Renal Replacement Therapy Modalities in Critically Ill Children.

OBJECTIVES: The objective of this study is to describe the relative frequency of use of continuous renal replacement therapy, intermittent hemodialysis, and peritoneal dialysis and to analyze characteristics and outcomes of critically ill children receiving renal replacement therapies admitted to PICUs that participate in the Virtual PICU (VPS LLC, Los Angeles, CA) registry. DESIGN: Retrospective, database analysis. SETTING: PICUs that participate in the Virtual PICU (VPS LLC) registry. PATIENTS: Critically ill children admitted to PICUs that participate in the Virtual PICU (VPS LLC) registry and received renal replacement therapy from January 1, 2009, to December 31, 2015. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 7,109 cases (53% males) received renal replacement therapy during the study period. The median age was 72.3 months (interquartile range, 8.4-170 mo) and median length of stay was 8.7 days (interquartile range, 3.3-21.2 d). Caucasians comprised 42% of the cohort and blacks and Hispanics were 16% each. Continuous renal replacement therapy was used in 46.5%, hemodialysis in 35.5% and peritoneal dialysis in 18%. Of the 7,109 cases, 1,852 (26%) were postoperative cases (68% cardiac surgical) and 981 (14%) had a diagnosis of cancer. Conventional mechanical ventilation was used in 64%, high-frequency oscillatory ventilation in 12%, noninvasive ventilation in 24%, and extracorporeal membrane oxygenation in 5.8%. The overall mortality was 22.3%. Patients who died were younger 40.8 months (interquartile range, 1.5-159.4 mo) versus 79.9 months (interquartile range, 12.6-171.7 mo), had a longer length of stay 15 days (interquartile range, 7-33 d) versus 7 days (interquartile range, 3-18 d) and higher Pediatric Index of Mortality 2 score -2.84 (interquartile range, -3.5 to -1.7) versus -4.2 (interquartile range, -4.7 to -3.0) (p < 0.05). On multivariate logistic regression analysis, higher mortality was associated with the presence of cancer (32.7%), previous ICU admission (32%), requiring mechanical ventilation (33.7%), receiving high-frequency oscillatory ventilation (67%), or extracorporeal membrane oxygenation (58.4%), admission following cardiac surgical procedure (29.4%), and receiving continuous renal replacement therapy (38.8%), and lower mortality was associated with hemodialysis (9.8%), and peritoneal dialysis (12.3%) (p < 0.0001). CONCLUSIONS: Continuous renal replacement therapy is an increasingly prevalent renal replacement therapy modality used in critically ill children admitted to an ICU. Higher mortality rate with the use of continuous renal replacement therapy should be interpreted with caution.

Cytokine and chemokine patterns across 100 days after hematopoietic stem cell transplantation in children.

We mapped the cytokine response to hematopoietic stem cell transplantation (HSCT) by assaying 51 cytokines and chemokines each week for 100 days in 51 children receiving allogeneic (n = 44) or autologous HSCT (n = 7). Assay values were reported as mean fluorescence intensity (MFI). Log transformation converted MFI to clinically relevant measures (ie, pg/mL). We searched for potential markers of transplant complications by using mixed treatment by subject analysis of variance. Global cytokine secretion in HSCT recipients was significantly lower than in concurrent control patients (n = 11). Coincident with the nadir in WBC count, the concentration of many cytokines declined further by the second and third week. All analytes (except monokine induced by gamma interferon [MIG]) subsequently rebounded by week 4 (coincident with engraftment and recovery of WBC count) but often still remained well below control levels. Concurrent with the collective nadir of multiple cytokines, monocyte chemoattractant protein 1 (MCP-1), growth-regulated oncogene alpha (GRO-a), and leptin surged during weeks 2 to 4. High levels of leptin persisted throughout the 100 post-transplant days. Also during weeks 2 to 4, hepatocyte growth factor (HGF) and IL-6 surged in children with complications but not in those without complications. The peak in HGF was more pronounced in veno-occlusive disease (VOD). HGF and IL-6 secretion rose at least 2 weeks before the clinical diagnosis of VOD or graft-versus-host disease (GVHD). From week 4 onward in all groups, the MFI of the cytokine resistin increased to 5 to 15 times above concurrent control. HGF has now emerged in 3 or more biomarker discovery efforts for GVHD (and in our population for VOD as well). HGF (with or without IL-6) should be investigated as a potential predictive biomarker of VOD or GVHD. Alternatively, the hyperinflammatory "signature" provided by a multicytokine assay may be predictive.

