Clinical pulmonary infection score for ventilator-associated pneumonia: accuracy and inter-observer variability

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.

Multicenter evaluation of a novel surveillance paradigm for complications of mechanical ventilation

BACKGROUND

Ventilator-associated pneumonia (VAP) surveillance is time consuming, subjective, inaccurate, and inconsistently predicts outcomes. Shifting surveillance from pneumonia in particular to complications in general might circumvent the VAP definition's subjectivity and inaccuracy, facilitate electronic assessment, make interfacility comparisons more meaningful, and encourage broader prevention strategies. We therefore evaluated a novel surveillance paradigm for ventilator-associated complications (VAC) defined by sustained increases in patients' ventilator settings after a period of stable or decreasing support.

METHODS

We assessed 600 mechanically ventilated medical and surgical patients from three hospitals. Each hospital contributed 100 randomly selected patients ventilated 2-7 days and 100 patients ventilated >7 days. All patients were independently assessed for VAP and for VAC. We compared incidence-density, duration of mechanical ventilation, intensive care and hospital lengths of stay, hospital mortality, and time required for surveillance for VAP and for VAC. A subset of patients with VAP and VAC were independently reviewed by a physician to determine possible etiology.

RESULTS

Of 597 evaluable patients, 9.3% had VAP (8.8 per 1,000 ventilator days) and 23% had VAC (21.2 per 1,000 ventilator days). Compared to matched controls, both VAP and VAC prolonged days to extubation (5.8, 95% CI 4.2-8.0 and 6.0, 95% CI 5.1-7.1 respectively), days to intensive care discharge (5.7, 95% CI 4.2-7.7 and 5.0, 95% CI 4.1-5.9), and days to hospital discharge (4.7, 95% CI 2.6-7.5 and 3.0, 95% CI 2.1-4.0). VAC was associated with increased mortality (OR 2.0, 95% CI 1.3-3.2) but VAP was not (OR 1.1, 95% CI 0.5-2.4). VAC assessment was faster (mean 1.8 versus 39 minutes per patient). Both VAP and VAC events were predominantly attributable to pneumonia, pulmonary edema, ARDS, and atelectasis.

CONCLUSIONS

Screening ventilator settings for VAC captures a similar set of complications to traditional VAP surveillance but is faster, more objective, and a superior predictor of outcomes.

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.

Electronic nose analysis of bronchoalveolar lavage fluid

BACKGROUND

Electronic nose (E-nose) technology has been successfully used to diagnose a number of microbial infections. We have investigated the potential use of an E-nose for the diagnosis of ventilator-associated pneumonia (VAP) by detecting micro-organisms in bronchoalveolar lavage (BAL) fluid in a prospective comparative study of E-nose analysis and microbiology.

MATERIALS AND METHODS

BAL samples were collected using a blind technique from 44 patients following a minimum of 72 h mechanical ventilation. Control samples were collected from six patients mechanically ventilated on the intensive care unit (ICU) immediately following elective surgery. Quantitative microbiological culture and E-nose headspace analysis of the BAL samples were undertaken. Multivariate analysis was applied to correlate E-nose response with microbiological growth.

RESULTS

E-nose fingerprints correctly classified 77% of the BAL samples, with and without microbiological growth from patients not on antibiotics. Inclusion of patients on antibiotics resulted in 68% correct classification. Seventy per cent of isolates, cultured in the laboratory from the clinical samples, were accurately discriminated into four clinically significant groups.

CONCLUSIONS

E-nose technology can accurately discriminate between different microbial species in BAL samples from ventilated patients on ICU at risk of developing VAP with accuracy comparable with accepted microbiological techniques.

Recognition and prevention of nosocomial pneumonia in the intensive care unit and infection control in mechanical ventilation

Nosocomial pneumonia (NP) is a difficult diagnosis to establish in the critically ill patient due to the presence of underlying cardiopulmonary disorders (e.g., pulmonary contusion, acute respiratory distress syndrome, atelectasis) and the nonspecific radiographic and clinical signs associated with this infection. Additionally, the classification of NP in the intensive care unit setting has become increasingly complex, as the types of patients who develop NP become more diverse. The occurrence of NP is especially problematic as it is associated with a greater risk of hospital mortality, longer lengths of stay on mechanical ventilation and in the intensive care unit, a greater need for tracheostomy, and significantly increased medical care costs. The adverse effects of NP on healthcare outcomes has increased pressure on clinicians and healthcare systems to prevent this infection, as well as other nosocomial infections that complicate the hospital course of patients with respiratory failure. This manuscript will provide a brief overview of the current approaches for the diagnosis of NP and focus on strategies for prevention. Finally, we will provide some guidance on how standardized or protocolized care of mechanically ventilated patients can reduce the occurrence of and morbidity associated with complications like NP.

Interobserver variability in ventilator-associated pneumonia surveillance

Three infection control personnel and 1 physician independently evaluated 50 ventilated patients for ventilator-associated pneumonia through retrospective chart reviews. The infection control reviewers used Centers for Disease Control and Prevention criteria; the physician used clinical judgment. Infection control personnel labelled between 11 and 20 patients with VAP (kappa = 0.40). The physician diagnosed 7 cases. Interobserver variability in the assessment of ventilator-associated pneumonia is high.

Microbiogical data, but not procalcitonin improve the accuracy of the clinical pulmonary infection score

OBJECTIVE

Early and adequate treatment of ventilator-associated pneumonia (VAP) is mandatory to improve the outcome. The aim of this study was to evaluate, in medical ICU patients, the respective and combined impact of the Clinical Pulmonary Infection Score (CPIS), broncho-alveolar lavage (BAL) gram staining, endotracheal aspirate and a biomarker (procalcitonin) for the early diagnosis of VAP.

DESIGN

Prospective, observational study

SETTING

A medical intensive care unit in a teaching hospital.

PATIENTS

Over an 8-month period, we prospectively included 57 patients suspected of having 86 episodes of VAP.

INTERVENTION

The day of suspicion, a BAL as well as alveolar and serum procalcitonin determinations and evaluation of CPIS were performed.

MEASUREMENTS AND MAIN RESULTS

Of 86 BAL performed, 48 were considered positive (cutoff of 10(4) cfu ml(-1)). We found no differences in alveolar or serum procalcitonin between VAP and non-VAP patients. Including procalcitonin in the CPIS score did not increase its accuracy (55%) for the diagnosis of VAP. The best tests to predict VAP were modified CPIS (threshold at 6) combined with microbiological data. Indeed, both routinely twice weekly performed endotracheal aspiration at a threshold of 10(5) cfu ml(-1) and BAL gram staining improved pre-test diagnostic accuracy of VAP (77 and 66%, respectively).

