Outcomes associated with ventilator-associated events (VAE), respiratory infections (VARI), pneumonia (VAP) and tracheobronchitis (VAT) in ventilated pediatric ICU patients: A multicentre prospective cohort study

OBJECTIVES

An objective categorization of respiratory infections based on outcomes is an unmet clinical need. Ventilator-associated pneumonia and tracheobronchitis remain used in clinical practice, whereas ventilator-associated events (VAE) are limited to surveillance purposes.

RESEARCH METHODOLOGY/DESIGN

This was a secondary analysis from a multicentre observational prospective cohort study. VAE were defined as a sustained increase in minimum Oxygen inspired fraction (FiO2) and/or Positive end-expiratory pressures (PEEP) of ≥ 0.2/2 cm H2O respectively, or an increase of 0.15 FiO2 + 1 cm H20 positive end-expiratory pressures for ≥ 1 calendar-day.

SETTING

15 Paediatric Intensive Care Units.

MAIN OUTCOME MEASURES

Mechanical ventilation duration, intensive care and hospital length of stay; (LOS) and mortality.

RESULTS

A cohort of 391 ventilated children with an age (median, [Interquartile Ranges]) of 1 year[0.2-5.3] and 7 days[5-10] of mechanical ventilation were included. Intensive care and hospital stays were 11 [7-19] and 21 [14-39] days, respectively. Mortality was 5.9 %. Fifty-eight ventilator-associated respiratory infections were documented among 57 patients: Seventeen (29.3 %) qualified as ventilator-associated pneumonia (VAP) and 41 (70.7 %) as ventilator-associated tracheobronchitis (VAT). Eight pneumonias and 16 tracheobronchitis (47 % vs 39 %,P = 0.571) required positive end-expiratory pressure or oxygen increases consistent with ventilator-associated criteria. Pneumonias did not significantly impact on outcomes when compared to tracheobronchitis. In contrast, infections (pneumonia or tracheobronchitis) following VAEs criteria were associated with > 6, 8 and 15 extra-days of ventilation (16 vs 9.5, P = 0.001), intensive care stay (23.5 vs 15; P = 0.004) and hospital stay (39 vs 24; P = 0.015), respectively.

CONCLUSION

When assessing ventilated children with respiratory infections, VAE apparently is associated with higher ventilator-dependency and LOS compared with pneumonia or tracheobronchitis.

IMPLICATIONS FOR PRACTICE

Incorporating the modification of ventilatory settings for further categorization of the respiratory infections may facilitate therapeutic management among ventilated patients.

Relationship between SARS-CoV-2 infection and the incidence of ventilator-associated lower respiratory tract infections: a European multicenter cohort study

PURPOSE

Although patients with SARS-CoV-2 infection have several risk factors for ventilator-associated lower respiratory tract infections (VA-LRTI), the reported incidence of hospital-acquired infections is low. We aimed to determine the relationship between SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, and the incidence of VA-LRTI.

METHODS

Multicenter retrospective European cohort performed in 36 ICUs. All adult patients receiving invasive mechanical ventilation > 48 h were eligible if they had: SARS-CoV-2 pneumonia, influenza pneumonia, or no viral infection at ICU admission. VA-LRTI, including ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP), were diagnosed using clinical, radiological and quantitative microbiological criteria. All VA-LRTI were prospectively identified, and chest-X rays were analyzed by at least two physicians. Cumulative incidence of first episodes of VA-LRTI was estimated using the Kalbfleisch and Prentice method, and compared using Fine-and Gray models.

RESULTS

1576 patients were included (568 in SARS-CoV-2, 482 in influenza, and 526 in no viral infection groups). VA-LRTI incidence was significantly higher in SARS-CoV-2 patients (287, 50.5%), as compared to influenza patients (146, 30.3%, adjusted sub hazard ratio (sHR) 1.60 (95% confidence interval (CI) 1.26 to 2.04)) or patients with no viral infection (133, 25.3%, adjusted sHR 1.7 (95% CI 1.2 to 2.39)). Gram-negative bacilli were responsible for a large proportion (82% to 89.7%) of VA-LRTI, mainly Pseudomonas aeruginosa, Enterobacter spp., and Klebsiella spp.

