prevenção de pneumonia associada à ventilação mecânica : revisão integrativa Strategies for preventing ventilator-associated pneumonia : an integrative review

Objective: to identify studies about strategies for prevention of ventilator-associated pneumonia deployed in health services and classify their level of evidence. Method: integrative review of the literature, in 7 databases, which included the following descriptors: Prevention and Control AND Pneumonia Ventilator-Associated AND Intensive Care Units AND Bundle AND Patient Care. Results: twenty-three scientific productions were included. Of the preventive measures identified, 9 (39.1%) correspond from three to five strategies. The most frequent were: 22 (95.6%) lying with head elevated, 19 (82.6%) oral hygiene with chlorhexidine and 14 (60.8%) reduction of sedation whenever possible. Final Consideration: the application of measures based on scientific evidence is proven to be effective when carried out in conjunction, impacting the reduction of the incidence of ventilator-associated pneumonia. Descriptors: Disease Prevention; Ventilator-Associated Pneumonia; Patient Care Bundles; Intensive Care Unit; Nursing. RESUMEN Objetivo: identificar estudios sobre estrategias de prevención de neumonía asociadas a la ventilación mecánica implantadas en servicios de salud y clasificar el nivel de evidencia de los mismos. Método: revisión integrativa de la literatura, en 7 bases de datos, que incluyó los siguientes descriptores: Prevention and Control AND Pneumonia Ventilator-Associated AND Intensive Care Units AND Bundle AND Patient Care. Resultados: Se incluyeron 23 producciones científicas. Entre los conjuntos de medidas de prevención identificados, 9 (39,1%) contemplan entre tres a cinco estrategias. Fueron las más frecuentes: el decúbito elevado, 22 (95,6%); la higiene oral con clorhexidina, 19 (82,6%); y la reducción de la sedación siempre que sea posible, 14 (60,8%). Consideraciones Finales: La aplicación de medidas basadas en evidencias científicas es comprobadamente eficaz cuando se aplica en conjunto, impactando en la reducción de la densidad de incidencia de neumonía asociada a la ventilación mecánica. Descriptores: Prevención de Enfermedades; Neumonía Asociada al Ventilador; Paquetes de Atención al Paciente; Unidades de Cuidados Intensivos; Enfermería. Estratégias para prevenção de pneumonia associada à ventilação mecânica: revisão integrativa Strategies for preventing ventilator-associated pneumonia: an integrative review Estrategias para la prevención de la neumonía asociada a la ventilación mecánica: revisión integrativa REVISÃO Raimunda Xavier AlecrimI ORCID: 0000-0002-7775-5853


INTRODUCTION
Healthcare-associated infections (HAI) are serious adverse events that affect hospitalized patients, mostly in the intensive care unit (ICU).Among them, ventilator-associated pneumonia (VAP) stands out, being defined by the Brazilian National Health Surveillance Agency (ANVISA) as pneumonia associated with clinical, radiological and laboratory criteria evidenced 48 hours after the start of mechanical ventilation (MV) (2) .
In the United States of America (USA), about 300,000 patients are submitted to MV every year and, despite the efforts to reduce the incidence of VAP, its density still remains around 4.4 cases/1,000 MV-day (1) .
According to the System of Surveillance of Hospital Infections of the State of São Paulo, the density of VAP incidence in the state's ICUs in 2017 was 7.69/1000 MV-day for ICUs with more than 500 patients/day in public hospitals and 9.63/1000 MV-day in university hospitals (4) .General mortality attributed to VAP varies considerably, reaching rates from 20% to 60% (5) .
A successful strategy in the control of HAI refers to the adoption of intervention or best-practice bundles.The methodology of the bundle strategy requires the implementation of interventions in conjunction, as this practice has been proved to be more effective than the application of isolated measures (6) .
In this context, following the example of international organizations, ANVISA has been recommending the adoption of bundles for prevention of VAP, considering its impact on healthcare and the reduction in infection rates, with the assumption that the choice of interventions considers their cost, ease of deployment and adherence (5,7) .
The interventions regarded as best practices and the extensive literature published in recent years on the subject, with various levels of evidence, led to the conduction of this integrative literature review, with the objective to organize the studies according to level of evidence to make them more accessible to professionals, motivating the implementation of strategies that promote the adherence to best practices in the prevention of VAP.Awareness about the magnitude of HAI and their influence on health outcomes as well as access to the evidence available have the potential to motivate behavior changes among professionals, with impacts on the process and outcome indicators.

