Developing a new, national approach to surveillance for ventilator-associated events: executive summary

Risk factors and outcomes associated with ventilator associated pneumonia amongst intubated trauma patients admitted to the general intensive care unit of a major trauma centre

Background

Despite the use of care bundles, ventilator associated pneumonia (VAP) remains a frequently occurring health care-associated infection, increasing costs, length of stay (LOS) and mortality. The incidence is higher amongst trauma patients, although due to variable definitions and study populations risk factors for developing VAP are disputed, with few reports from the UK.

Methods

This 6-year review of intubated trauma patients admitted to the general Intensive Care Unit (ICU) of a UK major trauma centre, collected data on suspected risk factors for VAP, as well as demographic information, outcomes and microbiology. Ninety-nine patients who developed VAP within the first 7 days of admission were compared with 191 patient who did not, with multivariable logistic regression used to control for confounding variables.

Results

Univariable analysis suggested that injury severity score (ISS) (34 v 29), head injury (66.7% v 50.8%), polytrauma (79.8% v 68.1%) and ventilator days (10 v 5) were associated with increased risk of VAP, but after adjustment only ventilator days remained significant (OR 1.04, 95% CI 1.01–1.06). Antibiotics within 24 h of admission were associated with reduced odds of developing VAP, whether this was for pulmonary prophylaxis (OR 0.43, 95% CI 0.22–0.83, p = 0.013) or non-pulmonary reasons (OR 0.27, 95% CI 0.15–0.51, p < 0.001).

Conclusions

Only increasing ventilator days was associated with increased odds of developing VAP. The use of early antimicrobials was associated strongly with a reduction in the odds of developing VAP; this could be explained by unmeasured confounding or a prophylactic effect against aspiration.

Airway microbiome dynamics and relationship to ventilator-associated infection in intubated pediatric patients

BACKGROUND

Little is known about the airway microbiome in intubated mechanically ventilated children. We sought to characterize the airway microbiome longitudinally and in association with clinical variables and possible ventilator-associated infection (VAI).

METHODS

Serial tracheal aspirate samples were prospectively obtained from mechanically ventilated subjects under 3 years old from eight pediatric intensive care units in the United States from June 2017 to July 2018. Changes in the tracheal microbiome were analyzed by sequencing bacterial 16S ribosomal RNA gene relative to subject demographics, diagnoses, clinical parameters, outcomes, antibiotic treatment, and the Ventilator-Associated InfectioN (VAIN) score.

RESULTS

A total of 221 samples from 58 patients were processed and 197 samples met the >1000 reads criteria (89%), with an average of 43,000 reads per sample. The median number of samples per subject was 3 (interquartile range [IQR]: 2-5), with a median VAIN score of 2 (IQR: 1-3). Proteobacteria was the highest observed phyla throughout the intubation period, followed by Firmicutes and Actinobacteria. Alpha diversity was negatively associated with days of intubation (p = .032) and VAIN score (p = .016). High VAIN scores were associated with a decrease of Mycobacterium obuense, and an increase of Streptococcus peroris, Porphyromonadaceae family (unclassified species), Veillonella atypica, and several other taxa. No specific pattern of microbiome composition related to clinically diagnosed VAIs was observed.

CONCLUSIONS

Our data demonstrate decreasing alpha diversity with increasing VAIN score and days of intubation. No specific microbiome pattern was associated with clinically diagnosed VAI.

Risk factors and associated outcomes of ventilator-associated events developed in 28 days among sepsis patients admitted to intensive care unit

We hypothesized that Ventilator-Associated Event (VAE) within 28 days upon admission to medical intensive care units (ICUs) can be a predictor for poor outcomes in sepsis patients. We aimed to determine the risk factors and associated outcomes of VAE. A total of 453 consecutive mechanically ventilated (MV) sepsis patients were enrolled. Of them, 136 patients had immune profile study. Early VAE (< 7-day MV, n = 33) was associated with a higher mortality (90 days: 81.8% vs. 23.0% [non-VAE], P < 0.01), while late VAE (developed between 7 and 28 days, n = 85) was associated with longer MV day (43.8 days vs. 23.3 days [non-VAE], P < 0.05). The 90-day Kaplan–Meier survival curves showed three lines that separate the groups (non-VAE, early VAE, and late VAE). Cox regression models with time-varying coefficient covariates (adjusted for the number of days from intubation to VAE development) confirmed that VAE which occurred within 28 days upon admission to the medical ICUs can be associated with higher 90-day mortality. The risk factors for VAE development include impaired immune response (lower human leukocyte antigen D-related expression, higher interleukin-10 expression) and sepsis progression with elevated SOFA score (especially in coagulation sub-score).

High-flow nasal cannula oxygen therapy in idiopathic pulmonary fibrosis patients with respiratory failure

Background

High-flow nasal cannula (HFNC) oxygen therapy is widely applied in idiopathic pulmonary fibrosis (IPF) patients with acute respiratory failure (ARF); however, its advantages over mechanical ventilation (MV) remain unclear. We aimed to compare the clinical outcomes of HFNC oxygen therapy and MV in IPF patients with respiratory failure.

