The effectiveness of perioperative oral hygiene in reduction of postoperative respiratory tract infections after thoracic surgery in adults: a systematic review.

Review question/objective The objective of this systematic review is to identify, appraise and synthesise the best available evidence on the effectiveness of systematic perioperative oral hygiene in reduction of post-operative respiratory airway infections in adult patients undergoing elective thoracic surgery. More specifically, the review question is: What is the effectiveness of perioperative systematic oral hygiene compared to patients' usual oral hygiene in reduction of postoperative upper or lower respiratory tract infections in adult patients undergoing elective thoracic surgery? Background Nosocomial infections (NI) are a significant contributor to patient morbidity and mortality. NI significantly increases hospital length of stay and total hospital cost.1 Thoracic surgery, mechanical ventilation and/or admission to an intensive care unit (ICU) are known to increase patients' risk for nosocomial respiratory tract infection.2,3 Most NIs acquired following thoracic surgery affect the respiratory tract.4 So, even if the operation is performed well, the patients who experience postoperative infections have a higher risk of postoperative prolonged recovery or higher risk of mortality. Incidence of respiratory tract infection after thoracic surgery A cross-sectional study 4 from Europe including 42 institutions in 13 countries examining the infections rate after major heart surgery found that the overall prevalence of infections was 26.8%. Lower respiratory tract infections represented 57% of all infections present on the study day.3 Nosocomial pneumonia accounts for approximately 10% to 15% of all hospital-acquired infections, and 20% to 50% of affected patients will die because of the infection.5 Incidence rates of up to 20% have been reported for nosocomial infection after cardiac surgery4, 6; nosocomial induced respiratory tract infections count for more than 50% of the nosocomial infections in this patient group4 leading to increased need for antimicrobial therapy, prolonged recovery and higher concomitant costs. 4 The prognosis of oesophageal cancer is improving, but problems with postoperative infections need to be solved, as postoperative pneumonia occurs in up to 32% of the patients and pneumonia is associated with an increased risk of mortality. 7, 8 Nosocomial pneumonia A systematic review concludes that there is fair evidence of an association of pneumonia with oral health and that there is good evidence that improved oral hygiene and frequent professional oral health care reduces the prognosis or occurrence of respiratory diseases among high-risk elderly adults living in nursing homes and especially those in intensive care units.9 The Centre of Disease Control and Prevention 10 describes four mechanisms that lead to nosocomial pneumonia: 1) aspiration of oropharyngal organisms, 2) inhalation of aerosol that contains bacteria, 3) haematogenous spread from distant body sites, and 4) bacterial translocation from the gastrointestinal tract. Aspiration of organisms from oropharynx is generally considered the most important of these mechanisms.10, 2 Aspiration of material from the upper airways occurs in 45% of healthy subjects during sleep and in 70% of subjects with impaired consciousness.5 Colonisation of the host by potentially pathogenic microorganisms is a prerequisite for the development of nosocomial infections. Although potentially pathogenic microorganisms can be transmitted to patients from the hands of health care workers and contaminated equipment, the patient's own flora is the primary source.5, 11 Colonisation of dental plaque by Gram-negative bacteria has been recognised as an important contributor to the oropharyngeal bacterial pool. In healthy individuals, mechanical cleansing of teeth and gums plays an important role in preventing plaque and biofilm formation.12 In critically ill patients, lack of spontaneous movement of the tongue and jaws, infrequent swallowing, and inability to brush teeth because of orotracheal intubation or altered mental status can result in formation of a biofilm or plaque as early as 24 hours after ICU admission. 