Aquapheresis (AQ) in Tandem with Extracorporeal Membrane Oxygenation (ECMO) in Pediatric Patients

Children with cardiopulmonary failure requiring extracorporeal membrane oxygenation (ECMO) are at risk for fluid overload (FO) despite the normal estimated glomerular filtration rate (eGFR). It has been shown that survival in the intensive care unit (ICU) is inversely proportional to FO. Therefore, fluid removal, or prevention of FO, in these critical cases has the potential to improve survival. Aquapheresis (AQ), a procedure used for fluid removal, with success in patients with heart failure has also been used in children with acute oliguric kidney injury (AKI), to prevent and treat FO. The purpose of this article was to describe the use of Aquadex FlexFlow^® for AQ in pediatric patients on ECMO, as a means to provide a simplified and safe form of fluid removal with minimal impact on ECMO therapy. The principal variables collected include patients' demographics, urine output, serum creatinine, withdrawal and infusion pressures, ultrafiltration (UF) rates, and ECMO flow ranges, along with length of stay in pediatric ICU and survival. Patient survival was 100% with preserved eGFR. The ECMO flows were not affected by AQ. Urine output decreased somewhat during therapy, with little AQ machine pressure variations. Range of UF tolerated without hemodynamic abnormalities was 1.24-6.2 mL/kg/h, allowing the patients to maintain their pre-AQ body weight, while receiving intravenous (IV) nutrition and medications. This article describes the use of AQ in tandem with ECMO in a user-friendly and safe way to provide UF in children requiring cardiopulmonary support, with minimal flow and hemodynamic disturbance.

Non-enteropathic hemolytic uremic syndrome: causes and short-term course

BACKGROUND

Nondiarrheal or Streptococcus pneumoniae-related hemolytic uremic syndrome (HUS) represents a heterogeneous group of disorders. This study was performed to: (1) describe the current incidence, causes, demographic features, hospital courses, and short-term outcomes of non-enteropathic HUS; (2) compare findings in patients with non-enteropathic HUS with those obtained from a contemporaneous cohort of children with enteropathic or diarrhea-associated HUS (D+ HUS) diagnosed and treated at the same clinical sites; and (3) identify clinical or laboratory features that differentiate these 2 groups and predict disease severity and the short-term outcome in patients with non-enteropathic HUS.

METHODS

Data were collected from patients screened between 1997 and 2001 for enrollment in a multicenter trial of SYNSORB Pk (SYNSORB Biotech Inc, Calgary, Alberta, Canada) in D+ HUS, but who were ineligible because of lack of a diarrhea prodrome. The following features were recorded: age; sex; ethnicity; prodromal symptoms; cause; nadir values for hemoglobin, hematocrit, and platelet count; use of dialysis; and length of hospitalization.

RESULTS

Twenty-seven of 247 children with HUS had non-enteropathic HUS (11%). Twenty-four patients (15 boys, 9 girls), whose medical records were complete and available for review, comprise the study cohort. Mean age at onset was 4.2 +/- 0.9 (SE) years. Infection caused by S pneumoniae was diagnosed in 9 patients (38%). Dialysis was performed in 17 patients (71%) for 40 +/- 27 days. Median length of hospitalization was 22 days (range, 2 to 71 days). Children with S pneumoniae-related HUS had a longer hospital stay than those with other causes of non-enteropathic HUS, but all patients with S pneumoniae-related HUS recovered kidney function. Dialysis therapy was required more often (17 of 24 versus 59 of 145 children; P = 0.025) and hospital stays were longer (median, 22 versus 9 days; P = 0.002) in children with non-enteropathic HUS compared with patients with D+ HUS who were enrolled in the SYNSORB Pk clinical trial.

CONCLUSION

(1) The incidence of non-enteropathic HUS is approximately one tenth that of D+ HUS; (2) patients with non-enteropathic HUS require dialysis therapy more often and are hospitalized more than twice as long during the acute episode compared with those with D+ HUS; (3) infection caused by S pneumoniae accounts for nearly 40% of cases of non-enteropathic HUS; and (4) although S pneumoniae-related HUS is associated with a less favorable short-term course than other types of non-enteropathic HUS or D+ HUS, the long-term prognosis for recovery of renal function appears to be good in these patients.

Sirolimus lowers myeloperoxidase and p-ANCA titers in a pediatric patient before kidney transplantation

We report the case of a child with microscopic polyangiitis (myeloperoxidase-antineutrophil cytoplasmic antibody [p-ANCA]-positive vasculitis) whose disease progressed to end-stage renal failure, in whom sirolimus contributed to normalization of myeloperoxidase and ANCA titers. The disease course, various therapies, and outcome are discussed, as is the rationale for using sirolimus.

