0
Original Research: Critical Care |

Impact of Diagnostic Criteria on the Incidence of Ventilator-Associated PneumoniaVentilator-Associated Pneumonia Criteria FREE TO VIEW

Amédée Ego, MD; Jean-Charles Preiser, MD, PhD; Jean-Louis Vincent, MD, PhD, FCCP
Author and Funding Information

From the Department of Intensive Care, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium.

CORRESPONDENCE TO: Jean-Louis Vincent, MD, PhD, FCCP, Department of Intensive Care, Erasme University Hospital, Route de Lennik 808, B-1070 Brussels, Belgium; e-mail: jlvincen@ulb.ac.be


The results of this study were presented in part at the 26th Annual Congress of the European Society of Intensive Care Medicine, October 5-9, 2013, Paris, France.

FUNDING/SUPPORT: The authors have reported to CHEST that no funding was received for this study.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;147(2):347-355. doi:10.1378/chest.14-0610
Text Size: A A A
Published online

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.

Figures in this Article

Ventilator-associated pneumonia (VAP) is a common complication in patients in the ICU and is associated with increased mortality,1,2 prolonged duration of mechanical ventilation (MV) and length of stay, and increased costs.3,4 Institutions are encouraged to use preventive measures, including careful hand washing, oral care, and decontamination; high-volume low-pressure balloon cuffs; elevation of the head of the patient’s bed; early feeding; avoidance of sedative agents; and early weaning from MV.5

The reported incidence of VAP varies considerably among studies, ranging from 5% to 67%.1,3,6 A survey of US trauma centers showed that the incidence of VAP was markedly higher than those reported by the National Healthcare Safety Network and varied considerably among centers.7 However, the criteria used to diagnose VAP also vary widely, as shown by the large number of published diagnostic algorithms, and this may impact the reported incidence of VAP.811 It is, therefore, difficult to compare the incidence of VAP among hospitals. Even with strict criteria, the interpretation of some factors, such as the radiographs or the aspect of tracheal secretions, can be very subjective.

Therefore, we evaluated how the use of different criteria may lead to different apparent incidences of VAP. This effect may have important implications for clinical trials, hospital management, and quality control.

This study was conducted in the Erasme University Hospital, 35-bed, medical-surgical ICU, which admits 3,000 to 3,500 patients per year. The nurse-to-bed ratio varies between 2:4 and 2:6, and respiratory physiotherapists are on-site 24/7. The study was approved by the institution’s Ethics Committee (reference P2013/076), which waived the need for informed consent in view of the purely observational nature of the study.

We prospectively screened all adult patients (> 18 years old) treated with invasive MV for more than 48 h between January 1, 2012, and July 31, 2012. Patients with a diagnosis of respiratory tract infection and/or pneumonia on admission or within the first 48 h of MV were not included. We collected epidemiologic data on admission. During invasive MV, we collected respiratory data (mode of MV, positive end-expiratory pressure [PEEP], Pao2, Fio2), WBC count including differential, C-reactive protein (CRP) level, temperature, the degree of purulence of tracheal secretions and microbiology data from tracheal aspirates or BAL, when performed. Chest radiography was conducted on a daily basis. We recorded durations of MV, lengths of ICU and hospital stays, and ICU and hospital mortality rates.

We applied six sets of published criteria: US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia (CDC/NHSN PNU1) 2008,12 the Clinical Pulmonary Infection Score (CPIS),13 Johanson’s criteria,14 American College of Chest Physicians (CHEST),15 Hospital in Europe Link for Infection Control through Surveillance (HELICS),16 and the new definition (probable VAP) from US Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN)17 (Table 1). We also combined criteria for oxygenation, host response, purulence of tracheal aspirates, and chest radiography and microbiologic findings that have been used in previous diagnostic algorithms (Fig 1, Table 2) to create 89 sets, varying in number of criteria (two to five) and in the thresholds required.

