Cuidados de enfermagem na prevenção da pneumonia associada à ventilação mecânica / Nursing care in preventing pneumonia associated with mechanical ventilationt / Atención de enfermería en la prevención de la neumonía associada a la ventilación mecânica

Introdução:A ventilação mecânica invasiva é um recurso terapêutico artificial, que possui a finalidade de equilíbrio da ventilação e/ou oxigenação de pacientes com insuficiência respiratória, entre as complicações desta intervenção, destaca-se a pneumonia. Nesse âmbito, o enfermeiro tem um papel primordial na criação de programas de prevenção das infecções, sobretudo na precaução da pneumonia associada à ventilação mecânica nas unidades de terapia intensiva. Objetivo:Descrever as ações de enfermagem para prevenção da pneumonia associada à ventilação mecânica invasiva na Unidade de Terapia Intensiva. Metodologia:Trata-se de um estudo do tipo revisão integrativa da literatura, para qual, definiu-se como ambiente de pesquisa as bases de dados BDENF, LILACS e MEDLINE. Elencou-se artigos publicados nos idiomas português, inglês e espanhol no período entre 2015 a 2019. Explorou-se os artigos a partir dos parâmetros estabelecidos pelo guia PRISMA, verificação dos títulos, resumos e texto completo, considerando os estudos que estivessem de acordo com o objetivo proposto, sendo selecionados 7 artigos para compor esta revisão. Resultados:Observou-se nos artigos analisadosa importância da adesão de ferramentas de ações no processo de cuidado, como os protocolos e bundles (um conjunto de medidas e intervenções) de prevenção da pneumonia associada à ventilação mecânica, para quais compreendem práticas como a verificação da pressão do cuff, elevação da cabeceira, aspiração de secreção, higiene oral, validade dos artigos médicos, lavagens das mãos e a interrupção da infusão de sedativos. Conclusões:Preconiza-se a adesão de medidas preventivas da pneumonia associada à ventilação mecânica nas unidades de terapia intensiva, as quais precisam ser praticadas rigorosamente pelos profissionais de enfermagem, por serem representantes do cuidado. Ressalta-se a necessidade de atualizações e construções de protocolos com medidas que possam prevenir as infecções de trato respiratório oriundas do uso da ventilação mecânica invasiva (AU).

Introduction:Invasive mechanical ventilation is an artificial therapeutic resource, which aims to balance ventilation and / or oxygenation of patients with respiratory failure, among the complications of this intervention, pneumonia stands out. In this context, the nurse has a primary role in creating infection prevention programs, especially in the prevention of pneumonia associated with mechanical ventilation in intensive care units. Objective:To describe nursing actions to prevent pneumonia associated with invasivemechanical ventilation in the Intensive Care Unit.Methodology:This is a bibliographic study, of the type integrative literature review, for which the databases BDENF, LILACS and MEDLINE were defined as a research environment. Articles published in Portuguese, English and Spanish from 2015 to 2019 were listed. Articles were explored using the parameters established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guide, verification of titles, abstracts and full text, considering studies that were in accordance with the proposed objective, with 7 articles selected to compose this review. Results: It was observed in the analyzed articles the importance of adhering to action tools in the care process, such as protocols and bundles (a set of measures and interventions) for preventing pneumonia associated with mechanical ventilation, for which they comprise practices such as checking the cuff pressure, elevating the headboard, secretion aspiration , oral hygiene, validity of medical articles, hand washing and stopping the infusion of sedatives. Conclusions:Adherence to preventive measures for pneumonia associated with mechanical ventilation in intensive care units is recommended, which must be strictly practiced by nursing professionals, as they are representatives of care. The need to update and build protocols with measures that can prevent respiratory tract infections arising from the use of invasive mechanical ventilation is emphasized (AU).

