Combined Liver-Intestine Grafts Compared With Isolated Intestinal Transplantation in Children: A Single-Center Experience

The Importance Of Avoiding Time-Dependent Bias When Testing The Prognostic Value Of An Intervening Event - Two Acute Cellular Rejection Examples In Intestinal Transplantation

In testing the prognostic value of the occurrence of an intervening event (clinical event that occurs post-transplant), 3 proper statistical methodologies for testing its prognostic value exist (time dependent covariate, landmark, and semi-Markov modelling methods). However, time-dependent bias has appeared in many clinical reports, whereby the intervening event is statistically treated as a baseline variable (as if it occurred at transplant). Using a single-center cohort of 445 intestinal transplant cases to test the prognostic value of 1^st acute cellular rejection (ACR) and severe (grade of) ACR on the hazard rate of developing graft loss, we demonstrate how the inclusion of such time-dependent bias can lead to severe underestimation of the true hazard ratio (HR). The (statistically more powerful) time dependent covariate method in Cox's multivariable model yielded significantly unfavorable effects of 1^st ACR (P<.0001; HR=2.492) and severe ACR (P<.0001; HR=4.531). In contrast, when using the time-dependent biased approach, multivariable analysis yielded an incorrect conclusion for the prognostic value of 1^st ACR (P=.31, HR=0.877, 35.2% of 2.492) and a much smaller estimated effect of severe ACR (P=.0008; HR=1.589; 35.1% of 4.531). In conclusion, this study demonstrates the importance of avoiding time-dependent bias when testing the prognostic value of an intervening event.

Bridging Liver Transplantation in the Treatment of Intestinal Failure Associated Liver Disease in Infants-A Bridge Too Far?

Infants with intestinal failure associated liver disease (IFALD) requiring liver and bowel transplant have a high mortality on the transplant waiting list due to the scarcity of the size-matched donor organs. Bridging liver transplantation has been used to allow the children to grow to a reasonable size so that a combined liver and small bowel transplant could be performed in the future. We report on two children with irreversible intestinal failure (ultra-short bowel syndrome secondary to gastroschisis and microvillous inclusion disease) with IFALD who underwent bridging liver transplantation at our institution. Both patients made a good recovery from their initial surgery. One patient died 6 months following surgery from generalized sepsis, and the other patient survived in good condition to undergo a combined liver and small bowel transplant but died a few days post-transplant. In the current era of scarcity of donor organs, this raises an ethical dilemma for the team involved regarding appropriate utilisation of a scarce resource.

Current status of pediatric intestinal transplant in Europe

PURPOSE OF REVIEW

This review features articles published during 2018 and 2019 regarding pediatric visceral transplantation in Europe. In this biannual review, the authors identify and summarize key articles pertinent to clinical and research areas.

RECENT FINDINGS

There is a trend to a lower use of intestinal transplantation in pediatric population in Europe. Most articles were focused in long-term follow-up. The burden of the disease 10 years after intestinal transplantation is still significant, including the need of several medications, readmissions, and the need of specific follow-up, mostly because of psychiatric problems. Regarding eating behaviors, promoting eating pretransplant may be protective and there may be eating difficulty predictors that could be used to facilitate targeted interventions. Two different articles were consistent in the identification of C1q-fixing DSA as a marker of poor outcome, and capillaritis was identified as a predictor of C4d positivity in intestinal graft biopsies. The inclusion of the liver emerged as the main protective factor against dnDSA development. The incidence of PTLD (specially the monomorphic type) was significantly higher following ITx than after LTx (14.9 vs. 2.8%). The European societies and the EU have made an effort to promote networking, collaborative registries, and sharing of knowledge in pediatric transplantation.

SUMMARY

Recent articles focused mostly on long-term follow-up issues, although translational research has also been sustained by some groups.

Chronic Rejection After Intestinal Transplant: Where Are We in Order to Avert It?

Chronic rejection affects the long-term survival of all solid organ transplants and, among intestinal allografts, occurs in up to 10% of the recipients. The insidious clinical evolution of the chronic allograft enteropathy, the absence of noninvasive biomarkers, and the late endoscopic findings delay its diagnosis. No pharmacological approach has been proven effective, and allograft removal nowadays still represents the only available therapy. The inclusion of the liver in the visceral allograft appears to be the only intervention affecting the development of chronic rejection, as revealed by large-center studies and registry reports. A significant body of evidence emerged from the experimental setting and provided essential knowledge on the complex mechanisms behind the development of chronic allograft enteropathy. More recently, donor-specific antibodies have been suggested as an early, key element in the natural history of chronic allograft enteropathy and several novel approaches, tackling the antibody-mediated graft injury, have gained acceptance in clinical settings and are believed to impact on chronic rejection. The inclusion of a liver allograft is advocated when re-transplanting a sensitized recipient, due to its protective effect against humoral immunity. Multicenter trials are required to understand and tackle chronic rejection, and find the therapeutic answer to this clinical dilemma.

