Rectal temperature >38°C or <35.5°C Blood leucocytosis (>10.10 3 /mm 3 ) and/or left shift or blood leukopenia (<3.10 3 /mm 3 ) More than ten leukocytes in Gram stain of tracheal aspirate (in high power field) Positive culture from endotracheal aspirate AND New, persistent, or progressive radiographical infiltrate cluded that blood cultures in patients with VAP are useful if there is suspicion of another probable infectious condition, but the isolation of a microorganism in the blood does not confirm that microorganism as the pathogen causing VAP. Therefore, two sets of blood samples for culture and tapping pleural effusions >10 mm should be performed in patients suspected VAP [50] .