CONCLUSIONS

The incidence of VA-LRTI is significantly higher in patients with SARS-CoV-2 infection, as compared to patients with influenza pneumonia, or no viral infection after statistical adjustment, but residual confounding may still play a role in the effect estimates.

The importance of airway and lung microbiome in the critically ill

During critical illness, there are a multitude of forces such as antibiotic use, mechanical ventilation, diet changes and inflammatory responses that could bring the microbiome out of balance. This so-called dysbiosis of the microbiome seems to be involved in immunological responses and may influence outcomes even in individuals who are not as vulnerable as a critically ill ICU population. It is therefore probable that dysbiosis of the microbiome is a consequence of critical illness and may, subsequently, shape an inadequate response to these circumstances.Bronchoscopic studies have revealed that the carina represents the densest site of bacterial DNA along healthy airways, with a tapering density with further bifurcations. This likely reflects the influence of micro-aspiration as the primary route of microbial immigration in healthy adults. Though bacterial DNA density grows extremely sparse at smaller airways, bacterial signal is still consistently detectable in bronchoalveolar lavage fluid, likely reflecting the fact that lavage via a wedged bronchoscope samples an enormous surface area of small airways and alveoli. The dogma of lung sterility also violated numerous observations that long predated culture-independent microbiology.The body's resident microbial consortia (gut and/or respiratory microbiota) affect normal host inflammatory and immune response mechanisms. Disruptions in these host-pathogen interactions have been associated with infection and altered innate immunity.In this narrative review, we will focus on the rationale and current evidence for a pathogenic role of the lung microbiome in the exacerbation of complications of critical illness, such as acute respiratory distress syndrome and ventilator-associated pneumonia.

Accuracy of ventilator-associated events for the diagnosis of ventilator-associated lower respiratory tract infections

Background

The aim of this study was to investigate the concordance between ventilator-associated events (VAE) and ventilator-associated lower respiratory tract infections (VA-LRTI), and their impact on outcome.

Methods

This retrospective study was performed in five 10-bed ICUs of a teaching hospital, during a 2-year period. Ventilator-associated lower respiratory tract infections (VA-LRTI), including ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP) were prospectively diagnosed. The agreement between VAE, VAT and VAP was assessed by k statistics.

Results

A total of 1059 patients (15,029 ventilator-days) were included. 268 VAP (17.8 per 1000 ventilator-days), 127 VAT (8.5 per 1000 ventilator-days) and 262 VAE (17.4 per 1000 ventilator-days) were diagnosed. There was no agreement between VAT and VAE, and the agreement was poor between VAP and VAE (k = 0.12, 95% CI 0.03–0.20). VAE and VA-LRTI were associated with significantly longer duration of mechanical ventilation, ICU and hospital length of stay. VAP, VAT and VAE were not significantly associated with mortality in multivariate analysis.

Conclusions

The agreement was poor between VAE and VAP. No agreement was found between VAE and VAT. VAE episodes were significantly associated with longer duration of mechanical ventilation and length of stay, but not with ICU mortality.

Host-pathogen interaction during mechanical ventilation: systemic or compartmentalized response?

Patients admitted to the intensive care unit (ICU) often require invasive mechanical ventilation. Ventilator-associated lower respiratory tract infections (VA-LRTI), either ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP), are the most common complication among this patient cohort. VAT and VAP are currently diagnosed and treated as separate entities, viewed as binary disease elements despite an inherent subjectivity in distinguishing them clinically. This paper describes a new approach to pulmonary infections in critically ill patients. Our conjecture is that the host-pathogen interaction during mechanical ventilation determines a local compartmentalized or systemic de-compartmentalized response, based on host immunity and inflammation, and the pathogenic potential of the infecting organism. This compartmentalized or de-compartmentalized response establishes disease severity along a continuum of colonization, VAT or VAP. This change in approach is underpinned by the dissemination hypothesis, which acknowledges the role of immune and inflammatory systems in determining host response to pathogenic organisms in the lower respiratory tract. Those with intact immune and inflammatory pathways may limit infection to a compartmentalized VAT, while immunosuppressed mechanically ventilated patients are at greater risk of a de-compartmentalized VAP. Taking this model from the realm of theory to the bedside will require a greater understanding of inflammatory and immune pathways, and the development of novel disease-specific biomarkers and diagnostic techniques. Advances will lead to early initiation of optimal bespoke antimicrobial therapy, where the intensity and duration of therapy are tailored to clinical, immune and biomarker response. This approach will benefit towards a personalized treatment.

