The futility of the clinical pulmonary infection score in trauma patients

Polymerase chain reaction for early identification of bacteria causing pneumonia in ventilated surgical and trauma patients

INTRODUCTION

Ventilator-associated pneumonia occurs in 20% to 25% of intubated trauma patients, and early effective antibiotic treatment decreases morbidity and mortality. We sought to determine the sensitivity and specificity of multiplex polymerase chain reaction amplification of bacterial DNA (Biofire FilmArray Pneumonia Panel [BFPP]) obtained during fiberoptic bronchoscopy in predicting the causative bacteria the day of bronchoalveolar lavage (BAL).

METHODS

This diagnostic accuracy study compared results of BAL with quantitative culture and BFPP testing on all intubated trauma and surgery patients suspected of developing pneumonia. Demographics, clinical data, BAL culture results, and BFPP results were recorded. McNemar analysis was performed.

RESULTS

Over a 3-year study period, 151 intubated surgical critical care patients suspected of developing pneumonia underwent 238 BALs with quantitative culture and BFPP testing. Bronchoalveolar lavages that had ≥10 5 colony-forming units/mL growth were considered consistent with the diagnosis of pneumonia. Of the 238 BALs, 82 (34.5%) were considered positive and then correlated to the genomic copy number per milliliter (GCN/mL) reported by BFPP testing.

CONCLUSION

In ventilated patients with high clinical suspicion for pneumonia, a BFPP cutoff value of 10 6 GCN/mL is a sensitive and specific test for initiating antibiotics targeted to the identified organism(s). In addition, a negative BFPP result may limit unnecessary and potentially harmful empiric antibiotic coverage, as its negative predictive value is 99.8%.

LEVEL OF EVIDENCE

Diagnostic Tests/Criteria; Level III.

Antibiogram Surveillance to Determine Appropriate Initial Empiric Antibiotic Therapy for Ventilator-Associated Pneumonia

Background: Our protocolized empiric antibiotic therapy for early (≤7 d) ventilator-associated pneumonia (VAP) and late (>7 d) VAP based on our local antibiogram leads to inappropriate empiric antibiotic therapy (IEAT) approximately 15% of the time. We reviewed our trauma intensive care unit (TICU) antibiogram to determine if sensitivity patterns were changing and warranted protocol adjustments. We hypothesized there would be no change in IEAT over time. Patients and Methods: TICU patients with VAP (bronchoalveolar lavage culture ≥100,000 CFU/mL) between 2017 and 2022 were reviewed. We reviewed the pathogens and sensitivity patterns to identify the IEAT percentage, and we reviewed changes in the rate of antimicrobial days per 1,000 days present for 2018-2022. Results: We noted an increase in IEAT beginning in 2017. In early VAP, the increase in IEAT was because of an increase in identification of gram-negative bacteria isolates (7%-24%), specifically an increase in Pseudomonas (3%-10%) and a decrease in Streptococcus sp. (32%-23%) and Haemophilus influenzae (20%-17%). In late VAP, the increase in IEAT was largely because of an increase in identification of Stenotrophomonas (3%-5%) and Acinetobacter (4%-10%). Antimicrobial use changed as pathogens and sensitivity changed. There were increases in rates per 1,000 days for cefazolin (11.9%), vancomycin (22.8%), cefepime (33.1%), and meropenem (424.7%), whereas there were decreases in rates per 1,000 days for ampicillin/sulbactam (-4.5%) and piperacillin/tazobactam (-9.5%). Conclusions: The change in organisms identified and the increase in IEAT highlight the importance of continuous antibiogram monitoring.

Development and validation of a nomogram for pneumonia risk in burn patients with inhalation injury: a multicenter retrospective cohort study

BACKGROUND

Burn patients with inhalation injury are at higher risk of developing pneumonia, and yet there is no reliable tool for the assessment of the risk for such patients at admission. This study aims to establish a predictive model for pneumonia risk for burn patients with inhalation injury based on clinical findings and laboratory tests.

METHOD

This retrospective study enrolled 546 burn patients with inhalation injury. They were grouped into a training cohort and a validation cohort. The least absolute shrinkage and selection operator (LASSO) regression analysis and binary logistic regression analysis were utilized to identify risk factors for pneumonia. Based on the factors, a nomogram for predicting pneumonia in burn patients with inhalation injury was constructed. Areas under the receiver operating characteristic curves (AUC), calibration plots, and decision curve analysis (DCA) were used to evaluate the efficiency of the nomogram in both the training and validation cohorts.

RESULTS

The training cohort included 432 patients, and the validation cohort included 114 patients, with a total of 225 (41.2%) patients experiencing pneumonia. Inhalation injury, tracheal intubation/tracheostomy, low serum albumin, and high blood glucose were independent risk factors for pneumonia in burn patients with inhalation injury and they were further used to build the nomogram. The AUC of the nomogram in the training and validation cohorts were 0.938 (95% CI: 0.917-0.960) and 0.966 (95% CI: 0.931-1), respectively. The calibration curve for probability of pneumonia showed optimal agreement between the prediction by nomogram and the actual observation, and the DCA indicated that the constructed nomogram conferred high clinical net benefit.

CONCLUSION

This nomogram can accurately predict the risk of developing pneumonia for burn patients with inhalation injury, and help professionals to identify high-risk patients at an early stage as well as to make informed clinical decisions.

Trial of antibiotic restraint in presumed pneumonia: A Surgical Infection Society multicenter pilot

BACKGROUND

Pneumonia is the most common intensive care unit-acquired infection in the trauma and emergency general surgery population. Despite guidelines urging rapid antibiotic use, data supporting immediate antibiotic initiation in cases of suspected infection are limited. Our hypothesis was that a protocol of specimen-initiated antibiotic initiation would have similar compliance and outcomes to an immediate initiation protocol.

METHODS

We devised a pragmatic cluster-randomized crossover pilot trial. Four surgical and trauma intensive care units were randomized to either an immediate initiation or specimen-initiated antibiotic protocol for intubated patients with suspected pneumonia and bronchoscopically obtained cultures who did not require vasopressors. In the immediate initiation arm, antibiotics were started immediately after the culture regardless of patient status. In the specimen-initiated arm, antibiotics were delayed until objective Gram stain or culture results suggested infection. Each site participated in both arms after a washout period and crossover. Outcomes were protocol compliance, all-cause 30-day mortality, and ventilator-free alive days at 30 days. Standard statistical techniques were applied.

RESULTS

A total of 186 patients had 244 total cultures, of which only the first was analyzed. Ninety-three patients (50%) were enrolled in each arm, and 94.6% were trauma patients (84.4% blunt trauma). The median age was 50.5 years, and 21% of the cohort was female. There were no differences in demographics, comorbidities, sequential organ failure assessment, Acute Physiology and Chronic Health Evaluation II, or Injury Severity Scores. Antibiotics were started significantly later in the specimen-initiated arm (0 vs. 9.3 hours; p < 0.0001) with 19.4% avoiding antibiotics completely for that episode. There were no differences in the rate of protocol adherence, 30-day mortality, or ventilator-free alive days at 30 days.

CONCLUSION

In this cluster-randomized crossover trial, we found similar compliance rates between immediate and specimen-initiated antibiotic strategies. Specimen-initiated antibiotic protocol in patients with a suspected hospital-acquired pneumonia did not result in worse clinical outcomes compared with immediate initiation.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level II.

Comparative Evaluation of the Role of Nonbronchoscopic and Bronchoscopic Techniques of Distal Airway Sampling for the Diagnosis of Ventilator-Associated Pneumonia

Background:

The diagnosis of ventilator-associated pneumonia (VAP) remains a challenge, with clinicians mainly relying on clinical, radiological, and bacteriologic strategies to manage patients with VAP.

Aims:

To compare the results of non-bronchoscopic and bronchoscopic techniques of distal airway sampling for the diagnosis of VAP.

Settings and Design:

This was a single-center prospective diagnostic accuracy study done in the 14-bedded intensive care unit of a tertiary care referral hospital.

