Top PDF Mechanism Underlying the Weight Loss and Complications of Roux-en-Y Gastric Bypass. Review

Mechanism Underlying the Weight Loss and Complications of Roux-en-Y Gastric Bypass. Review

Mechanism Underlying the Weight Loss and Complications of Roux-en-Y Gastric Bypass. Review

Published online: 3 November 2015 # The Author(s) 2015. This article is published with open access at Springerlink.com Abstract Various bariatric surgical procedures are effective at improving health in patients with obesity associated co- morbidities, but the aim of this review is to specifically de- scribe the mechanisms through which Roux-en-Y gastric by- pass (RYGB) surgery enables weight loss for obese patients using observations from both human and animal studies. Per- haps most but not all clinicians would agree that the beneficial effects outweigh the harm of RYGB; however, the mecha- nisms for both the beneficial and deleterious (for example postprandial hypoglycaemia, vitamin deficiency and bone loss) effects are ill understood. The exaggerated release of the satiety gut hormones, such as GLP-1 and PYY, with their central and peripheral effects on food intake has given new insight into the physiological changes that happen after sur- gery. The initial enthusiasm after the discovery of the role of the gut hormones following RYGB may need to be tempered as the magnitude of the effects of these hormonal responses on weight loss may have been overestimated. The physiological changes after RYGB are unlikely to be due to a single hor- mone, or single mechanism, but most likely involve complex gut-brain signalling. Understanding the mechanisms involved with the beneficial and deleterious effects of RYGB will speed up the development of effective, cheaper and safer surgical and non-surgical treatments for obesity.
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Age- and sex-specific effects on weight loss outcomes in a comparison of sleeve gastrectomy and Roux-en-Y gastric bypass: a retrospective cohort study

Age- and sex-specific effects on weight loss outcomes in a comparison of sleeve gastrectomy and Roux-en-Y gastric bypass: a retrospective cohort study

are no absolute BMI restrictions for RYGBP, the practice in our centre is to advise patients with a BMI ≥60.0 kg/m 2 that SG is a more appropriate procedure due to tech- nical considerations. Patients were advised to follow a two-week preoperative low energy diet, with the aim of reducing liver size. Regarding postoperative T2D manage- ment, the standard practice in our centre has been to stop glucose-lowering medications pre-discharge if glucose levels remain satisfactorily controlled off therapy. Postoper- atively, patients were advised to follow a liquid diet for two weeks, followed by softer foods for two weeks, before mov- ing onto more textured foods for the next two weeks and resuming a solid diet thereafter. Patients were subsequently reviewed in accordance with a predefined postoperative follow-up plan; telephone follow-up within a week of dis- charge from the specialist nurse, postoperative hospital clinic review at 6 weeks by the specialist nurse, at 3 months by the dietitian and surgeon, at 6 months by the surgeon and 6- to 12-monthly by the surgeon thereafter. Weight was measured at each hospital clinic visit, by a trained healthcare assistant, using a Walkthrough Platform A12SS Stainless Steel Indicator, and height was measured using a wall-mounted digital stadiometer.
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COMPARISON OF NUTRITIONAL DEFICIENCIES AND COMPLICATIONS FOLLOWING VERTICAL SLEEVE GASTRECTOMY, ROUX-EN-Y GASTRIC BYPASS,

COMPARISON OF NUTRITIONAL DEFICIENCIES AND COMPLICATIONS FOLLOWING VERTICAL SLEEVE GASTRECTOMY, ROUX-EN-Y GASTRIC BYPASS,

