Relationship between gastric emptying of liquid and postvagotomy diarrhoea

Effects of Gelatinization of Enteral Nutrients on Human Gastric Emptying

Background

Gastrointestinal side effects, particularly diarrhea, are still the main reasons for discontinuation of enteral nutrition. Gelatinization of liquid meal for the prevention of diarrhea has been reported as effective. The purpose of this study was to investigate the effects of gelatinization of liquid meal on gastric emptying.

Methods

Ten healthy volunteers were studied two times, with 2-week interval between tests. The total calorific value was set at 225 kcal, and 3 test meals were prepared: liquid meal and 2 types of gelatinized meals. These 2 types of gelatinized meals are different viscosity. ¹³C-sodium acetate (100 mg) was thoroughly mixed, and exhaled air was sampled. The results of gastric emptying were expressed as the time of peak excretion (T_max), and absorption was expressed as the area under the ¹³CO₂ curve up to T_max (AUC-T_max). At the same time, blood samples were collected to measure levels of blood glucose, insulin and gastrin.

Results

The mean value of T_max were 52.0, 77.3 and 85.6 min. Compared to liquid meal, gastric emptying for gelatinized meals was significantly delayed. The mean value of AUC-T_max were 22.7, 28.7 and 33.7%dose, respectively, and no significant differences in absorption were seen. No significant differences existed in blood glucose, gastrin and insulin.

Conclusions

Gelatinization of liquid meal delays gastric emptying. Gelatinized liquid meal may be useful for the management of diarrhea accompanied with enteral nutrition without influencing gastrointestinal hormone and blood glucose.

Effect of an abrupt switch from a milk-based to a fibre-based diet on gastric emptying rates in pigs: difference between origins of fibre

A characteristic dietary feature at weaning is a switch from a milk-based to plant-based diet, i.e. from a non-fibrous to a fibrous diet. The present study aimed to evaluate the effects of such an abrupt dietary switch on gastric emptying rate in pigs maintained on a milk substitute after weaning. Eighteen piglets were kept on a milk substitute for 5 weeks after weaning and were then switched to wheat-based or barley-based diets or kept on the milk substitute (six piglets per group). All piglets were fasted for 1d before the switch and daily food intake was then increased linearly to reach initial values within 3d. The gastric emptying rate was measured by γ-scintigraphy before and after the switch. Corpo-antral peristalsis was also evaluated by the use of high-frequency scintigraphic frames. The gastric emptying rate of the wheat-based diet was accelerated on days 1 to 3 after the switch, but was similar to that in the milk-substitute group thereafter. This acceleration was concomitant with an enhanced frequency of corpo-antral waves on days 2 and 3. Conversely, the gastric emptying rate of the barley-based diet tended to be enhanced on day 2, but was delayed on days 4 and 5, without any change in frequency of corpo-antral waves. We conclude that a switch from a non-fibrous to a fibrous diet alters the gastric emptying rate differently depending on the type of dietary fibre.

Acarbose treatment of infant dumping syndrome: extensive study of glucose dynamics and long-term follow-up

Dumping syndrome is a sequel of gastric surgery in adults and Nissen fundoplication in children. The syndrome is characterized by various gastrointestinal symptoms as well as irritability, diaphoresis and lethargy. Shortly after a meal, symptoms are associated with hyperglycemia (early dumping), followed by late dumping symptoms associated with reactive hypoglycemia. Several therapeutic and dietary manipulations failed to control these symptoms in previous reports as well as in an infant we have followed after Nissen fundoplication. Acarbose, an alpha-glucosidase inhibitor, has been used sporadically in adults after gastric surgery, but only once in children. In most of these studies, the effect of acarbose (on reactive hypoglycemia) was evaluated over several hours postprandially or after oral glucose load. In our study, we recorded glucose dynamics by a continuous glucose monitor system over 2 to 3 days before and during acarbose treatment, while the patient was on a well-controlled diet. These measurements (720 before and 832 on therapy) suggested that both early and late dumping symptoms are causally related to the rate of glucose elevation and decline, rather than to glucose peak and nadir, respectively. Acarbose attenuated both postprandial glucose hyperglycemia and reactive hypoglycemia, which subsequently led to a significant reduction in dumping symptoms. In a follow-up of 14 months, acarbose was well tolerated and the frequency of dumping symptoms was remarkably reduced.

