The Use of Transient Elastography Technology in the Bariatric Patient: a Review of the Literature.

Transient elastography (TE) is a non-invasive technology that demonstrates promise in assessing liver steatosis and fibrosis without the risks of traditional percutaneous liver biopsy. Many studies have examined its reliability in respect to liver biopsy, but fewer have examined using TE in obese and bariatric surgery patients. With evidence showing that bariatric surgery can lead to improvement of liver steatosis and fibrosis, TE has the potential to provide a simple avenue of hepatic assessment in patients before and after procedures. This review article investigates what is known about the reliability of TE and its implementation in obese and bariatric surgery patients.

Conserved Metabolic Changes in Nondiabetic and Type 2 Diabetic Bariatric Surgery Patients: Global Metabolomic Pilot Study.

The goal of this study was to provide insight into the mechanism by which bariatric surgical procedures led to weight loss and improvement or resolution of diabetes. Global biochemical profiling was used to evaluate changes occurring in nondiabetic and type 2 diabetic (T2D) patients experiencing either less extreme sleeve gastrectomy or a full gastric bypass. We were able to identify changes in metabolism that were affected by standard preoperation liquid weight loss diet as well as by bariatric surgery itself. Preoperation weight-loss diet was associated with a strong lipid metabolism signature largely related to the consumption of adipose reserves for energy production. Glucose usage shift away from glycolytic pyruvate production toward pentose phosphate pathway, via glucose-6-phosphate, appeared to be shared across all patients regardless of T2D status or bariatric surgery procedure. Our results suggested that bariatric surgery might promote antioxidant defense and insulin sensitivity through both increased heme synthesis and HO activity or expression. Changes in histidine and its metabolites following surgery might be an indication of altered gut microbiome ecology or liver function. This initial study provided broad understanding of how metabolism changed globally in morbidly obese nondiabetic and T2D patients following weight-loss surgery.

Ideal Body Weight Calculation in the Bariatric Surgical Population.

BACKGROUND: In bariatric surgery, ideal body weight (IBW) is used to calculate excess body weight (EBW) and percent excess weight lost (%EWL). Bariatric literature typically uses the midpoint of the medium frame from older Metropolitan Life Insurance (MetLife) tables to estimate IBW. This is neither universal nor always clinically accurate. OBJECTIVE: The objective of this study was to determine the accuracy of standard IBW formulas compared to MetLife data. METHODS: Weight loss data from 200 bariatric surgical patients between 2009 and 2011 was used to assess the accuracy of IBW formulas. IBWs assigned from the midpoint of the medium frame and reassigned using different gender targets were compared to standard formulas and a new formula to assess the accuracy of all formulas to both targets. RESULTS: Using standard MetLife data, the mean IBW was 136 lb, the mean EBW was 153.6 lb, and the mean %EWL was 43.8 %. Using the new target baseline, the mean IBW was 137.1 lb, the mean EBW was 152.6 lb, and the mean %EWL was 44 %. Deitel and Greenstein's formula was accurate to 0.3 % of EBW using the standard method, while our new formula was accurate to 0.03 % of EBW. CONCLUSIONS: Deitel and Greenstein's formula is most accurate using standard target IBW. The most accurate is our formula using the new MetLife target IBW.

The economic costs of obesity and the impact of bariatric surgery.

The obesity epidemic has far-reaching implications for the economic and health care future in the United States. Treatments that show reduction in health care costs over time should be approved and made available to as many patients as possible. It is our opinion that bariatric surgery meets this criterion. However, bariatric surgery cannot provide the impact necessary for reduction in health care and economic costs on a national scale. The obesity epidemic must be addressed by policy efforts at the local, state, and national levels. As experts on obesity, bariatric surgeons must be prepared to guide and inform these efforts.

Decrease in sweet taste in rats after gastric bypass surgery.

