Intestinal and Multivisceral Transplantation 

Updated: May 24, 2018
Author: Richard K Gilroy, MBBS, FRACP; Chief Editor: Ron Shapiro, MD 

Overview

Background

Until recently, parenteral nutrition was the standard of care for all patients with intestinal failure. The success of kidney, liver, and heart transplantation has increased with the advent and application of new antirejection medications coupled with improved surgical techniques. Advances in intestinal transplantation, by contrast, have been slow to develop until recently. At the turn of the 20th century, Alexis Carrel demonstrated the technical feasibility of intestinal transplantation; however, acute allograft rejection was an insurmountable obstacle in the absence of immunosuppressive medications.[1] In the 1960s, surgeons demonstrated renewed interest in intestinal transplantation following early successes with kidney transplantation. This interest rapidly waned as the inadequacy of the immunosuppressive medications available at the time became apparent.

Total parenteral nutrition (TPN) became available in 1969, with a number of patients relying on it for complete support. At first, all patients on TPN required continuous hospitalization. Today, TPN is safely used in outpatient management. Pooled data from the North American Home Parental and Enteral Patient Registry show 1- and 4-year survival rates for patients with short bowel syndrome (SBS) who received TPN at home to be 94% and 80%, respectively. Only 5-11% of deaths were directly attributed to TPN, with the vast majority of deaths related to progression of the underlying primary disease.

The success of TPN supplanted the then urgent need to find solutions for the problems with intestinal transplantation, and TPN became the standard of care. Recently, however, intestinal transplantation has been offered to that minority of the patients on long-term TPN who have severe and life-threatening complications related to this therapy.[2, 3] This restricted indication is, however, likely to be broadened as a consequence of the improved patient and graft survival and cost-effectiveness data that have been seen in the last few years.

Complications of TPN

The complications of long-term TPN are listed below. Those marked (**) are also indications for intestinal transplantation:

Infection:

  • Catheter sepsis (recurrent**)
  • Exit-site infection
  • Tunnel infection

Catheter occlusion:

  • Thrombosis (≥2 access sites**)
  • Dislodgment or breakage
  • Mineral or lipid precipitate

Hepatic disease

The rate of hepatic disease reaches 15-40% after 3 years of TPN. Patients may develop the following:

  • Hepatic steatosis (most common finding)
  • Cholestasis
  • Phospholipidosis
  • Progressive fibrosis**
  • Cirrhosis**

Renal disease

  • Electrolyte disturbance
  • Decreased glomerular filtration rate**
  • Recurrent acute kidney injury**

Gastrointestinal disease

  • Gastroparesis
  • Bacterial overgrowth
  • Disuse enteritis
  • Intestinal hypoplasia

Metabolic bone disease

  • Osteomalacia
  • Osteoporosis

Biliary disease

After 6 weeks of TPN, up to 100% of patients have biliary disease. Biliary sludge is almost universal; gallstones may develop.

History of the Procedure

Intestinal transplantation achieved a clear recognition in the management of complicated total parenteral nutrition (TPN) with Medicare approval (see below). The relatively brief history of this procedure before this included dismal outcomes prior to 1990 and a moratorium during 1994 as a consequence of the high morbidity and mortality associated with the procedure. However, in 1995, rapid improvements in outcomes were seen as results of technical and immunosuppression development.

On the immunosuppression side, the introduction of tacrolimus was one of the cornerstones of success.[4] On the technical side, programs were guided by the recommendations developed by the American College of Surgeons in 1995. Growth since then has been exponential, as is well illustrated in the 2012 report of the Intestinal Transplant Registry.[5]

By and large, this success is a consequence of multiple endeavors. These include progress in immunosuppressive therapy, refinement to surgical techniques,[6] improvement in post-transplant care, better understanding of intestinal immunology, and protocols implemented for anti-infectious monitoring and prophylaxis (primarily against cytomegalovirus [CMV] infection). These actions have translated to improvements in patient and graft survival over the last few years. With this, intestinal transplantation will soon be cost effective; this author believes that intestinal transplantation is not far away from supplanting TPN in the management of short bowel syndrome that requires long-term TPN.[7] Data from Sudan support the cost-effectiveness following 2 years after transplantation.

On October 4, 2000, the US Health Care Financing Administration (HCFA) approved coverage by Medicare for intestinal transplantation. Medicare agreed to cover all types of intestinal transplants for patients with irreversible intestinal failure who have specific life-threatening complications (noted with ** above) from long-term intravenous nutrition and TPN. Medicare's criteria for approved centers include an annual volume of at least 10 intestinal transplants and a 1-year actuarial survival of at least 65%. The decision was important because most state Medicaid and other third-party payers in the United States followed suit and provided reimbursement for intestinal transplantation.

Significant shifts in intestinal transplant programs have been noted along with a significant reduction in the number of transplants in the United States over the last 5 years. Concurrent with this reduction, transplant programs have placed a greater focus on refining and optimizing the management of patients with rehabilitation and are using multidisciplinary approaches to intestinal failure and short bowel syndrome.[8] Evidence supports that this measure has reduced the likelihood of developing an indication for intestinal transplantation; when coupled with refinements in the management of TPN-dependent intestinal failure (with novel agents like teduglutide), the authors feel reductions in overall listings will continue over time.

In 2013, the UNOS Liver and Intestinal Transplantation Committee of the United States revised the organ allocation policy. They sought to reduce what was a high wait list mortality for combined liver and intestinal transplantation (LSBT). The committee gave a priority in the allocation system above the current model for end stage liver disease (MELD) allocation for recipients awaiting LSBT.[9] Interestingly, the percentage of patients removed for death on the wait list over the last 4 years has reduced; this occurred prior to implementation of the new allocation policy.

Wait list removals due to all reasons since the year 2000 are as follows:

  • 2000 - 135

  • 2001 - 192

  • 2002 - 189

  • 2003 - 215

  • 2004 - 226

  • 2005 - 279

  • 2006 - 283

  • 2007 - 293

  • 2008 - 276

  • 2009 - 245

  • 2010 - 205

  • 2011 - 173

  • 2012 - 178

  • 2013 - 156

Wait list removals due to transplant received since the year 2000 are as follows:

  • 2000 - 78

  • 2001 - 111

  • 2002 - 106

  • 2003 - 112

  • 2004 - 145

  • 2005 - 170

  • 2006 - 170

  • 2007 - 193

  • 2008 - 185

  • 2009 - 178

  • 2010 - 150

  • 2011 - 125

  • 2012 - 105

  • 2013 - 99

Wait list removals due to death or transplant-preventing illness since the year 2000 are as follows:

  • 2000 - 30

  • 2001 - 50

  • 2002 - 57

  • 2003 - 56

  • 2004 - 57

  • 2005 - 70

  • 2006 - 67

  • 2007 - 57

  • 2008 - 50

  • 2009 - 36

  • 2010 - 22

  • 2011 - 26

  • 2012 - 20

  • 2013 - 23

Wait list removals due to improved condition since the year 2000 are as follows:

  • 2000 - 7

  • 2001 - 3

  • 2002 - 11

  • 2003 - 20

  • 2004 - 6

  • 2005 - 12

  • 2006 - 15

  • 2007 - 12

  • 2008 - 17

  • 2009 - 17

  • 2010 - 21

  • 2011 - 8

  • 2012 - 29

  • 2013 - 18

Table 1. Intestinal Transplant Programs - 2011. (Open Table in a new window)

Total Number of Programs

Number of Programs Doing Transplants

Number of Transplants in Largest Center

Number of Transplants in Smallest Center

33

19

26

1

 

Total Transplants (n=184)

Indiana University Health (INIM)

Four Centers at 1

 

Over the last 5 years, the total number of transplants and total number of listings for intestinal transplantation has declined.

Problem

Intestinal failure is a term applied to individuals who are unable to maintain adequate nutrition with an enteric diet. These patients require TPN to maintain energy (caloric) intake. The causes of intestinal failure include anatomic and functional abnormalities and, along with the population affected, are listed as follows:

  • General population

    • Short bowel syndrome

    • Motility disorder

    • Other causes

  • Pediatric patients

    • Midgut volvulus

    • Pseudo-obstruction

    • Gastroschisis

    • Aganglionosis or Hirschsprung disease

    • Necrotizing enterocolitis

    • Microvillous inclusion disease

    • Intestinal atresia

  • Adult patients

    • Ischemia (venous or arterial infarction)

    • Pseudoobstruction

    • Crohn disease

    • Trauma

    • Radiation enteritis

    • Desmoid tumor

    • Other causes (eg, tumor [neuroendocrine], Gardner syndrome [familial polyposis], midgut volvulus)

Patients with SBS have insufficient small bowel length to support energy (caloric) needs; this typically occurs when at least 80% of the small intestine has been resected. Resection of less than 80% of the length of the bowel is generally accompanied by intestinal adaptation and subsequent enteral tolerance. Considerable interindividual variability occurs among patients. Some individuals may require TPN despite having less than 80% of their small intestine resected, while others may not require TPN after more extensive resections. This fact emphasizes the importance of trials of enteral tolerance and nutritional rehabilitation while assessing an individual with SBS (see Intestinal rehabilitation).

