Although not specifically about alimentary limb length, this study seems to show that it makes a difference, especially in patients where bmi >60:
http://www.ncbi.nlm.nih.gov/pubmed/18065296
Abstract
BACKGROUND:
It is commonly believed that weight loss after biliopancreatic diversion/duodenal switch is inversely related to the length of the alimentary limb and the common channel. However, the effect of the biliopancreatic limb length (BPL) on weight loss has received little attention.
METHODS:
A total of 1001 patients after biliopancreatic diversion/duodenal switch (209 men and 792 women, mean age 42 +/- 10 yr, mean body mass index [BMI] 52 +/- 9 kg/m(2)) were divided into 2 groups according to the ratio of the BPL to the total small bowel length (SBL): a BPL < or =45% of the SBL versus a BPL >45% of the SBL. The nutritional parameters and percentage of excess weight loss were compared between the 2 groups.
RESULTS:
In patients with a BMI of < or =60 kg/m(2), the percentage of excess weight loss at 1 year postoperatively was 66.8% for those with a BPL < or =45% of the SBL and 69.3% for those with a BPL >45% of the SBL (P = NS). At 2 years, the corresponding percentages were 73.7% and 79.5% (P = NS) and, at 3 years, were 73.4% and 75.2% (P = NS). In patients with a BMI >60 kg/m(2), the corresponding percentages of excess weight loss was 56.8% versus 61.4% (P = .07) at 1 year, 62.2% versus 77.5% (P = .04) at 2 years, and 59.8% versus 77.5% at 3 years (P = .05).
CONCLUSION:
The results of our study have shown that amount of weight lost after biliopancreatic diversion/duodenal switch is directly related to the proportion of small bowel bypassed in patients with a BMI >60 kg/m(2). Also, the effect increased with the duration of follow-up. In less heavy patients, the BPL/SBL ratio had a minimal effect on long-term weight loss and a more pronounced effect on nutritional parameters.
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