OBJECTIVE
To identify studies about strategies for prevention of ventilatorassociated pneumonia deployed in health services and classify their level of evidence.

METHOD
Integrative literature review carried out in the period from April to September 2017.The research question was chosen based on the PICO strategy (patient, intervention, comparison and outcomes), where: P: ventilator-associated pneumonia; I: VAP prevention strategies; C: comparison of the VAP prevention strategies; O: reduction in the incidence of VAP.
Six steps recommended for this type of review were applied: 1) Identification of the theme and selection of the hypothesis or research question; 2) Establishment of criteria for inclusion and exclusion of studies/sampling or search in the literature; 3) Definition of the information to be extracted from the selected studies/categorization of studies; 4) Evaluation of the studies included in the integrative review; 5) Interpretation of results and 6) Presentation of the review/summary of knowledge (8) .
The databases consulted were: Scientific Electronic Library Online (SCIELO), U.S. National Library of Medicine (PUBMED), Medical Literature Analysis and Retrieval System Online (MEDLINE), The Cochrane Library (Cochrane).The following databases were accessed through the Virtual Health Library (VHL): Latin American and Caribbean Center on Health Sciencies Information (LILACS), Brazilian Nursing Database (BDENF) and Spanish Bibliographic Index of Health Sciences (IBECS).
To perform the search of scientific productions, the following descriptors were used in English in the seven databases: Prevention and Control AND Pneumonia Ventilator-Associated AND Intensive Care Units AND Bundle AND Patient Care.
The inclusion criteria were: researches conducted with human beings, productions in English, Portuguese and Spanish, full texts available for access without delimitation of date of publication.The work's relevance in relation to the research question was determined through the reading of the studies' titles and abstracts, and those that had their adequacy to the topic of interest ascertained were evaluated through a content analysis and classified according to level of evidence (9) .Duplicate publications and those that were not aligned with the inclusion criteria were excluded, as well as studies with animals and children.Figure 1 shows the flowchart of the selection and identification of studies.In total, 23 scientific productions were included in the review.The results were organized and will be presented in the form of a table containing a synthesis of the information extracted from the articles.
The steps of selection are presented in figure form, being organized as follows: 1st selection: search by descriptors; 2nd selection: selection of inclusion criteria; 3rd selection: reading of titles and abstracts and 4th selection: reading of the article in full.366 articles were identified in the search 32 articles were selected 23 articles were selected and included in this study 334 articles were excluded after their abstract had been read and the inclusion criteria analyzed 9 articles were excluded after being read in full Figure 1 -Flowchart of the selection and identification of studies according to the PRISMA recommendations (10) Strategies for preventing ventilator-associated pneumonia: an integrative review Alecrim RX, Taminato M, Belasco A, Longo MCB, Kusahara DM, Fram D.

RESULTS
Using the methodology employed for the literature review, 23 articles published between 2007 and 2016 were selected, 15 (65.2%) with foreign origins and 08 (34.7%) having been produced in Brazil.Table 1 presents the summary of the articles selected for the study by ascending chronological order of publication:

Overall evaluation of the studies
In relation to objectives, all 23 studies (100%) assessed the impact of different interventions on the occurrence of VAP..

To determine the effectiveness of isolated interventions in VAP incidence;
To determine the effectiveness of at least two interventions for reduction of the VAP rates.

Observational study/ III
Elevation of the headboard.Daily awakening from sedation.Prevention of stress ulcer.

