In 1997, Tremblay et al. examined the effect of ventilation strategy on lung inflammatory mediators in the presence and absence of a pre-existing inflammatory stimulus in Sprague-Dawley rats [18] . In both stimulated and nonstimulated groups, the presence of inflammatory mediators (TNF-α, IL-1β, IL-6, IL-10, macrophage inflammatory protein 2, and IFN-γ) was highest in those rats ventilated with a large tidal volume and zero PEEP. Furthermore, in a study by Ranieri et al. in 1999 [19] , the concentration of inflammatory mediators 36 hours after randomization of the groups was significantly lower in the lung-protective strategy group (tidal volume, 7.6 ± 1.1 ml/kg) than in the control group (tidal volume, 11.1 ± 1.3 ml/kg) (P < 0.05).