Ohri S K, Bowles C T, Siddiqui A, Khaghani A, Keogh B E, Wright G, Yacoub M H, Taylor K M
Department of Surgery, Hammersmith Hospital, Royal Postgraduate Medical School, London, UK.
Perfusion. 1994 Mar;9(2):101-8. doi: 10.1177/026765919400900204.
In a study to assess the potential effect of nonpulsatile hypothermic cardiopulmonary bypass (CPB), intramucosal pH (pHi) of the gastric and colonic mucosae was determined by tonometry (n = 8). During the hypothermic phase of CPB, gastric and colonic pHi did not change significantly. Forty minutes after the start of rewarming, despite increases in the cardiac index and mean arterial blood pressure, gastric pHi fell from 7.53 +/- 0.02 to 7.31 +/- 0.03 (p = 0.017) and colonic pHi fell from 7.50 +/- 0.02 to 7.32 +/- 0.03 (p = 0.028). Forty minutes after the end of CPB both the colonic (p = 0.017) and gastric (p = 0.046) pHi remained depressed below pre-CPB values. The difference in the arterial (pHa) and the gastric mucosal pH changed from -0.097 before CPB to 0.016, 40 minutes after the end of CPB (p = 0.027). This alteration in the pHa-pHi underlines the importance of measuring intramucosal pH by tonometry, since the pHa and pHi may move in opposite directions during episodes of haemodynamic stress. Both the gastric and colonic pHi were found to have a linear correlation with the pHa, although changes in the gastric pHi (r = 0.41, p = 0.018) were more strongly correlated with the pHa than the colonic pHi (r = 0.23, p = 0.19) in the rewarming phase of CPB and the immediate post-CPB period when there was a tendency towards intramucosal acidosis. The development of intramucosal acidosis in the rewarming and immediate post-CPB phases following hypothermic nonpulsatile CPB may impair the gut barrier and predispose patients to the absorption of luminal toxins.
在一项评估非搏动性低温体外循环（CPB）潜在影响的研究中，通过张力测定法测定了胃和结肠黏膜的黏膜内pH（pHi）（n = 8）。在CPB的低温阶段，胃和结肠的pHi没有显著变化。复温开始40分钟后，尽管心脏指数和平均动脉血压有所升高，但胃pHi从7.53±0.02降至7.31±0.03（p = 0.017），结肠pHi从7.50±0.02降至7.32±0.03（p = 0.028）。CPB结束40分钟后，结肠（p = 0.017）和胃（p = 0.046）的pHi仍低于CPB前的值。动脉血pH（pHa）与胃黏膜pH的差值从CPB前的-0.097变为CPB结束后40分钟的0.016（p = 0.027）。pHa - pHi的这种变化突出了通过张力测定法测量黏膜内pH的重要性，因为在血流动力学应激期间，pHa和pHi可能会向相反方向变化。虽然胃和结肠的pHi都与pHa呈线性相关，但在CPB复温阶段和CPB后即刻，当存在黏膜内酸中毒倾向时，胃pHi（r = 0.41，p = 0.018）与pHa的相关性比结肠pHi（r = 0.23，p = 0.19）更强。低温非搏动性CPB后复温期和CPB后即刻黏膜内酸中毒的发生可能会损害肠道屏障，使患者易吸收肠腔内毒素。
