BPD, DS, ERNY Confusion

I've noticed a lot of posts recently comparing and confusing ERNY revision procedures with BPD revision procedures, a component of the DS. Some people are under the impression that a Bilio-Pancreatic Diversion (BPD) is the same as an ERNY.
 
The summary statement: A BPD procedure - with or without a DS - is absolutely NOT the same thing as an ERNY.

From reading some of the posts here on OH, it seems that this confusion arises from the impression that the small intestine acts essentially the same along its entire length. In other words, that food, calories, and nutrients are absorbed the same way no matter where in the small intestine the food happens to be passing at the time. In fact, different parts of the intestine handle nutrients in different ways. Different parts of the intestine will produce different hormones and metabolic signals in response to food passing through it. The chief example of this is the "neuro-endocrine brake" effect, the main metabolic effect of BPD/DS. Food passing through the upstream portion of the intestine fosters the deposition of fat within the body, where the same food passing through the downstream portion of the intestine has just the opposite effect. Moving this downstream intestine further upstream - as is done in BPD/DS - creates the "neuro-endocrine brake" effect. Our understanding of this effect dates back to the original work on "Ileal Transposition" dating back to the 1980's.

In an ERNY, no such re-arrangement of the downstream intestine occurs. The upstream intestine is simply moved further downstream; the upstream intestins remains attached to the stomach pouch. The total length of intestine is reduced - theoretically reducing absorption - but no increased metabolic effect occurs (in fact, it should - at least in theory - decrease the neuro-endocrine effect).

It appears that some of this confusion arose from posts discussing revision from RNY to DS. I am a great advocate of the DS, and it constitutes the bulk of my practice. It is the most metabolically active and most durabl procedure available for weight loss and reduction of co-morbidities. My goal when evaluating patients for revision from failed RNY is to get them to the endpoints of a DS procedure. Those three endpoints are restriction, malabsorption, and metabolic effect. The malabsorption and metabolic effect of a DS can only be accomplished by the Bilio-Pancreatic Diversion portion of the DS. Many patients, though, are already eating through their RNY pouches like a DS patient should. In these select patients, no further work on the stomach is necessary to get them to a DS lifestyle, in my opinion. For patients with dysfunctional RNY pouches, however, conversion to a full DS - or at least a Vertical Sleeve Gastrectomy - is necessary to get them to a more functional state. What is important is that, in the end, the patient have the proper combination of malabsorption, metabolic effect, and restriction, whether or not that restiction involves converting the RNY pouch to a Sleeve or not.

John D Husted, MD

Thank you very much Dr. Husted for clearing this up..so as I understand it, a revision from a RNY to DS can also be accomplished by leaving the pouch in tact if the pouch has a properly functioning restriction, if the pouch has lost the restriction function then it is necessary to get the pouch reconstructed to a sleeve. And that, in the revision from RNY to DS if my pouch is ok I am able to get the BPD portion of the DS which will allow me to reach the successful endpoint of restriction, malabsorption AND metabolic effect ; which the ERNY does not allow/offer the metabolic effectiveness. So the revision RNY to BPD/DS can be as effective as the full RNY toDS ?

Thanks for the post Dr. Husted.

I'll still a bit confused though can you answer these questions?.

1. How is the switch part of the BPD done while leaving the pouch intact? 

2. What happens to the blind or remnant stomach?

3. Can you use the Hess method to determine the Biliary Limb, Alimentary Limb and Common Channel?

4. Doesn't leaving the duodenum bypassed cause a more Iron and B12 malabsorption? It's already a problem for RNY and DS patients; seems like this would make that much worse. 

I understand the benefit of the "neuro-endocrine brake"; I just don't understand how you accomplish this when leaving the pouch and remnant stomach intact. 

Thanks again,

Kerry

The bypassed remnant stomach remains where it is, and the duodenum is left intact. The outlet of the old roux pouch continues to act as the stomach outlet.

The neuro-endocrine brake effect is a function of what happens in the intestine, not what happens in the stomach. The limb lengths are determined the same way a DS procedure.

This is not a revision for everybody, but for those patients who, through the test of time, have already shown that they do not have the effects of a RNY that would make them prone to malnutrition or other deficiencies after revision. For patients who have the typical RNY issues of protein intolerance, recurrent ulcer disease, and the like, conversion to a full DS is indicated.

John D Husted, MD

This question comes up often on the DS board because so many surgeons are doing ERNY's anymore.  I'm saving it to bring up later for the next person who asks.  I'm so glad to see you're still poking around .

Thank you for clearing this up, Dr. Husted.  I now have a much better understanding of how this works, not only from a revision standpoint, but in explanation of the metabolic effect.