usmle文件克氏外科学19版chapter

1、 CHAPTER 29SMALL BOWEL TRANSPLANTATIONAbigail E. Martin and Debra L. Sudanaccess. As more patients were sustained for longer periods with TPN, cholestasis leading to liver failure was increasingly recog- nized as a potentially fatal complication.3 Until recently, transplantation or death appeared to

2、 be inevitable once a patient developed parenteral nutritionassociated liver disease (PNALD). However, a new investigational fish oilbased lipid formulation has been reported to prevent or even reverse TPN- induced cholestasis,4 and may be the next major breakthrough in this field.Early investigatio

3、nal ms of intestinal transplantationwere being developed long before the advent of TPN, but were doomed to failure because of a lack of understanding of immu- nology. The first investigation of intestinal transplantation as novel therapy for intestinal failure is attributed to Alexis Carrel in 1905.

4、5 Approximately 50 years later, in 1959, after the earli- est successful kidney transplantation in Boston, Lillehei and colleagues6 at the University of Minnesota published their suc- cessful work transplanting intestines using a canine m . Starzl and associates7 in Pittsburgh reported transplanting

5、 a cluster of organs, including the intestine, in dogs in 1960. The first published human intestinal transplantation was performed by Lillehei and coworkers8 in 1967, but the patient unfortu- nately did not survive because of thromboembolic complica- tions. Over the next few years, there were severa

6、l other unsuccessful attempts in humans,9 primarily because of theHISTORYDisease processes that lead to an inability to sustain oneself via normal enteral nutrition remain a therapeutic challenge to patients and physicians alike. The terms short gut syndrome and short bowel syndrome are often used t

7、o describe patients who are dependent on total parenteral nutrition (TPN) because of sig- nificant loss of bowel length from a variety of causes, ranging from congenital malformations to traumatic injury to ischemic loss. Prior to the availability of TPN, short bowel syndrome was almost always fatal

8、 and, even with current therapies, extremely short remnant bowel length, less than 50 cm of jejunoileum in adults, is associated with a 43% 5-year mortality.1 However, the term short bowel syndrome excludes a subset of patients who may have a normal or near-normal intestinal length. Inflammatory ill

9、nesses such as Crohns disease, motility disorders such as intes- tinal pseudo-obstruction, and diseases of the enterocytes such as intestinal epithelial dysplasia share the same devastating conse- quence of being unable to sustain oneself via enteral means. For this reason, the term intestinal failu

10、re represents a more accurate and fully inclusive term when describing patients who are unable to tolerate enteral feedings.Dudrick and associates seminal work2 in the laboratory showing that puppies could achieve near-normal growth pat- terns while exclusively sustained via hyperalimentation was on

11、e of the most significant medical breakthroughs of the century. Long-term TPN support increased patient survival, but also introduced a new set of problems, including potentially life- threatening infections and technical difficulties for maintaining682inability to control rejection, resulting in ov

12、erwhelming infec- tions. Given the apparent success of parenteral nutritional support, there was diminished enthusiasm for further clinical trials of intestinal transplantation.The advent of cyclosporine immunosuppression in the early 1980s coincided with descriptions of life-threatening com- plicat

13、ions associated with long-term TPN and led to renewed interest in the field of intestinal transplantation. Cohen and coworkers10 in Toronto reported the first isolated intestinal transplantation using cyclosporine in 1985 but, unfortunately, the 26-year-old recipient died on postoperative day 9. Ove

14、r the next 5 years, several successful intestinal transplants procedures were performed by Deltz,11 Starzl,12 and colleagues, resulting in patient survival ranging from 6 months to longer than 20 years.13 In the early 1990s, substantial improvements in control of rejec- tion accompanied the introduc

15、tion of tacrolimus immunosup- pression, and individual centers were able to demonstrate consistent successes.14,15 In the United States, over 1800 intesti- nal transplantation were performed through the end of 2009, based on Organ Procurement and Transplantation Network(OPTN) data ().historynontrans