Additional factors that may help predict those likely to achieve enteral tolerance include younger age, the presence of an ileocecal valve, and the presence of an ileum. The functional causes of intestinal failure in those with normal bowel length include intestinal aganglionosis, chronic idiopathic intestinal pseudoobstruction, and congenital mucosal abnormalities such as microvillous inclusion disease.

Indications

Indications for transplantation

The most common cause of death for individuals permanently dependent on TPN is liver failure. Steatohepatitis and cholelithiasis with or without associated cholecystitis are common in patients on TPN and warrant exclusion before the physician makes a diagnosis of TPN-induced liver disease. Advanced TPN-induced liver disease is irreversible; however, when it is identified early it is often reversible with discontinuation of TPN.

Progressive liver disease is more common in young children on TPN and is often associated with a history of multiple resections and recurrent infection. Progressive and irreversible liver disease develops in 2-42% of children and adults with intestinal failure due to SBS.[10, 11, 12, 13, 14] The development of liver disease may be related to enteric stasis, the ability to establish some degree of enteral tolerance, catheter-related sepsis, age, a history of prematurity, the extent of bowel resection, the presence of an underlying inflammatory condition, or the length of time on TPN.[15, 16, 17, 18, 12, 14] The mediators and pathways responsible for the progression of TPN-associated liver disease to end-stage liver disease remain undefined.

Two other causes of life-threatening complications in patients with intestinal failure include recurring sepsis and loss of vascular access due to venous thrombosis.[18, 19] These problems are often concomitant. Sepsis associated with indwelling catheters is more common in children; in some patients, recurrent sepsis is related to gastrointestinal stasis and bacterial overgrowth. Overall, the mortality rate associated with catheter-related sepsis has progressively diminished with the introduction of flexible, silastic, silicone rubber catheters; tunneled, cuffed catheters; and improved line care.[20, 21, 22]

Less common indications for intestinal transplantation include locally invasive desmoid tumors, premalignant conditions (Gardener syndrome), and fluid and electrolyte losses unmanageable with TPN.[23]

In summary, intestinal transplantation is a salvage procedure applied to patients who have either anatomic or functional diseases that preclude enteral tolerance (eg, intestinal failure) and have life-threatening complications of TPN such as progressive liver disease, a history of catheter-related sepsis, or loss of vascular access.[23, 24] It cannot be overemphasized that measures to augment intestinal function and minimize the risk of complications of parenteral nutrition (PN) must be explored in every patient on PN to avoid the need for this procedure. There is not an established role for preemptive intestinal transplantation, ie, transplantation in the absence of complications of PN or invasive intra-abdominal desmoid tumor. There is, however, a very clear indication to refer patients early to centers of excellence in intestinal failure and transplantation in the setting of ultrashort bowel or major catheter-related complications.[25]

To illustrate the problems faced in the setting of intestinal transplantation, an illustration of the variables and the impact of these variables upon the patient's outcome must be remembered.

  • Patients who are admitted from home for their transplant procedure have better survival rates than those who are inpatients at the time they are taken to the transplant procedure.

  • Central vascular access is required for the procedure and in settings in which access is reduced and technical complications and management of posttransplantation complications is increased. Loss of access complicates the procedure by limiting alternative sites for central access should a catheter need to be removed or repositioned. This central access is important for the provision of perioperative PN and is essential for resuscitation, perioperative fluids, and medication maintenance required in the peritransplant period.

  • At some centers, clinicians have decided that the transplantation cannot be performed if all upper and lower central access is lost, which illustrates the necessity for referral if vascular access loss develops. Access loss of 2 major access sites is generally an indication for intestinal transplantation. Patients with a significant loss to central vascular access may lose eligibility for transplantation. This illustrates the necessity for referral if vascular access loss begins to develop.

  • Advanced liver disease may not preclude isolated intestinal transplantation; however, in the presence of advanced liver disease, isolated intestinal transplantation is generally not possible.

  • Waiting list mortality is higher in those awaiting LSBT than in those awaiting isolated liver transplantation or isolated bowel transplantation.

  • In patients who undergo intestinal transplantation and lose their graft and have indications for retransplantation, outcomes in retransplantation are inferior to outcomes for the primary transplantation.[26]

Patient evaluation

The goals of patient evaluation for intestinal transplantation are as follows:

  • Establish the primary diagnosis.

  • Evaluate and document TPN complications experienced by the patient.

  • Establish the length and function of the remnant native intestine.

  • Assess the function of the remnant intestine and potential for establishing enteral tolerance.

  • Determine the degree of liver dysfunction and the potential for reversibility.

  • Identify any comorbid conditions that may impact upon the outcome of intestinal transplantation, and identify potential problems (eg, thrombosis of major vessels).

  • Assess candidate suitability (including families) for the rigors of intestinal transplantation and the ability to comply with the often complex posttransplant regimens.[27]

One critical aspect of the evaluation process is to determine whether the patient's intestinal failure is potentially reversible. Most information regarding nutritional assessment comes from a carefully obtained patient history. Particular attention is given to TPN regimens, prior attempts to achieve enteral tolerance, current enteral feeding protocols, growth, development, and exclusion of nutritional deficiencies. Multidisciplinary consultation with experienced pediatric nutritionists, gastroenterologists, and hepatologists is invaluable before determining the presence or absence of nutritional deficiencies and complications from long-term TPN. Many routine screening studies are listed in Workup.

In addition to a thorough history and review of operative records, evaluation of the length and function of the remnant native bowel is further accomplished through radiographic contrast studies. These studies help delineate the length of the remaining small bowel, its anatomic location, the presence or absence of the ileocecal valve, the caliber of the remaining small and large intestine, and the transit time from the proximal to distal bowel. These studies also may help define surgically correctable diseases that permit enteral tolerance without transplantation. Occasionally, additional motility studies are necessary.

The medical and surgical team must be rigorous when establishing the presence of intestinal failure and when defining its cause because Munchausen syndrome by proxy has been reported in an intestinal transplant recipient.[28] For patients with functional disease, review of histopathologic findings following bowel biopsy is important to confirm the diagnosis and extent of bowel involvement.

During the assessment of TPN complications, the physician must decide whether a patient's TPN-related liver disease is reversible. This decision may be difficult, and considerations include liver biopsy findings and the likelihood of progression during the waiting period. The presence of dense, bridging fibrosis may prompt consideration of LSB transplantation. Minor amounts of fibrosis associated with cholestasis may allow ISB transplantation. However, if rapid progression of the disease is observed and a long waiting period is anticipated (eg, small infants), combined listing for LSB transplantation may be indicated.

An assessment for manifestations of portal hypertension is important, although diminished mesenteric blood flow secondary to the short remnant intestinal length provides protection against varices. Increasing splenomegaly, cytopenia, dilated superficial abdominal veins, and bleeding from gastrostomy sites or stomata provide clues to the presence of portal hypertension. The bilirubin level alone is not a good indicator of whether ISB or LSB transplantation is indicated. ISB transplantation in jaundiced patients has been shown to reverse liver disease, even in patients with a total bilirubin level of 20 mg/dL at the time of transplantation.[29]

Doppler ultrasonography is used to assess venous access and to determine the patency of the central veins. Intestinal transplantation is considered when the patient has lost 2 or more common venous access sites, such as the subclavian or internal jugular veins, or when unconventional sites such as the right atrial, transhepatic, or direct inferior vena caval catheters are required.

Patient history and previous records should reveal the number and type of organisms responsible for previous central venous line infections. Fungal infections requiring mechanical ventilation or vasopressor support are most worrisome.[19, 30] Furthermore, a history of infection with multidrug-resistant organisms should raise concern for future mortality and should be considered in the overall assessment.