BACKGROUND: The literature contains evidence that Roux-en-Y gastric bypass (RYGB) surgery has an effect in humans on taste and preference for carbohydrate-rich foods. This study tested the hypothesis that RYGB affects sweet taste behavior using a rat model. METHODS: Male Sprague-Dawley rats underwent either RYGB or sham surgery. Then 4 weeks after surgery, the rats were given taste-salient, brief-access lick tests with a series of sucrose concentrations. RESULTS: The RYGB rats, but not the sham rats, lost weight over the 5-week postoperative period. The RYGB rats showed a significant decrease in mean licks for the highest concentration of sucrose (0.25-1.0 mol/l) but not for the low concentrations of sucrose or water. CONCLUSIONS: The findings showed that RYGB surgery affected sweet taste behavior in rats, with postsurgical rats having lower sensitivity or avidity for sucrose than sham-treated control rats. This finding is similar to human reports that sweet taste and preferences for high-caloric foods are altered after bypass surgery.

Endoscopic sclerotherapy for dilated gastrojejunostomy after gastric bypass.

INTRODUCTION: Roux-en-Y gastric bypass is an excellent option for weight loss in the morbidly obese. Unfortunately, some patients do have weight regain or insufficient weight loss. Revisional bariatric surgery is not without risk. Less invasive techniques may provide alternative treatments for patients that regain weight or have insufficient weight loss. This video demonstrates a technique of endoscopic sclerotherapy for dilated gastrojejunostomy after gastric bypass. METHODS: The technique is applied to patients who have had weight regain or insufficient weight loss following gastric bypass. Patients who have lost the feeling of satiety, undergone reeducation and recounseling of dietary changes, and have documented dilated gastrojejunostomy on upper endoscopy and/or a barium study are offered this technique. If the gastojejunostomy is larger than 12 mm, sodium morrhuate is injected with an endoscopic needle circumferentially. RESULTS: The gastrojejunostomy is injected with 6-30 cc of sodium morrhuate. By visual inspection, the anastomosis usually appears smaller after the procedure. Most patients report a subjective feeling of satiety after the endoscopic sclerotherapy. Reinjection after 3 months has been performed in some patients. Except mild nausea, the patients have experienced no morbidity or mortality from the procedure. CONCLUSIONS: Endoscopic sclerotherapy may offer an alternative treatment for dilated gastrojejunostomy after gastric bypass. The technique described in the video is a relatively easy, safe method that may become the first line of therapy in patients who have a dilated gastrojejunostomy and have lost the feeling of satiety after gastric bypass with an associated weight gain.

Human epicardial adipokine messenger RNAs: comparisons of their expression in substernal, subcutaneous, and omental fat.

We compared the gene expression of inflammatory and other proteins by real-time quantitative polymerase chain reaction in epicardial, substernal (mediastinal) and subcutaneous sternal, upper abdominal, and leg fat from coronary bypass patients and omental (visceral) fat from extremely obese women undergoing bariatric surgery. We hypothesized that (1) epicardial fat would exhibit higher expression of inflammatory messenger RNAs (mRNAs) than substernal and subcutaneous fat and (2) epicardial mRNAs would be similar to those in omental fat. Epicardial fat was clearly different from substernal fat because there was a far higher expression of haptoglobin, prostaglandin D(2) synthase, nerve growth factor beta, the soluble vascular endothelial growth factor receptor (FLT1), and alpha1 glycoprotein but not of inflammatory adipokines such as monocyte chemoattractant protein-1, interleukin (IL)-8, IL-1beta, tumor necrosis factor alpha, serum amyloid A, plasminogen activator inhibitor-1, or adiponectin despite underlying coronary atherosclerosis. However, the latter inflammatory adipokines as well as most other mRNAs were overexpressed in epicardial fat as compared with the subcutaneous depots except for IL-8, fatty acid binding protein 4, the angiotensin II receptor 1, IL-6, and superoxide dismutase-2. Relative to omental fat, about one third of the genes were expressed at the same levels, whereas monocyte chemoattractant protein-1, cyclooxygenase-2, plasminogen activator inhibitor-1, IL-1beta, and IL-6 were expressed at far lower levels in epicardial fat. In conclusion, epicardial fat does not appear to be a potentially more important source of inflammatory adipokines than substernal mediastinal fat. Furthermore, the expression of inflammatory cytokines such as IL-6 and IL-1beta is actually higher in omental fat from obese women without coronary atherosclerosis. The data do not support the hypothesis that most of the inflammatory adipokines are expressed at high levels in epicardial fat of humans.

