Pretransplant peritoneal dialysis and graft thrombosis following pediatric kidney transplantation: a NAPRTCS report

Pathophysiological Changes in the Hemostatic System and Antithrombotic Management in Kidney Transplant Recipients

Nowadays, the main cause for early graft loss is renal graft thrombosis because kidney transplant outcomes have improved drastically owing to advances in immunological techniques and immunosuppression. However, data regarding the efficacy of antithrombotic therapy in the prevention of renal graft thrombosis are scarce. Adequate antithrombotic management requires a good understanding of the pathophysiological changes in the hemostatic system in patients with end-stage kidney disease (ESKD). Specifically, ESKD and dialysis disrupt the fine balance between pro- and anticoagulation in the body, and further changes in the hemostatic system occur during kidney transplantation. Consequently, kidney transplant recipients paradoxically are at risk for both thrombosis and bleeding. This overview focuses on the pathophysiological changes in hemostasis in ESKD and kidney transplantation and provides a comprehensive summary of the current evidence for antithrombotic management in (adult) kidney transplant recipients.

The kidney allocation system and pediatric transplantation at 5 years

BACKGROUND

A new Kidney Allocation System (KAS) was implemented in the United States in 2014 with the goal of improving equity and utility.

METHODS

In this study, we compare outcomes for kidney-alone candidates less than 18 years of age, at the time of listing, in the 5 years prior to and following policy implementation using Organ Procurement and Transplantation Network data.

RESULTS

While the pediatric deceased donor transplant rate increased under KAS, this increase was due solely to improved access for children aged 11-17 years; there was an 18.9% decrease in the deceased donor transplant rate among children 0-5 years old, from 117.94 to 95.8 transplants per 100 person-years (p = .001). The cumulative incidence of deceased donor transplantation by 1 year after listing decreased from 39.3% in the pre-KAS era to 35.5% in the post-KAS era (p = .004), a decline that was driven entirely by longer wait times for children 0-5 years old (p = .017). Candidates with a calculated panel reactive antibody of 98%-100% experienced a significant increase in transplant rate, but there was no change in transplant rate for Black or Hispanic candidates.

CONCLUSION

Overall, KAS increased transplantation access for teenaged and highly sensitized candidates but resulted in decreased access for the youngest children with no improvement in racial/ethnic equality.

Pearls and Pitfalls in Pediatric Kidney Transplantation After 5 Decades

Worldwide, over 1,300 pediatric kidney transplantations are performed every year. Since the first transplantation in 1959, healthcare has evolved dramatically. Pre-emptive transplantations with grafts from living donors have become more common. Despite a subsequent improvement in graft survival, there are still challenges to face. This study attempts to summarize how our understanding of pediatric kidney transplantation has developed and improved since its beginnings, whilst also highlighting those areas where future research should concentrate in order to help resolve as yet unanswered questions. Existing literature was compared to our own data of 411 single-center pediatric kidney transplantations between 1968 and 2020, in order to find discrepancies and allow identification of future challenges. Important issues for future care are innovations in immunosuppressive medication, improving medication adherence, careful donor selection with regard to characteristics of both donor and recipient, improvement of surgical techniques and increased attention for lower urinary tract dysfunction and voiding behavior in all patients.

Surgical considerations in paediatric kidney transplantation: an update

Background

Kidney transplantation has established itself as the most appropriate mode of renal replacement therapy for the majority with end-stage kidney disease. Although at present this is applicable for children as well as adults, a few decades back kidney transplantation was not considered a first-line option in children. This was due to inferior outcomes following transplantation in this age group compared to that of adults. These poor results were attributed to challenges in paediatric transplantation such as the shortage of suitable donors, technical difficulties in performing a sound vascular anastomosis and the adverse effects of immunosuppressive medication on growth and development. However, current patient and graft-centred outcomes after paediatric transplantation equal or surpass that of adults. The advances in evaluation and management of specific surgical concerns in children who undergo transplantation, such as pre-transplant native nephrectomy, correction of congenital anomalies of the urinary tract, placement of an adult-sized kidney in a small child and minimizing the risk of allograft thrombosis, have contributed immensely for these remarkable outcomes.

Conclusions

In this review, we aim to discuss surgical factors that can be considered unique for children undergoing kidney transplantation. We believe that an updated knowledge on these issues will be invaluable for transplant clinicians, who are dealing with paediatric kidney transplantation.

Imaging of Renal Transplant Complications throughout the Life of the Allograft: Comprehensive Multimodality Review

The kidney is the most commonly transplanted solid organ. Advances in surgical techniques, immunosuppression regimens, surveillance imaging, and histopathologic diagnosis of rejection have allowed prolonged graft survival times. However, the demand for kidneys continues to outgrow the available supply, and there are efforts to increase use of donor kidneys with moderate- or high-risk profiles. This highlights the importance of evaluating the renal transplant patient in the context of both donor and recipient risk factors. Radiologists play an integral role within the multidisciplinary team in care of the transplant patient at every stage of the transplant process. In the immediate postoperative period, duplex US is the modality of choice for evaluating the renal allograft. It is useful for establishing a baseline examination for comparison at future surveillance imaging. In the setting of allograft dysfunction, advanced imaging techniques including MRI or contrast-enhanced US may be useful for providing a more specific diagnosis and excluding nonrejection causes of renal dysfunction. When a pathologic diagnosis is deemed necessary to guide therapy, US-guided biopsy is a relatively low-risk, safe procedure. The range of complications of renal transplantation can be organized temporally in relation to the time since surgery and/or according to disease categories, including immunologic (rejection), surgical or iatrogenic, vascular, urinary, infectious, and neoplastic complications. The unique heterotopic location of the renal allograft in the iliac fossa predisposes it to a specific set of complications. As imaging features of infection or malignancy may be nonspecific, awareness of the patient's risk profile and time since transplantation can be used to assign the probability of a certain diagnosis and thus guide more specific diagnostic workup. It is critical to understand variations in vascular anatomy, surgical technique, and independent donor and recipient risk factors to make an accurate diagnosis and initiate appropriate treatment.^©RSNA, 2019.

