The role of malabsorption in bariatric surgery

Developing a model for estimating the activity of colonic microbes after intestinal surgeries

Background

The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection.

Objective

We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps.

Methods

First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon’s microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection.

Results

For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy.

Conclusion

The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon’s microorganisms.

Resolution of late-onset heart and liver failures after reversion of jejuno-ileal bypass: a case report

OBJECTIVES

Jejuno-ileal bypass (JIB) was a kind of bariatric surgery performed from 1960s to 1980s, able to induce sustainable weight loss by creating a surgical short bowel syndrome.

MATERIALS AND METHODS

We report a case of an octogenarian woman who underwent in the early eighties this kind of surgery with consequent 40 kg weight loss. After 27 years, she first developed a reversible metabolic cardiomyopathy that began with signs and symptoms of heart failure. Thereafter, she was diagnosed with severe intractable liver insufficiency.

RESULTS

Despite her old age, the patient underwent reversal of JIB with consequent early improvement of hepatic function.

CONCLUSIONS

This case demonstrate that in case of long-term and life-threatening complications, it is possible to successfully reverse JIB surgery after upto 30 years. The hypothesis on pathophysiology of heart and liver insufficiency are discussed.

Non-alcoholic fatty liver disease and obesity: the role of the gut bacteria

Non-alcoholic fatty-liver disease (NAFLD) is now considered one of the leading causes of liver disease worldwide and is associated with metabolic syndrome and obesity. There are several factors contributing to the disease state. Recent research suggests that the intestinal microbiota (IM) and bacterial products may play a role through several mechanisms which include increased energy uptake, intestinal permeability and chronic inflammation. In addition to diet and exercise, treatment options targeting the IM are being investigated and include the use of pre-, pro- and synbiotics as well as the possibility of fecal microbial transfers. This literature review explores the relationship between NAFLD and the IM as well as highlight new IM treatment options that may become available in the near future.

High prevalence of esophageal dysmotility in asymptomatic obese patients

BACKGROUND

Obesity is an important health problem affecting >500 million people worldwide. Esophageal dysmotility is a gastrointestinal pathology associated with obesity; however, its prevalence and characteristics remain unclear. Esophageal dysmotilities have a high prevalence among obese patients regardless of gastrointestinal symptoms.

OBJECTIVE

To identify the prevalence of esophageal dysmotility among obese patients. The secondary goals were to characterize these pathologies in obese patients and identify risk factors.

METHOD

A prospective study from January 2009 to March 2010 at the University of Montreal Hospital Centre (Montreal, Quebec) was performed. Every patient scheduled for bariatric surgery underwent preoperatory esophageal manometry and was included in the study. Manometry was performed according to a standardized protocol with the following measures: superior esophageal sphincter - coordination and release during deglutition; esophageal body - presence, propagation, length, amplitude and type of esophageal waves of contraction; lower esophageal sphincter - localization, tone, release, intragastic pressure and intraesophageal pressure. All reference values were those used in the digestive motility laboratory. A gastrointestinal symptoms questionnaire was completed on the day manometry was performed. Chart reviews were performed to identify comorbidities and treatments that could influence the results.

RESULTS

A total of 53 patients were included (mean [± SD] age 43 ± 10 years; mean body mass index 46 ± 7 kg/m; 70% female). Esophageal manometry revealed dysmotility in 51% (n=27) of the patients. This dysmotility involved the esophageal body in 74% (n=20) of the patients and the inferior sphincter in 11% (n=3). Mixed dysmotility (body and inferior sphincter) was found in 15% (n=4) of cases. The esophageal body dysmotilities were hypomotility in 85% (n=23) of the patients, either from insignificant waves (74% [n=20]), nonpropagated waves (11% [n=3]) or low-amplitude waves (33% [n=9]). Gastroesophageal symptoms were found in 66% (n=35) of obese patients, including heartburn (66% [n=23]), regurgitation (26% [n=9]), dysphagia (43% [n=15]), chest pain (6% [n=2]) and dyspepsia (26% [n=9]). Among symptomatic patients, 51% (n=18) had normal manometry and 49% (n=17) had abnormal manometry (statistically nonsignificant). Among asymptomatic patients (n=18), 44% (n=8) had normal manometry and 56% (n=10) had abnormal manometry (statistically nonsignificant). Furthermore, no statistical differences were found between the normal manometry group and the abnormal manometry group with regard to medication intake or comorbidities.