16、plantation therapies for short bowel syndromeindications for intestinal transplantation evaluationanatomic considerations immunosuppression monitoring and rejection complicationsoutcomessSmall Bowel TranSplanTaTion Chapter 29 683NONTRANSPLANTATION THERAPIES FOR SHORT BOWEL SYNDROMEAlthough nontransp

17、lantation surgery is not the focus of this chapter, several novel surgical approaches were developed withopposite directions across the distended loops of bowel in a zigzag pattern, resulting in a decreased final bowel diameter that allows for more normal motility and absorption (see Fig. 29-1). An

18、International STEP Data Registry has been created to allow for the assessment of long-term follow-up of the efficacy and safety of the STEP procedure; the most recent publication has described the results in the first 38 patients undergoing the procedure at 19 centers.20 Another large single-center

19、series has described 21 additional patients, which along with the registry demonstrate that application of STEP in carefully selected intes- tinal failure patients can avoid the need for transplantation in 50% to 60% of cases.21 Furthermore, in contrast to the Bianchi lengthening, STEP can be applie

20、d as a secondary lengthening procedure after primary Bianchi or STEP, with success rates similar to those after the initial lengthening.22 Clearly, a multi- disciplinary approach with expertise in TPN management, non- transplantation surgical procedures, and intestinal transplantation is necessary t

21、o optimize care of the individual patient with intestinal failure.INDICATIONS FOR INTESTINAL TRANSPLANTATIONThe underlying causes of intestinal failure in pediatric patients referred for intestinal transplantation are more likely to result from loss of length caused by congenital diseases when compa

22、red with adult patients (Table 29-1). The Intestinal Transplant Reg- istry (ITR) has reported the three most common underlying disease states leading to transplantation in children as gastros- chisis (21%), volvulus (17%), and necrotizing enterocolitis (12%).23 In contrast, the most common indicatio

23、ns for intesti- nal transplantation in adults are ischemia (23%), Crohns disease (14%), and trauma (10%). Although the most common indica- tions fall under the category of short bowel syndrome, children and adults may suffer from diseases that result in dysmotility orthe goal ofizing function of the

24、 remaining intestine inshort bowel syndrome. These surgical therapies play an impor-tant role in the history of the treatment of intestinal failure and are therefore mentioned briefly here. As early as the 1950s, the surgical creation of segments of antiperistaltic loops of bowel was proposed in an

25、attempt to slow transit time in patients with limited intestinal length.16 Subsequently, it was recognized that the normal adaptive response to short bowel syndrome is to develop gradual dilation of the remnant segment, but this can lead to substantial dysmotility and bacterial overgrowth. Over time

26、, this practice has been abandoned because of resulting dysmotility and bacterial overgrowth in these antiperistaltic loops. Tapering of these dilated bowel segments by excision ofa portion of the bowel along thesenteric border toproduce a more normal diameter can then improve forwardmotion of chyme

27、, thus avoiding the need for resection of the dysmotile segment and further loss of length.17 In 1980, Bianchi18 described a novel alternative to resection and simple tapering consisting of separating distended bowel loops longitudinally so that two smaller diameter loops of bowel are created and re

28、anas- tomosed in an isoperistaltic fashion. The resulting bowel is twice the length, but with only half of the original diameter (Fig. 29-1). Given the technical challenges involved, when more potent immunosuppression became available, attention was largely refocused on intestinal transplantation.Ki

29、m and coworkers19 in Boston developed a technically simpler nontransplantation alternative to the longitudinal taper- ing and lengthening called serial transverse enteroplasty (STEP). This technique is performed by alternate staple firings fromABCDFIGURE 29-1 A, Distended bowel. B, Stepwise transver

30、se enteroplasty, showing alternating staple lines, thus reducing the diameter while increasing length. C, Bianchi enteroplasty, part 1. This is a longitudinal division of a loop of distended bowel so that the two leaves of the mesentery each supply one of the divided segments. D, Bianchi enteroplast