Na(+)-K(+)-ATPase-mediated basolateral rubidium uptake in the maturing rabbit cortical collecting duct

Within the renal cortical collecting duct (CCD), transepithelial Na(+) absorption and K(+) secretion are linked to basolateral Na(+)-K(+)-ATPase activity. Our purpose was to examine the developmental changes in basolateral Na(+)-K(+)-ATPase-mediated (86)rubidium (Rb) uptake, its inhibitor sensitivity and relationship to pump hydrolytic activity and Na(+) transport. Multiple CCDs ( approximately 6 mm) from maturing rabbits were affixed to coverslips, preincubated at 37 degrees C for 10 min (+/-1-2.5 mM ouabain or 10 or 100 micro M Schering-28080, an inhibitor of H(+)-K(+)-ATPase), and then transferred to prewarmed incubation solution containing tracer amounts of (86)Rb (+/-inhibitors). After 1 min at 37 degrees C, tubular samples were rinsed and permeabilized and isotope counts were measured to calculate basolateral Rb uptake. Ouabain-inhibitable Rb uptake, an index of basolateral Na(+)-K(+) pump activity, increased approximately 3-fold during the 1st 8 wk of postnatal life (P < 0.03). The approximately 2-fold increase in absolute rate of Rb uptake between 1 and 6 wk (2.64 +/- 0.45 to 5.02 +/- 0.32 pmol. min(-1). mm(-1)) did not reach statistical significance. The rate of basolateral Rb uptake increased further after the 6th wk of life to 7.29 +/- 0.53 pmol. min(-1). mm(-1) in adult animals (P < 0.03 vs. 6 wk). Schering-28080 failed to inhibit Rb uptake, implying that functional H(+)-K(+)-ATPase is absent at the basolateral membrane. Na(+)-K(+)-ATPase hydrolytic activity, determined by using a microassay that measured inorganic phosphate release from [gamma-(32)P]ATP under maximum velocity (V(max)) conditions, also increased in the differentiating CCD (from 316.2 +/- 44.4 pmol. h(-1). mm(-1) at 2 wk to 555.9 +/- 105.1 at 4 wk to 789.7 +/- 145.0 at 6 wk; r = 1.0 by linear regression analysis; P < 0.005). The parallel approximately 2.5-fold increases in Na(+)-K(+)-ATPase activity and ouabain-sensitive Rb uptake between 2- and 6-wk postnatal age suggest that the developmental increase in basolateral transport capacity is due predominantly to an increase in enzyme abundance. The signals mediating the developmental increase in Na(+)-K(+)-ATPase activity in the CCD remain to be defined.

Predicting first-year relapses in children with nephrotic syndrome

OBJECTIVE

More than half of the children diagnosed with nephrotic syndrome will have relapses. These can be infrequent relapses (IRs: <2 in 6 months or <3 in a year) or frequent relapses (FRs: >2 in 6 months or >3 in a year). Patients who relapse while on alternate day steroids or within 1 month of discontinuation of steroid therapy are considered steroid-dependent (SD; J Pediatr. 1982; 101:514-518). Patients with an IR course have a better long-term prognosis, and many of them have minimal-change disease without mesangial hypercellularity or sclerosis. The purpose of our study was to identify factors at initial presentation that could predict the relapse pattern in the first year after diagnosis, without taking into consideration the histopathology found on renal biopsy.

DESIGN

We analyzed the medical records of children who were seen by us before March 1997 and followed for at least 1 year. Variables selected in the study were age, sex, race, presence or absence of hematuria, and days to remission (defined as protein-free) at the initial presentation, because they could relate to the pattern of relapses (ie, IR, FR, and SD).

RESULTS

Of 70 patients, 14 were excluded because of insufficient data. There were 38 males (67.9%) and 18 females (32.1%), giving a male:female ratio of 1.8:1. Median age at presentation was 3.25 years (range: 1.5-13), and 76.9% were white, 8.9% black, 7.1% Hispanic, and 7.1% other. Of all the patients, 23 were IR (41.1%), 9 were FR (16.1%), and 24 were SD (42. 9%). Median days to remission were 10 (range: 2-60), on Prednisone 60 mg/M(2) daily. Hematuria was present initially in 26 patients (46. 4%), and absent in 30 (53.6%). Age, sex, race, and hematuria, as independent variables, were not predictors of relapses in the first year. However, using a stratified analysis based on the presence or absence of hematuria, we found that if the remission occurred within the first week of therapy, the patients without hematuria were more likely to be IR. The sensitivity and specificity of this finding were 67% and 89%, respectively, with a positive predictive value of 94%.