Comorbid conditions can greatly increase the likelihood of complications in the posttransplant period. Specific evaluations of other organ systems are dictated by patient history and are further directed by any abnormalities identified from the results of baseline studies. For example, intestinal failure as a consequence of necrotizing enterocolitis may be associated with a history of prolonged neonatal ventilation and bronchopulmonary dysplasia. These conditions are associated with repeated hospitalizations and a propensity for prematurity in infants, which may give rise to behavioral and developmental problems that should be identified and addressed as early as possible. However, controlled trials to support this are lacking. The authors strongly believe that early intervention facilitates posttransplant recovery and that such interventions are important. Portions of these evaluations are incorporated into the psychosocial assessment of the patient and the patient's support system.

Relevant Anatomy

Relevant donor anatomy

For isolated intestinal transplantation, en bloc removal of the donor intestine commences at the pylorus and proceeds as far as the terminal ileum.

Anatomy of the donor operation, with procurement o Anatomy of the donor operation, with procurement of the liver, small bowel, pancreas, and spleen en bloc (AO, thoracic aorta; HA, hepatic artery; PV, portal vein; CBD, common bile duct; D1, first part of the duodenum; TI, terminal ileum).

Inclusion of the colon in the graft has been associated with worse patient survival, presumably because of increased septic complications as demonstrated by researchers from the University of Pittsburgh. Inclusion of the stomach has been associated with poor gastric motility (personal communications). The superior mesenteric artery and vein provide the blood supply to the organ.

When performing a combined LSB transplantation, the duodenum and head of the pancreas are retained in the allograft. In preparation for multivisceral transplantation, other abdominal organs are obtained at the time of intestinal procurement, most commonly the entire donor pancreas.

The allograft is prepared in the operating room before implantation.

The recipient's requirements dictate which technique should be performed; these requirements are described later. For all recipients, bowel continuity is the ultimate goal, and proximal and distal enteric anastomoses are performed at the time of allograft implantation.

A more comprehensive outline of these procedures is available in the 1999 article by DeRoover and Langnas.[31]

Contraindications

Although most contraindications to transplantation are relative and a collection of factors might present an absolute contraindication, the following is a list of conditions and situations in which transplantation may be contraindicated:

  • Profound disabilities that are not likely to be corrected by transplantation

  • Severe extraintestinal illnesses that are not likely to be corrected by transplantation

  • Uncontrolled sepsis

  • Immunodeficiency (with the possible exception of immunodeficiency associated with multiple intestinal atresia)

  • Nonresectable or disseminated malignancy (including large hepatoma, desmoid tumour)

  • Complete loss of vascular access or insufficient central access sites (lack of central access during transplantation and during the early posttransplantation period)

  • Absence of psychosocial support or willingness to comply with posttransplant regimens

  • Anatomical elements (size of cavity for the allograft, vascular inflow and outflow)

 

Workup

Laboratory Studies

See the list below:

  • Complete blood cell count

  • Prothrombin time and activated partial thromboplastin time

  • Electrolytes, blood urea nitrogen, and creatinine

  • Total and direct bilirubin

  • Aspartate transaminase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transferase

  • Serum albumin

  • Phosphorous and magnesium

  • Cholesterol and triglycerides

  • Zinc and selenium

  • Free and total carnitine

  • Vitamins A, D, and E

  • Cytomegalovirus (CMV), Epstein-Barr virus (EBV), hepatitis B virus, hepatitis C virus, and human immunodeficiency virus

  • Alpha-fetoprotein

  • Cytotoxic antibody screen

Imaging Studies

See the list below:

  • Chest radiography

  • Abdominal ultrasonography

  • Doppler study of upper extremity veins

  • Bone age study

  • Echocardiography

Other Tests

See the list below:

  • Electrocardiography

  • Motility studies (as indicated)

  • Liver biopsy (as indicated)

  • Upper gastrointestinal endoscopy

Histologic Findings

TPN cholestasis without significant fibrosis (This is a reversible pathology at this point.)

PN cholestasis. (This is a reversible pathology at PN cholestasis. (This is a reversible pathology at this point as an absence of fibrosis.)
 

Treatment

Medical Therapy

Therapeutic options

At the completion of the evaluation, the physician should recommend one of the following therapies: continued medical therapy with TPN, ISB transplantation, LSB transplantation, multivisceral transplantation, or isolated liver transplantation.

If intestinal failure is not confirmed during the evaluation, intestinal transplantation is not indicated. Likewise, if the patient does not exhibit evidence of life-threatening complications of TPN administration, risk-benefit and survival analyses support continued TPN administration. Isolated intestinal transplantation is the simplest surgical option and offers potential elimination of TPN and its complications. The results of ISB transplantation have not supplanted long-term TPN in the management of SBS in the absence of TPN-associated complications.[32, 33, 24, 23] However, more recent reports, with 1-year survival rates exceeding 90%, suggest that ISB transplantation might soon challenge TPN as the primary therapy for TPN-dependent intestinal failure.[34]

Importantly, if the patient shows evidence of potential to advance enteral nutrition, guidance is offered to such individuals to facilitate this. These patients should be enrolled in an intestinal rehabilitation clinic (see Intestinal rehabilitation). Periodically reevaluated, these specialized multidisciplinary clinics optimize TPN regimens, evaluate for complications of TPN, augment intestinal adaptation, and establish timely referral for surgery or transplantation, if needed. Transplantation for intestinal failure, at this point, might be best viewed as a salvage procedure for patients with progressive complications of TPN.

In 2008, the results of a multicenter trial examining teduglutide, a GLP-2 analogue, were presented by O'Keefe and Messing at Digestive Diseases Week in the United States and at the European Society of Parenteral and Enteral Nutrition.[35] The multicenter study examined the ability of teduglutide to reduce parenteral nutrition in patients on long-term TPN. This study demonstrated an ability to reduce parenteral nutrition, increase citrulline levels, and increase villus height in the active treatment arm. This therapy certainly shows promise in the treatment of patients on long-term parenteral nutrition. These results were duplicated in a second multicenter phase 3 study with 63% (27 of 43) of patients treated with teduglutide responding with a greater than 20% reduction in PN at 24 weeks as compared with 30% (13 of 43) of patients treated with placebo (p =0.002).[36]

With the domain of growth factors it is unclear what the impact will be upon number of people developing indications for transplantation in intestinal failure.

Surgical Therapy

LSB transplantation is recommended for individuals with irreversible liver injury and intestinal failure. These patients have more severe disease than recipients who receive ISB grafts, and patients waiting for LSB transplantation constitute the majority of intestinal transplant candidates. Waiting list mortality rates are high, and patients are often in intensive care units at the time of transplantation.

Multivisceral transplantation includes transplantation of grafts of other abdominal viscera along with the liver and intestinal grafts. This may include the stomach, pancreas, kidney, and/or colon. This procedure is usually reserved for patients with additional organ system failure (eg, pancreatic insufficiency, diabetes, kidney failure), often on a background of a nonreconstructible gastrointestinal tract.

Multivisceral transplantation is also indicted for patients with duodenal fistulae or locally aggressive tumors that can only be treated with massive abdominal evisceration.[19] The main drawback with including the stomach appears to be poor emptying, and authorities at some centers completely avoid this by performing a gastrojejunostomy between the allograft and a small native gastric remnant. Surgeons at the University of Pittsburgh have demonstrated that inclusion of the colon diminishes survival and is not recommended.

Although some researchers have demonstrated adequate stomach function after LSB transplantation in patients with motility disorders, Tzakis suggested that multivisceral transplantation with removal of the native stomach at the time of transplantation is indicated for these patients. However, other researchers are not necessarily in agreement with this approach.[30, 31, 32] Patients who receive multivisceral grafts have lower overall survival rates compared with patients who receive other types of intestinal allografts.[19]

In a small group of predominantly pediatric patients, liver dysfunction related to TPN progresses during the period in which enteral tolerance is being established after intestinal resections. This is usually during the initial evaluation period and, in a select few centers, has been noted to follow aggressive intestinal rehabilitation. If enteral tolerance is likely to be achieved following transplantation, isolated liver transplantation may be recommended.[33, 34]

To date, at the University of Nebraska, isolated liver transplantations have been performed in 11 children with TPN-associated liver disease; 8 children are currently alive and 7 have been successfully weaned from TPN. In this group, assessment of adequate bowel length is best accomplished by demonstrating enteral tolerance. A history of weight gain during the administration of 50% or more of the energy (caloric) requirements via the enteral route is encouraging. Surrogate markers for the potential of further adaptation include the remaining length of small bowel relative to the patient's age and the presence of the ileocecal valve.[35] The high waiting list mortality rate for LSB transplant candidates makes this is an attractive option for carefully selected patients.