Materials and Methods:

Patients aged ≥18 years, on mechanical ventilation for ≥48 h, and with clinical suspicion of VAP (fever, leukocytosis, and increased tracheal secretions) either on admission or during their stay were included. Every patient underwent both procedures for sample collection, first non-bronchoscopic protected bronchoalveolar lavage (NP-BAL) and then bronchoscopic BAL (B-BAL). Clinical Pulmonary Infection Score (CPIS) was calculated for each patient and the collected samples were evaluated in laboratory using standard microbiological techniques.

Statistical Analysis Used:

The sensitivity, specificity, positive predictive value, and negative predictive value of NP-BAL and B-BAL for the diagnosis of VAP were calculated taking CPIS score of >6 as index test for the diagnosis of VAP.

Results:

Sixty patients were included in the study. Both NP-BAL and B-BAL had concordance with the CPIS at 69.1%. The concordance between NP-BAL and B-BAL was better at 67.6% with a kappa coefficient of 0.064 (P = −0.593). The yield and sensitivity of NP-BAL were comparable to that of B-BAL.

Conclusions:

The blind NP-BAL is an equally effective method of airway sampling and could be a better alternative to replace more invasive B-BAL for microbiologic diagnosis of VAP.

Incorporating Lung Ultrasound in Clinical Pulmonary Infection Score as an Added Tool for Diagnosing Ventilator-associated Pneumonia: A Prospective Observational Study from a Tertiary Care Center

Background: Clinical pulmonary infection score (CPIS) is an established diagnostic parameter for ventilator-associated pneumonia (VAP). Lung ultrasound (LUS) is an evolving tool for diagnosing VAP. Various scores have been proposed for the diagnosis of VAP, taking LUS as a parameter. We proposed whether replacing LUS with chest radiograph in CPIS criteria will add to the diagnosis of VAP. The current study was done to evaluate the diagnostic accuracy of LUS alone and in combination with clinical and microbiological criteria for VAP by replacing chest radiograph with LUS in CPIS. Materials and methods: We conducted a prospective single-center observational study including 110 patients with suspected VAP to investigate the diagnostic accuracy of LUS. Quantitative mini-bronchoalveolar lavage (mini-BAL) culture was considered the gold standard for diagnosis of VAP. Here, the authors have explored the combination of LUS, clinical, and microbiology parameters for diagnosing VAP. On replacing chest radiograph with LUS, sono-pulmonary infection score (SPIS) and modified SPIS (SPIS-mic, SPIS-cult) was formulated as a substitute for CPIS. Results: Overall LUS performance for VAP diagnosis was good with sensitivity, specificity, positive or negative predictive value, and positive or negative likelihood ratios of 91.3%, 70%, 89%, 75%, 3, and 0.1, respectively. Adding microbiology culture to LUS increased diagnostic accuracy. The areas under the curve for SPIS and modified SPIS were 0.808, 0.815, and 0.913, respectively. Conclusion: The diagnosis of VAP requires agreement between clinical, microbiological, and radiological criteria. Replacing chest radiograph with LUS in CPIS criteria (SPIS) increases diagnostic accuracy for VAP. Adding clinical and culture data to SPIS provided the highest diagnostic accuracy. Clinical parameters along with lung ultrasound increase diagnostic accuracy for VAP. How to cite this article: Samanta S, Patnaik R, Azim A, Gurjar M, Baronia AK, Poddar B, et al. Incorporating Lung Ultrasound in Clinical Pulmonary Infection Score as an Added Tool for Diagnosing Ventilator-associated Pneumonia: A Prospective Observational Study from a Tertiary Care Center. Indian J Crit Care Med 2021;25(3):284-291.

Molecular Profiling of Innate Immune Response Mechanisms in Ventilator-associated Pneumonia

Ventilator-associated pneumonia (VAP) is a common hospital-acquired infection, leading to high morbidity and mortality. Currently, bronchoalveolar lavage (BAL) is used in hospitals for VAP diagnosis and guiding treatment options. Although BAL collection procedures are invasive, alternatives such as endotracheal aspirates (ETA) may be of diagnostic value, however, their use has not been thoroughly explored. Longitudinal ETA and BAL were collected from 16 intubated patients up to 15 days, of which 11 developed VAP. We conducted a comprehensive LC-MS/MS based proteome and metabolome characterization of longitudinal ETA and BAL to detect host and pathogen responses to VAP infection. We discovered a diverse ETA proteome of the upper airways reflective of a rich and dynamic host-microbe interface. Prior to VAP diagnosis by microbial cultures from BAL, patient ETA presented characteristic signatures of reactive oxygen species and neutrophil degranulation, indicative of neutrophil mediated pathogen processing as a key host response to the VAP infection. Along with an increase in amino acids, this is suggestive of extracellular membrane degradation resulting from proteolytic activity of neutrophil proteases. The metaproteome approach successfully allowed simultaneous detection of pathogen peptides in patients' ETA, which may have potential use in diagnosis. Our findings suggest that ETA may facilitate early mechanistic insights into host-pathogen interactions associated with VAP infection and therefore provide its diagnosis and treatment.

Accuracy of the clinical pulmonary infection score to differentiate ventilator-associated tracheobronchitis from ventilator-associated pneumonia

BACKGROUND

Differentiating Ventilator-Associated Tracheobronchitis (VAT) from Ventilator-Associated Pneumonia (VAP) may be challenging for clinicians, yet their management currently differs. In this study, we evaluated the accuracy of the Clinical Pulmonary Infection Score (CPIS) to differentiate VAT and VAP.

METHODS

We performed a retrospective analysis based on the data from 2 independent prospective cohorts. Patients of the TAVeM database with a diagnosis of VAT (n = 320) or VAP (n = 369) were included in the derivation cohort. Patients admitted to the Intensive Care Centre of Lille University Hospital between January 1, 2016 and December 31, 2017 who had a diagnosis of VAT (n = 70) or VAP (n = 139) were included in the validation cohort. The accuracy of the CPIS to differentiate VAT from VAP was assessed within the 2 cohorts by calculating sensitivity and specificity values, establishing the ROC curves and choosing the best threshold according to the Youden index.

RESULTS

The areas under ROC curves of CPIS to differentiate VAT from VAP were calculated at 0.76 (95% CI [0.72-0.79]) in the derivation cohort and 0.67 (95% CI [0.6-0.75]) in the validation cohort. A CPIS value ≥ 7 was associated with the highest Youden index in both cohorts. With this cut-off, sensitivity and specificity were respectively found at 0.51 and 0.88 in the derivation cohort, and at 0.45 and 0.89 in the validation cohort.

CONCLUSIONS

A CPIS value ≥ 7 reproducibly allowed to differentiate VAT from VAP with high specificity and PPV and moderate sensitivity and NPV in our derivation and validation cohorts.

Clinical Diagnosis of Infection in Surgical Intensive Care Unit: You're Not as Good as You Think!

Background: Because of the everincreasing costs and the complexity of institutional medical reimbursement policies, the necessity for extensive laboratory work-up of potentially infected patients has come into question. We hypothesized that intensivists are able to differentiate between infected and non-infected patients clinically, without the need to pan-culture, and are able to identify the location of the infection clinically in order to administer timely and appropriate treatment. Methods: Data collected prospectively on critically ill patients suspected of having an infection in the surgical intensive care unit (SICU) was obtained over a six-month period in a single tertiary academic medical center. Objective evidence of infection derived from laboratory or imaging data was compared with the subjective answers of the three most senior physicians' clinical diagnoses. Results: Thirty-nine critically ill surgical patients received 52 work-ups for suspected infections on the basis of signs and symptoms (e.g., fever, altered mental status). Thirty patients were found to be infected. Clinical diagnosis differentiated infected and non-infected patients with only 61.5% accuracy (sensitivity 60.3%; specificity 64.4%; p = 0.0049). Concordance between physicians was poor (κ = 0.33). Providers were able to predict the infectious source correctly only 60% of the time. Utilization of culture/objective data and SICU antibiotic protocols led to overall 78% appropriate initiation of antibiotics compared with 48% when treatment was based on clinical evaluation alone. Conclusion: Clinical diagnosis of infection is difficult, inaccurate, and unreliable in the absence of culture and sensitivity data. Infection suspected on the basis of signs and symptoms should be confirmed via objective and thorough work-up.