Figure Jump LinkFigure 1 –  Construction of the 89 sets of criteria. See also e-Table 1. CRP = C-reactive protein; ETA = endotracheal aspirate.Grahic Jump Location
Table Graphic Jump Location
TABLE 1 ]  The Diagnostic Requirements for the Six Published Sets of Criteria

CDC/NHSN = US Centers for Disease Control and Prevention/National Healthcare Safety Network; CDC/NHSN PNU1 = US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia; CHEST = American College of Chest Physicians; CPIS = Clinical Pulmonary Infection Score; HELICS = Hospital in Europe Link for Infection Control through Surveillance; lpf = low-power field; PEEP = positive-end expiratory pressure; RSV = respiratory syncytial virus; VAP = ventilator-associated pneumonia.

Table Graphic Jump Location
TABLE 2 ]  Criteria Used to Build the 89 Sets

CRP = C-reactive protein; ETA = endotracheal aspirate. See Table 1 legend for expansion of other abbreviation.

a 

Bartlett classification.18

We selected the worst values of the day for each variable, except for the application of the new definition from CDC/NHSN,17 which requires the minimum daily Fio2 or PEEP. All the variables used for the different diagnostic algorithms were assessed daily during MV.

Statistical Analysis

Normality of distribution was checked by the Shapiro-Wilk test. Variables that were not normally distributed are expressed as median (with 25th-75th percentiles). We used Cohen κ to evaluate the agreement between algorithms. All statistical analyses were performed using IBM SPSS 21.0 (IBM). A P value < .05 was considered statistically significant.

Among the 1,824 admissions between January 1 and July 31, 2012, 144 patients required invasive MV for more than 48 h. Of these patients, 53 had a diagnosis of respiratory infection on admission or within the first 48 h of MV, and 91 patients were eligible for analysis (Fig 2). The characteristics of these patients are shown in Table 3: The population was severely ill, as indicated by a median APACHE (Acute Physiology and Chronic Health Evaluation) II score of 25.

Figure Jump LinkFigure 2 –  Population flowchart. MV = mechanical ventilation.Grahic Jump Location
Table Graphic Jump Location
TABLE 3 ]  Population Characteristics

Data given as No. (%) unless otherwise indicated.

APACHE = Acute Physiology and Chronic Health Evaluation; ECMO = extracorporeal membrane oxygenation; IQR = interquartile range; VA = venoarterial; VV = venovenous.

Using the published criteria, the incidence of VAP ranged from 4% with Johanson’s criteria to 42% with the CPIS (Fig 3), with poor agreement between the scores (Table 4). Using the 89 combined sets of criteria, the incidence of VAP decreased from 44% to 0% when applying combinations of increasing stringency (Fig 4, e-Table 1). The least stringent set of criteria included just two factors of low level severity (increase in Fio2 by at least 0.15 or in PEEP values by at least 2 cm H2O, and increase in CRP values by at least 50 mg/L from one day to the next), whereas the most stringent set included five criteria with much higher levels of severity required (increase in Fio2 values by at least 0.30 or in PEEP values by at least 5 cm H2O for at least two calendar days; increase in CRP value by at least 50 mg/L or temperature at 38°C or above; purulent tracheal secretions; positive microbiology; and new or progressive and persistent infiltrate/consolidation on chest radiography). Mortality was greatest in patients in whom VAP was diagnosed using the most stringent set of criteria (Fig 4A). The diagnosis of VAP took longer to establish when applying more stringent compared with less stringent criteria (Fig 4B). There was a slight increase in the duration of MV in patients in whom VAP was diagnosed using the most stringent sets of criteria compared with less stringent sets (Fig 4C).

Figure Jump LinkFigure 3 –  Incidence of VAP according to the published algorithms. CDC/NHSN PNU1 = US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia; ACCP = American College of Chest Physicians; CPIS = Clinical Pulmonary Infection Score; HELICS = Hospital in Europe Link for Infection Control through Surveillance; VAP = ventilator-associated pneumonia.Grahic Jump Location
Table Graphic Jump Location
TABLE 4 ]  Agreement Between Published Criteriaa

See Table 1 legend for expansion of abbreviations.

a 

Assessed using Cohen κ (0-0.20: very low agreement; 0.21-0.40: low; 0.41-0.60: moderate; 0.61-0.80: strong; 0.81-1: almost perfect).

