Practice recommendations for the monitoring of renal function in pediatric non-renal organ transplant recipients

Effect of perioperative management on early graft function in living donor paediatric kidney transplantation

BACKGROUND

Paediatric kidney transplantation has an increased risk of surgical and vascular complications, with intensive care monitoring required postoperatively. This study aimed to determine if perioperative management affects early graft function in living donor paediatric kidney transplantation.

METHODS

Clinical data was extracted from the electronic medical record for living donor kidney transplants at two paediatric centres covering the state of New South Wales (NSW), Australia from 2009 to 2021. Estimated glomerular filtration rate (eGFR) of 7 days and 1-month post-transplant were calculated as measures of early graft function.

RESULTS

Thirty-nine eligible patients (female n (%) 13 (33%)) with a median (IQR) age of 6 (3-9) years and pre-transplant eGFR of 7 (6-10) mL/min/1.73 m2 were analysed. Mean (SD) central venous pressure (CVP) after revascularisation was 11 (4) mmHg. Intraoperatively, mean volume of fluid administered was 84 (39) mL/kg, and 34 (87%) patients received vasoactive agents. Average systolic blood pressure (BP) in the first 24-h post-transplant was 117 (12) mmHg. Postoperatively, median volume of fluid administered in the first 24 h was 224 (159-313) mL/kg, and 17 (44%) patients received vasoactive agents. Median eGFR 7 days and 1-month post-transplant were 115 (79-148) and 103 (83-115) mL/min/1.73 m2, respectively. Linear regression analyses demonstrated that after adjusting for age, the average CVP after revascularisation and average systolic BP in the first 24-h post-transplant were not associated with eGFR in the first month post-transplant.

CONCLUSIONS

Targeted intraoperative and postoperative fluid and haemodynamic characteristics were achieved but did not correlate with early graft function.

Acute Hospital Outcomes for Renal Transplantation in Patients With Moderate or Severe Congenital Heart Disease

Children and adults with congenital heart disease (CHD) are increasingly recognized to be at risk for acute and chronic renal injury. Some of these may progress to the need for renal transplantation. We hypothesized that patients with underlying moderate or severe CHD who undergo renal transplantation will have worse acute hospital outcomes. Using a national administrative database, we queried for admissions aged 0 to 50 years with moderate or severe CHD and renal transplantation and compared these to admissions without CHD. There were 56 admissions for renal transplantation in the CHD group (0.04%) and 26,285 admissions in the group without CHD (0.21%, p<0.001). The CHD group were younger, had a higher proportion of Whites, longer length of stay, higher complication rates, higher in-hospital mortality, and higher costs. In conclusion, although renal transplantation is still relatively uncommon in the CHD population, there is an increasing recognition of severe chronic renal disease in the setting of CHD, making it important to understand the potential implications of these findings.

Kidney disease in children with heart or liver transplant

Over the past few decades, there has been increasing recognition of kidney disease in children with non-kidney solid organ transplantation. The risk of kidney disease in children undergoing heart or liver transplantation is higher than the general population as the underlying disease and its associated management may directly impair kidney function. Both heart and liver failures contribute to hypoperfusion and kidney ischemia before patients reach the point of transplant. The transplant surgery itself can often be complicated by acute kidney injury (AKI), which may be further exacerbated by a complicated postoperative course. In the short- and long-term post-transplant period, these children are at risk of acute illness, exposed to nephrotoxic medications, and susceptible to rare but severe infections and immunologic insults that may contribute to AKI and chronic kidney disease (CKD). In some, CKD can progress to kidney failure with replacement therapy (KFRT). CKD and KFRT are associated with increased morbidity and mortality in this patient population. Therefore, it is critical to monitor for and recognize the risk factors for kidney injury in this population and mitigate these risks. In this paper, the authors provide an overview of kidney disease pertaining to heart and liver transplantation in children with guidance on monitoring, diagnosis, prevention, and management.

Long-Term Follow-Up of Renal Function in Children after Liver Transplantation-A Single Center Retrospective Study

Chronic kidney disease (CKD) is a common complication after liver transplantation (LT). Its prevalence with modern immunosuppression regimens, especially in children, is variable depending on the transplantation era. The study included 61 pediatric patients with at least 10 years of follow-up after liver transplantation remaining under constant care of the Department of Pediatric Surgery and Organ Transplantation. The analysis included several tests: estimated glomerular function (eGFR), results of screening for renal tubular defects and blood concentrations of basic immunosuppressive drug-tacrolimus. CKD was diagnosed in 3% of children at 12 years after LT. The maintaining of tacrolimus concentrations >4 ng/mL in long-term observation was associated with a significant increase of microalbuminuria. The presence of microalbuminuria, regarded as a risk factor of CKD, confirmed the necessity of regular comprehensive assessment of patients in long-term follow-up.

Adherence to laboratory testing in pediatric liver transplant recipients

BACKGROUND

The objectives of this retrospective cohort study are to describe rates of adherence to laboratory testing 6 months to 3 years post-liver transplantation and to examine demographic and clinical factors related to lab non-adherence and the association with medication adherence and clinical outcomes.