The goal of intestinal transplantation is to eliminate the need for TPN and to reverse or prevent TPN-associated liver disease. The clear disadvantage of intestinal transplantation is the considerable morbidity and mortality associated with the procedure and with the morbidity and cost associated with long-term immunosuppression.

An important publication by Kato et al compared patient and surgical outcomes from intestinal transplantation in which the colon and ileocecal valve was included as part of visceral transplantation procedure with those without.[37] They identified benefits in stool volume and frequency without additional morbidity or mortality risk. Limitations to this study include its retrospective nature and potential selection biases.

When considered in the context of others reports reviewed by Matsumoto,[38] the evidence suggests improved stool patterns and potential for fecal continence, potential further improvements in quality of life indices over those already achieved with intestinal transplantation,[39] and no increase in risk of allograft loss, provided the candidates for this are well selected.

Preoperative Details

Waiting list mortality

The waiting list mortality rate is nearly 50% for LSB candidates and approximately 10% for ISB candidates although this may have changed in the last 4 years. The lower mortality rate for ISB candidates is principally related to a lesser degree of liver disease. However, the mortality rate for ISB transplantation is underestimated because patients whose disease progresses may require the combined procedure and therefore are not included in ISB mortality figures. At the University of Nebraska, 30% of patients placed on the ISB waiting list develop progressive liver dysfunction and become LSB candidates; half of these patients die while waiting for a transplant.[29] The mean waiting time is more than twice as long for patients whose status has changed compared with those who undergo isolated intestinal transplantation.[29]

Donor selection and organ procurement

Intestinal transplant donors typically include those donors who would be suitable for other forms of organ donation. The donor should be stable and have no evidence of significant metabolic acidosis, and the donor should be matched to the recipient by ABO blood type, size, and medical urgency according to United Network of Organ Sharing status. Approximately two thirds of intestinal transplant recipients have SBS and, as a consequence, have shrinkage of the peritoneal cavity or loss of peritoneal domain.[23]

In order to decrease the number and viability of passenger lymphocytes in the extensive lymphoid tissue of the gut, surgeons at the University of Nebraska typically administer both antithymocyte globulin (Thymoglobulin) and muromonab-CD3 (Orthoclone OKT3) intraoperatively to cadaveric donors.[31] Researchers from the University of Pittsburgh recently presented data that support the use of allograft irradiation. In animal models, the large lymphocyte load of the donor organ has been shown to predispose the transplant recipient to graft versus host disease (GVHD); however, under current regimens the rate is 2-5%. The effect of either regimen on chimerism and long-term rejection is largely unknown and is an area for further investigation.

Primary or recurrent CMV enteritis appears to occur more frequently after intestinal transplantation than after other solid organ transplantation; CMV enteritis is associated with a higher risk of graft loss or patient death.[40, 41] therefore, surgeons at the University of Nebraska select CMV-negative recipients, with the recognition that seropositivity in infants younger than 1 year may be the result of circulating maternal antibodies.[42]

Intraoperative Details

As previously mentioned, the definition of the types of allografts are varied.

Detailed reviews of the surgical procedures involved in intestinal and multivisceral transplantation are beyond the scope of this article. Please refer to previously published descriptions of these techniques.[43, 31, 44, 45] .

Media files 3-9 demonstrate some steps of the surgical procedures.

Back table operation with mesenteric vessels held Back table operation with mesenteric vessels held within the forceps and the donor intestine within preservation solution.
Intestinal graft within the abdominal cavity of th Intestinal graft within the abdominal cavity of the recipient at the time of revascularization.
Revascularized bowel prior to closure. In the lowe Revascularized bowel prior to closure. In the lower right corner the anastomosis between the donor small bowel and recipient remnant colon can be seen.
Picture of the liver and small bowel allograft. Th Picture of the liver and small bowel allograft. The liver is to the left of the picture, and the spleen can be seen lying within the loops of the small bowel (spleen is removed later).
Removal of the native liver. Left behind is the ca Removal of the native liver. Left behind is the cavity into which the liver and small bowel allograft will be placed.
Postrevascularization image of the liver and small Postrevascularization image of the liver and small bowel allograft.
The allograft, prior to closure, positioned within The allograft, prior to closure, positioned within the recipient's abdomen. The wedge-shaped excision (biopsy site) seen on the donor organ was performed at organ procurement. These biopsies are selectively performed to review the suitability of organs in instances where issues of suitability are raised.

Postoperative Details

After the operation, the patient is returned to the intensive care unit, where hemodynamic monitoring and mechanical ventilation are performed as needed. Doppler ultrasonography is routinely performed on postoperative day 1 to assess vessel patency or as clinically indicated.

The standard immunosuppression drugs following intestinal transplantation are tacrolimus and steroids. Tacrolimus is administered orally in a dose sufficient to provide a blood level of approximately 20-25 ng/mL by the end of the first postoperative week. Steroids are administered at a dose of approximately 20 mg/d for adults and 0.3 mg/kg for children. No evidence indicates that the routine addition of azathioprine, mycophenolate, cyclophosphamide, or antilymphocyte therapy decreases the frequency or severity of acute rejection, but the addition of these agents may lead to an increased risk for infection and other immunosuppression-related complications.[46, 47]

Some benefit may be achieved with the simultaneous administration of either sirolimus or mycophenolate in patients who receive reduced doses of tacrolimus because of renal toxicity or in patients who experience refractory acute and/or chronic rejection.[48] The protocol at the University of Nebraska Medical Center is to routinely administer basiliximab, an interleukin 2 receptor antagonist, on the day of surgery and on postoperative day 4 to reduce the chance of rejection. This has decreased the rate of rejection from 85% to 35%.

Because of the high rate of infectious complications, broad-spectrum antibacterial and antifungal prophylaxis is administered for 1-2 weeks after transplantation, and prophylactic ganciclovir has been recommended. Other prophylactic regimens target prevention of herpes simplex virus (HSV) infection, EBV infection, and Pneumocystis carinii pneumonia.[29]

The appearance of allograft ostomy and the amount of ostomy output are useful clinical signs of graft dysfunction. Ostomy losses of up to 100 mL/kg/d are acceptable and can be compensated for with supplemental intravenous fluids. Because no serological or biochemical tests are diagnostic for small bowel rejection, the routine protocol is endoscopy with biopsy. A high index of suspicion for rejection and abdominal perforation is warranted in any intestinal transplant recipient with unexplained fever, diarrhea, or gastrointestinal bleeding.

Enteral nutrition is provided as soon as intestinal function returns. In the absence of other clinical complications, enteral feedings are started on the third-to-fifth postoperative day. The concentration and type of enteral nourishment are tailored to the patient's clinical response. A low-fat diet is used in the early posttransplant period. On average, recipients of ISB allografts are successfully weaned from parenteral nutrition by the third or fourth week posttransplant. After 4-6 weeks, an unrestricted diet is allowed.

Occasionally, the recipient does not establish enteral feeding; this is sometimes referred to as food aversion. Ancillary services, including speech therapy, may be helpful in these patients. Enteral feeding can be withdrawn as oral feeding approaches energy (calorie) requirements. The administration of loperamide, often in high doses, may be helpful for reducing ostomy losses and is often used early after transplantation, although no controlled trials support this.

Immunosuppression medications

These agents inhibit immune-mediated responses to the transplanted allograft. By doing so, allograft rejection is prevented. These agents also diminish inflammatory responses.

The cornerstone to a vast majority of immunosuppression protocols is tacrolimus (Prograf). Tacrolimus is a potent antagonist of calcineurin activation and 10-100 times more potent than cyclosporin. To act, tacrolimus binds to the FK binding protein, and this leads to antagonism of calcineurin and through this, inhibition of NF-AT-supported IL-2 gene expression. Tacrolimus also attenuates the response to cytokine stimulation. The effect of these actions leads to suppression of cellular immune responses and T-cell activation. In adults, the dose is 300-500 mcg/kg/d PO/NG divided twice daily. Dosages are subsequently directed by target levels for immunosuppression needed at various times posttransplant; different centers have different protocols (see Table below). The pediatric dose is the same as the adult dose. Tacrolimus must not be coadministered with cyclosporine.