31、y, part 2. The divided segments are anastomosed to create a loop of bowel that is twice the length of the original loop, but with only half the original diameter.SECTION IV TranSplanTaTion anD immUnoloGY684SeCtION IV TranSplanTaTion anD immUnoloGYdespite optimal nutrition, and for patients with high

32、 morbidity, poor quality of life, or fluid or electrolyte abnormalities who cannot be successfully managed on an outpatient basis.26 Despite establishment of these criteria a decade ago, many referrals for intestinal transplantation continue to occur late in the patients clinical course. Currently,

33、75% of patients on the waiting list for intestinal transplantation also require a liver, thus placing more strain on an already limited organ supply.27EVALUATIONRecipient EvaluationAfter referral to an intestinal transplantation center, the patient undergoes evaluation to determine the extent of com

34、plications of intestinal failure and degree of comorbidities. Historical details and previous hospital records pertaining to surgical pro- cedures performed, previous intestinal rehabilitation attempts, and attempts at enteral feeding will be closely examined. Common diagnostic studies performed dur

35、ing the evaluation are listed in Table 29-2. Once a patient is deemed an appropriate candidate, he or she is placed on the waiting list within their United Network for Organ Sharing (UNOS) region. Transplan- tation centers may indicate weight and age spans for which they would consider potential don

36、ors, and each patient is assigned a status level according to her or his available venous access. Level 1 recipients are those who no longer have adequate central venous access via the jugular, subclavian, or femoral vein and all others are classified as level 2 candidates. Potential recipients who

37、also require a liver in addition to the intestine, are placed on the liver waiting list according to their m for end-stage liver disease (MELD) or pediatric end-stage liver disease (PELD) score (OPTN policy 3.11 on intestinal organ allocation).Donor EvaluationPotential cadaveric intestine donors are

38、 matched to appropriate size- and blood typecompatible recipients according to UNOS policiesfirst locally, then regionally, and finally nationally. When centers are evaluating a potential donor, consideration is given to existing intestinal pathology or past surgical history, such as extensive resec

39、tion or Roux-en-Y reconstruction.malabsorption, resulting in poor enteral function. For patients with short bowel syndrome, the remnant intestinal length and presence or absence of an ileocecal valve have been identified as predictive factors as to whether rehabilitation will be successful.24Depende

40、nce on parenteral nutrition alone, however, is not considered an indication for intestinal transplantation. To be considered for intestinal transplantation, patients must be depen- dent on TPN and have experienced life-threatening complica- tions of hyperalimentation. As early as 2000, the Center fo

41、r Medicare and Medicaid Services recognized the following indica- tions for transplantation of the intestine, with or without other organs, as standard of care for patients with irreversible intestinal failure: (1) overt or impending liver failure caused by PNALD;(2) multiple thromboses of central v

42、eins limiting central venous access; (3) more than two episodes of catheter-related infection requiring hospitalization in any year; (4) a single episode of fungal line infection; and/or (5) frequent severe dehydration, despite IV fluid supplementation and TPN. Chronic line infections, specifi- call

43、y fungal line infections, can be difficult to clear and can lead to venous occlusion, loss of available access sites, or death. Throm- bosis can also occur outside the setting of infection, leading to loss of potential central venous access sites. In addition, approxi- mately 50% of all patients on

44、TPN will develop PNALD,25 thus potentially requiring liver transplantation in addition to intesti- nal transplantation.In 2001, the American Society of Transplantation issued a position paper concerning indications for pediatric intestinal transplantation. In addition to the criteria noted, they als

45、o pro- posed that intestinal transplantation be considered for patients with intestinal failure that almost always results in early death,table 29-2 Some Diagnostic Studies for pretransplantation evaluationDIaGNOStIC StUDIeSeXaMpLeSlaboratory evaluationSerum chemistries, liver function tests,complet