Acute kidney injury in pediatric stem cell transplant recipients.

Because respiratory dysfunction after hematopoietic stem cell transplantation is a manifestation of a continuum of dysfunction temporarily induced by the transplant process, a proactive rather than reactive approach might prevent or attenuate its progression to acute respiratory distress syndrome. Organ dysfunction in this population results from cytokine-driven processes, of which the first manifestation includes fluid accumulation. We describe a multistep protocol that first targets fluid balance control, both through restriction of intake and through augmentation of output using dopamine and furosemide infusions. If these steps fail to stem the tide of water accumulation, we advocate the relatively early use of continuous renal replacement therapy, its use triggered by a continued increase in body weight (>10% above baseline), an increasing c-reactive protein level, and an increasing oxygen need. Renal function parameters do not figure in this protocol. We recommend continuous renal replacement therapy at 35 mL/kg/h (2,000 mL/1.73 m(2)/h), a dose that allows adequate flexibility in fluid management and that may provide effective clearance of proinflammatory (and anti-inflammatory) mediators that drive the evolving dysfunction. Proactive intervention improves the clinical status such that the transition to mechanical ventilation may proceed smoothly or in some cases even may be avoided altogether.

Post hoc analysis of calfactant use in immunocompromised children with acute lung injury: Impact and feasibility of further clinical trials.

OBJECTIVE: To assess the impact of calfactant (a modified natural bovine lung surfactant) in immunocompromised children with acute lung injury and to determine the number of patients required for a definitive clinical trial of calfactant in this population. DESIGN: Post hoc analysis of data from a previous randomized, control trial. SETTING: Tertiary care pediatric intensive care units. PATIENTS: All children, defined as immunocompromised, enrolled in a multicenter, masked, randomized, control trial of calfactant for acute lung injury conducted between July 2000 and July 2003. INTERVENTIONS: Patients received either an intratracheal instillation of calfactant or an equal volume of air placebo in a protocolized manner. MEASUREMENTS AND MAIN RESULTS: Eleven of 22 (50%) calfactant-treated patients died when compared with 18 of 30 (60%) placebo patients (absolute risk reduction 10.0%, 95% confidence interval [CI] -17.3, 37.3). Among the 23 patients with an initial oxygen index (OI) >/=13 and

Correlation of clinical and biochemical findings with diabetic ketoacidosis-related cerebral edema in children using magnetic resonance diffusion-weighted imaging.

OBJECTIVE: To determine clinical and biochemical factors influencing cerebral edema formation during diabetic ketoacidosis (DKA) in children. STUDY DESIGN: We used magnetic resonance diffusion-weighted imaging to quantify edema formation. We measured the apparent diffusion coefficient (ADC) of brain water during and after DKA treatment in 26 children and correlated ADC changes with clinical and biochemical variables. RESULTS: Mean ADC values were elevated during DKA treatment compared with baseline (8.13 +/- 0.47 vs 7.74 +/- 0.49 x 10(-4) mm(2)/sec, difference in means 0.40, 95% CI: 0.25 to 0.55, P < .001). Children with altered mental status during DKA had greater elevation in ADC. ADC elevation during DKA was positively correlated with initial serum urea nitrogen concentration (correlation coefficient 0.41, P = .03) and initial respiratory rate (correlation coefficient 0.61, P < .001). ADC elevation was not significantly correlated with initial serum glucose, sodium or effective osmolality, nor with changes in glucose, sodium or osmolality during treatment. Multivariable analyses identified the initial urea nitrogen concentration and respiratory rate as independently associated with ADC elevation. CONCLUSIONS: The degree of edema formation during DKA in children is correlated with the degree of dehydration and hyperventilation at presentation, but not with factors related to initial osmolality or osmotic changes during treatment. These data support the hypothesis that CE is related to cerebral hypoperfusion during DKA, and that osmotic fluctuations during DKA treatment do not play a primary causal role.

Elevated serum amylase and lipase in pediatric diabetic ketoacidosis.

