436 - Bariatric Surgery and Kidney-Related Outcomes

bariatric surgery, it is increasingly important to under- stand the potential bene fi ts and risks of bariatric surgery in regard to kidney function and other outcomes. Overview of Bariatric Surgery Types Contemporary bariatric surgery techniques are very effective in achieving sustained weight loss, with total weight loss averaging 20% to 35% of total body weight. 12,13 Several surgical procedures to promote weight loss have been developed over the past few de- cades. These procedures vary in terms of the amount of gastric surface area restriction, intended nutrient malab- sorption, effects on gastrointestinal hormones, weight loss outcomes, and risk of complications ( Table 1 ). 14 Initial efforts in bariatric surgery started in the 1970s with the jejunoileal bypass, which was a purely malabsorptive procedure, bypassing most of the small intestine. 15 The jejunoileal bypass has since been abandoned due to the high rate of complications, which included de fi ciency of fat-soluble vitamins, bacterial overgrowth, calcium oxa- late nephrolithiasis, and kidney and liver failure. Currently, the most common bariatric procedures performed worldwide are laparoscopic Roux-en-Y gastric bypass (RYGB) and laparoscopic vertical sleeve gastrectomy (LSG). 16,17 The RYGB surgery involves both malabsorption and restriction. First, the stomach is divided into an upper stomach pouch (15 � 30 ml) and a lower gastric remnant ( Figure 2 ). The stomach pouch is then anastomosed to the mid-jejunum, and a jejuno- jejunal anastomosis is created to reconnect the bil- iopancreatic limb and the gastric remnant, thereby allowing gastric, pancreatic, and biliary secretions to mix with food in the jejuno-jejunal anastomosis. 14 LSG is a restrictive surgery that involves the removal of 70% to 80% of the lateral stomach. Due to its success in achieving weight loss and perhaps better safety pro fi le compared to RYGB, LSG has become more common in the past few years and has eclipsed RYGB in the United States ( Figure 3 ). 18 However, some patients who un- dergo LSG may require subsequent conversion to RYGB or duodenal switch surgery, in which bil- iopancreatic secretions are diverted from the food until the last portion of the small bowel to increase malab- sorption. Reported reasons for conversion of LSG to RYGB or duodenal switch surgery include weight regain and intractable acid re fl ux. 19 Laparoscopic adjustable gastric banding (LAGB) is another purely restrictive procedure that involves the insertion of an adjustable ring immediately below the gastroesophageal junction on the proximal stomach. Due to lower success in achieving weight loss and high risk of reoperation, LAGB has fallen out of favor during the past few years and is now much less commonly performed than RYGB or LSG. All 3 procedures are Figure 1. Trends* in class I, II, and III obesity over time in the US adult chronic kidney disease (CKD) population (National Health and Nutrition Examination Survey [NHANES] 1999 � 2014). * P values for linear trends over time # 0.01 for body mass index (BMI) $ 30, BMI $ 35, and BMI $ 40 kg/m 2 . Table 1. Comparison of the most common surgical procedures for weight loss RYGB LSG LAGB Weight loss Highest Moderate Lowest Gastric emptying [ or Y [ No change Plasma GLP-1 levels [ [ No change Plasma PYY levels [ [ No change Plasma ghrelin levels Variable [ Y Plasma leptin levels Y Y Y Plasma bile acid levels [ [ No change Fat malabsorption/fat-soluble vitamin de fi ciency [ No change No change Nephrolithiasis risk [ No change No change Diabetes remission Highest Moderate Lowest Short-term complications Higher Lower Lower Need for reoperation Lower Lower Higher GLP-1, glucagon-like peptide-1; LAGB, laparoscopic-assisted gastric banding; LSG, laparoscopic sleeve gastrectomy; PYY, peptide YY; RYGB, Roux-en-y gastric bypass. Adapted from previously published literature. 14,74,75 MINI SYMPOSIUM ON KIDNEY DISEASE AND OBESITY AR Chang et al.: Bariatric Surgery and Kidney-Related Outcomes 262 Kidney International Reports (2017) 2, 261 – 270 | The Surgical Technologist | APRIL 2020 160