Introducción:La ventilación mecánica invasiva es un recurso terapéutico artificial, con la finalidad de equilibrar la ventilación y / u oxigenación enpacientes con insuficiencia respiratoria, entre las complicaciones de esta intervención se destaca la neumonía. En este contexto, la enfermera es fundamental en la creación de programas de prevención de infecciones, especialmente en neumonía asociada a ventilador en unidades de cuidados intensivos. Objetivo:Describir las acciones de enfermería para prevenir la neumonía asociada a la ventilación mecánica invasiva en la Unidad de Cuidados Intensivos. Metodología:Se trata de una revisión integradora de la literatura, realizada a través de las bases de datos BDENF, LILACS y MEDLINE. Se enumeraron los artículos publicados en portugués, inglés y español en el período comprendido entre 2015 y 2019. Los artículos fueron explorados en base a los parámetros establecidos por la guía Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA), verificación de títulos, resúmenes y texto completo.,considerando los estudios que estaban de acuerdo con el objetivo propuesto, seleccionándose 7 artículos. Resultados:Se observó la importancia de la adherencia a herramientas de acción en el proceso de atención, como protocolos y paquetes (conjunto de medidas e intervenciones) para la prevención de la neumonía asociada al ventilador, que incluyen prácticas comoel control de la presión del paciente. manguito, elevación de la cabeza, aspiración de secreciones, higiene bucal, vigencia de artículos médicos, lavado de manos e interrupción de la infusión de sedantes. Conclusiones:Se recomienda la adherencia a las medidas preventivas, las cuales deben ser practicadas con rigor por los profesionales de enfermería, por ser representantes del cuidado. Se destaca la necesidad de actualización y construcción de protocolos con medidas que puedan prevenir las infecciones deltracto respiratorio derivadas del uso de ventilación mecánica invasiva (AU).

Mechanical ventilation enhances Acinetobacter baumannii-induced lung injury through JNK pathways.

BACKGROUND: Patients in intensive care units (ICUs) often received broad-spectrum antibiotic treatment and Acinetobacter baumannii (A.b.) and Pseudomonas aeruginosa (P.a.) were the most common pathogens causing ventilator-associated pneumonia (VAP). This study aimed to examine the effects and mechanism of mechanical ventilation (MV) on A.b.-induced lung injury and the involvement of alveolar macrophages (AMs). METHODS: C57BL/6 wild-type (WT) and c-Jun N-terminal kinase knockout (JNK1-/-) mice received MV for 3 h at 2 days after nasal instillation of A.b., P.a. (1 × 106 colony-forming unit, CFU), or normal saline. RESULTS: Intranasal instillation of 106 CFU A.b. in C57BL/6 mice induced a significant increase in total cells and protein levels in the bronchoalveolar lavage fluid (BALF) and neutrophil infiltration in the lungs. MV after A.b. instillation increases neutrophil infiltration, interleukin (IL)-6 and vascular cell adhesion molecule (VCAM) mRNA expression in the lungs and total cells, IL-6 levels, and nitrite levels in the BALF. The killing activity of AMs against A.b. was lower than against P.a. The diminished killing activity was parallel with decreased tumor necrosis factor-α production by AMs compared with A.b. Inducible nitric oxide synthase inhibitor, S-methylisothiourea, decreased the total cell number in BALF on mice receiving A.b. instillation and ventilation. Moreover, MV decreased the A.b. and P.a. killing activity of AMs. MV after A.b. instillation induced less total cells in the BALF and nitrite production in the serum of JNK1-/- mice than those of WT mice. CONCLUSION: A.b. is potent in inducing neutrophil infiltration in the lungs and total protein in the BALF. MV enhances A.b.-induced lung injury through an increase in the expression of VCAM and IL-6 levels in the BALF and a decrease in the bacteria-killing activity of AMs. A lower inflammation level in JNK1-/- mice indicates that A.b.-induced VAP causes lung injury through JNK signaling pathway in the lungs.

Pulmonary Aspergillosis in Patients with Suspected Ventilator-associated Pneumonia in UK ICUs.