OBJECTIVES: Pancreatic enzyme concentrations are frequently elevated in children with diabetic ketoacidosis (DKA). We sought to determine the clinical and biochemical characteristics associated with patients with these elevations. Our hypothesis was that pancreatic enzyme elevations would be associated with biochemical markers of hypoperfusion. DESIGN: Prospective cohort study. SETTING: Three university-affiliated children's hospitals. PATIENTS: We collected data on consecutive children <18 yrs of age hospitalized with the diagnosis of DKA. INTERVENTIONS: Serum electrolyte and lactate concentrations and venous pH and Pco2 were measured every 3 hrs from hours 0 to 12 and then every 6 hrs until hour 24. Serum calcium, phosphate, and magnesium concentrations were measured every 6 hrs from hours 0 to 24. Serum amylase, lipase, and triglyceride concentrations were measured at hour 0 and then 12, 24, and 48 hrs after the initiation of therapy. MEASUREMENTS AND MAIN RESULTS: We performed multivariable analyses to test for associations between clinical variables and pancreatic enzyme elevation in 67 children with DKA. Lipase was elevated in 21 (31%) and amylase in 16 (24%) of the children. Pancreatic enzyme values peaked 12-24 hrs after admission. There was no significant correlation between pancreatic enzyme elevation and abdominal pain. In multivariable analyses, an elevated blood urea nitrogen (BUN) concentration was associated with elevated serum amylase (odds ratio 1.04 per unit increase; 95% confidence interval, 1.01-1.09; p = .02), and elevated BUN concentrations and hypophosphatemia were associated with elevated serum lipase (odds ratio 1.04 per unit increase; 95% confidence interval, 1.00-1.08; p = .04; and odds ratio 0.35 per unit increase; 95% confidence interval, 0.15-0.81; p = .01, respectively). CONCLUSIONS: Elevation of pancreatic enzymes is common in children with DKA, but clinical pancreatitis is rare. Pancreatic enzyme levels reach a peak 12-24 hrs after initiation of treatment for DKA. Pancreatic enzyme elevation is associated with increased BUN concentrations at presentation but is not associated with abdominal pain.

Clinical review: alternative vascular access techniques for continuous hemofiltration.

Obtaining or maintaining vascular access for continuous hemofiltration can sometimes be problematic, especially in the child or adult in multiple organ failure with edema and/or coagulopathy. Problems commonly encountered include obstruction of the femoral vein by the catheter, insertion difficulties, safety concerns when cannulating the subclavian vein in coagulopathy, and catheter and circuit occlusion due to disseminated intravascular coagulation. For access in infants we describe a technique utilizing two single-lumen thin-walled vascular sheaths. For infants and small children initial access to the vein may be difficult due to edema or poor perfusion. For this situation we describe the 'mini-introducer' technique of securing the vein and facilitating subsequent insertion of a relatively large guide wire. At any age an alternative route to the subclavian vein, from above the clavicle, is potentially 'compressible' in the event of hemorrhage during the procedure. We remind the reader of the utility of ultrasound guidance for cannulation of the internal jugular and subclavian veins. And lastly we review the options for venous return via the umbilical vein in infants, and via the antecubital vein in larger children and adults.

The hemophagocytic syndrome: titrating continuous hemofiltration to the degree of lactic acidosis.

In 3 cases of severe multiple organ failure due to hemophagocytic lymphohistiocytosis (HLH) in children, the authors demonstrate the utility of continuous hemofiltration in attenuating the consequences of excess cytokine activity, with therapy titrated to the degree of lactic acidosis. HLH was diagnosed in 3 encephalopathic children with multiple organ failure, elevated ferritin (49,396-237,582 pmol/L; or 21,983-105,733 ng/mL), elevated serum triglyceride, and depressed cell lines. One had a known malignancy, one had EBV-associated lymphoproliferative disease, and one was previously healthy. Continuous hemofiltration was initiated, with the ultrafiltrate production rate and countercurrent dialysate flow titrated to metabolic acidosis as reflected by the serum lactate (maximum 3.5 mmol/L or 31.6 mg/dL). Hemofiltration was titrated upward until lactic acidosis resolved, through clearance of lactate or interruption of excess cytokine-driven activity; maximum prescription was 2000 mL/h ultrafiltrate production plus 2500 mL/h dialysate flow. Stability was achieved with hemofiltration, then substantial resolution occurred with treatment according to the HLH-94 protocol (dexamethasone, cyclosporin, VP-16, intrathecal methotrexate). One child succumbed to candidiasis. Another made a full recovery. A third succumbed to his primary malignancy. HLH should be suspected in unexplained or unresolving multiple organ failure. Titration of hemofiltration based on measurable parameters of cellular metabolism (e.g., lactate, base deficit) may stabilize the child with metabolic acidosis long enough to allow proper diagnosis and institution of definitive therapy. Hemofiltration is not a panacea but rather a stabilizing mechanism, with poorly understood effects on interstitial water and solute flux, that facilitates recovery over weeks, not days.