METHODS

Medical chart review was conducted for 54 youth (mean age = 5.0 years) transplanted between 2003 and 2014. Lab adherence (≥80%) was measured as the proportion of completed labs out of the number expected. Immunosuppressant drug-level variability was used as a proxy for medication adherence. Clinical outcomes included LAR, viral infection, hospitalization, and non-routine clinic visit ≥12 months after transplant.

RESULTS

Lab adherence decreased substantially over time. Single-parent household (aOR 5.86; 95% CI: 1.38-24.93) and no history of early rejection (aOR 3.96; 95% CI: 1.04-15.24) were independently associated with non-adherence. Lab non-adherence was significantly associated with medication non-adherence (P < .05), LAR (P = .02), and non-routine clinic visits (P = .03).

CONCLUSIONS

Systematic monitoring of lab adherence may help in identifying pediatric LT recipients at increased risk for excessive healthcare use and adverse outcomes possibly due to poor disease management.

Acute kidney injury and chronic kidney disease after non-kidney solid organ transplantation

BACKGROUND

SOT is the treatment of choice for end-stage organ disease. Improved long-term survival after NKSOT has uncovered chronic morbidity including CKD. AKI is common after NKSOT and may be associated with long-term CKD.

METHODS

We performed a retrospective cohort study looking at AKI and CKD after pediatric heart (n = 109) or liver (n = 112) transplant. AKI was defined using KDIGO creatinine-based criteria. pAKI was AKI ≤ 7 days post-transplant; CKD_3-5 was eGFR < 60 mL/min/1.73 m² by modified Schwartz formula for > 3 months. We looked at the incidence of CKD_3-5 and the effect of perioperative pAKI on the slope of eGFR post-transplant.

RESULTS

pAKI was seen in 63% (n = 69) after heart and 38% (n = 43) after liver transplant. pAKI was associated with longer ICU and hospital stays. Cumulative incidence (95% CI) of CKD_3-5 at 60 months post-heart transplant was 40.9% (27.9%-57.1%) in patients with AKI vs 35.8% (17.1%-64.8%) in those without (P = NS). Post-liver transplant, the cumulative incidence of CKD_3-5 at 60 months was 0% in those without pAKI vs 10% (3.2%-29.3%) in those with (P = .01). Patients with pAKI had lower eGFR at last follow-up.

CONCLUSION

pAKI and CKD are common after NKSOT. Incidence of CKD is higher in those with pAKI. AKI episodes are associated with a drop in eGFR during follow-up. Identifying patients who have had AKI is an important first step in identifying those at risk of repeated AKI episodes. These patients would benefit from closer monitoring for CKD, lower nephrotoxic drug use, and follow-up with nephrology.

High Burden of Subclinical Cardiovascular Target Organ Damage After Pediatric Liver Transplantation

Cardiovascular (CV) events account for 8%-13% of deaths after liver transplantation (LT) in adulthood. Although CV risk factors (RFs) are present, little is known about the prevalence of subclinical CV target organ damage (TOD) in children after LT. The aim of this prospective observational study was to assess the prevalence of subclinical CV TOD in children after LT and to identify RFs contributing to CV damage as potential targets for clinical intervention. In this study, 104 children after LT (54% female, 46% male; aged 11.5 ± 3.8 years) underwent cross-sectional assessment of subclinical TOD by carotid-femoral pulse wave velocity (PWV), carotid intima-media thickness (IMT), and left ventricular mass index (LVMI). Results were correlated with the presence of CV RFs (obesity, hypertension, dyslipidemia, renal impairment, anemia, and microinflammation). Of the patients, 22% were exposed to 2 CV RFs, and 36% displayed 3 or more CV RFs. Pathological results for PWV, IMT, and LVMI were found in 21.9%, 57.0%, and 11.1% of patients, respectively. In the multivariate analysis, diastolic blood pressure (P = 0.01) and estimated glomerular filtration rate (eGFR; P = 0.03) were independently associated with PWV, eGFR (P = 0.005), and age at LT (P = 0.048) with IMT and body mass index with LVMI (P = 0.004). In conclusion, patients after pediatric LT carry a substantial burden of subclinical CV TOD. Identification of modifiable CV RFs opens opportunities for targeted intervention in order to reduce CV morbidity and mortality in the future.

