Article: Bariatrics

Bariatrics is the branch of medicine that deals with the causes, prevention, and treatment of obesity^[1]. The term bariatrics was created around 1965 ^{[citation needed]}, from the Greek root baro ("weight," as in barometer) and suffix -iatrics ("a branch of medicine," as in pediatrics). Besides the pharmacotherapy of obesity, it is concerned with obesity surgery.

Overweight and obesity are rising medical problems of pandemic proportions^[2][3]. There are many detrimental health effects of obesity^[4]: heart disease, diabetes, many types of cancer, asthma, obstructive sleep apnea, chronic musculoskeletal problems, etc. There is also a clear effect of obesity on mortality, though this is not so clear for overweight ^[5].

Diagnosis

Although not a direct measure of body fat, the Body Mass Index is widely adopted and promoted as a marker for excess body weight.^[6]. However, it is not flawless: a very muscular person may be assessed as obese, and an elderly person with low body weight but high body fat (this can happen due to low muscle mass and bone density) may be assessed as healthy. Other markers for the evaluation of obesity include waist circumference (associated with central obesity), and a patient's risk factors for diseases and conditions associated with obesity^[7]. Besides these indirect methods, body fat can also be measured directly.

Treatment

Although diet, exercise, behavior therapy and anti-obesity drugs are first-line treatment^[7], medical therapy for severe obesity has limited short-term success and almost nonexistent long-term success.^[8]. Therefore, obesity surgery (or bariatric surgery) has been a popular treatment in the war against obesity. Weight loss surgery generally results in greater weight loss than conventional treatment, and leads to improvements in quality of life and obesity related diseases such as hypertension and diabetes^[9].

Before someone can become eligible for bariatric surgery, certain criteria must be met.^[8] The basic criteria are^[10]:

• a body mass index (BMI) of 40 or more —about 45 kg (100 pounds) overweight for men and 35 kg (80 pounds) for women
• a BMI between 35 and 39.9 and a serious obesity-related health problem such as type 2 diabetes, heart disease, or severe sleep apnea (when breathing stops for short periods during sleep)
• an understanding of the operation and the lifestyle changes you will need to make.

The prevalence of extreme obesity (body mass index > or = 40 kg/m²) in the United States in 2003-2004 was 2.8% in men and 6.9% in women.^[11] This suggests millions of people are in the weight range for potential therapy with bariatric surgery. Laparoscopic surgery has become an important addition to this field of surgery, and demand soars, amidst scientific and ethical questions.^[12]

Surgical procedures

There are a number of surgical options available to treat obesity, each with their advantages and pitfalls. In general, weight reduction can be accomplished, but one must consider operative risk (including mortality) and side effects. Usually, these procedures can be carried out safely^[13]. Procedures can be grouped in three main categories (although this is somewhat artificial)^[14]:

• predominantly malabsorptive procedures: although also reducing stomach size, these operations are based mainly on malabsorption.
  • Biliopancreatic Diversion (Scopinaro procedure)
• predominantly restrictive procedures: this kind of surgery primarily reduces stomach size
  • Vertical Banded Gastroplasty (Mason procedure, stomach stapling)
  • Adjustable gastric band (or "Lap Band")
  • Sleeve gastrectomy
• Mixed procedures: applying both techniques simultaneously
  • gastric bypass surgery, like Roux-en-Y gastric bypass
  • Sleeve Gastrectomy with Duodenal Switch

Biliopancreatic diversion

Diagram of a biliopancreatic diversion.

This complex operation is also known as biliopancreatic diversion (BPD), or Scopinaro procedure. Part of the stomach is resected, creating a smaller stomach (this is the restrictive part). The distal part of the small intestine is then connected to the pouch, bypassing the duodenum and jejunum. This results in severe malabsorption and nutritional deficiency.

The malabsorptive element of BPD is so potent that those who undergo the procedure must take vitamin and mineral supplements above and beyond that of the normal population. Those that do not run the risk of deficiency diseases such as anemia and osteoporosis.

Because gallstones are a common complication of rapid weight loss following any type of weight loss surgery, some surgeons may remove the gall bladder as a preventative measure during BPD. Others prefer to prescribe medication to reduce the risk of post-operative gallstones.

Far fewer surgeons perform BPD compared to other weight loss surgeries, in part because of the need for long-term nutritional follow-up and monitoring of BPD patients.

Vertical Banded Gastroplasty and Adjustable Gastric Banding

Diagram of a vertical banded gastroplasty.

Diagram of an adjustable gastric banding.

In the vertical banded gastroplasty, a part of the stomach is stapled to create a smaller pre-stomach pouch, which serves as the new stomach.

