Verdú E F, Fraser R, Murphy G M, Blum A L, Armstrong D
Division of Gastroenterology, CHUV, Lausanne, Switzerland.
Scand J Gastroenterol. 1995 Oct;30(10):935-43. doi: 10.3109/00365529509096335.
Duodenogastric reflux (DGR) can produce transient increases in gastric luminal pH. It has been proposed that intragastric pH-metry is a reliable method for the detection of DGR. Our aim was to test the hypothesis that nocturnal increases in antral pH are due solely to DGR.
Gastric pH was monitored overnight using two glass pH electrodes, one in the antrum adjacent to the tip of a nasogastric tube and one in the corpus. Scheduled antral aspirations were performed hourly to determine base-line concentrations of total bile acids (TBA; a marker of DGR) and thiocyanate (SCN; a marker of swallowed saliva). Additional, triggered aspirations were performed if antral pH exceeded 3.0 for 1 min or more (PHAP; period of high antral pH). TBA and SCN were considered to be increased if they exceeded the 90th percentile of values determined in scheduled aspirates (TBA, 0.88 mM; SCN, 0.67 mM).
In 28 of the 62 samples whose aspiration was triggered by a PHAP the pH was less than 3.0, and the sample was not considered to be representative. In the remaining 34 samples the antral luminal pH and the sample pH were concordant; TBA alone was increased in 6 samples, SCN alone was increased in 6 samples, and TBA and SCN were both increased in another 3 samples. Thus, DGR and swallowed saliva alone or in combination accounted for only 15 (45%) of the PHAP in which adequate gastric samples were obtained.
Samples of gastric antral contents often do not reflect accurately the acidity of gastric fluid in contact with a luminal antral pH electrode. Nocturnal increases in antral pH, detected by a luminal electrode, are frequently due to mechanisms other than duodenogastric reflux or swallowed saliva. Thus, antral pH-metry is not suitable for monitoring the occurrence of duodenogastric reflux.
十二指肠-胃反流（DGR）可导致胃腔内pH值短暂升高。有人提出，胃内pH值测定是检测DGR的可靠方法。我们的目的是检验夜间胃窦pH值升高仅由DGR引起这一假设。
使用两根玻璃pH电极对胃pH值进行整夜监测，一根置于靠近鼻胃管尖端的胃窦处，另一根置于胃体部。每小时定时进行胃窦抽吸，以测定总胆汁酸（TBA；DGR的标志物）和硫氰酸盐（SCN；吞咽唾液的标志物）的基线浓度。如果胃窦pH值超过3.0持续1分钟或更长时间（高胃窦pH期，PHAP），则进行额外的触发抽吸。如果TBA和SCN超过定时抽吸测定值的第90百分位数（TBA，0.88 mM；SCN，0.67 mM），则认为其升高。
在62个因PHAP触发抽吸的样本中，有28个样本的pH值低于3.0，该样本不被视为具有代表性。在其余34个样本中，胃窦腔内pH值与样本pH值一致；仅TBA升高的样本有6个，仅SCN升高的样本有6个，TBA和SCN均升高的样本有3个。因此，单独或联合存在的DGR和吞咽唾液仅占获得足够胃样本的PHAP的15个（45%）。
胃窦内容物样本通常不能准确反映与胃窦腔内pH电极接触的胃液酸度。通过腔内电极检测到的夜间胃窦pH值升高，通常是由十二指肠-胃反流或吞咽唾液以外的机制引起的。因此，胃窦pH值测定不适用于监测十二指肠-胃反流的发生。