Antral compensation after proximal gastric vagotomy

Proximal gastric vagotomy (PGV) has little impact on the normal pattern of solid gastric emptying, despite denervation of the proximal two thirds of the stomach and loss of the proximal gastric pump. In four healthy volunteers and four patients with PGV, we investigated the possible compensatory mechanisms that may come into play after proximal denervation of the stomach. We measured antropyloroduodenal motility with a 10-lumen sleeve/side-hole catheter for 180 minutes after ingestion of a dual-isotope radiolabeled mixed liquid/solid meal. Patients with PGV exhibited faster liquid emptying, but the rate of solid emptying was similar to that in healthy volunteers. The frequency of propagated antropyloric pressure wave was similar between the two groups, but patients with PGV exhibited less isolated pressure waves in the proximal antrum. The amplitude and duration of pressure waves recorded in the distal antrum were significantly increased in the PGV patients as compared to healthy volunteers. Although the pattern of propagated antral contractions and solid gastric emptying remains unchanged after PGV, there is an increase in the amplitude and duration of distal antral contractions, which may compensate for loss of proximal gastric pumping mechanisms.

Preservation of normal gastric emptying following gastric surgery by use of a muscle bridge

BACKGROUND

Maintenance of descending antral intramural pathways may be important in normal functioning of the pylorus after pylorus-preserving gastrectomy.

METHODS

We examined the effect of a 1-cm bridge of muscle as a means of maintaining pyloric connection to antral intramural motor control pathways in 10 pigs. Antropyloroduodenal pressures and transpyloric flow were measured during gastric emptying of saline before and after either total or subtotal transection and reanastomosis of antrum.

RESULTS

Complete antral transection shortened the time interval between antral and subsequent pyloric lumen occlusion, significantly reducing total gastric emptying and volume of transpyloric flow pulses. Subtotal transection maintained pre-transection timing and was associated with normal patterns of transpyloric flow and emptying.

CONCLUSIONS

Our results indicate that a muscle bridge is capable of maintaining normal gastric emptying and the coordination of antral with pyloric contractions. We propose that antropyloric coordination is maintained by transmission of neural signals through the muscle bridge.

Gastric motor physiology and pathophysiology

The stomach has two distinct physiologic motor areas: the proximal stomach and the distal stomach. The proximal stomach, with its slow, sustained contractions, has a key role in regulating intragastric pressure and gastric emptying of liquids, while the distal stomach, with its peristaltic contractions, has a major role in mixing, trituration, and emptying of solids. Diseases and operations that disturb the motility of these two areas can result in unique adverse motor sequelae. For example, operations that impair proximal gastric motility, such as proximal gastric resection, may cause rapid gastric emptying of liquids and subsequent dumping and diarrhea. In contrast, operations that impair distal gastric contractions, such as truncal vagotomy, may cause slow gastric emptying of solids and chronic gastric atony. Knowledge of the physiology of the stomach in health and of the pathophysiology with disease and after operation provides a basis for the successful treatment and prevention of these disorders.

Erythromycin improves emptying of the denervated stomach after oesophagectomy

Oesophagectomy, necessitating vagotomy, is associated with delayed gastric emptying. Cisapride and erythromycin have prokinetic effects and improve emptying of the innervated stomach. Their effect on the denervated stomach following oesophagectomy is unknown. The effect of pyloroplasty, cisapride and erythromycin on the rate of gastric emptying after oesophagectomy was studied using a radiolabelled meal. Oesophagectomy was associated with a marked delay in gastric emptying (56 per cent of the test meal remaining after 4 h) compared with age- and sex-matched normal controls (16 per cent; P < 0.001). Erythromycin improved the rate of gastric emptying to preoperative control values (18 per cent). Cisapride had no significant effect on gastric emptying. After pyloroplasty, 32 per cent of the label remained at 4 h (P = 0.065). The mean(s.e.m.) half-emptying time in patients receiving erythromycin was 94(29) min, which was similar to control values, 55(3) min (P = 0.26). Erythromycin may have a role in the treatment of gastric stasis following oesophagectomy or truncal vagotomy.