The inflammatory response seen when human omental adipose tissue explants are incubated in primary culture is not dependent upon albumin and is primarily in the nonfat cells.

BACKGROUND: The present studies were designed to investigate the changes in gene expression during in vitro incubation of human visceral omental adipose tissue explants as well as fat cells and nonfat cells derived from omental fat. METHODS: Adipose tissue was obtained from extremely obese women undergoing bariatric surgery. Explants of the tissue as well as fat cells and the nonfat cells derived by digestion with collagenase were incubated for 20 minutes to 48 h. The expression of interleukin 1beta [IL-1beta], tumor necrosis factor alpha [TNFalpha], interleukin 8 [IL-8], NFkappaB(1)p50 subunit, hypoxia-inducible factor 1alpha [HIF1alpha], omentin/intelectin, and 11beta-hydroxysteroid dehydrogenase 1 [11beta-HSD1] mRNA were measured by qPCR as well as the release of IL-8 and TNFalpha. RESULTS: There was an inflammatory response at 2 h in explants of omental adipose tissue that was reduced but not abolished in the absence of albumin from the incubation buffer for IL-8, IL-1beta and TNFalpha. There was also an inflammatory response with regard to upregulation of HIF1alpha and NFkappaB1 gene expression that was unaffected whether albumin was present or absent from the medium. In the nonfat cells derived by a 2 h collagenase digestion of omental fat there was an inflammatory response comparable but not greater than that seen in tissue. The exception was HIF1alpha where the marked increase in gene expression was primarily seen in intact tissue. The inflammatory response was not seen with respect to omentin/intelectin. Over a subsequent 48 h incubation there was a marked increase in IL-8 mRNA expression and IL-8 release in adipose tissue explants that was also seen to the same extent in the nonfat cells incubated in the absence of fat cells. CONCLUSION: The marked inflammatory response seen when human omental adipose tissue is incubated in vitro is reduced but not abolished in the presence of albumin with respect to IL-1beta, TNFalpha, IL-8, and is primarily in the nonfat cells of adipose tissue.

Dexamethasone and the inflammatory response in explants of human omental adipose tissue.

Dexamethasone is a synthetic glucocorticoid that is a potent anti-inflammatory agent. The present studies examined the changes in gene expression of 64 proteins in human omental adipose tissue explants incubated for 48h both in the absence and presence of dexamethasone as well as the release of 8 of these proteins that are putative adipokines. The proteins were chosen because they are inflammatory response proteins in other cells, are key regulatory proteins or are proteins with known functions. About 50% were significantly up-regulated while about 10% were unchanged and the remaining 40% were down-regulated. Dexamethasone significantly up-regulated the expression of about 33% of the proteins but down-regulated the expression of about 12% of the proteins. We conclude that dexamethasone is a selective anti-inflammatory agent since it inhibits only about one-fourth of the proteins up-regulated during in vitro incubation of human omental adipose tissue.

Release of 12 adipokines by adipose tissue, nonfat cells, and fat cells from obese women.

The relative release in vitro of endothelin-1, zinc-alpha2-glycoprotein (ZAG), lipocalin-2, CD14, RANTES (regulated on activation, normal T cell expressed and secreted protein), lipoprotein lipase (LPL), osteoprotegerin (OPG), fatty acid-binding protein 4 (FABP-4), visfatin/PBEF/Nampt, glutathione peroxidase-3 (GPX-3), intracellular cell adhesion molecule 1 (ICAM-1), and amyloid A was examined using explants of human adipose tissue as well as the nonfat cell fractions and adipocytes from obese women. Over a 48-h incubation the majority of the release of LPL was by fat cells whereas that of lipocalin-2, RANTES, and ICAM-1 was by the nonfat cells present in human adipose tissue. In contrast appreciable amounts of OPG, amyloid A, ZAG, FABP-4, GPX-3, CD14, and visfatin/PBEF/Nampt were released by both fat cells and nonfat cells. There was an excellent correlation (r = 0.75) between the ratios of adipokine release by fat cells to nonfat cells over 48 h and the ratio of their mRNAs in fat cells to nonfat cells at the start of the incubation. The total release of ZAG, OPG, RANTES, and amyloid A by incubated adipose tissue explants from women with a fat mass of 65 kg was not different from that by women with a fat mass of 29 kg. In contrast that of ICAM-1, FABP-4, GPX-3, visfatin/PBEF/Nampt, CD14, lipocalin-2, LP, and endothelin-1 was significantly greater in tissue from women with a total fat mass of 65 kg.

