Table 1.

NHSN VAE criteria

NHSN Surveillance Guidelines for Diagnosis of VAE
Name: Description	Dependent Qualification	Definition
VAC: new respiratory deterioration	≥2 calendar days of stable or decreasing daily minimum PEEP or daily minimum Fio2	Followed by a daily Minimum PEEP of ≥3 cm H2O OR Minimum Fio 2 by >20 points sustained for ≥2 calendar days
iVAC: VAC + clinical signs of infection	Within 2 calendar days before or after onset of a VAC Excludes the first 2 d of mechanical ventilation	Temperature: <36°C or >38°C OR Leukocyte count: ≤4000 or ≥12,000 cells/mm3 AND One or more new antibiotics continued for ≥4 d
Possible VAP: IVAC + qualitative evidence of pulmonary infection	Within 2 calendar days before or after onset of a VAC Excludes the first 2 d of mechanical ventilation	Gram staining of endotracheal aspirate or BAL showing ≥25 neutrophils and ≤10 epithelial cells per low-power field OR Positive culture from sputum, endotracheal aspirate, BAL, lung tissue
Probable VAP: IVAC + quantitative evidence of pulmonary infection	Within 2 calendar days before or after onset of a VAC Excludes the first 2 d of mechanical ventilation	Positive culture of endotracheal aspirate ≥105 CFU/mL, or positive BAL culture with ≥104 CFU/mL, or positive culture of protected specimen brush ≥103 CFU/mL OR One of the following (without requirement for purulent secretions) Positive pleural fluid culture (where specimen was obtained during thoracentesis or initial placement of chest tube and NOT from indewelling chest tube) Positive lung histopathology Positive diagnostic test for legionella Positive diagnostic test on respiratory secretions for influenza virus, respiratory syncytial virus, adenovirus, parainfluenza virus, rhinovirus, human metapneumovirus, coronavirus

Highlights the stepwise respiratory deterioration associated with VAC, iVAC, possible pneumonia, and probable pneumonia with specific, objective criteria that define each category.

Sputum cultures excludes the following: normal respiratory/oral flora, mixed respiratory/oral flora or equivalent; Candida species or yeast not otherwise specified; coagulase-negative Staphylococcus species; Enterococcus species.

Abbreviations: BAL, bronchoalveolar lavage; CFU, colony-forming unit; Fio₂, fraction of inspired oxygen; PEEP, positive end-expiratory pressure.