Surgery for Gut Failure: Auto-Reconstruction and Allo-Transplantation

Introduction

The successful clinical introduction of intestinal and multivisceral transplantation in the 1990s fueled a great interest in the management of patients with short gut syndrome (SGS) and gastrointestinal failure. With the early restricted utilization of transplantation as a rescue therapy, the concept of gut rehabilitation was introduced as a new therapeutic dimension to restore the nutritional autonomy of the native digestive system. These nontransplant rehabilitative measures include advanced nutritional care, new biologic therapy, and novel surgical techniques including autologous gut reconstruction and bowel lengthening. Adopting a multidisciplinary team approach, these therapeutic modalities have been successful in restoring nutritional autonomy in properly selected groups of patients without the need for visceral transplantation. Creative efforts have also been made to treat certain gastrointestinal malignancies with ex-vivo tumor resection and gut autotransplantation.

When attempts to restore nutritional autonomy fail, intestinal and multivisceral transplantation should be promptly considered, particularly for patients who can no longer be maintained on total parenteral nutrition (TPN). The procedure also offers a valid therapeutic option for patients with complex abdominal disease that is not amenable to conventional medical and surgical treatment. With the continual improvement in survival, intestinal and multivisceral transplantation has become the standard of care for gut failure in both children and adults. In 2000, Medicare and other commercial health insurances approved the procedure, particularly for patients who no longer can be maintained on TPN. Similar waves of clinical interest were witnessed across North America and Europe with an increase in the worldwide clinical practicality of the procedure, which is currently available in all continents but Africa. Such an achievement has been the result of surgical innovations, novel immunosuppressive protocols, and better postoperative management.

This chapter is designed to address the comprehensive strategic management of gut failure, including medical therapy, surgical rehabilitation, and intestinal transplantation. The newly introduced treatment algorithm is discussed in the setting of recent therapeutic advances with special reference to innovative surgical techniques. In addition, the current status of intestinal and multivisceral transplantation, including survival, graft function, and quality of life, are highlighted, with new insights to further improve the long-term therapeutic efficacy of the transplant procedures.

Gut Adaptation

Soon after each small bowel resection, the natural process of gut adaptation is initiated in both adults and children and continues for at least the next 2 years. The dynamic process includes structural and functional changes in the residual visceral organs with enhanced nutrient and fluid absorption. The extent of gut adaptation is commonly influenced by the site and extent of bowel resection, the presence of active intrinsic gastrointestinal disorders such as Crohn disease, early initiation of enteral feeding, growth of beneficial intestinal microbiota, and stimulation of the endogenous enterotropic factors, including glucagon-like peptide 2 (GLP-2). The different phases of such a natural phenomenon and its triggering mechanisms, including the potent stimulatory effect of luminal nutrients with upregulation of the colonic peptide transporter Pep T1, are discussed elsewhere. It is also our speculation that changes in the gut-brain neural circuit activities with altered gut neuropeptides may play an important role, with enhancement of intestinal gluconeogenesis and gut homeostasis.

Medical Management

Prompt comprehensive medical management and optimal nutritional care are the foundations of successful restoration of nutritional autonomy. In addition to TPN, treatment includes dietary modification, antidiarrheal medication, and oral hydration with vitamin, mineral, and trace element replacement. Since its inception in the 1960s, TPN has undergone several modifications to reduce associated life-threatening complications. For example, antibiotic-impregnated central indwelling catheters and ethanol-lock therapy were introduced to reduce risk of line infection, and more recently, a short-chain lipid formulation has been prescribed to reduce risk of hepatic injury.

Since its clinical introduction in 2005, omega-3 lipid formulation replaced the standard omega-6 storage-based lipids for children in many intestinal failure programs across both Europe and Canada. However, despite a reported significant reduction in serum bilirubin, there has been no noticeable effect on the degree of hepatic fibrosis, and the formulation has yet to become the standard of care in the United States. Efforts to optimize TPN are crucial to the interval and long-term management of patients with gut failure, particularly those who are not candidates for transplantation.

Pharmacologic manipulation of the gut adaptation process has been used increasingly in recent years. In addition to growth hormone, teduglutide (Gattex), a recombinant analog of human GLP-2, has recently been approved in the United States for the treatment of adult patients with intestinal failure due to SGS, including those with quiescent Crohn disease. Approval for the pediatric population is pending the results of a recently initiated clinical trial. The synthetic protease-resistance analogue, with a longer half-life, has been shown to promote changes in intestinal structure with increased villous height and crypt depth and a subsequent increase in the intestinal absorptive capacity. In addition, GLP-2 inhibits gastric emptying, increases intestinal transit time, suppresses gastric acid secretion, improves bone mineral density, protects intestinal barrier function, and increases intestinal blood flow. Nonetheless, there is a current need to establish standard criteria and practical guidelines to optimize the utilization and cost-effectiveness of such an expensive medical therapy.