CONCLUSION

This study showed that alveolar procalcitonin performed by BAL does not help the clinician to identify VAP. It confirmed that serum procalcitonin is not an accurate marker of VAP. In contrast, microbiological resources available at the time of VAP suspicion (BAL gram staining, last available endotracheal aspirate) combined or not with CPIS are helpful in distinguishing VAP diagnosed by BAL from patients with a negative BAL.

The Problems Diagnosing Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is the most common healthcare-associated infection in the intensive care unit. Clinical, radiological and microbiological criteria are used to make the diagnosis, but there is no consensus definition, as no individual criterion or combination of criteria offer sufficient diagnostic accuracy to support their sole use in defining VAP. Neither invasive bronchoscopic sampling nor less invasive quantitative tracheal aspirate, conveys an advantage when making the microbiological diagnosis of VAP. Of the scoring systems and definitions presently in use, the Clinical Pulmonary Infection Score (CPIS) has been shown to be prone to inter-observer variability; the US Centers for Disease Control (CDC) National Healthcare Safety Network (NHSN) definition relies heavily on subjective clinical criteria, and the Hospitals in Europe Link for Infection Control through Surveillance (HELICS) criteria employ similarly subjective clinical criteria with five different possibilities for microbiological diagnosis. The use of these different diagnostic methods leads to marked variation in the reported incidence of VAP. Clinical practice requires an objective and transferable definition for VAP so that we can improve the reporting, monitoring and treatment of VAP.

Serum procalcitonin for the early recognition of nosocomial infection in the critically ill patients: a preliminary report

Background

The usefulness of procalcitonin (PCT) measurement in critically ill medical patients with suspected nosocomial infection is unclear. The aim of the study was to assess PCT value for the early diagnosis of bacterial nosocomial infection in selected critically ill patients.

Methods

An observational cohort study in a 15-bed intensive care unit was performed. Seventy patients with either proven (n = 47) or clinically suspected but not confirmed (n = 23) nosocomial infection were included. Procalcitonin measurements were obtained the day when the infection was suspected (D0) and at least one time within the 3 previous days (D-3 to D0). Patients with proven infection were compared to those without. The diagnostic value of PCT on D0 was determined through the construction of the corresponding receiver operating characteristic (ROC) curve. In addition, the predictive value of PCT variations preceding the clinical suspicion of infection was assessed.

Results

PCT on D0 was the best predictor of proven infection in this population of ICU patients with a clinical suspicion of infection (AUROCC = 0.80; 95% CI, 0.68–0.91). Thus, a cut-off value of 0.44 ng/mL provides sensitivity and specificity of 65.2% and 83.0%, respectively. Procalcitonin variation between D-1 and D0 was calculated in 45 patients and was also found to be predictive of nosocomial infection (AUROCC = 0.89; 95% CI, 0.79–0.98) with a 100% positive predictive value if the +0.26 ng/mL threshold value was applied. Comparable results were obtained when PCT variation between D-2 and D0, or D-3 and D0 were considered. In contrast, CRP elevation, leukocyte count and fever had a poor predictive value in our population.

Conclusion

PCT monitoring could be helpful in the early diagnosis of nosocomial infection in the ICU. Both absolute values and variations should be considered and evaluated in further studies.

Reliability of the medication appropriateness index in Dutch residential home

OBJECTIVE

To validate the reliability of the Medication Appropriateness Index in the appraisal of quality of prescribing by assessing the inter- and intra-group variation in Dutch residential home patients.

SETTING AND METHOD

Eight raters evaluated 81 medication records of 15 patients from a group of older patients living in a residential nursing home The Netherlands. These patients had been recruited for a medication review investigation throughout a period of 12 months over the period April 2003 until April 2004. Patient information was acquired by connecting the medical record with the complete prescription record and pharmaceutical record. Each patient was assessed twice by two independent reviewers on the basis of a patient profile in combination with the extracted medical record and using a structured procedure.

MAIN OUTCOME

A summed MAI score, percent agreement, kappa, positive and negative agreement as well as intra-class correlation coefficient were calculated for each criterion.

MEASURE

Medication appropriateness was assessed with the Medication Appropriateness Index (MAI) by an independent panel of Dutch hospital and community pharmacists.

RESULTS

The overall percentage agreement was 83%. For each of the 10 different medication appropriateness questions it ranged from 79 to 100% for appropriate and from 47 to 60% for inappropriate ratings. The overall chance adjusted inter-rater agreement reached a moderate kappa score of 0.47. The overall intra-group agreement was very good with an overall percentage of 98 and a kappa score of at least 0.84 (all schemes).

CONCLUSION

In a Dutch institutionalised setting with representative raters, the unmodified MAI can be used as an instrument to quantify changes in appropriateness of prescribing.

Ventilator-associated pneumonia in a paediatric intensive care unit in a developing country with high HIV prevalence

AIM

To obtain preliminary prevalence, aetiological and outcome data on South African paediatric patients with ventilator-associated pneumonia (VAP).

METHODS

Non-bronchoscopic bronchoalveolar lavage (BAL) specimens taken between January 2004 and September 2005 were prospectively recorded and related clinical data were retrospectively reviewed. VAP was defined as a new isolate on BAL and a modified Clinical Pulmonary Infection Score > or =5.

RESULTS

A total of 230 patients aged 3.9 (2.2-9.1) months (median interquartile range (IQR) ) underwent 309 BALs during 244 paediatric intensive care unit (PICU) admissions. Most patients (84%) were admitted with acute infectious diseases, with a 70% incidence of comorbidity. Thirty-three patients (14.3%) were HIV-exposed but uninfected and 58 (25.2%) were HIV-infected. Of 172 BALs taken > or =48 h after intubation, 63 specimens from 55 patients fulfilled VAP criteria. Acinetobacter baumannii was the most common VAP pathogen, followed by Klebsiella pneumoniae, viruses, yeasts and Staphylococcus aureus. Patients who developed VAP had a higher proportion of comorbid conditions (76% vs. 55%, P= 0.01) and reintubations (39% vs. 12%, P < 0.0001) when compared with non-VAP patients. Median (IQR) length of PICU stay was 12.5 (5-21) days versus 8 (5-14) days (P= 0.03); and the risk adjusted PICU mortality was 1.38 versus 0.79 (P= 0.002) in VAP versus non-VAP patients, respectively.