vitamins A, D, E, and K, zinc, and essential fatty acids (8). Although not as common as the RNY-GB, the BPD-DS procedure has been performed since the mid 1970’s in Italy and made its debut in the United States in 1988. Expected weight loss ranges from 73 - 80% of initial excess body weight (IEBW) and its mortality rate is similar to roux-en-y, 0.5% - 1.9%. A review of long-term results (9 months to over 10 years) was conducted in 987 patients with a mean BMI of 51 kg/m 2 . Satisfactory weight loss of more than 50% of IEBW was observed in 99.3% of patients (9). A study of 170 patients receiving the BPD-DS, showed that only 28% of ingested fat is absorbed after surgery, which aided in the 78.1% of excess body weight loss seen in these patients (8). One of the most serious potential nutrition complications is protein malnutrition, resulting in only 57% absorption of ingested protein as a result of intestinal bypass. This protein malabsorption is associated with hypoalbuminemia, anemia, edema, ascites, and alopecia (6).
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Maximal weight loss after banded and unbanded laparoscopic Roux-en-Y gastric bypass: a randomized controlled trial

Maximal weight loss after banded and unbanded laparoscopic Roux-en-Y gastric bypass: a randomized controlled trial

Weight regain years after surgery has clearly been asso- ciated with increased food intake over time. Flanagan [23] performed a study in which cottage cheese was given to patients at 1 month and 1 and 2 years after RYGB. They found a significant increase in cottage cheese tolerance with the increased time postoperatively, from 2.5 oz to 9 oz, on average [23]. A tolerance to larger amounts of food can be explained by 3 different anatomic changes. One is gastric pouch enlargement. Changes in pouch size have been eval- uated by some investigators. A study measuring pouch size after bariatric surgery showed a statistically significant neg- ative correlation between pouch size and the percentage of excess body weight loss at 6 and 12 months after surgery [24]. They also found that the initial gastric pouch size was a significant factor for successful weight loss, because the weight loss was significantly greater for patients with smaller pouches. A second potential mechanism is enlarge- ment of the anastomosis. It has been suggested that the size of the anastomosis controls the rate of pouch emptying [7]. The absorptive capability of the small bowel also increases with time. This has been observed in patients with the short bowel syndrome in which the intestine adapts, modifying morphologically and functionally the brush border mem- brane to increase nutrient absorption [25].
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Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy: understanding weight loss and improvements in type 2 diabetes after bariatric surgery

Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy: understanding weight loss and improvements in type 2 diabetes after bariatric surgery

Gastric restriction is a key additional weight loss mechanism after LSG. The importance of gastric restriction is highlighted by significant weight loss after other restrictive procedures like LAGB, which yield lesser gut hormone deviations (27). In head-to-head comparison, LSG produces ⬃10–15% greater EWL than LAGB (146, 212). LSG reduces gastric volume to 10% of its presurgical volume (150). This can be predicted to restrict food intake and activate stretch mechanoreceptors ear- lier, to terminate eating (satiation). In addition the potential of the removed gastric fundus to form a pseudo pouch and permit larger food volumes is lost. Currently there is no evidence that reducing bougie size, the major operative determinant of sleeve diameter, improves weight loss (56, 82). Nonetheless sleeve diameter also varies by proximity of staple line application and mechanical tissue stretch around the bougie (150), and late sleeve dilatation may be more common when larger bougie diameters are employed (213), one proposed mechanism for weight regain following LSG.
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Gastric Cancer After Roux-en-Y Gastric Bypass: A Case Report and a Systematic Review

Gastric Cancer After Roux-en-Y Gastric Bypass: A Case Report and a Systematic Review

Mean patient age was 53.1 years (range: 38-71 years). The intervals between bypass surgery and the diagnosis of cancer ranged from 1 to 22 years (mean time 9.4 years). There were 15 females (83%) and 3 males (17%), according to gender’s percentage undergoing to bariatric surgery. The symptoms and signs including: vague abdominal pain (50%) and fullness, were primarily caused by tumour obstruction, nausea and vomiting, post-prandial discomfort, gastric outlet obstruction, weight loss, abdominal distension, emesis, fullness, tarry stool (Table 2). Infrequently, the cancer of bypassed stomach is asymptomatic.
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Physiological mechanisms behind Roux-en-Y gastric bypass surgery