Methylprednisolone (Adlone, Medrol, Solu-Medrol) decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability. Adult patients are given an intraoperative bolus followed by 200 mg/d IV divided q6h for 4 doses, then 160 mg/d IV divided q6h for 4 doses, then 120 mg/d IV divided q6h for 4 doses, then 80 mg/d IV divided q6h for 4 doses, then 40 mg/d IV divided q12h for 2 doses, then are switched to prednisolone 20 mg PO qd. Children < 20 kg are given 20 mg/kg intraoperatively followed by 10 mg/kg/d IV divided q6h for 4 doses, then 8 mg/kg/d IV divided q6h for 4 doses, then 6 mg/kg/d IV divided q6h for 4 doses, then 4 mg/kg/d IV divided q12h for 2 doses, then 2 mg/kg/d IV divided q12h for 2 doses, then 1 mg/kg/d for 1 dose, and then switched to prednisolone 0.3 mg/kg/d PO qd.

Basiliximab (Simulect) is a chimeric monoclonal antibody that specifically binds to and blocks the interleukin-2 (IL-2) receptor on the surface of activated T cells. Adults dosing depends on body weight. Adults < 20 kg are given 10 mg on days 0 and 4; adults >20 kg are given 20 mg on days 0 and 4. The dosage is not established for children < 2 years. Children aged 2-15 years are given 12 mg/m2 IV, not to exceed 20 mg. The dosage in children >15 years is the same as it is in adults.

Alemtuzumab (Campath) is a monoclonal antibody against CD52, an antigen found on B cells, T cells, and almost all CLL cells. It binds to the CD52 receptor of the lymphocytes, which slows the proliferation of leukocytes. In adults, the dose is 0.3 mg/kg IV preoperatively and then repeated postoperatively. Administer an additional dose on each of postoperative days 3 and 7. The pediatric dose is not established.

Sirolimus (Rapamune) inhibits lymphocyte proliferation by interfering with signal transduction pathways. It binds to immunophilin FKBP to block action of mTOR. It is FDA-approved for prophylaxis of organ rejection in patients receiving allogeneic renal allografts. Dosages and levels should be adjust no more often than twice per wk initially, and monitoring of levels should be started 4 d after initiating medication unless specific indication exists for more frequent monitoring (eg, medication interacting with rapamycin metabolism) In adults, 2-5 mg PO qd is used and loading doses are discouraged. Trough blood concentrations >8 ng/mL are correlated with immunosuppressive activity. The pediatric dose is not established. In patients who develop chronic allograft rejection, sirolimus might initially play an important role. Before a conclusion can be made, additional case reports and case series are needed. Everolimus, a newer mTOR inhibitor, might be equally effective.

Antithymocyte globulin (Thymoglobulin) is a purified concentrated gamma-globulin (primarily monomeric IgG) from hyperimmune horses immunized with human thymic lymphocytes. The mechanism of action is thought to be its effect on lymphocytes responsible in part for cell-mediated immunity and lymphocytes involved in cell immunity. Its immunosuppressive action is generally similar to other antilymphocyte preparations. However, they may differ qualitatively and/or quantitatively in the extent to which they produce specific effects, in part because of factors such as source of antigenic material used, type of animal used to produce antiserum, and method of production. A hematologist or another physician with extensive experience must be involved in the administration and monitoring of antilymphocyte serum because of the many complications and adverse effects of this therapy. Dose and duration of therapy vary with different investigational protocols. In adults, the dose is1.5mg/kgIVondays1,3,5,7.Thepediatricdoseisnot established.

Alemtuzumab is a powerful antilymphocyte antibody that produces profound and long-lasting lymphopenia and has been used at some centers in intestinal transplantation as an induction agent much akin to thymoglobulin. A study, albeit retrospective in nature, demonstrated no difference in bacterial infections with alemtuzumab compared with daclizumab (withdrawn from the market) when used in combination with thymoglobulin. Importantly, the quality of this study and other reports of alemtuzumab use in intestinal transplantation warrants both the need for randomized multicenter studies and caution when considering its use.

Antibiotics

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Piperacillin and tazobactam (Zosyn) is an antipseudomonal penicillin plus a beta-lactamase inhibitor. It inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active multiplication. In adults, the dose is 3.375 g IV q8h for 7 d. The pediatric dose is 200-300 mg/kg IV q8h for 7 d.

Trimethoprim and sulfamethoxazole (Bactrim, Septra) inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid. Its antibacterial activity covers common urinary tract pathogens except Pseudomonas aeruginosa. In adults, the dose is 80 mg TMP/400 mg SMZ PO bid every Monday and Tuesday. Do not administer to children < 2 months. In children >2 months, the dose is 1 mL/kg/d suspension PO divided bid every Monday and Tuesday, not to exceed 10 mL/dose.

Antivirals

Nucleoside analogs are initially phosphorylated by viral thymidine kinase to eventually form a nucleoside triphosphate. These molecules inhibit HSV polymerase with 30-50 times the potency of human alpha-DNA polymerase.

Ganciclovir (Cytovene) is a synthetic guanine derivative active against CMV. It is an acyclic nucleoside analog of 2'-deoxyguanosine that inhibits replication of herpes viruses both in vitro and in vivo. levels of ganciclovir-triphosphate are as much as 100-fold greater in CMV-infected cells than in uninfected cells, possibly because of preferential phosphorylation of ganciclovir in virus-infected cells. In adults, the dose is 5 mg/kg IV bid for 14 d followed by treatment with acyclovir. The pediatric dose in children < 3 months is not established. In children >3 months, administer ganciclovir as in adults.

Acyclovir (Zovirax) inhibits activity of both HSV-1 and HSV-2. It has affinity for viral thymidine kinase. Once phosphorylated, it causes DNA chain termination when acted on by DNA polymerase. Patients experience less pain and faster resolution of cutaneous lesions when it is administered within 48 h of rash onset. It may prevent recurrent outbreaks. Early initiation of therapy is imperative. In adults, the dose is 80 mg/kg/d PO divided qid for 1 y, not to exceed 800 mg/dose. The pediatric dose is the same as the adult dose.

Antifungals

The mechanism of action of antifungals may involve alteration of RNA and DNA metabolism or intracellular accumulation of peroxide that is toxic to fungal cells.

Fluconazole (Diflucan) has fungistatic activity. It is a synthetic oral antifungal (broad-spectrum bistriazole) that selectively inhibits fungal cytochrome P-450 and sterol C-14 alpha-demethylation, which prevents conversion of lanosterol to ergosterol, thereby disrupting cellular membranes. In adults, the dose is 400 mg PO/IV qd for 4 wk. The pediatric dose is 5 mg/kg PO/IV qd for 4 wk. It is critical to remember that the use of antifungals leads to effects on tacrolimus levels. Should these be discontinued or commenced, tacrolimus dosing likely needs to be adjusted and monitoring of levels must be increased.

Prostaglandins

Alprostadil is identical to naturally occurring prostaglandin E1.

Alprostadil (Prostaglandin E1, PGE1) possesses various pharmacologic effects, including vasodilation and inhibition of platelet aggregation. In both adults and children, the dose is 0.2-0.6 mcg/kg IV continuous infusion over 1 h for 7 d.

Proton pump inhibitors

These agents are used in patients who require complete acid suppression. Patients taking omeprazole via NG tube should have granules mixed with an acidic juice. Following administration, the NG tube should be flushed to prevent blockage.

Omeprazole (Prilosec) decreases gastric acid secretion by inhibiting the parietal cell H+/K+ ATP pump. In adults, the dose is 20 mg PO/NG bid. The pediatric dose is 0.5 mg/kg PO/NG q12h.

Salicylates

These agents inhibit prostaglandin synthesis, which prevents formation of platelet-aggregating thromboxane A2.

Aspirin (Anacin, Ascriptin, Bayer Aspirin) is used to treat mild to moderate pain. A low dose may be used to inhibit platelet aggregation and improve complications of venous stasis and thrombosis. In adults, the dose is 80 mg PO/PR qd. The pediatric dose is 40 mg PO/PR qd. Caution when using salicylates; creatinine values must be tracked.

Immune globulins

These agents neutralize circulating myelin antibodies through antiidiotypic antibodies. Immune globulins down-regulate proinflammatory cytokines, including INF-gamma. They also block Fc receptors on macrophages, suppress inducer T and B cells, and augment suppressor T cells. The administration of immune globulins may increase CSF IgG levels by 10%. Immunoglobulins may be used in the setting of rotavirus infection and occasionally in the setting of antibody-mediated rejection.

CMV hyperimmune globulin (CytoGam) is used to prevent CMV disease in immunosuppressed recipients of organ transplants. In both adults and children, the dose is 150 mg/kg IV postoperative day 3, then 100 mg/kg qwk IV for 4 wk, then 50 mg/kg/mo for 1 y.