Rationale:Aspergillus infection in patients with suspected ventilator-associated pneumonia remains uncharacterized because of the absence of a disease definition and limited access to sensitive diagnostic tests.Objectives: To estimate the prevalence and outcomes of Aspergillus infection in adults with suspected ventilator-associated pneumonia.Methods: Two prospective UK studies recruited 360 critically ill adults with new or worsening alveolar shadowing on chest X-ray and clinical/hematological parameters supporting suspected ventilator-associated pneumonia. Stored serum and BAL fluid were available from 194 nonneutropenic patients and underwent mycological testing. Patients were categorized as having probable Aspergillus infection using a definition comprising clinical, radiological, and mycological criteria. Mycological criteria included positive histology or microscopy, positive BAL fluid culture, galactomannan optical index of 1 or more in BAL fluid or 0.5 or more in serum.Measurements and Main Results: Of 194 patients evaluated, 24 met the definition of probable Aspergillus infection, giving an estimated prevalence of 12.4% (95% confidence interval, 8.1-17.8). All 24 patients had positive galactomannan in serum (n = 4), BAL fluid (n = 16), or both (n = 4); three patients cultured Aspergillus sp. in BAL fluid. Patients with probable Aspergillus infection had a significantly longer median duration of critical care stay (25.5 vs. 15.5 d, P = 0.02). ICU mortality was numerically higher in this group, although this was not statistically significant (33.3% vs. 22.8%; P = 0.23).Conclusions: The estimated prevalence for probable Aspergillus infection in this geographically dispersed multicenter UK cohort indicates that this condition should be considered when investigating patients with suspected ventilator-associated pneumonia, including patient groups not previously recognized to be at high risk of aspergillosis.

The predictive value of procalcitonin in ventilator-associated pneumonia after cardiac valve replacement.

This study aimed to evaluate the predictive value of procalcitonin (PCT) in ventilator-associated pneumonia (VAP) after cardiac valve replacement. A total of 80 patients who underwent cardiac valve replacement in our department were enrolled in this study. Of these patients,40 were diagnosed with VAP and assigned to the observation group, while the other 40 patients not diagnosed with VAP were assigned to the control group. The changes in serum PCT, white blood cell count and C-reactive protein (CRP) were observed before each operation (T0), on the first day after the operation (T1), the second day after the operation (T2) and the third day after the operation (T3). After the operation, the serum PCT in the observation group was significantly higher than those at different time points after the operation, and also significantly higher than those in the control group (p < .05). In the control group, PCT was significantly higher after the operation than before the operation (p < .05), but the differences among the different postoperative time points were not statistically significant (p > .05). In the two groups, the white blood cell count and CRP were significantly higher after the operation than before the operation (p < .05), but the differences between the two groups were not statistically significant (p > .05). Serum PCT is an early, sensitive and highly specific high-risk monitoring index and has an early prediction value for VAP after cardiac valve replacement.

Using flexible methods to determine risk factors for ventilator-associated pneumonia in the Netherlands.

Seven hospitals participated in the Dutch national surveillance for ventilator-associated pneumonia (VAP) and its risk factors. We analysed time-independent and time-dependent risk factors for VAP using the standard Cox regression and the flexible Weighted Cumulative Effects method (WCE) that evaluates both current and past exposures. The prospective surveillance of intensive care patients aged ≥16 years and ventilated ≥48 hours resulted in the inclusion of 940 primary ventilation periods, comprising 7872 ventilation days. The average VAP incidence density was 10.3/1000 ventilation days. Independent risk factors were age (16-40 years at increased risk: HR 2.42 95% confidence interval 1.07-5.50), COPD (HR 0.19 [0.04-0.78]), current sedation score (higher scores at increased risk), current selective oropharyngeal decontamination (HR 0.19 [0.04-0.91]), jet nebulizer (WCE, decreased risk), intravenous antibiotics for selective decontamination of the digestive tract (ivSDD, WCE, decreased risk), and intravenous antibiotics not for SDD (WCE, decreased risk). The protective effect of ivSDD was afforded for 24 days with a delay of 3 days. For some time-dependent variables, the WCE model was preferable over standard Cox proportional hazard regression. The WCE method can furthermore increase insight into the active time frame and possible delay herein of a time-dependent risk factor.

One functional variant in the 3'-untranslated region of TLR4 is associated with the elevated risk of ventilator-associated pneumonia in the patients with chronic obstructive pulmonary disease.

