犬气管插管全麻下吸入不同浓度氧时自由基及肺超微结构的变化

目的　观察犬气管插管全麻下吸入不同浓度氧时的自由基及肺超微结构变化。方法　健康杂种犬 2 0只 ,随机分为纯氧组 (1组 ,FIO2 =1,n =10 )及 4 0 %氧气组 (2组 ,FIO2 =0 4 ,n =10 )。两组麻醉方法相同 ,均行气管内插管 ,接呼吸机机械控制呼吸。监测SOD、MDA在气管插管后1、3、5、7h的变化 ,并在电镜下观察肺组织的超微结构变化。结果　 (1)与基础值比较 ,1组插管后 1、3、5、7hSOD活力明显下降、MDA值明显升高 (P <0 0 1) ;(2 )组间比较 ,1组SOD活力较 2组明显下降 (P <0 0 1)、MDA值明显上升 (P <0 0 1或P <0 0 5 ) ;(3)肺超微结构变化 ,1组观察到的肺损伤重于 2组。结论　纯氧通气氧自由基产生明显增多 ,纯氧通气 7h后观察到的肺超微结构损伤较多 ,推测氧自由基在高氧肺损伤中发挥重要作用

The effect of different concentration of oxygen inhalation on free radical and ultramicroscopic structure in dogs

Objective To observe the changes of oxygen free radical and ultrastructures with difference concentration of oxygen inhalation during general anesthesia under mechanical ventilation.Methods Twenty dogs were randomly divided into two groups:group 1(F IO 2=1, n= 10) and group 2(F IO 2=0 4, n= 10).Superoxide dismutase (SOD)activity and malonydialdehyde (MDA)level were measured at basic level 1,3,5 and 7h respectively during general anesthesia.The lung ultramicroscopic structure of two groups was inspected with electron microscopy.Results In group 1,the plasma SOD activity was decreased and MDA increased more at 1 7h( P< 0 01)than those at basic level after endotracheal intubation.Plasma SOD activity was decreased and MDA increased significantly more in group 1 than those in group 2 at 1 7h( P< 0 01) after endotracheal intubation.The pathological ultramicroscopic change of the lung tissues was more marked in group 1 than that in group 2.Conclusion Ventilation with pure oxygen can produce more oxygen free radicals,which may be an important factor leading to the pathological ultramicroscopic changes after 7h pure oxygen ventilation.