CONCLUSIONS

VAP is associated with significant morbidity and mortality and may relate to the high incidence of comorbid conditions in this population. Primary VAP pathogens differ from developed countries.

Strategies to prevent ventilator-associated pneumonia in acute care hospitals

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections. The intent of this document is to highlight practical recommendations in a concise format designed to assist acute care hospitals in implementing and prioritizing their ventilator-associated pneumonia (VAP) prevention efforts. Refer to the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America “Compendium of Strategies to Prevent Healthcare-Associated Infections” Executive Summary and Introduction and accompanying editorial for additional discussion.

1. Occurrence of VAP in acute care facilities.

a. VAP is one of the most common infections acquired by adults and children in intensive care units (ICUs).

i. In early studies, it was reported that 10%-20% of patients undergoing ventilation developed VAP. More-recent publications report rates of VAP that range from 1 to 4 cases per 1,000 ventilator-days, but rates may exceed 10 cases per 1,000 ventilator-days in some neonatal and surgical patient populations. The results of recent quality improvement initiatives, however, suggest that many cases of VAP might be prevented by careful attention to the process of care.

2. Outcomes associated with VAP

a. VAP is a cause of significant patient morbidity and mortality, increased utilization of healthcare resources, and excess cost.

i. The mortality attributable to VAP may exceed 10%.

ii. Patients with VAP require prolonged periods of mechanical ventilation, extended hospitalizations, excess use of antimicrobial medications, and increased direct medical costs.

The utility of the clinical pulmonary infection score

The most common infectious complication in critically ill patients is ventilator-associated pneumonia. Ventilator-associated pneumonia has significant morbidity and mortality, prolongs mechanical ventilation, and extends length of hospitalization. Despite its prevalence and impact, uniform diagnostic standards are lacking. The Centers for Disease Control, American Thoracic Society, and Infectious Diseases Society of America have recommended focus on improving preventive measures, establishing widely available and accurate diagnostic tools, and improving ventilator-associated pneumonia management with length of therapy guidelines. The purpose of this article is to review the evidence supporting the clinical pulmonary infection score as an adjunct to distinguish and detect clinically relevant ventilator-associated pneumonia and its use to guide length of therapy. This score combines clinical diagnostic criteria (tracheal secretion quantification and body temperature) with routinely obtained laboratory data (white blood cell count and oxygenation parameters), radiographic data, and bacteriological culture results. Limitations of clinical pulmonary infection score will be discussed.

Diagnostic implications of soluble triggering receptor expressed on myeloid cells-1 in BAL fluid of patients with pulmonary infiltrates in the ICU

OBJECTIVE

Prospective single-center study to determine whether the presence of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) has diagnostic utility in patients with pulmonary infiltrates receiving mechanical ventilation and undergoing BAL.

DESIGN

Prospective cohort study.

SETTING

Barnes-Jewish Hospital, a 1,200-bed urban teaching hospital.

PATIENTS

Adult patients with acute respiratory failure undergoing BAL for pulmonary infiltrates.

INTERVENTIONS

BAL fluid measurement of sTREM-1 concentration using a Quantikine Human TREM-1 Immunoassay (R&D Systems; Minneapolis, MN).

MEASUREMENTS AND MAIN RESULTS

A total of 105 consecutive patients receiving mechanical ventilation and undergoing BAL were enrolled. Of those, 19 patients (18.1%) met definite microbiologic criteria for bacterial or fungal ventilator-associated pneumonia (VAP). Though the mean sTREM-1 concentration was greater in patients with definite VAP (n = 19; 171.9 +/- 158.7 pg/mL) than in patients with definite absence of VAP (n = 21; 96.7 +/- 76.2 pg/mL), this difference was not statistically significant (p = 0.06). A cutoff value for sTREM-1 > 200 pg/mL yielded a diagnostic sensitivity of 42.1% and a specificity of 75.6% for definite VAP. Patients with alveolar hemorrhage had the greatest values for sTREM-1 concentration (n = 9; 555 +/- 440 pg/mL). Receiver operating curve analysis and multivariate logistic regression analysis demonstrated that measurement of sTREM-1 was inferior to clinical parameters for the diagnosis of VAP.

CONCLUSIONS

Measurement of sTREM-1 in BAL fluid appears to have minimal diagnostic value for VAP.

Evidence-based algorithms for diagnosing and treating ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is widely recognized as a serious and common complication associated with high morbidity and high costs. Given the complexity of caring for heterogeneous populations in the intensive care unit (ICU), however, there is still uncertainty regarding how to diagnose and manage VAP.

OBJECTIVE

We recently conducted a national collaborative aimed at reducing health care-associated infections in ICUs of hospitals operated by the Hospital Corporation of America (HCA). As part of this collaborative, we developed algorithms for diagnosing and treating VAP in mechanically ventilated patients. In the current article, we (1) review the current evidence for diagnosing VAP, (2) describe our approach for developing these algorithms, and (3) illustrate the utility of the diagnostic algorithms using clinical teaching cases.

DESIGN

This was a descriptive study, using data from a national collaborative focused on reducing VAP and catheter-related bloodstream infections.

SETTING

The setting of the study was 110 ICUs at 61 HCA hospitals.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

We assembled an interdisciplinary team that included infectious disease specialists, intensivists, hospitalists, statisticians, critical care nurses, and pharmacists. After reviewing published studies and the Centers for Disease Control and Prevention VAP guidelines, the team iteratively discussed the evidence, achieved consensus, and ultimately developed these practical algorithms. The diagnostic algorithms address infant, pediatric, immunocompromised, and adult ICU patients.

CONCLUSIONS

We present practical algorithms for diagnosing and managing VAP in mechanically ventilated patients. These algorithms may provide evidence-based real-time guidance to clinicians seeking a standardized approach to diagnosing and managing this challenging problem.

Comprehensive evidence-based clinical practice guidelines for ventilator-associated pneumonia: diagnosis and treatment

BACKGROUND

Ventilator-associated pneumonia (VAP) is an important cause of morbidity and mortality in ventilated critically ill patients. Despite a large amount of research evidence, the optimal diagnostic and treatment strategies for VAP remain controversial.

PURPOSE

The aim of this study was to develop evidence-based clinical practice guidelines for the diagnosis and treatment of VAP. Data sources include Medline, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Database of Systematic Reviews and Register of Controlled Trials.

STUDY SELECTION

The authors systematically searched for all relevant randomized controlled trials and systematic reviews on the diagnosis and treatment of VAP in mechanically ventilated adults that were published from 1980 to October 1, 2006.