Figure Jump LinkFigure 4 –  A, Incidence of VAP according to the 89 sets of criteria used and hospital mortality. B, Delay before the diagnosis of VAP according to the incidence of VAP. C, Duration of MV according to the incidence of VAP. IQR = interquartile range. See Figure 2 and 3 legends for expansion of other abbreviations.Grahic Jump Location

The aim of the present study was to demonstrate that the incidence of VAP can vary widely according to the criteria chosen to diagnose it, and we, therefore, deliberately chose not to define our rate of VAP. Indeed, the estimated incidence of VAP varied from 4% to 42% depending on which of the six published diagnostic algorithms was used. We also illustrated that, by selecting specific, stringent criteria, we could manipulate the incidence of VAP to zero. As expected, stringent and thus more specific sets of criteria selected patients with higher mortality rates than did less stringent sets.

Our results are consistent with previous studies on this issue. Minei et al8 showed that the incidences of VAP using the CDC/NHSN PNU1 criteria, Johanson’s criteria, and clinician’s opinion were 48%, 4%, and 17%, respectively. Skrupky et al9 showed poor agreement between the CDC/NHSN PNU1 criteria and the CHEST criteria (κ = 0.26). Tejerina et al10 compared eight sets of criteria and showed a decrease in the incidence of VAP and improved specificity by applying more rigorous sets of criteria. Similarly, Klompas et al11 showed a lower incidence of VAP when using the more stringent of 32 sets of criteria.

Our study confirms these observations but with the added advantage of using a very large number of criteria with a larger range of stringent combinations, thus enabling us to achieve a virtual zero VAP rate. The relevance of surveillance of VAP as a marker of quality of care can thus be questioned, because the subjectivity and inconsistencies of the criteria used to diagnose VAP make it possible to manipulate its true incidence. Even studies using microbiologic criteria to diagnose VAP have shown differences in diagnostic rates depending on which technique is used to collect the sample.19,20 Thus, studies on VAP surveillance should also be interpreted with caution.

The strengths of our study include the prospective inclusion of consecutive patients, and so it was representative of the entire patient population admitted to a large multidisciplinary ICU during the study period. The population studied was severely ill, with a median APACHE score of 25 and a 50% hospital mortality rate. We did not attempt to evaluate the quality of care in our institution, as this was not the purpose of the study.

The single-center nature of our study could be seen as a weakness but also a strength, as it limits the variability in care that can occur across different centers. The number of patients was relatively limited, but sufficient to demonstrate clear differences in incidence rates and outcomes with different criteria. We may have underestimated slightly the incidence of VAP according to the US Centers for Disease Control and Prevention definition,12 which allows for diagnosis of VAP for up to 48 h after extubation, but this would not have impacted our main findings. The impossibility of obtaining a definitive diagnosis based on pathologic evaluation is an obvious limitation of all studies on this topic.

These observations challenge the use of VAP as a marker of quality of care, at least if the criteria used are left to the individual’s choice. Even if the criteria are well defined, there may still be interobserver variability, but we did not specifically study this phenomenon.

In conclusion, the diagnosis of VAP is highly variable depending on the criteria selected to identify it. VAP may even “disappear” totally if stringent criteria are used.

Author contributions: A. E. is the guarantor of the manuscript and takes responsibility for the integrity of the data and the accuracy of the data analysis. A. E. drafted the manuscript, collected data, and served as principal author; A. E. and J.-C. P. contributed to data analysis; J.-C. P. and J.-L. V. contributed to revising the manuscript; and A. E., J.-C. P., and J.-L. V. contributed to the study design and all approved the final version of the manuscript.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Additional information: The e-Table can be found in the Supplemental Materials section of the online article.

