Abstract： Objective To investigate the effects of dynamic ventilatory factors on inflammatory response and function of extrapulmonary organs in acute respiratory distress syndrome (ARDS) dogs. Method Thirty-six healthy dogs were randomly divided into 6 groups: normal control group (N group), ARDS group ( M group) and ventilation groups (A～D groups)hased on a series of random number. The ARDS dog model was replicated by iutrawacheal instillation of hydrochloric acid and mechanical ventilation was carried out according to the following protocols. Group A:low VT, low inspiratory flow and high respiratory rate. Group B: large VT, high inspiratory flow and high respiratory rate. Group C: large VT, high inspiratory flow and low respiratory rate. Group D: large VT, low inspiratory flow and low respiratory rate. After 4 hours of mechanical ventilation, animals were sacrificed.Tumor necrosis factor (TNF)-α and intefleukin (IL)-8 levels in blood serum were measured by radioimmunoassay.Histopathological changes of liver and kidney were observed under light microscope. Results The level of IL-8 and TNF-u of group B and C were much higher than those of group D, A and M ( P<0.05), but there was no significant difference among group D, A and M ( P>0.05). The level of IL-8 and TNF-α of group N were much lower than other groups ( P<0.05). The change of histopathology was the most significant in group B and C while the change of histopathology on group C was better than group B. The change of histopathology on group A and D was better than group B and C. The change of group A was similar to group M. All the data were analyzed by statistical F test. There was statistical difference with P<0.05. Comclusions Large tidal volumes with high inspiratory flow and high respiratory rate may increase mediators of inflammation in blood sennn, and aggravate the irflamnnmtory response of extrapulmonary organs. Beducfion of inspiratory flow and respiratory rate ventilation may prevent the occurrence d multiple organ dysfunction syndrome.