The same effect can be created using a silicone band, which can be adjusted by the patient. This operation can be performed laparoscopically, and is commonly referred to as a "lap band." The first gastric band was patented in 1985 by Obtech Medical of Sweden (now owned by J&J/Ethicon) and is known as the Swedish Adjustable Gastric Band (SAGB). An American company, INAMED Health, later designed the BioEnterics ® LAP-BAND ® Adjustable Gastric Banding System. The LAP-BAND® System was introduced in Europe in 1993. Neither of these bands were initially designed for use with keyhole surgery. The LAP-BAND System received Food and Drug Administration (FDA) approval for use in the United States in June 2001. In 2000, the first lower pressure, wider, one-piece adjustable gastric band called the MIDband ® was placed in Lyon France Medical Innovation Development[1]. Unlike many of the early bands this was designed specifically for laparoscopic insertion. It has swiftly become one of the leading bands placed in France. There are now many band manufacturers (approx 7-8 in total).

Gastric Bypass Surgery

Diagram of a Roux-en-Y gastric bypass.

The most common form of gastric bypass surgery is Roux-en-Y gastric bypass surgery. Here, a small stomach pouch is created with a stapler device, and connected to the distal small intestine. The upper part of the small intestine is then reattached in a Y-shaped configuration.

The gastric bypass is the most commonly performed operation for weight loss in the United States. In the U.S, approximately 140,000 gastric bypass procedures were performed in 2005, an amount dwarfing the number of Lap-Band®, duodenal switch and vertical banded gastroplasty procedures done. Furthermore, since the gastric bypass has been performed for almost 50 years, surgeons have become very comfortable with the understanding of the risks and benefits of the procedure. By sheer volume of cases combined with the volume of scientific research, the gastric bypass has become the "gold standard" operation for weight loss in the U.S. An emerging factor in the success of gastric bypass surgery is following an established gastric bypass diet after surgery

Sleeve gastrectomy with duodenal switch

Diagram of a sleeve gastrectomy with duodenal switch.

A variation of the biliopancreatic diversion includes a duodenal switch. The part of the stomach along it's greater curve is resected. The stomach is then disconnected from the duodenum and connected to the distal part of the small intestine. The duodenum and the upper part of the small intestine are reattached to the rest at about 75-100 cm from the colon.

Anti-obesity drugs

Examples of anti-obesity drugs include orlistat and reductil, and the withdrawn Fen-phen.

References

1. ^ "Bariatrics." The American Heritage Dictionary of the English Language.4th ed. Houghton, 2000. Bartleby.com. 2005. 14 Feb. 2006 http://www.bartleby.com/61/84/B0078400.html>.
2. ^ Reynolds K, He J.Epidemiology of the metabolic syndrome.Am J Med Sci 2005;330:273-9. PMID 16355011
3. ^ Hedley AA, Ogden CL, Johnson CL, et al. 2004. Prevalence of overweight and obesity among US children, adolescents, and adults, 1999–2002. JAMA ; 291: 2847–50. PMID 15199035
4. ^ WHO factsheet on obesity
5. ^ Flegal KM, Graubard BI, Williamson DF, Gail MH. Excess deaths associated with underweight, overweight, and obesity. JAMA 2005; 293: 1861-7.
6. ^ Obesity: preventing and managing the global epidemic. Geneva, World Health Organization (WHO Technical Report Series, No. 894).
7. ^ ^a b Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, The Evidence Report. NIH Publication NO. 98-4083, september 1998. NATIONAL INSTITUTES OF HEALTH National Heart, Lung, and Blood Institute in cooperation with The National Institute of Diabetes and Digestive and Kidney Diseases.
8. ^ ^a b Gastrointestinal surgery for severe obesity: National Institutes of Health Consensus Development Conference Statement. Am J Clin Nutr 1992;55(S2):615S-619S. PMID 1733140
9. ^ Colquitt J, Clegg A, Sidhu M, Royle P. Surgery for morbid obesity. Cochrane Database Syst Rev 2003; 2: CD003641. PMID 12804481
10. ^ Gastrointestinal surgery for severe obesity. U.S. Department of Health and Human Services, National Institutes of Health. NIH Publication No. 04-4006, December 2004.
11. ^ Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999-2004. JAMA 2006; 295:1549-55. PMID 16595758
12. ^ Mitka M. Surgery for obesity: demand soars amid scientific, ethical questions. JAMA 2003; 289: 1761-2.
13. ^ Nguyen NT et. al. Result of a national audit of bariatric surgery performed at academic centers: a 2004 University HealthSystem Consortium Benchmarking Project. Arch Surg 2006; 141: 445-9. PMID 16702515
14. ^ Abell TL, Minocha A. Gastrointestinal complications of bariatric surgery: diagnosis and therapy. Am J Med Sci 2006;331: 214-8.

External links

• MedLinePlus Portal on Weight Loss Surgery
• American Society for Bariatric Surgery