Abstract

Morbid obesity is a growing problem affecting millions of Americans. Bariatric surgery is an effective method to combat obesity in those who have failed diet and exercise attempts. Unfortunately, some patients do not experience satisfactory weight loss after bariatric surgery. We are currently trialing shortening of the common channel as a method for weight loss in patients who have previously undergone Roux-en-Y gastric bypass. Our aim is quantify the weight loss after shortening of the common channel to determine if it is a satisfactory method of further weight loss after Roux-en-Y gastric bypass. Between 2020-2021 we had 16 patients who underwent shortening of the common channel. Weight loss, body mass index (BMI) and excess weight loss (%EWL) were recorded at 3,6,9 and 12 months postoperatively. The mean weight prior to shortening of the common channel was 238 lbs ± 29. BMI prior to shortening of the common channel was 41 kg/m² ± 4. Patients in the study lost 14 lbs (n=10), 28 lbs (n=9), 40 lbs (n=6) and 57 lbs (n=4) at 3, 6, 9 and 12 months respectively. At 9 months and beyond, patients experienced an 11-point reduction in their BMI, from an average BMI of 41 kg/m² preoperatively to 29.5 ± 5.6 (n=8). After 9 months patients had a 75% reduction in excess weight. Currently many patients are still undergoing their routine follow up, as their procedures occurred less than a year ago. One patient unfortunately passed away due to consequences of malnutrition secondary to bariatric surgery. Another patient had to receive supplemental nutrition via tube feeds through the gastric remnant. Currently, shortening the common channel offers reasonable weight loss in patients who have unsatisfactory weight loss post gastric bypass but care should be taken as there is a high risk for malnutrition. Further follow-up is needed to continue to evaluate long-term weight loss in these patients and to monitor for malnutrition in subsequent years.

1. Introduction

Obesity is a life-threatening condition with serious comorbidities which affect millions of people around the world. The prevalence of adult obesity in the U.S. has now reached an all-time high of 42%, with morbid obesity increasing to 9.2% ¹. Bariatric surgery is an excellent option for morbidly obese patients, many of whom have failed multiple attempts at medically managed weight loss and exercise programs. Undergoing surgery for morbid obesity has been shown to have numerous health benefits, especially a reduction or elimination of several serious obesity comorbidities. It has also been shown that morbidly obese patients who undergo bariatric surgery have lower all-cause mortality at both the five- and ten-year mark when compared to those who did not have surgery ⁶. Bariatric surgery can resolve diabetes mellitus type II, reduce hypertension, and improve obstructive sleep apnea ^{8, 10, 11}.

Worldwide, the most common weight loss surgery is still the Roux-en-Y gastric bypass which makes up about 45% of weight loss procedures, followed by sleeve gastrectomy at 37% ². In the U.S. during the year 2019, the Roux-En-Y surgery made up about 17.8% of bariatric surgeries ⁷. The SLEEVEPASS randomized clinical trial found that 7 years post-op, the gastric bypass procedure resulted in greater weight loss than the gastric sleeve ⁹. However, for roughly 15% of patients that undergo the gastric bypass, they experience unsatisfactory weight loss which is defined as excess weight loss < 50% or a body mass index (BMI) > 35 kg/m^{2 4, 12}. The gastric bypass also has a revision rate of 4.5% ⁴. With the laparoscopic gastric bypass as one of the most successful operations for losing weight, a new strategy must be formulated for these refractory patients. While stricter dieting changes and GLP-1 agonists have shown some improvement in post-surgery weight loss, shortening the common channel is proving to be an effective method to increase weight loss post-gastric bypass ^{13, 14}. By shortening the common channel, the absorptive surface area of the digestive system further decreases, resulting in increased malabsorption and weight loss for patients with unsatisfactory weight loss.

2. Methods

In our practice, we have performed shortening of the common channel to help increase weight loss in patients who have had unsatisfactory weight loss after gastric bypass. We performed a retrospective study to identify the efficacy of shortening of the common channel. Patients which we deemed candidates for shortening of the common channel were patients who had previously undergone previous Roux-en-Y gastric bypass and had not achieved satisfactory weight loss after one year or had lost weight and subsequently regained weight. Unsatisfactory weight loss being <50 %EWL or BMI > 35 kg/m².