CONCLUSION

We conclude that of all the presenting features, the rapidity of initial response to steroid therapy combined with the presence of hematuria, could predict future relapses and should be well documented.

Development of a life-threatening anaphylactoid reaction following administration of ioversol in a child

We report for the first time the case of a 3-year-old girl who developed a severe anaphylactoid reaction following the administration of the nonionic, low osmolar intravenous radiographic contrast agent ioversol. Severe reactions to ioversol have rarely been reported in adult patients and to our knowledge never in children. Health care providers managing children who may require radiologic imaging studies with ioversol should be aware of the potential complications of this radiographic contrast agent.

Nephrotic syndrome associated with hypocomplementemia in a 4-year-old boy with hemophilia B

PURPOSE

The case of a 4-year-old boy with hemophilia B with inhibitor who developed nephrotic syndrome is described. The possible association between factor IX therapy and nephrotic syndrome in patients with hemophilia B is discussed.

PATIENT AND METHODS

A chart review of a 4-year-old boy with hemophilia B and an inhibitor who developed nephrotic syndrome with transient hypocomplementemia was performed. In addition, a literature search was undertaken to determine the prevalence of this association and possible etiologic factors.

RESULTS

Although the nephrotic syndrome was resistant to steroid therapy and Bebulin (Osterreichisches Institut für Haemoderivate Ges.M.B.H., Subsidiary of Immuno AG, Vienna, Austria) infusions were continued, the edema resolved and proteinuria decreased. Seven month later, proteinuria, accompanied by transient hypocomplementemia, increased again. A rise in factor IX inhibitor level was observed. The patient received no immunosuppressive therapy, and exhibited a continuous decrease in urinary protein excretion over the following months.

DISCUSSION

A discussion about possible differential diagnoses and a review of the literature are presented.

Age dependence of tolerance to anoxia and changes in cytosolic calcium in rabbit renal proximal tubules

Calcium(Ca2+)-dependent processes mediate, in part, anoxic cell injury. These may account for the difference in sensitivity to anoxia between certain immature and mature renal cells. To address this question, we studied the effects of anoxia on cytosolic free Ca2+ concentration ([Ca2+]i), cell integrity, and transport functions in microdissected proximal convoluted tubules (PCT) of < 3-week-old (newborn) and > 12-week-old (adult) rabbits. Tubules were loaded with 10 microM fura-2 AM by incubation for 60 min at 37 degrees C, and then superfused with isosmotic saline solution gassed with either 95%O2-5%CO2 (control group) or 95%N2-5%CO2 (anoxia group) for 30 min. [Ca2+]i was measured ratiometrically; cell damage was assessed by nuclear binding of propidium iodide (PI). Anoxia resulted in a fourfold increase in [Ca2+]i in adult tubules (from resting values of 245 +/- 10 to 975 +/- 100 nM, P < 0.001), whereas in newborn tubules the rise was significantly less (from resting values of 137 +/- 5 to 165 +/- 5 nM, P < 0.001 between anoxic groups). Transient exposure to 100 mM potassium chloride, which depolarizes the PCT cells, induced increases in [Ca2+]i from baseline, to 920 +/- 90 nM in tubules from adult and to 396 +/- 16 nM in those from newborn rabbits (P < 0.001 between age groups). After exposure to ligands such as parathyroid hormone (PTH) and ATP, [Ca2+]i increased in both newborn and adult tubules, but to lower levels in newborn tubules. The response to PTH and ATP was transient in both age groups, [Ca2+]i returning to baseline levels after 2 min. Following anoxia, tubules from adult animals exhibited staining of all cell nuclei by 1 min exposure to PI, indicative of gross permeabilization of the cells. Nuclei of anoxic immatures tubules did not stain with PI. The sodium-dependent uptakes of a glucose analogue (14C-alpha-methyl-glucopyranoside) and phosphate (32Pi) were preserved in agarose-filled tubules of newborns after anoxia, whereas in those of adults recovery from anoxia was associated with drastic reduction in the uptake of these solutes. Overall, our results suggest that: (1) during anoxia, cell Ca2+ rises to critical levels in PCTs of adults compared with those of < 3-week-old animals, (2) Ca2+ influx occurs via a pathway activated by exposure to high [K+]o, presumably voltage-sensitive Ca2+ channels or reversal of Na(+)-Ca2+ exchange, (3) these pathways are either less active or less abundant in proximal tubules of newborn compared with adult rabbits, and (4) secondary active transport activity and cellular integrity are well preserved after anoxia in PCT cells of newborn but not of adult rabbits.