Physiological mechanisms behind Roux-en-Y gastric bypass surgery

Abstract: Obesity and its related comorbidities can be detrimental for the affected individual and chal- lenge public health systems worldwide. Currently, the only available treatment options leading to clini- cally significant and maintained body weight loss and reduction in obesity-related morbidity and mortality are based on surgical interventions. Apart from the ’gold standard’ Roux-en-Y gastric bypass (RYGB), the vertical sleeve gastrectomy and gastric banding are two frequently performed procedures. This review will discuss animal experiments designed to understand the underlying mechanisms of body weight loss after bariatric surgery. While caloric malabsorption and mechanical restriction are no major factors in this respect, alterations in gut hormone levels are invariably found after RYGB. However, their causal role in RYGB effects on eating and body weight has recently been challenged. Other potential factors contributing to the RYGB effects include increased bile acid concentrations and an altered composition of gut microbiota. RYGB is further associated with remarkable changes in the preference for different dietary components such as a decrease in the preference for high fat or sugar; it is important to note that the contribution of altered food preferences to the RYGB effects on body weight is not clear.
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Roux-en-Y gastric bypass (RYGB) is a well-accepted

Roux-en-Y gastric bypass (RYGB) is a well-accepted

Roux-en-Y gastric bypass is a well-accepted tool for the treatment of obesity and, compared to conventional weight loss methods (eg, diet and exercise) and other weight loss surgeries (eg, gastric banding), it results in considerable weight loss that is maintained long term. Although successful, the mechanisms for weight loss are not completely understood and it is thought that gastro- intestinal hormones play a role. Several gastrointestinal hormones have been identified for their effects on appe- tite, including glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY), leptin, and ghrelin. This review encompasses a literature search that included 45 primary articles and shows that there are alterations in GLP-1, PYY, leptin, and ghrelin postoperatively. GLP-1 and PYY concentrations were usually found to be higher, whereas ghrelin levels were typically lower post- Roux-en-Y gas- tric bypass than in individuals with obesity, those who were overweight or of normal weight, and in those who underwent procedures other than Roux-en-Y gastric by- pass or who achieved weight loss by lifestyle modification. An understanding of how gastrointestinal hormones change after Roux-en-Y gastric bypass may help dietetics practitioners optimize nutrition care for this patient pop-
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Serial changes in inflammatory biomarkers after Roux-en-Y gastric bypass surgery

Serial changes in inflammatory biomarkers after Roux-en-Y gastric bypass surgery

In another study, in a 2-year follow-up after restrictive weight loss surgery, patients showed variable changes in inflammatory markers over time [9] . In general, most inflammatory markers reached the plasma levels of con- trols at 2 years after surgery. However, during the early period, the biomarkers had either increased or showed no changes compared with baseline. This was evident across a broad range of bariatric procedures, including RYGB, biliopancreatic diversion, laparoscopic adjustable gastric band, and vertical banded gastroplasty and LapBand. This suggests that the surgery might initiate an inflam- matory state, with the reductions in biomarkers from baseline not seen until ⱖ3 months after surgery for some markers and longer for others. The complications asso- ciated with the surgery could, at least in part, underlie some of these responses in the inflammatory markers. The present study was limited in that we were unable to attain specific information on certain items, such as sur- gery duration and complications during surgery. We did eliminate patients with postoperative complications from the analysis. Another explanation for the potential delay in the reduction of the inflammatory biomarkers is that the severe energy restriction after this type of surgery leads to persistent stress that can elevate certain markers
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Complications, Mineral and Vitamin Deficiencies:  Comparison between Roux en Y Gastric Bypass  and Sleeve Gastrectomy

Complications, Mineral and Vitamin Deficiencies: Comparison between Roux en Y Gastric Bypass and Sleeve Gastrectomy