In our standard gastric bypass, our biliopancreatic limb measures approximately 100 cm distal to the ligament of Treitz and our roux limb measures 150 cm. We do not measure our common channel in our gastric bypassess. When performing shortening of the common channel, we begin the procedure by identifying the patients anatomy. The gastrojejunal anastomosis is found and the roux limb is run down to the jejunojejunostomy and divided off the common channel. The length of the roux limb is measured prior to transection. We then proceed to the right lower quadrant and identify the terminal ileum at the ileocecal valve and run the bowel proximally. We aim for a total alimentary limb length of approximately 300 cm. In most patients the roux limb is approximately 150 cm in length, in this case we run the bowel proximally 150 cm from the ileocecal valve and perform our new jejunojejunostomy at this location. This gives us a total alimentary length of 300 cm.

Between 2020 and 2021, we identified 16 patients who had previously undergone gastric bypass surgery and subsequently undergone shortening of the common channel due to inadequate weight loss. In all patients, the length of the roux limb and common channel measured to an alimentary limb length of 300 cm. Of these patients 16 patients, 6 were lost to follow-up before three months. Average starting weight for patients who underwent shortening of the common channel was 239 lbs ± 29 lbs and preoperative BMI was 40.9 kg/m² ± 4. At 12 months the average patient weight was 161 lbs (n=4) (Figure 1). At 3 month follow up, the average weight loss was 14 lbs (n=10). At 6 months, the weight loss average was 28 lbs (n=9). At 9 months 40 lbs (n=6) and at 1 year 57 lbs (n=4) (Figure 2). The average BMI at 9-12 months was 29.5 kg/m² ± 5.6 (n=8) with an average %EWL being 75% after 9 months. Many of the patients had surgery done within the past year, thus the low sample size for weight loss at 9 months and beyond. These patients are still conducting follow ups at regularly scheduled intervals.

The feared long-term complication with bariatric procedures is protein calorie malnutrition. One patient who experienced severe medically-refractory depression, subsequently suffered malnutrition secondary to noncompliance with diet and vitamin recommendations and unfortunately passed away from unknown causes. This patient had a preoperative BMI of 47.5 and a 9-month post procedure BMI of 36.9 kg/m². The patient had a total weight loss of 50 lbs and 47% EWL prior to their passing. The other patient had a preoperative BMI of 36.8 and a 12-month post procedure BMI of 22.3 kg/m². The total weight loss for this patient was 53 lbs and 123% EWL. This patient suffered from weakness, fatigue, hair loss and lymphedema. This patient also was non-compliant, possibly to a language barrier. Both procedures were done in the standard fashion with a total alimentary limb length of 300 cm. The second patient was treated with duodenal switch-appropriate vitamin samples and enteric tube feeds from the gastric remnant. They are now improving dramatically without tube feeds and tube will be removed soon.

3. Discussion

Failure of adequate weight loss or weight regain is a known problem after Roux-en-Y gastric bypass, with some studies showing failure rates as high as 15% ⁴. Literature outlining methods to aid patients who have failed to lose weight after the gastric bypass is limited. More restrictive dieting or medical management with GLP-1 agonists have been trialed in some patients with some success ⁵.

Shortening of the common channel in our patient population has shown exceptional weight loss at the one-year mark thus far. Shortening of the common channel functions by decreasing the absorptive capacity of the bowel by reducing functional length. However, with this treatment there is a higher risk of malnutrition due to the further shortening of the total alimentary limb length. Of our 16 patients, two patients have suffered from malnutrition secondary to shortening of their common channel and non-compliance with diet and vitamin regimens. The procedure appears to be reasonable for patients whose post bypass weight is much higher than their ideal body weight. It should be used with caution in those who are close to their ideal body weight due to the risk of postoperative malnutrition. For patients closer to their ideal body weight, medical management with GLP-1 agonists is likely a feasible and safer option to help lose excess weight with less side effects than revision surgery.

Our study was also limited by the small size of our cohort and the short length of follow up due to procedures being performed within the last two years. Currently from the 9 months to one-year mark, patients have continued to lose weight with an average weight loss of 17 lbs in that time frame. Further follow-up is needed to identify the total expected weight loss from shortening of the common channel as well as continued observation for development of malnutrition. We have no conflicts of interest to disclose regarding our study.

4. Conclusion

Shortening of the common channel is a reasonable adjunct to increase weight loss in post Roux-en-Y gastric bypass patients who have failed to achieve or maintain satisfactory weight loss after initial surgery. Currently our data shows satisfactory weight loss at the one-year mark with EWL of 75%. We did observe a 12.5% risk of postoperative malnutrition within one year of revision surgery secondary to patient non-compliance. Shortening of the common channel should be used with caution in patients at risk for non-compliance. Further follow up beyond one year is needed to assess the total expected weight loss after shortening of the common channel and the overall risk of malnutrition and further follow-up will be needed.

Acknowledgements

Sofia Fabrega, MS-1 for performing statistical analysis for this paper.

References