Surgical Rehabilitation

Autologous Reconstruction

Preoperative planning with in-depth understanding of the underlying surgical disease and the residual gut anatomy is essential to achieve a successful outcome and minimize risk of postoperative complications. Each operation is an organ salvage procedure with conservative techniques guided by the embryonic development of the alimentary canal ( Fig. 73-1 ). Of crucial importance is complete awareness of any abnormal vascular and structural anatomy that may dictate the need for technical modifications to avoid injury of the residual native organs, particularly in patients with prior multiple abdominal operations and complex anatomy.

All surgical procedures should be performed with an open approach with placement of bilateral external ureteric stents in patients with frozen abdomens to avoid incidental ureteric injury. Sharp tissue dissection with use of thermal hemostatic tools is advisable. Excision of all scar and granulation tissues is essential to identify the residual organs with careful preservation of the segmental blood supply and any aberrant vasculature, particularly of the liver. All anastomoses must be tension-free and hand sewn in two layers using fine surgical techniques. Pyloroplasty is required with foregut reconstruction for drainage of a denervated stomach. Complete removal of any abdominal wall surgical mesh is necessary to avoid postoperative abdominal infection and recurrent enterocutaneous fistulae. Safe abdominal wall closure can be performed simply in a single layer using nonabsorbable material, particularly in patients with an infected abdomen.

Autologous reconstruction has frequently been used for patients with complex enterocutaneous and genitourinary fistulae, recurrent strictures, and loss of gut continuity ( Fig. 73-2 ). Most of these patients have hostile abdomens with loss of the main domain. Common operative findings in these patients with complex disease include a recalcitrant gut disorder, technically flawed surgery, and infected abdominal wall synthetic mesh. Foregut reconstruction is commonly indicated for patients with bariatric surgery–associated gut failure and other patients with complicated gastric surgery ( Fig. 73-3 ). With residual gastric segments, primary gastrogastric reconstruction is performed at levels dictated by the size and integrity of the segmental blood supply of the retained gastric portion(s). Proximal gastrogastric anastomosis ( Fig. 73-3, A ) is commonly performed with esophagogastric reconstruction ( Fig. 73-3, B ), which is often needed in patients with a small fibrotic gastric fundus and those with a disrupted esophagogastric junction. Complete salvage of residual portions of the stomach often requires two-level anastomoses, particularly in patients with combined high and low gastric disruption ( Fig. 73-3, C ). With proximal and mid gastric reconstruction, takedown of the short gastric vessels is often necessary, and a pyloroplasty is required for drainage. In addition, all efforts should be made to avoid disruption of the angle of His.

In patients with massive gastric necrosis and a prior gastrectomy, maintenance of the normal alimentary flow is crucial to restore full nutritional autonomy, particularly in patients with SGS. Therefore, innovative surgical techniques should be used to create a neostomach with a visceral conduit ( Fig. 73-4 ) to avoid exclusion of the duodenal from the alimentary flow and the accelerated exposure of the intestine to undigested nutrients. Interposition of a vascularized jejunal segment ( Fig. 73-4, A ) or colonic segment ( Fig. 73-4, B ) between the abdominal esophagus and gastric antrum or duodenum ( Fig. 73-4, C ) is effective in restoring gut continuity and optimizing absorptive capacity with achievement of full nutritional autonomy in patients with sufficient residual intestine. A pyloroplasty should be performed in patients with a retained antrum.

Midgut reconstruction has been the most common rehabilitative procedure, particularly in patients with mesenteric ischemia, Crohn disease, and adhesive disorders ( Fig. 73-5, A ). All efforts should be made to restore continuity of the hindgut, particularly in patients with residual large bowel and a spared anorectum ( Fig. 73-5, B ). When extensive hindgut resection is indicated—particularly in patients with Crohn disease, dysmotility, familial adenomatous polyposis, and colonic ischemia—it is our recommendation that the anal sphincters be preserved for a future pull-though operation using the donor colon at the time of transplantation. These genuine and technically challenging autologous reconstructive procedures have evolved as a result of our cumulative surgical experience in the field of abdominal visceral transplantation.