Renal perfusion in infant recipients of adult-sized kidneys is a critical risk factor

Comparison of live donor predonation and post-transplant kidney volumes and glomerular size in pediatric patients weighing less than 15 kg - a retrospective study

Renal transplantation of adult-size kidneys presents a size mismatch in small children. This study presents a comparison of live donor predonation and recipient post-transplant kidney volumes (k-vol) and glomerular size at 1 year after transplantation. We analyzed 47 pediatric renal transplant recipients weighing <15 kg between 2009 and 2017. The k-vol before and 1 year after transplantation and glomerular size at implant and 1 year post-transplant were evaluated. We estimated the relationships between these changes and graft function, and the factors associated with k-vol. Pretransplant k-vol was 158.1 ± 25.1 ml, and the k-vol at 1 year post-transplant was significantly reduced by -17.2% to 132.3 ± 27.3 ml (P < 0.001). Implant glomerular size showed the diameter was 165.3 ± 15.1 µm and the area 20 737.1 ± 3230.6 µm² . One-year post-transplant, the glomerular diameter was 150.6 ± 11.4 µm and the area 17 428.3 ± 2577.9 µm² , significantly reduced compared with implantation values (both P < 0.001). The change in k-vol was affected by pretransplant abdominal cavity (ml/200 ml cavity volume, partial regression coefficient = 0.029, SE = 0.009, P = 0.004) and recipient's weight gain (ml/5% of weight gain, partial regression coefficient = 0.020, SE = 0.006, P = 0.002). In small pediatric transplants, an adult-size kidney is acceptable with reduction in k-vol. Moreover, the post-transplant k-vol might be regulated by pretransplant physique and post-transplant somatic growth.

Perioperative renal transplantation management in small children using adult-sized living or deceased donor kidneys: A single-center experience

Kidney transplantation remains the treatment of choice for children with ESRD. Optimal perioperative management is critical in small recipients of ASK to assure adequate graft perfusion. We present a single-center experience outlining management for patients weighing <20 kg who underwent primary renal transplantation with ASKs between 2007 and 2016. Sixty-three patients met study criteria and underwent 34 living-related, six living-unrelated, and 23 deceased donor kidney transplants. Median age and weight at transplant were 25 months (IQR 18-37 months; range 11 months-6 years) and 11.0 kg (IQR 9.2-14.5 kg; range 7.1-19.5 kg). Eighty-nine percent of patients required vasoactive agents intra-operatively, with twenty patients requiring prolonged vasoactive agents post-operatively. Intra-operatively, patients received 51.9 mL/kg of crystalloid, 27.3 mL/kg of 5% albumin, and 13.6 mL/kg of packed red blood cells. Most (93.7%) patients were extubated on POD#0. Weights peaked on post-operative days three through five. Over a median follow-up of 49 months (IQR 31-86 months; range 0-130 months), four grafts were lost, two due to thrombosis and two secondary to chronic rejection. There was one patient death six months post-transplant due to causes unrelated to transplantation. Graft survival at 1, 5, and 10 years was 98.4%, 96.6%, and 84.2%, respectively. Of surviving allografts, the median 1, 5, and 10 years post-transplant eGFR was 122.9, 90.0, and 59.2 mL/min/1.73 m² as determined by the 2009 Schwartz formula. Renal transplantation in small children using ASKs requires meticulous perioperative management including adequate fluid resuscitation and judicious use of pressors to assure adequate graft perfusion. The use of ASKs from living or deceased donors results in satisfactory short and long-term outcomes.

Is there a functional disadvantage to using the external iliac vessels for vascular anastomosis in children and adolescents undergoing renal transplantation?

PURPOSE

RT remains the best available strategy for addressing stage 5 chronic kidney disease in children and adolescents. Technical aspects of the procedure can have a clear impact on complications and health of the allograft, including DGF. Immediate optimal perfusion is paramount, thus choosing a target vessel has to take into account the flow demands imposed by an adult-size kidney in a proportionally smaller recipient. Herein, we explore the hypothesis that vascular anastomosis location can impact DGF adjusting for patient age and body size.

METHODS

Retrospective review of a single institution referral center transplant database, including information on 156 patients. We collected data on patient characteristics (age, height, BSA, gender, preoperative need for dialysis), donor source (deceased vs living), WIT/CIT, hemodynamics during the procedure, use of inotropes or diuretics, and location of the arterial and venous anastomoses. The primary outcome, DGF, was assessed by measuring the ttNC (in days), adjusting for age and BSA.