Prevention of deep vein thrombosis
The average VAP rate was 2.7 cases/1000 MV-day.Among the units, 39% reported adequate adherence to the intervention bundle.
To analyze the impact of a multimodal approach for reduction of VAP in 3 ICUs of a Chinese hospital.
To assess the impact of some preventive measures that were already part of the routine of ICUs in  (31) .
To assess the impact of the bundle, the determining factors that influence compliance with the VAP prevention measures in an ICU, the profile of microorganisms and mortality rate.Only 4 (7.3%)studies included the assessment of conformity with the bundles' measures, two (8.69%) evaluated the measures' influence on MV days, one (4.34%)study evaluated the length of stay in the ICU, and one (4.34%)evaluated the expenditure on antimicrobials and mortality.
Of the 23 scientific productions selected, 9 (39.1%)included intervention bundles as proposed by the Institute for Healthcare Improvement (IHI), which advocates the joint implementation of three to five interventions with high level of evidence.The other productions feature intervention check lists.
When analyzing the interventions proposed in the studies, we can identify lying with head elevated between 30° and 45° in 22 (95.6%),oral hygiene with chlorhexidine in 19 (82.6%), and sedation weaning whenever possible or daily awakening from sedation in 14 (60.8%) of them.
Hand hygiene, prophylaxis for gastric ulcer and prophylaxis for deep vein thrombosis were mentioned in 11 (47.8%) of the articles.In lower frequency than the others, maintenance of cuff pressure was reported in 10 (43.4%), general care with ventilation circuits, including their replacement only if visibly dirty, in 8 (34.7%), and subglottic aspiration in 5 (21.7%) of the studies as VAP prevention measures.For the researches that assessed the rate of compliance with the bundle's elements, it was found that the lower the adherence to them, the less impact they had on the reduction of VAP rates.Adherence rates higher than 90% were significantly associated with the reduction in VAP rates.Maintaining adherence to the measures in the long term contributed to reaching VAP rates close to zero.
The two studies that evaluated the bundle's effect on MV time found discrepant results.One of them showed an increase in MV days despite the reduction in VAP rates, while the other showed reduction in MV days.Additionally, the studies that assessed the expenditure on antimicrobials and mortality rates showed favorable results.
Among all the studies that compared the VAP rates before and after the implementation of the set of measures, 20 (86.9%) showed positive results, 1 (4.34%) did not identify significant improvements, 1 (4.34%) reported similar rates in the two stages and 1 (4.34%) revealed an increase in the VAP rates after implementation of the bundle, related to lack of equipment and inputs needed for the provision of care, in addition to the turnover of professionals that happened in this period, as the newcomers had no adequate training.
Of the 23 (100%) researches included in the review, 20 (86.9%) of them reported the importance of health professionals knowing the VAP rates of their services, receiving guidance and feedback on the conformity of the VAP prevention measures and practicing the continuous surveillance of these measures for the maintenance of the low density of VAP incidence.Through the association of these strategies with the implementation of best practices, it is possible to reduce VAP incidence by up to 90%, when the proposed measures are followed properly.

