Reply to Gastric Emptying After Sleeve Gastrectomy (OBSU-D-11-00201)

Abstract

Dear Editor, We thank Melissas and Daskalakis for their interest in our study “Gastric emptying and postprandial PYY response after biliopancreatic diversion with duodenal switch”. We share the view that methodological differences in gastric emptying studies are a problem. The three listed studies [1–3], as well as new MRI-based work [4], have all used different meals with different caloric content, making comparisons very challenging. Moreover, these studies examine gastric emptying after the gastric sleeve procedure. The procedure studied in our paper [5], biliopancreatic diversion with duodenal switch (BPD-DS), is different to gastric sleeve in several respects, which is important when discussing results. First, the gastric tube empties directly into the proximal ileum, in contrast to the maintained passage into the untouched duodenum after sleeve gastrectomy. Second, the vagal innervation of the pylorus is most likely more affected by BPD-DS as compared to gastric sleeve since the proximal duodenum is circumferentially dissected and transected in BPD-DS. We also agree that gastric emptying is influenced by age, gender, physical activity levels, meal size and energy density among other factors which is why we state that interpreting our finding is a challenge [5]. We speculate that the difference in postoperative anatomy (and thus neurohormonal response to a meal) could explain our finding of a short median half-time (28 min) in our 20 studied BPD-DS patients versus 38–62 min in the gastric sleeve studies. We do not think, however, that this comparison should be made to strongly because of the differences between the operations discussed above. We present gastric emptying data after BPD-DS. We had to use different test meals for the gastric emptying and PYY studies. This was not ideal. Identical conditions in a large, homogenous group (minimal spread in age and BMI) in patients with the same gender, having repeated examinations, would be perfect for research. However, this is often not possible in clinical studies. For the scintigraphic studies, we used a quarter of a standardized meal developed after a national, multicentre study [6], since we wanted to be sure that the whole meal could be accommodated in the gastric remnant (which can be as small as 88 ml after BPD-DS [7]) before the first scan was taken. A standardized and uniform test procedure, adapted for the post-bariatric surgery setting would be ideal for our future joint understanding of this field.