The aim of this study was to identify the association polymorphism (rs11536889) in the 3'-untranslated region (3'-UTR) of Toll-like receptors 4 (TLR4) and the risk for ventilator-associated pneumonia (VAP). miRNA database online and luciferase assays were used to validate TLR4 as the target gene of miR-1236. Enzyme-linked immunosorbent assay analysis and western blot were used to analyze the level of TLR4 in different genotype groups. In the present study, miR-1236 was predicted to bind to the rs11536889 G allele rather than the rs11536889 C allele, which was further confirmed by the luciferase activity suppressed by a fragment of 3'-UTR containing the rs11536889 G allele induced by lipopolysaccharide (LPS) and interleukin-6 (IL-6). Bronchial epithelial cells isolated from participants genotyped as GG, GC, and CC, with no remarkable difference in TLR4 messenger RNA (mRNA) levels were observed among these genotype groups. After stimulating by LPS, a TLR4 ligand, the CC-genotyped cells expressed higher levels of IL-8, IL-6, and tumor necrosis factor alpha (TNF-α) on their surfaces than cells with the other genotypes. Finally, the western blot analysis results showed that the expression level of IL-8, IL-6, and TNF-α protein was much higher in the CC group than the GC and GG groups subsequent to stimulation by LPS, and the IL-8, IL-6, and TNF-α protein levels in the GC were grouped much lower compared with the GG group. These findings indicated the regulatory association of miR-1236 with TLR4 and the abnormal expression of TLR4 caused by the presence of rs11536889 in the 3'-UTR of mRNA, which interfere with its interaction with the miR-1236, contributing to the risk of VAP.

Antimicrobial polymer modifications to reduce microbial bioburden on endotracheal tubes and ventilator associated pneumonia.

Hospital associated infections (HAIs), infections acquired by patients during care in a hospital, remain a prevalent issue in the healthcare field. These infections often occur with the use of indwelling medical devices, such as endotracheal tubes (ETTs), that can result in ventilator-associated pneumonia (VAP). When examining the various routes of infection, VAP is associated with the highest incidence, rate of morbidity, and economic burden. Although ETTs are essential for the survival of patients requiring mechanical ventilation, their use comes with complications. The presence of an ETT in the airway impairs physiological host defense mechanisms for clearance of pathogens and provides a platform for oropharynx microorganism transport to the sterile tracheobronchial network. Antibiotics are administered to treat lower respiratory infections; however, they are not always effective and consequently can result in increased antibiotic resistance. Prophylactic approaches by altering the surface of ETTs to prevent the establishment and growth of bacteria have exhibited promising results. In addition, passive surface modifications that prevent bacterial establishment and growth, or active coatings that possess a bactericidal effect have also proven effective. In this review we aim to highlight the importance of preventing biofilm establishment on indwelling medical devices, focusing on ETTs. We will investigate successful antimicrobial modifications to ETTs and the future avenues that will ultimately decrease HAIs and improve patient care. STATEMENT OF SIGNIFICANCE: Infections that occur with indwelling medicals devices remain a constant concern in the medical field and can result in hospital-acquired infections. Specifically, ventilator associated pneumonia (VAP) occurs with the use of an endotracheal tube (ETT). Infections often require use of antibiotics and can result in patient mortality. Our review includes a summary of the recent collective work of antimicrobial ETT modifications and potential avenues for further investigations in an effort to reduce VAP associated with ETTs. Polymer modifications with antibacterial nature have been developed and tested; however, a focus on ETTs is lacking and clinical availability of new antimicrobial ETT devices is limited. Our collective work shows the successful and prospective applications to the surfaces of ETTs that can support researchers and physicians to create safer medical devices.

Detecting Early Markers of Ventilator-Associated Pneumonia by Analysis of Exhaled Gas.

