Bariatric (metabolic) surgery and medical devices

Below is an excerpt from "Products, Technologies and Markets Worldwide for the Clinical Management of Obesity 2011-2019." (Report #S835.)


Bariatric surgery is the leading non-pharmaceutical treatment for obesity. In fact, to date, it is the only effective, proven treatment for morbid obesity. Another phrase to describe surgery for weight loss is starting to come into use: metabolic surgery. This phrase better indicates the complexity of the systems which are involved in regulating and producing hunger, cravings, digestion and obesity.
 
Gastric bypass surgery is currently considered the gold standard in the US for surgical treatment of obesity. Studies have shown that patients tend to experience 50-80% excess weight loss (EWL) over a two year period following surgery. In addition, gastric bypass offers sustainable weight loss, and has a better record in this regard than does gastric banding.
 
Weight regain is not unknown, however, and has been reported to be as high as 25-30%, depending on the type of procedure and the patient’s dedication to changing. Patients must follow significant, permanent diet and lifestyle modifications following surgery, which is one reason that patients are usually required to undergo psychiatric testing and counseling prior to having the surgery. If weight is regained, then factors such as psychiatric challenges, the patient’s degree of adherence to the new diet, and general health must all be reviewed. Once these have been dealt with, then surgical revision may be considered.
 
Bariatric surgery falls into one of three categories, depending upon the type of procedure: restrictive, malabsorptive or a combination of these. ‘Restrictive’ refers to restricting the size of the stomach, so that the patient feels full on less food. This may be achieved using gastric stapling, gastric banding or by surgically removing a large part of the stomach. ‘Malabsorptive’ surgery involves making significant surgical changes to the digestive tract by bypassing most of the stomach and intestines, thereby shortening the absorptive surface area of the bowel. Because so much absorptive area is lost, the patient must take vitamins and minerals for the rest of his or her life.
 
In the US and European Union, bariatric surgeons generally perform the following major procedures:
  • Gastric bypass, including a variation known as vertical banded gastroplasty (VBG); the latter is both malabsorptive and restrictive.
  • Roux-en-Y (vertical division)
  • Sleeve gastrectomy independent of biliopancreatic diversion.
  • Biliopancreatic diversion with duodenal switch (both malabsorptive and restrictive)
  • Gastric banding (restrictive)

These may be performed using either open surgery or laparoscopically, but are usually done via laparoscope. 

Aside from surgical procedures alone, the other major category of non-pharmaceutical treatment for obesity is in the use of medical devices spanning restrictive devices, artificial fullness devices, malabsorption devices, devices to control gastric emptying and appetite suppression devices.

 
Gastric banding has become one of the most popular bariatric procedures in the USA, Europe, Australia, and South America. A laparoscopic adjustable gastric band is a restrictive device implanted via bariatric surgery and designed for obese patients with a body mass index (BMI) of 40 or greater—or between 35–40 in cases of patients with certain comorbidities that are known to improve with weight loss, such as sleep apnea, diabetes, osteoarthritis, or metabolic syndrome, among others. Initial weight loss is slower than with Roux-en-Y, commonly on the order of 1-2 pounds per week.
 
Devices that are intended to cause a feeling of fullness, hence decreasing the amount of food consumed, include intragastric balloons and the EndoSphere device. EndoSphere is in stealth mode at this time; no further information about its device is being shared other than that it causes a feeling of fullness.
 
The intragastric balloon, as its name implies, is a balloon that is placed in the stomach, and then inflated by filling it with air, water or saline, depending upon the particular model. Insertion techniques vary. In general, the collapsed balloons, stiffened by a guide wire, are advanced into the stomach in a manner similar to the insertion of a nasogastric tube. Once in the stomach the balloon is endoscopically evaluated and inflated to varying volumes (ranging from 400–800cc), depending on the manufacturer and model. The filled balloon takes up space in the stomach; less space remains for food, so the patient feels full faster, stops eating sooner, and loses weight. Removal is performed by endoscopic deflation of the devices either by needle deflation through a re-penetrable valve, or needle puncture and removal with a basket or a snare. To date, there are no intragastric balloons approved for use in the US.
 
The striking hormonal alterations seen with gastric bypass surgery are causing researchers to reexamine what they know about the biological mechanisms which occur when the duodenum and proximal jejunum are bypassed. In particular, the improvement in insulin sensitivity and glucose metabolism seen with gastric bypass can occur immediately after surgery, well before any significant weight loss has occurred. Malabsorption devices, as the name implies, physically hinder the body’s full absorption of elements of ingested food by imitating a gastric bypass. These devices are intended for temporary placement and are reversible.
 
Another way to hinder absorption of food is to control the rate of emptying of the stomach by slowing it down. Slower emptying means a greater feeling of fullness, leading the patient to eat less. It may also cause changes in other metabolic hormonal processes. Both the TPS and the TERIS devices are in development, and are not forecast to enter the market before 2012. The Botox solution is also in early stages of investigation.
 
Devices intended to decrease the appetite generally begin to work when the individual begins to eat. Examples of these devices include MetaCure's Tantalus, EnteroMedics' Maestro system and Silhouette Medical’s nObese RF Ablation Device.