休克再灌注期间肠粘膜pH及肠粘膜与动脉血二氧化碳分压差的变化

Changes in colonic intramucosal pH and PCO_2 gradient between colonic mucosa and arterial blood during hemorrhagic shock and reperfusion in rabbits

目的：探讨低血容量性休克及再灌注时肠粘膜ｐＨ（ｐＨｉ）及肠粘膜与动脉血二氧化碳分压（ＰＣＯ２ ）差（Ｐｉ－ ａＣＯ２ ）的变化及意义。方法：采用兔低血容量性休克及再灌注模型，通过Ｔｏｎｏｍ ｅｔｒｙ 张力计测定并计算休克前（Ｓ０ ）、休克１ 小时（Ｓ１）及再灌注１ 小时（ＲＥＰ１ ）、２ 小时（ＲＥＰ２ ）乙状结肠ｐＨｉ及Ｐｉ－ ａＣＯ２ ，同时监测血流动力学及氧指标，并依据ｃｈｉｕ 法观察ＲＥＰ２ 时肠粘膜病理改变分级。结果：Ｓ１、ＲＥＰ１ 及ＲＥＰ２ ３个时点乙状结肠ｐＨｉ显著低于对照组和Ｓ０，而Ｐｉ－ ａＣＯ２ 明显高于对照组和Ｓ０ （Ｐ均＜ ０．０１），且ＲＥＰ１ 、ＲＥＰ２ 与Ｓ１ 时ｐＨｉ及Ｐｉ－ ａＣＯ２ 无差异。ＲＥＰ２ 时肠粘膜损伤（肠上皮坏死脱落）为Ⅱ～Ⅲ级并与ｐＨｉ正相关。与乙状结肠ｐＨｉ及Ｐｉ－ ａＣＯ２ 变化不同，再灌注期间全身氧指标和血流动力学基本恢复至休克前水平。结论：休克缺血及再灌注时肠道持续低灌注及氧合障碍，ｐＨｉ及Ｐｉ－ ａＣＯ２ 是反映该状态特异灵敏的指标。

Objective:To investigate changes in colonic intramucosal pH (pHi) and PCO 2 gradient between colonic mucosa and arterial blUsing a rabbit model of hemorrhagic shockreperfusion,sigmoid colon pHi and P i-a CO 2,hemodynamics,oxygen variables were measured simultaneously before shock(S 0) and 1 hour after shock (S 1),1 hour and 2 hours of reperfusion (REP 1,REP 2).Histologic alterations in colonic tissue were examined under light microscope.Results: Sigmoid colon pHi during shock was significantly lower than that of control and preshock groups,while sigmoid colon P i-a CO 2 was obviously higher than that of control and preshock groups ( P <0 01).There was no difference in pHi and P i-a CO 2 levels between shock (1 hour) and time points of reperfusion ( P >0 05) .During reperfusion,hemodynamics and oxygen variables recovered attaining control and preshock values.A good positive correlation between colonic tissue damage and pHi was found at REP 2.Conclusions:These findings demonstrate that there is a low tissue oxygenation and hypoperfusion in digestive tract during shock and reperfusion,and pHi and P i-a CO 2 are better indicators for this status.