Table 5. Proposed Immunosuppression Targets (Open Table in a new window)

Medication

Days 2-29

Days 30-89

Days 90-179

Days 180-365

After 1 year

Tacrolimus (monotherapy levels)

15-20 ng/mL

12-15 ng/mL

10-12 ng/mL

7-10 ng/mL

Taper to around 5 ng/mL

Tacrolimus (in combination levels)

10-15 ng/mL

8-12 ng/mL

8-10 ng/mL

5-8 ng/mL

2.5-5 ng/mL

Prednisone (dose)

20 mg

15 mg

10 mg

7.5 mg

5 mg

Rapamycin (to be used only in combination with tacrolimus)

6-10 ng/mL

5-8 ng/mL

5-8 ng/mL

5-8 ng/mL

5-8 ng/mL

Mycophenolic acid (suggested dose as listed and to be used only in combination with tacrolimus; dose listed is adult dose; intolerance may be managed by lowering dose)

1000 mg bid

1000 mg bid

Cease unless renal indication exists

...

...

Complications

Rejection

Rejection episodes occur in 70-90% of recipients following intestinal transplantation, although hyperacute rejection is rare.[23, 29, 49, 50] The median number of rejection episodes per patient is 2.5 and does not differ with the type of allograft.[50] Most episodes respond to steroid bolus therapy, and only 20% of patients require muromonab-CD3 or thymoglobulin for treatment of steroid-resistant rejection. With newer immunosuppressive protocols the incidence of rejection in intestinal transplant recipients has declined markedly in the last 5 years.[34]

Concurrent liver transplantation has been proposed to offer protective benefits, but these effects have not been universal. Recent data, reported by Fishbein and others at the International Small Bowel Transplant Symposium in Stockholm, Sweden have provided optimism that newer immunosuppressive protocols, which include sirolimus and other agents (eg, alemtuzumab [Campath]), may lower the frequency of rejection and may reduce immunosuppression-related adverse effects while improving survival. A more recent review, published in 2008, looked again at the protective effect of a concurrent liver with intestine transplantation versus intestine transplantation alone.[51] This review revealed a trend toward a protective effect and reduced incidence of acute rejection at one year; however, this trend did not reach significance.[51]

The development of moderate or severe acute intestinal graft rejection is a poor prognostic indicator and is associated with a mortality rate of 40%.[29] Graft enterectomy can be performed in ISB recipients with severe rejection; however, removal of the intestinal graft from recipients of composite grafts is technically more challenging and is generally not performed. High mortality occurs in this situation. Salvage therapy with agents such as sirolimus has shown favorable outcomes[52] ; however, no randomized studies have been performed, and a randomized study of sirolimus in intestinal transplantation to assess for a role in chronic or acute rejection is unlikely.

Infection and sepsis

Sepsis is the most frequent cause of death following intestinal transplantation.[23] Frequently involved factors include intra-abdominal infection or abscess, bowel perforation, line infection, wound infection, pulmonary infection, urinary tract infection, and viral enteritis. Sepsis is not uncommon with acute rejection, and this should always be remembered when evaluating a septic patient. Approximately 40% of small bowel transplant recipients require further surgery during their original inpatient stay; additional surgery is usually the result of infectious complications.[47] Furthermore, these complications are primarily responsible for the prolonged hospitalizations of these patients; ISB recipients typically are hospitalized for 3 weeks to 3 months, and LSB recipients typically are hospitalized for 3-6 months.

Following small bowel transplantation, typical pathogens are enteric organisms, fungal species, or staphylococci (associated with central venous line infections). Bacterial infection appears to be far more common if the colon is included in the allograft; thus, inclusion of the colon is not the recommended protocol in many centers.[53] Empiric antibiotic selection is based on the focus of infection and previous resistance patterns of positive isolates. The regimen should be modified based on culture results. In view of the high propensity for translocation of gut-derived bacteria, researchers at the University of Pittsburgh recommend surveillance stool cultures to direct empiric antibiotic selection at the onset of apparent infection.[54]

Cytomegalovirus infection

CMV disease occurs more frequently after intestinal transplantation than after other types of solid organ transplantation. When present, involvement of the allograft occurs in more than 90% of cases.[53] In the past, more than half of intestinal transplant recipients developed symptomatic CMV infection.[53] Recipients of grafts from donors who are seropositive for CMV have a worse outcome than recipients of grafts from seronegative donors.[55, 41] In light of this observation, a policy to avoid donor-positive/recipient-negative transplantations was adopted by the University of Nebraska, which has probably contributed to the reduced incidence of CMV disease observed at this center. Most infections are diagnosed following endoscopic biopsy; the remainder are identified during evaluations of febrile patients.

Lymphoproliferative disease

Posttransplant lymphoproliferative disease (PTLD) is a complication of over-immunosuppression. PTLD is a lymphoma that occurs after transplantation, and it is frequently associated with EBV infection.[56] PTLD occurs in 6-29% of intestinal transplant recipients, and children appear to have an increased frequency of PTLD compared with adults.[47, 23, 57, 29] The peak incidence appears to be at 2 years. Ongoing graft monitoring is essential during therapy for PTLD because graft rejection may occur on a background of reduced immunosuppression, with the potential for graft loss. Recently improved outcomes for those diagnosed with this condition have been demonstrated with treatment with the anti-CD20 antibody, rituximab.[58, 59, 60]

Graft versus host disease

GVHD following intestinal transplantation has been far less common than one might expect considering the substantial volume of lymphoid tissue present in both the mesentery and the Peyer patches of the intestinal allograft. The rate of GVHD after intestinal transplantation is 0-16%.[61, 49, 47, 29] Transplantation programs with higher reported GVHD rates use simultaneous bone marrow infusion, which may contribute to the increased prevalence of GVHD.[61, 62]  Strategies to prevent GVHD include graft irradiation and the administration of antilymphocyte serum.[63] All blood products should be irradiated. Treatment with pulse methylprednisolone generally is effective for controlling mild cases.[64] Unfortunately, a nonspecific presentation and diagnostic delay appear to contribute to the high mortality associated with GVHD.

Chronic rejection

Chronic rejection is becoming more apparent over time. Patients present with failure to thrive, diarrhea, and, occasionally, sepsis. Routine small bowel biopsy results may show mucosal atrophy, although results also may demonstrate minimal, if any, change. This is because obliterative vasculitis and fibrosis, which are often factors involved in chronic rejection, are localized to layers of the small bowel deeper than the biopsy procedure can access. For this reason, biopsy results may be falsely reassuring. Often, at later stages, patients need to be explanted and may later become candidates for repeat intestinal transplantation. As with other forms of transplantation, repeated bouts of acute rejection, duration of the rejection episode, response to steroids, and severity of any rejection episode predict the possibility of developing chronic rejection.

Retransplantation

There has been significant improvements to 1-, 3-, and 5-year survival following intestinal and liver-intestinal transplantation. However, situations arise in which retransplantation needs to be considered. In retransplantation, recipients of a second graft are more commonly adults as recipients of the second allograft compared with the primary transplant. Unfortunately, retransplantation has inferior outcomes in patient survival compared with primary transplantation. The type of retransplanted graft (liver and small bowel vs isolated bowel) does not appear to affect outcome.[26]

Renal dysfunction

As the long-term survival rates of intestinal recipients improve, more complications related to the immunosuppressive management will occur. Among the most serious of these complications is chronic renal disease. The frequency of chronic renal dysfunction among patients who underwent intestinal transplantation appears higher than among recipients of any other form of nonrenal solid organ transplant.[65] The renal dysfunction is multifactorial in origin; intestinal allograft dysfunction likely contributes to the high incidence, although this has never been studied. To reduce the incidence of renal dysfunction, close monitoring of hydration parameters is an important component of posttransplant health maintenance. In the face of chronic renal dysfunction, early nephrology referral and possible revisions to immunosuppression strategies might be considered.