Variations of the lung microbiome and immune response in mechanically ventilated surgical patients

Mechanically ventilated surgical patients have a variety of bacterial flora that are often undetectable by traditional culture methods. The source of infection in many of these patients remains unclear. To address this clinical problem, the microbiome profile and host inflammatory response in bronchoalveolar lavage samples from the surgical intensive care unit were examined relative to clinical pathology diagnoses. The hypothesis was tested that clinical diagnosis of respiratory tract flora were similar to culture positive lavage samples in both microbiome and inflammatory profile. Bronchoalveolar lavage samples were collected in the surgical intensive care unit as standard of care for intubated individuals with a clinical pulmonary infection score of >6 or who were expected to be intubated for >48 hours. Cytokine analysis was conducted with the Bioplex Pro Human Th17 cytokine panel. The microbiome of the samples was sequenced for the 16S rRNA region using the Ion Torrent. Microbiome diversity analysis showed the culture-positive samples had the lowest levels of diversity and culture negative with the highest based upon the Shannon-Wiener index (culture positive: 0.77 ± 0.36, respiratory tract flora: 2.06 ± 0.73, culture negative: 3.97 ± 0.65). Culture-negative samples were not dominated by a single bacterial genera. Lavages classified as respiratory tract flora were more similar to the culture-positive in the microbiome profile. A comparison of cytokine expression between groups showed increased levels of cytokines (IFN-g, IL-17F, IL-1B, IL-31, TNF-a) in culture-positive and respiratory tract flora groups. Culture-positive samples exhibited a more robust immune response and reduced diversity of bacterial genera. Lower cytokine levels in culture-negative samples, despite a greater number of bacterial species, suggest a resident nonpathogenic bacterial community may be indicative of a normal pulmonary environment. Respiratory tract flora samples were most similar to the culture-positive samples and may warrant classification as culture-positive when considering clinical treatment.

Inadequacy of Algorithmic Ventilator-Associated Pneumonia Diagnosis in Acute Care Surgery

Clinical utility of algorithms to diagnose ventilator-associated pneumonia (VAP) in surgical patients has not been established. We aimed to test the diagnostic accuracy of two established methods to reliably diagnose VAP in acutely ill and injured surgical patients. After institutional review board approval, we prospectively collected data on 508 mechanically ventilated acute care surgery patients. Microbiologic samples were taken daily from all patients. Demographics, clinical, laboratory, and radiographic data were collected. The Johanson Criteria (JC) and Clinical Pulmonary Infection Score (CPIS) were calculated and analyzed. Sensitivity, specificity, and positive predictive values (PPV) and negative predictive value (NPV) were calculated in comparison to positive respiratory cultures. Of the 508 patients, 312 (61.4%) were acutely injured; emergent general surgery was performed in 141 (27.8%) patients, and 54 (10.6%) underwent elective operation. Positive respiratory cultures were identified in 198 (39%) of the 508 patients. JC diagnosed VAP in 291 (57.3%) patients (sensitivity 82.8%, specificity 59%, PPV 56.4%, NPV 84.3%, accuracy 68.3%). The CPIS resulted in 189 (37.2%) VAP diagnoses (sensitivity 61.1%, specificity 78.1%, PPV 64%, NPV 75.9%, and accuracy 71.5%). To address the inaccuracy of the algorithms, concordance testing was performed on the data to evaluate correlation between the algorithmic VAP diagnosis criteria and respiratory culture data. Nonconcordance with culture data diagnosis was identified with both JC (rho 0.41) and CPIS (rho 0.41). Sensitivity, specificity, PPV and NPV, and accuracy of both established clinical formulas was unacceptably low in acute care surgery patients.

Diagnostic Efficacy of Serum Amyloid A Protein and Soluble Intercellular Adhesion Molecule 1 in Pediatric Ventilator-Associated Pneumonia

Objectives:

Study of inflammatory biomarkers which may aid in early detection of ventilator-associated pneumonia (VAP) in children and predicting their outcome.

Patients:

Thirty-five children, aged 2 months to 13 years, needed mechanical ventilation (MV) for more than 48 hours due to causes other than pneumonia.

Methods:

Measurement of serum amyloid A (SAA) protein, soluble intercellular adhesion molecule 1 (sICAM-1), and C-reactive protein (CRP), modified clinical pulmonary infection score (CPIS) and performing culture of endotracheal aspirate at the start and on the third day of MV.

Results:

Ventilator-associated pneumonia was diagnosed by CPIS in 6 (17.1%) of 35 patients. On the third day of MV, there was a significant increase in serum mean levels of SAA, sICAM-1, and CRP in comparison to the start of MV ( P = .005, .004, and .01, respectively). Three (50%) of 6 patients with VAP died, while 4 (14.28%) of 28 patients without VAP died. The sensitivity of serum SAA, sICAM-1, and CPIS were 100% for predicting VAP, while specificity was highest for CPIS (96.55%) followed by SAA (93.1%). Combination of CPIS and SAA increased the specificity to 100%. For predicting nonsurvival, serum SAA and sICAM-1 had a sensitivity of 100% and a specificity of 92.86% and 89.29%, respectively.

Conclusion:

Serum amyloid A and sICAM-1 may be considered as reliable markers for detection of VAP. Combination of serum SAA with CPIS increased the specificity to 100%. Measurement of SAA in patients with VAP also had a good predictive value for nonsurvival in such patients.

Influence of intraoperative positive end-expiratory pressure level on pulmonary complications in emergency major trauma surgery

INTRODUCTION

Pulmonary complications have a major impact on the morbidity and mortality of critically ill patients with multiple trauma. Intraoperative protective ventilation with low tidal volume may prevent lung injury and infection, whereas the role of positive end-expiratory pressure (PEEP) levels is unclear. The aim of this study was to evaluate the influence of different intraoperative PEEP levels on incidence of pulmonary complications after emergency trauma surgery.

MATERIAL AND METHODS

We retrospectively analysed data of multiple trauma patients who underwent emergency surgery within 24 h after injury in our level I trauma centre (n = 86). On the basis of their intraoperative PEEP level, patients were divided into a low PEEP group with a PEEP of < 8 mbar and a high PEEP group with a PEEP of 8 mbar or higher.

RESULTS

Besides differences in body mass index and preoperative oxygenation, there were no differences in patients' baseline data. There was a significant difference between incidence of pneumonia within 7 days after trauma surgery, with an incidence 26.7% in the low PEEP group and 7.3% in the high PEEP group (p = 0.02). The low PEEP group had higher pulmonary infection scores at days 3 and 5 after surgery. Oxygenation was better in the higher PEEP group postoperatively. There was no difference with respect to the incidence of acute respiratory distress syndrome, the mortality up until hospital discharge or haemodynamic parameters between groups.

CONCLUSIONS

Higher PEEP levels were associated with perioperative improvement of oxygenation and a lower incidence of pneumonia, without impairment of haemodynamics. Additional studies should be initiated to confirm these observations.

Diagnostic values of CD64, C-reactive protein and procalcitonin in ventilator-associated pneumonia in adult trauma patients: a pilot study

BACKGROUND

Ventilator-associated pneumonia (VAP) is one of the most common nosocomial infections; however, its diagnosis remains difficult to establish in the critical care setting. We investigated the potential role of neutrophil CD64 (nCD64) expression as an early marker for the diagnosis of VAP.

METHODS

Forty-nine consecutive patients with clinically suspected VAP were prospectively included in a single-center study. The levels of nCD64, C-reactive protein (CRP), and serum procalcitonin (PCT) were analyzed for diagnostic evaluation at the time of intubation (baseline), at day 0 (time of diagnosis), and at day 3. The receiver operating characteristic curves were analyzed to identify the ideal cutoff values.

RESULTS

VAP was confirmed in 36 of 49 cases. In patients with and without VAP, the median levels (interquartile range, IQR) of nCD64 did not differ either at baseline [2.4 (IQR, 1.8-3.1) and 2.6 (IQR, 2.3-3.2), respectively; p=0.3] or at day 0 [2 (IQR, 2.5-3.0) and 2.6 (IQR, 2.4-2.9), respectively; p=0.8]. CRP showed the largest area under the curve (AUC) at day 3. The optimum cutoff value for CRP according to the maximum Youden index was 133 mg/dL. This cutoff value had 69% sensitivity and 76% specificity for predicting VAP; the AUC was 0.73 (95% CI, 0.59-0.85). The nCD64 and PCT values could not discriminate between the VAP and non-VAP groups either at day 0 or day 3.