Post-operative gallbladder stones were seen with a lower frequency than in the average population. Since symptomatic gallbladder stone formation is generally a problem during weight loss and as previous studies showed a much higher incidence rate, we assume that our observation is mainly due to the prophylactic use of ur- sodeoxycholic acid (UDCA, 500 mg/day) in all patients for at least 6 months following surgery. Up to our know- ledge, there is only one publication comparing the use of UDCA following bariatric surgery prospectively [20]. Our data confirmed the observation of Miller et al., and we therefore, strongly recommend the prophylactic use of UDCA in all bariatric patients for a minimum postop- erative period of 6 months.
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Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity

Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity

In addition, the protocol did not include an upper limit for BMI, and there were a few patients with BMI above 60 in both groups. This trial cannot answer the question whether pa- tients with extremely high BMI may have greater benefit from a staged concept with initial sleeve gastrectomy followed by Roux-en-Y gastric bypass or biliopancreatic diversion. Patients and staff were not blinded to the type of operation. Both operations have specific complications (eg, internal hernia, which is only possible after Roux-en-Y gastric bypass) and phy- sicians in charge as well as patients must know what kind of op- eration was carried out. In our opinion, blinding would have been unethical.
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Body Contouring Surgery and the Maintenance of Weight-Loss Following Roux-En-Y Gastric Bypass: A Retrospective Study

Body Contouring Surgery and the Maintenance of Weight-Loss Following Roux-En-Y Gastric Bypass: A Retrospective Study

the weight loss allows patients to put back in to society i.e. return to work and this needs to be an- swered in further studies. There is evidence that BCS following bariatric surgery increases the risk of complications compared to non-BCS patients (45) and although this may not necessarily influ- ence patients satisfaction (21) the additional financial implications of this must be recognised. For- mal reporting of complication rates would add to the body of evidence required to influence funding authorities to support BCS. To further illustrate the beneficial effects of BCS for patients the resolu- tion of significant comorbidities needs to be investigated e.g. HbA1C (diabetes) and hypertension. This was unfortunately beyond the scope of this article due to insufficient follow-up data, however retrospective collection of postoperative HbA1C is currently underway and the authors hope to use the findings from this subsequent study to produce further evidence for the benefits of BCS.
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Weight regain after Roux en Y gastric bypass has a large negative impact on the Bariatric Quality of Life Index

Weight regain after Roux en Y gastric bypass has a large negative impact on the Bariatric Quality of Life Index

One limitation of this study is the lack of established definition of weight regain in the current literature. 44 Our study uses a cut-off of 15% or greater as the defini- tion of significant weight regain. This is based on liter- ature review, which reveals that previous studies have defined weight regain as gaining of a range of 5% to 30% or greater of maximal weight initially lost. 16 17 With the cut-off of 15% or greater, our study is able to show the difference in BQL Index scores between those with and without weight regain and demonstrate an associa- tion between weight regain and QoL regardless of age, BMI and years from RYGB. This suggests that a gain of at least 15% of maximal weight loss is clinically signifi- cant. A prospective study to further evaluate the effect of different levels of weight regain on QoL and health metrics is needed. Additionally, in our study, 73% of the RYGB patients consecutively recruited had weight regain. This number was higher than the prevalence of weight regain reported in previous studies. This could be due Table 2 Bariatric Quality of Life (BQL) Index scores
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Roux en Y gastric bypass: effects on feeding behavior and underlying mechanisms

