Table 1. VAP definition criteria evolution (10,17).

Variables	Criteria before 2013	Criteria after 2013
Respiratory status	New/worsening dyspnoea; purulent sputum; pulmonary infiltrates or consolidations on chest radiograph	≥0.20 increase in FiO2†,‡; ≥3 cmH2O increase in PEEP†,‡
Infection/inflammation	Temperature >38 °C; WBC ≥12,000 cells/mm3; antimicrobial agent not required	Temperature <36 or >38 °C§; WBC ≤4,000 or ≥12,000 cells/mm3§; one or more new antimicrobial agent required and continued for ≥4 days§
Additional data	ETT/MV during the 48 h preceding the onset of pneumonia; positive culture (ETA ≥105 CFU/mL; BAL ≥104 CFU/mL) from appropriate specimen	Gram’s staining of ETA or BAL showing ≥25 neutrophils and ≤10 epithelial cells per low-power field¶,Φ. Positive culture from: (I) ETA ≥105 CFU/mLΦ; (II) BAL ≥104 CFU/mLΦ

^†, must follow a period ≥2 days of stable or decreasing daily minimum PEEP or daily minimum FiO₂ and persist for ≥2 days; ^‡, the presence of at least one of these respiratory parameters constitutes a VAC; ^§, the presence of VAC plus one of these infection or inflammation parameters constitutes a IVAC; ^¶, the presence of IVAC plus one of this parameter constitutes a possible pneumonia; ^Φ, the presence of IVAC with both a positive Gram’s staining and a positive quantitative culture constitutes a probable pneumonia. WBC, white blood cell; ETT/MV, endotracheal intubation/mechanical ventilation; CFU, colony-forming unit; FiO₂, inspired fraction of oxygen; PEEP, positive end expiratory pressure.