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

Pediatric kidney transplantation: is it safe to perform during night-time or day-off?

PURPOSE

To investigate the impact of after-hours surgery on the outcomes of pediatric kidney transplantation (KT).

METHODS

Medical records of pediatric KTs performed at a single institution between 2013 and 2021 were retrospectively reviewed. The population was split into three groups according to the incision time and calendar: ordinary day (8.00 AM - 6.30 PM), day-off, and night-time (6.30 PM - 8.00 AM). The following endpoints were compared: ischemia times, length of surgery, complications, delayed graft function (DGF), primary graft non-function (PGNF), and eGFR at three-month follow-up.

RESULTS

Ninety-six non-living donor KTs were performed, median age 11 (IQR 4.3-14) years and median body weight 26 (IQR 13-50) kg. Forty-one (43%) were performed during night-time and 28 (29%) during day-off. Ischemia times were similar (p = 0.769, p = 0.536). Day-off KTs presented an extended length of surgery (p = 0.011). Thirty-two complications were reported in 31 KTs. No difference in the overall rate of complications, DGF, PNGF, and three-month eGFR was found (p = 0.669, p = 0.383, p = 0.949, p = 0.093). Post-operative bleedings were more common in days-off (p = 0.003).

CONCLUSION

The number of pediatric KTs performed during after-hours was considerable. Even though similar outcomes were reported, more caution should be focused on the KTs performed in days-off to avoid severe complications.

Changes in graft outcomes in recipients <10 kg over 25 years of pediatric kidney transplantation in the United States

BACKGROUND

Kidney transplant (KT) was initially associated with poor outcomes, especially in smaller recipients. However, pediatric transplantation has evolved considerably over time. We investigated the impact of weight at the time of transplant and whether outcomes changed over 25 years for <10 kg recipients.

METHODS

Using the UNOS database, pediatric recipient outcomes were analyzed between 1/1/99 and 12/31/14. KT weight was stratified: <8.6 kg (mean weight of recipients <10 kg), 8.6-9.9 kg, 10-14.9 kg, 15-29.9 kg, and ≥30 kg. Outcomes in recipients <10 kg were then compared between 1990-1999 and 2000-2014.

RESULTS

17 314 pediatric KT recipients were included; 518 (3%) had a transplant weight <10 kg. The highest rates of allograft loss and death were in recipients <8.6 kg and ≥30 kg. Recipients <8.6 kg also had higher rates of delayed graft function, rejection, and longer hospital length of stay. In the multivariable Cox regression model, transplant weight was not a predictor of allograft loss. When compared with recipients <8.6 kg, patient survival hazard ratios associated with recipient weight of 10-14.9 kg, 15-29.9 kg, and ≥30 kg were 0.61 (95%CI: 0.4, 1), 0.42 (95%CI: 0.3, 0.7) and 0.32 (95%CI: 0.2, 0.6), respectively. In the later era of transplant, recipients <10 kg had improved outcomes on univariate analysis; however, the era of transplantation was not an independent predictor of allograft loss or patient survival in Cox regression models.

CONCLUSIONS

Outcomes in children weighing 8.6-9.9 kg at the time of KT were similar to higher weight groups and improved over time; however, special precautions should be taken for recipients <8.6 kg at the time of transplant.

The Outcome of Transplanting Kidneys From Very Small Pediatric Deceased Donors

BACKGROUND

Kidneys from very small pediatric donors (VSPDs, aged <2 y) are underutilized. Concerns regarding potentially inferior outcomes hinder the use in pediatric recipients.

METHODS

All pediatric kidney-only transplants from <18-year-old donors between January 2012 and May 2021 in our center were included in this study. Outcomes were compared between VSPD and normal pediatric donor (NPD, aged 2-18 y) groups, and 3-y death-censored graft survival was assessed by the multivariable Cox proportional hazard model.