DATA EXTRACTION

Independently and in duplicate, the panel critically appraised each published trial. The effect size, confidence intervals, and homogeneity of the results were scored using predefined definitions. The full guideline development panel arrived at a consensus for scores on safety, feasibility, and economic issues.

LEVELS OF EVIDENCE

Based on the scores for each topic, the following statements of recommendation were used: recommend, consider, do not recommend, and no recommendation because of insufficient or conflicting evidence.

DATA SYNTHESIS

For the diagnosis of VAP in immunocompetent patients, we recommend that endotracheal aspirates with nonquantitative cultures be used as the initial diagnostic strategy. When there is a suspicion of VAP, we recommend empiric antimicrobial therapy (in contrast to delayed or culture directed therapy) and appropriate single agent antimicrobial therapy for each potential pathogen as empiric therapy for VAP. Choice of antibiotics should be based on patient factors and local resistance patterns. We recommend that an antibiotic discontinuation strategy be used in patients who are treated of suspected VAP. For patients who receive adequate initial antibiotic therapy, we recommend 8 days of antibiotic therapy. We do not recommend nebulized endotracheal tobramycin or intratracheal instillation of tobramycin for the treatment of VAP.

CONCLUSION

We present evidence-based recommendations for the diagnosis and treatment of VAP. Implementation of these recommendations into clinical practice may lessen the morbidity and mortality of patients who develop VAP.

Determinants of outcome in patients with a clinical suspicion of ventilator-associated pneumonia

INTRODUCTION

In the absence of a reference standard, a probabilistic approach to the diagnosis of ventilator-associated pneumonia (VAP) has been proposed; and clinician judgment augmented by microbiological tests is used to guide therapy for patients having a clinical suspicion of VAP (CSVAP). However, the correlation of both clinician judgment at the time of CSVAP and the probability of VAP with clinical outcomes is unknown. In a cohort of patients with CSVAP, we sought to determine the correlation of clinician judgment and the probability of VAP with clinical outcomes. In addition, we studied the impact of the clinical and microbiological components of CSVAP on the processes of care and outcomes.

METHODS

We performed a retrospective analysis of data from a multicenter, randomized trial in 740 patients with CSVAP. Prospective clinician judgment of VAP probability at the time of CSVAP and retrospective adjudication of VAP were compared with clinical outcomes. The following determinants of CSVAP on outcomes were studied: time of CSVAP, index culture results, and the presence of bacteremia.

RESULTS

Neither clinician index of suspicion for VAP nor retrospective adjudication of VAP correlated with clinical outcomes. For CSVAP, occurrence >7 days after start of mechanical ventilation and negative index cultures were associated with worse outcomes. Bacteremia was associated with the development of increased organ dysfunction.

CONCLUSION

In patients with CSVAP, clinician judgment as to the probability of VAP does not correlate with processes of care and outcomes; and its use to group patients into those with and without VAP is of limited clinical utility.

The value of pretest probability and modified clinical pulmonary infection score to diagnose ventilator-associated pneumonia

PURPOSE

The aim of the study was to assess the utility of pretest probability and modified clinical pulmonary infection score CPIS in the diagnosis of late-onset ventilator-associated pneumonia (VAP).

MATERIALS AND METHODS

In 740 adults enrolled in a multicenter randomized trial, intensivists prospectively rated the pretest probability of VAP as low, moderate, or high based on their clinical judgment. The modified CPIS was calculated without considering culture results. Ventilator-associated pneumonia diagnosis was determined by 2 adjudicators using standardized definitions. We analyzed the relationship between pretest likelihood, CPIS, and VAP diagnosis.

RESULTS

Among the 739 patients analyzed, 14.5%, 39.6%, and 45.9% had low, moderate, and high pretest probability of VAP. Patients with high pretest probability had a lower PaO2/FiO2 ratio and a larger volume of secretions. High or moderate vs low pretest probability had high sensitivity (0.88; 95% confidence interval [CI], 0.87-0.89) and positive predictive value (0.87; 95% CI, 0.86-0.88) but low specificity (0.27; 95% CI, 0.21-0.35) and negative predictive value (0.29; 95% C,: 0.22-0.37) for the diagnosis of VAP. Therefore, 71% of patients who had a low pretest probability were actually infected (1 - negative predictive value). The area under the receiver operating characteristic curve for the modified CPIS was not significant (0.47; 95% CI, 0.42-0.53), meaning that no score threshold was clinically useful.

CONCLUSIONS

Pretest probability and a modified CPIS, which excludes culture results, are of limited utility in the diagnosis of late-onset VAP.

Diagnosis of ventilator-associated pneumonia: a systematic review of the literature

INTRODUCTION

Early, accurate diagnosis is fundamental in the management of patients with ventilator-associated pneumonia (VAP). The aim of this qualitative review was to compare various criteria of diagnosing VAP in the intensive care unit (ICU) with a special emphasis on the value of clinical diagnosis, microbiological culture techniques, and biomarkers of host response.

METHODS

A MEDLINE search was performed using the keyword 'ventilator associated pneumonia' AND 'diagnosis'. Our search was limited to human studies published between January 1966 and June 2007. Only studies of at least 25 adult patients were included. Predefined variables were collected, including year of publication, study design (prospective/retrospective), number of patients included, and disease group.

RESULTS

Of 572 articles fulfilling the initial search criteria, 159 articles were chosen for detailed review of the full text. A total of 64 articles fulfilled the inclusion criteria and were included in our review. Clinical criteria, used in combination, may be helpful in diagnosing VAP, however, the considerable inter-observer variability and the moderate performance should be taken in account. Bacteriologic data do not increase the accuracy of diagnosis as compared to clinical diagnosis. Quantitative cultures obtained by different methods seem to be rather equivalent in diagnosing VAP. Blood cultures are relatively insensitive to diagnose pneumonia. The rapid availability of cytological data, including inflammatory cells and Gram stains, may be useful in initial therapeutic decisions in patients with suspected VAP. C-reactive protein, procalcitonin, and soluble triggering receptor expressed on myeloid cells are promising biomarkers in diagnosing VAP.

CONCLUSION

An integrated approach should be followed in diagnosing and treating patients with VAP, including early antibiotic therapy and subsequent rectification according to clinical response and results of bacteriologic cultures.

De-escalation therapy rates are significantly higher by bronchoalveolar lavage than by tracheal aspirate

Objective

To assess outcomes with de-escalation therapy in ventilator-associated pneumonia (VAP).