Roux en Y gastric bypass: effects on feeding behavior and underlying mechanisms

Alternative candidate mechanisms (Figure 2) that might have a role in inducing the anorectic response and weight loss produced by RYGBP include changes in the secretion of bile acids (54) and the ileal-derived, bile acid–stimulated enterokine FGF-19 (91), a shift toward a “lean” gut microbiota phenotype (92), or altered vagal nerve signaling (93). Indeed, altered bile acid signaling through the farnesoid-X receptor (FXR) is thought to be a critical factor in mediating the effects of an alternative metabolic pro- cedure, sleeve gastrectomy (SG), on food intake and weight loss (94). However, there is markedly contrasting functional anat- omy between RYGBP and SG, with expedited proximal mixing of nutrients with bile acids in SG and delayed mixing at the common channel in RYGBP (Figure 2). Bile acid dynamics are thus likely to differ between procedures; indeed, differences in postprandial elevations of circulating bile acids at one year (higher in RYGBP) have been reported (95), although it is unclear whether FXR sig- naling is critical in RGYBP. Understanding the tridirectional interplay between altered microbiota, bile flow, and hormonal responses in the post-surgery intestinal milieu is increasingly viewed as key to unraveling the metabolic benefits of RYGBP (96); however, at present, mechanistic roles of altered bile acids or gut microbiota in feeding behavior changes induced by RYGBP are far less well established than the roles of gut hormones. In fact, alterations in bile flow are more likely to affect energy expendi- ture than energy intake (97), and transmission of gut microbiota from RYGBP mice to germ-free mice to germ-free mice resulted in weight loss but no effect on food intake (92). Because neural circuits ultimately determine feeding behavior, central effects on brain energy homeostatic centers are likely to be a final common pathway for each of these RYGBP effector mechanisms (Figure 2). In this regard, there has been an increasing interest in the role that altered hedonic feeding may play in mediating the effects of RYGBP on energy intake (29, 98).
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Excessive Weight Loss Following Laparoscopic Gastric Mini Bypass or Roux En Y Gastric Bypass Surgery

Excessive Weight Loss Following Laparoscopic Gastric Mini Bypass or Roux En Y Gastric Bypass Surgery

Background: More than 90 percent of obesity surgery is done using a laparoscope. This method is superior to open surgery and lead to fewer complications, shorter hospital stay and faster recov- ery. This study compared course of weight loss following laparoscopic Gastric Mini Bypass or Roux-En-Y Gastric Bypass surgery, after one year of follow up. Materials and Methods: This ran- domized clinical trial was conducted among obese patients admitted to Rasoul Akram Hospital Obesity Clinic, Half underwent laparoscopic Roux-En-Y Gastric Bypass and the rest were under- going laparoscopic Mini Gastric Bypass. The amount of weight loss during the first year after sur- gery will be discussed. Results: In this study, 75 obese patients were studied. Most of the partici- pants were female (82.7%). Participants aged between 18 and 59 years old (average = 36.8 ± 9.8 y/o). Before the surgery, there was no significant difference in weight between the two groups. Excessive weight loss after one month, six months nine months and one year between the two groups was significant and was more in Mini Gastric Bypass (p < 0.05). Conclusion: Respecting the benefits of Mini Gastric Bypass compared to the Roux-En-Y Gastric Bypass technique, it is sug- gested for patients with morbid obesity.
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Reconstruction options following pancreaticoduodenectomy after Roux en Y gastric bypass: a systematic review

Reconstruction options following pancreaticoduodenectomy after Roux en Y gastric bypass: a systematic review

Our search returned 55 English language articles. Eight of these articles were found to specifically address PD after RYGB. In the included articles, 25 patient cases were reported; our institution included an additional case, for a total of 26 cases (Fig. 1) [13–20]. Table 1 con- tains a synopsis of all reported cases with regard to clini- copathological characteristics. Tables 2 and 3 summarize patient pre-operative, operative, and post-operative char- acteristics, respectively. Briefly, the patients were pre- dominantly female, in the sixth decade of life (median age 54 years, IQR 52–61). Median interval between gastric bypass and PD was 5 years (IQR 2–11). Patients initially presented with abdominal/back pain [18], jaun- dice [14], weight loss [9], nausea/vomiting [5], as an inci- dental finding [4], diarrhea [2], and fever/chills [1]. Computed tomography (CT) was the diagnostic modal- ity of choice in all patients. Pathological diagnoses in- cluded pancreatic adenocarcinoma [15], neuroendocrine tumors [3], chronic pancreatitis [3], bile duct fibrosis [2], intraductal papillary mucinous neoplasm [1], duodenal adenocarcinoma [1], and ampullary adenocarcinoma [1]. Procedures included pancreaticoduodenectomy [21],
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THE TECHNIQUE OF LAPAROSCOPIC Roux-en-Y gastric bypass

