Effects of Laparoscopic Sleeve Gastrectomy on Gastric Structure and Function Documented by Magnetic Resonance Imaging Are Strongly Associated with Post-operative Weight Loss and Quality of Life: a Prospective Study

The role of gastric function in control of food intake (and body weight) in relation to obesity, as well as pharmacological and surgical interventions

PURPOSE

The objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.

BACKGROUND

The hormone, GLP-1, retards gastric emptying and increases gastric accommodation through vagally-mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.

SUMMARY

The motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

Effect of laparoscopic sleeve gastrectomy on drug pharmacokinetics

INTRODUCTION

Given its feasibility and efficacy, laparoscopic sleeve gastrectomy (LSG) has become a widely accepted bariatric surgery for patients with clinically diagnosed severe obesity. LSG induces anatomical changes and subsequent weight loss which may affect drug pharmacokinetics (PK) and consequently impact dosing regimens. This review aims to examine the effect of LSG on drug PK and identify relevant gastrointestinal physiological alterations.

AREAS COVERED

PubMed, Embase, Scopus, and the Cochrane Library were searched for articles related to drug PK and LSG from inception to July 2021. Moreover, literature concerning postoperative physiological conditions in the gastrointestinal tract, such as gastric pH, gastric emptying, and small bowel transit time, etc., which may affect the PK profile of drug products was also reviewed.

EXPERT OPINION

Although LSG is classified as having restrictive property without malabsorptive bypass, postoperative changes in gastrointestinal physiology and subsequent weight loss may also lead to increased, decreased or unaltered drug exposure levels. General monitoring on drug efficacy or safety using biomarkers is proposed. In addition, therapeutic drug monitoring for those drugs when it is applicable and available is recommended to ensure efficient drug dosing and avoid adverse effects. Further research into many individual drugs are warranted.

Indications and Long-Term Outcomes of Conversion of Sleeve Gastrectomy to Roux-en-Y Gastric Bypass

PURPOSE

Long-term results on sleeve gastrectomy (SG) with more than 10 years report patients needing sleeve revision for weight loss failure, de novo gastroesophageal reflux (GERD), or sleeve complications. The aim of this study was to analyze the results of laparoscopic conversion of failed SG to Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

Retrospective review of a prospectively institutional maintained database to identify patients who underwent conversion of SG to RYGB between 2012 and June 2020.

RESULTS

Sixty patients(50 females) underwent conversion to RYGB. Average time to conversion was 5.6 years (2-11). Mean %WL and TWL after SG were respectively 26±8.8% and 33.2±14.1kg. Mean BMI at the time of RYGB was 38.1±7.1 kg/m². Mean follow-up was 30.4±16.8 months (6-84). Available patients at each time of follow-up: 1 year 59 (98.3%); 2 years 47 (78.3%); 3 years 39 (71.6%); and 5 years 33 (55%). Patients were divided according to indication for revision in weight regain/insufficient weight loss (30 patients) group 1 and GERD/complications (25 patients) group 2. Percentage of excess weight loss at 1, 3, and 5 years follow-up after bypass was for group 1 40.3±17.6, 34.3±19.5, and 23.2±19.4 and for group 2 90.4±37, 62.6±28.2, and 56±35.02. Total weight loss at last follow-up since sleeve was respectively 31kg in group 1 and 46.7kg in group 2 (p=0.002). No mortality was observed. Thirty-day complication rate was 3.3%.

CONCLUSION

RYGB after SG is a safe and effective revisional procedure to manage weight regain and de novo GERD, to address complications, and to improve comorbidities.

Computational evaluation of laparoscopic sleeve gastrectomy

LSG is one of the most performed bariatric procedures worldwide. It is a safe and effective operation with a low complication rate. Unsatisfactory weight loss/regain may occur, suggesting that the operation design could be improved. A bioengineering approach might significantly help in avoiding the most common complications. Computational models of the sleeved stomach after LSG were developed according to bougie size (range 27-54 Fr). The endoluminal pressure and the basal volume were computed at different intragastric pressures. At an inner pressure of 22.5 mmHg, the basal volume of the 54 Fr configuration was approximately 6 times greater than that of the 27 Fr configuration (57.92 ml vs 9.70 ml). Moreover, the elongation distribution of the gastric wall was assessed to quantify the effect on mechanoreceptors impacting satiety by differencing regions and layers. An increasing trend in elongation strain with increasing bougie size was observed in all cases. The most stressed region and layer were the antrum (approximately 25% higher stress than that in the corpus at 37.5 mmHg) and mucosa layer (approximately 7% higher stress than that in the muscularis layer at 22.5 mmHg), respectively. In addition, the pressure-volume behaviors were reported. Computational models and bioengineering methods can help to quantitatively identify some critical aspects of the "design" of bariatric operations to plan interventions, and predict and increase the success rate. Moreover, computational tools can support the development of innovative bariatric procedures, potentially skipping invasive approaches.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

BODY-Q patient-reported outcomes measure (PROM) to assess sleeve gastrectomy vs. Roux-en-Y gastric bypass: eating behavior, eating-related distress, and eating-related symptoms

BACKGROUND

Post-operative changes in eating behavior, eating-related distress and eating-related symptoms play an important role in the lives of bariatric surgery patients. However, there are no studies that assess these outcomes using a specifically designed patient-reported outcome measure (PROM) for patients undergoing bariatric surgery. We use our newly developed and validated scales as part of the well-established BODY-Q PROMs to compare laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass patients (LRYGB).

METHODS

We analyzed data from an international multi-center prospective cohort study of patients over 18 who underwent bariatric surgery. We used multivariable linear regression models to assess the difference between LRYGB and LSG for the new BODY-Q scales, which include eating behavior, eating-related distress and eating-related symptoms. All analyses were corrected for significant confounding variables.

RESULTS

Out of 1420 patients, 920 underwent LRYGB and 500 underwent LSG. The LRYGB group had a higher percentage total weight loss (p < 0.001). There was no significant difference in eating behavior (e.g., stop eating before feeling full, avoiding unhealthy snacks, etc.) or eating-related distress (e.g., feeling ashamed or out of control after eating). Patients who underwent LSG scored significantly better on the post-prandial eating-related symptoms scale (e.g., vomiting, reflux; p < 0.001). Symptoms more prevalent in the LRYGB patients were related to dumping syndrome whereas symptoms more prevalent in LSG patients were related to reflux.

CONCLUSION

Patients who underwent LRYGB had a significantly better weight loss after surgery, but they scored worse on post-prandial symptoms in comparison to LSG patients. This information may be relevant for patients in the pre-operative counseling setting, as it may influence their decision for surgical procedure selection.