Effect of intestinal tapering and lengthening on intestinal structure and function

Risk factors and outcomes of tapering surgery for small intestinal dilatation in pediatric short bowel syndrome

BACKGROUND

In remains unclear why in some short bowel syndrome (SBS) patients, the remaining small bowel (SB) dilates excessively leading to requirement of tapering surgery.

METHODS

Among SBS children, we retrospectively analyzed risk factors for tapering surgery with logistic regression and compared the outcome of operated patients (n=16) to those managed conservatively (n=44) with Cox proportional hazards regression.

RESULTS

SBS was caused by necrotizing enterocolitis (NEC) (n=31), SB atresia (SBA) (n=13), midgut volvulus (n=12), or gastroschisis (n=4). Patients with spontaneous symptomatic SB dilatation unable to wean parenteral nutrition (PN) underwent tapering surgery at median age of 1.04 (interquartile range 0.70-3.27) years. Missing ICV was related to an 8-fold (p=0.003) increased risk while SBA diagnosis was related to a 13-fold risk of tapering surgery (p<0.001). Increasing SB length and NEC diagnosis were protective of tapering (p=0.027-0.004). Of operated patients, 75% reached enteral autonomy during follow-up and their postoperative adjusted PN weaning rate was similar to nonoperated children (p=0.842).

CONCLUSION

SBS children with short remaining SB, missing ICV, and SBA etiology are more likely while NEC patients are less likely than others to necessitate tapering surgery. Postoperative PN weaning rates were comparable to patients who initially had more favorable intestinal anatomy and adapted without surgery.

Extent of small bowel resection does not influence the magnitude of intestinal adaptation in the mouse

PURPOSE

The magnitude of intestinal adaptation is considered to correlate with the extent of small bowel resection (SBR). However, this association has never been tested in mice. We sought to test the hypothesis that a greater SBR will induce a greater adaptation response.

METHODS

C57/B6 mice underwent 50% SBR, 75% SBR, or sham operation and were killed on postoperative day 7. The magnitude of adaptation was compared between 50% SBR and 75% SBR as changes in villus height, crypt depth, as well as rates of apoptosis and proliferation.

RESULTS

Seventy-five percent SBR led to decreased survival and increased weight loss compared with 50% SBR. The remnant ileum of both 50% SBR and 75% SBR displayed similar crypt expansion, enhanced villi, and increased apoptotic indices. Proliferation rates increased after 50% and 75% SBR equally.

CONCLUSION

Models of resection greater than 50% in mice result in greater morbidity and mortality and do not magnify the adaptation response to massive SBR. The use of more extreme resection models does not appear to provide added benefit for investigating mechanisms of intestinal adaptation.

Intestinal lengthening for short bowel syndrome

Our recommendation at this time is that surgical bowel lengthening be considered in any chronically PN-dependent patient when there is substantial bowel dilation, regardless of remnant bowel length. Timing is determined when maximal adaptation has been achieved or when the rate of progression in enteral calories is slow and hampered by bacterial overgrowth. Currently, it seems premature to recommend primary STEP in all patients in whom surgical lengthening is considered, but it is certainly technically easier than the Bianchi procedure. These procedures are clearly indicated in patients experiencing life-threatening complications of PN, but careful selection of patients without evidence of hepatic decompensation is important. Patients with advanced liver disease are poor candidates for lengthening and should be referred for intestinal transplantation instead.

Neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a major cause of morbidity and death in neonates. The 30% to 50% mortality rate for NEC with perforation has not changed appreciably in the past 30 years. The critical relevant outcomes following NEC include survival, gastrointestinal function, and neurodevelopmental status. In each of these areas, initial anecdotal and case-series analysis has been followed by studies using more sophisticated methods of analysis. The single most important predictor of outcome, besides gestational age, is whether or not the disease has progressed to the point requiring surgical intervention. Patients with NEC requiring operation have a high mortality. Moreover, the vast majority of morbidity following NEC occurs in the patients who survive following operation. The purpose of this review is to examine the evolution of evidence regarding outcomes for patients with NEC and to provide an update on our current state of knowledge.

Small intestinal bacterial overgrowth: roles of antibiotics, prebiotics, and probiotics

Small intestinal bacterial overgrowth is common in intestinal failure. Its occurrence relates to alterations in intestinal anatomy, motility, and gastric acid secretion. Its presence may contribute to symptoms, mucosal injury, and malnutrition. Relationships between bacterial overgrowth and systemic sepsis are of potential importance in the intestinal failure patient because the direct translocation of bacteria across the intestinal epithelium may contribute to systemic sepsis: a phenomenon that has been well established in experimental animal models. The accurate diagnosis of bacterial overgrowth continues to present a number of challenges in clinical practice and especially so among patients with intestinal failure. The management of patients with bacterial overgrowth remains, for the most part, primarily empiric and comprises antibiotic therapy and correction of any associated nutritional deficiencies. Although evidence from experimental animal studies consistently indicates that probiotics exert barrier-enhancing, antibacterial, immune-modulating, and anti-inflammatory effects, which all could be benefits in small intestinal bacterial overgrowth and intestinal failure, their role in human beings remains to be evaluated adequately.

The effects of surgery on gastrointestinal motor activity

Gastrointestinal surgical procedures have the potential to disrupt motor activity in various organs of the gastrointestinal tract or, indeed, throughout the entire alimentary canal. Several of these motor effects have important clinical consequences and have also served to advance our understanding of the regulation of gastrointestinal motor activity. This review will focus, in particular, on the effects of surgery on the small intestine, and will attempt to emphasize the implications of these studies for our understanding of small intestinal motility, in general.