DISCUSSION
Although significant progress has occurred with regard to the implementation of the best practices for the prevention of HAI, efforts must be made to reduce their frequency.The World Health Organization recommends that national and regional authorities develop actions for reduction of HAI, through the engagement between public health agencies, healthcare professionals and local institutions for the implementation, sustainability and expansion of a program of surveillance and prevention of HAI (34) .
In the prevention and control of VAP, listing priorities is crucial.Monitoring the adherence to best practices, education, and establishment of process, structure and outcome indicators is essential for further reducing its incidence.In ICUs, it is relevant to carry out VAP surveillance with standardized definitions and criteria, as well as calculate the VAP rates, report these rates to the health team and, above all, associate them with the relevant preventive measures.These actions can become an important ally in the evaluation of the quality of care (5) .
To this end, surveillance should be carried out by a trained team with defined epidemiology concepts and criteria, through the development of educational strategies, which should preferably be multimodal and evidence-based.Most of the researches identified in the review featured evidence level II and III, which correspond to evidence derived from non-randomized clinical trials and well-delineated cohort and case-control studies.The adoption of recommendations from studies with this level of evidence has the potential for reduction of the density of VAP incidence, hospital costs, MV days and mortality rates (35)(36)(37) .
To assess the impact of a VAP prevention bundle called fasthug on costs and VAP-related mortality rates in an ICU.However, it should be noted that the indication of some interventions present in these studies does not derive from randomized clinical trials, classified as evidence level I, which could provide missing information about VAP prevention.
Still, it is essential to maintain a routine of multidisciplinary visits with participation of the professionals directly involved in the care to patients using MV, promoting the identification of non-compliance with healthcare processes, assisting the management of preventive measures and facilitating the relationship between professionals (5) .
Hand hygiene, a recommended measure with proven impacts on HAS prevention, including VAP, was present in 47.8% of the bundles identified; however, adherence to this action remains below the expected among professionals.
According to the Brazilian National Program for Prevention and Control of Healthcare-Associated Infections, which sets targets for the reduction of HAS, the VAP prevention protocol must contain at least guidelines to keep the headboard of the patients' beds elevated between 30° and 45°; evaluate daily sedation and reduce it where possible; and carry out oral hygiene with antiseptics.Most of the studies included in the review adopted actions that are strongly recommended by Anvisa; however, non-compliance with all of the proposed measures was identified in 60.8% of them (34) .
Other recommendations of international agencies, like CDC, have also been reported in the studies, such as maintenance of the suction system, enteral diet, use of passive humidifiers, appropriate processing of ventilatory assistance products, use of sterile water for procedures, proper handling of inhalers and nebulizers, among others (1,38) .
Researches for evaluation of specific measures, such as proper handling of ventilation circuits and secretions, early extubation protocol and the patient's positioning at 45°, have shown significant reduction in VAP incidence (35)(36)39) .
Other strategies described in the VAP control studies included prophylaxis for deep vein thrombosis and gastric ulcer, indication for cautious use of neuromuscular blockers, adoption of non-invasive MV and prevention of accidental extubation and reintubation (5) .
Constant staff turnover, lack of training, lack of knowledge about the density of VAP incidence, lack of supplies and poor structure are determining factors for the failure of preventive measures.In this context, the need for permanent education of the team is emphasized, with the purpose of promoting the adherence to the protocol and preventing VAP, reducing its rates (40) .
Within the perspective of transformation of practice, permanent education of the staff is an indispensable component for the achievement of the desired changes and for improving the quality of the service provided.The challenge of promoting VAP prevention is directly related to the modification of the behavior of healthcare professionals.This behavior change involves aspects related to the environment, context, knowledge, beliefs and social influences.Evaluating the individual's behavior highlights particularities that, when addressed, can contribute to a change that is more evident and sustained.

Study limitations
The limitation of this study refers to the fact that it has not been possible to integrate research findings that compare interventions for VAP prevention, due to shortage of clinical trials and variability of the methodology used in the studies.

Contributions to the field of nursing, health or public policy
Healthcare-related infections, like VAP, are important adverse events which compromise patient safety.Despite all efforts for the prevention of these infections, their prevalence remains high, mainly due to the low adherence to the scientifically proven measures intended for this purpose.
Most of the specific interventions for VAP prevention directly involve the nurse's performance, be it in their implementation, surveillance or management.This makes the nursing staff essential to the implementation of preventive and educational strategies.The compilation of current researches on the subject, made possible by literature reviews, facilitates and makes the information more accessible to professionals who participate in health-related practices and decision-making processes.Once they have acquired this knowledge, they become more likely to change behaviors and gain motivation for the adoption of HAS prevention measures, consequently reducing the morbidity and mortality caused by this event.

FINAL CONSIDERATIONS
VAP can result in serious repercussions for patients affected by this condition, and features a large impact on morbidity and mortality rates, MV time, length of stay in the ICU and increase in welfare costs.Given this, the selection and application of evidence-based measures which are appropriate for each health service, based on the individual needs of patients, is fundamental, seeing as these measures, arguably, when applied collectively, decrease the density of VAP incidence, this being one of the most frequent healthcare-related infections in intensive care units.