Design

Prospective observational study.

Setting

Multidisciplinary intensive care unit.

Patients and participants

VAP was diagnosed by positive quantitative cultures of both tracheal aspirate and bronchoalveolar lavage (BAL) and treated appropriately for all significant isolates of tracheal aspirate and BAL in 143 patients who were assigned to de-escalation therapy by BAL or tracheal aspirate.

Interventions

None.

Measurements and results

Antibiotic therapy was de-escalated in 58 patients (40.5%), who had decreased mortality at day 15 (5.1% vs. 31.7%) and day 28 (12% vs. 43.5%) and shorter intensive care unit (17.2 ± 1.2 vs. 22.7 ± 6.3 days) and hospital (23.7 ± 2.8 vs. 29.8 ± 11.1 days) stay (p < 0.05). Of the 81 patients assigned to tracheal aspirate, the 17 (21%) who achieved de-escalation of therapy had reduced 15-day mortality (5.8% vs. 34.3%), reduced 28-day mortality (11.6% vs. 45.3%), and shorter intensive care unit (17.2 ± 1.6 vs. 22.4 ± 6.4 days) and hospital (23.1 ± 4.4 vs. 29.9 ± 11.1 days) stay (p < 0.05). Of the 62 patients assigned to BAL, the 41 (66.1%) who achieved de-escalation of therapy had decreased 15-day mortality (4.8% vs. 23.8%), decreased 28-day mortality (12.1% vs. 38%), and shorter intensive care unit (17.2 ± 1.1 vs. 23.2 ± 6 days) and hospital (23.8 ± 2.4 vs. 29.8 ± 11.4 days) stay (p < 0.05).

Conclusions

For patients with VAP who have had appropriate treatment and shown a favorable clinical response, mortality and duration of stay can be further improved by de-escalation therapy.

Diagnostic strategies for nosocomial pneumonia

PURPOSE OF REVIEW

This review describes advances in clinical and microbiological modalities for diagnosis of nosocomial pneumonia and the role of biological markers.

RECENT FINDINGS

Serial assessments with the clinical pulmonary infection score identifies nonsurvivors and allows discontinuation of antibiotics when there is low suspicion of pneumonia. Studies evaluating its clinical utility show mixed results. A meta-analysis revealed that an invasive approach does not affect mortality but reduces costs, antibiotic exposure, and multidrug resistance. In contrast to these findings, a recent trial comparing nonquantitative endotracheal aspirate and quantitative bronchoalveolar lavage cultures showed similar clinical outcomes and antibiotic utilization. The role of quantitative endotracheal aspirate for diagnosis of pneumonia not related to mechanical ventilation was recently evaluated. Procalcitonin and soluble triggering receptor expressed on myeloid cells-1 aid in diagnosis, identify sepsis related to ventilator-associated pneumonia and patients with worst outcomes.

SUMMARY

The diagnostic modality chosen depends on availability, personnel experience, and the patient's clinical status. Recent guidelines support the use of quantitative cultures in an integrated clinical and microbiological algorithm. The decision to adjust antibiotics involves clinical reassessment and interpretation of culture results. Biological markers have a potential role as screening and prognostic tools.

Soluble triggering receptor expressed on myeloid cell-1 is increased in patients with ventilator-associated pneumonia: a preliminary report

RATIONALE

The diagnosis of ventilator-associated pneumonia (VAP) can be difficult. Soluble triggering receptor expressed on myeloid cell-1 (sTREM-1) has been reported to be elevated in BAL fluid from patients with VAP.

OBJECTIVES

To evaluate the utility of sTREM-1 in the diagnosis of VAP in BAL fluid and the fluid collected in the expiratory trap from the ventilator, the exhaled ventilator condensate (EVC).

METHODS

We prospectively collected BAL fluid and EVC from 23 patients clinically suspected of having VAP. A sensitive enzyme-linked immunosorbent assay was developed to measure sTREM-1. The results derived from this assay were confirmed using an immunoblot technique. The presence of VAP was clinically determined using a modified clinical pulmonary infection score of > 6.

RESULTS

VAP was diagnosed in 14 of 23 patients. sTREM-1 was detected in the EVC from 11 of 14 subjects with VAP, but from only 1 of 9 subjects without VAP, and was significantly higher in the pneumonia patients and when expressed as picograms per milliliter or picograms per microgram protein (p = 0.005, both comparisons). In contrast, sTREM-1 was detected in the BAL fluid of all 14 VAP subjects but also in 8 of 9 subjects with no pneumonia, and did not differ in the VAP subjects compared to the nonpneumonia subjects when expressed as picrograms per milliliter or picograms per microgram protein (p > 0.05 both comparisons).

CONCLUSION

sTREM-1 is detectable in EVC and may be useful in establishing or excluding the diagnosis of VAP.

Can the clinical pulmonary infection score impact ICU antibiotic days?

BACKGROUND

The Clinical Pulmonary Infection Score (CPIS) has been used in the intensive care unit (ICU) as a decision tool for initiation of antibiotics in suspected pneumonia and also for discontinuing antibiotics if the CPIS score is <or=6 on day three of therapy, but it is not in common clinical use. We sought to determine if application of a CPIS score<or=6 at three days could reduce antibiotic use and if a blinded committee would have a greater percentage of patients with CPIS>6 on day one receiving antibiotics empirically for pneumonia.

METHODS

Over 11 months, we evaluated empiric antibiotics prospectively in two ICUs of a large tertiary university teaching hospital. A pneumonia committee (PC) reviewed all patients and defined pneumonia according to the guidelines of the U.S. Centers for Disease Control and Prevention (CDC). The CPIS was calculated for all patients at day one and day three of antibiotic therapy. The percentage of patients with a CPIS<or=6 was compared for the ICU and PC, and the total antibiotic days potentially saved by using CPIS<or=6 as the criterion for treatment were determined. Receiver operating characteristic (ROC) curves and inter-observer reliability were determined.