Acinetobacter etiology respiratory tract infections associated with mechanical ventilation: what impacts on the prognosis? A retrospective cohort study

INTRODUCTION

Acinetobacter species treatment often represents a challenge. The main objective of this study is identify predictors of ICU mortality in patients submitted to mechanical ventilation (MV).

MATERIALS AND METHODS

Retrospective cohort study. Patients with MV > 48 h who developed a respiratory tract positive culture for Acinetobacter were included, and distinguished among colonized, ventilator-associated pneumonia (VAP) or ventilator-associated tracheobronchitis (VAT) patients. Primary outcome was ICU mortality.

RESULTS

153 patients were in MV and presented positive culture for Acinetobacter calcoaceticus-baumanii complex, 70 of them with VAP, 59 with VAT and 24 patients were colonized. The factors related to ICU mortality were VAP (OR 2.2, 95% CI 1.1-4.5) and shock at the time of diagnosis (OR 4.8, 95% CI 1.8-2.3). In multivariate analysis, only SOFA score at the time of diagnosis (OR 1.06, 95% CI 1.03-1.09) was related with ICU mortality. A paired-matched analysis was performed to assess effect of dual therapy on outcomes, and no effect was found in terms of clinical cure, ICU or hospital mortality or duration of antimicrobial therapy.

CONCLUSIONS

Previous comorbidities and degree of associated organic injury seem to be more important factors in the prognosis than double antibiotic therapy in patients with Acinetobacter-related respiratory infection.

Assessing predictive accuracy for outcomes of ventilator-associated events in an international cohort: the EUVAE study

Purpose

To analyze the impact on patient outcome of ventilator-associated events (VAEs) as defined by the Centers for Disease Control and Prevention (CDC) in 2008, 2013, and the correlation with ventilator-associated pneumonia (VAP) or tracheobronchitis (VAT).

Methods

This was a prospective, observational, multicenter, international study conducted at 13 intensive care units (ICUs); thirty consecutive adults mechanically ventilated for ≥ 48 h per site were eligible, with daily follow-up being recorded in a collaborative web database; VAEs were assessed using the 2013 CDC classification and its 2015 update.

Results

A total of 2856 ventilator days in 244 patients were analyzed, identifying 33 VAP and 51 VAT episodes; 30-day ICU mortality was significantly higher (42.8 vs. 19.6%, p < 0.007) in patients with VAP than in those with VAT. According to the 2013 CDC definitions, 117 VAEs were identified: 113 (96%) were infection-related ventilator-associated complication-plus (IVAC-plus), while possible ventilator-associated pneumonia (PVAP) was found in 64 (56.6%) of them. VAE increased the number of ventilator days and prolonged ICU and hospital LOS (by 5, 11, and 12 days, respectively), with a trend towards increased 30-day mortality (43 vs 28%, p = 0.06). Most episodes (26, 55%) classified as IVAC-plus without PVAP criteria were due to atelectasis. PVAP significantly increased (p < 0.05) ventilator days as well as ICU and hospital LOS (by 10.5, 14, and 13 days, respectively). Only 24 (72.7%) of VAP and 15 (29.4%) of VAT episodes met IVAC-plus criteria.

Conclusions

Respiratory infections (mainly VAT) were the most common complication. VAE algorithms only identified events with surrogates of severe oxygenation deterioration. As a consequence, IVAC definitions missed one fourth of the episodes of VAP and three fourths of the episodes of VAT. Identifying VAT (often missed by IVAC-plus criteria) is important, as VAP and VAT have different impacts on mortality.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5269-7) contains supplementary material, which is available to authorized users.