12 This complex microhabitat of interdependent organisms enmeshed in bacterial and salivary products has been demonstrated to be a reservoir of respiratory pathogens,5, 12 and therefore a source of infection. Pathogens in preoperative dental plaque are known risk factors for postoperative pneumonia following thoracotomy.13 Furthermore, patients who undergo an oesophagectomy have a risk of paralysis of the recurrent pharyngeal nerve, which predisposes them to the postoperative passage of oral contents into the trachea, and subsequent aspiration of oral bacteria into the upper respiratory tract.8 Strategies to reduce nosocomial infections Considerable efforts have been made to reduce the occurrence of nosocomial infections. One strategy involves use of selective decontamination of the digestive tract, through antimicrobial therapy to eradicate potentially pathogenic microorganisms from the oropharynx, stomach, and gut.6 Another important strategy involves the eradication of Staphylococcus aureus, the most important pathogen responsible for surgical site infections (SSIs), by the application of topical antimicrobials.8 One such agent, mupirocin, is a cornerstone of treatment of methicillin-resistant staphylococcus aureus (MRSA) colonisation. Therefore, widespread use of mupirocin for other purposes is not desirable because of the concern of rising resistance rates.6 The first study10 with selective decontamination of the oral cavity by systematic cleansing of the teeth and use of oral rinse, chlorhexidine gluconate, was published in 1996 and have been show to kill or disrupt oral biofilms after a single exposure of antimicrobial mouth rinse and toothpastes and that antimicrobials is absorbed in dead biofilms and hereby exert prolonged actions on organisms growing from fresh saliva on top of the dead biofilms.14 This strategy has been successful in reducing ventilator associated pneumonia (VAP) in ICU patients and in patients in long term facilities.9, 14, 15 Some studies16 suggest that this strategy will reduce the incidence of post-operative respiratory tract infections in patients undergoing elective thoracic surgery as well.2, 8 An initial search in the databases CINAHL, JBI COnNECT+, DARE, PubMed, Cochrane Library and PROSPERO shows that no systematic review on this topic exist, or is currently underway. Definitions For the purposes of this review, the following definitions will be used: Elective surgery: surgery that is subject to choice (election), made either by the patient or doctor and is beneficial to the patient but does not need to be done at a particular time, in contrast to emergency surgery.17 Thoracic surgery: a process to treat diseased or injured organs in the thorax, including the oesophagus, trachea, pleura, mediastinum, chest wall, diaphragm, heart, and lungs. 17 Postoperative complications: pathologic processes that affect patients after surgery. Postoperative complications may (or may not) be directly related to the disease for which the surgery was done or to the surgery itself. 3 Nosocomial infections: infection as a localised or systemic condition that: 1) results from adverse reaction to the presence of an infectious agent(s) or its toxin(s), and 2) was not present or incubating at the time of admission to the hospital. For most bacterial nosocomial infections, this means that the infection usually becomes evident 48 hours (i.e., the typical incubation period) or more after admission. 8 Inclusion criteria Types of participants This review will consider studies that include patients over the age of 18 years who have been admitted for elective thoracic surgery, regardless of gender, ethnicity, diagnosis severity, comorbidity or previous treatment. The reasons for surgery will include, but not be limited to: elective or acute Coronary Artery By-pass Grafting, (CABG), coronary valve surgery, any type of lung surgery or surgery for oesophageal cancer. Patients undergoing emergency thoracic surgery are outside the scope of the review and will therefore be excluded. Types of interventions and comparators This review will consider studies that evaluate perioperative systematic oral hygiene such as mechanical removal of dental biofilm or plaques and/or systematic use of mouth rinse. This oral hygiene may be performed by patients themselves or by healthcare staff (such as nurses). Tooth brushing interventions: Mechanical plaque control is the removal of microbial plaque and the prevention of accumulation on the teeth and adjacent gingival surface by the use of toothbrush and other mechanical hygiene aids without the use of chemical. Patients following a particular protocol for their tooth brushing for up to seven days before the surgical procedure will be considered for this review. The intervention may specify the frequency of tooth brushing that the patients are instructed to perform each day, the use of a specific method for brushing the teeth or the use of a specific toothpaste for the procedure. Comparator: Usual care as defined by the included papers, however it is anticipated that patients follow no particular protocol for their tooth brushing for up to seven days before the surgical procedure. Oropharyngeal mouthwash interventions: A typical therapeutic mouth rinse may contain sodium fluoride, glycerine, alcohol, detergents, and other ingredients. Some mouth rinses only remove loose debris and add a fragrance to mask mouth odours. Patients following a specified mouth wash intervention (e.g. oropharyngeal rinse containing either chlorhexidine gluconate (0.12%)) will be considered for inclusion in this review. The oropharyngeal solution (10 mL) must be used as a mouth rinse and applied to buccal, pharyngeal, gingival, and tooth surfaces for 30 seconds at least twice daily. The intervention must start at least one day before surgery and continue until one day after surgery or discharge from ICU. If the patient is unable to follow the protocol independently, a member of the health care team must perform the procedures for the patient. Comparator: It is anticipated that the effectiveness of mouth rinses will be compared with usual care or a placebo mouth rinse. Types of outcomes This review will only consider studies that include the following outcome measures as defined by The Centre of Disease Control and Prevention3: Any respiratory tract infection (RTI) occurring during hospital stay or within 48 hours after discharge will be considered an infection related to the surgical procedure. 