RESULTS

Of all 252 enrolled patients, 149 (59.1%) received kidneys from NPDs and 103 (40.9%) from VSPDs. The 3-y graft survival rates of the NPD and VSPD groups were 91.2% and 88.6%, respectively ( P = 0.385). The adjusted hazard ratio of 3-y graft loss was 1.2 (95% confidence interval, 0.6-2.5; P = 0.659) for the VSPD group compared with the NPD group. There was no significant difference in estimated glomerular filtration rate at 3 y posttransplant observed between NPD and VSPD groups (86.9 ± 26.8 versus 87 ± 27.9 mL/min/1.73 m 2 ; P = 0.991). Patients (n = 12, 4.8%) who received kidneys from donors <5 kg contributed 5 (5/39, 12.8%) with delayed graft function and the sole primary nonfunction in our cohort.

CONCLUSIONS

Although attention to preventing complications is necessary, especially for kidneys from donors <5 kg, kidneys from VSPDs did not appear to impart added risk for 3-y graft loss and renal function.

Complex Bench Surgery Does Not Increase the Risk of Vascular Complications after Pediatric Kidney Transplantation

INTRODUCTION

 Vascular complications are severe complications of pediatric kidney transplantation (KT). We aimed to investigate whether a complex bench surgery (BS) affects the outcomes.

METHODS

 All pediatric KT performed at the University Hospital of Padua from 2015 to 2019 were analyzed, comparing those in which a standard BS was possible to those that necessitated a complex BS. The rates of vascular complications, patients' outcome, and graft survival were compared in the two groups.

RESULTS

 Eighty KTs were performed in 78 patients with a median age of 11 years (interquartile range [IQR] 4.3-14) and a median body weight of 24 kg (IQR 13-37). Thirty-nine donor kidneys (49%) needed a complex BS due to anomalies of renal veins in 12 (31%) and renal arteries in 16 (41%). The remaining 11 grafts (28%) underwent an elongation of the vein. There was no difference in the rate of primary graft non function (p = 0.97), delayed graft function (p = 0.72), and overall survival (p = 0.27). The rates of vascular complications, bleedings, and venous graft thrombosis were similar (p = 0.51, p = 0.59, p = 0.78, respectively). No arterial thrombosis or stenosis was reported.

CONCLUSION

 Complex BS did not compromise survival of the graft and did not put the allograft at risk of vascular complications, such as bleedings or thrombosis.

Approach to acute kidney injury following paediatric kidney transplant

PURPOSE OF REVIEW

In a child with evidence of acute kidney injury (AKI) following renal transplantation, it is important to quickly and accurately diagnose the cause to enable timely initiation of therapeutic interventions. The following article will discuss the differential diagnosis of acute graft dysfunction in paediatric kidney transplant recipients. This review will systematically guide the clinician through the common and less common causes and provide updates on current treatments.

RECENT FINDINGS

In patients with signs of graft dysfunction, rejection is an important cause to consider. Diagnosis of rejection relies on biopsy findings, an invasive and costly technique. Over the past 5 years, there has been a focus on noninvasive methods of diagnosing rejection, including serum and urinary biomarkers.

SUMMARY

This review discusses the differential diagnosis of acute graft dysfunction following transplant, with a focus on acute rejection, urinary tract infections and common viral causes, prerenal and postrenal causes, nephrotoxic medications, specifically calcineurin inhibitor toxicity, thrombotic microangiopathy and recurrence of the underlying disease. Each condition is discussed in detail, with a focus on clinical clues to the cause, incidence in the paediatric population, workup and treatment.

Renal transplantation in pediatric recipients: Considerations and preoperative assessment strategies

INTRODUCTION AND OBJECTIVE

Renal transplantation in the pediatric population differs from adults in many aspects. This review will focus on the unique issues of the pediatric recipient.

MATERIAL AND METHODS

A narrative review on the scarce literature regarding preoperative evaluation before kidney transplantation of the paediatric recipient with an educational focus was conducted. The literature search allowed for identification of publications in English from January 2000 to October 2022. Published studies were identified by searching the following electronic databases: PubMed (MEDLINE), WHO/UNAIDS, Google-Scholar, Semantic-Scholar and Research Gate. For efficiency and reliability, recent randomized controlled trials, meta-analyses, high quality systematic reviews and large well-designed studies were used if available. Internet searches were conducted for other relevant information (definitions, policies or guidelines).

