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Continuous gastric pH monitoring offers the opportunity to evaluate gastric acid secretion in humans without the need for collection of gastric aspirates. However, gastric emptying may be an important variable for the accurate measurement of gastric acid secretion using continuous gastric pH monitoring. We conducted an in vitro study (phase I) to evaluate the effect of gastric emptying on gastric pH. The in vitro study used a laboratory model in which continuous pH monitoring of a standard formula (Nutramigen, 100 mL) in a reservoir was performed while varying both the reservoir emptying rate (10% to 80%) over 1 hour and the amount of added acid (2 to 15 mEq/h: in vivo equivalent of 6 to 45 mEq/m2 BSA/h). An in vivo study (phase II) was then performed in 28 infants less than 6 months of age who had gastroesophageal reflux (GER) documented by 18- to 24-hour esophageal pH monitoring. At the end of esophageal pH monitoring, the pH electrode was advanced into the stomach for measurement of gastric pH continuously for 2 hours after a feeding of Nutramigen formula (300 mL/m2 BSA). Each patient also had a radionuclide gastric emptying study performed with the same volume of Nutramigen formula. In the in vitro model, the reservoir pH (% time pH less than 4) was proportional to the reservoir emptying rate only when acid was added at less than 15 mEq/h (less than 45 mEq/m2 BSA/h). Reservoir pH was independent of reservoir emptying rate when acid was added at 15 mEq/h (45 mEq/m2 BSA/h).(ABSTRACT TRUNCATED AT 250 WORDS)

Persistent gastrointestinal symptoms are common postoperatively in children with intestinal malrotation. We investigated this problem in 14 children with intestinal malrotation who had a Ladd procedure (3 patients), gastroschisis repaired (6 patients), or omphalocele repaired (5 patients) between one month and 15 years prior to study. In 13 patients, gastric emptying was measured at 30 minutes (%GE30) and at 60 minutes (%GE60) following ingestion of 99m-Tc sulfur colloid in apple juice. We estimated the degree of gastric peristalsis using the %GE corrected for immediate postcibal gastroesophageal reflux (corrected %GE). Patients with vomiting exhibited slow gastric emptying compared to patients without vomiting (%GE30: 14.0 +/- 5.5 v 32.5 +/- 4.2, P less than .005). The slow gastric emptying was related to slow gastric peristalsis (corrected %GE30: 20.3 +/- 5.0 v 47.1 +/- 6.0, P less than .005). In all 5 patients with persistent bloating and diarrhea, gastric peristalsis was rapid at 30 minutes (corrected %GE30 = 56.7 +/- 4.2) and at 60 minutes (corrected %GE60 = 69.5 +/- 5.3). To assess the role of gastroesophageal reflux (GER) in persisting symptoms, all children had extended (18 to 24 hours) esophageal pH monitoring. Eleven (79%) of the 14 patients demonstrated GER by esophageal pH monitoring, including four of six patients without reflux symptoms. All ten children under two years of age demonstrated GER regardless of symptoms or congenital anatomic abnormality. In conclusion, GER is common in patients under two years of age with intestinal malrotation, but clinical symptoms seem related more to extreme variations in gastric peristalsis than to GER.

The association of gastroesophageal reflux (GER) and gastric emptying has been observed, but its importance is poorly understood. We compared 18- to 24-hour esophageal pH recordings with gastric emptying of radionuclide in apple juice in 109 children (2 weeks to 16 years old) referred for an evaluation of GER. A pH score and the pattern of GER (type I, II, and III) were obtained by esophageal pH monitoring. Gastric emptying was measured at 30 minutes (%GE30) and at 60 minutes (%GE60). The measured gastric emptying of apple juice was similar for the normal child and for those with GER regardless of pattern type. An inverse linear correlation between postcibal reflex and measured gastric emptying was demonstrated only by the eight asymptomatic children with a normal pH score (%GE30, r = -.9603, P less than .001; and %GE60, r = -.8263, P less than .05). If the contribution of postcibal reflux on gastric emptying was eliminated, then the effective gastric emptying was increased in many children with the type I (44%, P less than .05), type II (46%, P less than .05), or type III (60%, P less than .05) pattern of GER as compared with children with a normal reflux pattern (7%). In conclusion, measured gastric emptying of clear liquids is not necessarily decreased in most children with GER. Furthermore, many children with GER demonstrate an increased effective gastric emptying even though measured gastric emptying may not appear increased.

Following antireflux surgery, children with persistent retching symptoms are presumably more likely to have delayed gastric emptying. We report 66 children between 2 weeks and 16 years of age who had an operation to control gastroesophageal reflux (GER). All patients had GER confirmed by 18- to 24-hour esophageal pH monitoring. Preoperative gastric emptying studies were performed in each patient with 99m-Tc sulfur colloid in apple juice. In addition to the percent gastric emptying (%GE), an effective gastric emptying was estimated by correcting the %GE for postcibal reflux (corrected %GE). Repeat 18- to 24-hour esophageal pH monitoring was performed postoperatively in all patients, and a repeat gastric emptying study was performed in 32 patients. After an average postoperative follow up of 6 months (range of 1 to 18 months), persistent retching was present in 12 (18%) patients. The retching was associated with dumping symptoms in six patients. Retching was seen in patients with a preoperative increase in effective gastric emptying (10/34, 29%, P less than .05) or a decrease in effective gastric emptying (2/15, 13%, NS), and not in patients with an effective gastric emptying within the control range (0/17, 0%). Postoperatively, retching with dumping symptoms was associated with an increased effective gastric emptying, and retching without dumping symptoms with a decreased effective gastric emptying. In conclusion, persistent retching followed anti-reflux surgery in children is related to extremes in effective gastric emptying. The preoperative measurement of corrected %GE identifies children at increased risk for this postoperative problem.