3, 8 Lower respiratory tract infection: Patients are classified as having a lower respiratory tract infection (or bacterial pneumonia) if they have a new or progressing pulmonary infiltrate, fever, leukocytosis, and purulent tracheobronchial secretions. 3,10 Upper respiratory tract infect ion: Patients are classified as having an upper respiratory tract infection (or acute purulent tracheobronchitis) if they have all the criteria for pneumonia, but do not have a new or progressing infiltrate on chest radiograph. 10 Surgical site infection (SSI) is defined as a wound defect in which infection is present beneath the subcutaneous layers; for example, in the mediastinal region with or without sternal involvement. 8 Types of studies This review will consider any experimental study design including randomised controlled trials, non-randomised controlled trials, quasi-experimental, and before and after studies for inclusion. Search strategy The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilised in this review. An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. The initial search terms have been chosen in discussion with a research librarian with the aim of identifying the maximum number of articles possible. A second search using all identified keywords and index terms will then be undertaken across all included databases. Thirdly, the reference list of all identified reports and articles will be searched for additional studies as well as citation searches will be applied. Studies published in English, German, Danish, Swedish and Norwegian will be considered for inclusion in this review. Databases will be searched from their inception to June 2012. The databases to be searched include: PubMed, CINAHL, Embase, Scopus, Swemed+, Health technology assessment database, Turning Research Into Practice (TRIP) database Additional searching for published literature will include: Hand searching reference lists and bibliographies of included articles and any relevant systematic reviews identified in the Joanna Briggs Institute Library of Systematic Reviews and Cochrane Database of Systematic Reviews. The search for unpublished studies will include: Conducting an online search of databases and websites including: - MedNar - Proquest Dissertations and Theses (for international dissertations and theses) - National Institutes of Health (NIH) Clinical Trials Databases (Host: NIH(http//clinicaltrials.gov)) - College of Nurses of Ontario (http://www.cno.org/learn-about-standards-guidelines) Initial keywords/search terms to be used will be: Dental hygiene or oral hygiene or mouth hygiene or oral care or toothbrushor or mouthwashes or gels or chlorhexidine or chlorhexidine gluconateor or mouth rinse or tooth paste or local decontamination or anti-bacterial agents AND Surgery or Cardiac surgery or Thoracic surgery or Heart surgery or Cardiac Surgical Procedures thoracic surgery or lung surgery or esophageal/oesophageal surgery or thoracotomy AND Postoperative complication or prevention or nosocomial infection or surgical site infectionor or pneumonia or respiratory tract infection or surgical wound infection or respiratory airway infection or cross-infection Assessment of methodological quality Papers selected for retrieval will be assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardised critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix I). Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer. Data collection Data will be extracted from papers included in the review using the standardised data extraction tool from JBI-MAStARI (Appendix II). The data extracted will include specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. Data synthesis Quantitative data will, where possible, be pooled in statistical meta-analysis using JBI-MAStARI. All results will be subject to double data entry. Effect sizes expressed as odds ratio for categorical data and their 95% confidence intervals will be calculated for analysis. Heterogeneity will be assessed statistically using the standard Chi-square. Where statistical pooling is not possible, the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate. Conflicts of interest None identified. Acknowledgements None.

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