Postprandial Acid Reflux is Reduced by Delayed Gastric Emptying

Postprandial proximal gastric acid pocket and gastroesophageal reflux disease

An unbuffered layer of acidity that escapes neutralization by food has been demonstrated in volunteers and gastroesophageal reflux disease patients. This postprandial proximal gastric acid pocket (PPGAP) is manometrically defined by the presence of acid reading (pH<4) in a segment of the proximal stomach between nonacid segments distally (food) and proximally (lower esophageal sphincter or distal esophagus). The PPGAP may have important clinical implications; however, it is still poorly understood. Gastric anatomy and physiology seem to be important elements for PPGAP genesis. Gastric operations and acid suppression medications may decrease distal - proximal intragastric acid reflux and help control gastroesophageal reflux.

Postprandial proximal gastric acid pocket and gastric pressure in patients after gastric surgery

BACKGROUND

An unbuffered postprandial proximal gastric acid pocket (PPGAP) has been demonstrated in normal individuals (NI) and patients with gastro-esophageal reflux disease (GERD). The role of gastric anatomy and gastric motility in the physiology of the PPGAP remains elusive. This study aims to analyze the correlation of PPGAP with proximal gastric pressure after gastric surgery.

METHODS

A total of 26 individuals were studied: eight patients after open Roux-en-Y gastric bypass (RYGB) for morbid obesity, six patients after laparoscopic Nissen fundoplication for GERD, seven patients after open subtotal gastrectomy for gastric cancer and five NI. Patients underwent high resolution manometry to identify the location of the lower border of the lower esophageal sphincter (LBLES) and measure gastric pressure 1, 2, 3, 4 and 5 cm below the LBLES, immediately before swallow and after the end of the LES relaxation. A station pull-through pH monitoring was performed in all but NI, from 5 cm below the LBLES to the LBLES in increments of 1 cm in a fasting state and 10 min after a standardized fatty meal.

KEY RESULTS

Our results show that: (i) proximal gastric pressures are lower after swallow compared with before swallow in NI; (ii) patients after gastric surgery tend to have higher gastric pressure before and lower after swallow compared with NI and (iii) patients after RYGB with PPGAP have an increased gastric pressure after swallows in the segment where the PPGAP is noticed.

CONCLUSIONS & INFERENCES

Gastric motility may play a role in the genesis of PPGAP in patients after RYGB. The contribution of gastric motility for the genesis of PPGAP is still elusive in other patients.

The role of delayed gastric emptying and impaired oesophageal body motility

Delayed gastric emptying in a variable proportion of patients with gastro-oesophageal reflux disease has been observed in most series, however a relationship between delayed gastric emptying and increased gastro-oesophageal reflux has not been convincingly demonstrated. Enhanced postprandial accommodation and delayed emptying of the proximal stomach have been described, but some controversy exists. Impaired primary peristalsis is often present especially in patients with oesophagitis and its prevalence increases with increasing severity of inflammatory mucosal lesions. Patients with gastro-oesophageal reflux disease often have defective triggering of secondary peristalsis independently of presence of oesophagitis. It is presently unclear if impaired oesophageal motility is a primary defect or an irreversible consequence of inflammation. Attempts at pharmacological improvement of impaired oesophageal motility have been so far disappointing. Patients with partially preserved neuromuscular structures need to be identified in order to select them for new prokinetic therapy.

Effects of half-solid nutrients on gastroesophageal reflux in beagle dogs with or without cardioplasty and intrathoracic cardiopexy

BACKGROUND

Percutaneous endoscopic gastrostomy (PEG) has become an important modality to provide enteral access for long-term nutritional support. Nevertheless, aspiration of liquid nutrients due to vomiting and reflux esophagitis caused by gastroesophageal reflux (GER) is a significant problem associated with tube feeding by PEG.

MATERIALS AND METHODS

First, gastrostomy as an access for enteral nutrition and esophagostomy for gastroesophageal pH and Bilitec monitoring were performed in eight beagle dogs, in which the influence of viscosity of an enteral formula on the degree of GER was investigated using a commercially available liquid meal and a nearly isocaloric half-solid diet that was prepared by adding a solution mixed with dextrin, pectin, and calcium lactate. Second, similar studies were accomplished in seven beagle dogs that underwent cardioplasty and intrathoracic cardiopexy (a model of GER disease [GERD]).

RESULTS

There was no difference in the degree of GER evaluated by Bilitec monitoring between liquid and half-solid nutrients in eight normal dogs, whereas solidifying nutrients significantly reduced the frequency of reflux during the feeding periods (P=0.0180) and post-feeding periods (P=0.0277) in a model of GERD.

CONCLUSION

The use of half-solid nutrients for enteral feeding reduced the frequency of reflux in a dog model of GERD.

Postprandial gastric antral contractions in patients with gastro-oesophageal reflux disease: a scintigraphic study

Disturbed gastric contractility has been found in manometric studies in patients with gastro-oesophageal reflux disease (GORD), but the pathophysiological role of this abnormality is unclear. We aimed at assessing postprandial gastric antral contractions and its relationships with gastric emptying and gastro-oesophageal reflux in GORD patients. Fasted GORD patients (n = 13) and healthy volunteers (n = 13) ingested a liquid meal labelled with 72 MBq of 99mTechnetium-phytate. Gastric images were acquired every 10 min for 2 h, for measuring gastric emptying half time. Dynamic antral scintigraphy (one frame per second), performed for 4 min at 30-min intervals, allowed estimation of both mean dominant frequency and amplitude of antral contractions. In GORD patients (n = 10), acidic reflux episodes occurring 2 h after the ingestion of the same test meal were determined by ambulatory 24-h oesophageal pH monitoring. Gastric emptying was similar in GORD patients and controls (median; range: 82 min; 58-126 vs 80 min; 44-122 min; P = 0.38). Frequency of antral contractions was also similar in both groups (3.1 cpm; 2.8-3.6 vs 3.2 cpm; 2.4-3.8 cpm; P = 0.15). In GORD patients, amplitude of antral contractions was significantly higher than in controls (32.7%; 17-44%vs 23.3%; 16-43%; P = 0.01), and correlated positively with gastric emptying time (R(s) = 0.58; P = 0.03) and inversely with the number of reflux episodes (R(s) = -0.68; P = 0.02). Increased amplitude of postprandial gastric antral contractions in GORD may comprise a compensatory mechanism against delayed gastric emptying and a defensive factor against acidic gastro-oesophageal reflux.

Gastroesophageal reflux and gastric emptying, revisited

Total gastric emptying is delayed in 10% to 33% of adult patients with gastroesophageal reflux disease (GERD), but a strong correlation between duration of gastric emptying and severity of acid reflux or esophagitis has never been proved. Previous studies reported that patients with GERD might have exaggerated postprandial fundus relaxation with retention of food and triggering of transient lower esophageal sphincter relaxations (TLESRs). There is a positive correlation between postprandial fundus relaxation and number of TLESRs and also between proximal gastric emptying and esophageal acid exposure. However, new studies suggest that a high number of TLESRs and reflux events may occur even with accelerated gastric emptying, and prolonged gastric retention might be associated with less rather than more esophageal acid exposure. Using simultaneous gastric emptying and esophageal pH impedance we found that the rate of gastric emptying might determine the acidity and proximal extent of reflux: The slower the emptying, the higher the pH and proximal extent of the refluxate.