CONCLUSIONS

The results of this pilot study suggest that neutrophil CD64 measurement has a poor role in facilitating the diagnosis of VAP and thus may not be practically recommended to guide the administration of antibiotics when VAP is suspected.

BreathDx - molecular analysis of exhaled breath as a diagnostic test for ventilator-associated pneumonia: protocol for a European multicentre observational study

BACKGROUND

The diagnosis of ventilator-associated pneumonia (VAP) remains time-consuming and costly, the clinical tools lack specificity and a bedside test to exclude infection in suspected patients is unavailable. Breath contains hundreds to thousands of volatile organic compounds (VOCs) that result from host and microbial metabolism as well as the environment. The present study aims to use breath VOC analysis to develop a model that can discriminate between patients who have positive cultures and who have negative cultures with a high sensitivity.

METHODS/DESIGN

The Molecular Analysis of Exhaled Breath as Diagnostic Test for Ventilator-Associated Pneumonia (BreathDx) study is a multicentre observational study. Breath and bronchial lavage samples will be collected from 100 and 53 intubated and ventilated patients suspected of VAP. Breath will be analysed using Thermal Desorption - Gas Chromatography - Mass Spectrometry (TD-GC-MS). The primary endpoint is the accuracy of cross-validated prediction for positive respiratory cultures in patients that are suspected of VAP, with a sensitivity of at least 99% (high negative predictive value).

DISCUSSION

To our knowledge, BreathDx is the first study powered to investigate whether molecular analysis of breath can be used to classify suspected VAP patients with and without positive microbiological cultures with 99% sensitivity.

TRIAL REGISTRATION

UKCRN ID number 19086, registered May 2015; as well as registration at www.trialregister.nl under the acronym 'BreathDx' with trial ID number NTR 6114 (retrospectively registered on 28 October 2016).

Can we improve clinical outcomes in patients with pneumonia treated with antibiotics in the intensive care unit?

INTRODUCTION

Pneumonia in the intensive care unit (ICU) is associated with high morbidity, mortality and healthcare costs. However, treatment outcomes with conventional intravenous (IV) antibiotics remain suboptimal, and there is an urgent need for improved therapy options.

AREAS COVERED

We review how clinical outcomes in patients with pneumonia treated in the ICU could be improved; we discuss the importance of choosing appropriate outcome measures in clinical trials, highlight the current suboptimal outcomes in patients with pneumonia, and outline potential solutions. We have included key studies and papers based on our clinical expertise, therefore a systematic literature review was not conducted. Expert commentary: Reasons for poor outcomes in patients with nosocomial pneumonia in the ICU include inappropriate initial therapy, increasing bacterial resistance and the complexities of IV dosing in critically ill patients. Robust clinical trial endpoints are needed to enable an accurate assessment of the success of new treatment approaches, but progress in this field has been slow. In addition, only very few new antimicrobials are currently in development for nosocomial pneumonia; two potential alternative solutions to improve outcomes could therefore include the optimization of pharmacokinetic/pharmacodynamics (PK/PD) and dosing of existing therapies, and the refinement of antimicrobial delivery by inhalation.

Witnessed aspiration in trauma: Frequent occurrence, rare morbidity--A prospective analysis

BACKGROUND

Aspiration events (AEs) are a well-recognized complication in trauma patients and have traditionally been considered a risk factor for pneumonia. Despite this, there is no consensus on the incidence or clinical significance of AE in the trauma population.

METHODS

All patients admitted as trauma team activations at our Level I trauma center who were intubated in the field or on arrival from September 2013 to August 2014 were prospectively collected. Field and admission data including witnessed AEs were analyzed. Additional hospital data included imaging, associated injuries, laboratory, and clinical data. Early respiratory failure, pneumonia, and hospital mortality were collected.

RESULTS

During the study period, 228 patients met inclusion criteria. Median age was 35.5 years, and Injury Severity Score (ISS) was 21.0. Overall, 58 patients (25.4%) had witnessed AEs. Patients with AE had significantly higher ISS (26.0 vs. 17.0, p = 0.027) and lower Glasgow Coma Scale (GCS) score on admission (median, 4.0 vs. 7.0; p = 0.003), despite similar field GCS score (p = 0.946). Body mass index (median, 27.2 vs. 26.2; p = 0.374) and intoxication rates (86.2% vs. 83.5%, p = 0.835) were similar between groups. Early pneumonia and respiratory failure were rare in all patients and were not higher in those with AE. Although mortality was higher after AE in patients who died directly after admission (51.7% vs. 30.0%, p = 0.004), in patients who survived to intensive care unit admission, there was no longer a difference between groups and aspiration was not an independent predictor of mortality (p = 0.107) on multivariable regression analysis.

CONCLUSION

The rate of aspiration in trauma is high and more likely to occur in patients with increased injury burden or depressed GCS score. In patients who survive past admission, early pneumonia rates are similar, regardless of AE. These data suggest that aspiration is a marker of severe illness and is associated with but not an independent predictor of mortality.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Clinical significance of ventilator-associated event

PURPOSE

A novel surveillance algorithm of ventilator-associated event (VAE) was introduced to overcome the subjectivity of conventional ventilator-associated pneumonia. We investigated the risk factors and prognostic values of VAE.

METHODS

We conducted a retrospective study of 869 patients treated with mechanical ventilation for greater than or equal to 2 calendar days from January 2013 to June 2014. We compared the episodes of mechanical ventilation with or without VAE and analyzed risk factors and clinical outcomes of VAE.

RESULTS

Among 1031 episodes of mechanical ventilation, 92 episodes were complicated with VAE. VAE occurred more frequently when the initial causes of mechanical ventilation were trauma (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.1-6.3) and pulmonary edema (OR, 2.4; 95% CI, 1.2-4.7). VAE was significantly associated with prolonged mechanical ventilation (5 vs 12 days; P<.001), reduced rate of successful extubation (50.1% vs 17.5%; P<.001), and increased 30-day mortality (35.6% vs 74.2%; P<.001). VAE was a significant risk factor of 30-day mortality on multivariate regression analysis (OR, 3.6; 95% CI, 2.0-6.6; P<.001).

CONCLUSIONS

Patients treated with mechanical ventilation due to pulmonary edema or trauma had increased risk of VAE, with its development indicative of adverse clinical outcomes.

Internal and External Validation of a multivariable Model to Define Hospital-Acquired Pneumonia After Esophagectomy

BACKGROUND

Pneumonia is an important complication following esophagectomy; however, a wide range of pneumonia incidence is reported. The lack of one generally accepted definition prevents valid inter-study comparisons. We aimed to simplify and validate an existing scoring model to define pneumonia following esophagectomy.

PATIENTS AND METHODS

The Utrecht Pneumonia Score, comprising of pulmonary radiography findings, leucocyte count, and temperature, was simplified and internally validated using bootstrapping in the dataset (n = 185) in which it was developed. Subsequently, the intercept and (shrunk) coefficients of the developed multivariable logistic regression model were applied to an external dataset (n = 201) RESULTS: In the revised Uniform Pneumonia Score, points are assigned based on the temperature, the leucocyte, and the findings of pulmonary radiography. The model discrimination was excellent in the internal validation set and in the external validation set (C-statistics 0.93 and 0.91, respectively); furthermore, the model calibrated well in both cohorts.

CONCLUSION

The revised Uniform Pneumonia Score (rUPS) can serve as a means to define post-esophagectomy pneumonia. Utilization of a uniform definition for pneumonia will improve inter-study comparability and improve the evaluations of new therapeutic strategies to reduce the pneumonia incidence.

No Decrease in Early Ventilator-Associated Pneumonia After Early Use of Chlorhexidine

BACKGROUND

Oral chlorhexidine prophylaxis can decrease occurrence of ventilator-associated pneumonia. However, the importance of timing has never been fully explored.

OBJECTIVE

To see if early administration of oral chlorhexidine is associated with lower incidence of early ventilator-associated pneumonia (within 5 days of admission to intensive care unit) in intubated air ambulance patients.