RESULTS

Three hundred twelve patients received empiric antibiotics, 83 of whom were believed to have pneumonia by the ICU staff (2,283 antibiotic days). On day one, the 55 patients started on antibiotics had a CPIS<or=6, with 1,460 antibiotic-days, and only 28 patients had a CPIS>6 (823 antibiotic-days). In contrast, the PC determined 19 patients (23%) to have pneumonia by the CDC definition (731 antibiotic-days), with eight of these patients having a CPIS<or=6 and 11 a CPIS>6. Pneumonia committee review resulted in fewer patients believed to have pneumonia and a greater percentage with a CPIS>6 (odds ratio [OR] 2.7; 95% confidence interval [CI] 0.86, 8.6; p=0.05). Restriction of antibiotics to patients with a CPIS>6 would have saved 1,460 antibiotic-days at day one and 1,053 days if treatment was delayed until day three. Clinical Pulmonary Infection Score ROC curves for the PC showed an area under the curve (AUC) of 0.82 (95% CI 0.72, 0.91), whereas the AUC for the ICU group was 0.85 (95% CI 0.79, 0.92). The sensitivity and specificity of a CPIS>6 for the PC were 79% and 75%, respectively, with correct prediction 76% of the time. The inter-observer reliability of the CPIS had a kappa value of 0.88.

CONCLUSIONS

This prospective evaluation confirms that 50% of antibiotic-days in our ICU are used empirically for pneumonia when that infection is not likely to be present by either CDC or CPIS criteria. Although the CPIS has good reliability and acceptable sensitivity and specificity, PC review and CPIS<or=6 were commonly divergent (42-47%). Thus, better strategies should be developed for identification of pneumonia and empiric antibiotic administration in the ICU.

Agreement between quantitative cultures of postintubation tracheal aspiration and plugged telescoping catheter, protected specimen brush, or BAL for the diagnosis of nosocomial pneumonia

BACKGROUND

The diagnosis of ventilator-associated pneumonia relies on protected specimen brush (PSB), BAL, and plugged telescoping catheter (PTC) procedures. In the particular setting of nosocomial pneumonia (NP) occurring in non-mechanically ventilated patients, no consensus exists on their use. When mechanical ventilation (MV) becomes mandatory, postintubation tracheal aspiration (PITA) could be a simple, fast, and cheap diagnostic tool. Our aim was to compare the diagnostic accuracy of PITA to that of PSB, BAL, or PTC in patients requiring MV for suspected NP.

METHODS

Patients with a prior hospital stay of > or = 48 h who required MV for suspicion of NP were prospectively enrolled in the study. PITA was performed by sterile suction. Within 2 h, pulmonary samples were obtained by PSB, BAL, or blinded PTC, which are referred to hereafter as "reference methods" (RMs). The definite diagnosis of NP was made using a composite item of clinical, radiologic, and bacteriologic (ie, blood or pleural fluid cultures) patterns. The agreement between the quantitative microbiological results obtained with PITA and those of the RMs was assessed by the kappa-statistic. The sensitivity, specificity, and positive and negative likelihood ratios of PITA and RMs were calculated taking the definite diagnosis of NP as the reference.

RESULTS

There were 44 cases (63.8%) of confirmed NP. The kappa-statistic was 0.71. The sensitivity, specificity, and positive and negative likelihood ratios were 77%, 84%, 4.80, and 0.27, respectively, for PITA, and 75%, 88%, 6.25, and 0.28, respectively, for RMs.

CONCLUSIONS

PITA may be a reliable alternative to RMs in the particular setting of NP in newly mechanically ventilated patients.

Combination therapy versus monotherapy: a randomised pilot study on the evolution of inflammatory parameters after ventilator associated pneumonia [ISRCTN31976779]

Introduction

Combination antibiotic therapy for ventilator associated pneumonia (VAP) is often used to broaden the spectrum of activity of empirical treatment. The relevance of such synergy is commonly supposed but poorly supported. The aim of the present study was to compare the clinical outcome and the course of biological variables in patients treated for a VAP, using a monotherapy with a beta-lactam versus a combination therapy.

Methods

Patients with VAP were prospectively randomised to receive either cefepime alone or cefepime in association with amikacin or levofloxacin. Clinical and inflammatory parameters were measured on the day of inclusion and thereafter.

Results

Seventy-four mechanically ventilated patients meeting clinical criteria for VAP were enrolled in the study. VAP was microbiologically confirmed in 59 patients (84%). Patients were randomised to receive cefepime (C group, 20 patients), cefepime with amikacin (C-A group, 19 patients) or cefepime with levofloxacin (C-L group, 20 patients). No significant difference was observed regarding the time course of temperature, leukocytosis or C-reactive protein level. There were no differences between length of stay in the intensive care unit after infection, nor in ventilator free days within 28 days after infection. No difference in mortality was observed.

Conclusion

Antibiotic combination using a fourth generation cephalosporin with either an aminoside or a fluoroquinolone is not associated with a clinical or biological benefit when compared to cephalosporin monotherapy against common susceptible pathogens causing VAP.

Update in ventilator-associated pneumonia

PURPOSE OF REVIEW

Ventilator-associated pneumonia remains an important topic (or subject) in the care of the critically ill. Issues related to ventilator-associated pneumonia are now particularly acute given the continued increase in rates of antimicrobial resistance seen in intensive care units. This review examines the latest literature in this area, including promising approaches to infection prevention and recently developed guidelines to aid clinicians in limiting, identifying and treating ventilator-associated pneumonia.

RECENT FINDINGS

Increasingly rigorous and robust studies have shown the enormous cost, morbidity and mortality of infections acquired in the intensive care unit in general and of ventilator-associated pneumonia in particular, and offered potential management options. Specific areas of promise include advances in means of diagnosis, such as appropriate use of bronchoscopy and inflammatory markers, and treatment methods, including short-course treatment regimens and the use of 'de-escalation' as a strategy for antibiotic prescribing.

SUMMARY

Recent studies have started to illuminate the full magnitude of the impact of ventilator-associated pneumonia in the intensive care unit and suggest potential measures for intervention. Hopefully, additional work will aid in eventual development of effective preventive, diagnostic and therapeutic strategies that can reliably improve patient outcomes.

Nosocomial pneumonia: aetiology, diagnosis and treatment

PURPOSE OF REVIEW

This review highlights recent advances in the aetiology of nosocomial pneumonia, and in strategies to increase accuracy of diagnosis and antibiotic prescription while limiting unnecessary antibiotic consumption.

RECENT FINDINGS

Bacterial pathogens still cause the bulk of nosocomial pneumonia and are of concern because of ever-rising antimicrobial resistance. Yet, the pathogenic role of fungal and viral organisms is increasingly recognized. Since early appropriate antimicrobial therapy is the cornerstone of an effective treatment, further studies have been conducted to improve appropriateness of early antibiotic therapy. De-escalation strategies combine initial broad-spectrum antibiotics to maximize early antibiotic coverage with a subsequent focusing of the antibiotic spectrum when the cause is identified. Invasive techniques probably do not alter the immediate outcome but have the potential to reduce unnecessary antibiotic exposure. Decisions to stop or change antibiotic therapy are hampered due to a lack of reliable parameters to assess the resolution of pneumonia.