Pre-emptive Intestinal Transplant: The Surgeon's Point of View

Pre-emptive transplantation is a well-established practice for certain types of end-organ failure such as in the use of kidney transplantation. For irreversible intestinal failure, total parenteral nutrition (TPN) remains the gold standard, due to the suboptimal long-term results of intestinal transplantation. As such, the only role for pre-emptive transplantation, if at all, will be for patients identified to be at high risk of complications and mortality while on definitive long-term TPN. In these patients, the timing of early listing and transplantation could become life-saving, taking into account that mortality on the waiting list is still the highest for intestinal candidates. The development of simulation models or pre-transplant scoring systems could help in selecting patients based on potential outcome on TPN or with transplantation, and recent reports from high-volume centers identify few underlying pathologic conditions and some TPN complications as at higher risk of increased morbidity and mortality. A pre-emptive transplant could be used as a rehabilitative procedure in a well-selected case-by-case scenario, among TPN patients at risk of liver failure, repeated central line infections, mesenteric infarction, short bowel syndrome (SBS) <50 cm or with end stoma, congenital mucosal disease, desmoid tumors: These conditions must be carefully evaluated, not to underestimate the clinical stage nor to over-estimate the impact of a temporary situation. At the present time, diseases with a variable and unpredictable course, such as intestinal dysmotility disorders, or quality of life and financial issues are still far from being considered as indications for a pre-emptive transplant.

Pediatric parenteral nutrition-associated liver disease and cholestasis: Novel advances in pathomechanisms-based prevention and treatment

Parenteral nutrition constitutes a life-saving therapeutic tool in patients unable to ingest/absorb oral or enteral delivered nutrients. Liver function tests abnormalities are a common therapy-related complication, thus configuring the so-called Parenteral Nutrition Associated Liver Disease (PNALD) or cholestasis (PNAC). Although the damage is frequently mild, and resolves after discontinuation of parenteral nutrition, in some cases it progresses into cirrhotic changes, especially in neonates and infants. We present a literature review focusing on the pathogenetic mechanisms-driven prevention and therapies for the cases where parenteral nutrition cannot be discontinued. Ursodeoxycholic acid has been proposed in patients with cholestatic hepatopathy, but its efficacy needs to be better established. Little evidence is available on efficacy of anti-oxidants, antibiotics, probiotics and anti TNFα. Lipid emulsions based on fish oil with a high content of long-chain polyunsaturated fatty acids ω-3 appear effective both in decreasing intrahepatic inflammation and in improving biliary flow. Most recent promising variations such as soybean/MCT/olive/fish oil emulsion [third generation lipid emulsion (SMOFlipid)] are under investigation. In conclusion, we remark the emergence of a number of novel pathomechanisms underlying the severe liver impairment damage (PNALD and PNAC) in patients treated with parenteral nutrition. Only few traditional and innovative therapeutic strategies have hitherto been shown promising.

Lifor Solution: An Alternative Preservation Solution in Small Bowel Transplantation

Background and Objectives. The intestinal mucosa is extremely sensitive to ischemia. Better intestinal preservation is the first step to improve the results of intestinal transplantation. The aim of the study is to investigate the effect of cold Lifor solution on preservation of swine small bowel. Methods. Swine ileum segments (200 cm) were allotransplanted heterotopically after 9-hour cold storage with UW solution (group 1, n = 6), with Lifor solution (group 2, n = 6), or without storage (group 3, n = 6), respectively. After cold storage, mucosal adenosine triphosphate (ATP) concentrations and histopathologic analysis after preservation were performed. At day 7 after the transplantation, intestinal absorptive function was also observed. Results. After 9 h cold preservation, pathological changes, the content of ATP in the intestinal mucosa, and the intestinal absorptive function after transplantation in group 2 were similar to those of group 1. Conclusion. The effect of cold storage of swine small bowel with Lifor solution is similar to that of UW solution. It may provide additional rationale for further exploration of Lifor as an alternative preservation solution in small bowel transplantation.

Intestinal transplantation: The anesthesia perspective

Intestinal transplantation is a complex and challenging surgery. It is very effective for treating intestinal failure, especially for those patients who cannot tolerate parenteral nutrition nor have extensive abdominal disease. Chronic parental nutrition can induce intestinal failure associated liver disease (IFALD). According to United Network for Organ Sharing (UNOS) data, children with intestinal failure affected by liver disease secondary to parenteral nutrition have the highest mortality on a waiting list when compared with all candidates for solid organ transplantation. Intestinal transplant grafts can be isolated or combined with the liver/duodenum/pancreas. Organ Procurement and Transplantation Network (OPTN) has defined intestinal donor criteria. Living donor intestinal transplant (LDIT) has the advantages of optimal timing, short ischemia time and good human leukocyte antigen matching contributing to lower postoperative complications in the recipient. Thoracic epidurals provide excellent analgesia for the donors, as well as recipients. Recipient management can be challenging. Thrombosis and obstruction of venous access maybe common due to prolonged parenteral nutrition and/or hypercoaguability. Thromboelastography (TEG) is helpful for managing intraoperative product therapy or thrombosis. Large fluid shifts and electrolyte disturbances may occur due to massive blood loss, dehydration, third spacing etc. Intestinal grafts are susceptible to warm and cold ischemia and ischemia-reperfusion injury (IRI). Post-reperfusion syndrome is common. Cardiac or pulmonary clots can be monitored with transesophageal echocardiography (TEE) and treated with recombinant tissue plasminogen activator. Vasopressors maybe used to ensure stable hemodynamics. Post-intestinal transplant patients may need anesthesia for procedures such as biopsies for surveillance of rejection, bronchoscopy, endoscopy, postoperative hemorrhage, anastomotic leaks, thrombosis of grafts etc. Asepsis, drug interactions between anesthetic and immunosuppressive agents and venous access are some of the anesthetic considerations for this group.