METHODS

A single-center, retrospective cohort study of intubated adults transported by a university-based air ambulance service and admitted to a surgical intensive care unit from July 2011 through April 2013. Primary exposure was time from helicopter retrieval to the first dose of oral chlorhexidine in the intensive care unit. Early chlorhexidine was defined as receipt of the drug within 6 hours of helicopter departure. The primary outcome was clinical diagnosis of early ventilator-associated pneumonia. Patients who were less than 18 years old, died within 72 hours of admission, or had pneumonia at admission were excluded.

RESULTS

Among 134 patients, 49% were treated with chlorhexidine before 6 hours, 84% were treated before 12 hours, and 11% were treated for early pneumonia. Early chlorhexidine (before 6 hours; 15%) was not associated (P = .21) with early pneumonia (8%). Furthermore, median times to chlorhexidine did not differ significantly (P = .23) between patients in whom pneumonia developed (5.2 hours) and patients with no pneumonia (6.1 hours).

CONCLUSIONS

Early administration of oral chlorhexidine in intubated patients was not associated with a reduction in the incidence of ventilator-associated pneumonia in a surgical intensive care unit with high rates of chlorhexidine administration before 12 hours.

Ventilator-associated pneumonia in critically ill patients with intensive antibiotic usage

Objective:

Ventilator-associated pneumonia (VAP) is an infection with high mortality and morbidity that prolongs the length of stay in the intensive care unit (ICU) and hospitalisation. VAP is one of the most common infections in critically ill patients. This study aimed to prospectively determine the VAP rate and associated factors in critically ill patients with intensive antibiotic usage during a one-year period.

Methods:

In total, 125 out of 360 patients admitted to the intensive care unit during the one-year study period (September 2010-2011) were included for follow-up for VAP diagnosis. Demographic data, APACHE II scores, diagnoses on admission, clinical pulmonary infection scores (CPIS), CRP, procalcitonin, risk factors for infection, time to VAP diagnosis, and bacteriological culture results were recorded. All data were assessed in terms of ICU, hospital and 28-day mortality.

Results:

In total, 56 (45%) out of 125 patients were diagnosed with VAP. In addition, 91% of patients diagnosed with VAP were administered antibiotics before diagnosis. In the VAP patients, the mortality rates were 48, 68 and 71% for 28-day, ICU and hospital mortality, respectively.

Conclusion:

The coexistence of clinical and microbiological parameters should not be sought when diagnosing VAP in patients who use antibiotics intensively. VAP can be diagnosed when CPIS≤6 in cases with sufficient microbiological evidence. This strategy may decrease mortality by preventing a delay in therapy.

Elevated Plasma Matrix Metalloproteinase-9 and Its Correlations with Severity of Disease in Patients with Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) increases patient mortality and medical expenditure, and a real-time and reliable method for the rapid diagnosis of VAP may help reduce fatal complications. Matrix metalloproteinases-9 (MMP-9) is considered significant in the pathogenesis of lung inflammation and infection. Therefore, we examined its relationship with the clinical course of VAP. This retrospective observational study recruited 30 healthy volunteers, 12 patients who used mechanical ventilation without the development of VAP (hereafter, patients without VAP), and 30 patients with a clinical diagnosis of VAP (hereafter, patients with VAP). The activity and level of plasma MMP-9 were determined through a gelatin zymography assay and ELISA. Our results report that both plasma MMP-9 activity and concentration were significantly elevated in the acute stage of patients with VAP when compared with control group and patients without VAP (p < 0.001). Subsequently, the plasma MMP-9 of patients with VAP decreased significantly after antibiotic treatment. Furthermore, plasma MMP-9 concentration was positively correlated with the clinical pulmonary infection score (r = 0.409, p = 0.007), WBCs (r = 0.620, p < 0.001), and neutrophils counts (r = 0.335, p = 0.035). In addition, plasma MMP-9 is an excellent tool for recognizing VAP when the cutoff level is set to 92.62 ng/mL (AUC = 0.863, 95% CI = 0.761 to 0.932). In conclusions, we concluded that MMP-9 levels play a role in the development of VAP and might have the potential to be applied in the development of VAP therapies.

Lack of added predictive value of portable chest radiography in diagnosing ventilator-associated pulmonary infection

INTRODUCTION

The accurate diagnosis of ventilator-associated pulmonary infection (VAPI) poses an ongoing challenge. At our institution, patients in whom VAPI is strongly suspected on the basis of the Clinical Pulmonary Infection Score (CPIS) undergo diagnostic mini-bronchoalveolar lavage (mBAL) with quantitative cultures, followed by empiric antibiotic therapy in our surgical intensive care unit (sICU). We sought to determine the role of portable chest X-radiography (pCXR) in the diagnosis of VAPI.

METHODS

We conducted a retrospective analysis of mechanically ventilated adult (>18 y of age) patients with suspected VAPI undergoing concomitant pCXR and diagnostic mBAL in a combined tertiary-care unit for trauma and surgical intensive care. Portable chest X-radiographs were evaluated in a blinded manner by surgical intensivists, critical care fellows, general surgical residents, and radiologists, and were rated as: (0) Not suspicious for pneumonia, (1) possible pneumonia, or (2) likely pneumonia. These results were compared with the microbiologic results of mBAL culture. Demographic and clinical characteristics including age, gender, white blood cell count (WBC), temperature, purulence of secretions, blood and urine culture results, and length of hospitalization were correlated with the results of mBAL.

RESULTS

Regardless of interpreter specialty or level of training, pCXR had no predictive value for VAPI. The overall sensitivity and specificity of pCXR were 77% and 74%, respectively, and its positive predictive value, negative predictive value, and receiver-operating characteristic (ROC) curve areas all had values below 50%. The inter-rater agreement (ρ) was 0.965, showing little discrepancy between raters. The degree of purulence on mBAL, concurrent blood stream infection, and increase in the number of days of hospitalization before diagnostic testing were correlated with an increased frequency of VAPI. The three CPIS criteria of febrile response, leukocytosis/leukopenia, and arterial oxygenation correlated poorly with the results of mBAL culture.

CONCLUSION

Portable chest X-radiography has no added predictive value in identifying patients who should be evaluated further for VAPI. This supports the elimination of findings on chest X-radiography as defining characteristics of VAP, which accords with the U.S. Centers for Disease Control and Prevention's recent definition of VAP as but one of a number of types of ventilator-associated pulmonary infection (VAPI).

A pilot study of the noninvasive assessment of the lung microbiota as a potential tool for the early diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) remains a common complication in critically ill surgical patients, and its diagnosis remains problematic. Exhaled breath contains aerosolized droplets that reflect the lung microbiota. We hypothesized that exhaled breath condensate fluid (EBCF) in hygroscopic condenser humidifier/heat and moisture exchanger (HCH/HME) filters would contain bacterial DNA that qualitatively and quantitatively correlate with pathogens isolated from quantitative BAL samples obtained for clinical suspicion of pneumonia.

METHODS

Forty-eight adult patients who were mechanically ventilated and undergoing quantitative BAL (n = 51) for suspected pneumonia in the surgical ICU were enrolled. Per protocol, patients fulfilling VAP clinical criteria undergo quantitative BAL bacterial culture. Immediately prior to BAL, time-matched HCH/HME filters were collected for study of EBCF by real-time polymerase chain reaction. Additionally, convenience samples of serially collected filters in patients with BAL-diagnosed VAP were analyzed.

RESULTS

Forty-nine of 51 time-matched EBCF/BAL fluid samples were fully concordant (concordance > 95% by κ statistic) relative to identified pathogens and strongly correlated with clinical cultures. Regression analysis of quantitative bacterial DNA in paired samples revealed a statistically significant positive correlation (r = 0.85). In a convenience sample, qualitative and quantitative polymerase chain reaction analysis of serial HCH/HME samples for bacterial DNA demonstrated an increase in load that preceded the suspicion of pneumonia.

CONCLUSIONS

Bacterial DNA within EBCF demonstrates a high correlation with BAL fluid and clinical cultures. Bacterial DNA within EBCF increases prior to the suspicion of pneumonia. Further study of this novel approach may allow development of a noninvasive tool for the early diagnosis of VAP.