Validation that a 1-year fellowship in minimally invasive and bariatric surgery can eliminate the learning curve for laparoscopic gastric bypass.

BACKGROUND: The concept that advanced surgical training can reduce or eliminate the learning curve for complex procedures makes logical sense but is difficult to verify and has not been tested for laparoscopic Roux-en-Y gastric bypass (LRYGB). We sought to determine if minimally invasive/bariatric surgery fellowship graduates (FGs) would demonstrate complication-related outcomes (CRO) equivalent to the outcomes achieved during their training experience under the supervision of experienced bariatric surgeons. METHODS: We compared CRO for the first 100 consecutive LRYGBs performed in practice by five consecutive minimally invasive/bariatric fellows at new institutions (total 500 cases) to CRO for the 611 consecutive LRYGBs performed during their fellowship training experience under the supervision of three experienced bariatric surgeons at the host training institution. RESULTS: The two patient groups did not differ demographically. The 18 types of major and minor complications identified after LRYGB did not differ among the five fellowship graduates. The mentors' CRO were compatible with published benchmark data. As compared with the training institution data, the overall incidence of complications for the combined experience of fellowship graduates did not differ statistically from that of the mentors. The fellowship graduates' early experience included zero non-gastrojejunostomy leaks (0% versus 1.5%) and a low rate of anastomotic stricture (0.8% versus 3.0%), incisional hernia (1% versus 4.4%), bowel obstruction (0% versus 3%), wound infection (0.3% versus 3.1%), and gastrointestinal hemorrhage (0.2% versus 1.6%). The rate of gastrojejunostomy leak (1.8% versus 2.6%) and, most importantly, mortality (0.8% versus 0.7%) did not differ between the two groups. CONCLUSIONS: Fellowship graduates achieved high-quality surgical outcomes from the very beginning of their post-fellowship practices, which are comparable to those of their experienced mentors. These data validate the concept that advanced surgical training can eliminate the learning curve often associated with complex minimally invasive procedures, specifically LRYGB.

Omental reinforcement for intraoperative leak repairs during laparoscopic Roux-en-Y gastric bypass.

Leaks from the gastrojejunostomy after laparoscopic Roux-en-Y gastric bypass (LRYGB) have the potential for significant morbidity and mortality. When intraoperative leaks are discovered, we choose to perform omental reinforcement around the gastrojejunostomy and pouch after suture repair of the leaks. This study examined the hypothesis that omental reinforcement would be useful after intraoperative leaks during LRYGB. Omental reinforcement was performed on gastrojejunostomies, in which leaks were seen, created using a circular stapler during LRYGB. Data were reviewed retrospectively on these patients. There were a total of 387 patients with 32 (8.26%) patients who had a staple line dehiscence or evidence of gastric pouch or gastrojejunostomy leak intraoperatively. Leaks/dehiscences were repaired with sutures and then reinforced with omentum. None of these patient developed anastomotic leak postoperatively. Of the other 365 patients, there were four (1.1%) leaks from the gastrojejunostomy and/or gastric pouch. Omental reinforcement may be useful in decreasing the incidence of postoperative leaks when an intraoperative leak is encountered during LRYGB. However, omental reinforcement does not completely prevent a postoperative leak. Consideration of reinforcement with omentum may be given for patients in whom an intraoperative leak is noted.

Intraoperative endoscopy and leaks after laparoscopic Roux-en-Y gastric bypass.