RESULTS

Management of congenital urogenital anomalies and lower urinary tract dysfunction along with optimal pediatric urological preoperative assessment for renal transplantation in children is addressed in the light of the available literature. Furthermore, particular considerations including pre-emptive transplantation, transplantation of an adult-size kidney into an infant or small child is discussed.

CONCLUSIONS

Outcomes of RT in children have shown progressive improvement over the past 15 years. Transplantation with living related donor gives the best results and pre-emptive transplantation provides with benefits of avoiding dialysis. Surgical and medical considerations in both the pre-transplant and post-transplant management of the pediatric kidney recipient are extremely crucial in order to achieve better short and long-term results.

Paediatric kidney transplantation: Towards a framework for pretransplant urological evaluation

The role of the urologist in paediatric kidney transplantation has evolved alongside advances in management for the various causes of end-stage kidney disease. Improvements in antenatal intervention and postnatal care have seen children with increasingly complex urological anomalies survive until transplant. Once solely responsible for the oversight of a child's surgical care, the paediatric urologist now works within a multidisciplinary transplant team, alongside transplant surgeons, paediatric nephrologists, transplant coordinators, psychologists, social workers, and transitional care specialists. We sought to identify available pretransplant evaluation frameworks to guide urological preparation and decision-making. Drawing from available evidence and reflecting on multi-institutional experience, we propose a streamlined approach to urologic assessment, which recognises that optimal transplant outcomes in this heterogenous cohort require lower urinary tract dysfunction to be carefully defined preoperatively.

Good outcomes after pediatric intraperitoneal kidney transplant

BACKGROUND

Kidney transplantation in small children is technically challenging. Consideration of whether to use intraperitoneal versus extraperitoneal placement of the graft depends on patient size, clinical history, anatomy, and surgical preference. We report a large single-center experience of intraperitoneal kidney transplantation and their outcomes.

METHODS

We conducted a retrospective review of pediatric patients who underwent kidney transplantation from April 2011 to March 2018 at a single large volume center. We identified those with intraperitoneal placement and assessed their outcomes, including graft and patient survival, rejection episodes, and surgical or non-surgical complications.

RESULTS

Forty-six of 168 pediatric kidney transplants (27%) were placed intraperitoneally in children mean age 5.5 ± 2.3 years (range 1.6-10 years) with median body weight 18.2 ± 5 kg (range 11.4-28.6 kg) during the study period. Two patients (4%) had vascular complications; 10 (22%) had urologic complications requiring intervention; all retained graft function. Thirteen patients (28%) had prolonged post-operative ileus. Eight (17%) patients had rejection episodes ≤6 months post-transplant. Only one case resulted in graft loss and was associated with recurrent focal segmental glomerular sclerosis (FSGS). Two patients (4%) had chronic rejection and subsequent graft loss by 5-year follow-up. At 7-year follow-up, graft survival was 93% and patient survival was 98%.

CONCLUSIONS

The intraperitoneal approach offers access to the great vessels, which allows greater inflow and outflow and more abdominal capacity for an adult donor kidney, which is beneficial in very small patients. Risk of graft failure and surgical complications were not increased when compared to other published data on pediatric kidney transplants.

Encouraging outcomes of using a small-donor single graft in pediatric kidney transplantation

BACKGROUND

The use of small pediatric kidneys as single grafts for transplantation is controversial, due to the potential risk for graft thrombosis and insufficient nephron mass.

METHODS

Aiming to test the benefits of transplanting these kidneys, 375 children who underwent kidney transplantation in a single center were evaluated: 49 (13.1%) received a single graft from a small pediatric donor (≤ 15 kg, SPD group), 244 (65.1%) from a bigger pediatric donor (> 15 kg, BPD group), and 82 (21.9%) from adult living donors (group ALD).