CONCLUSION

Esophageal dysmotilities had a high prevalence in obese patients. Gastrointestinal symptoms cannot predict the presence of esophageal dysmotility. Hypomotility of the esophageal body is the most common dysmotility, especially from the absence of significant waves.

Effect of weight loss on sympatho-vagal balance in subjects with grade-3 obesity: restrictive surgery versus hypocaloric diet

Few and mostly uncontrolled studies indicate that weight loss improves heart rate variability (HRV) in grade-3 obesity. The aim of this study was to compare in grade-3 obesity surgery and hypocaloric diet on clinical and metabolic variables and on autonomic indices of HRV. Twenty-four subjects (body mass index, BMI 45.5 ± 9.13 kg/m(2)) underwent surgery (n = 12, gastric banding, LAGB) or received hypocaloric diet (n = 12, 1,000-1,200 kg/day). Clinical [BMI, systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate] and metabolic variables [glucose, cholesterol, HDL- and LDL-cholesterol, triglycerides, AST and ALT transaminases] and 24-h Holter electrocardiographic-derived HRV parameters [R-R interval, standard deviation of R-R intervals (SDNN); low/high-frequency (LF/HF) ratio, and QT interval] were measured at baseline and after 6 months. The two groups were identical at baseline. BMI (-7.5 ± 3.57 kg/m(2), mean ± SD), glucose (-24.1 ± 26.77 mg/dL), SBP (-16.7 ± 22.19 mmHg) and DBP (-6.2 ± 8.56 mmHg) decreased in LAGB subjects (p < 0.05) and remained unchanged in controls. At 6 months, SDNN increased in LAGB subjects (+25.0 ± 37.19 ms, p < 0.05) and LF/HF ratio diminished (2.9 ± 1.84 vs. 4.9 ± 2.78; p = 0.01), with no change in controls; LF (daytime) and HF (24 h and daytime) increased in LAGB subjects, with no change in controls. Decrease in BMI correlated with SBP and DBP decrease (p < 0.05), and DBP decrease correlated with HR decrease (p < 0.05) and QT shortening (p < 0.05). Weight loss is associated with improvement of glucose metabolism, of blood pressure, and with changes in time and frequency domain parameters of HRV; all these changes indicate recovery of a more physiological autonomic control, with increase in parasympathetic and reduction in sympathetic indices of HRV.

Early effects of gastric banding (LGB) and of biliopancreatic diversion (BPD) on insulin sensitivity and on glucose and insulin response after OGTT

BACKGROUND

Bariatric surgery improves glucose metabolism.

METHODS

To assess the direct role of surgery (i.e., independently of significant weight loss) on insulin sensitivity (homeostasis model assessment (HOMA) insulin resistance (IR) and oral glucose insulin sensitivity (OGIS)), on glucose and insulin response (area under the curve (AUC) blood glucose (BG) and AUC insulin (Ins)) to oral glucose tolerance test (OGTT), and on glucose tolerance, 11 subjects underwent OGTT (75 g, p.o.) before and 5 days after laparoscopic gastric banding (LGB; no change of initial body mass index (BMI), 46.7 +/- 2.21 kg/m(2)), and ten subjects underwent OGTT before and 7 days after biliopancreatic diversion (BPD; BMI decreased from 54.5 +/- 3.75 to 52.1 +/- 4.03 kg/m(2)). As controls, we considered OGTT performed twice over a 30-45-day period in two groups of subjects [BMI 43.0 +/- 0.41 (n = 13, matched with LGB subjects for BMI) and 48.2 +/- 0.49 kg/m(2) (n = 14, matched with BPD subjects for BMI), respectively] with stable weight (+/-1.5 kg); a further control group was made of 11 subjects with a spontaneous weight loss similar to BPD subjects (BMI from 55.5 +/- 1.27 to 52.2 +/- 1.35 kg/m(2)).

RESULTS

Fasting BG and OGIS improved in BPD subjects and in subjects with spontaneous weight loss, not in LGB subjects or in weight-stable controls; HOMA-IR, AUC BG, and AUC Ins only decreased in BPD subjects. Glucose tolerance was not affected in a different way in the various groups of subjects.

CONCLUSIONS

These data indicate an early effect of BPD different from LGB on insulin sensitivity and on glucose and on insulin response to OGTT, mostly independent of weight loss.