SUMMARY

Increasing antimicrobial resistance in nosocomial pneumonia both challenges treatment and mandates limitation of selection pressure by reducing antibiotic burden. Treating physicians should be both aggressive in initiating antimicrobials when suspecting nosocomial pneumonia but willing to discontinue antimicrobials when diagnostic results point to an alternative diagnosis. Efforts should be made to limit duration of antibiotic therapy when possible.

Diagnosis and Treatment of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in the ICU. Patients who acquire VAP have higher mortality rates and longer ICU and hospital stays. Because there are other potential causes of fever, leukocytosis, and pulmonary infiltrates, clinical diagnostic criteria are overly sensitive in the diagnosis of VAP. Employing quantitative cultures of bronchopulmonary secretions in the diagnostic algorithm leads to less antibiotic use and probably to lower mortality. With respect to microbiologic diagnosis, it is not clear that the use of a particular sampling method (bronchoscopic or nonbronchoscopic), when quantitatively cultured, is associated with better outcomes. Delayed administration of adequate antibiotic therapy is linked to an increased mortality rate. Hence, the focus of initial antibiotic therapy should be to rapidly provide antibiotic coverage for all likely pathogens and to then narrow or focus the antibiotic spectrum based on the results of quantitative cultures. Eight days of antibiotic therapy appears equivalent to 15 days of therapy except when treating nonlactose-fermenting Gram-negative organisms. In this latter situation, longer treatment durations appear to reduce the risk of recrudescence after discontinuation of antibiotic therapy. A guideline-based approach using the local hospital or ICU antibiogram can increase the likelihood that adequate initial antibiotic therapy is used and reduce the overall use of antibiotics and the associated selection pressure for multidrug-resistant organisms.

Tracheobronchial aspiration of gastric contents in critically ill tube-fed patients: frequency, outcomes, and risk factors

OBJECTIVES

To describe the frequency of pepsin-positive tracheal secretions (a proxy for the aspiration of gastric contents), outcomes associated with aspiration (including a positive Clinical Pulmonary Infection Score [a proxy for pneumonia] and use of hospital resources), and risk factors associated with aspiration and pneumonia in a population of critically ill tube-fed patients.

DESIGN

Prospective descriptive study conducted over a 2-yr period.

SETTING

Five intensive care units in a university-affiliated medical center with level I trauma status.

PATIENTS

Each of the 360 adult patients participated for 4 days. Among the inclusion criteria were mechanical ventilation and tube feedings. An exclusion criterion was physician-diagnosed pneumonia at the time of enrollment.

INTERVENTION

None. MEASUREMENTS AND MAJOR RESULTS: Almost 6,000 tracheal secretions collected during routine suctioning were assayed for pepsin; of these, 31.3% were positive. At least one aspiration event was identified in 88.9% (n = 320) of the participants. The incidence of pneumonia (as determined by the Clinical Pulmonary Infection Score) increased from 24% on day 1 to 48% on day 4. Patients with pneumonia on day 4 had a significantly higher percentage of pepsin-positive tracheal secretions than did those without pneumonia (42.2% vs. 21.1%, respectively; p < .001). Length of stay in the intensive care unit and need for ventilator support were significantly greater for patients with pneumonia (p < .01). A low backrest elevation was a risk factor for aspiration (p = .024) and pneumonia (p = .018). Other risk factors for aspiration included vomiting (p = .007), gastric feedings (p = .009), a Glasgow Coma Scale score <9 (p = .021), and gastroesophageal reflux disease (p = .033). The most significant independent risk factors for pneumonia were aspiration (p < .001), use of paralytic agents (p = .002), and a high sedation level (p = .039).

CONCLUSIONS

Aspiration of gastric contents is common in critically ill tube-fed patients and is a major risk factor for pneumonia. Furthermore, it leads to greater use of hospital resources. Modifiable risk factors for aspiration need to be addressed.

The futility of the clinical pulmonary infection score in trauma patients

INTRODUCTION

The Clinical Pulmonary Infection Score (CPIS) has received much attention recently. Advocates have touted its use for the diagnosis and duration of therapy in patients with ventilator-associated pneumonia (VAP). However, little has been written about its utility in trauma patients. The clinical, physiologic, and radiologic components of the CPIS may be difficult to differentiate from the systemic effects of injury. Quantitative cultures of the lower airway have been shown to be efficacious in differentiating VAP from the systemic inflammatory response syndrome (SIRS). In this study, we evaluated the potential use of CPIS as the sole means for diagnosis of VAP in critically injured patients.

METHODS

Patients were identified from the VAP database maintained in our Level I trauma center. Only those who had CPIS calculated at the time of bronchoscopy with BAL were included. VAP required >or=10 colonies/mL on quantitative BAL for diagnosis. Antibiotic therapy was based on quantitative BAL results. Patients with <10 colonies/mL were diagnosed with SIRS. Sensitivity and specificity of a CPIS>6 for VAP diagnosis (confirmed by BAL) were calculated.

RESULTS

In all, 158 patients underwent 285 BALs. The overall incidence for VAP was 42%. Patients with episodes of VAP and SIRS were well matched for age, Injury Severity Score, APACHE II score, and Glasgow Coma Scale score. The average CPIS was 6.8 in patients with SIRS and 6.9 for those with VAP. Using a CPIS>6 as the threshold for VAP only yielded a sensitivity of 61% and a specificity of 43%.

CONCLUSIONS

CPIS cannot differentiate VAP from SIRS in critically injured patients. Using CPIS to initiate antibiotic therapy in trauma patients could be harmful. Whether CPIS is useful to determine duration of antibiotic therapy is unknown.

Use of computerized surveillance to detect nosocomial pneumonia in neonatal intensive care unit patients

BACKGROUND

Pneumonia surveillance is difficult and time-consuming. The definition is complicated, and there are many opportunities for subjectivity in determining infection status.

OBJECTIVE

To compare traditional infection control professional (ICP) surveillance for pneumonia among neonatal intensive care unit (NICU) patients with computerized surveillance of chest x-ray reports using an automated detection system based on a natural language processor.

METHODS

This system evaluated chest x-rays from 2 NICUs over a 2-year period. It flagged x-rays indicative of pneumonia according to rules derived from the National Nosocomial Infection Surveillance System definition as applied to radiology reports. Data from the automated system were compared with pneumonia data collected prospectively by an ICP.