RESULTS

Groups had similar baseline main characteristics. After 5 years of follow-up, children from the SPD group were comparable to children from BPD and ALD in patient survival (94%, 96%, and 98%, respectively, p = 0.423); graft survival (89%, 88%, and 93%, respectively, p = 0.426); the frequency of acute rejection (p = 0.998); the incidence of post-transplant lymphoproliferative disease (p = 0.671); the odds ratio for severely increased proteinuria (p = 0.357); the rates of vascular thrombosis (p = 0.846); and the necessity for post-transplant surgical intervention prior to discharge (p = 0.905). The longitudinal evolution of eGFR was not uniform among groups. The three groups presented a decrease in eGFR, but the slope of the curve was steeper in ALD children. At 5 years, the eGFR of the ALD group was 10 ml/min/1.73m² inferior to the others. At that time, the eGFR from the SPD group was statistically similar to the BPD group (p = 0.952).

CONCLUSION

In a specialized transplant center, the use of a single small pediatric donor kidney for transplantation is as successful as bigger pediatric or adult living donors, after 5 years of follow-up. A higher resolution version of the Graphical abstract is available as Supplementary information.

Can real-time near-infrared spectroscopy monitoring detect graft venous thrombosis after pediatric kidney transplantation?

BACKGROUND

A prompt detection of graft venous thrombosis might preserve the transplanted organ. A real-time near-infrared spectroscopy (NIRS) monitoring of the allograft perfusion could fulfill this goal. The aim of this work was to report the trend of allograft perfusion (rSO2) after pediatric kidney transplantation (KT) complicated by graft venous thrombosis.

CASE PRESENTATION

An infant, affected by end-stage kidney disease due to posterior urethral valves, underwent non-living donor KT. The allograft presented both arterial and venous variants and required a complex bench surgery reconstruction. The perfusion of the allograft was monitored by real-time transcutaneous NIRS. The early post-operative was conditioned by worsening clinical conditions, and a graft venous thrombosis was detected after four hours since the transplantation. NIRS monitoring lasted for 348 minutes. Median lower pole rSO2-value was 65% (IQR 62-66%), while the median upper pole rSO2-value was 70% (IQR 70-71%). These data reflected the congestion of the lower pole, observed at the end of the transplantation. The lower pole showed inferior rSO2 values (p<0.0001). At the end of the monitoring, the decrease in peripheral rSO2, measured in left lower limb as a benchmark, was consistent with the ongoing hypovolemic shock and severe acute anemia.

CONCLUSION

Transcutaneous NIRS might be a reliable device for monitoring allograft and peripheric perfusion after pediatric KT. The modifications of rSO2 values helped the clinicians manage the patients in the post-operative and early detect acute complications.

Thromboprophylaxis after kidney transplantation in children: Ten-year experience of a single Brazilian center

BACKGROUND

Kidney transplantation is the gold standard treatment for children with end-stage chronic kidney disease. Graft thrombosis is an important cause of graft failure, with high morbidity, mortality, and impact on quality of life and to the health system. The role of thromboprophylaxis in this setting is still uncertain. We describe the demographic characteristics and thrombotic risk factors in pediatric renal transplant recipients, determining the rate of renal graft thrombosis, and discuss the role of thromboprophylaxis.

METHODS

This retrospective study reviewed 96 pediatric renal transplantations between 2008 and 2017 in a single hospital. Patients were assigned to one of two groups: children who did not receive thromboprophylaxis after transplantation and those who did. We reported their characteristics, comparing the incidence of graft thrombosis and hemorrhagic complications between the groups.

