile of the patients. The percentage of NP varied from a minimum of 7% in a group that used mechanical brushing to control biofilm^(^
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^)^ A reduction superior to 40% in incidence of pneumonia was found in five studies,^(^
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The control of oral biofilm reduces the incidence of nosocomial pneumonia. Oral hygiene using a 0.12% solution of chlorhexidine, and not dental brushing, seems to be the most effective hygiene method. This concentration of chlorhexidine does not harm the oral mucosa and no dislocation of the dental biofilm towards the posterior oropharynx occurs when mechanical brushing is done.
The fact that most of the articles presented an intermediate B and 2B level of evidence and grade of recommendation, respectively, makes clear the need for conducting randomized controlled clinical trials with a minimal bias, due to the need for intensive care services having at their disposal valid protocols for the effective application of oral care and consequent reduction of nosocomial pneumonia.