Liver inclusion improves outcomes of intestinal retransplantation in adults. [Corrected]

BACKGROUND

Retransplantation is a viable treatment option for patients with primary intestinal graft loss.

METHODS

We analyzed outcomes of retransplantations (n = 23) in adults from May 2000 to May 2010 at our center and compared patients who received liver-free retransplantations (n = 13) with those who received liver-inclusive retransplantations (n = 10).

RESULTS

The overall survival rates at 1, 3, and 5 years in retransplantations were 90.9%, 67.1%, and 59.7% (patient) and 82.2%, 58.6%, and 51.3% (graft), respectively, which were similar to the rates in primary transplants. The patient survival rates at 1, 3, and 5 years were 91.7%, 55.6%, and 41.7%, respectively, in liver-free retransplantations, as compared to rates of 90.0%, 80.0%, and 80.0% in liver-inclusive retransplantations. The graft survival rates at 1, 3, and 5 years in liver-free retransplantations were 76.2%, 40.6%, and 27.1%, respectively, which were significantly worse than those in liver-inclusive retransplantations (P = 0.03). Within an average follow-up of 32.3 months, 8 of 13 (61.5%) of liver-free retransplantations underwent enterectomy because of severe acute cellular rejection (n = 3) or chronic rejection (n = 5). Six of 13 (46.2%) recipients succumbed to rejection-related complications. Compared to liver-free retransplantations, the rate and severity of acute rejection were markedly de creased in liver-inclusive retransplantations, and no chronic rejection was seen. Within an average follow-up of 44.5 months, two of 10 (20%) died due to graft-versus-host disease and infection, respectively.

CONCLUSION

A liver-inclusive retransplantation offers a better long-term patient and graft survival, suggesting that including the liver as part of an intestinal graft should be considered in adult recipients when retransplantation is necessary.

The natural history of cirrhosis from parenteral nutrition-associated liver disease after resolution of cholestasis with parenteral fish oil therapy

OBJECTIVE

To determine the natural history of cirrhosis from parenteral nutrition-associated liver disease (PNALD) after resolution of cholestasis with fish oil (FO) therapy.

BACKGROUND

Historically, cirrhosis from PNALD resulted in end-stage liver disease, often requiring transplantation for survival. With FO therapy, most children now experience resolution of cholestasis and rarely progress to end-stage liver disease. However, outcomes for cirrhosis after resolution of cholestasis are unknown and patients continue to be considered for liver/multivisceral transplantation.

METHODS

Prospectively collected data were reviewed for children with cirrhosis because of PNALD who had resolution of cholestasis after treatment with FO from 2004 to 2012. Outcomes evaluated included need for liver/multivisceral transplantation, mortality, and the clinical progression of liver disease.

RESULTS

Fifty-one patients with cirrhosis from PNALD were identified, with 76% demonstrating resolution of cholestasis after FO therapy. The mean direct bilirubin decreased from 6.4 ± 4 mg/dL to 0.2 ± 0.1 mg/dL (P < 0.001) 12 months after resolution of cholestasis, with a mean time to resolution of 74 days. None of the patients required transplantation or died from end-stage liver disease. Pediatric End-Stage Liver Disease scores decreased from 16 ± 4.6 to -1.2 ± 4.6, 12 months after resolution of cholestasis (P < 0.001). In children who remained PN-dependent, the Pediatric End-Stage Liver Disease score remained normal throughout the follow-up period.

CONCLUSIONS

Cirrhosis from PNALD may be stable rather than progressive once cholestasis resolves with FO therapy. Furthermore, these patients may not require transplantation and show no clinical evidence of liver disease progression, even when persistently PN-dependent.

Heterotaxy syndrome with malrotation of the gut and interrupted vena cava does not preclude safe procurement of multivisceral graft

We report the first successful procurement and transplantation of a multivisceral graft from a pediatric donor with polysplenic heterotaxy syndrome, including intestinal malrotation, midline liver with left-sided gallbladder and an interrupted inferior vena cava with azygous continuation. Procurement of the graft presented a surgical challenge in the presence of above anomalies. Modified approach to standard organ procurement and minor technical adaptation enabled successful transplantation. In an era of severe organ shortage of pediatric multivisceral grafts, a valuable organ offer should not lightly be declined for reasons of anatomic imperfections that might be overcome.