Effect Of Recruitment Maneuver And Tidal Volume On Alveolar Epithelium Barrier In Rat With Acute Lung Injury

Part 1. Effect of recruitment maneuver on alveolar epithelium barrier in rat with acute lung injuryObjective To evaluate the influence of recruitment maneuver (RM) on alveolar epithelium barrier in rat with acute lung injury (ALI). Methods The ALI rats model were duplicated by lipopolysaccharide iv injection. Sustained inflation (SI), as a method of RM, was applied by airway pressures of 30 cmH2O for 30 seconds. The rats were divided into four groups: (1)normal group; (2)ALI group; (3)low tidal volume (Vt) group (LV group); (4)low Vt +SI group (SI group). After 4h of mechanical ventilation, lung injury was evaluated by Smith lung injury score. Extravascular lung water (EVLW) was measured by gravimetric method. Alveolar epithelium apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL). mRNA expression of surfactant protein (SP)-C was detected by reverse transcription polymerase chain reaction (RT-PCR). Interleukin (IL)-6 and IL-10 levels in bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay (ELISA). Results Smith lung injury score and EVLW in ALI, LV and SI group were higher than that in the control group. Smith lung injury score was 2.6±0.8 in SI group, which was significantly lower than the score in ALI and LV group (7.9±1.1,5.7±0.8, q=2.201,2.201, respectively, P<0.05). A few of apoptosis epithelial cells were observed in SI group. Compared with LV group, apoptosis epithelial cells were decreased in SI group. In SI group, EVLW was lower than LV group significantly [(0.57±0.08) vs (0.68±0.05)ml, q=4.78, P<0.05]. The SP-C mRNA expressionin in SI group was higher than LV group significantly (q=2.87, P<0.05). In SI group, the concentration of IL-6 in BALF was lower than LV group [(2.52±0.93 vs 3.64±1.10)ng/ml, q=3.03, P<0.05]. There was no difference in the permeability of alveolar epithelium and the contentration of IL-10 among ALI, LV and SI group. Conclusion RM can protect alveolar epithelium barrier and down-regulate pulmonary inflammatory mediator expression in ALI.