Postoperative leaks after laparoscopic Roux-en-Y gastric bypass (LRYGB) are a source of morbidity and mortality. Any intervention that would decrease leak rates after LRYGB would be useful. This investigation tested the hypothesis that postoperative leak rates are lower after LRYGB with the routine use of intraoperative endoscopy (EN). Consecutive patients who underwent LRYGB were included. Intraoperative leak testing with air and methylene blue through an orogastric tube (OG) was used in the first 200 patients. Intraoperative endoscopy was used after the first 200 patients. There were 400 patients in this study. Preoperative demographics did not differ between groups. The intraoperative leak rate of the EN group was double the OG group (8 vs 4%; P = not significant), although the difference was not statistically significant. The OG group had a postoperative leak rate of 4 per cent with a mortality rate of 1 per cent. The EN group had a postoperative leak rate of 0.5 per cent with a mortality rate of 0 per cent. The difference in leak rates was statistically significant (P < 0.04). Despite the issues of learning curve, EN demonstrates more intraoperative leaks than OG, indicating EN may be a more sensitive test than OG. Routine use of EN is associated with less postoperative leaks after LRYGB.

Internal Hernias and Nonclosure of Mesenteric Defects During Laparoscopic Roux-en-Y Gastric Bypass.

BACKGROUND: Internal hernias have been described after laparoscopic Roux-en-Y gastric bypass (LRYGB) as a major problem. Thus, many routinely close defects during LRYGB. In our technique, we do not close any defects. We hypothesize that not closing the defects would not cause a significant internal hernia rate diagnosed during reoperations. METHODS: Patients who were reoperated after LRYGB were included in this study. Only patients who had a laparoscopic or open exploration focused on inspecting for internal hernias are reported here. The LRYGB technique that was utilized included an antecolic, antegastric gastrojejunostomy, minimal division of the small bowel mesentery, a long jejunojejunostomy performed with three staple lines, adequate division of the omentum, and placement of the jejunojejunostomy above the colon in the left upper quadrant. RESULTS: There were a total of 387 patients who had LRYGB from 2002 to 2007 utilizing this particular technique. Fifty-four patients had a reoperation at an average of 24 (Range: 1-60) months postoperatively. The procedures were abdominoplasty, cholecystectomy, diagnostic laparoscopy, and lysis of adhesions. While two patients had a defect present, no patient had an internal hernia despite aggressive attempts to diagnose one. CONCLUSIONS: Internals hernias are not common after our particular method of LRYGB. Before adopting and advocating routine closure, surgeons should consider the surgical technique and the true associated incidence of internal hernias. We do not recommend routine closure of these defects with our technique.

Patient perception of medicare fee schedule of laparoscopic procedures.

INTRODUCTION: It seems that public perception is that physicians receive substantial payments for procedures. This investigation explores patient perception and opinion of Medicare reimbursements to surgeons related to laparoscopic surgery. Our hypothesis was that patients think the surgeon Medicare fee schedule is higher than actuality. METHODS: Patients filled out an IRB exempted survey. The survey included a written description of laparoscopic gastric bypass, laparoscopic adjustable gastric band placement, laparoscopic cholecystectomy and an initial patient visit for 30 minutes. All participants were asked to give their thoughts of what Medicare currently reimburses for these procedures as well as what the payment should be. The survey also asked other questions about reimbursement related to Medicare. RESULTS: There were 96 participants in the investigation with 43% of patients not filling in reimbursements for at least one procedure. Most patients (88%) looked at their bills from physicians and insurance companies carefully. For each procedure, the mean reimbursements were approximately 10 times higher than the patient perception of both the amount Medicare currently pays and the amount Medicare should pay compared to the actual fee. For the initial patient visit, the patients overestimated the payment by 158% and thought the Medicare should pay 199% of the actual fee. Most of the patients (98%) thought Medicare should pay more for more difficult cases and 85% thought Medicare should pay more if the patient visits the surgeon more times during the global period. While 32% of the patients feel Medicare pay physicians well, 91% thought that Medicare should increase fees. CONCLUSION: Most of our patients overestimated what Medicare currently pays for some laparoscopic procedures. Surgeons need to do a better job in educating patients and the general public about the Medicare fee schedule.

Stimulation of human omental adipose tissue lipolysis by growth hormone plus dexamethasone.