APACHE

Acute Physiology and Chronic Health Evaluation

CDC/NHSN

US Centers for Disease Control and Prevention/National Healthcare Safety Network

CDC/NHSN PNU1

US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia

CHEST

American College of Chest Physicians

CPIS

Clinical Pulmonary Infection Score

CRP

C-reactive protein

HELICS

Hospital in Europe Link for Infection Control through Surveillance

MV

mechanical ventilation

PEEP

positive-end expiratory pressure

VAP

ventilator-associated pneumonia

Chastre J, Fagon J-Y. Ventilator-associated pneumonia. Am J Respir Crit Care Med. 2002;165(7):867-903. [CrossRef] [PubMed]
 
Fagon JY, Chastre J, Vuagnat A, Trouillet JL, Novara A, Gibert C. Nosocomial pneumonia and mortality among patients in intensive care units. JAMA. 1996;275(11):866-869. [CrossRef] [PubMed]
 
Safdar N, Dezfulian C, Collard HR, Saint S. Clinical and economic consequences of ventilator-associated pneumonia: a systematic review. Crit Care Med. 2005;33(10):2184-2193. [CrossRef] [PubMed]
 
Kollef MH, Hamilton CW, Ernst FR. Economic impact of ventilator-associated pneumonia in a large matched cohort. Infect Control Hosp Epidemiol. 2012;33(3):250-256. [CrossRef] [PubMed]
 
Coffin SE, Klompas M, Classen D, et al. Strategies to prevent ventilator-associated pneumonia in acute care hospitals. Infect Control Hosp Epidemiol. 2008;29(suppl 1):S31-S40. [CrossRef] [PubMed]
 
Suetens C, Morales I, Savey A, et al. European surveillance of ICU-acquired infections (HELICS-ICU): methods and main results. J Hosp Infect. 2007;65(suppl 2):171-173. [CrossRef] [PubMed]
 
Michetti CP, Fakhry SM, Ferguson PL, Cook A, Moore FO, Gross R; AAST Ventilator-Associated Pneumonia Investigators. Ventilator-associated pneumonia rates at major trauma centers compared with a national benchmark: a multi-institutional study of the AAST. J Trauma Acute Care Surg. 2012;72(5):1165-1173. [PubMed]
 
Minei JP, Hawkins K, Moody B, et al. Alternative case definitions of ventilator-associated pneumonia identify different patients in a surgical intensive care unit. Shock. 2000;14(3):331-336. [CrossRef] [PubMed]
 
Skrupky LP, McConnell K, Dallas J, Kollef MH. A comparison of ventilator-associated pneumonia rates as identified according to the National Healthcare Safety Network and American College of Chest Physicians criteria. Crit Care Med. 2012;40(1):281-284. [CrossRef] [PubMed]
 
Tejerina E, Esteban A, Fernández-Segoviano P, et al. Accuracy of clinical definitions of ventilator-associated pneumonia: comparison with autopsy findings. J Crit Care. 2010;25(1):62-68. [CrossRef] [PubMed]
 
Klompas M, Magill S, Robicsek A, et al; CDC Prevention Epicenters Program. Objective surveillance definitions for ventilator-associated pneumonia. Crit Care Med. 2012;40(12):3154-3161. [CrossRef] [PubMed]
 
Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of health care-associated infection and criteria for specific types of infections in the acute care setting. Am J Infect Control. 2008;36(5):309-332. [CrossRef] [PubMed]
 
Croce MA, Swanson JM, Magnotti LJ, et al. The futility of the clinical pulmonary infection score in trauma patients. J Trauma. 2006;60(3):523-527. [CrossRef] [PubMed]
 
Johanson WG Jr, Pierce AK, Sanford JP, Thomas GD. Nosocomial respiratory infections with gram-negative bacilli. The significance of colonization of the respiratory tract. Ann Intern Med. 1972;77(5):701-706. [CrossRef] [PubMed]
 
Grossman RF, Fein A. Evidence-based assessment of diagnostic tests for ventilator-associated pneumonia. Executive summary. Chest. 2000;117(4_suppl_2):177S-181S. [CrossRef] [PubMed]
 
Hospital in Europe Link for Infection Control through Surveillance. Surveillance of Nosocomial Infections in Intensive Care Units. Protocol, Version 6.1. Brussels, Belgium: Scientific Institute of Public Health; 2004.
 
The National Healthcare Safety Network (NHSN). Device-associated module: ventilator-associated event. US Centers for Disease Control and Prevention website. http://www.cdc.gov/nhsn/PDFs/pscManual/10-VAE_FINAL.pdf. Accessed October 22, 2014.
 