Isotope gastric emptying tests in clinical practice: expectation, outcome, and utility

Tests of gastric emptying with modern scintigraphic methods are recommended in the clinical management of gastric disorders. An audit of 472 gastric emptying tests carried out over a 10 year period was performed to discover the reasons for requests from consultant clinicians, their anticipation of the results of tests, and the influence of the results upon the subsequent management of their patients. Excluding control (n = 47) and research (n = 50) studies, there were 375 clinical referrals that could be grouped under the headings: non-ulcer dyspepsia (n = 72), suspected diabetic gastroparesis (n = 18), peptic ulcer (n = 15), suspected delayed gastric emptying after surgery (n = 154), dumping and diarrhoea (= 107), and other indications (n = 9). Although the results were abnormal for 55 (48%) of the 'medical' patients, they did not seem to influence clinical management. Delayed gastric emptying after surgery was confirmed in only 20% of patients referred with this clinical diagnosis. Conversely, most (79%) o the patients referred with dumping and diarrhoea exhibited abnormally rapid emptying. Isotope gastric emptying studies may be useful in clinical practice. The results are often at variance with the clinical diagnosis. Clinicians must take into account the nature of the test meal used when results are correlated with clinical features.

Postgastrectomy syndromes

Anatomic and physiological changes introduced by gastric surgery result in postgastrectomy syndromes in approximately 20% of patients. Most of these disorders are caused by operation-induced abnormalities in the motor functions of the stomach, including disturbances in the gastric reservoir function, the mechanical-digestive function, and the transporting function. Division of the vagal innervation to the stomach and ablation or bypass of the pylorus are the most significant factors contributing to postgastrectomy syndromes. Either rapid or slow emptying may result, depending on the relative importance of lack of a compliant gastric reservoir, loss of an effective contractile force, and loss of controlling factors that slow or speed gastric emptying and result in duodenal-gastric reflux. Clearly defining which syndrome is present in a given patient is critical to developing a rational treatment plan. In syndromes with slow gastric emptying, bilious vomiting, or alkaline reflux gastritis, the use of endoscopy is essential to rule out mechanical causes of the syndrome. Contrast radiography and scintigraphic gastric emptying studies are useful to document rapid or delayed gastric emptying. Postgastrectomy syndromes often abate with time. Conservative measures, including medical, dietary, and behavioral therapy, should be given at least a 1-year trial. If these nonoperative measures fail, surgical therapy is recommended. The Roux-en-Y gastrojejunostomy is useful for patients with dumping, because it slows gastric emptying and the transit of chyme through the Roux limb. The same operation helps patients with alkaline reflux gastritis, because it diverts pancreaticobiliary secretions away from the gastric remnant. Near-total gastrectomy, which reduces the size of a flaccid gastric reservoir, can be used to treat delayed gastric emptying. This operation should be combined with the Roux procedure to prevent postoperative reflux gastritis and esophagitis. Newer techniques, such as gastrointestinal pacing and the uncut Roux operation, may improve the treatment of the postgastrectomy syndromes in the future.

Treatment of severe postvagotomy/postgastrectomy symptoms with the somatostatin analogue octreotide

Fourteen patients with severe and persistent postvagotomy/postgastrectomy symptoms were entered into a trial of treatment with the somatostatin analogue octreotide, 50 micrograms twice daily 30 min before meals being self-administered by subcutaneous injection. Six of the seven patients completing the 3-month trial showed sustained overall improvement of symptoms. The remaining patients were unhelped by treatment or developed unwanted effects. Six of eight patients with dumping syndrome showed sustained improvement of dumping symptoms during treatment. Bile vomiting was relieved in three of four patients with this complaint. Diarrhoea accompanying dumping showed a variable response to treatment, with improvement in three patients and no change or worsening of this symptom in five. Two patients with severe postvagotomy diarrhoea alone showed no improvement. Four patients with unwanted effects and three patients who found no benefit stopped the trial medication early. Four further patients reported mild or transient side-effects. For patients with severe postvagotomy/postgastrectomy symptoms, a trial of octreotide seems justified when significant dumping symptoms are present and other treatment options have been exhausted.