Clinical value of ambulatory blood pressure in pediatric patients after renal transplantation

Hypertension is a highly prevalent co-morbidity in pediatric kidney transplant recipients. Undertreated hypertension is associated with cardiovascular complications and negatively impacts renal graft survival. Thus, the accurate measurement of blood pressure is of the utmost importance for the correct diagnosis and subsequent management of post-renal transplant hypertension. Data derived from the general population, and to a lesser extent from the pediatric population, indicates that ambulatory blood pressure monitoring (ABPM) is superior to blood pressure measurements taken in the clinical setting for the evaluation of true mean blood pressure, identification of patients requiring antihypertensive treatment, and in the prediction of cardiovascular outcome. This Educational Review will discuss the clinical value of ABPM in the identification of individual blood pressure phenotypes, i.e., normotension, new-onset hypertension, white-coat hypertension, masked hypertension, controlled blood pressure, and undertreated/uncontrolled hypertension in pediatric kidney transplant recipients. Finally, we examine the utility of performing repeated ABPM for treatment monitoring of post-renal transplant hypertension and on surrogate markers related to relevant clinical cardiovascular outcomes. Taken together, our review highlights the clinical value of the routine use of ABPM as a tool for identifying and monitoring hypertension in pediatric kidney transplant recipients.

Patterns of kidney injury in pediatric nonkidney solid organ transplant recipients

The incidence of acute kidney injury (AKI) and its impact on chronic kidney disease (CKD) following pediatric nonkidney solid organ transplantation is unknown. We aimed to determine the incidence of AKI and CKD and examine their relationship among children who received a heart, lung, liver, or multiorgan transplant at the Hospital for Sick Children between 2002 and 2011. AKI was assessed in the first year posttransplant. Among 303 children, perioperative AKI (within the first week) occurred in 67% of children, and AKI after the first week occurred in 36%, with the highest incidence among lung and multiorgan recipients. Twenty-three children (8%) developed CKD after a median follow-up of 3.4 years. Less than 5 children developed end-stage renal disease, all within 65 days posttransplant. Those with 1 AKI episode by 3 months posttransplant had significantly greater risk for developing CKD after adjusting for age, sex, and estimated glomerular filtration rate at transplant (hazard ratio: 2.77, 95% confidence interval, 1.13-6.80, P trend = .008). AKI is common in the first year posttransplant and associated with significantly greater risk of developing CKD. Close monitoring for kidney disease may allow for earlier implementation of kidney-sparing strategies to decrease risk for progression to CKD.

The importance of cardiovascular disease in pediatric transplantation and its link to the kidneys

Cardiovascular disease is a frequent cause of morbidity and mortality in pediatric patients following solid organ transplant. CKD is also common in pediatric patients after a solid organ transplant, and the link between CKD and cardiovascular morbidity is strong. In this review, we examine potential etiologies to explain the risk of cardiovascular morbidity and mortality in pediatric solid organ recipients and identify targets for improving outcomes.

Combined and sequential liver-kidney transplantation in children

Combined and sequential liver-kidney transplantation (CLKT and SLKT) is a definitive treatment in children with end-stage organ failure. There are two major indications: - terminal insufficiency of both organs, or - need for transplanting new liver as a source of lacking enzyme or specific regulator of the immune system in a patient with renal failure. A third (uncommon) option is secondary end-stage renal failure in liver transplant recipients. These three clinical settings use distinct qualification algorithms. The most common indications include primary hyperoxaluria type 1 (PH1) and autosomal recessive polycystic kidney disease (ARPKD), followed by liver diseases associated with occasional kidney failure. Availability of anti-C5a antibody (eculizumab) has limited the validity of CLKT in genetic atypical hemolytic uremic syndrome (aHUS). The liver coming from the same donor as renal graft (in CLKT) is immunologically protective for the kidney and this provides long-term rejection-free follow-up. No such protection is observed in SLKT, when both organs come from different donors, except uncommon cases of living donation of both organs. Overall long-term outcome in CLKT in terms of graft survival is good and not different from isolated liver or kidney transplantation, however patient survival is inferior due to complexity of this procedure.

Intraoperative hemodynamic factors predicting early postoperative renal function in pediatric kidney transplantation

BACKGROUND

The anesthetic management of kidney transplantation in children remains somewhat empirical. The goal of the present study was to investigate intraoperative hemodynamic factors affecting posttransplantation kidney function.

METHODS

We performed a retrospective analysis of data from patients undergoing kidney transplantation in our pediatric teaching hospital from 2000 to 2014. Data collected included: donor and recipient demographic data, recipient comorbidities, fluids administered intraoperatively, and intraoperative blood pressure and central venous pressure. The main outcome of the study was the creatinine clearance at day 1 corrected to a body surface area of 1.73 m². Analysis was performed using Classification Tree Analysis with 10-fold cross-validation.

RESULTS

One hundred and two patients were included. The following predictors of increased postoperative creatinine clearance at day 1 were identified: decreasing recipient weight, mean blood pressure-to-weight ratio 10 minutes after reperfusion, reduced cold ischemia duration, and increased intraoperative albumin infusion. Increased creatinine clearance was observed when mean blood pressure-to-weight ratio 10 minutes after reperfusion was ≥4.3 in patients weighing 13-21 kg and ≥2.5 in those ≥22 kg. Overall, the model explained 64% (and at cross-validation 60%) of creatinine clearance variability at day 1.

CONCLUSION

Intraoperative hemodynamics during kidney transplantation should be optimized in order to increase mean blood pressure according to values indicated by our analyses. Cold ischemia duration should be shortened as far as possible.