Bartlett JG. Diagnostic tests for agents of community-acquired pneumonia. Clin Infect Dis. 2011;52(suppl 4):S296-S304. [CrossRef] [PubMed]
 
Mondi MM, Chang MC, Bowton DL, Kilgo PD, Meredith JW, Miller PR. Prospective comparison of bronchoalveolar lavage and quantitative deep tracheal aspirate in the diagnosis of ventilator associated pneumonia. J Trauma. 2005;59(4):891-895. [CrossRef] [PubMed]
 
Morris AC, Kefala K, Simpson AJ, et al. Evaluation of the effect of diagnostic methodology on the reported incidence of ventilator-associated pneumonia. Thorax. 2009;64(6):516-522. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1 –  Construction of the 89 sets of criteria. See also e-Table 1. CRP = C-reactive protein; ETA = endotracheal aspirate.Grahic Jump Location
Figure Jump LinkFigure 2 –  Population flowchart. MV = mechanical ventilation.Grahic Jump Location
Figure Jump LinkFigure 3 –  Incidence of VAP according to the published algorithms. CDC/NHSN PNU1 = US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia; ACCP = American College of Chest Physicians; CPIS = Clinical Pulmonary Infection Score; HELICS = Hospital in Europe Link for Infection Control through Surveillance; VAP = ventilator-associated pneumonia.Grahic Jump Location
Figure Jump LinkFigure 4 –  A, Incidence of VAP according to the 89 sets of criteria used and hospital mortality. B, Delay before the diagnosis of VAP according to the incidence of VAP. C, Duration of MV according to the incidence of VAP. IQR = interquartile range. See Figure 2 and 3 legends for expansion of other abbreviations.Grahic Jump Location

Tables

Table Graphic Jump Location
TABLE 1 ]  The Diagnostic Requirements for the Six Published Sets of Criteria

CDC/NHSN = US Centers for Disease Control and Prevention/National Healthcare Safety Network; CDC/NHSN PNU1 = US Centers for Disease Control and Prevention/National Healthcare Safety Network clinically defined pneumonia; CHEST = American College of Chest Physicians; CPIS = Clinical Pulmonary Infection Score; HELICS = Hospital in Europe Link for Infection Control through Surveillance; lpf = low-power field; PEEP = positive-end expiratory pressure; RSV = respiratory syncytial virus; VAP = ventilator-associated pneumonia.

Table Graphic Jump Location
TABLE 2 ]  Criteria Used to Build the 89 Sets

CRP = C-reactive protein; ETA = endotracheal aspirate. See Table 1 legend for expansion of other abbreviation.

a 

Bartlett classification.18

Table Graphic Jump Location
TABLE 3 ]  Population Characteristics

Data given as No. (%) unless otherwise indicated.

APACHE = Acute Physiology and Chronic Health Evaluation; ECMO = extracorporeal membrane oxygenation; IQR = interquartile range; VA = venoarterial; VV = venovenous.

Table Graphic Jump Location
TABLE 4 ]  Agreement Between Published Criteriaa

See Table 1 legend for expansion of abbreviations.

a 

Assessed using Cohen κ (0-0.20: very low agreement; 0.21-0.40: low; 0.41-0.60: moderate; 0.61-0.80: strong; 0.81-1: almost perfect).

References

Chastre J, Fagon J-Y. Ventilator-associated pneumonia. Am J Respir Crit Care Med. 2002;165(7):867-903. [CrossRef] [PubMed]
 
Fagon JY, Chastre J, Vuagnat A, Trouillet JL, Novara A, Gibert C. Nosocomial pneumonia and mortality among patients in intensive care units. JAMA. 1996;275(11):866-869. [CrossRef] [PubMed]
 
Safdar N, Dezfulian C, Collard HR, Saint S. Clinical and economic consequences of ventilator-associated pneumonia: a systematic review. Crit Care Med. 2005;33(10):2184-2193. [CrossRef] [PubMed]
 
Kollef MH, Hamilton CW, Ernst FR. Economic impact of ventilator-associated pneumonia in a large matched cohort. Infect Control Hosp Epidemiol. 2012;33(3):250-256. [CrossRef] [PubMed]
 