Gastric adaptive relaxation and symptoms after vagotomy

Gastric adaptive relaxation is reported to be impaired after vagotomy. This abnormality has been implicated in the pathogenesis of postvagotomy symptoms, but no association has previously been demonstrated between the two. Gastric adaptive relaxation was measured in 15 healthy volunteers and 33 patients more than 1 year after highly selective vagotomy or truncal vagotomy and drainage. Seventeen patients were asymptomatic. The remainder were symptomatic including seven patients with persistent diarrhoea. Fasted subjects were intubated with a Ryle's tube containing a pressure microtransducer within a flaccid (800 ml) plastic bag. Gastric corpus-fundus pressure was recorded during distension of the bag with air (15 ml/s) over 30 s. Pressure indices were derived from the areas under the pressure curves. Median (range) pressure indices were: healthy volunteers 12.7 (7.5-17.1) cmH2O, highly selective vagotomy 14.0 (9.8-15.9) cmH2O (n.s.), truncal vagotomy and drainage 14.5 (8.6-26.8) cmH2O (P = 0.04). All patients with diarrhoea had abnormally high pressure indices (P less than 0.001). Pressure indices in all other patient groups were within the normal range. We conclude that gastric adaptive relaxation remains abnormal in patients with postvagotomy diarrhoea but not in those who are asymptomatic or who have other symptoms.

Role of pyloroplasty in the retrosternal stomach: results of a prospective, randomized, controlled trial

A prospective, randomized, controlled trial comparing clinical outcome and emptying of a solid meal from the retrosternal stomach, with and without pyloroplasty is described. Forty consecutive patients with oesophageal cancer undergoing retrosternal gastric reconstruction of the oesophagus were studied. In 20 patients the pylorus was left intact (group 1) and 20 patients underwent an Aust pyloroplasty (group 2). Nine patients in group 1 suffered postoperative symptoms of gastric stasis compared with only one patient in group 2 (P = 0.0106). Three patients in group 1 died from aspiration pneumonia before discharge from hospital. A gastric emptying test was performed on 24 patients between 1 and 3 months after surgery. By this time, most survivors had recovered from symptoms attributed to gastric stasis and no significant difference in gastric emptying could be demonstrated between the two groups. Selection of patients, a wide range of emptying times and improvement in gastric emptying on follow-up may explain the lack of correlation between postoperative symptomatology and the gastric half-emptying times. A pyloroplasty is advised to prevent the potentially lethal effects of gastric stasis in the early postoperative period following retrosternal reconstruction of the oesophagus.

Highly selective vagotomy combined with cholecystectomy: is there an increased risk of diarrhea?

The addition of cholecystectomy to truncal vagotomy and a drainage procedure increases the incidence and severity of postvagotomy diarrhea. This study attempts to establish whether diarrhea is more common after highly selective vagotomy (HSV) and cholecystectomy than after HSV alone. The incidence of diarrhea in 729 patients who underwent HSV without cholecystectomy was found to be 8.8% whereas, in 66 patients in whom HSV was combined with cholecystectomy, the incidence of diarrhea was 9.3%. In most patients, the diarrhea was very mild and in none was it severe. We conclude that the addition of cholecystectomy to HSV does not result in an increased incidence of diarrhea.

Mechanisms governing the biphasic pattern of gastric emptying after truncal vagotomy and pyloroplasty

The pattern of gastric emptying after truncal vagotomy and drainage is usually biphasic. An early rapid phase is followed by a characteristically abrupt transition to slow emptying. The mechanisms responsible for this pattern were studied in six dogs with truncal vagotomy and pyloroplasty, fitted with a proximal duodenal cannula. Gastric emptying was measured using gamma camera imaging of a radiolabelled 15% dextrose test meal. Sixty one hour studies were done using five designs. (1) With the cannula closed gastric emptying was initially rapid, followed by stasis (emptying at 15 min - 32% (5.3), 60 min - 34% (4.8); mean (SE)). (2) With the cannula open emptying was very rapid (15 min - 76% (4.2) p less than 0.001, 60 min - 88% (2.6) p less than 0.001 ANOVA). (3) Distal duodenal instillation of isotonic saline, at a rate equivalent to gastric emptying with the cannula closed, did not retard this rapid emptying (15 min - 78% (10.6), 60 min - 90% (5.4)). (4) With duodenal instillation of 15% dextrose, gastric emptying remained faster than in studies without diversion (15 min - 50% (7.0) NS, 60 min - 65% (6.8) p less than 0.01), but was slower than during diversion alone (p less than 0.05). (5) Finally, duodenal instillation of 15% dextrose before administration of the test meal produced slower initial emptying without subsequent stasis (15 min - 24% (4.5), 60 min - 47% (10.6)), although the amounts emptied were not significantly different from those with the cannula closed. These results indicate that after truncal vagotomy and pyloroplasty small bowel resistances play a significant role in controlling gastric emptying. Osmoreceptor responses persist after truncal vagotomy, but sympathetic inhibitory responses to small bowel distension are not involved in the regulatory process.