OBJECTIVES: The detection of microbial volatile organic compounds or host response markers in the exhaled gas could give an earlier diagnosis of ventilator-associated pneumonia. Gas chromatography-ion mobility spectrometry enables noninvasive, rapid, and sensitive analysis of exhaled gas. Using a rabbit model of ventilator-associated pneumonia we determined if gas chromatography-ion mobility spectrometry is able to detect 1) ventilator-associated pneumonia specific changes and 2) bacterial species-specific changes in the exhaled gas. DESIGN: Experimental in vivo study. SETTING: University research laboratory. SUBJECTS: Female New Zealand White rabbits. INTERVENTIONS: Animals were anesthetized and mechanically ventilated. To induce changes in the composition of exhaled gas we induced ventilator-associated pneumonia via endobronchial instillation of either Escherichia coli group (n = 11) or Pseudomonas aeruginosa group (n = 11) after 2 hours of mechanical ventilation. In a control group (n = 11) we instilled sterile lysogeny broth endobronchially. MEASUREMENTS AND MAIN RESULTS: Gas chromatography-ion mobility spectrometry gas analysis, CT scans of the lungs, and blood samples were obtained at four measurement points during the 10 hours of mechanical ventilation. The volatile organic compound patterns in the exhaled gas were compared and correlated with ventilator-associated pneumonia severity. Sixty-seven peak areas showed changes in signal intensity in the serial gas analyses. The signal intensity changes in 10 peak regions differed between the groups. Five peak areas (P_648_36, indole, P_714_278, P_700_549, and P_727_557) showed statistically significant changes of signal intensity. CONCLUSIONS: This is the first in vivo study that shows the potential of gas chromatography-ion mobility spectrometry for early detection of ventilator-associated pneumonia specific volatile organic compounds and species differentiation by noninvasive analyses of exhaled gas.

Diagnostic efficacy of serum procalcitonin, C-reactive protein concentration and clinical pulmonary infection score in Ventilator-Associated Pneumonia.

OBJECTIVE: The aim of this study was to evaluate the diagnostic efficacy of serum procalcitonin (PCT), c-reactive protein (CRP) concentration and clinical pulmonary infection score(CPIS) in ventilator-associated pneumonia(VAP). METHODS: Forty-nine patients who were admitted to the intensive care unit (ICU) of Zhejiang Hospital with suspected VAP were recruited in this study. The serum level of PCT and CRP of all patients were measured and CPIS was calculated at the time of VAP suspected diagnosis. Of the included 49 patients, 24 were finally confirmed of VAP by microbiology assay. And the other 25 patients were considered as clinical suspected VAP without microbiology confirmation. The diagnostic sensitivity, specificity and area under the receiver operating characteristic (ROC) curve (AUC) were calculated using the serum PCT, CRP concentration and CPIS. The correlation among serum PCT, CRP concentration and CPIS were also evaluated by Spearson correlation test. RESULTS: A total of 100 bronchoscopic aspiration sputum specimen were examined in bacterial culture. 30 samples were found with suspected pathogenic bacteria. Six samples were found with 2 types of suspected pathogenic bacteria. PCT serum concentration and CPIS score were significantly different (P<0.05) between the patient group [1.4 (0.68 ∼ 2.24), 6.0 (4.25 ∼ 8.00)] and the control group [0.4 (0.17 ∼ 1.39), 3.0 (1.00 ∼ 5.00)] ; However, the serum CRP [102.8(66.75 ∼ 130.90) vs 86.1(66.95 ∼ 110.10)] was not statistically different between the two groups (P>0.05). A significant correlation was found between serum PCT and CRP concentrations (r=0.55, P<0.01), but not between PCT vs CPIS and CRP vs CPIS (p>0.05). The diagnostic sensitivity, specificity and AUC were 72.0%, 75.0%, 0.81 (0.69 ∼ 0.93) for CPIS; 60.0%, 87.5%, 0.76 (0.62 ∼ 0.90) for PCT and 68.0%, 58.3%, 0.59 (0.43 ∼ 0.76) for CRP. CONCLUSION: PCT serum level and CPIS score are elevated in VAP patients and could therefore represent potential biomarkers for VAP early diagnosis.

Airway Devices in Ventilator-Associated Pneumonia Pathogenesis and Prevention.

Airway devices play a major role in the pathogenesis of microaspiration of contaminated oropharyngeal and gastric secretions, tracheobronchial colonization, and ventilator-associated pneumonia (VAP) occurrence. Subglottic secretion drainage is an effective measure for VAP prevention, and no routine change of ventilator circuit. Continuous control of cuff pressure, silver-coated tracheal tubes, low-volume low-pressure tracheal tubes, and the mucus shaver are promising devices that should be further evaluated by large randomized controlled trials. Polyurethane-cuffed, conical-shaped cuff, and closed tracheal suctioning system are not effective and should not be used for VAP prevention.