Methods

A retrospective descriptive study of patients with IPF admitted between January 2015 and December 2017 who underwent HFNC oxygen therapy or MV during hospitalization was conducted. The primary outcome was the comparison of in-hospital mortality among HFNC only group, MV with prior HFNC group, and MV only group.

Results

A total of 61 patients with IPF and ARF were included in the current study. Forty-five patients received HFNC oxygen therapy without endotracheal intubation and 16 received MV. The overall hospital mortality rate was 59.0%, of which 53.3% was for HFNC oxygen therapy and 55.6% (5/9) for MV only group (P=1.000). Although no significant difference in the mortality rate was observed among three groups, that of MV with prior HFNC oxygen therapy (n=7) was 100% (P=0.064). Additionally, the HFNC oxygen therapy group showed shorter length of hospital and ICU stay than the MV group (P<0.001).

Conclusions

Patients with IPF and ARF who received MV with prior HFNC oxygen therapy showed increased mortality rate than those who received HFNC only oxygen therapy or MV. Considering the complication rate of MV, need for lung transplantation, and the will to undergo end-of-life care, a proper transition from HFNC oxygen therapy to MV should be planned cautiously.

New guidelines for hospital-acquired pneumonia/ventilator-associated pneumonia: USA vs. Europe

PURPOSE OF REVIEW

The International ERS/ESICM/ESCMID/ALAT guidelines for the management of hospital-acquired pneumonia and ventilator-associated pneumonia were published in 2017 whilst the American guidelines for Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia were launched in 2016 by the Infectious Diseases Society of America/ATS. Both guidelines made updated recommendations based on the most recent evidence sharing not only some parallelisms but also important conceptual differences.

RECENT FINDINGS

Contemporary therapy for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) emphasizes the importance of prompt and appropriate antimicrobial therapy. There is an implicit risk, when appropriate means broad spectrum, that liberal use of antimicrobial combinations will encourage the emergence of multidrug resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant bacteria (PDR) and generate untreatable infections, including carbapenemase resistant infections.

SUMMARY

American and European guidelines have many areas of common agreement such as limiting antibiotic duration. Both guidelines were in favour of a close clinical assessment. Neither recommended a regular use of biomarkers but only in specific circumstances such as dealing with MDR and treatment failure. Risk factor prediction for MDR differed and whilst American guidelines focus on organ failure, the European ones did it in local ecology and septic shock.

Pediatric Ventilator-Associated Events: Analysis of the Pediatric Ventilator-Associated Infection Data

OBJECTIVES

To compare the prevalence of infection applying the proposed pediatric ventilator-associated events criteria versus clinician-diagnosed ventilator-associated infection to subjects in the pediatric ventilator-associated infection study.

DESIGN

Analysis of prospectively collected data from the pediatric ventilator-associated infection study.

SETTING

PICUs of 47 hospitals in the United States, Canada, and Australia.

PATIENTS

Two-hundred twenty-nine children ventilated for greater than 48 hours who had respiratory secretion cultures performed to evaluate for suspected ventilator-associated infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Applying the proposed pediatric ventilator-associated event criteria, 15 of 229 subjects in the ventilator-associated infection study qualified as "ventilator-associated condition" and five of 229 (2%) met criteria for "infection-related ventilator-associated complication." This was compared with 89 of 229 (39%) diagnosed as clinical ventilator-associated infection (Kappa = 0.068). Ten of 15 subjects identified as ventilator-associated condition did not meet criteria for infection-related ventilator-associated complication primarily because they did not receive 4 days of antibiotics. Ventilator-associated condition subjects were similar demographically to nonventilator-associated condition subjects and had similar mortality (13% vs 10%), PICU-free days (6.9 ± 7.7; interquartile range, 0-14 vs 9.8 ± 9.6; interquartile range, 0-19; p = 0.25), but fewer ventilator-free days (6.6 ± 9.3; interquartile range, 1-15 vs 12.4 ± 10.7; interquartile range, 0-22; p = 0.04). The clinical ventilator-associated infection diagnosis in the ventilator-associated infection study was associated with fewer PICU-free days but no difference in mortality or ventilator-free days.

CONCLUSIONS

The ventilator-associated event criteria appear to be insensitive to the clinical diagnosis of ventilator-associated infection. Differentiation between ventilator-associated condition and infection-related ventilator-associated complication was primarily determined by the clinician decision to treat with antibiotics rather than clinical signs and symptoms. The utility of the proposed pediatric ventilator-associated event criteria as a surrogate for ventilator-associated infection criteria is unclear.

Accuracy and Applications of Lung Ultrasound to Diagnose Ventilator-Associated Pneumonia: A Systematic Review

BACKGROUND

Lung ultrasound (LUS) is an accurate tool to diagnose community-acquired pneumonia. However, it is not yet an established tool to diagnose ventilator-associated pneumonia (VAP).

