CHANGES IN OVERNIGHT FASTING INTRAGASTRIC PH SHOW POOR CORRELATION WITH DUODENOGASTRIC BILE REFLUX IN NORMAL SUBJECTS

Background: Spontaneous rises in intragastric pH are a common phenomen on in patients and normal subjects who undergo prolonged ambulatory pH monitoring; however, controversy exists over their etiology, Some inv estigators have postulated that these events are secondary to duodenog astric bile reflux (DGBR), and others have implicated increased saliva tion or increased esophageal bicarbonate production, The advent of a f iberoptic system that reliably identifies the presence of bilirubin ha s made it feasible to qualitatively detect DGBR, We used this technolo gy along with simultaneous ambulatory intragastric pH monitoring to ev aluate the relationship between DGBR and rises in intragastric pH in n ormal subjects, Methods: We studied five normal subjects for a 15-h ov ernight period with simultaneous intragastric pH and bilirubin monitor ing, The probes were sutured together so that the pH electrode lay adj acent to the fiberoptic bilirubin sensor, then passed transnasally int o the fundus of the stomach, Subjects were fasted for the entire study , Data were obtained by plotting all intragastric pH values (recorded every 4 s) and their corresponding intragastric bilirubin absorbance u nits (recorded every 8 s) at 5-min intervals from the beginning to the end of the study for each of the five subjects (n = 903), Results: Re gression analysis of the data showed poor correlation (r = 0.26) betwe en intragastric pH and intragastric bilirubin absorbance, Conclusion: Rises in intragastic pH do not predict the presence of bile in normal subjects, In addition, DGBR usually does not cause alkaline shifts of intragastric pH, Although further studies are needed to fully elucidat e the etiology of spontaneous rises in intragastric pH, we believe tha t the measurement of ''alkaline reflux'' with ambulatory intragastric pH monitoring alone is an outdated technique and that the Bilitec 2000 should become the standard technique for the detection of intralumina l bile.