RESULTS

Sensitivity of the computerized surveillance in NICU 1 was 71%, and specificity was 99.8%. The positive predictive value was 7.9%, and the negative predictive value (NPV) was >99%. Data from NICU 2 were incomplete.

CONCLUSIONS

Computer-assisted surveillance has the potential to decrease ICP workload and make pneumonia surveillance feasible. The high NPV means the system can safely screen out many chest x-rays of noninfected patients. However, all data must be available to the computer system and must be analyzed the same way for results to be comparable.

Effect of Backrest Elevation on the Development of Ventilator-Associated Pneumonia

• Background Ventilator-associated pneumonia is a common complication of mechanical ventilation. Backrest position and time spent supine are critical risk factors for aspiration, increasing the risk for pneumonia. Empirical evidence of the effect of backrest positions on the incidence of ventilator-associated pneumonia, especially during mechanical ventilation over time, is limited.

• Objective To describe the relationship between backrest elevation and development of ventilator-associated pneumonia.

• Methods A nonexperimental, longitudinal, descriptive design was used. The Clinical Pulmonary Infection Score was used to determine ventilator-associated pneumonia. Backrest elevation was measured continuously with a transducer system. Data were obtained from laboratory results and medical records from the start of mechanical ventilation up to 7 days.

• Results Sixty-six subjects were monitored (276 patient days). Mean backrest elevation for the entire study period was 21.7°. Backrest elevations were less than 30° 72% of the time and less than 10° 39% of the time. The mean Clinical Pulmonary Infection Score increased but not significantly, and backrest elevation had no direct effect on mean scores. A model for predicting the Clinical Pulmonary Infection Score at day 4 included baseline score, percentage of time spent at less than 30° on study day 1, and score on the Acute Physiology and Chronic Health Evaluation II, explaining 81% of the variability (F=7.31, P=.003).

• Conclusions Subjects spent the majority of the time at backrest elevations less than 30°. Only the combination of early, low backrest elevation and severity of illness affected the incidence of ventilator-associated pneumonia.

Recent Trends in the Management of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) occurs frequently in mechanically ventilated patients and has a high mortality rate. To date, there is no consensus for the diagnosis of VAP. Effective reduction in VAP-inducedmortality requires amultifaceted approach to include assessment of individual risks for VAP, implementation of effective ventilator handling procedures, routine use of VAP prevention strategies, appropriate use and interpretation of invasive and noninvasive diagnostic tests, and early broad spectrum antibiotic coverage with narrowing of coverage and cessation of therapy based on clinical improvement. Pharmacokinetic and pharmacodynamic principlesmust be used in designingempiric antibiotic regimens. Because an inappropriate empiric regimen in VAP has been associated with increasedmortality, it is imperative to maintain intensive care unit–specific epidemiologic data.

The treatment of ventilator-associated pneumonia

OBJECTIVE

This manuscript attempts to provide insight into current concepts of prevention, diagnosis, and management of ventilator-associated pneumonia (VAP).

DATA SOURCES

A Medline search from 1996 to May 2004 was performed. Search terms included: ventilator-associated pneumonia with prevention, diagnosis, management, duration, resistance, and outcome.

DATA SELECTION

Emphasis was placed on the recent peer-reviewed literature. Human data were preferentially included.

DATA EXTRACTION

Where possible, recent publications (within the last year) were used in preference to older data. The references were chosen to present key citations.

DATA SYNTHESIS

Data selection was prioritized to address specific subtopics.

CONCLUSIONS

The treatment and prevention of VAP is evolving rapidly based on improved diagnostic skills and a better understanding of optimal antimicrobial therapy. An overview of new and key data guiding clinicians in the management of this important disease is presented.

Prevention of infection in the intensive care unit

PURPOSE OF REVIEW

Infections remain an important threat for critically ill patients, and the emergence of antibiotic resistance is increasingly hampering successful treatment. In this review, new aspects of the diagnosis and prevention of ventilator-associated pneumonia and of strategies of antibiotic use to limit the development and spread of resistance are described.

RECENT FINDINGS

Prevention of ventilator-associated pneumonia is cost effective, but the most optimal preventive measure (or set of measures) remains controversial. There is growing evidence that antibiotic prophylaxis reduces the occurrence of ventilator-associated pneumonia and improves patient outcome. Moreover, antibiotic use can be reduced by increasing the specificity of diagnosing ventilator-associated pneumonia and by limiting the duration of antibiotic treatment.

SUMMARY

Recent developments in diagnosis, treatment, and prevention of ventilator-associated pneumonia and strategies to reduce emergence of antibiotic resistance have been reviewed. Whether changes in antibiotic policy will reduce the emergence of antibiotic resistance remains to be determined. In this area, methodologic problems that have been overlooked in many studies have been addressed recently. These issues must be clarified to provide reliable data on the effects of interventions in hospital settings.

Value of the clinical pulmonary infection score for the identification and management of ventilator-associated pneumonia

OBJECTIVE

To evaluate the potential ability of an algorithm based on the clinical pulmonary infection score (CPIS) to identify and treat patients with bacterial ventilator-associated pneumonia (VAP) compared to a strategy based on quantitative cultures of bronchoscopic specimens.

DESIGN

Retrospective cohort study.

SETTING

Thirty-one critical care units across France.

PATIENTS

Two hundred and one patients clinically suspected of having VAP who had been included in the "invasive strategy" group of the French multicenter randomized trial and for whose quantitative cultures bronchoscopic specimens were obtained. CPIS was determined retrospectively, based on data that had been collected for the initial study.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The clinical pulmonary infection score was determined on days 1 and 3, and compared in patients identified as having developed VAP or not, as defined by bronchoscopic specimen culture results. On day 3 138 of the 201 patients (69%) had a CPIS of more than 6 that would have required prolonged antimicrobial therapy based on the algorithm. In contrast, based on bronchoscopy, only 88 (44%) patients were considered to have VAP (kappa coefficient for concordance between the two strategies, 0.33). While the sensitivity of CPIS more than 6 on day 3 for identifying VAP was 89%, its specificity was only 47%, leading to potentially unnecessary treatment of 60 (53%) of the 113 patients without VAP as diagnosed by bronchoscopy.

CONCLUSION

A strategy based on the CPIS to decide which patients with suspected VAP should receive prolonged administration of antibiotics would appear to over-prescribe these agents, as compared to a strategy based on bronchoscopy.