Growth hormone [GH] administration results in a reduction in adiposity of humans that is attributed to stimulation of lipolysis. We examined the effect of direct addition of human GH, in both the absence and presence of dexamethasone [Dex], as well as that of interferon beta on lipolysis by omental adipose tissue explants from obese women incubated for 48h in primary culture. There was a significant stimulation of lipolysis by GH in the presence of Dex but not by Dex or GH alone. There was also a significant further stimulation by GH in the presence of Dex of hormone-sensitive lipase, perilipin, lipoprotein lipase and beta1 adrenergic receptor mRNA. We conclude that the direct lipolytic effect of GH is accompanied by an increase in HSL mRNA in the presence of DEX, but GH also increased the mRNAs for other proteins that could explain all or part of its lipolytic action.

Goal-directed laparoscopic training leads to better laparoscopic skill acquisition.

INTRODUCTION: Laparoscopic skills training outside the operating room is becoming the standard for educating surgical residents. Because of the restrictions on the work week, it is imperative for this training to be efficient. We hypothesized that goal-directed laparoscopic training (GDLT) would result in better skill acquisition than laparoscopic training without goals (LT). METHODS: Second-year general surgery residents participated in this study. Metrics were scores that incorporated time and errors. One group of residents (LT) went through a 10- week laparoscopic training course without goals; one group of residents (GDLT) was given goals to achieve during their course. Each group practiced for the same amount of time. The tasks were peg exercise, run the rope, pattern cutting, clip/cut vessel, extracorporeal knot tying, intracorporeal knot tying, and suturing device. Statistical analysis was performed via 2-tailed Mann-Whitney tests. RESULTS: There were 8 residents in the LT group and 7 residents in the GDLT. The GDLT group had statistically significant higher scores on 7 of the 8 tasks compared the LT group (P < .02 to P < .0001). The GDLT group performed better in the final task, suturing device, than the LT group, but this did not reach statistical significance (451 vs 414; P = .14). CONCLUSIONS: GDLT should be used by surgeons instead of LT. Future studies need to examine whether GDLT translates into a better operative technique and outcomes.

Comparison of two low-molecular-weight heparin dosing regimens for patients undergoing laparoscopic bariatric surgery.

BACKGROUND: Venous thromboembolic events (VTE) are a morbidity and mortality concern for patients undergoing laparoscopic bariatric surgery. Although VTE prophylaxis is recommended in bariatric surgery, data with regard to monitoring and appropriate dosing of low-molecular-weight heparin are limited. Enoxaparin prophylactic doses ranging from 30 to 60 mg every 12 h have been used for this population. The authors hypothesized that higher prophylactic enoxaparin doses (60 mg) would yield more appropriate heparin antifactor Xa (anti-Xa) concentrations than the 40-mg dosage for bariatric surgery patients. METHODS: Patients undergoing laparoscopic bariatric surgery by two surgeons during a 5-month period at one institution received enoxaprin 40 or 60 mg every 12 h. Anti-Xa levels were obtained 4 h after the first and third doses. Therapeutic levels were defined as 0.18 to 0.44 U/ml. Paired and unpaired t-tests and chi-square tests were used for statistical analysis as appropriate. RESULTS: The first-dose mean anti-Xa concentration was 0.173 U/ml in the 40-mg group and 0.261 U/ml in the 60-mg group (p < 0.005), compared with the third-dose mean anti-Xa levels of 0.21 and 0.43 U/ml, respectively (p < 0.001). After the third dose of enoxaparin, the percentage of patients with anti-Xa concentrations who remained subtherapeutic showed a statistically significant difference: 44% in the 40-mg group versus 0% in the 60-mg group (p = 0.02). However, no supratherapeutic anti-Xa concentrations were observed in the 40-mg group, whereas 57% of the third-dose levels in the 60-mg group were supratheraputic. The highest anti-Xa level was 0.54 U/ml, but none of the patients with this level experienced bleeding events. CONCLUSIONS: Enoxaparin 60-mg every 12 h was superior to a dosage of 40 mg every 12 h in achieving therapeutic anti-Xa concentrations and avoiding subtherapeutic anti-Xa levels. However, the 60-mg group had a number of supratherapeutic levels. Future studies evaluating the relationship of anti-Xa concentrations and outcomes with larger numbers of morbidly obese patients are needed.