PURPOSE

To assess the evidence about LUS in the diagnosis of VAP, we conducted a systematic review of the literature.

METHODS

We searched PubMed, Embase, Scopus, Web of Science, and LILACS. Two researchers independently selected the studies that met the inclusion criteria. Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to assess the quality of the studies. In a qualitative synthesis, 3 questions guided the review: Q1. What are the sonographic signs of VAP? Q2. How can LUS be combined with others tests or signs of VAP? Q3. What is the role of LUS in VAP screening?

MAIN RESULTS

Three studies (n = 377 patients) with different designs were included. In terms of Q1, the 3 studies assessed the accuracy of sonographic consolidations. In patients suspected for VAP, lobar or hemilobar consolidation alone was not sufficient to diagnose VAP but seems useful to exclude it. The most useful signs were small subpleural consolidations (sensitivity: 81%; specificity: 41%) and dynamic air bronchograms (sensitivity: 44%; specificity: 81%). Two studies were assessed for Q2, when the 2 signs above were included in a clinical score (Ventilator-associated Pneumonia Lung Ultrasound Score associated with quantitative culture of endotracheal aspirate-VPLUS-EAquant), the accuracy was amplified (sensitivity: 48% and specificity: 97% for score ≥4; sensitivity: 78% and specificity: 77% for score ≥3 points). Finally, regarding Q3, no studies have assessed the use of LUS in screening of VAP.

CONCLUSION

Small subpleural consolidations and dynamic air bronchograms were the most useful sonographic signs to diagnose VAP in suspected patients. Clinical scores including LUS had better diagnosis accuracy than LUS alone. There are no data on LUS for VAP screening.

From VAP to VAE: Implications of the New CDC Definitions on a Burn Intensive Care Unit Population

Ventilator-associated pneumonia (VAP) is a frequent complication of severe burn injury. Comparing the current ventilator-associated event-possible VAP definition to the pre-2013 VAP definition, we identified considerably fewer VAP cases in our burn ICU. The new definition does not capture many VAP cases that would have been reported using the pre-2013 definition. Infect Control Hosp Epidemiol 2017;38:867-869.

Empiric antimicrobial therapy for ventilator-associated pneumonia after brain injury

Issues regarding recommendations on empiric antimicrobial therapy for ventilator-associated pneumonia (VAP) have emerged in specific populations.To develop and validate a score to guide empiric therapy in brain-injured patients with VAP, we prospectively followed a cohort of 379 brain-injured patients in five intensive care units. The score was externally validated in an independent cohort of 252 brain-injured patients and its extrapolation was tested in 221 burn patients.The multivariate analysis for predicting resistance (incidence 16.4%) showed two independent factors: preceding antimicrobial therapy ≥48 h (p<0.001) and VAP onset ≥10 days (p<0.001); the area under the receiver operating characteristic curve (AUC) was 0.822 (95% CI 0.770-0.883) in the learning cohort and 0.805 (95% CI 0.732-0.877) in the validation cohort. The score built from the factors selected in multivariate analysis predicted resistance with a sensitivity of 83%, a specificity of 71%, a positive predictive value of 37% and a negative predictive value of 96% in the validation cohort. The AUC of the multivariate analysis was poor in burn patients (0.671, 95% CI 0.596-0.751).Limited-spectrum empirical antimicrobial therapy has low risk of failure in brain-injured patients presenting with VAP before day 10 and when prior antimicrobial therapy lasts <48 h.

Ventilator-associated pneumonia during weaning from mechanical ventilation: role of fluid management

BACKGROUND

Pulmonary edema may alter alveolar bacterial clearance and infectivity. Manipulation of fluid balance aimed at reducing fluid overload may, therefore, influence ventilator-associated pneumonia (VAP) occurrence in intubated patients. The objective of the present study was to assess the impact of a depletive fluid-management strategy on ventilator-associated complication (VAC) and VAP occurrence during weaning from mechanical ventilation.

METHODS

We used data from the B-type Natriuretic Peptide for the Fluid Management of Weaning (BMW) randomized controlled trial performed in nine ICUs across Europe and America. We compared the cumulative incidence of VAC and VAP between the biomarker-driven, depletive fluid-management group and the usual-care group during the 14 days following randomization, using specific competing-risk methods (the Fine and Gray model).

RESULTS

Among the 304 patients analyzed, 41 experienced VAP, including 27 (17.8%) in the usual-care group vs 14 (9.2%) in the interventional group (P = .03). From the Fine and Gray model, the probabilities of VAC and VAP occurrence were both significantly reduced with the interventional strategy while adjusting for weaning outcome as a competing event (subhazard ratios [25th-75th percentiles], 0.44 [0.22-0.87], P = .02 and 0.50 [0.25-0.96], P = .03, respectively).

CONCLUSIONS

Using proper competing risk analyses, we found that a depletive fluid-management strategy, when initiating the weaning process, has the potential for lowering VAP risk in patients who are mechanically ventilated.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00473148; URL: www.clinicaltrials.gov.