Brief History and Summary of Bariatric Surgery

Chapter 4.

BILIOPANCREATIC DIVERSION

Scopinaro first performed the biliopancreatic diversion (BPD) which was designed to be a safer malabsorptive alternative to the JIB. This operation induces controlled malabsorption without many of the potential side effects caused by bacterial overgrowth associated with the JIB. The m alabsorptive operations differ from the RYGBP and the gastric banding, which work mainly through restriction.

Malabsorption is defined by the incomplete uptake of calories and nutrients and occurs via two mechanisms. First, the bile and pancreatic fluids released into the duodenum to digest food and break down fats, carbohydrates and proteins are diverted away from ingested food – hence the name, biliopancreatic diversion. The digestive enzymes eventually join the ingested food – but at a point in the distal small intestine (ileum) where there is much less chance for complete breakdown and absorption. When food is in the diverted small intestine it is not absorbed as well because of the lack of enzymes to break down the larger fat, protein and carbohydrate molecules into their smaller building blocks, the actual particles absorbed. Because of the particular digestive aids necessary to absorb fats (bile and lipase are crucial), fat calorie malabsorption predominates. Unfortunately, undigested fats cause gas and loose, foul-smelling bowel movements, called steatorrhea. The second mechanism through which malabsorption occurs is by decreasing the amount of small intestine through which the ingested food passes. With less surface area of intestine with which food is in contact, less nutrients can be absorbed.

Unlike the RYGBP where no stomach is removed (only bypassed), the BPD involves the removal of 70% of the stomach. This procedure is done to decrease the amount of acid produced by the remaining stomach. Gastrin, a hormone produced by G-cells in the antrum, is responsible for stimulating the upper stomach to produce acid. Of note, the portion of the remaining upper stomach is far larger than the small “pouch” created for the RYGBP. This allows patients to eat larger volumes than after a restrictive operation before feeling full (satiety). After entering the upper stomach, food passes through a newly created connection (anastomosis) into the small intestine (alimentary limb). This anatomy is very similar in principle to the standard RYGBP, except that the length of the intestine from the stomach to the colon is much shorter – promoting malabsorption. The bile and pancreatic secretions pass through the bypassed biliopancreatic channel and connect with the alimentary channel (where the food travels) 50-100 cm from the colon. Some of these secretions are reabsorbed in this channel prior to meeting the alimentary tract. The part of the intestines where bile and pancreatic fluids (from the biliopancreatic channel) and food (from the alimentary channel) mix is called the common channel. Surgeons use various formulas to determine the appropriate length of the alimentary channel and the common channel.

The amount of excess weight loss after the BPD has been reported to be around 70 percent – with weight loss in some patients persisting up to 18 years. However, like all weight loss data, this percentage of excess weight lost varies depending on the length of follow-up, the quality of follow-up, the country where the procedure was performed, the surgeon, and the initial weight of the patient. Being a malabsorption operation, however, the BPD requires life-long medical follow-up.

DUODENAL SWITCH

The duodenal switch (DS) is a modification of the BPD designed to prevent ulcers, increase the amount of gastric restriction, minimize the incidence of dumping syndrome, and reduce the severity of protein-calorie malnutrition. However, the dumping syndrome is also believed by many to be a benefit, rather than a detriment, in that it helps patients avoid eating sugary and high fat foods which would adversely affect weight loss. The DS was first reported by Dr. Doug Hess in 1986.

The DS works through an element of gastric restriction as well as malabsorption. The stomach is fashioned into a small tube, preserving the pylorus, transecting the duodenum and connecting the intestine to the duodenum above where digestive juices enter the intestine. Compared to the BPD, the DS leaves a much smaller stomach that creates a feeling of restriction much like that of a RYGBP. Anatomically, the main difference between the DS and the BPD is the shape of the stomach – the malabsorptive component is essentially identical to that of the BPD. Instead of cutting the stomach horizontally and removing the lower half (such as with the BPD), the DS cuts the stomach vertically and leaves a tube of stomach that empties into a very short (2-4 cm) segment of duodenum.

The duodenum is tolerant of stomach acid and therefore is much more resistant to ulceration compared to the small intestine. Removing part of the stomach also decreases the amount of acid present. Whereas the BPD involves an anastomosis (connection) between the stomach and the intestine, the DS involves an anastomosis between the duodenum and the intestine. The duodenum is cut about 2-4 cm from the stomach (measured from the pyloric valve). The intestine is sewn to the end of the duodenum which remains in continuity with the stomach. The other side of the duodenum will carry all the bile and pancreatic secretions. A theoretical (but clinically unproven) benefit of the DS is an improvement in absorption of iron and calcium in comparison to the BPD. The disadvantage of transecting the duodenum is the large number of vital structures immediately adjacent to the duodenum. Several large blood vessels and the major bile duct are located here. Injury to these structures can be life-threatening.

These procedures have some of the highest reported weight loss in long-term studies, but also have the highest rate of nutritional complications compared to the RYGBP and the purely restrictive procedures. These operations are some of the most complex in bariatric surgery. However, as with most studies of weight loss surgery, there is wide variability in long-term results between different centers. Only multi-center comparative studies can establish definitively the true differences between all these operations.

Some patients and surgeons believe that the DS is a superior operation to the RYGBP and BPD because of the lack of a “dumping syndrome”, described above. The DS and BPD have their own particular side effects. After a meal that is high in fat, people can experience foul smelling gas and diarrhea.

Advantages of BPD and DS:

Increased amount of food intake compared to the bypass and band
Less food intolerance
Possibly greater long-term weight loss
More rapid weight loss compared with gastric banding procedures

Complications of BPD and DS:

Diarrhea and foul smelling gas, with an average of 3-4 loose bowel movements a day
Malabsorption of fat soluble vitamins (Vitamins A, D, E, and K)
Vitamin A deficiency, which causes night blindness
Vitamin D deficiency, which causes osteoporosis
Iron deficiency –a similar incidence with the RYGBP
Protein-calorie malnutrition, which might require a second operation to lengthen the common channel
Ulcers (less frequent with DS)
Dumping syndrome (less frequent with DS)

Summary

Both the BPD and the DS can be performed laparoscopically. However, these operations are more demanding technically than the RYGBP and should only be performed in the most experienced hands. Long-term follow up and daily vitamin supplements are crucial to the success of these operations. Life-long monitoring is necessary to prevent nutritional and mineral deficiencies – just as with the RYGBP.

REFERENCES

Biliopancreatic diversion and duodenal switch

Scopinaro, N., Gianetta, E, et al. Biliopancreatic diversion for obesity at eighteen years. Surgery 1996;119:261-8.

Hess DS, Hess DW. Biliopancreatic diversion with a duodenal switch. Obes Surg 1998;8:267-82.

Marceau P, Hould FS, Simard S, et al. Biliopancreatic diversion with duodenal switch. World J Surg. 1998;22:947-54.

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TABLE OF CONTENTS

• Chapter 1. INTRODUCTION

• Chapter 2. JEJUNOILEAL BYPASS

• Chapter 3. GASTRIC BYPASS & LAPAROSCOPIC GASTRIC BYPASS

• Chapter 4. BILIOPANCREATIC DIVERSION DUODENAL SWITCH

• Chapter 5. GASTROPLASTY

• Chapter 6. GASTRIC BANDING & LAPAROSCOPIC ADJUSTABLE GASTRIC BANDING

• Chapter 7. ON THE HORIZON & SUMMARY

• References

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