Bond J H, Levitt M D, Prentiss R
J Lab Clin Med. 1975 Apr;85(4):546-55.
Pulmonary H2 excretion was used to quantitate the small bowel transit time in man. This technique is based on the observation that H2 is produced when carbohydrate is fermented by colonic bacteria and that this H2 production is reflected by a concomitant increase in breath H2 excretion. The time, therefore, between ingestion of the unabsorbable disaccharide, lactulose, and the rise in breath H2 represents the small intestinal transit time of the head of the lactulose load as it passes through the gut. Following ingestion of a mixture of polyethylene glycol (PEG) and lactulose by 9 subjects, transit time measured by H2 excretion correlated closely with the simultaneously determined time for PEG to reach the distal ileum (r equals 0.97). The ileal appearance of PEG preceded the rise in H2 excretion by a mean of 7.6 minutes. Transit time of 19 Gm. of lactulose in 40 healthy subjects averaged 72 minutes (range 25 to 118). Studies repeated 3 to 5 times in 6 subjects showed good individual reproducibility with subsequent measurements differing from initial by a mean of plus or minus 14 per cent. There was an inverse relation between transit time and dose of lactulose ingested by 9 subjects with 5, 10 and 20 Gm. of lactulose having mean transit times of 128 plus or minus 19, 94 plus or minus 15, and 40 plus or minus 8 (S$M.) minutes, respectively. This technique appears to provide a simple, safe, and noninvasive means of studying small bowel transit time in man.
肺呼出氢气量被用于测定人体小肠通过时间。该技术基于以下观察结果：结肠细菌发酵碳水化合物时会产生氢气，呼出氢气量的相应增加反映了氢气的产生。因此，摄入不可吸收的双糖乳果糖到呼出氢气量增加之间的时间，代表了乳果糖负荷头部通过肠道的小肠通过时间。9名受试者摄入聚乙二醇（PEG）和乳果糖的混合物后，通过氢气排泄测定的通过时间与同时测定的PEG到达回肠末端的时间密切相关（r等于0.97）。PEG出现在回肠的时间比呼出氢气量增加平均提前7.6分钟。40名健康受试者摄入19克乳果糖的通过时间平均为72分钟（范围为25至118分钟）。6名受试者进行3至5次重复研究显示，个体重复性良好，后续测量结果与初始测量结果的差异平均为正负14%。9名摄入5克、10克和20克乳果糖的受试者，通过时间与摄入乳果糖剂量之间呈负相关，其平均通过时间分别为128±19、94±15和40±8（标准误）分钟。该技术似乎提供了一种简单、安全且无创的方法来研究人体小肠通过时间。