Inhaled Antibiotics for Ventilator-Associated Infections

Multidrug-resistant organisms are creating a challenge for physicians treating the critically ill. As new antibiotics lag behind the emergence of worsening resistance, intensivists in countries with high rates of extensively drug-resistant bacteria are turning to inhaled antibiotics as adjunctive therapy. These drugs can provide high concentrations of drug in the lung that could not be achieved with intravenous antibiotics without significant systemic toxicity. This article summarizes current evidence describing the use of inhaled antibiotics for the treatment of bacterial ventilator-associated pneumonia and ventilator-associated tracheobronchitis. Preliminary data suggest aerosolized antimicrobials may effectively treat resistant pathogens with high minimum inhibitory concentrations.

A case-control study on the clinical impact of ventilator associated tracheobronchitis in adult patients who did not develop ventilator associated pneumonia

OBJECTIVES

The main objective was to determine whether ventilator-associated tracheobronchitis (VAT) is related to increased length of ICU stay. Secondary endpoints included prolongation of hospital stay, as well as, ICU and hospital mortality.

DESIGN

A retrospective matched case-control study. Each case was matched with a control for duration of ventilation (± 2 days until development of ventilator-associated tracheobronchitis), disease severity (Acute Physiology and Chronic Health Evaluation II) at admission ± 3, diagnostic category and age ±10 years.

PATIENTS

Critically ill adults admitted to a polyvalent 30-beds ICU with the diagnosis of VAT in the period 2013-2016.

MAIN RESULTS

We identified 76 cases of VAT admitted to our ICU during the study period. No adequate controls were found for 3 patients with VAT. There were no significant differences in demographic characteristics, reasons for admission and comorbidities. Patients with VAT had a longer ICU length of stay, median 22 days (14-35), compared to controls, median 15 days (8-27), p=.02. Ventilator days were also significantly increased in VAT patients, median 18 (9-28) versus 9 days (5-16), p=.03. There was no significant difference in total hospital length of stay 40 (28-61) vs. 35days (23-54), p=.32; ICU mortality (20.5 vs. 31.5% p=.13) and hospital mortality (30.1 vs. 43.8% p=.09). We performed a subanalysis of patients with microbiologically proven VAT receiving adequate antimicrobial treatment and did not observe significant differences between cases and the corresponding controls.

CONCLUSIONS

VAT is associated with increased length of intensive care unit stay and longer duration of mechanical ventilation. This effect disappears when patients receive appropriate empirical treatment.

Ventilator-associated respiratory infection in a resource-restricted setting: impact and etiology

Background

Ventilator-associated respiratory infection (VARI) is a significant problem in resource-restricted intensive care units (ICUs), but differences in casemix and etiology means VARI in resource-restricted ICUs may be different from that found in resource-rich units. Data from these settings are vital to plan preventative interventions and assess their cost-effectiveness, but few are available.

Methods

We conducted a prospective observational study in four Vietnamese ICUs to assess the incidence and impact of VARI. Patients ≥ 16 years old and expected to be mechanically ventilated > 48 h were enrolled in the study and followed daily for 28 days following ICU admission.

Results

Four hundred fifty eligible patients were enrolled over 24 months, and after exclusions, 374 patients’ data were analyzed. A total of 92/374 cases of VARI (21.7/1000 ventilator days) were diagnosed; 37 (9.9%) of these met ventilator-associated pneumonia (VAP) criteria (8.7/1000 ventilator days). Patients with any VARI, VAP, or VARI without VAP experienced increased hospital and ICU stay, ICU cost, and antibiotic use (p < 0.01 for all). This was also true for all VARI (p < 0.01 for all) with/without tetanus. There was no increased risk of in-hospital death in patients with VARI compared to those without (VAP HR 1.58, 95% CI 0.75–3.33, p = 0.23; VARI without VAP HR 0.40, 95% CI 0.14–1.17, p = 0.09). In patients with positive endotracheal aspirate cultures, most VARI was caused by Gram-negative organisms; the most frequent were Acinetobacter baumannii (32/73, 43.8%) Klebsiella pneumoniae (26/73, 35.6%), and Pseudomonas aeruginosa (24/73, 32.9%). 40/68 (58.8%) patients with positive cultures for these had carbapenem-resistant isolates. Patients with carbapenem-resistant VARI had significantly greater ICU costs than patients with carbapenem-susceptible isolates (6053 USD (IQR 3806–7824) vs 3131 USD (IQR 2108–7551), p = 0.04) and after correction for adequacy of initial antibiotics and APACHE II score, showed a trend towards increased risk of in-hospital death (HR 2.82, 95% CI 0.75–6.75, p = 0.15).