Frequency of sub-clinical cerebral edema in children with diabetic ketoacidosis.

Symptomatic cerebral edema occurs in approximately 1% of children with diabetic ketoacidosis (DKA). However, asymptomatic or subclinical cerebral edema is thought to occur more frequently. Some small studies have found narrowing of the cerebral ventricles indicating cerebral edema in most or all children with DKA, but other studies have not detected narrowing in ventricle size. In this study, we measured the intercaudate width of the frontal horns of the lateral ventricles using magnetic resonance imaging (MRI) in children with DKA during treatment and after recovery from the DKA episode. We determined the frequency of ventricular narrowing and compared clinical and biochemical data for children with and without ventricular narrowing. Forty-one children completed the study protocol. The lateral ventricles were significantly smaller during DKA treatment (mean width, 9.3 +/- 0.3 vs. 10.2 +/- 0.3 mm after recovery from DKA, p < 0.001). Children with ventricular narrowing during DKA treatment (22 children, 54%) were more likely to have mental status abnormalities than those without narrowing [12/22 vs. 4/19 with Glasgow Coma Scale (GCS) scores below 15 during therapy, p = 0.03]. Multiple logistic regression analysis revealed that a lower initial PCO2 level was significantly associated with ventricular narrowing [odds ratio (OR) = 0.88, 95% confidence interval (95% CI) = 0.78-0.99, p = 0.047). No other variables analyzed were associated with ventricular narrowing in the multivariate analysis. We conclude that narrowing of the lateral ventricles is evident in just over half of children being treated for DKA. Although children with ventricular narrowing did not exhibit neurological abnormalities sufficient for a diagnosis of 'symptomatic cerebral edema', mild mental status abnormalities occurred frequently, suggesting that clinical evidence of cerebral edema in children with DKA may be more common than previously reported.

Detection of cerebral {beta}-hydroxy butyrate, acetoacetate, and lactate on proton MR spectroscopy in children with diabetic ketoacidosis.

BACKGROUND AND PURPOSE: Ketone bodies provide important alternate fuel for brain metabolism, and their transport into the brain increases with prolonged fasting. During diabetic ketoacidosis (DKA), serum ketone concentrations markedly increase; however, little is known about whether ketone bodies accumulate in cerebral tissues during DKA. We used proton MR spectroscopy (MRS) to detect cerebral beta-hydroxy butyrate (betaOHB) and acetone/acetocaetate (AcAc) in children with DKA. METHODS: Twenty-five children underwent brain MRS: nine within 4 hours of the start of treatment for DKA; 11, at 4-8 hours; and five, at 8-12 hours. MRS was repeated after their recovery from the DKA episode at > or =72 hours after the start of treatment. MRS was evaluated for peaks corresponding to betaOHB (doublet centered on 1.20 ppm) and lactate (doublet centered on 1.33 ppm). Difference spectroscopy was used to identify the AcAc peak at 2.22-2.26 ppm. RESULTS: betaOHB was detected in 13 children (52%), more frequently within 4 hours (eight children, 89%) than after 4 hours (five children, 31%). AcAc was detected in 15 children (60%), more frequently at >4 hours after the start of treatment (12 patients, 75%) than in the first 4 hours (three patients, 33%). Lactate was detected in five children (18%), all within the first 8 hours of treatment. CONCLUSION: In children, betaOHB and AcAc accumulate in the brain during DKA, and they can be detected on MRS. Care should be taken in interpreting MRS results in patients with DKA to avoid erroneously attributing betaOHB peaks to lactate.

Effect of exogenous surfactant (calfactant) in pediatric acute lung injury: a randomized controlled trial.

