Preserved Cerebral Oxygenation with Worsening Global Myocardial Strain during Pediatric Chronic Hemodialysis

Background Cerebral and myocardial hypoperfusion occur during hemodialysis in adults. Pediatric patients receiving chronic hemodialysis have fewer cardiovascular risk factors, yet cardiovascular morbidity remains prominent. Methods We conducted a prospective observational study of pediatric patients receiving chronic hemodialysis to investigate whether intermittent hemodialysis is associated with adverse end organ effects in the heart or with cerebral oxygenation (regional O2 saturation [rSO2]). We assessed intradialytic cardiovascular function and rSO2, using noninvasive echocardiography to determine myocardial strain and continuous noninvasive nearinfrared spectroscopy for rSO2. We measured changes in blood volume and central venous oxygen saturation (mCVO2) were pre-, mid-, and post-hemodialysis. Results The study included 15 patients (median age, 12 years; median hemodialysis vintage 13.2 [9, 24] months were included. Patients were asymptomatic. The rSO2 did not change during hemodialysis, whereas mCVO2 decreased significantly, from 73% to 64.8 %. Global longitudinal strain of the myocardium worsened significantly by mid-hemodialysis and persisted post-hemodialysis. The ejection fraction remained normal. Lower systolic blood pressure and faster blood volume change were associated with worsening myocardial strain; only blood volume change was significant in multivariate analysis (β coefficient, -0.3; 95% confidence interval [95% CI], −0.38 to −0.21; P=0.0001). Blood volume change was also associated with a significant decrease in mCVO2 (β coefficient 0.42; 95% CI, 0.07 to 0.76; P=0.001). Access, age, hemodialysis vintage, and ultrafiltration volume were not associated with worsening strain. Conclusion s Unchanged rSO2 suggested that cerebral oxygenation was maintained during hemodialysis. However, despite maintained ejection fraction, intradialytic myocardial strain worsened in pediatric hemodialysis and was associated with blood volume change. The effect of hemodialysis on individual organ perfusion in pediatric versus adult patients receiving hemodialysis might differ.

MO768VASCULAR ACCESS FOR PEDIATRIC HEMODIALYSIS PATIENTS IN CATALONIA: ANALYSIS OF DATA FROM THE CATALAN RENAL REGISTRY (1997-2018)

Background The vascular access (VA) is the life-line for children with kidney failure (KT) on hemodialysis (HD). The European Society for Paediatric Nephrology Dialysis Working Group suggested that children requiring HD start with a functioning arteriovenous fistula (AVF) but a tunnelled catheter (TC) can be placed instead where a short period on HD is anticipated before kidney transplantation (KT) (NDT 2019; 34: 1746–1765). Aims To analyze the type of VA used by incident and prevalent KF pediatric patients (pts) treated with HD in Catalonia Method Data from the Catalan Renal Registry of KF pts younger than 18 years of age undergoing kidney replacement therapy (KRT) were examined for a 22-year period. Results The modality of KRT used by incident KF pediatric pts has changed significantly over time: the percentage of children who started KRT through HD decreased progressively from 89.9% during the 1984-1989 period to 38.2% during the 2014-2018 period and, conversely, the percentage of children who started KRT by using pre-emptive KT increased progressively from 5.1% to 42.6% between the same periods (for both comparisons, p<0.001). During 2018, 18 children started KRT (rate: 12.8 per milion of population, pmp) by using pre-emptive KT (n=8, 44.4%), peritoneal dialysis (n=5, 27.8%) or HD (n=5, 27.8%). From 1997 to 2018, 112 KF pediatric pts started KRT by using HD (mean age 9.4±6,0 yr, male 58.9%, glomerular disease 36.8%). Most children started HD through an AVF during the 1997-2001 period (56.5%) but this percentage decreased over time and no children used an AVF for starting HD during the 2012-2018 period. On the contrary, the percentage of children starting HD through a TC increased progressively from 8.7% to 72.2% between the same periods (for both comparisons, p<0.001). No significant changes over time were recorded regarding untunnelled catheter (UC) utilization from 34.8% (1997-2001 period) to 27.8% (2012-2018 period) (p=0.57). Considering two age groups (0-6 vs 7-18 years), VA distribution was the following (%): 23.3 vs 76.7 for UC, 47.2 vs 52.8 for TC and 26.3 vs 73.7 for AVF (p=0.058). Regarding KF presentation, UC was used mainly to initiate HD in crashlanders (53.3%) and AVF was used mainly to start HD in children with steady kidney disease progression (63.2%) (p=0.003). The KRT modality of using prevalent KF pediatric pts has also changed significantly over time: pts on HD decreased from 34.9% (n=15, mean age 13.5 yr) in 1997 to 4.7% (n=5, mean age 11.6 yr) in 2018 and, conversely, pts with a kidney graft increased from 62.8% (n=27, mean age 13.7 yr) to 92.4% (n=98, mean age 11.2 yr) during the same period (for both comparisons, p<0.001). The percentage of children dialyzed through an AVF decreased progressively from 1997 (100%) to 2018 (0%) (p<0.001). All prevalent HD pts were dialyzed through a catheter in 2018. The KT rate increased significantly from 5.4 pmp (n=6) in 1997 to 17.1 pmp (n=24) in 2018 (p=0.007). The median time on HD (months) prior to the first KT decreased progressively from 23.1 during the 1984-1989 period to 6.6 during the 2014-2018 period (p<0.001). Conclusions 1) The VA profile of pediatric population treated with HD in Catalonia has radically changed over time. 2) Since 2012, AVF has practically disappeared as the VA in the incident and prevalent pediatric population on HD. 3) Almost all children treated by HD since 2012 were dialyzed through a catheter due to the short waiting time before receiving a kidney graft. 4) The high KT rate was a determining factor in choosing the AV type in the pediatric population treated with HD in Catalonia.