46、e blood count, prothrombin timeinternational normalized ratio (pT-inr), partial thromboplastin time (pTT), platelet count, albumin, prealbuminSerologies forCmV, eBV, hepatitis panel, HiV infectious diseasesendoscopyUpper gastrointestinal (UGi) series, colonoscopy with biopsiespathologypercutaneous l

47、iver biopsyradiographicUGi with small bowel follow-through, CT of evaluationabdomen and pelvis, Dopplerultrasonography or magnetic resonance venographytable 29-1 Underlying Indications for Intestinal transplan- tationINCIDeNCeINCIDeNCepeDIatrIC(%)aDULt(%)Gastroschisis21ischemia23Volvulus17Crohns dis

48、ease14necrotizing12Trauma10enterocolitispseudo-obstruction9Desmoid tumors9intestinal atresia8motility disorders8retransplant8Volvulus7Hirschsprungs7Short gut, other7diseasemicrovillous6retransplant6inclusion diseasemalabsorption,4miscellaneous5otherShort gut, other4other tumors4other4Gardners3syndro

49、memotility2Tumor1From Intestinal Transplant Association (ITA): Intestine transplant registry: 25 years of follow-up results ().Small Bowel TranSplanTaTion Chapter 29 685Surgical TechniqueDonors may be deemed inappropriate based on EpsteinBarr (EBV) and cytomegalo (CMV) serologies, whichcould lead to

50、 post-transplantation lymphoproliferative disorder and severe enteritis in the recipients, respectively. Another con- sideration is the size of the donor compared with the recipient, because significant loss of abdominal domain after extensive resection may not allow accommodation of organs from lar

51、ger or even size-matched donors. In these cases, an ideal donor should have a weight 50% to 75% that of the recipient. Fur- thermore, long cold ischemia times of the intestinal allograft may lead to loss of mucosal integrity and bacterial translocation or intestinal perforation in the donor organ. T

52、herefore, consid- eration is given to any factor that could potentially increase the cold ischemia time, such as prior abdominal surgery in the donor and travel time between the recipient and donor medical centers. Close communication must occur between the donor and recipient teams to optimize timi

53、ng. As with all cadaveric organs, the final evaluation occurs during the procurement operation, during which the intestine is closely inspected for anatomic or perfusion defects that might preclude its use. Overall, intestine is recovered from potential donors less fre- quently than any other solid

54、organ, but rates of recovery have been increasing over time.28ANATOMIC CONSIDERATIONSIsolated intestinal transplants include the entire jejunum and ileum and their associated mesentery. Use of isolated intestine is limited to patients who lack or have reversible PNALD despite intestinal failure and

55、TPN dependence. Unfortunately, because of the frequency of end-stage liver disease in potential recipients, most require a combined transplant of the intestine with the liver. The nomenclature of grafts that include other organs with the intestine has been complicated by the inconsistent use of term

56、s among various centers. For example, a liver-intestine graft may refer to individual liver and intestine grafts from the same donor, but with each implanted separately. This requires recon- struction of the biliary drainage and complex vascular anasto- moses. More commonly a liver-intestine, or mul

57、tivisceral graft, includes the head or entire pancreas, whether or not the recipi- ent retains his or her native pancreas, because of the shared blood supply of the duodenum and pancreas with the liver and intes- tine grafts. Others use the term multivisceral or modified muti- visceral transplants o

58、nly when the stomach, colon, and/or spleen are included as part of the graft. A more reliable and perhaps simpler approach would be simply to name the organs included in the graft.Decisions as to which organs should be included are made based on the recipients underlying disease process and vary sli

59、ghtly based on individual center experience. Some centers have included stomach in the allograft for recipients suffering from gastroparesis preoperatively, with good functional results, whereas other centers have reported that the transplanted stomach may also suffer from gastroparesis.29 Historically, the right and transverse colon, which r