Effects of protective ventilation on inflammatory response of extrapulmonary organs in acute respiratory distress syndrome rabbits

Objective To evaluate the influence of protective ventilation on the inflammatory response of extrapulmonary organs in acute respiratory distress syndrome (ARDS) rabbits.Methods The ARDS rabbit model was established by saline alveolar lavage. The rabbits were divided into six groups: (1)normal;(2) ARDS group;(3) low-volume (V T) with best end-expiratory pressure (PEEP) (LVBP);(4)normal-volume(V T) with best PEEP (NVBP); (5) low-volume with high PEEP (LVHP)(6) high-volume zero PEEP (HVZP); Tumor necrosis factor (TNF)-α and interleukin (IL)-10 levels in liver and intestine homogenates were measured by ELISA and their mRNA expression RT-PCR.Results In the LVBP group, the TNF-α mRNA expression in liver was(42±9), which was lower than NVBP (56±7), LVHP (53+10), and HVZP group (70±10). But there was no different between LVBP and ARDS groups. TNF-α mRNA expression in LVHP group was higher than LVBP group in liver tissue, but lower than HVZP group significantly.Compared with LVBP group (25±9), the IL-10 mRNA expression increased significantly in NVBP (36±8), LVHP (35±5), and HVZP group (46 ± 5). Compared with LVBP group, the TNF-αand IL-10 concentrations in liver were increased markedly in NVBP, LVHP, and HVZP. But there was no difference between LVBP and ARDS group in TNF-α and IL-10 concentration in liver. Live TNF-α and IL-10 concentration was highest in HVZP group, which was higher than LVBP and LVHP group. In the LVBP group, the TNF-α mRNA expression in intestine was (38±11), which was lower than NVBP(51±9), LVHP (50±11), and HVZP group (64±11). But there was no different between LVBP and ARDS groups. The intestine TNF-α mRNA expression in LVHP group was higher than LVBP group, but lower than HVZP group significantly. As compared with LVBP group, the TNF-α concentration of intestine in NVBP, LVHP, and HVZP were markedly increased. But there was no difference between LVBP and ARDS group in TNF-α concentration of intestine. TNF-α concentration in intestine tissue was highest in HVZP group. As compared with LVBP group (22±7), the IL-10 mRNA expression in intestine increased significantly in NVBP(32 ± 7), LVHP(32 ± 8), and HVZP group (41± 5). IL-10 concentration of liver tissue in LVBP group showed no difference compared with ARDS group, but increased significantly in NVBP, LVHP, and HVZP group. IL-10 concentration in intestine tissue was highest in HVZP groups. The concentration of MPO and MDA showed no difference between ARDS and LVBP group. But compared with LVBP groups, the concentration of MPO and MDA increased significantly in NVBP, LVHP, and HVZP group.Conclusion Protective ventilation strategy can down-regulate inflammator mediator expression in the liver and intestine of ARDS rabbits and may prevent the occurrence of multiple organ dysfunction syndrome.