RESULTS

Location of the arterial anastomosis was clearly impacted by age and donor size (Figure 1A). On univariate analyses, longer ttNC was associated with deceased vs living donor (11.8 ± 11.5 and 4.3 ± 5.0; P < 0.001), preoperative need for dialysis (9.7 ± 11.0 and 6.5 ± 6.0, P = 0.02), location of arterial anastomosis (aorta [n = 21] 4.9 ± 6.1, common iliac [n = 93] 7.1 ± 7.3, external iliac 14.7 ± 14.5; P < 0.001, Figure 1B) and venous anastomosis (vena cava [n = 21] 5.6 ± 6.3, common iliac [n = 89] 7.1 ± 7.6, external iliac [n = 44] 13.8 ± 14); P < 0.001). On multivariable analysis, this association remained statistically significant when adjusting for recipient age, height, BSA, donor source, change in blood pressure with unclamping, and use of inotropes and preoperative dialysis. The detrimental effect on ttNC was more salient when comparing external iliac vs common iliac and aorta or vena cava.

CONCLUSION

Our data suggest that anastomosis to a smaller caliber target vessel (ie, external iliac) in comparison with the common iliac or aorta/vena cava may be a risk factor for delayed return of graft function, independent of recipient size and donor source. This finding merit further evaluation, as it may help with intraoperative decision making during pediatric and adolescent RT.

What has changed in pediatric kidney transplantation in Turkey? Experience of an evolving center

INTRODUCTION

Reluctance to perform kidney transplantations on children is an ongoing problem in Turkey. Moreover, urological pathologies still constitute the largest portion of the underlying etiologies in chronic renal failure patients. Herein, we retrospective analyzed the data acquired from our pediatric renal transplantation patients and reviewed the registry of dialysis and transplantation data prepared by the Turkish Society of Nephrology.

MATERIAL AND METHODS

Forty-six living donor kidney transplantations were performed in children between 2008 and 2012. Seventeen of 46 (37%) transplantations were preemptive. The mean age at operation time was 10.8 ± 5 years. The mean patient weight was 31.3 ± 15.8 kg (range, 9.4 to 66.4 kg). A detailed urologic evaluation was performed for every child with an underlying lower urinary tract disease. One enterocystoplasty and 2 ureterocystoplasties were performed for augmentation of the bladder, simultaneously.

RESULTS

One-year death-censored graft survival and patient survival rates were 100% and 97.8%, respectively. The mean serum creatinine level was 0.86 ± 0.32 mg/dL (range, 0.3 to 1.8 mg/dL). None of the patients had vascular complications or acute tubular necrosis. One patient suffered graft-versus-host disease during the second month after renal transplantation and died with a functioning graft. In one patient with massive proteinuria detected after transplantation, recurrence of primary disease (focal segmental glomerulosclerosis) was considered and the patient was treated successfully with plasmapheresis. One child had an acute cellular rejection and was administered pulse steroid treatment.

CONCLUSION

Although challenging, all patients in all pediatric age groups can successfully be operated and managed. With careful surgical technique, close postoperative follow-up, and efforts by the experienced and respectful surgical teams in this country, we could change the negative trends toward perform kidney transplantation in the Turkish pediatric population.

Subclinical inflammation and chronic renal allograft injury in a randomized trial on steroid avoidance in pediatric kidney transplantation

Steroid avoidance is safe and effective in children receiving kidney transplants in terms of graft function and survival, but the effects on allograft histology are unknown. In this multicenter trial, 130 pediatric renal transplant recipients were randomized to steroid-free (SF; n = 60) or steroid-based (SB; n = 70) immunosuppression, and underwent renal allograft biopsies at the time of graft dysfunction and per protocol at implantation and 6, 12 and 24 months after transplantation. Clinical follow-up was 3 years posttransplant. Subclinical acute rejection was present in 10.6% SF versus 11.3% SB biopsies at 6 months (p = 0.91), 0% SF versus 4.3% SB biopsies at 1 year (p = 0.21) and 0% versus 4.8% at 2 years (p = 0.20). Clinical acute rejection was present in 13.3% SF and 11.4% SB patients by 1 year (p = 0.74) and in 16.7% SF and 17.1% SB patients by 3 years (p = 0.94) after transplantation. The cumulative incidence of antibody-mediated rejection was 6.7% in SF and 2.9% in SB by 3 years after transplantation (p = 0.30). There was a significant increase in chronic histological damage over time (p < 0.001), without difference between SF and SB patients. Smaller recipient size and higher donor age were the main risk factors for chronic histological injury in posttransplant biopsies.

