【摘要】 目的 观察两种通气模式的大鼠机械通气相关性肺炎(VAP)模型中肺组织β-防御素-2的基因和蛋白质表达水平。方法48只健康清洁级雄性SD大鼠被随机分成GMV组和PHY+PEEP组。每只大鼠机械通气24 h后,从气管导管中注入铜绿假单胞菌0.2 ml复制VAP模型。采用RT-RNA和Western blot技术测定实验RBD-2 mRNA和蛋白质表达的变化。结果 GMV组重度肺组织病理变化明显高于PHY+PEEP组;GMV组中RBD-2基因和蛋白质的表达上调的水平在3h后时段显著低于PHY+PEEP组(P<0.05)。结论 允许性高碳酸血症加最佳PEEP通气模式对肺Ⅱ型细胞β-防御素-2 mRNA和蛋白质表达上调水平的影响小,能预防或减缓机械通气相关性肺炎的发生发展。更多还原

【Abstract】 Objective To evaluate the effects of conventional mechanical ventilation (CMV) and mechanical ventilation with ideal PEEP and permissive hypercapnia (PHY + PEEPi) on expression of β-defensin-2 (HBD-2) gene and protein in ventilator-associated pneumonia (VAP). Methods Forty-eight male SD rats weighing 280-320 g were randomly divided into 2 groups: (1) CMV group (VT = 12 ml· kg-1 , RR = 70bpm, FiO2 = 1.0) (n = 24) and (2) PHY + PEEPi group (VT =6 ml·kg-1 , RR = 90bpm, PEEP = 0.2 kPa, FiO2 = 1,0) (n = 24) . The animals were anesthetized with intraperitoneal 20% urethane 1 ml·100 g-1 , tracheotomized and mechanically ventilated. After being ventilated for 24 h P. aeruginosa (3 × 108 CFU/ml) 0.2 ml was introduced into trachea to induce pulmonary infection. Three animals were sacrificed at following intervals: before and 1.5 h, 3h,6h,12h,3d and 5 d after introduction of P. aeruginosa. Lung tissaes were obtained from middle and lower lobes of left lung for microscopic examination and determination of expression of mRNA of HBD-2 by RT-PCR and HBD-2 protein level by Western blot analysis. Right lung was lavaged and broncho-alveolar lavage fluid (BALF) was collected for bacteriological examination. Results There were significantly more severe pathological changes in the lung in CMV group as compared with PHY + PEEPi group. In CMV group the levels of up-regulation of HBD-2 mRNA and protein expression were significantly lower after 3h than those in PHY + PEEPi group. The positive rate of blood and BALF bacterial culture was also higher in CMV group. The survival rate of PHY + PEEPi group was 76% , significantly higher than that of CMV group (40% ) ( P < 0.05) . Conclusions Mechanical ventilation with permissive hypercapnia (low VT) and low PEEP can effectively prevent VAP and decrease mortality.更多还原