动态通气参数对急性呼吸窘迫综合征犬肺损伤的作用机制

Effects of inflammatory mediators and mechanism of dynamic factors on lung injury in a dog model of acute respiratory distress syndrome

目的探讨机械通气动态通气参数对ARDS犬肺内肺炎症介质的影响及其作用途径。方法取36条健康杂种犬，采用气管内盐酸吸入法建立ARDS模型，随机（随机数字法）分为对照组，ARDS模型组及实验犬组，实验犬组随机分成A，B，C，D四组，每组6条。A组：小潮气量（6mL／kg），低吸气流速[6mL／（kg·s）]，高通气频率（30次／min）；B组：大潮气量（20mL／kg），高吸气流速[20mL／（kg·s）]，高通气频率（30次／min）；C组：大潮气量（20mL／kg），高吸气流速[17mL/（kg·s）]，低通气频率（15次／min）；D组：大潮气量（20mL／kg），低吸气流速[10mL／（kg·s）]，低通气频率（15次／min）。机械通气4h后处死动物，留取肺组织标本行免疫组化、Western blotting检测TNF-α，IL-8，p38MAPK蛋白的变化，RT-PCR测定TNF-α，IL-8mRNA的表达，流式细胞仪检测NF-κB活性。结果B组IL-8蛋白表达明显较A，D组高，C组IL-8蛋白表达较B组有下降趋势，但B，C组之间差异无统计学意义；B组INF-α的灰度比值明显较其他组高（P〈0．01），但与C组比较差异无统计学意义（P〉0．05）；B组p38MAPK表达明显较A，D组高（P〈0．01）；A，D组之间的p38MAPK表达差异无统计学意义（P〉0．05）。B组NF-κB1065（33．56±2．85）％表达较A（10．35±0．6）％，D（7．11±0．47）％两组差异有统计学意义，B组与C组（30．87±1．16）％之间差异无统计学意义。结论在相同的大潮气量基础上，高吸气流速和高通气频率可以激活肺组织p38MAPK及NF-κB通道，炎症介质的释放增加，导致呼吸机相关性肺损伤，小潮气量机械通气可减轻炎症反应。

Objective To evaluate the effect on inflammatory mediators and mechanism of dynamic factors on lung injury in a dog model of acute respiratory distress syndrome （ARDS）. Method The ARDS dog model was duplicated by instillation hydrochloric acid. The dogs were randomly （random number） divided into six groups： （1） normal control group （N group）; （2） ARDS group （M group）; （3） low VT （6 mL/kg） at respiratory rate 30, low inspiratory flow 6 mL/（kg·s）. （4） large VT （20mL/kg） at respiratory rate 30, high inspiratory flow 20 mL/kg·s. （5） large VT （20 mL/kg） at respiratory rate 15, high inspiratory flow 17 mL/（kg· s）. （6） large VT （20 mL/kg） at respiratory rate 15, low inspiratory flow 10mL/（kg· s）. All the dogs were killed after 4 h ventilation. TNF-α,IL-8, p38 MAPK and NF-κB activity in the lung were measured. Results The expression of IL-8 protein in B and C groups was much higher than that of other groups （ P 〈 0.01） .There was no significant difference among M, A and D groups （ P 〉 0.05）. The gray scale ratio of B group was obviously higher than that of other groups （P 〈 0.01）, except C group （P 〉 0.05）. There was no significant changes among M, A and D groups in TNF-α protein contents, p38 MAPK value of positive staining of B group was the strongest, significantly higher than that of D group （ P 〈 0.01） .The expression of !o38 MAPK in B and C groups was much higher than other groups （P 〈 0.01）. NF-κB activity in B group （33.56 ± 2.85% ） was significantly higher than that in A （10.35±0.6%）,D（7.11± 0.47%） group, but there was no difference between B and C group （30.87 ±1.16%）. Conclusions Ventilation at high tidal volan：e, high inspiratory flow rate, high respiratory rate could activate p38 MAPK and increase the activity of NF-κB with the result of aggravating the release of inflammatory mediators, p38 MAPK and NF-κB activation are the major mechanisms in the development of VILI.