Renal allograft loss due to renal vascular thrombosis in the US pediatric renal transplantation

BACKGROUND

Renal vascular thrombosis (RVT) is a major cause of early allograft loss in the first year following pediatric kidney transplantation. We examined recent trends in allograft loss due to RVT and identified associated risk factors.

METHODS

We identified 14,640 kidney-only transplants performed between 1995 and 2014 with follow-up until June 30, 2016, in 13,758 pediatric patients aged < 19 years from the US Renal Data System. We examined the 1-year incidence of allograft loss due to RVT by year of transplant, and plotted the trend over time. Cox proportional hazards models were used to investigate the relationship between year of transplant as well as recipient, donor, and transplant characteristics with allograft loss due to RVT.

RESULTS

The incidence of allograft loss due to RVT consistently declined among pediatric kidney transplant performed between 1995 and 2014. Among transplants performed between 1995 and 2004, 128/7542 (1.7%) allografts were lost due to RVT compared to 53/7098 (0.8%) among transplants performed between 2005 and 2014; average 1-year cumulative incidence was 1.5% (95% CI, 1.3-1.9%) and 0.6% (95% CI, 0.5-0.8%), respectively. Increased risk for allograft loss due to RVT was associated with en bloc kidney transplantation (HR, 3.42; 95% CI 1.38-8.43) and cold ischemia time ≥ 12 h (HR, 1.78; 95% CI, 1.15-2.76). Interestingly, these risk factors were more prevalent in the latter decade.

CONCLUSIONS

The incidence of allograft loss due to RVT significantly and continuously declined among pediatric kidney transplants performed between 1995 and 2014. The causes for this improvement are unclear in the present analysis.

Surgical outcomes after pediatric kidney transplantation at the University of Heidelberg

BACKGROUND

Kidney transplantation (KTx) is the treatment of choice for children with end-stage renal disease (ESRD).

OBJECTIVE

An update of 48 years of surgical experience with pediatric KTx (PKTx) is presented, and the results between recipients of organs from deceased donors (DDs) and living donors (LDs) are compared.

STUDY DESIGN

All patients younger than 18 years who underwent KTx between 1967 and 2015 were evaluated. Data from 540 PKTx operations (409 DD and 131 LD) were obtained from the transplant center database. Peri-operative data and graft and patient survival were analyzed in the DD and LD groups.

RESULTS

Fewer recipients in the LD group underwent dialysis before PKTx than those in the DD group (50.8% in LD vs. 94.9% in DD, P < 0.001). The mean duration of dialysis (DD: 798 ± 525 days vs. LD: 625 ± 650 days, P = 0.03), time on the waiting list (DD: 472 ± 435 days vs. LD: 120 ± 243 days, P < 0.001), cold ischemia time (CIT) (DD: 1206 ± 368 min vs. LD: 140 ± 63 min, P < 0.001), operation time, and hospital stay were lower in the LD group. Except for arterial stenosis, the rates of postoperative vascular and urological complications were not different between the two groups. The cumulative 25-year graft and patient survival rates were 46.4% and 84.1% in the DD group and 76.5% and 96.1% in the LD group, respectively.

DISCUSSION

PKTx is the treatment of choice for children with ESRD. Graft quality has a direct impact on KTx outcome and rate of graft failure. Better HLA compatibility and shorter CIT reduce the impairment of graft function after LD PKTx. In addition, Establishment of an interdisciplinary approach using an individualized risk assessment and prevention model can improve PKTx outcomes.

CONCLUSION

Compared with DD PKTx, LD PKTx has better graft survival associated with a shorter duration of preceding dialysis, waiting time, and CIT and seems to be more beneficial for children.

Non-immunologic allograft loss in pediatric kidney transplant recipients

Non-immunologic risk factors are a major obstacle to realizing long-term improvements in kidney allograft survival. A standardized approach to assess donor quality has recently been introduced with the new kidney allocation system in the USA. Delayed graft function and surgical complications are important risk factors for both short- and long-term graft loss. Disease recurrence in the allograft remains a major cause of graft loss in those who fail to respond to therapy. Complications of over immunosuppression including opportunistic infections and malignancy continue to limit graft survival. Alternative immunosuppression strategies are under investigation to limit calcineurin inhibitor toxicity. Finally, recent studies have confirmed long-standing observations of the significant negative impact of a high-risk age window in late adolescence and young adulthood on long-term allograft survival.