Outcome and Prognosis

Quality of life

The International Transplant Registry and several large centers have shown that 77-93% of surviving recipients remain independent of parenteral nutrition beyond 6-12 months after transplantation.[49, 23, 29] Rovera and colleagues examined 10 adult recipients of successful intestinal transplantation and 10 adult patients who were stable on home parenteral nutrition. They reported that quality of life was similar between the groups. The major difference was that further improvement over time was observed in the group that received intestinal transplants.[66]

Another study on quality of life examined 30 recipients in whom graft function was maintained beyond 1 year. Rehabilitation potential was excellent, and 92% of recipients returned to school or work.[67] On the other hand, the prolonged need for intense immunosuppression was associated with rehospitalization in 50% of patients during the preceding year, and poor linear growth in 25% of pediatric transplant recipients occurred despite seemingly adequate allograft function.[67]

A study of pediatric intestinal transplant patients used the CHQ and Pediatric Quality of Life (PedsQL4.0) instruments to measure health-related quality of life (HRQOL). Patient responses on the CHQ did not differ from those of healthy normal children; however PedsQL4.0 summary scores in the school functioning subcategory and psychosocial health categories were significantly lower.[68]

Patient and graft survival

The results of intestinal transplantation were reported at the Sixth International Small Bowel Transplant Symposium. Reports came from several single-center series, including Omaha, Paris, Miami, and Pittsburgh. Worldwide, pooled data through 1997 on the outcomes of intestinal transplantation are reported through the Intestinal Transplant Registry.[23] A total of 446 patients were enrolled in the registry. Most patients were younger than 13 years, and only 35% of the patients were older than 16 years. Surgeries performed included ISB (45%), LSB (40%), and multivisceral (15%) transplantations.

The 1-year survival rate for patients undergoing intestinal transplantation after 1995 was approximately 65%, and the 1-year graft survival rate was 60%. Statistical analysis of the registry data revealed that the factors significant for determining outcome included center size and type of allograft. Transplantation programs wherein more than 10 intestinal transplantations were performed had significantly improved survival. A patient survival advantage was noted for those patients receiving either an ISB or LSB transplant compared with those receiving a multivisceral transplant; no apparent survival advantage was conferred by the use of living-related donors.[23]

The most common cause of death was sepsis (47%), followed by multiorgan failure (26%), graft thrombosis (10%), PTLD (10%), and graft rejection (4%).[23] The most common reason for graft failure was refractory rejection.[23] More recent data published from the Intestinal Transplant Registry in 2007 highlighted the improved survival rates, with 1-year survival rates after intestinal transplantation identified as approaching those of liver allograft recipients.[69]

Survival figures 2007. Image courtesy of the Intes Survival figures 2007. Image courtesy of the Intestinal Transplantation Registry (ITR).

At the Second International Congress on Immunosuppression (December 2001; San Diego, Calif), some of the larger programs (including the University of Nebraska and the University of Pittsburgh) reported significant reductions in rejection. This is likely to lead to improved long-term survival over time.[5] However, after 2000, the Intestinal Transplant Registry reported a rise in the 1-year survivals of both patients and grafts to about 75%.

With this improvement, a difference between isolated small bowel (ISB) and combined liver-small bowel (LSB) transplantation or multivisceral transplants in terms of graft survival however equivalent patient survival. Adding to this success, further improvement in survival rates have been over the last 10 years. Data from the most recent report of the intestinal registry made on Bologna, Italy highlighted this and further support that both outcomes continue to improve for both the patient and allograft.

One reason for improvements was a reduced rate of acute rejection amongst recipients. An increased use of induction therapy, in particular, basiliximab, may have accounted for some of this success. In addition, transplantation of a higher ratio of patients as outpatients rather than as inpatients and transplantations carried out in centers with increasing experience (>10 transplants) appears to have contributed to the improved outcomes. Data from the registries of most solid organs suggest that a critical volume needs to be achieved to support best outcomes.

In summary, program experience, refined surgical and programmatic techniques, and patients in better clinical health at the time of transplant have all contributed to improved outcomes. With regard to the proportion of patients waiting at home, earlier referral of patients to intestinal failure and transplant centers contributes to better patient outcomes.

Unfortunately, survival results must be viewed with reservation. The outcome of this procedure needs to be considered many years along. The Intestinal Transplant Registry indicates that long-term graft survival continues to decline and, importantly, chronic rejection is not an uncommon problem in allografts. As discussed above chronic rejection leads to recurrence of the primary pathology (ie, intestinal failure) and is most common in those who are not compliant with posttransplant regimens.[27, 3] Intestinal transplantation is common in young children. This author is concerned that allograft loss from this pathology will become an increasing problem as the population of pediatric patients who have been transplanted enters into late adolescence. In addition, one particular morbidity accompanying this procedure is the frequency of endstage renal disease. This complication has been identified as decreasing long-term survival in intestinal transplant recipients.[48]

A division exists in outcomes. Overall, the average the 1-year survival rate appears to be improving; however, the 5-year allograft survival rate has remained stable.[2] These data may be interpreted in different ways; however, one of the most evident arguments is that long-term immunosuppression or failure of immunosuppression carries significant morbidity. Unfortunately the changes in survival are confined to the first year post-transplant by in large. In the long run, the critical area in need will focus on the better management of patients in the period following this.

Intestinal rehabilitation: the alternative

Intestinal rehabilitation is an emerging subspecialty. It focuses on measures to optimize enteral tolerance while concurrently assessing, preventing, or managing the complications of PN. Rehabilitation is most successful when undertaken by multidisciplinary teams with a coordinated approach. These groups use modifications to diet, in association with judicious use of medications, to optimize enteral tolerance of the bowel that is present. In some instances, surgical procedures are performed to remove areas of stasis or to lengthen the bowel. Pivotal to the success of intestinal rehabilitation is the patient's participation within the framework of a multidisciplinary team.[70] . Sudan and others have shown reductions in PN following these procedures; weaning from PN has been achieved in several patient following lengthening with step-enteroplasty.

Intestinal failure is defined as a reduction of intestinal absorption so that macronutrient, water, electrolyte supplements, or a combination thereof are needed to maintain health or growth. Severe intestinal failure is when PN, fluid, or both are needed. Mild intestinal failure is when oral supplements or dietary modification suffice. Short bowel syndrome (SBS) is present when failure results from intestinal loss and failure to adapt by 1 month.

Approximately 10,000-20,000 patients with SBS are treated each year in the United States. The incidence is 1-2 cases per 100,000 persons per year, and this accounts for approximately one third of home PN users. The severity of the disease generally correlates with remnant bowel length and the loss of the ileocecal valve. Over the past decade, the severity of SBS has been better correlated with the absolute function of the intestine that remains, as enormous interindividual variability is present. Of those patients on home PN, the survival rate is 90% for instances in which PN was commenced for benign disease as compared with 15% 1-year survival rates in cases in which PN was commenced for intestinal failure that developed as a consequence of malignant disease.

Intestinal rehabilitation monitors for complications of PN. These complications include the following:

  • Line infections

    • Sepsis 0.4-2 times per year (Catheters used for TPN have less catheter colonization than catheters used for other indications.)

    • Endocarditis, phlebitis

  • Occlusion 0.1 times per year

  • PN-related liver disease

  • Iatrogenic effects (malposition, migration, leaks)

  • Metabolic effects (osteopenia/osteoporosis, diabetes mellitus), electrolyte levels, fluid levels, vitamin deficiencies

  • D-lactic acidosis

  • Manganese and aluminium toxicity

  • Stone disease (renal, biliary)

  • PN nephropathy

The intestinal rehabilitation program diet involves graduated introduction of a diet from day 5 postresection, when the ileus has resolved. Dietary components may involve some of the following recommendations:

  • Iso-osmolar restriction to 500 cal/d initially, followed by graduated increases to caloric intake

  • Encourage salt and carbohydrate combinations, especially in patients who have a jejunostomy (avoid simple concentrated carbohydrates in isolation)

  • Liquid supplements (gluconate forms)

  • Rice starch products

  • Medium chain triglycerides

  • Fat restriction

    • Restrict fat to around 30% of daily intake if colon is in continuity (combined with soluble fibers and complex starches).

    • If the patient has no colon, fat restriction may not be necessary, as fat is felt to be a good energy source in these patients.

  • Glutamine

  • Lactose avoidance

  • Oxalate avoidance

  • Jejunostomies isotonic high sodium (encouraged target is 90 mmol/L)

  • Fiber

    • Clinical trial data suggest that fiber assists ostomy outputs by modifying the consistency of these outputs.

    • Soluble fiber metabolism is an important potential source of nutrition in some patients (fermented to short chain fatty acids [SFA]).[71, 72]

Medical approaches include the following:

  • Acid suppression (H2 blocker, proton pump inhibitor)

  • Antidiarrheal medications (high dose)

  • Vitamin supplements (high dose)

  • Caution with Mg and K supplements (These supplements may be required to offset losses. However, the physician must recognize that both may contribute to ostomy losses at higher doses and that short transit times may reduce the efficacy of tablet forms.)