Screening for Ventilator-Associated Pneumonia in the Surgical Intensive Care Unit: A Single-Institution Analysis of 1,013 Lower Respiratory Tract Cultures

BACKGROUND

Refinement of criteria for both screening and initiation of empiric therapy in ventilator-associated pneumonia (VAP) will minimize antibiotic overuse. We hypothesized that variables within the commonly used Clinical Pulmonary Infection Score (CPIS) have unfavorable test performance characteristics.

METHODS

Consecutive bronchoalveolar lavage (BAL) cultures obtained from surgical intensive care unit patients were abstracted (2009-2012). Ventilator-associated pneumonia was defined as ≥10(5) cfu/mL. The CPIS both without (CPISclinical) and with (CPISclinical+GS) the result of gram stain (GS) was calculated. Test performance characteristics for the sample, as well as several subgroups, were compared.

RESULTS

One thousand thirteen lower respiratory tract cultures from 492 patients were analyzed; 438 (43.2%) of cultures were classified as VAP, and 310 of 492 patients (62.4%) had ≥1 episode of VAP. Both CPISclinical and CPISclinical+GS had poor discrimination for VAP (Receiver-operating characteristic area under the curve=0.55 and 0.66, respectively). Sensitivity of CPISclinical using a threshold of >6 was 21%; the lowest threshold for CPISclinical for which the sensitivity was at least 85% was 3. The highest sensitivity among the individual CPIS components was new CXR infiltrate (91.1%). Among the subset of cultures sent during the early VAP window (days intubated 2-5), organisms on GS had a sensitivity of 93.3%. The CPISclinical, CPISclinical+GS, organisms, and neutrophils on GS parameters all became less accurate in both the late VAP window and when screening for recurrent VAP. Every case of VAP had at least one of the following: 1) fever; 2) new CXR infiltrate, or 3) organisms on GS.

CONCLUSION

In this series of BALs, traditional screening tools for VAP missed the majority of microbiological confirmed cases. Screening based on either new CXR infiltrate or fever yielded an acceptably high sensitivity. The only scenario identified in which empiric antibiotics could be withheld safely was the absence of organisms on GS in the early VAP window.

Impact of diagnostic criteria on the incidence of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is a frequent complication of prolonged invasive ventilation. Because VAP is largely preventable, its incidence has been used as an index of quality of care in the ICU. However, the incidence of VAP varies according to which criteria are used to identify it. We compared the incidence of VAP obtained with different sets of criteria.

METHODS

We collected data from all adult patients admitted to our 35-bed ICU over a 7-month period who had no pulmonary infection on admission or within the first 48 h and who required mechanical ventilation for > 48 h. To diagnose VAP, we applied six published sets of criteria and 89 combinations of criteria for hypoxemia, inflammatory response, purulence of tracheal secretions, chest radiography findings, and microbiologic findings of varying levels of severity. The variables used in each diagnostic algorithm were assessed daily.

RESULTS

Of 1,824 patients admitted to the ICU during the study period, 91 were eligible for inclusion. The incidence of VAP ranged from 4% to 42% when using the six published sets of criteria and from 0% to 44% when using the 89 combinations. The delay before diagnosis of VAP increased from 4 to 8 days with increasingly stringent criteria, and mortality increased from 50% to 80%.

CONCLUSIONS

Applying different diagnostic criteria to the same patient population can result in wide variation in the incidence of VAP. The use of different criteria can also influence the time of diagnosis and the associated mortality rate.

Validation of predictors of adverse outcomes in hospital-acquired pneumonia in the ICU

OBJECTIVE

To validate a set of predictors of adverse outcomes in patients with ICU-acquired pneumonia in relation to clinically relevant assessment at 28 days.

DESIGN

Prospective, observational study.

SETTING

Six medical and surgical ICUs of a university hospital.

PATIENTS

Three hundred thirty-five patients with ICU-acquired pneumonia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Development of predictors of adverse outcomes was defined when at least one of the following criteria was present at an evaluation made 72-96 hours after starting treatment: no improvement of PaO2/FIO2, need for intubation due to pneumonia, persistence of fever or hypothermia with purulent respiratory secretions, greater than or equal to 50% increase in radiographic infiltrates, or occurrence of septic shock or multiple organ dysfunction syndrome. We also assessed the inflammatory response by different serum biomarkers. The presence of predictors of adverse outcomes was related to mortality and ventilator-free days at day 28. Sequential Organ Failure Assessment score was evaluated and related to mortality at day 28.One hundred eighty-four (55%) patients had at least one predictor of adverse outcomes. The 28-day mortality was higher for those with versus those without predictors of adverse outcomes (45% vs 19%, p<0.001), and ventilator-free days were lower (median [interquartile range], 0 [0-17] vs 22 [0-28]) for patients with versus patients without predictors of adverse outcomes (p<0.001). The lack of improvement of PaO2/FIO2 and lack of improvement in Sequential Organ Failure Assessment score from day 1 to day 5 were independently associated with 28-day mortality and fewer ventilator-free days. The marginal structural analysis showed an odds ratio of death 2.042 (95% CI, 1.01-4.13; p=0.047) in patients with predictors of adverse outcomes. Patients with predictors of adverse outcomes had higher serum inflammatory response accordingly to biomarkers evaluated.

CONCLUSIONS

The presence of any predictors of adverse outcomes was associated with mortality and decreased ventilator-free days at day 28. The lack of improvement in the PaO2/FIO2 and Sequential Organ Failure Assessment score was independently associated with mortality in the multivariate analysis.

[Nosocomial pneumonia]

The hospital acquired pneumonia (HAP) is one of the most common infections acquired among hospitalised patients. Within the HAP, the ventilator-associated pneumonia (VAP) is the most common nosocomial infection complication among patients with acute respiratory failure. The VAP and HAP are associated with increased mortality and increased hospital costs. The rise in HAP due to antibiotic-resistant bacteria also causes an increase in the incidence of inappropriate empirical antibiotic therapy, with an associated increased risk of hospital mortality. It is very important to know the most common organisms responsible for these infections in each hospital and each Intensive Care Unit, as well as their antimicrobial susceptibility patterns, in order to reduce the incidence of inappropriate antibiotic therapy and improve the prognosis of patients. Additionally, clinical strategies aimed at the prevention of HAP and VAP should be employed in hospital settings caring for patients at risk for these infections.

Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) as a diagnostic marker of ventilator-associated pneumonia

OBJECTIVE

To determine the utility of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) levels in bronchoalveolar lavage fluid (BALF) and exhaled breath condensate (EBC) samples from patients who underwent bronchoscopy for a clinical suspicion of ventilator-associated pneumonia (VAP), to categorize patients as VAP positive and VAP negative, when compared to quantitative culture results of BALF.

METHODS

Observational study conducted on admitted patients in the trauma-surgical, medical-cardiac, burn, and neurosurgical ICUs of Harborview Medical Center between March 2009 and May 2010. BALF and EBC samples were obtained from 45 patients with clinically suspected VAP. Bronchoscopy was performed on the day of clinically suspected VAP. sTREM-1 levels in EBC and BAL fluid were measured using quantikine human TREM-1 immunoassay. VAP was diagnosed by quantitative cultures of BALF.

RESULTS

The concentrations of sTREM-1 in BALF and EBC did not correlate with VAP status. sTREM-1 levels did not discriminate VAP positive from VAP negative patients, when compared to quantitative cultures of BALF as the gold standard. Using a cutoff value of 204 pg/mL for BALF sTREM-1 levels resulted in a sensitivity of 79% and a specificity of 23%. A cutoff value of 10 pg/mL for EBC sTREM-1 levels resulted in a sensitivity of 42% and a specificity of 50%.

CONCLUSIONS

EBC and BALF sTREM-1 levels did not effectively categorize patients as VAP positive or VAP negative when using direct bronchoscopic quantitative culture samples as the comparison standard.