MO1022CENTRAL VENOUS CATHETERS FIRST - THE ACHILLES’ HEEL IN PEDIATRIC HEMODIALYSIS VASCULAR ACCESS

Background and Aims Management of children with end-stage kidney disease (ESKD) requiring dialysis is always challenging and particular concerns exists regarding vascular access. International reports through the years are not satisfactory, with a high rate of central venous catheter (CVC), when “Fistula First” is the goal in Hemodialysis (HD). Suggested reasons for this phenomenon include, for example, age-related anatomical limitations, shorter awaiting times for or “scheduled” transplantation, pain and anxiety related to punctures or lack of pediatric/surgical expertise. Here we present the results of the last 13 years of experience in pediatric HD vascular access from a reference center in northern Portugal. Method A retrospective descriptive study of patients admitted to our pediatric HD Unit between January 2007 and December 2020. Clinical data was collected from medical records. Results 40 patients were enrolled, mainly boys (n=22, 55%), mean age at admission 10.9±5.3 years (1-17 years), 63% weighing more than 30 kg (n =25) and 15% less than 15kg (n=6). More than half were incident patients starting on HD (n=22, 55%), 42.5% were transferred from peritoneal dialysis (PD) and one patient had a previous kidney transplant (KT). Regarding CKD etiology, 52.5% (n=21) were mainly due to congenital anomalies of the kidney and urinary tract; chronic glomerulonephritis was responsible for 20% of cases (n=8). Most patients initiated HD with a CVC (n=35, 87.5%), including two patients with an arteriovenous fistula (AVF) who required a temporary CVC until fistula maturation. At the end of follow-up, about 45% of the patients ended up with an AVF (comparing to 17.5% at the beginning) and, not unexpectedly, 88.9% (n=16) of them weighed more than 30kg and only one child less than 15 kg. The mean duration of dialysis was 1.2±1.8 years (1 month-8 years); 24 patients were submitted to KT (60%), 6 transferred to PD (15%) and only 4 remain on HD. Average waiting times for KT are quite longer in patients with AFV (1.7±2 years), in comparison to CVC (0.4±0.3 years). Conclusion CVC is by far the most used access in incident patients starting on HD. In our center it seems justified by the anatomical limitations of younger and smaller patients, as wells as expected shorter awaiting time for KT. Infectious and mechanical complications must be weighed when using CVC, mainly considering the probable need for different renal replacing techniques over the years. Although our data is quite similar to several international reports and other center experiences, we still aim for the best, with an expected improvement of these results within the coming years. For now, a notable increase in AVF placement at the end of the follow-up is already an encouraging fact.

