The Prospective Pediatric Continuous Renal Replacement Therapy (ppCRRT) Registry: Design, Development and Data Assessed

Many issues plague the pediatric ARF outcome literature, which include data only from single center sources, a relative lack of prospective study, mixture within studies of renal replacement therapy modality without stratification and inconsistent use of methods to control for patient illness severity in outcome analysis. Since January 2001, the Prospective Pediatric CRRT (ppCRRT) Registry Group has been collecting data from multiple United States pediatric centers to obtain demographic data regarding pediatric patients who receive CRRT, assess the effect of different CRRT prescriptions on circuit function and evaluate the impact of clinical variables on patient outcome. The aim of the current paper is to describe the ppCRRT Registry design, review the decision process and rationale for the options chosen for the ppCRRT format and discuss the analysis plan and future projects envisioned for the ppCRRT Registry.

The Effect of Vascular Access Location and Size on Circuit Survival in Pediatric Continuous Renal Replacement Therapy: A Report from the PPCRRT Registry

Purpose

Well-functioning vascular access is essential for the provision of adequate CRRT However, few data exist to describe the effect of catheter size or location on CRRT performance in the pediatric population.

Methods

Data for vascular access site, size, and location, as well as type of anticoagulant used and patient demographic data were gathered from the ppCRRT registry. Kaplan-Meier curves were generated and then analyzed by log-rank test or Cox Proportional Hazards model.

Results

Access diameter was found to significantly affect circuit survival. None of the 5 French catheters lasted longer than 20 hours. Seven and 9 French, but not 8 French, catheters fared worse than larger diameter catheters (p=0.002). Circuits associated with internal jugular access survived longer than subclavian or femoral access associated circuits (p<0.05). Circuit survival was also found to be favorably associated with the CVVHD modality (p<0.001).

Conclusions

Functional CRRT circuit survival in children is favored by larger catheter diameter, internal jugular vein insertion site and CVVHD. For patients requiring catheter diameters less than 10 French, CRRT circuit survival might be optimized if internal jugular vein insertion is feasible. Conversely, when a vascular access site other than the internal jugular vein is most prudent, consideration should be given to using the largest diameter catheter appropriate for the size of the child. The CVVHD modality was associated with longer circuit survival, but the mechanism by which this occurs is unclear.

Bartter syndrome: presentation in an extremely premature neonate

Reports of Bartter syndrome in premature neonates are rare. We describe the presentation and clinical course of a neonate born at 25.6 weeks estimated gestational age with polyuria, hyponatremia, hypokalemia and hypercalciuria ,who was diagnosed with neonatal Bartter syndrome. The evaluation, diagnosis and management of neonatal Bartter syndrome in this premature neonate are discussed.

Vasopressin-elicited water and urea permeabilities are altered in IMCD in hypercalcemic rats

To investigate how hypercalcemia blunts renal concentrating ability, alterations in basal and arginine vasopressin (AVP)-elicited osmotic water (Pf) and urea (Purea) permeabilities were measured in isolated perfused terminal inner medullary collecting ducts (IMCD) from control and chronically hypercalcemic rats after dihydrotachysterol (DHT) (M. Levi, L. Peterson, and T. Berl. Kidney Int. 23: 489-497, 1983) treatment. The IMCD Pf of DHT-treated rats did not increase significantly after AVP and was accompanied by a significant 87 +/- 4% reduction in aquaporin-2 (AQP-2) protein but not mRNA. In contrast, both basal and AVP-elicited IMCD Purea from DHT rats were significantly increased and accompanied by a significant 41 +/- 11% increase in AVP-regulated urea transporter protein content. Immunoblotting with anti-calcium/polyvalent cation-sensing receptor protein (CaR) antiserum revealed specific alterations in CaR bands in endosomes purified from the apical membranes of inner medulla of DHT rats. These data are the first detailed analyses of hypercalcemia-induced alterations in AVP-regulated permeabilities and membrane transporters in IMCD. We conclude that selective alterations in IMCD transport occur in hypercalcemia, permitting the body to dispose of excess calcium without forming calcium-containing renal stones.

Immune response to Escherichia coli O157:H7 in hemolytic uremic syndrome following salmonellosis

Escherichia coli O157:H7, a Shiga-like toxin (SLT)-producing enteric pathogen, has been implicated in most cases of post-diarrheal hemolytic uremic syndrome (D + HUS). Infection with other bacterial pathogens such as Salmonella has also preceded D + HUS episodes, leading to speculation that these organisms may also be etiological. We present two children with unrelated D + HUS following salmonellosis. Both children had negative stool cultures on sorbitol-MacConkey agar soon after the onset of diarrhea. After the diagnosis of HUS, both patients had repeat stool cultures positive for Salmonella alone. Polymerase chain reactions for SLT I and II gene sequences in Salmonella isolates were negative. Enzyme-linked immunosorbent assay for specific humoral response to E. coli O157:H7 lipopolysaccharide in acute and convalescent serum samples revealed evidence of heretofore undetected E. coli O157:H7 infection contemporaneous with each D + HUS episode. These cases demonstrate that isolation of only non-SLT-producing microbes from children with D + HUS should raise suspicion of concurrent undetected infection with SLT-producing organisms. Assaying specific immune response to E. coli O157:H7 can be an important epidemiological adjunct. Bacterial infection with non-SLT-producing Salmonella may represent concomitant enteric pathology rather than D + HUS-instigating infection.