Transplantation of adult-sized kidneys in low-weight pediatric recipients achieves short-term outcomes comparable to size-matched grafts

Low-weight pediatric recipients are disadvantaged by scarcity of size-matched donors. ASK have been successfully used for pediatric recipients. We report the results of renal transplantation using ASK in low-weight pediatric recipients and compare outcomes in weight-matched and unmatched donor-recipient pairs. The outcomes of renal transplants using ASK grafts in low-weight (<20 kg) recipients from a single center over a 10-yr period were reviewed. Two groups, comprising recipients of grafts from weight-matched and mismatched donors, were compared. Primary outcome was one-yr graft survival. Secondary outcomes were one- and two-yr calculated eGFR, changes in recipient body weight, perioperative cardiovascular stability, rates of AR and DGF. Twenty-three low-weight recipients were transplanted. Eleven received ASK grafts from high-weight donors and 12 grafts from low-weight donors. One patient in each group had early graft loss. No significant difference was observed in rates of DGF, AR, one-yr graft or patient survival and perioperative cardiovascular parameters. ASK with considerable donor:recipient weight discrepancies can be safely transplanted into small pediatric recipients with comparable outcomes to grafts with less weight discrepancy.

The effect of donor/recipient body surface area ratio on outcomes in pediatric kidney transplantation

In pediatric kidney transplantation, the effect of inadequate nephron dosing on graft survival remains undetermined. The aim of this study was to assess the use of D/R BSA, as a reliable indicator of adequate nephron dosing, and eventually a tool to optimize pediatric graft allocation. Following Institutional Review Board approval, we reviewed deceased donor pediatric kidney transplantation (N = 156). We divided patients into three groups, based on D/R BSA: A < or =0.8; B 0.81-1.19; C > or =1.2. Five-yr graft survival rates in the groups were: A 82.0%; B 94.9%; C 97.1% (p = 0.01). Group C had the lowest rate of acute rejection, suggesting a protective effect of increased D/R BSA (group A = 35.7%, group B = 38.9%, group C = 18.8%; p = 0.029). The logistic regression analysis showed that decreased D/R BSA ratio is a risk factor for loss of graft function, at one and five yr [i.e., group A OR 6 (95% CI 1.14-39.30, p = 0.015) and OR 4.49 (95% CI 1.46-13.79, p = 0.009), respectively]. We conclude that for pediatric recipients, D/R BSA is a valuable adjunct when determining long-term graft survival. Its utility may avoid an alloimmune-independent risk factor, increasing the long-term protective value of a good matching policy.

Congenital nephrotic syndrome

Congenital nephrotic syndrome (CNS) is a rare kidney disorder characterized by heavy proteinuria, hypoproteinemia, and edema starting soon after birth. The majority of cases are caused by genetic defects in the components of the glomerular filtration barrier, especially nephrin and podocin. CNS may also be a part of a more generalized syndrome or caused by a perinatal infection. Immunosuppressive medication is not helpful in the genetic forms of CNS, and kidney transplantation is the only curative therapy. Before the operation, management of these infants largely depends on the magnitude of proteinuria. In severe cases, daily albumin infusions are required to prevent life-threatening edema. The therapy also includes hypercaloric diet, thyroxin and mineral substitution, prevention of thrombotic episodes, and prompt management of infectious complications. The outcome of CNS patients without major extrarenal manifestations is comparable with other patient groups after kidney transplantation.

The evolution of nonimmune histological injury and its clinical relevance in adult-sized kidney grafts in pediatric recipients

To describe the evolution, risk factors and impact of nonimmune histological injury after pediatric kidney transplantation, we analyzed 245 renal allograft protocol biopsies taken regularly from the time of transplantation to 2 years thereafter in 81 consecutive rejection-free pediatric recipients of an adult-sized kidney. Isometric tubular vacuolization was present early after transplantation was not progressive, and was associated with higher tacrolimus pre-dose trough levels. Chronic tubulo-interstitial damage and tubular microcalcifications were already noted at 3 months, were progressive and had a greater association with small recipient size, male donor gender, higher donor age and female recipient gender, but not with tacrolimus exposure. Renal function assessment showed that older recipients had a significant increase in absolute glomerular filtration rate with time after transplantation, which differed from small recipients who showed no increase. It is concluded that progressive, functionally relevant, nonimmune injury is detected early after adult-sized kidney transplantation in pediatric recipients. Renal graft ischemia associated with the donor-recipient size discrepancy appears to be a greater risk factor for this chronic histological injury, suggesting that the exploration of additional therapeutic approaches to increase allograft perfusion could further extend the graft survival benefit of adult-sized kidneys transplanted into small children.