A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia

Healthcare-associated pneumonia (HCAP) guidelines recommend de-escalating initial antibiotic therapy based on results from lower-respiratory-tract cultures. In the absence of adequate lower respiratory cultures, physicians are sometimes reluctant to discontinue empirical vancomycin, which is given for suspected methicillin-resistant Staphylococcus aureus (MRSA) HCAP. We evaluated a strategy of discontinuing vancomycin if both nasal and throat cultures were negative for MRSA when lower-respiratory-tract cultures were not available. An antimicrobial stewardship team identified patients receiving empirical vancomycin for suspected or proven HCAP but for whom adequate lower-respiratory-tract cultures were not available. Nasal and throat swab specimens were obtained and plated on MRSA selective media. If both nasal and throat MRSA cultures were negative, the stewardship team recommended discontinuation of empirical vancomycin. Demographic and clinical aspects, a clinical pulmonary infection score (CPIS) on the day of the stewardship recommendation, and mortality of patients for whom vancomycin was discontinued were obtained by retrospective chart review. A convenience sample of 91 patients with nasal and throat cultures negative for MRSA in the absence of adequate respiratory cultures had empirical vancomycin therapy discontinued. A retrospective review revealed that 88 (97%) patients had a CPIS of ≤6 on the day of the stewardship recommendation. In-hospital mortality (7.7%) was similar to that of a previous study of de-escalation of antibiotics in pneumonia patients without adequate cultures. In the absence of adequate lower-respiratory-tract cultures, it is reasonable to discontinue empirical vancomycin HCAP therapy in patients with negative MRSA nasal and throat cultures and a CPIS of <6.

Bilateral versus unilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) complicates the clinical course of critically injured intubated patients. Bronchoscopic bronchoalveolar lavage (BAL) represents an invasive and accurate means of VAP diagnosis. Unilateral and blinded techniques offer less invasive alternatives to bronchoscopic BAL. This study evaluated clinical criteria as well as unilateral directed versus bilateral BAL for VAP diagnosis.

METHODS

A retrospective chart review of 113 consecutive intubated trauma patients with clinically suspected VAP undergoing unilateral versus bilateral BAL was performed with comparison of positive culture results (>10(4) colony-forming units [CFU]/mL). Culture results were compared with chest radiograph (CXR) infiltrates and white blood cell (WBC) count elevation.

RESULTS

Bilateral BAL was more likely to be positive than unilateral BAL (50.4% vs. 25.5%). In 37.1% of bilateral BALs, there was discordance between the sides of positivity or the bacteria isolated. A CXR infiltrate and WBC count elevation did not predict positive BAL.

CONCLUSIONS

Clinical indicators of VAP are inaccurate, and bilateral bronchoscopic BAL is more likely than unilateral BAL to provide a positive sample in intubated trauma patients. Techniques that do not sample both lungs reliably should be avoided for diagnosis in this patient population.

Use of the clinical pulmonary infection score to guide therapy for ventilator-associated pneumonia risks antibiotic overexposure in patients with trauma

BACKGROUND

The clinical pulmonary infection score (CPIS) has been advocated to guide both the diagnosis and duration of therapy in ventilator-associated pneumonia (VAP). However, the clinical, physiologic, and radiologic components of the CPIS may be difficult to differentiate from the systemic effects of injury and inflammation, unnecessarily prolonging VAP therapy. This study evaluates the use of CPIS in determining the appropriate duration of antimicrobial therapy for VAP in patients with critical illness and trauma.

METHODS

Patients with VAP (≥10 CFU/mL in bronchoalveolar lavage [BAL] effluent) over 6 years were evaluated. Duration of antimicrobial therapy was determined by microbiologic resolution (≤10 CFU/mL) on repeated BAL. Recurrence was defined as >10 CFU/mL on BAL performed within 2 weeks of appropriate therapy. A CPIS of less than 6 was used as a threshold for VAP resolution.

RESULTS

Of the patients with VAP, 1,028 were identified: 523 had community-acquired pathogens (mean CPIS, 6.9), and 505 had hospital-acquired (HA) pathogens (mean CPIS, 6.3). Using a CPIS of less than 6 yielded a sensitivity and specificity of 69% and 51% for community-acquired pathogens and 72% and 53% for HA pathogens, respectively. Antimicrobial therapy would have continued inappropriately in 59% of patients. Overall recurrence was 1%, occurring only with HA pathogens (mean CPIS, 5.9).

CONCLUSION

CPIS should not be used to determine VAP resolution in patients with critical injury and trauma. It cannot reliably differentiate VAP from the systemic inflammatory response syndrome in the face of confounding clinical factors. Using CPIS to determine appropriate duration of antimicrobial therapy for patients with trauma is costly and could be harmful by unnecessarily prolonging exposure to antibiotics.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Identifying missed opportunities to curtail antimicrobial therapy for presumed ventilator-associated pneumonia using the clinical pulmonary infection score

BACKGROUND

Early discontinuation of antimicrobial therapy for ventilator-associated pneumonia can reduce the emergence of antimicrobial resistance, the occurrence of adverse drug events, and the cost of therapy. Evidence suggests that discontinuation of therapy by day 3 may be appropriate for patients with a clinical pulmonary infection score of 6 or less at baseline and on day 3.

OBJECTIVES

To determine the proportion of patients eligible for antimicrobial discontinuation on day 3 and day 7 of therapy and to determine the proportion of eligible patients for whom antimicrobials were discontinued within these timeframes.

METHODS

A 6-month observational study was conducted from October 3, 2005, to March 31, 2006, in a 27-bed medical-surgical tertiary care intensive care unit. Clinical pharmacists attended daily rounds and prospectively identified patients for inclusion in the study. A study pharmacist retrospectively calculated clinical pulmonary infection scores. Other data were obtained from the quality-improvement database and patient health records for the intensive care unit.

RESULTS

Ninety-two patients were treated for ventilator-associated pneumonia during the study period, of whom 49 were included in the analysis. At day 3, 17 (35%) of the 49 patients were eligible for early discontinuation of antimicrobial therapy, but therapy was discontinued for only 2 (12%) of these 17 patients. At day 7, 10 (32%) of 31 patients were eligible for antimicrobial discontinuation, but therapy was discontinued for only 1 (10%) of these 10 patients.

CONCLUSIONS

A significant opportunity exists at the authors' institution to develop and implement an antimicrobial discontinuation policy that uses the clinical pulmonary infection score to guide antimicrobial use for patients with ventilator-associated pneumonia.

Empiric antibiotics pending bronchoalveolar lavage data in patients without pneumonia significantly alters the flora, but not the resistance profile, if a subsequent pneumonia develops

INTRODUCTION

Ventilator-associated pneumonia (VAP) occurs in up to 25% of mechanically ventilated patients, with an associated mortality up to 50%. Early diagnosis and appropriate empiric antibiotic coverage of VAP are crucial. Given the multitude of noninfectious clinical and radiographic anomalies within trauma patients, microbiology from bronchioalveolar lavage (BAL) is often needed. Empiric antibiotics are administered while awaiting BAL culture data. Little is known about the effects of these empiric antibiotics on patients with negative BAL microbiology if a subsequent VAP occurs during the same hospital course.

METHODS

This is a retrospective chart review of intubated trauma patients undergoing BAL for suspected pneumonia over a 3-y period at a Level 1 trauma center. All patients with suspected VAP undergoing a BAL receive empiric antibiotics. If microbiology data are negative at 72 h, all antibiotics are stopped; however, if the BAL returns with ≥10(5) colony-forming units per milliliter, the diagnosis of VAP is confirmed. We divided patients into three groups. Group 1 consisted of patients in whom the initial BAL was positive for VAP. Group 2 consisted of patients with an initial negative BAL, who subsequently developed VAP at a later point in the hospital course. Group 3 consisted of patients with negative BAL who did not develop a subsequent VAP.

RESULTS

We obtained 499 BAL specimens in 185 patients over the 3-y period. A total of 14 patients with 23 BAL specimens initially negative for VAP subsequently developed VAP later during the same hospital stay. These patients did not have an increase in the hospital length of stay, intensive care unit days, ventilator days, or mortality compared with those who had a positive culture on the first suspicion of VAP. There was a significant increase in the percentage of Enterobacter (21% versus 8%) and Morganella (8% versus 0%) as the causative organism in these 14 patients when the VAP occurred. Furthermore, the profile of the top two organisms in each group changed. Enterobacter (21%) and Pseudomonas (17%) were the principal organisms in the initial BAL-negative group, whereas the two predominant strains in the initial positive BAL group were methicillin-sensitive Staphylococcus aureus (21%) and Haemophilus influenza (11%). Interestingly, methicillin-resistant S. aureus remained the third most common organism in both groups. Empiric antibiotics also did not seem to induce the growth of multidrug-resistant organisms, and there was no increased rate of secondary infections such as Clostridium difficile.