Preemptively and non-preemptively transplanted patients show a comparable hypercoagulable state prior to kidney transplantation compared to living kidney donors

To prevent renal graft thrombosis in kidney transplantation, centres use different perioperative anticoagulant strategies, based on various risk factors. In our centre, patients transplanted preemptively are considered at increased risk of renal graft thrombosis compared to patients who are dialysis-dependent at time of transplantation. Therefore these patients are given a single dose of 5000 IU unfractionated heparin intraoperatively before clamping of the vessels. We questioned whether there is a difference in haemostatic state between preemptively and non-preemptively transplanted patients and whether the distinction in intraoperative heparin administration used in our center is justified. For this analysis, citrate samples of patients participating in the VAPOR-1 trial were used and several haemostatic and fibrinolytic parameters were measured in 29 preemptively and 28 non-preemptively transplanted patients and compared to 37 living kidney donors. Sample points were: induction anaesthesia (T1), 5 minutes after reperfusion (T2) and 2 hours postoperative (T3). At T1, recipient groups showed comparable elevated levels of platelet factor 4 (PF4, indicating platelet activation), prothrombin fragment F1+2 and D-dimer (indicating coagulation activation) and Von Willebrand Factor (indicating endothelial activation) compared to the donors. The Clot Lysis Time (CLT, a measure of fibrinolytic potential) was prolonged in both recipient groups compared to the donors. At T3, F1+2, PF4 and CLT were higher in non-preemptively transplanted recipients compared to preemptively transplanted recipients. Compared to donors, non-preemptive recipients showed a prolonged CLT, but comparable levels of PF4 and D-dimer. In conclusion pre-transplantation, preemptively and non-preemptively transplanted patients show a comparable enhanced haemostatic state. A distinction in intraoperative heparin administration between preemptive and non-preemptive transplantation does not seem justified.

Vascular thrombosis in pediatric kidney transplantation: Graft survival is possible with adequate management

OBJECTIVE

Vascular thrombosis (VT) in pediatric kidney transplantation (KT) is a dreaded event that leads to graft loss in almost 100% of cases. In recent years, VT has become the most common cause of early graft loss. The aim of this study was to analyze our experience in diagnosis and treatment of VT and the impact of a new management protocol on patient outcome.

METHODS

We conducted a retrospective study of 176 consecutive KT performed at our institution by the pediatric urology team between January 2000 and December 2015 and identified patients with VT. A protocol of prevention and early detection of VT was introduced in 2012.

RESULTS

Out of 176 KT, nine cases of VT were identified (5.1%). The mean recipient age was 5.1 years (SD 4.9 years) and mean weight was 22.28 kg (SD 15.6 kg). Diagnosis was intraoperative in two cases and within the first 24 h after surgery in the remaining seven. Immediate surgical exploration was performed after diagnosis in all. Of the five episodes that occurred before 2012, all developed complete graft ischemia requiring transplantectomy. However, in the four cases diagnosed after 2012, graft perfusion could be restored in three, and abdominal wall closure with a mesh and delayed sequentially closure under ultrasound guidance was performed. With a follow-up of 30, 25, and 20 months, the three recovered grafts are still functioning normally.

CONCLUSIONS

Increased awareness and the application of a protocol for prevention, detection and treatment of VT in pediatric KT can prevent graft loss. Immediate surgical intervention is mandatory after diagnosis. Avoiding compartment syndrome with delayed sequential closure may be useful to improve graft survival.

Outcome of renal transplantation in small infants: a match-controlled analysis

BACKGROUND

Infants with a body weight of less than 10 kg are often not considered to be suitable candidates for renal transplantation (RTx). The objective of this study was to evaluate this arbitrary weight threshold for pediatric RTx.

METHODS

We conducted a multicenter, retrospective, match-controlled cohort study on infants weighing less than 10 kg at time of engrafting (low-weight group [LWG], n = 38) compared to a matched control group (n = 76) with a body weight of 10-15 kg, using data from the first 2 years post-transplant derived from the CERTAIN Registry.

RESULTS

Patient survival was 97 and 100% in the LWG and control groups, respectively (P = 0.33), and death-censored graft survival was 100 and 95% in the LWG and control groups, respectively (P = 0.30). Estimated glomerular filtration rate at 2 years post-transplant was excellent and comparable between the groups (LWG 77.6 ± 34.9 mL/min/1.73 m²; control 74.8 ± 29.1 mL/min/1.73 m²; P = 0.68). The overall incidences of surgery-related complications (LWG 11%, control 23%; P = 0.12) and medical outcome measures (LWG 23%, control 36%, P = 0.17) were not significantly different between the groups. The medical outcome measures included transplant-related viral diseases (LWG 10%, control 21%; P = 0.20), acute rejection episodes (LWG 14%, control 29%; P = 0.092), malignancies (LWG 3%, control 0%; P = 0.33) and arterial hypertension (LWG 73%, control 67%; P = 0.57).

CONCLUSIONS

These data suggest that RTx in low-weight children is a feasible option, at least in selected centers with appropriate surgical and medical expertise.

Vascular Complications After Renal Transplant: A Single-Center Experience

OBJECTIVES

Despite surgical and medical advances, vascular complications are still among the major concerns after renal transplant, with a reported incidence of 3% to 15%. We evaluated the incidence and management of our transplant team 's vascular complications over 40 years.

MATERIALS AND METHODS

From November 1975 to the present, we have performed a total of 2594 renal transplant procedures. Of these, 1997 grafts (76%) were obtained from living donors, and 597 grafts (24%) were obtained from deceased donors. All renal transplant procedures, including those performed in pediatric patients, used the extraperitoneal approach to the contralateral iliac fossa. Revascularization was performed for all grafts. A single end-to-end internal iliac artery anastomosis was performed in 1082 patients (41.8%), an end-to-side external iliac artery anastomosis was performed in 1289 patients (49.7%), and an end-to-side common iliac artery anastomosis was performed in 66 patients (2.5%). In 157 procedures (6%), there were at least 2 renal arteries, and both internal iliac arteries or external iliac arteries were used for anastomosis.

RESULTS

We observed 57 vascular complications (2.1%) in 54 renal transplant procedures. The most frequent complication was renal artery stenosis (n = 17; 0.6%). There were 8 instances of renal artery thrombosis (0.4%), 7 of renal artery kinking (0.3%), 5 of renal vein thrombosis (0.2%), 9 of renal vein kinking (0.5%), 3 of external iliac artery dissection (0.01%), 5 renal vein lacerations (0.2%), and 3 renal artery lacerations (0.01%). We performed urgent surgery for 41 vascular complications; 38 were managed successfully. Percutaneous interventional techniques were used successfully for 18 vascular complications.

