Acid-Base Parameters of Duodenal Contents in Man

Abstract

Aspirations of duodenal contents were made anaerobically in 57 subjects 10 cm distal to the pylorus after a liquid test meal. Of these, 25 subjects were considered to be normal in the upper, part of the gastrointestinal tract. In 15 subjects a duodenal ulcer was found. All except 14 of the normal subjects had a pentagastrin test. The aspirated samples were analyzed for p H and P co2 ; and the bicarbonate concentration was calculated from the Henderson-Hasselbalch equation. In the control group, variations of pH and P co2 with time were insignificant around a mean pH of 6.2 and a mean P co2 of 280 mm Hg. In the duodenal ulcer group, the p H was significantly lower ( P = 0.003) in the early postprandial period and the P co2 , was significantly higher (480 mm Hg) 2 hr after the meal ( P = 0.004). The high P co2 implies that, even though the p H is on the acid side of the usual neutral point of p H 7, a surplus of base is found in the contents as illustrated by the calculated bicarbonate concentrations, varying around 10 mEq per liter. The pH of the contents aspirated 1 hr after the meal and the P co2 measured 2 1/2 hr after the meal were correlated to the basal gastric acid secretion and to the peak acid output to pentagastrin. A significant negative correlation was found between duodenal pH and both basal gastric acid secretion and peak acid output to pentagastrin ( P co2 and basal gastric acid secretion ( P P