RESULTS

Forty-nine patients (51%) received thromboprophylaxis. Thrombosis occurred in 5 patients who did not receive thromboprophylaxis (5.2%) compared with none in the group that did (p = .025). In all patients, renal graft thrombosis resulted in early graft loss. Thirteen patients had hemorrhagic complications. Seven were unrelated to pharmacological thromboprophylaxis (2 major, 1 moderate, and 4 minor bleeding, which either did not receive thromboprophylaxis or had bleeding prior to thromboprophylaxis), while six occurred during heparinization (2 major, 1 moderate, and 3 minor bleeding). There was no significant difference in the rate of hemorrhagic complications between the groups (p = .105).

CONCLUSIONS

The rate of renal graft thrombosis was 5.2%. Thrombosis remains an important cause of early graft loss. Thromboprophylaxis was associated with a reduction in graft thrombosis without increased risk of bleeding.

Bench thrombolysis and "autotransplantation" as a rescue treatment for venous thrombosis after living-donor kidney transplantation

BACKGROUND

Allograft venous thrombosis is a severe complication after kidney transplantation (KT). Early diagnosis and prompt treatment are crucial in preserving the survival of the allograft. In this study, we aimed to describe an emergent strategy for the management of acute allograft venous thrombosis.

CASE PRESENTATION

A 4-year-old girl, weighing 13.5 kg, was diagnosed with bilateral congenital renal hypodysplasia, urogenital sinus and anorectal malformation. The patient was referred to our department for living-donor KT. Her mother was eligible as a donor, presenting a body weight ratio of 1:4.5. Thrombosis of the inferior vena cava (ICV) was also identified, without any predisposing factor for thrombophilia. KT was performed by an extraperitoneal approach without complications. Venous anastomosis required a human vascular graft sutured to the ICV, and renal artery was anastomosed to the aorta. On postoperative day (POD) 8, acute abdominal pain and hematuria led to the diagnosis of an allograft venous thrombosis. An emergent laparotomy was required to explant the allograft, followed by bench surgery. The allograft was irrigated with thrombolytic agents and lactated Ringer's solution and then after removing the venous vascular graft, it was reimplanted through vascular anastomosis with the ICV and aorta. The recovery of perfusion and function was good with diuresis since day 4 after re-surgery. At 2-year follow-up, the child presented normal allograft function with an estimated GFR of 65 ml/min/1.73 m² .

CONCLUSION

According to our experience, explantation of the kidney allograft, followed by irrigation with thrombolytics in bench surgery, and reimplantation resulted in unexpected optimal outcomes in the case of allograft venous thrombosis.

Outcomes of small pediatric donor kidney transplants according to donor weight

A small pediatric deceased donor (SPD) weight cutoff whether to transplant as en bloc (EB) or single pediatric (SP) kidney is uncertain. Using UNOS/OPTN data (2000-2019), 27 875 SPDs were divided by (i) EB (11.4%) or SP (88.6%) and (ii) donor weight [≤10 (5.4%), >10-15 (8.3%), >15-18 (3.7%), >18-20 (2.9%), and >20 kg (79.7%)]. SP >20 kg and adult deceased donors (grouped by Kidney Donor Profile Index, KDPI, <30, 30-85, and >85) were used as references. The primary outcome was 10-year graft failure. In SP <10 kg, the hazard ratio (HR) for overall graft failure was 1.64 (1.38-2.20) compared with EB <10 kg, and 1.45 (1.18-1.80) compared with SP >20 kg. In SP >10-15 kg, HR was 1.31 (1.12-1.54) compared with EB >10-15 kg, and 1.04 (0.91-1.18) compared with SP >20 kg. In SP >15 kg, the risk was the same as SP >20 kg. Ten-year overall graft survival of SP 12 kg was comparable to SP >20 kg (62% vs. 57%). Ten-year death censored graft failure of SP >10-15 kg (70%) and SP >15-18 kg (70%) was like the adult donors with KDPI 30-85 (67%). In conclusion, we recommend single kidney transplants from SPDs with weight >12 kg to adult recipients in centers with experience in SPD transplants to optimize organ utilization.