  • Cholestyramine (with caution)

Intestinal adaptation postsurgery is generally near completion by 6 months after the procedure. Medical therapies to consider at that time include the following:

  • Bacterial overgrowth management (generally applied as therapeutic trials of antibiotics with clinical responses the end point to be monitored for)

  • Octreotide may be considered to treat refractory diarrhea, although tachyphylaxis develops and use in patients with in situ gallbladders increases the likelihood of cholelithiasis.

  • Clonidine may assist by acting to reduce high outputs for the GI tract (Use caution, as the use of this drug may be associated with hypotension, particularly if initiated in a dehydrated patient.)

  • Pancreatic enzymes (to be used, in particular, in patients with risk for deficiencies of pancreatic enzymes)

  • Bisphosphonates[73]

  • Growth hormone[74]

  • Glucagonlike peptide-2 (GLP-2)[75]

Surgical approaches, in addition to those that restore continuity and manage infections, focus primarily on increasing intestinal length and enhancing function. These surgeries are a form of autologous gastrointestinal reconstruction (AGIR) and include the following:

  • Tapering enteroplasty

  • Bowel plication

  • Reverse segments

  • Creation of intestinal valves

  • Kimura procedure

  • Longitudinal intestinal lengthening[76]

  • Serial transverse enteroplasty (STEP)[77]

These approaches should be explored in an effort to avoid intestinal transplantation. Late referral to centers with clinicians experienced in SBS may limit the alternatives available. In the author's opinion, late referral may also increase the risk of complications related to any of the therapeutic options listed above.

Future and Controversies

Cost

The average cost of intestinal transplantation is $132,285 for ISB transplantation, $214,716 for LSB transplantation, and $219,098 for multivisceral transplantation.[49] As of 1992, the estimated average yearly cost of TPN administration—not including medical equipment, nursing care, or hospitalization—was approximately $150,000 per patient.[78]

Living-related transplantation and reduced-size grafts

Reduced-size LSB grafts have been introduced in an effort to address the high mortality rate due to prolonged waiting times, especially for children younger than 1 year.[79, 45] Living-related (live donor) small bowel transplantation has been performed, although long-term outcome data remain pending for both donor and recipient. Clearly, the number of potential donors would be dramatically increased if live donors or donors who are larger than recipients were routinely considered; however, the functional consequences of bowel reduction for transplantation in humans remain unknown.[80, 67] Another option, which was suggested by researchers at King's College, is sequential transplantation of the liver and, later, the small bowel, in a separate procedure.[81]

The use of reduced-size grafts may not greatly affect waiting list mortality. A shift to targeting prevention of liver disease associated with TPN along with intestinal adaptation measures may provide greater benefits.

Colon inclusion in the transplant

Tzakis and colleagues reported the outcomes of colon inclusion in the primary intestinal transplant procedure. Notable was the finding of improved outcomes over time for the intestinal allograft, as one might expect with a new procedure.[82] Including the colon certainly provides a necessary function in intestinal transplantation as it provides the function of the colon for its physiologic functions of water absorption, residue breakdown, and storage. Currently, increasing clinical evidence supports the efficacy of selective use of the colon in intestinal transplantation.[38]

Obstacles to general application

The primary obstacles to a general application of intestinal transplantation to all patients with benign and irreversible SBS are the consequences of both the procedure and the adverse long-term effects of immunosuppression. Further investigation into the immunology of the intestinal graft and targeted immunosuppression may enable surgeons to offer intestinal transplantation to any patient permanently dependent on TPN. Trials of a variety of immunosuppression regimens and the continued investigations into tolerance induction are being pursued in intestinal transplantation as for all forms of transplantation. The ultimate goal is a functional bowel free of rejection in a recipient without adverse effects of over-immunosuppression or specific medication-related complications. To minimize these complications, tailored regimens involving a variety of medications are being tested.

Although not currently a reality, future patients with uncomplicated intestinal failure may be considered for intestinal transplantation based on quality-of-life issues. Currently, the risks, benefits, and resources limit this procedure to people with complications of TPN, although this restriction is likely to change.

For patient education resources, see the Procedures Center, as well as Liver Transplant.

Guidelines for gastroenterologists

With recent improvements in the outcome of intestinal transplantation, this procedure may soon be more generally applied as treatment for uncomplicated TPN dependency. Comparisons have been made between the survival rates of patients receiving home TPN versus those who undergo intestinal transplantation. In the analysis, a comparison was made between published outcomes of the North American Registry of Home Parenteral Nutrition[30] and those of 141 consecutive intestinal transplantations at the University of Pittsburgh.[83] Although this comparison has limitations, it illustrates that the more general application of isolated bowel transplantation needs to be investigated and compared to long-term PN. This is unlikely to occur in a randomized fashion, and comparisons in the future will likely continue to be made to historic controls.

Information on the outcomes of those receiving home PN are limited. The exact number of people on TPN and the current frequency of complications of TPN in the US population are unknown. Most series in the literature are biased by the published data being generated from sources that have TPN expertise. By contrast, a sizable number of patients receiving HPN are not managed by these specialty groups. From this fact, one might assume that the complications of PN are higher and outcomes for long-term PN patients lower in those not managed by specialty groups. More important, however, is that timely referral for transplant evaluation improves outcomes.[84]

The incidence of patients with SBS has increased over the years because of progress made in intensive care medicine and parenteral nutrition techniques. This has created an increasing role for the general gastroenterologist and general surgeon for the long-term management of patients who survive massive resections and the long-term control of their TPN.

Early referral to centers with experience in intestinal failure and transplantation provides patients with the benefits of the multidisciplinary team and is associated with better survival rates and socioeconomic outcomes. An early referral allows all medical and surgical options for SBS to be explored. As time passes and TPN-associated complications develop, the therapeutic alternatives available to eliminate TPN may become limited. The emerging paradigm appears to be that patients with what seems to be irreversible intestinal failure should be referred to one of the limited centers with experience in both intestinal rehabilitation and intestinal transplantation.

The mortality rate of patients with SBS who receive HPN is about 30% after 5 years, which is still lower than the 5-year survival rate of patients with intestinal grafts and is about equal to survival rates of patients who have undergone intestinal transplantation. However, because the overall costs of a successful intestinal transplantation are already lower after 2 years than the cost of a prolonged HPN program, the procedure can be an economic alternative.[85]

The gastroenterologist who refers a patient for intestinal transplantation assumes an important role in the patient's management and long-term outcome. This is a consequence of the dispersed geography of patients with intestinal failure, the limited number of approved intestinal transplant facilities within the United States, and the need to coordinate patient care with an interested and invested local practitioner. After the patient is discharged from the transplant facility, the referring physician may assume responsibility for assessing nutritional outcomes, monitoring for complications of immunosuppression, and initial evaluating of rejection or infectious complications. Close liaison with the transplant center is encouraged. In the intestinal transplant recipient, allograft rejection remains a constant problem, and common clinical problems may present in an atypical presentation as a consequence, in part, of immunosuppression.

The current guidelines for intestinal transplantation

An article in 2011 by the Intestinal Failure Working Group of the European Society for Clinical Nutrition and Metabolism examined the current US Medicare guidelines that list indications for intestinal transplantation.[25] The group used a multicenter, multinational database and looked at the long-term follow-up of patients on home parenteral nutrition. Desmoid tumors and irreversible or progressive HPN-related liver failure constituted indications for life-saving intestinal transplantation (LSB or ISB), whereas central venous access–related major complications and ultrashort bowel might be indications for a preemptive/rehabilitative intestinal transplantation in select instances rather than all instances. The study showed also that patients on long-term stable PN had a clear survival advantage over transplantation at 5 years.

This paper led to readers comments and was followed by an aptly titled response of the authors, "Indications for intestinal transplantation—opinions and facts."[86] In the patient group designated as candidates for intestinal transplantation, of which 95% met Medicare and American Transplant Society criteria for major central venous catheter complications or ultrashort bowel syndrome, the 5-year survival rates were 83% on HPN and 78% after ITx without liver and were similar to those observed in an equivalent population of bowel recipients in the United States. Their data, however, did suggest some support for preemptive bowel transplantation in select groups of patients in the first few years of PN dependence.

In line with guidelines falling under the domain of "controversies," this author agrees with the comments of Pironi and colleagues: "A comparative cost-utility study of HPN and ITx would help to adjudicate on the more contentious elements...Close and positive cooperation between experts dedicated to the medical and surgical treatment of intestinal failure."[86]

Bioengineered organs

In recent years, bioengineered intestinal allografts have been made. These have not reached a point of entering into human studies but may significantly reduce the need for multivisceral transplantation.[87, 88, 89]