CONCLUSIONS

The vascular complication rate in our patients is lower than that reported in the literature. Surgical complications can be minimized with careful transplant technique and close follow-up, as early diagnosis is crucial to early management and successful treatment of complications.

Surgical Complications After Kidney Transplantation

Since the first successful organ transplant conducted between twins in 1954, kidney transplant has evolved considerably over the past 50 years. Kidney transplant plays an important role in the treatment of end-stage kidney disease to improve the quality of life and prolong the life of patients. Despite significant advances, postoperative medical and surgical complications still represent important causes of morbidity and mortality. Many problems can be avoided through prophylactic correction of abnormalities detected during the preoperative evaluation; however, it is critical that technical mishaps at all stages of the transplant process (donor nephrectomy, benchwork preparation, and implant) be prevented and that careful postoperative monitoring be carried out, including thorough examination by attending physicians. However, despite these advances, surgical complications still present serious problems in kidney transplant recipients.

Thrombosis of the Abdominal Veins in Childhood

Abdominal venous thrombosis is a rare form of venous thromboembolic disease in children. While mortality rates are low, a significant proportion of affected children may suffer long-term morbidity. Additionally, given the infrequency of these thrombi, there is lack of stringent research data and evidence-based treatment guidelines. Nonetheless, pediatric hematologists and other subspecialists are likely to encounter these problems in practice. This review is therefore intended to provide a useful guide on the clinical diagnosis and management of children with these rare forms of venous thromboembolic disease. Herein, we will thus appraise the current knowledge regarding major forms of abdominal venous thrombosis in children. The discussion will focus on the epidemiology, presentation, diagnosis, management, and outcomes of (1) inferior vena cava, (2) portal, (3) mesenteric, (4) hepatic, and (5) renal vein thrombosis.

Pre-transplant dialysis modality does not influence short- or long-term outcome in kidney transplant recipients: analysis of paired kidneys from the same deceased donor

Previous studies have reported contradictory results regarding the effect of pre-transplant dialysis modality on the outcomes after kidney transplantation (KT). To minimize the confounding effect of donor-related variables, we performed a donor-matched retrospective comparison of 160 patients that received only one modality of pre-transplant dialysis (peritoneal dialysis [PD] and hemodialysis [HD] in 80 patients each) and that subsequently underwent KT at our center between January 1990 and December 2007. Cox regression models were used to evaluate the association between pre-transplant dialysis modality and primary study outcomes (death-censored graft survival and patient survival). To control for imbalances in recipient-related baseline characteristics, we performed additional adjustments for the propensity score (PS) for receiving pre-transplant PD (versus HD). There were no significant differences according to pre-transplant dialysis modality in death-censored graft survival (PS-adjusted hazard ratio [aHR]: 0.65; 95% confidence interval [95% CI]: 0.25-1.68) or patient survival (aHR: 0.58; 95% CI: 0.13-2.68). There were no differences in 10-year graft function or in the incidence of post-transplant complications either, except for a higher risk of lymphocele in patients undergoing PD (odds ratio: 4.31; 95% CI: 1.15-16.21). In conclusion, pre-transplant dialysis modality in KT recipients does not impact short- or long-term graft outcomes or patient survival.

Renal transplantation in infants

Renal transplantation (RTx) has become an accepted mode of therapy in infants with severe renal failure. The major indications are structural abnormalities of the urinary tract, congenital nephrotic syndrome, polycystic diseases, and neonatal kidney injury. Assessment of these infants needs expertise and time as well as active treatment before RTx to ensure optimal growth and development, and to avoid complications that could lead to permanent neurological defects. RTx can be performed already in infants weighing around 5 kg, but most operations occur in infants with a weight of 10 kg or more. Perioperative management focuses on adequate perfusion of the allograft and avoidance of thrombotic and other surgical complications. Important long-term issues include rejections, infections, graft function, growth, bone health, metabolic problems, neurocognitive development, adherence to medication, pubertal maturation, and quality of life. The overall outcome of infant RTx has dramatically improved, with long-term patient and graft survivals of over 90 and 80 %, respectively.

Renal transplantation experience in a patient with factor V Leiden homozygous, MTHFR C677T heterozygous, and PAI heterozygous mutation

Vascular complications are important causes of allograft loss in renal transplantation. A two and a half-month-old boy was diagnosed with posterior urethral valve and progressed to end-stage renal disease at eight yr of age. During the HD period, a central venous catheter was replaced three times for repeated thrombosis. The boy was found to be homozygous for FVL and heterozygous for both MTHFR (C677T) and PAI. At the age of 12, renal transplantation was performed from a deceased donor. Postoperative anticoagulation therapy was initiated with continuous intravenous administration of heparin at the dose of 10 IU/kg/h. HD was performed for the first three days. By the fourth day of transplantation, his urine output had increased gradually. Heparin infusion was continued for 18 days during hospitalization at the same dosage. Thereafter, he was discharged with LMWH. On the third month after transplantation, his serum creatinine level was 1.1 mg/dL and eGFR was 75.7 mL/min/1.73 m(2). He has still been using LMWH, and his eGFR was 78.7 mL/min/1.73 m(2) eight months after transplantation. Postoperative low-dose heparin treatment is a safe strategy for managing a patient with multiple thrombotic risk factors.