How Can We Distinguish Ventilator-Associated Tracheobronchitis from Pneumonia?

Ventilator-associated tracheobronchitis (VAT) might represent an intermediate process between lower respiratory tract colonization and ventilator-associated pneumonia (VAP), or even a less severe spectrum of VAP. There is an urgent need for new concepts in the arena of ventilator-associated lower respiratory tract infections. Ideally, the gold standard of care is based on prevention rather than treatment of respiratory infection. However, despite numerous and sometimes imaginative efforts to validate the benefit of these measures, most clinicians now accept that currently available measures have failed to eradicate VAP. Stopping the progression from VAT to VAP could improve patient outcomes.

Management of Ventilator-Associated Pneumonia: Guidelines.

Two recent major guidelines on diagnosis and treatment of ventilator-associated pneumonia (VAP) recommend consideration of local antibiotic resistance patterns and individual patient risks for resistant pathogens when formulating an initial empiric antibiotic regimen. One recommends against invasive diagnostic techniques with quantitative cultures to determine the cause of VAP; the other recommends either invasive or noninvasive techniques. Both guidelines recommend short-course therapy be used for most patients with VAP. Although neither guideline recommends use of procalcitonin as an adjunct to clinical judgment when diagnosing VAP, they differ with respect to use of serial procalcitonin to shorten the length of antibiotic treatment.

Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia.

Murine infection models are critical for understanding disease pathogenesis and testing the efficacy of novel therapeutics designed to combat causative pathogens. Infectious pneumonia is among the most common infections presented by patients in the clinic and thus warrants an appropriate in vivo model. Typical pneumonia models use intranasal inoculation, which deposits excessive organisms outside the lung, causing off-target complications and symptoms, such as sinusitis, gastritis, enteritis, physical trauma, or microparticle misting to mimic aerosol spread more typical of viral, tuberculous, or fungal pneumonia. These models do not accurately reflect the pathogenesis of typical community- or healthcare-acquired bacterial pneumonia. In contrast, this murine model of oropharyngeal aspiration pneumonia mimics the droplet route in healthcare-acquired pneumonia. Inoculating 50 µL of the bacteria suspension into the oropharynx of anesthetized mice causes reflexive aspiration, which results in pneumonia. With this model, one can examine the pathogenesis of pneumonia-causing pathogens and new treatments to combat these diseases.

Incidences of Pseudomonas aeruginosa-Associated Ventilator-Associated Pneumonia within Studies of Respiratory Tract Applications of Polymyxin: Testing the Stoutenbeek Concurrency Postulates.

Regimens containing topical polymyxin appear highly effective at preventing ventilator-associated pneumonia (VAP) overall and, more so, VAP caused by Gram-negative bacteria. However, Stoutenbeek's postulates that VAP incidences within studies of topical antibiotics depend on the context of whether the component (control and intervention) groups of each study were concurrent versus nonconcurrent remain untested. The literature was searched for concurrent control (CC) versus nonconcurrent control (NCC) designed studies of respiratory tract applications of topical polymyxin to mechanically ventilated (MV) patients that reported incidences of Pseudomonas-associated ventilator-associated pneumonia (PsVAP). Studies of various interventions other than topical polymyxin (nonpolymyxin studies) served to provide additional points of reference. The PsVAP incidences within the component groups of all studies were benchmarked against groups from observational studies. This was undertaken by meta-regression using generalized estimating equation methods. Dot plots, caterpillar plots, and funnel plots enable visual benchmarking. The PsVAP benchmark (and 95% confidence interval [CI]) derived from 102 observational groups is 4.6% (4.0 to 5.3%). In contrast, the mean PsVAP within NCC polymyxin intervention groups (1.6%; CI, 1.0 to 4.5%) is lower than that of all other component group categories. The mean PsVAP within CC polymyxin control groups (9.9%; CI, 7.6 to 12.8%) is higher than that of all other component group categories. The PsVAP incidences of control and intervention groups of studies of respiratory tract applications of polymyxin are dependent on whether the groups were within a concurrent versus nonconcurrent study. Stoutenbeek's concurrency postulates are validated.