CONTEXT: Despite evidence that patients with acute lung injury (ALI) have pulmonary surfactant dysfunction, trials of several surfactant preparations to treat adults with ALI have not been successful. Preliminary studies in children with ALI have shown that instillation of a natural lung surfactant (calfactant) containing high levels of surfactant-specific protein B may be beneficial. OBJECTIVE: To determine if endotracheal instillation of calfactant in infants, children, and adolescents with ALI would shorten the course of respiratory failure. DESIGN, SETTING, AND PATIENTS: A multicenter, randomized, blinded trial of calfactant compared with placebo in 153 infants, children, and adolescents with respiratory failure from ALI conducted from July 2000 to July 2003. Twenty-one tertiary care pediatric intensive care units participated. Entry criteria included age 1 week to 21 years, enrollment within 48 hours of endotracheal intubation, radiological evidence of bilateral lung disease, and an oxygenation index higher than 7. Premature infants and children with preexisting lung, cardiac, or central nervous system disease were excluded. INTERVENTION: Treatment with intratracheal instillation of 2 doses of 80 mL/m2 calfactant or an equal volume of air placebo administered 12 hours apart. MAIN OUTCOME MEASURES: Ventilator-free days and mortality; secondary outcome measures were hospital course, adverse events, and failure of conventional mechanical ventilation. RESULTS: The calfactant group experienced an acute mean (SD) decrease in oxygenation index from 20 (12.9) to 13.9 (9.6) after 12 hours compared with the placebo group's decrease from 20.5 (14.7) to 15.1 (9.0) (P = .01). Mortality was significantly greater in the placebo group compared with the calfactant group (27/75 vs 15/77; odds ratio, 2.32; 95% confidence interval, 1.15-4.85), although ventilator-free days were not different. More patients in the placebo group did not respond to conventional mechanical ventilation. There were no differences in long-term complications. CONCLUSIONS: Calfactant acutely improved oxygenation and significantly decreased mortality in infants, children, and adolescents with ALI although no significant decrease in the course of respiratory failure measured by duration of ventilator therapy, intensive care unit, or hospital stay was observed.

Mechanism of cerebral edema in children with diabetic ketoacidosis.

OBJECTIVES: Cerebral edema during diabetic ketoacidosis (DKA) has been attributed to osmotic cellular swelling during treatment. We evaluated cerebral water distribution and cerebral perfusion during DKA treatment in children. STUDY DESIGN: We imaged 14 children during DKA treatment and after recovery, using both diffusion and perfusion weighted magnetic resonance imaging (MRI). We assessed the apparent diffusion coefficients (ADCs) and measures reflecting cerebral perfusion. RESULTS: The ADC was significantly elevated during DKA treatment (indicating increased water diffusion) in all regions except the occipital gray matter. Mean reductions in the ADC from initial to postrecovery MRI were: basal ganglia 4.7 +/- 2.5 x 10(-5) mm(2)/s (P=.002), thalamus 3.7 +/- 2.8 x 10(-5) mm(2)/s, (P=.002), periaqueductal gray matter 4.3 +/- 5.1 x 10(-5) mm(2)/s (P=.03), and frontal white matter 2.0 +/- 3.1 x 10(-5) mm(2)/s (P=.03). In contrast, the ADC in the occipital gray matter increased significantly from the initial to postrecovery MRI (mean increase 3.9 +/- 3.9 x 10(-5) mm(2)/s, P=.004). Perfusion MRI during DKA treatment revealed significantly shorter mean transit times (MTTs) and higher peak tracer concentrations, possibly indicating increased cerebral blood flow (CBF). CONCLUSIONS: Elevated ADC values during DKA treatment suggests a vasogenic process as the predominant mechanism of edema formation rather than osmotic cellular swelling.

Continuous veno-venous hemofiltration may improve survival from acute respiratory distress syndrome after bone marrow transplantation or chemotherapy.

PURPOSE: Acute respiratory distress syndrome (ARDS) may result from immunologic activity triggered by irradiation and/or chemotherapy. Hemofiltration removes plasma water and soluble components below 25 kilodaltons. The authors hypothesized that early hemofiltration might attenuate the inflammatory component of ARDS, resulting in increased survival in immunocompromised children and young adults. METHODS: Ten children (6 bone marrow transplantation, 3 chemotherapy, 1 lymphoma/hemophagocytosis) with ARDS (Pao2/Fio2 94 +/- 37 torr) received early continuous veno-venous hemodiafiltration as adjunctive therapy for respiratory failure, regardless of renal function. Six children had normal urine output and initial serum creatinine (range 0.1-1.2 mg/dL); four had renal insufficiency (initial creatinine 1.7-2.4 mg/dL). Hemofiltration was instituted coincident with intubation. Respiratory failure was precipitated by Enterobacter sepsis in two patients and by Aspergillus in one. RESULTS: Hemodiafiltration was performed for 13 +/- 9 days. A high rate of clearance was achieved (52 +/- 17 mL/min/1.73 m2). Duration of mechanical ventilation was 14 +/- 9 days. Nine of the 10 children were successfully extubated; 8 survived. CONCLUSIONS: Early hemofiltration may improve survival from ARDS following bone marrow transplantation or chemotherapy. Possible mechanisms include strict fluid balance, immunomodulation through filtration of inflammatory constituents, and immunomodulation through intensive extracellular water exchange that delivers biochemicals to organs of metabolism as well as the hemofilter.