Pediatric transplantation: preventing thrombosis

Due to progressive advances in surgical techniques, immunosuppressive therapies, and supportive care, outcomes from both solid organ transplantation and hematopoietic stem cell transplantation continue to improve. Thrombosis remains a challenging management issue in this context, with implications for both graft survival and long-term quality of life. Unfortunately, there remains a general paucity of pediatric-specific data regarding thrombosis incidence, risk stratification, and the safety or efficacy of preventative strategies with which to guide treatment algorithms. This review summarizes the available evidence and rationale underlying the spectrum of current practices aimed at preventing thrombosis in the transplant recipient, with a particular focus on risk factors, pathophysiology, and described antithrombotic regimens.

Healthcare burden of venous thromboembolism in childhood chronic renal diseases

BACKGROUND

Chronic renal diseases (CRD) are associated with approximately 5% of pediatric venous thromboembolism (VTE) cases, but the epidemiology of VTE in CRD is ill-defined.

METHODS

Children (<18 years) with CRD were identified from MarketScan® Research databases. The VTE status of subjects with CRD who qualified for this study was ascertained during the 6 months following the initial diagnosis of CRD. Demographics, healthcare utilization, mortality, and co-morbid conditions were assessed.

RESULTS

A total of 22,877 children with predefined CRD ICD-9-CM codes were identified between April 1, 2003 and June 30, 2012, among whom 0.55% had VTE. Our analysis revealed that in-hospital mortality was more likely in children with VTE than in those without VTE (11.9 vs. 0.9%, respectively; p < 0.0001). The usage of healthcare facilities, based on the number of inpatient admissions, length of stay, outpatient visits, and pharmaceutical claims, was also significantly higher in patients with VTE than in those without (p < 0.0001). Total mean healthcare expenditures for the 6-month follow-up period were 13-fold greater in the VTE group than in the group without VTE ($338,338 ± $544,045 vs. $25,171 ± $90,792; p < 0.0001). In a multivariate model, infection, hemodialysis, and trauma/surgery significantly increased the likelihood of VTE.

CONCLUSIONS

Venous thromboembolism is rare in children with CRD, but it is associated with higher mortality and healthcare utilization when present. Among the children with CRD enrolled in our study, the likelihood of VTE was increased among those with co-morbid, non-renal chronic conditions.

Near-infrared spectroscopy as continuous real-time monitoring for kidney graft perfusion

BACKGROUND

Near-infrared spectroscopy (NIRS) is a non-invasive technique designed to study regional oxygenation (rSO(2)) by measuring the absorption of chromophores. This study investigated the role of NIRS in the real-time monitoring of kidney graft perfusion for 72 h post-transplantation.

METHODS

Consecutive children undergoing living related donor (LRD) or deceased donor (DD) kidney transplantation (KTP) were prospectively enrolled between April 2010 and August 2011. Renal rSO(2) values were registered continuously for 3 days and correlated with hourly urine output, serum creatinine, and urinary neutrophil gelatinase-associated lipocalin (u-NGAL).

RESULTS

Twenty-four children were included, 6 underwent LRD and 18 DD KTP. Median age was 12.5 years (interquartile range [IQR] 3.5-16.6) and median body weight was 37 kg (IQR 13-49.7). Four patients experienced delayed graft function (DGF). Renal Doppler ultrasound showed normal vascularization patterns in all children. Median basal renal rSO(2) value was 68.8 % (IQR 59.3-76.2), significantly lower than the end-of-period result (83.6 %; IQR 79.2-90.4; p < 0.0001). Renal rSO(2) values showed significant correlation with serum creatinine (rs = -0.62; p < 0.05) and estimated glomerular filtration rate (eGFR) (rs = 0.64; p < 0.05). No correlation was shown between rSO(2) and diuresis. Increased rSO(2) was also found in patients who experienced DGF. u-NGAL exhibited a trend toward a decrease from baseline in both DD and LRD KTPs, with a strong negative correlation with rSO(2).

CONCLUSIONS

rSO(2) assessed by NIRS strongly correlates with common markers of kidney graft function and perfusion, allowing continuous real-time monitoring of blood flow in renal grafts.

Identification of risk factors for vascular thrombosis may reduce early renal graft loss: a review of recent literature

Renal graft survival has improved over the past years, mainly owing to better immunosuppression. Vascular thrombosis, though rare, therefore accounts for up to one third of early graft loss. We assess current literature on transplantation, identify thrombosis risk factors, and discuss means of avoiding thrombotic events and saving thrombosed grafts. The incidence of arterial thrombosis was reported to 0.2–7.5% and venous thrombosis 0.1–8.2%, with the highest incidence among children and infants, and the lowest in living donor reports. The most significant risk factors for developing thrombosis were donor-age below 6 or above 60 years, or recipient-age below 5-6 years, per- or postoperative hemodynamic instability, peritoneal dialysis, diabetic nephropathy, a history of thrombosis, deceased donor, or >24 hours cold ischemia. Multiple arteries were not a risk factor, and a right kidney graft was most often reported not to be. Given the thrombosed kidney graft is diagnosed in time, salvage is possible by urgent reoperation and thrombectomy. Despite meticulous attentions to reduce thrombotic risk factors, thrombosis cannot be entirely prevented and means to an early detection of this complication is desirable in order to save the kidneys through prompt reoperation. Microdialysis may be a new tool for this.

[Outcomes of pediatric renal transplantation in France]

Significant progress has been observed in pediatric renal transplantation over the last 20 years, leading to an increase in graft and patient survival. Mortality is low and is mainly due to infections, neoplasias and complications related to the initial disease. Graft survival is 67% at 10 years. Factors which influence graft survival are: donor type (results are better with a live donor), donor age, recipient age (with 2 periods at risk:<2 years old and teenagers), HLA incompatibilities, and recurrence of the initial disease. Chronic allograft nephropathy (CAN) is the major cause of late graft loss. Poor compliance, especially in teenagers, may lead to late rejections and graft loss. Calcineurin inhibitors nephrotoxicity is in part responsible for the development of CAN, thus treatments and the role of mTOR inhibitors will probably evolve. These different factors are discussed in this article.

