侧卧位和分侧肺通气对单侧急性肺损伤犬的影响

Effects of lateral position and independent lung ventilation on unilateral acute lung injury in dogs

目的观察体位和分侧肺通气对单侧急性肺损伤(ALI)犬的影响,探讨单侧ALI时合理的机械通气方式。方法健康杂种犬28只,建立盐酸所致单侧ALI,行容量控制通气(VCV),分为常规通气组(A组)、常规通气+健侧卧位组(B组)、不同步分侧肺通气组(C组)、同步分侧肺通气组(D组)。通气240min后,每组随机选取4只犬行核素显像。监测氧合、血流动力学、呼吸力学和肺损伤指标。结果(1)通气30min后B、C、D组氧合指数(PaO2/FiO2)[(277±23)、(296±31)、(299±22)mmHg,1mmHg=0.133kPa]显著高于A组[(180±25)mmHg,P均<0.01],通气60min后C、D组PaO2/FiO2[(348±34)、(343±29)mmHg]显著高于B组[(314±33)mmHg,P均<0.05]。(2)通气120min后B组静态肺顺应性(Cst)[(23±4)ml/cmH2O]较A组[(19±2)ml/cmH2O]显著改善,通气60min后C、D组左侧Cst[(11±1)、(11±1)ml/cmH2O]均较ALI状态时显著改善[(7±2)、(6±1)ml/cmH2O,P均<0.01]。(3)B、C、D组损伤侧血流/总血流(Q损伤/Q总)[(31.3±4.6)%和(27.5±1.3)%、(27.3±2.8)%]与A组比较差异均有统计学意义[(38.3±2.2)%,P均<0.01]。结论健侧卧位和分侧肺通气均能明显改善单侧ALI犬的氧合和肺的顺应性,分侧肺通气改善氧合较健侧卧位更有效,改善氧合的机制可能与影响双侧血流分布有关。

Objective To investigate the effects of conventional ventilation, lateral position, asynchronous independent lung ventilation and synchronous independent lung ventilation on gas exchange, lung mechanics, hemodynarnics, pulmonary perfusion and inflammatory mediators in dogs with a hydrochloric acid induced unilateral acute lung injury （ALI）. Methods Twenty-eight dogs with hydrochloric acid induced unilateral ALI（the left lung） were ventilated with volume controlled ventilation. The animals were divided into four groups. The first group （group A, n = 7） received conventional ventilation in a supine position. The second group（ group B ,n =7 ） received conventional ventilation in the healthy lung dependent position with the parameters as same as group A. The third group （group C, n = 7 ） received asynchronous independent lung ventilation. The fourth group （group D, n = 7 ） received synchronous independent lung ventilation with the parameters as same as group C. All the animals were observed for 4 h under the above described ventilation. Oxygenation, lung mechanics, hemodynamics and lung injury score were measured during the ventilation. The right and left pulmonary arterial blood flows were measured after 4 h ventilation. Results （ 1 ） After 30 min ventilation, PaO2/FiO2 in group A [ （ 180 ± 25 ） mm Hg, 1 mm Hg = 0. 133 kPa ] was significantly lower than those in group B, group C and group D [ （ 277 ± 23 ）, （ 296 ± 31 ）, （ 299 ± 22 ） mm Hg respectively,all P 〈0. 01 ]. PaO2/FiO2 in group C[ （348 ± 34） mm Hg] and group D[ （343 ± 29） mm Hg] was significantly increased when compared with that of group B[ （314 ±33） mm Hg] after 60 rain ventilation（P 〈0. 05） ,but there was no significant difference between group C and group D. （2） After 120 min ventilation, Cst in group B [ （23 ± 4）ml/cm H2O ] significantly increased when compared with that of group A [ （ 19 ± 2） ml/cm H2 O, P 〈 0. 05 ]. After 60 min ventilation, C st-L in group C and group D increased significantly as compared to the beginning of the ventilation. （ 3 ） The left lung pulmonary arterial flow in groupB,group C and group D[（31.3 ±4.6）%, （27.5 ± 1.3）% and （27.3 ±2.8）%,respectively] significantly decreased when compared with that of group A （ 38.3 ± 2. 2） % after 4 h ventilation （ P 〈 0. 05 and P 〈 0. 01 ）. Conclusions Both lateral position and independent lung ventilation can improve gas exchange, while independent lung ventilation is better than lateral position ventilation. The improvement of oxygenation may be related to the effect on the distribution of pulmonary arterial flow.