Renal transplantation in children younger than 6 years old

Herein we report our experience in renal transplantation in 38 children (40 transplants), ages 1 to 5 years, between 1989 and 2005. Demographics as well as patient and graft survivals are reported. Mean age at transplantation was 3.3 +/- 1.3 years, and mean weight was 14 kg (range, 5.7-25 kg); 92.5% were Caucasian, 7.5% African-Brazilian. The main etiology for end-stage renal disease (ESRD) was uropathic/vesicoureteral reflux (45%) followed by glomerulopathy (25%), congenital/hereditary diseases (10%), and hemolytic uremic syndrome (12.5%). Prior to transplantation, 5% were on hemodialysis, 85% on peritoneal dialysis, and 10% preemptive. All children were followed for at least 6 months posttransplantation, except 2 who died in the first month. In 75% of cases, kidneys were obtained from living-related donors, and in 25% from deceased donors. Thirty-nine kidneys were extraperitoneally placed. Primary immunosuppressant therapy consisted of cyclosporine (61%), tacrolimus (39%), mycophenolate (49%), and azathioprine (51%). A steroid-free protocol was used in 17% of patients. In the last 21 cases, basiliximab or daclizumab was added. There were 13 (32.5%) graft losses (4 artery/vein thromboses, 3 chronic rejections, 3 deaths, 3 other causes). The 5-year patient and graft survival rates were 89.6% and 72.2%. We have concluded that renal transplantation can be performed with good long-term results in children younger than 6 years old.

Pediatric renal transplantation with considerations for successful outcomes

Renal transplantation in the pediatric population, although conceptually similar to that in adults, differs in many aspects. This review will focus on the issues unique to the pediatric recipient. In particular, we will focus on the incidence and etiology of end stage renal disease in children, and the results as measured by patient and graft survival. Pretransplant surgical considerations of timing of the transplant, management of congenital urologic abnormalities and the abnormal bladder will be addressed. Etiologies of renal failure unique to the pediatric population will be discussed, including autosomal recessive polycystic kidney disease, congenital nephrotic syndrome, inferior vena cava thrombosis, and primary hyperoxaluria Type 1. Lastly, special transplant surgical considerations including transplantation of an adult-size kidney (ASK) into an infant or small child and ureteral implantation, management of the urinary bladder, and fluid management in infants and small children will be discussed.

Porcine dermal collagen graft in pediatric renal transplantation

Successful closure of the anterior abdominal wall in infants following renal transplantation of adult organs may present a challenging dilemma to the transplant surgeon. Restricted volume of the recipient abdominal cavity and size discrepancy of donor adult kidney may lead to graft compromise. Pressure on the graft may be exacerbated further in the postoperative period by oedema that may lead to abdominal compartment syndrome. Donor/recipient size disparity remains the major obstacle in infant renal transplantation. We describe the use of a porcine collagen graft to facilitate closure of the abdominal wall following intra-peritoneal transplantation of an adult cadaveric kidney.

Risk Factors for Short- and Long-term Survival of Primary Cadaveric Renal Allografts in Pediatric Recipients: A UNOS Analysis

BACKGROUND

Pediatric kidney graft survival rates have improved in the United States. This study evaluates early and late risk factors for cadaveric graft loss in pediatric recipients.

METHODS

From January 1994 to December 2002, 2,597 primary cadaveric kidney-alone transplants (donor age 5-45 years, recipient age 2-20 years) were reported to the United Network for Organ Sharing (UNOS). The analysis includes follow-up information based on OPTN data as of October 14, 2003. Odds ratio of early graft loss and relative risk of late graft loss are estimated using logistic regression and Cox proportional hazards model, respectively.

RESULTS

Graft survival rates significantly improved during 1999-2002 (95% and 79% at 1-year and 3-years, respectively) compared with those of 1994-1998 (88% and 76% at 1-year and 3-years, respectively) (log rank P=0.02). After adjusting for other variables, the factors that significantly affected early transplant outcome adversely within 3 months posttransplant were prolonged cold ischemia time (>36 hours, odds ratio [OR]=3.38 vs. 0-36 hours) and young recipient age (2-5 years old, OR=2.02 vs. 6-12 years). Beyond 3 months, significant risk factors were African-American recipients (relative risk [RR]=1.93 vs. others), teenage recipients (13-20 yrs, RR=1.50 vs. 6-12 yrs), and patients with focal glomerulosclerosis (FGS) (RR=1.27 vs. others).

CONCLUSIONS

The short-term graft survival rate of pediatric cadaveric kidney transplants has significantly improved, yet the long-term outcome has changed little. The long-term outcomes for teenagers (13-20 yrs), patients with FGS, and African-Americans lag significantly behind other groups. In order to improve long-term graft survival in these high-risk patients, newer preventive or treatment strategies must be developed.