Left Ventricular Strain and Left Atrial Strain Are Impaired During Hemodialysis in Children

Purpose We aimed to investigate intradialytic changes in ventricular and atrial function using speckle tracking echocardiography (STE) in pediatric hemodialysis (HD). Methods Children with HD vintage > 3 months were enrolled, and echocardiography was performed prior to, during, and after HD. STE was analyzed using GE EchoPAC. Left ventricular (LV) global longitudinal strain (GLS), strain rate (Sr), and mechanical dispersion index (MDI) were calculated as the average from 3 apical views; diastolic strain (Ds) and Sr from 4-chamber tracing; left atrial strain (LAS) and Sr from the 4- and 2-chamber views. Results A total of 15 patients were enrolled at a median age of 12 years (IQR 8, 16) and median HD vintage of 13 months (IQR 9, 25). GLS worsened during HD (-15.8 ± 2.2% vs -19.9 ± 1.9%, p < 0.001). Post-HD GLS was associated with BP decrease (coefficient = 0.62, p = 0.01). LV MDI and systolic Sr did not change. LV Ds progressively worsened (-8.4% (-9.2, -8.0) vs − 11.9% (-13.4, -10.3), p < 0.001). LAS changes at mid-HD returned to baseline post-HD. Ds, DSr, LAS, LASr were not associated with BV removal or BP decrease (p > 0.1). Conclusions Intradialytic LV strain and LAS changes consistent with subclinical systolic and diastolic dysfunction were observed during HD in children. Changes in Ds, DSr, LAS, and LASr were not associated with BP change or BV removal and may be related to the disease progression. Longitudinal study using these novel indices may unfold the effect of these subclinical changes on long-term cardiovascular health in children requiring chronic HD.

Citrate-induced local ionized calcium decrease in pediatric hemodialysis settings: An in-vitro study

Background: Citrate is instilled into the dialysis catheter to prevent clotting and to maintain patency between dialysis sessions. A significant amount of citrate leaks from the catheter at the injection time, which decreases the blood ionized calcium concentration (Ca2+) due to chelation. We aimed to evaluate the local impact of concentrated (i.e. 30%) citrate spilling on Ca2+ at the catheter tip in real-time pediatric conditions. Methods: An in-vitro model was constructed, involving an ion-selective electrode (Ca-ISE). A pre-curved catheter and the Ca-ISE were submerged in a glass vessel with the tips positioned adjacent to each other. The vessel was filled with 30 and 80 ml of normal saline with added calcium to simulate normal right atrium size in children and adults, respectively, and normal blood Ca2+. The amount of instilled citrate matched the filling volume of the catheter. Measurements were performed with 4% and 30% citrate solutions. Results: The mean Ca2+ measured at the tip of the catheter was 0.457 and 0.058 mmol/l when using 4% and 30% citrate, respectively ( p < 0.001). The mean Ca2+ recorded in 30 and 80 ml after instilling 30 % citrate was 0.058 and 0.055 mmol/l, respectively ( p = 0.878). Conclusions: The spilling of 30% citrate caused a strikingly greater decrease of Ca2+ at the catheter tip than the standard 4% citrate. The atrial volume did not influence the test results implying similar safety concerns for pediatric and adult patients. The used static experimental setting might have overestimated the spilling effect.

A Distinctive Approach to Venous Thromboembolism Treatment in a Pediatric, Hemodialysis Patient: A Case Report

Enoxaparin is a low molecular weight heparin (LMWH) that is the mainstay for treatment of pediatric patients with a venous thromboembolism, which provides better compliance compared with the use of unfractionated heparin (UFH) in long-term anticoagulation. Although data are limited in pediatric patients with renal insufficiency, enoxaparin can be used in this population. Data related to its use in hemodialysis (HD) pediatric patients is almost non-existent. A major concern for enoxaparin use in patients with renal insufficiency or for those on HD is bleeding. A few studies in adults showed an increased risk of bleeding, but the risk was similar to that of UFH when the two were compared. This case report describes the use of enoxaparin in an 8-year-old female who is on hemodialysis, without any bleeding or clotting complications. Although systematic trials are needed to support the safety and efficacy of LMWH in pediatric patients with renal dysfunction or on HD, this case will provide limited information for enoxaparin use in this population.