Antibiotics De-Escalation in the Treatment of Ventilator-Associated Pneumonia in Trauma Patients: A Retrospective Study on Propensity Score Matching Method.

BACKGROUND: Antimicrobial de-escalation refers to starting the antimicrobial treatment with broad-spectrum antibiotics, followed by narrowing the drug spectrum according to culture results. The present study evaluated the effect of de-escalation on ventilator-associated pneumonia (VAP) in trauma patients. METHODS: This retrospective study was conducted on trauma patients with VAP, who received de-escalation therapy (de-escalation group) or non-de-escalation therapy (non-de-escalation group). Propensity score matching method was used to balance the baseline characteristics between both groups. The 28-day mortality, length of hospitalization and Intensive Care Unit stay, and expense of antibiotics and hospitalization between both groups were compared. Multivariable analysis explored the factors that influenced the 28-day mortality and implementation of de-escalation. RESULTS: Among the 156 patients, 62 patients received de-escalation therapy and 94 patients received non-de-escalation therapy. No significant difference was observed in 28-day mortality between both groups (28.6% vs. 23.8%, P = 0.620). The duration of antibiotics treatment in the de-escalation group was shorter than that in the non-de-escalation group (11 [8-13] vs. 14 [8-19] days, P = 0.045). The expenses of antibiotics and hospitalization in de-escalation group were significantly lower than that in the non-de-escalation group (6430 ± 2730 vs. 7618 ± 2568 RMB Yuan, P = 0.043 and 19,173 ± 16,861 vs. 24,184 ± 12,039 RMB Yuan, P = 0.024, respectively). Multivariate analysis showed that high Acute Physiology and Chronic Health Evaluation II (APACHE II) score, high injury severity score, multi-drug resistant (MDR) infection, and inappropriate initial antibiotics were associated with patients' 28-day mortality, while high APACHE II score, MDR infection and inappropriate initial antibiotics were independent factors that prevented the implementation of de-escalation. CONCLUSIONS: De-escalation strategy in the treatment of trauma patients with VAP could reduce the duration of antibiotics treatments and expense of hospitalization, without increasing the 28-day mortality and MDR infection.

The rapid in vivo evolution of Pseudomonas aeruginosa in ventilator-associated pneumonia patients leads to attenuated virulence.

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe airway infections in humans. These infections are usually difficult to treat and associated with high mortality rates. While colonizing the human airways, P. aeruginosa could accumulate genetic mutations that often lead to its better adaptability to the host environment. Understanding these evolutionary traits may provide important clues for the development of effective therapies to treat P. aeruginosa infections. In this study, 25 P. aeruginosa isolates were longitudinally sampled from the airways of four ventilator-associated pneumonia (VAP) patients. Pacbio and Illumina sequencing were used to analyse the in vivo evolutionary trajectories of these isolates. Our analysis showed that positive selection dominantly shaped P. aeruginosa genomes during VAP infections and led to three convergent evolution events, including loss-of-function mutations of lasR and mpl, and a pyoverdine-deficient phenotype. Specifically, lasR encodes one of the major transcriptional regulators in quorum sensing, whereas mpl encodes an enzyme responsible for recycling cell wall peptidoglycan. We also found that P. aeruginosa isolated at late stages of VAP infections produce less elastase and are less virulent in vivo than their earlier isolated counterparts, suggesting the short-term in vivo evolution of P. aeruginosa leads to attenuated virulence.

Co-infection of Pseudomonas aeruginosa and Stenotrophomonas maltophilia in hospitalised pneumonia patients has a synergic and significant impact on clinical outcomes.

