PEEP及失血性休克对犬内源性一氧化氮的影响

Effects of PEEP and hemorrhagic shock on endogenous nitric oxide

目的：探讨ＰＥＥＰ及失血性休克（ＨＳ）对内源性ＮＯ的影响。方法：健康杂种犬６只在ＰＥＥＰ〔０．９８ｋＰａ，（１０ｃｍＨ２Ｏ）〕及失血性休克前后分别测定血浆中的ＮＯ浓度及肺动脉压，肺及全身血管阻力。结果：ＮＯ在ＰＥＥＰ后呈增加趋势，停止ＰＥＥＰ１０分钟后升高约２．４９μｍｏｌ／Ｌ（Ｐ＜０．０５），３０分钟后恢复至基础水平。失血性休克初始，血浆ＮＯ水平，与休克前相比差异不显著，休克３０分钟时分别比休克前及休克初始下降约３μｍｏｌ／Ｌ（Ｐ＜０．０１）和２μｍｏｌ／Ｌ（Ｐ＜０．０５）。结论：ＰＥＥＰ导致ＰＶＲＩ及ＰＡＰ升高，引起ＮＯ释放增加，有利于降低ＰＥＥＰ所致的肺动脉高压。失血性休克时，在循环指标显著降低的同时，ＮＯ浓度亦逐步下降，提示此时血压及血管阻力的降低并非由ＮＯ介导。ＮＯ的变化并不与循环指标的变化同步。

Objective:To investigate the effects of PEEP and hemorrhagic shock (HS) on endogenous NO production in six anesthetized healthy mongrel dogs Methods:After surgical preparation,all the dogs were ventilated (Simens 900B ventilator,FiO 2 0 3,20 bpm) with 10 cmH 2O PEEP lasting 20 min After spontaneous breath of 30 min,the dogs were bleeded from femoral artery to induce HS (MAP 6 kPa) The concentration of plasma NO was detected with luminol chemiluminecence technique Result:During 10 cmH 2O PEEP,pulmonary artery pressure(PAP),pulmonary vascular resistance index(PVRI) and systemic vascular resistance index(SVRI) increased significantly from 1 6±0 2 to 2 4±0 3 kPa,125 4±38 4 to 234 5±58 1 and 1974 0±333 9 to 3145 4±658 4 dyn sec -1 ·cm -5 ·m 2,respectively(P<0 01) The concentration of plasma NO unchanged significantly After withdrawal of PEEP,plasma NO level increased by 2 5 μmol/L(P<0 05)at 10 min and returned to the baseline at 30 min During HS,PAP decreased significantly(P<0 01) Plasma NO level remained stable (P>0 05) at the begining of HS,and decreased to 2 8±1 3 μmol/L(P<0 01) 30 min following HS Conclusion:The changes of endogenous NO level can play an important role in modulating pulmonary and peripheral vascular tension so as to maintain the steadiness of homeostasis during PEEP(>10cmH 2O) and HS,moreover,the changes of NO level and circulation parameters are not synchronous