Coffin SE, Klompas M, Classen D, et al. Strategies to prevent ventilator-associated pneumonia in acute care hospitals. Infect Control Hosp Epidemiol. 2008;29(suppl 1):S31-S40. [CrossRef] [PubMed]
 
Suetens C, Morales I, Savey A, et al. European surveillance of ICU-acquired infections (HELICS-ICU): methods and main results. J Hosp Infect. 2007;65(suppl 2):171-173. [CrossRef] [PubMed]
 
Michetti CP, Fakhry SM, Ferguson PL, Cook A, Moore FO, Gross R; AAST Ventilator-Associated Pneumonia Investigators. Ventilator-associated pneumonia rates at major trauma centers compared with a national benchmark: a multi-institutional study of the AAST. J Trauma Acute Care Surg. 2012;72(5):1165-1173. [PubMed]
 
Minei JP, Hawkins K, Moody B, et al. Alternative case definitions of ventilator-associated pneumonia identify different patients in a surgical intensive care unit. Shock. 2000;14(3):331-336. [CrossRef] [PubMed]
 
Skrupky LP, McConnell K, Dallas J, Kollef MH. A comparison of ventilator-associated pneumonia rates as identified according to the National Healthcare Safety Network and American College of Chest Physicians criteria. Crit Care Med. 2012;40(1):281-284. [CrossRef] [PubMed]
 
Tejerina E, Esteban A, Fernández-Segoviano P, et al. Accuracy of clinical definitions of ventilator-associated pneumonia: comparison with autopsy findings. J Crit Care. 2010;25(1):62-68. [CrossRef] [PubMed]
 
Klompas M, Magill S, Robicsek A, et al; CDC Prevention Epicenters Program. Objective surveillance definitions for ventilator-associated pneumonia. Crit Care Med. 2012;40(12):3154-3161. [CrossRef] [PubMed]
 
Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of health care-associated infection and criteria for specific types of infections in the acute care setting. Am J Infect Control. 2008;36(5):309-332. [CrossRef] [PubMed]
 
Croce MA, Swanson JM, Magnotti LJ, et al. The futility of the clinical pulmonary infection score in trauma patients. J Trauma. 2006;60(3):523-527. [CrossRef] [PubMed]
 
Johanson WG Jr, Pierce AK, Sanford JP, Thomas GD. Nosocomial respiratory infections with gram-negative bacilli. The significance of colonization of the respiratory tract. Ann Intern Med. 1972;77(5):701-706. [CrossRef] [PubMed]
 
Grossman RF, Fein A. Evidence-based assessment of diagnostic tests for ventilator-associated pneumonia. Executive summary. Chest. 2000;117(4_suppl_2):177S-181S. [CrossRef] [PubMed]
 
Hospital in Europe Link for Infection Control through Surveillance. Surveillance of Nosocomial Infections in Intensive Care Units. Protocol, Version 6.1. Brussels, Belgium: Scientific Institute of Public Health; 2004.
 
The National Healthcare Safety Network (NHSN). Device-associated module: ventilator-associated event. US Centers for Disease Control and Prevention website. http://www.cdc.gov/nhsn/PDFs/pscManual/10-VAE_FINAL.pdf. Accessed October 22, 2014.
 
Bartlett JG. Diagnostic tests for agents of community-acquired pneumonia. Clin Infect Dis. 2011;52(suppl 4):S296-S304. [CrossRef] [PubMed]
 
Mondi MM, Chang MC, Bowton DL, Kilgo PD, Meredith JW, Miller PR. Prospective comparison of bronchoalveolar lavage and quantitative deep tracheal aspirate in the diagnosis of ventilator associated pneumonia. J Trauma. 2005;59(4):891-895. [CrossRef] [PubMed]
 
Morris AC, Kefala K, Simpson AJ, et al. Evaluation of the effect of diagnostic methodology on the reported incidence of ventilator-associated pneumonia. Thorax. 2009;64(6):516-522. [CrossRef] [PubMed]
 
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Supporting Data

Online Supplement

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543