Extraperitoneal kidney transplantation: a comparison between children weighting ≤15 kg and >15 kg. Experience of a single institution

Extraperitoneal approach is sometimes recommended for kidney transplantation (KT) in children weighting <15 kg. We hypothesized that this approach might be as successful as in patients with normal weight. Data of all consecutive KTs performed between 2013 and 2019 were retrospectively reviewed. Early outcomes and surgical complications were compared between children weighing ≤15 kg (low‐weight (LW) group) and those weighing >15 kg (Normal‐weight (NW) group). All the 108 KTs were performed through an extraperitoneal approach. The LW group included 31 patients (mean age 3.5 ± 1.4 years), whose mean weight was 11.1 ± 2.0 kg. In the LW group,—a primary graft nonfunction (PNGF) occurred in one patient (3.2%), surgical complications occurred in nine (29%), with four venous thrombosis. In the NW group, PNGF occurred in one case (1.3%), delayed graft function (DGF) in eight (10%), surgical complications in 11 (14%) with only one case of venous thrombosis. In both groups, no need for patch during wound closure and no wound dehiscence were reported. The extraperitoneal approach can be effectively used in LW children. No differences were observed in the overall complication rate (P = 0.10), except for the occurrence of venous thrombosis (P = 0.02). This might be related to patients’ characteristics of the LW group.

Transcutaneous near-infrared spectroscopy (NIRS) for monitoring kidney and liver allograft perfusion

BACKGROUND

The use of transcutaneous near-infrared spectroscopy (NIRS) for monitoring the perfusion of kidney and liver allografts has been proposed in the last years. This device might detect an early decrease in allograft oxygenation allowing prompt detection of vascular complications.

METHODS

A systematic review of the literature about the use of transcutaneous NIRS in monitoring allograft perfusion was performed according to the PRISMA guidelines.

RESULTS

The authors screened 1313 papers. The search yielded five pertinent articles. Three of them reported the experience of NIRS in kidney transplantation and the other two dealt with its use in liver transplantation, for a total of 55 paediatric patients and 121 adults. In the studies concerning kidney transplantation, NIRS measurements were significantly related to serum creatinine, estimated glomerular filtration rate (eGFR), urinary neutrophil gelatinase-associated lipocalin (u-NGAL), serum lactate, resistive index assessed by Doppler-ultrasonography and systolic blood pressure. The two studies dealing with liver transplantation found a significant decrease in liver regional oxygenation, assessed by NIRS, before the occurrence of vascular complications.

CONCLUSIONS

Preliminary studies have related NIRS monitoring to kidney and liver allograft perfusion, both in adults and children. Further investigation is needed to establish the normal range of NIRS values and the factors influencing NIRS monitoring.

Transplantation of a single kidney from pediatric donors less than 10 kg to children with poor access to transplantation: a two-year outcome analysis

Background

Access to kidney transplantation by uremic children is very limited due to the lack of donors in many countries. We sought to explore small pediatric kidney donors as a strategy to provide transplant opportunities for uremic children.

Methods

A total of 56 cases of single pediatric kidney transplantation and 26 cases of en bloc kidney transplantation from pediatric donors with body weight (BW) less than 10 kg were performed in two transplant centers in China and the transplant outcomes were retrospectively analyzed.

Results

The 1-year and 2-year death-censored graft survival in the en bloc kidney transplantation (KTx) group was inferior to that in the single KTx group. Subgroup analysis of the single KTx group found that the 1-year and 2-year death-censored graft survival in the group where the donor BW was between 5 and 10 kg was 97.7 and 90.0%, respectively. However, graft survival was significantly decreased when donor BW was ≤5 kg (p < 0.01), mainly because of the higher rate of thrombosis (p = 0.035). In the single KTx group, the graft length was increased from 6.7 cm at day 7 to 10.5 cm at 36 months posttransplant. The estimated glomerular filtration rate increased up to 24 months posttransplant. Delayed graft function and urethral complications were more common in the group with BW was ≤5 kg.

Conclusions

Our study suggests that single kidney transplantation from donors weighing over 5 kg to pediatric recipients is a feasible option for children with poor access to transplantation.