Ventilator-acquired pneumonia and hospital community-acquired pneumonia are frequently caused by Gram-negative and -positive bacteria. We noted that pneumonia patients with co-infection of Pseudomonas aeruginosa and Stenotrophomonas maltophilia had a poor clinical outcome. To verify this, we retrospectively reviewed pneumonia cases at Hebei General Hospital from 2010 to 2015. These cases were grouped into four categories: (1) co-infection with P. aeruginosa and S. maltophilia, (2) infection with P. aeruginosa, (3) infection with S. maltophilia and (4) infection with none of the known pneumonia-causing pathogens. The numbers of cases in each group were 50, 40, 41 and 33, with mortality rates of 64.0%, 12.5%, 14.6% and 6.1%, respectively. The analysed results indicated that a co-infection of P. aeruginosa and S. maltophilia had a synergic impact on the mortality of pneumonia patients. Therefore, future research is needed to develop treatment strategies for the co-infected patients to reduce the rate of mortality.

A Comparison of Clinical Characteristics and Outcomes of Ventilator-Associated Pneumonias Among Burn Patients by Diagnostic Criteria Set.

OBJECTIVES: The National Healthcare Safety Network (NHSN) replaced its old definition for ventilator-associated pneumonia (VAP) with ventilator-associated events (VAEs) in 2013. Little data is available comparing the two definitions in burn patients. METHODS: Data from 2011 to 2014 were collected on burn patients mechanically ventilated for at least 2 days. VAP was determined using two methods: (1) pneumonia as defined by the previous more clinical CDC (NHSN) definition captured in the burn registry; (2) pneumonia as defined by the recent CDC (NHSN) standard of VAEs where patients meeting the criteria for possible VAP were considered having a pneumonia. Cohen kappa statistic was measured to compare both definitions, and chi-square and ANOVA to compare admission and clinical outcomes. RESULTS: There were 266 burn patients who were mechanically ventilated for at least 2 days between 2011 and 2014. One hundred patients (37.5%) met the criteria by the old definition and 35 (13.1%) met the criteria for both. The kappa statistic was 0.34 (95% confidence interval 0.23-0.45), suggesting weak agreement. Those who met both definitions were mechanically ventilated for a longer period of time (P = 0.0003), and had a longer intensive care unit (ICU) length of stay (LOS) (P = 0.0004) and hospital LOS (P = 0.0014). CONCLUSIONS: There is weak agreement between the two definitions of VAP in severely burn patients. However, patients who met both VAP definitions had longer ventilator days, ICU, and hospital stays.

Pathogenic Link Between Postextubation Pneumonia and Ventilator-Associated Pneumonia: An Experimental Study.

BACKGROUND: The presence of an endotracheal tube is the main cause for developing ventilator-associated pneumonia (VAP), but pneumonia can still develop in hospitalized patients after endotracheal tube removal (postextubation pneumonia [PEP]). We hypothesized that short-term intubation (24 hours) can play a role in the pathogenesis of PEP. To test such hypothesis, we initially evaluated the occurrence of lung colonization and VAP in sheep that were intubated and mechanically ventilated for 24 hours. Subsequently, we assessed the incidence of lung colonization and PEP at 48 hours after extubation in sheep previously ventilated for 24 hours. METHODS: To simulate intubated intensive care unit patients placed in semirecumbent position, 14 sheep were intubated and mechanically ventilated with the head elevated 30° above horizontal. Seven of them were euthanized after 24 hours (Control Group), whereas the remaining were euthanized after being awaken, extubated, and left spontaneously breathing for 48 hours after extubation (Awake Group). Criteria of clinical diagnosis of pneumonia were tested. Microbiological evaluation was performed on autopsy in all sheep. RESULTS: Only 1 sheep in the Control Group met the criteria of VAP after 24 hours of mechanical ventilation. However, heavy pathogenic bacteria colonization of trachea, bronchi, and lungs (range, 10-10 colony-forming unit [CFU]/g) was reported in 4 of 7 sheep (57%). In the Awake Group, 1 sheep was diagnosed with VAP and 3 developed PEP within 48 hours after extubation (42%), with 1 euthanized at 30 hours because of respiratory failure. On autopsy, 5 sheep (71%) confirmed pathogenic bacterial growth in the lower respiratory tract (range, 10-10 CFU/g). CONCLUSIONS: Twenty-four hours of intubation and mechanical ventilation in semirecumbent position leads to significant pathogenic colonization of the lower airways, which can promote the development of PEP. Strategies directed to prevent pathogenic microbiological colonization before and after mechanical ventilation should be considered to avert the onset of PEP.