Main Menu Browse by Day or Program Author Keywords

382 Exploration and Validation of Potential Objective Definitions for Ventilator-Associated Pneumonia

Sunday, April 3, 2011: 10:30 AM
Coronado A (Hilton Anatole)
Michael Klompas, MD, MPH , Harvard Medical School and Havard Pilgrim Health Care Institute, Boston, MA
Shelley Magill, MD, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Ari Robicsek, MD , NorthShore University HealthSystem, Evanston, IL
Ken Kleinman, PhD , Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA
R. Scott Evans, Ms, PhD, FACMI , Intermountain Healthcare / University of Utah, Salt Lake City, UT
James F. Lloyd, BS , University of Utah, Salt Lake City, UT
Deborah S. Yokoe, MD, MPH , Brigham and Women's Hospital and Harvard Medical School, Boston, MA
Yosef Khan, MBBS, MPH , The Ohio State University Medical Center, Columbus, OH
Kurt Stevenson , The Ohio State University Medical Center, Columbus, OH
Matthew Samore, MD , VA Salt Lake City IDEAS Center, Salt Lake City, UT
Richard Platt, MD, MS , Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA
Background: The current NHSN definition for ventilator-associated pneumonia is complex, laborious, subjective, and inconsistently predicts outcomes.  A new definition based on objective criteria and clearly associated with poor outcomes is needed to make interfacility comparisons more credible. 

Objective: Assess incidence-density and attributable length-of-stay and mortality for alternative VAP definitions based on objective criteria.   

Methods: Electronically collectible clinical data from consecutively ventilated patients were gathered from four teaching and two community hospitals, with a minimum of at least six months of data per hospital. Variables included daily minimum ventilator PEEP and FiO2 settings, temperatures, white blood cell counts, gram stain analyses of pulmonary secretions, and culture results. We assessed the additive value of different inflammatory signs alone and in combination in patients with evidence of worsening gas exchange (defined as a rise in PEEP by 2cm H2O or increase in FiO2 by 15 points sustained for ≥2 calendar days after ≥2 days of stable or decreasing PEEP or FiO2).  For each potential VAP definition, we calculated prevalence, incidence-density, excess ventilator and hospital days, and hospital mortality for patients with VAP compared to controls matched for hospital, age, Charlson score, and time prior to VAP onset.

Results: Data were collated on 7,379 episodes of ventilation spanning 37,120 ventilator-days. Four sample definitions and their associated event counts, incidence-densities, excess lengths of stay, and excess mortality ratios are presented below. Excess length of stay was defined as the ratio of length of stay in patients with VAP versus matched controls.

Definition

N

VAPs per 1000
vent-days

Ratio of excess ventilator days

Ratio of excess hospital days

Mortality
Odds Ratio

≥4 days ventilation, increase in ventilator support, any one of abnormal temperature, WBC count, or purulent sputum#

373

10.0

1.21
(P<.001)

1.07
(P=.07)

3.3
(P<.001)

≥4 days ventilation, increase in ventilator support, any two of abnormal temperature, WBC count, or purulent sputum#

260

7.0

1.30
(P<.001)

1.13
(P=.004)

2.7
(P<.001)

≥4 days ventilation, increase in ventilator support, abnormal temperature or WBC count, AND purulent sputum#

110

3.0

1.26
(P<.001)

1.11
(P=.15)

2.6
(P=.004)

≥4 days ventilation, increase in ventilator support, any two of abnormal temperature, WBC count, purulent sputum#, AND positive sputum culture or BAL culture

40

1.1

1.28
(P=.003)

1.20
(P=.05)

2.0
(P=.20)

#  defined as ≥25 neutrophils and ≤10 epithelial cells per low power field on gram stain microscopy

Conclusions: An objective definition for VAP based upon worsening gas exchange and any two of abnormal temperature, WBC count, or purulent sputum generates a reasonable event rate and is a highly significant predictor of increased length of stay and hospital mortality.