CONCLUSIONS

Ventilator-associated pneumonia remains a significant cause of morbidity and mortality in mechanically ventilated trauma patients. The diagnosis and treatment of VAP continue to be challenging. Once clinically suspected, empiric coverage decreases morbidity and mortality. Our data demonstrate that patients who receive empiric coverage exhibit a significantly different microbiologic profile compared with those who had an initial positive BAL culture. Initial empiric antibiotics in BAL-negative patients were not associated with an increase in multidrug-resistant organisms, hospital, or intensive care unit length of stay, ventilator days, and mortality or secondary infections.

Ventilator-associated pneumonia in burn patients: a cause or consequence of critical illness?

Infectious complications are a constant threat to thermally injured patients during hospitalizations and are a predominant cause of death. Most of the infections that develop in burn patients are nosocomial and of a pulmonary etiology. The bacteria that cause ventilator associated pneumonia (VAP) take advantage of the fact that uniquely among intensive care unit patients endotracheal intubation allows them a 'free' passage to the sterile lower airways; however, the combination of severe thermal injury (systemic immunosuppression) and inhalation injury (local immunosuppression and tissue injury) create an ideal environment for development of VAP. Thus, strategies directed at preventing and treating VAP in burn patients must address not only rapid extubation and VAP prevention bundles known to work in other intensive care unit populations, but therapies directed to more rapid wound healing and restoration of pulmonary patency.

Comparison of bronchoscopic and non-bronchoscopic techniques for diagnosis of ventilator associated pneumonia

Background:

The diagnosis of ventilator associated pneumonia (VAP) remains a challenge because the clinical signs and symptoms lack both sensitivity and specificity and the selection of microbiologic diagnostic procedure is still a matter of debate.

Aims and Objective:

To study the role of various bronchoscopic and non-bronchoscopic diagnostic techniques for diagnosis of VAP.

Settings and Design:

This prospective comparative study was conducted in a medical ICU of a tertiary care center.

Materials and Methods:

Twenty-five patients, clinically diagnosed with VAP, were evaluated by bronchoscopic and non-bronchoscopic procedures for diagnosis. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of various bronchoscopic and non-bronchoscopic techniques were calculated, taking clinical pulmonary infection score (CPIS) of ≥6 as reference standard.

Results:

Our study has shown that for the diagnosis of VAP, bronchoscopic brush had a sensitivity, specificity, PPV and NPV of 94.9% [confidence interval (CI): 70.6–99.7], 57.1% (CI: 13.4–86.1), 85% (CI: 61.1–96) and 80% (CI: 21.9–98.7), respectively. Bronchoscopic bronchoalveolar lavage (BAL) had a sensitivity, specificity, PPV and NPV of 77.8% (CI: 51.9–92.6), 71.8% (CI: 24.1–94), 87.3% (CI: 60.4–97.8) and 55.5% (CI: 17.4–82.6), respectively. Sensitivity, specificity, PPV and NPV for non–bronchoscopic BAL (NBAL) were 83.3% (CI: 57.7–95.6), 71.43% (CI: 24.1–94), 88.2% (CI: 62.3–97.4) and 62.5% (CI: 20.2–88.2), respectively. Endotracheal aspirate (ETA) yield was only 52% and showed poor concordance with BAL (κ-0.351; P-0.064) and NBAL (k-0.272; P-0.161). There was a good microbiologic concordance among different bronchoscopic and non-bronchoscopic distal airway sampling techniques.

Conclusion:

NBAL is an inexpensive, easy, and useful technique for microbiologic diagnosis of VAP. Our findings, if verified, might simplify the approach for the diagnosis of VAP.

Trauma-associated pneumonia in adult ventilated patients

BACKGROUND

The clinical pulmonary infection score (CPIS) and bronchoalveolar lavage (BAL) are 2 tools that have been validated to diagnose pneumonia in critically ill patients. However, the role of the CPIS in diagnosing trauma-associated pneumonia (TAP) remains in question.

METHODS

This prospective observational study included all trauma patients who were ventilated for longer than 48 hours from September 2008 to September 2009. The CPIS and quantitative culture results from the BAL were collected and used to define pneumonia.

RESULTS

A total of 162 patients were identified. In all, 58 (35.8%) and 104 (64.2%) had a CPIS greater than 5 and a CPIS of 5 or less, respectively. There were 95 (58.6%) patients who had a BAL completed regardless of CPIS. There were 65 patients who met the bacteriologic definition of pneumonia (≥10(4) colonies/mL), for an overall TAP incidence of 40.1%.

CONCLUSIONS

The CPIS is unreliable as a clinical tool to predict a positive BAL at 10(4) or 10(5) or higher threshold. Therefore, BAL should be used for the diagnosis of TAP based on clinical rationale and not the CPIS.

Biomarkers for ventilator-associated pneumonia: review of the literature

OBJECTIVE

Ventilator-associated pneumonia (VAP) contributes significantly to morbidity and mortality in critically ill patients, but it can be difficult to diagnose. Clinical criteria, Clinical Pulmonary Infection Score, and quantitative culture of bronchoalveolar lavage have been used to distinguish between patients who are likely positive (sensitivity) and patients who are likely negative (specificity). Despite these test methods, patients continue to be misclassified. False-positive results may lead to inappropriate antibiotic use in patients. For those misclassified as test negative, appropriate treatment may be delayed. Biomarkers have been suggested as another method to enhance the ability to predict VAP. This article analyzes the evidence for the usefulness of 3 biomarkers that have been proposed as possible biomarkers of VAP: soluble triggering receptor expressed on myeloid type 1 cells, procalcitonin, and C-reactive protein.

METHODS

A Medline search was conducted for the years between 1990 and 2009 to locate articles on the subject of biomarkers for predicting VAP in critically ill adult patients.

RESULTS

Analysis of the literature does not currently support a clinical role for these biomarkers in predicting VAP. Variations in the diagnostic methods, antimicrobial use, cutoff values, and patient populations limit comparisons among the studies.

CONCLUSION

Recommendations are offered to strengthen and standardize methods in future studies to clarify the utility of biomarkers for predicting VAP in specific patient populations.

The relationship between post-traumatic ventilator-associated pneumonia outcomes and American College of Surgeons trauma centre designation

INTRODUCTION

The relationship between outcomes following severe trauma and American College of Surgeons (ACS) trauma centre designation has been studied. Little is known, however, about the association between ACS level and outcomes associated with ventilator-associated pneumonia (VAP).

METHODS

The National Trauma Databank (NTDB, Version 5.0) was queried to identify adult (age 18)trauma patients who (1) developed VAP and (2) were admitted to either an ACS level I or level II centre.Transfer and burn patients were excluded. Univariate analysis defined differences between patient cohorts. Logistic regression analysis was utilised to identify independent risk factors for mortality.

RESULTS

A total of 3465 patients were identified where 65.6% were admitted to a level I facility and 34.4%to a level II centre. Patients admitted to a level I centre were more likely to have an age > 55 (71.5% vs.66.8%, p = 0.004) and to be hypotensive (SBP < 90) on admission (16.2% vs. 13.6%, p = 0.042). They were also more likely to have a longer duration of mechanical ventilation (18.5 days vs. 16.5 days, p = 0.001),longer hospital LOS (34.2 days vs. 29.6 days, p < 0.001) and a higher rate of early (±7 days) tracheostomy(33.1% vs. 29.1%, p = 0.017). Level I admission was, however, associated with lower mortality rates (10.8%vs. 14.7%, p = 0.001) and a higher likelihood of achieving discharge to home (20.2% vs. 16.1%, p < 0.001).Logistic regression analysis identified admission to a level II facility as an independent risk factor for mortality (OR 1.34, 95% CI 1.08–1.66; p = 0.008) in patients developing post-traumatic VAP.

CONCLUSION

For adults who develop VAP after trauma, admission to a level I facility is associated with improved survival. Further prospective study is needed.