Conclusions

VARI in a resource-restricted setting has limited impact on mortality, but shows significant association with increased patient costs, length of stay, and antibiotic use, particularly when caused by carbapenem-resistant bacteria. Evidence-based interventions to reduce VARI in these settings are urgently needed.

Electronic supplementary material

The online version of this article (10.1186/s40560-017-0266-4) contains supplementary material, which is available to authorized users.

Use of nebulized antimicrobials for the treatment of respiratory infections in invasively mechanically ventilated adults: a position paper from the European Society of Clinical Microbiology and Infectious Diseases

With an established role in cystic fibrosis and bronchiectasis, nebulized antibiotics are increasingly being used to treat respiratory infections in critically ill invasively mechanically ventilated adult patients. Although there is limited evidence describing their efficacy and safety, in an era when there is a need for new strategies to enhance antibiotic effectiveness because of a shortage of new agents and increases in antibiotic resistance, the potential of nebulization of antibiotics to optimize therapy is considered of high interest, particularly in patients infected with multidrug-resistant pathogens. This Position Paper of the European Society of Clinical Microbiology and Infectious Diseases provides recommendations based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology regarding the use of nebulized antibiotics in invasively mechanically ventilated adults, based on a systematic review and meta-analysis of the existing literature (last search July 2016). Overall, the panel recommends avoiding the use of nebulized antibiotics in clinical practice, due to a weak level of evidence of their efficacy and the high potential for underestimated risks of adverse events (particularly, respiratory complications). Higher-quality evidence is urgently needed to inform clinical practice. Priorities of future research are detailed in the second part of the Position Paper as guidance for researchers in this field. In particular, the panel identified an urgent need for randomized clinical trials of nebulized antibiotic therapy as part of a substitution approach to treatment of pneumonia due to multidrug-resistant pathogens.

Key considerations on nebulization of antimicrobial agents to mechanically ventilated patients

Nebulized antibiotics have an established role in patients with cystic fibrosis or bronchiectasis. Their potential benefit to treat respiratory infections in mechanically ventilated patients is receiving increasing interest. In this consensus statement of the European Society of Clinical Microbiology and Infectious Diseases, the body of evidence of the therapeutic utility of aerosolized antibiotics in mechanically ventilated patients was reviewed and resulted in the following recommendations: Vibrating-mesh nebulizers should be preferred to jet or ultrasonic nebulizers. To decrease turbulence and limit circuit and tracheobronchial deposition, we recommend: (a) the use of specifically designed respiratory circuits avoiding sharp angles and characterized by smooth inner surfaces, (b) the use of specific ventilator settings during nebulization including use of a volume controlled mode using constant inspiratory flow, tidal volume 8 mL/kg, respiratory frequency 12 to 15 bpm, inspiratory:expiratory ratio 50%, inspiratory pause 20% and positive end-expiratory pressure 5 to 10 cm H₂O and (c) the administration of a short-acting sedative agent if coordination between the patient and the ventilator is not obtained, to avoid patient's flow triggering and episodes of peak decelerating inspiratory flow. A filter should be inserted on the expiratory limb to protect the ventilator flow device and changed between each nebulization to avoid expiratory flow obstruction. A heat and moisture exchanger and/or conventional heated humidifier should be stopped during the nebulization period to avoid a massive loss of aerosolized particles through trapping and condensation. If these technical requirements are not followed, there is a high risk of treatment failure and adverse events in mechanically ventilated patients receiving nebulized antibiotics for pneumonia.