Follow-up of patients with juvenile nephronophthisis after renal transplantation: a single center experience

BACKGROUND

Nephronophthisis (NPHP) is the most common genetic cause of end-stage renal disease (ESRD) in the first 3 decades of life. Treatment of patients with NPHP is symptomatic; kidney transplantation is the treatment of choice when ESRD is established. We report herein our center's experience with kidney transplantation for children with juvenile NPHP.

PATIENTS

We retrospectively analyzed medical records of 9 renal transplant recipients with a primary diagnosis of juvenile NPHP confirmed by genetic analysis and/or renal biopsy findings in a single center from 1996 to 2010.

RESULTS

Of the 9 patients, 6 received a living related and 3 a cadaveric donor transplantation. Preemptive renal transplantation was performed in 7 patients. The median age of the patients was 13.38 ± 4.6 years; the median follow-up period was 17 months. Posttransplantation immusuppression comprised corticosteroids, a calcineurin inhibitor, and mycophenolate mofetil or azathioprine. One patient lost his renal graft owing to renal graft thrombosis, and grade II chronic allograft nephropathy was diagnosed by renal biopsy on the 62th day after renal transplantation in another patient. The median glomerular filtration rates after transplantation at 1, 3, and 5 years were 85, 75.2, and 83.2 mL/min/1.73 m(2), respectively.

CONCLUSION

We observed preserved graft functions for long periods among renal transplant recipients with juvenile NPHP. Chronic allograft nephropathy developed rarely on long follow-up.

Kidney transplantation and donation in children

It has been shown that kidney transplantation results in superior life expectancy and quality of life compared with dialysis treatment for patients with end-stage renal disease. However, kidney transplantation in children differs in many aspects from adult kidney transplantation. This review focuses on specific issues of surgical care associated with kidney transplantation in children, including timing of transplantation, technical considerations, patient and graft survival, growth retardation and post-transplant malignancy. At the same time, there is a large discrepancy between the number of available donor kidneys and the number of patients on the waiting list for kidney transplantation. There is a general reluctance to use paediatric donor kidneys, because of relatively frequent complications such as graft thrombosis and early graft failure. We review the specific aspects of kidney transplantation from paediatric donors such as the incidence of graft thrombosis, hyperfiltration injury and 'en bloc' transplantation of two kidneys from one donor with an excellent long-term outcome, which is comparable with adult donor kidney transplantation. We also discuss the potential use of paediatric non-heart-beating donor kidneys, from donors whose heart stopped beating with the preservation techniques used.

Right atrial thrombosis complicating renal transplantation in a child

Nephrotic syndrome represents a form of acquired thrombophilia thereby causing increased risk of thrombosis. In patients with nephrotic syndrome both venous and arterial thrombosis can occur; however, intracardiac thrombus is among the rarest reported in the literature. In this case report, we present a 10.5-yr-old boy with right atrial thrombosis and an acute rejection episode after renal transplantation due to end stage renal disease caused by focal segmental glomerulosclerosis manifested by nephrotic syndrome. The clinical course was successfully managed with surgical removal of thrombus, institution of anticoagulant as well as antirejection therapy. This report draws attention to the risks that could be associated with thrombosis in renal recipients with congenital or acquired thrombophilias and emphasizes the importance of identifying risk factors for thrombosis in these patients.

Contributions of the Transplant Registry: The 2006 Annual Report of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS)

This summary of the NAPRTCS 2006 Annual Report of the Transplant Registry highlights the significant impact the registry has had in advancing knowledge in pediatric renal transplantation worldwide. This cooperative group has collected clinical information on children undergoing a renal transplantation since 1987 and now includes over 150 participating medical centers in the USA, Canada, Mexico, and Costa Rica. Currently, the NAPRTCS transplant registry includes information on 9837 renal transplants in 8990 patients (NAPRTCS 2006 Annual Report). Since the first data analysis in 1989, NAPRTCS reports have documented marked improvements in outcome after renal transplantation in addition to identifying factors associated with both favorable and poor outcomes. The registry has served to document and influence practice patterns, clinical outcomes, and changing trends in renal transplantation.

The anesthetic management of a child with chronic hypotension for renal transplantation

The anesthetic management of renal transplant recipients requires the maintenance of an adequate perfusion pressure to ensure viability of the donated kidney. A common finding among patients with end-stage renal disease is chronic hypertension. We report a case involving a 2-year-old child with an age-adjusted blood pressure below normal, undergoing transplantation of an adult cadaveric kidney, during which high-dose vasopressor medications were used to sustain the child's blood pressure at above-normal levels to help ensure perfusion of the adult allograft.

