• Do Different Bariatric Procedures Have Different Effects in Different Patients?

Do Different Bariatric Procedures Have Different Effects in Different Patients?

Different endoscopic and surgical procedures for weight-loss have different effects on gastric emptying that affect weight loss, researchers report in the January issue of Clinical Gastroenterology and Hepatology. Patients should therefore be assessed for gastric emptying of solids before therapy is selected. The study found that patients with rapid gastric emptying would benefit most from a fluid-filled intragastric balloon whereas patients with slow gastric emptying would are more likely to benefit from laparoscopic sleeve gastrectomy.

Association between rate of gastric emptying (T1/2, minutes) after sleeve gastrectomy and weight loss 12 months later.

Bariatric surgery is the most effective treatment for initial and long-term weight loss, reducing comorbidities and incidence of cancer and increasing quality of life. Bariatric surgery induces restrictive, partially malabsorptive, and hormonal changes. Endoscopic bariatric therapies, such as intragastric balloons, small intestine bypass liners, and stomach remodeling techniques, have also been developed to reduce net caloric intake, mimicking perturbations generated by bariatric surgery.

However, regulation of food intake is complex, involving appetite and orexigenic signals from multiple areas in the central nervous system and gastrointestinal tract. Satiation and satiety are gastrointestinal traits are important components of appetite regulation that are controlled, in part, by rates of gastric emptying and stomach accommodation volume.

Abnormalities in these traits, such as accelerated gastric emptying, have been associated with obesity, but reported effects of bariatric surgery and endoscopic bariatric procedures on gastric emptying have varied. Each bariatric surgery and endoscopic bariatric intervention is likely to have a specific effect on gastric emptying, which in turn regulates post-intervention appetite, tolerance, and weight loss.

Eric J. Vargas et al performed a systematic review and meta-analysis of 15 studies, comprising 320 patients, to compare changes in time of gastric emptying after surgical and endoscopic bariatric procedures, including sleeve gastrectomy, Roux-en-Y gastric bypass, adjustable gastric banding, and endoscopic bariatric therapies such as intragastric balloons, botulinum toxin injections, implantable small-bowel bypass liners, and stomach remodeling techniques. They investigated their associations with gastric emptying half time (T1/2), measured before and after the procedure, and weight loss.

Vargas et al found that sleeve gastrectomy reduced gastric emptyingT1/2 by 29.2 minutes, whereas fluid-filled balloons significantly increased the gastric emptying (T1/2), by 116 minutes. Faster gastric emptying after sleeve gastrectomy was significantly associated with higher percentage of excess weight lost 12 months after this procedure (see figure).

Vargas et al found that air-filled balloons do not significantly change the time of gastric emptying, which could account for their low efficacy. Antral botulinum toxin injections produced small, temporary increases in gastric emptying time (increased T1/2 by 9.6 minutes) that were not associated with weight loss.

Changes in gastric emptying were associated with weight loss after sleeve gastrectomy and intragastric balloons, but not botulinum toxin injections.

Is gastric emptying expedited because these post-surgery stomachs have a smaller reservoir, so solids traverse at a more rapid rate, and the increase in emptying simply a byproduct that is independent of weight loss? In an editorial that accompanies the article, Reem Z. Sharaiha and Vivek Kumbhari point out that both increased and decreased gastric emptying times were associated with weight loss. So, it might just be that these changes in emptying time are only byproducts of the type of the studied bariatric procedures and not independent pathways that lead to weight loss.

There was a high level of heterogeneity among sleeve gastrectomy studies, attributable to differences in methods used to measure gastric emptying. There were insufficient studies of gastric emptying in other endoscopic approaches, such as the endoscopic sleeve gastroplasty, primary endoluminal obesity surgery, and the small-bowel implantable device EndoBarrier, to include in the meta-analysis, despite reports of their ability to delay or alter gastric emptying.

Vargas et al conclude that changes in gastric emptying time after surgical and endoscopic bariatric interventions correlate with weight loss and might be used to select interventions, based on patients’ physiology.

In their editorial, Sharaiha and Kumbhari write that patients with slower gastric emptying at baseline may not tolerate fluid-filled intragastric balloons, and might be better candidates for sleeve gastrectomy surgery or an air-filled gastric balloon. On the other hand, patients with accelerated gastric emptying at baseline might be more responsive to an intervention that significantly delays gastric emptying, such as fluid-filled intragastric balloons.

Vargas et al recommend that patients with obesity should undergo a standardized gastric emptying of solids assessment to personalize their approach with medications, endoscopic devices, and bariatric surgery. This could reduce numbers of nonresponders and maximize device efficacy and health care resources.