THE TECHNIQUE OF LAPAROSCOPIC Roux-en-Y gastric bypass

sion rate to open gastric bypass was 1%. An oral diet was begun at a mean of 1.58 days after surgery, with a me- dian hospital stay of 2 days and return to work at 21 days. The incidence of early major complications was 3.3%, and for minor complications, it was 27%. One death oc- curred, related to a pulmonary embolus (0.4%). The her- nia rate was 0.7%, and wound infections requiring out- patient drainage only were uncommon (5%). Excess weight loss was 83% at 24 months and 77% at 30 months. In patients with more than 1 year of follow-up, most of the comorbid conditions had abated or resolved, and 95% reported a significant improvement in quality of life. Our current experience involves approximately 2000 patients with up to nearly 6 years of follow-up. Most of them un- derwent the gastrojejunostomy with linear stapler tech- nique and received an antecolic, antegastric Roux-limb. Mean excess weight loss appears to be maintained at 65% to 70% at 5 years (unpublished data). Our experience sug- gests that laparoscopic Roux-en-Y gastric bypass effec- tively achieves sustained weight loss, relieves comorbid conditions, improves quality of life, and reduces recov- ery time and perioperative complications.
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SUMMARY We hypothesize that sleeve gastrectomy reduces bone loss as compared to Roux-en-Y gastric bypass.

SUMMARY We hypothesize that sleeve gastrectomy reduces bone loss as compared to Roux-en-Y gastric bypass.

The number of sleeve gastrectomies being performed in the United States is increasing exponentially. While the weight loss achieved by sleeve gastrectomy is more similar to Roux- en-Y gastric bypass than adjustable gastric banding, the procedure is generally thought to be restrictive. How does sleeve gastrectomy change bone mineral density? There are no published studies to address this question. What is the appropriate bariatric procedure in a patient with increased risk of developing osteoporosis? We hypothesize that sleeve gastrectomy reduces bone loss as compared to Roux-en-Y gastric bypass. And therefore sleeve gastrectomy may be the preferred treatment for morbidly obese patients that have high risk factors for developing osteoporosis such as the postmenopausal female patient.
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The comparison of effects of Roux-n-y gastric bypass and sleeve gastrectomy on excess weight loss in morbidly obese patients

The comparison of effects of Roux-n-y gastric bypass and sleeve gastrectomy on excess weight loss in morbidly obese patients

However, in some randomized studies, it was reported that SG had similar results to RYGBP. LSG is a straightforward procedure that can usually be achieved laparoscopically, even in the case of an extremely obese patient. In addition, there is no digestive anastomosis, no mesenteric defects with the risk of internal hernia, no foreign material as in the case of gastric banding, and no dumping syndrome. The risk of peptic ulcers is low, and the gastrointestinal tract is suitable for gastroscopic evaluation. 16

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LAPAROSCOPIC ROUX-EN-Y GASTRIC BYPASS FOR MORBID OBESITY CASE REPORT

LAPAROSCOPIC ROUX-EN-Y GASTRIC BYPASS FOR MORBID OBESITY CASE REPORT

4. FRANJIć BD, PULJIZ Z, GRGIć T, et al. Laparoscopic surgery in the treatment of morbid obesity: first experiences with the Swedish adjustable gastric band at Sestre milosrd- nice University Hospital. Acta Chir Croat 2004;1:9-13. (in Croatian)

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