Rabbit antithymocyte globulin related decrease in platelet count reduced risk of pediatric renal transplant graft thrombosis

Graft thrombosis is a serious complication in pediatric renal transplantation. We assess a potential protective effect for the decrease in platelet count associated with RATG therapy against pediatric renal transplant graft vascular thrombosis. Between January 1986 and December 1998, 120 kidney transplants were performed in 95 pediatric recipients. Patients were divided into two groups. Group 1 (n = 61), non-RATG group received cyclosporine, azathioprine and steroids, while group 2 (n = 59), RATG group, received in addition, RATG at day 1 and continued for 4-10 days postoperatively. Platelet count prior to transplant, median change in absolute platelet count at 1 and 3 days post-transplant was recorded. Graft thrombosis incidence was examined. Six grafts (5%) developed thrombosis. All were in group 1 (p = 0.028). Median pretransplant platelet count (x10(9)/L) in group 1 was 283 vs. 280 in group 2 (p = 0.921). Median decrease in absolute platelet count (x10(9)/L) from pretransplant levels at one and three days post-transplant for group 1 and 2 was 18 vs. 83 (p </= 0.001) and 39 vs. 105 (p </= 0.001), respectively. Graft thrombosis risk factors were similar in both groups. RATG use was statistically significant (p = 0.044) for reduced risk of graft thrombosis in multivariate analysis. Patients receiving RATG showed significant decrease in both platelet count and graft thrombosis incidence. A role for RATG related effect on platelet count is assumed.

Outcome after kidney transplantation in children with thrombotic risk factors

BACKGROUND

According to the data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS), vascular thrombosis accounts for 11.6% of graft losses in pediatric renal transplantation. In adults, inherited and acquired thrombophilic risk factors, e.g. factor V Leiden mutation, have been associated with early graft loss and increased rejection episodes. Data on the impact of these factors on the outcome of children after renal transplantation are rare.

METHODS/PATIENTS

Sixty-six pediatric patients awaiting renal transplantation (mean age 10.1 yr) were screened for inherited and acquired risk factors for hypercoagulable disorders (protein C, S, and antithrombin III deficiency, antiphospholipid antibodies, factor V Leiden, prothrombin, and MTHFR mutation) in order to intensify anticoagulation in those with an increased risk for thrombophilia: intravenous heparin was administered with a partial prothrombin time (PTT) prolongation of 50 s for 14 days and switched to low-molecular-weight heparin for another 8 wk before aspirin was introduced for the first year. Patients without hypercoagulable risk factors were treated with heparin without PTT prolongation for 14 days and switched to aspirin immediately afterwards. The results on graft survival, incidence of acute rejection episodes, and long-term renal graft function were analyzed between recipients with and without hypercoagulable risk factors.

RESULTS

Thrombophilic risk factors were identified in 27.3% of our patients. No thrombosis occurred. One serious bleeding complication led to a second surgical intervention. The rate of acute rejection episodes was not increased in patients with and without thrombotic risk factors after 90 days (16.7 vs. 25%), 1 yr (22.2 vs. 33.3%), and 3 yr (38.9 vs. 41.7%) of follow-up, respectively (p = n.s.). After a mean follow-up of 3 yr the kidney function was comparable in both groups, with 63.1 in recipients with and 69.8 mL/min/1.73 m(2) in recipients without hypercoagulable risk (p = n.s.). At latest follow-up, three graft losses were found not to be attributed to thrombotic risk factors.

INTERPRETATION

Children with thrombophilic risk factors were identified and treated with an intensified anticoagulation regimen after renal transplantation. An increased risk for graft failure, acute rejection episodes, or impaired renal function for pediatric renal transplant recipients with hypercoagulable status was not found.

Decreased risk of renal allograft thrombosis associated with interleukin-2 receptor antagonists: a report of the NAPRTCS

Graft thrombosis is the most common cause of first year graft failure in pediatric renal transplantation. The North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) database was analyzed for cases of graft failure due to thrombosis among patients transplanted from 1998 to 2004. The impact of interleukin-2 (IL-2) receptor antagonists as induction therapy was determined. There were a total of 51 graft failures due to thrombosis among the 2750 reported renal transplants (1.85%) (95% CI (1.39%, 2.41%)). This represents the most common cause of graft loss during the first year post-transplant accounting for 35% of first year losses and 18% of all graft losses. The incidence of thrombosis among patients who received IL-2 receptor antibodies was 1.07% (12/1126) compared to 2.40% (39/1624) among patients who did not (OR 0.44, 95% CI 0.23, 0.84, p = 0.014). Use of IL-2 receptor blockade was the only significant prognostic factor in a multivariate model with previously identified risk factors. Analysis of NAPRTCS data found that the use of IL-2 receptor antibodies as induction therapy is associated with a significantly decreased risk of graft failure due to thrombosis. This provocative finding requires further investigation to determine whether thrombotic failure can be decreased by this therapeutic strategy.

Successful renal transplantation in a patient with heterozygous prothrombin gene, factor V Leiden mutation and heparin-induced thrombocytopenia using r-hirudin as anticoagulant

Vascular complications remain the most common cause of early renal allograft loss in patients with end-stage renal failure. Underlying thrombophilic disorders increase the risk of early graft thrombosis. A male adolescent with high-risk thrombophilia because of combined heterozygous factor V Leiden (G1691A) and prothrombin gene (G20210A) mutation developed HIT II. Hemodialysis and subsequent renal transplantation were undertaken using recombinant hirudin, a direct and selective thrombin inhibitor, as an anticoagulant. Primary function in the transplanted kidney was excellent. No thrombotic or hemorrhagic events have occurred and follow-up showed excellent long-term graft survival. Patients on HD have an increased risk for the development of HIT, and therefore, they need repetitive screening for the development of acquired thrombotic risk factors (e.g. HIT II or lupus anticoagulant). R-hirudin is efficacious and safe on both HD and following renal transplantation.

RABBIT ANTITHYMOCYTE GLOBULIN AS INDUCTION IMMUNOTHERAPY FOR PEDIATRIC DECEASED DONOR KIDNEY TRANSPLANTATION

PURPOSE

There is scant literature describing the long-term outcome of the use of antithymocyte globulin induction immunotherapy in pediatric deceased donor kidney transplants. We retrospectively studied the long-term results and safety of antithymocyte globulin as induction immunotherapy in all children undergoing transplantation at our institution since 1991.