Preventing Ventilator-Associated Infections

Mechanical ventilator use is fraught with risk of complications. Ventilator-associated pneumonia (VAP) is a common complication that prolongs stays on the ventilator and increases mortality and costs. The Centers for Disease Control and Prevention recommend the use of the term, ventilator-associated event. Prevention and/or interruption of cycle of inflammation, colonization of respiratory tract, and ventilator-associated tracheobronchitis are key to managing VAP. Modifying risk factors using a ventilator bundle is considered standard of care. The contentious factors and the lack of support for early tracheotomy, parenteral nutrition, and monitoring of gastric residuals are also addressed. Finally, the role of ventilator-associated tracheobronchitis in VAP is discussed.

Implementing a care bundle approach reduces ventilator-associated pneumonia and delays ventilator-associated tracheobronchitis in children: differences according to endotracheal or tracheostomy devices

OBJECTIVE

To reduce ventilator-associated infections (VARI) and improve outcomes for children.

METHODS

This prospective interventional cohort study was conducted in a paediatric intensive care unit (PICU) over three periods: pre-intervention, early post-intervention, and late post-intervention. These children were on mechanical ventilation (MV) for ≥48h.

RESULTS

Overall, 312 children (11.9% of whom underwent tracheostomy) and 6187 ventilator-days were assessed. There was a significant reduction in ventilator-associated pneumonia (VAP) among tracheostomized patients (8.16, 3.27, and 0.65 per 1000 tracheostomy ventilation-days before the intervention, after the general bundle implementation, and after the tracheostomy intervention, respectively). The median time from onset of MV to diagnosis of ventilator-associated tracheobronchitis (VAT) increased from 5.5 to 48 days in the late post-intervention period (p=0.004), and was associated with a significant increase in median 28-day ventilator-free days and PICU-free days. Tracheostomy (odds ratio 7.44) and prolonged MV (odds ratio 2.75) were independent variables significantly associated with VARI. A trend towards a reduction in PICU mortality was observed, from 28.4% to 16.6% (relative risk 0.58).

CONCLUSIONS

The implementation of a care bundle to prevent VARI in children had a different impact on VAP and VAT, diminishing VAP rates and delaying VAT onset, resulting in reduced healthcare resource use. Tracheostomized children were at increased risk of VARI, but preventive measures had a greater impact on them.

From starting mechanical ventilation to ventilator-associated pneumonia, choosing the right moment to start antibiotic treatment

Background

Ventilator-associated pneumonia (VAP) can have a clear onset or may be a result of the gradual appearance of symptoms and signs of VAP (gradual VAP). The aim of this paper is to describe the VAP development process with the intention of discriminating between those pneumonias with a clear beginning and those that are diagnosed after a period of maturation. In addition, we evaluate the effect of the starting time of antibiotic treatment in both situations.

Methods

Consecutive ventilated patients fulfilling VAP criteria were included. The patients were monitored for clinical, microbiological, and inflammatory signs. Patients with VAP were classified into two groups: (1) nongradual VAP (patients in whom all VAP criteria were detected for the first time on the day of diagnosis) and (2) gradual VAP (progressive appearance of signs and symptoms throughout the pre-VAP period [<96 h to >24 h before VAP diagnosis]).

Results

A total of 71 patients with VAP were identified, of whom 43 (61 %) had gradual VAP, most of whom (n = 38, 88 %) had late-onset VAP. Antibiotic treatment was given to 34 (79 %) patients with gradual VAP in the pre-VAP period, and empirical antibiotic treatment was appropriate in 22 patients (51 %). The patients with an appropriate empirical treatment had a higher percentage of early clinical response to treatment (68 % [n = 15] vs. 28 % [n = 7]; p = 0.009). An attempt was made to find a diagnostic test capable of identifying the infectious process underway, but clinical scales and biomarkers of inflammation helped us to achieve acceptable results.

Conclusions

Gradual emergence of VAP, mainly of late onset, is a common condition. Clinicians should be aware of this gradual onset of the infection to establish an early antibiotic treatment, even before the classic diagnostic criteria for VAP are applied.