MATERIALS AND METHODS

A total of 120 kidney transplants were performed in 95 patients 18 years or younger between January 1986 and December 1998. Patients were divided into 2 groups. The control group (63 patients) received cyclosporine, azathioprine and prednisolone, while the treatment group (59 patients) received rabbit antithymocyte globulin (RATG) induction immunotherapy for 6 to 10 days, combined with cyclosporine, azathioprine and prednisolone.

RESULTS

Actuarial patient survival rates at 1, 3, 5 and 10 years were 96%, 95%, 95% and 90%, respectively. Actuarial graft survival rates at 1, 3, 5 and 10 years were 76%, 69%, 64% and 49%, respectively. The 1, 3, 5 and 10-year graft survival rates in the control group were 62%, 57%, 51% and 36%, respectively, compared to 90%, 82%, 79% and 69%, respectively, in the RATG group (p = 0.001). There was a significant difference in the incidence of graft loss secondary to acute cellular rejection between the control and RATG groups (19.7% vs 3.3%, p = 0.008). There was no difference in infectious complications between the control and RATG groups (13% vs 20%, p = 0.33), and there was no case of post-transplant lymphoproliferative disorder encountered in either group.

CONCLUSIONS

The use of rabbit antithymocyte globulin in pediatric deceased donor kidney transplant recipients resulted in significant improvement in graft survival and was relatively safe.

Access to, and outcome of, renal transplantation according to treatment modality of end-stage renal disease in France

BACKGROUND

Although peritoneal dialysis (PD) is recognized as one of the methods of treatment of end-stage renal disease (ESRD), there have been recurrent concerns about the access of patients treated by this modality to kidney transplantation (KTx), as well as reports showing increased complications of KTx in such patients, such as graft thrombosis and infections.

METHODS

The aim of this study was to provide a comprehensive view of the impact on transplantation of pretransplant modality of treatment of ESRD using a multivariate analysis of the French database. From 1997 to 2000, after exclusion of pediatric patients, multiple transplantations, and living donors, 6420 were patients registered on the waiting list, and 3464 were transplanted.

RESULTS

Using a Cox proportional hazard analysis, we found a shorter waiting time for PD patients (RR 0.71, P < 0.0001), which became equivalent to hemodialysis (HD) patients when taking into account the transplant center as a variable (RR 1.0, P= 0.95). Concerning graft survival, only preemptive transplantation had a significant impact, being associated to a decreased risk of graft failure (RR 0.46, P= 0.005). Conclusion. Our study supports the concept that the choice of any pretransplant dialysis modality does not influence waiting time for transplant or the results of transplantation.

Epidemiology of venous thromboembolism in neonates and children

Venous thromboembolism is an increasingly recognised problem in paediatric practice, particularly in the context of tertiary care paediatric services. In recent years, several national and international registries have helped to define the epidemiology of venous thromboembolism in both neonates and older children. These studies have generated information on the incidence and risk factors associated with venous thromboembolism in different age groups. Data from these and other studies have demonstrated important differences between paediatric and adult practice and highlight the need for specific evidence based guidelines for the prevention and management of venous thromboembolism in neonates and children.

Obesity and renal transplant outcome: a report of the North American Pediatric Renal Transplant Cooperative Study

OBJECTIVE

Obesity is increasing in the end-stage renal disease population. Studies that have evaluated the effect of obesity on transplant outcomes in adults have yielded varying results. This issue has received little attention in the pediatric population.

METHODS

We performed a retrospective study of the effect of obesity on pediatric renal transplant outcomes using the North American Pediatric Renal Transplant Cooperative Study database. Registry data from 1987 through 2002 on 6658 children aged 2 to 17 years were analyzed. Obesity was defined by a BMI >95th percentile for age.

RESULTS

Overall, 9.7% were obese with an increase noted in recent years (12.4% after 1995 vs 8% before 1995). Obese children were significantly younger and shorter and had been on dialysis for a longer time than nonobese children. There was no significant difference in the overall patient and allograft survival between the 2 groups. However, obese children aged 6 to 12 years had higher risk for death than nonobese patients (adjusted relative risk: 3.65 for living donor; adjusted relative risk: 2.94 for cadaver), and death was more likely as a result of cardiopulmonary disease (27% in obese vs 17% in nonobese). Overall, graft loss as a result of thrombosis was more common in obese as compared with nonobese (19% vs 10%).

CONCLUSIONS

Obesity is an increasing problem in children who present for transplantation and may have an adverse effect on allograft and patient survival.

Pediatric transplantation

Analysis of the OPTN/SRTR database demonstrates that, in 2002, pediatric recipients accounted for 7% of all recipients, while pediatric individuals accounted for 14% of deceased organ donors. For children fortunate enough to receive a transplant, there has been continued improvement in outcomes following all forms of transplantation. Current 1-year graft survival is generally excellent, with survival rates following transplantation in many cases equaling or exceeding those of all other recipients. In renal transplantation, despite excellent early graft survival, there is evidence that long-term graft survival for adolescent recipients is well below that of other recipients. A causative role for noncompliance is possible. While the significant improvements in graft and patient survival are laudable, waiting list mortality remains excessive. Pediatric candidates awaiting liver, intestine, and thoracic transplantation face mortality rates generally greater than those of their adult counterparts. This finding is particularly pronounced in patients aged 5 years and younger. While mortality awaiting transplantation is an important consideration in refining organ allocation strategies, it is important to realize that other issues, in addition to mortality, are critical for children. Consideration of the impact of end-stage organ disease on growth and development is often equally important, both while awaiting and after transplantation.