Renal replacement therapy in the treatment of confirmed or suspected inborn errors of metabolism

Severe non-hepatic hyperammonaemic encephalopathy in an immunocompromised adolescent with enterocolitis

Non-hepatic causes of hyperammonaemia are uncommon relative to hepatic aetiologies. An adolescent female was admitted to the hospital with a diagnosis of very severe aplastic anaemia. During her treatment with immunosuppressive therapy, she developed neutropenic enterocolitis, pseudomonal bacteraemia and hyperammonaemia. A combination of intermittent haemodialysis and high-volume continuous veno-venous haemodiafiltration (CVVHDF) was required to manage the hyperammonaemia. Despite a thorough investigation, there were no hepatic, metabolic or genetic aetiologies identified that explained the hyperammonaemia. The hyperammonaemia resolved only after the surgical resection of her inflamed colon, following which she was successfully weaned off from the renal support. This is a novel case report of hyperammonaemia of non-hepatic origin secondary to widespread inflammation of the colon requiring surgical resection in an immunocompromised patient. This case also highlights the role of high-volume CVVHDF in augmenting haemodialysis in the management of severe refractory hyperammonaemia.

Liver Transplantation for Acute Liver Failure Due to Yellow Phosphorus Poisoning - A Comprehensive Review

Yellow phosphorus or metal phosphide (YP-MP) rodenticide poisoning has been a known cause of acute liver failure (ALF) in many countries of Asia and North and South America over the last decade. It is a highly toxic compound and is a well-known cause of intentional or accidental poisoning in both adults and children. In lower doses, it causes gastrointestinal symptoms and mild hepatic injury, and patients may spontaneously recover. In higher doses, hepatic necrosis and fatty infiltration may cause significant injury and may even lead to ALF, characterized by hepatic encephalopathy, coagulopathy, and lactic acidosis. Cardiotoxicity, rhabdomyolysis, and neutropenia are other well-documented complications. If untreated, it may lead to multi-organ dysfunction and death. Plasmapheresis and continuous renal replacement therapy (CRRT) have been used with limited success in patients who do not recover spontaneously. However, patients who develop ALF often need liver transplantation (LT). Liver transplantation has been successfully performed in ALF due to YP-MP poisoning in several countries, with good results in both adult and pediatric patients. Separate criteria for LT are important to ensure early and rapid listing of critical patients on the waiting list. The success rates of LT for ALF due to YP-MP rodenticide poisoning are very promising, provided there are no contra-indications to transplant. Plasma exchange, CRRT, or cytosorb can be used as a bridge to transplant in selected patients. In the long term, only with an increase in public awareness and sale restrictions can we prevent the intentional and accidental poisoning caused by this easily available, highly toxic compound.

Acute hemodialysis therapy in neonates with inborn errors of metabolism

BACKGROUND

Inborn errors of metabolism (IEM), including organic acidemias and urea cycle defects, are characterized by systemic accumulation of toxic metabolites with deleterious effect on the developing brain. While hemodialysis (HD) is most efficient in clearing IEM-induced metabolic toxins, data regarding its use during the neonatal period is scarce.

METHODS

We retrospectively summarize our experience with HD in 20 neonates with IEM-induced metabolic intoxication (seven with maple syrup urine disease, 13 with primary hyperammonia), over a 16-year period, between 2004 and 2020. All patients presented with IEM-induced neurologic deterioration at 48 h to 14 days post-delivery, and were managed with HD in a pediatric intensive care setting. HD was performed through an internal jugular acute double-lumen catheter (6.5-7.0 French), using an AK-200S (Gambro, Sweden) dialysis machine and tubing, with F3 or FXpaed (Fresenius, Germany) dialyzers.

RESULTS

Median (interquartile range) age and weight at presentation were 5 (3-8) days and 2830 (2725-3115) g, respectively. Two consecutive HD sessions decreased the mean leucine levels from 2281 ± 631 to 179 ± 91 μmol/L (92.1% reduction) in MSUD patients, and the mean ammonia levels from 955 ± 444 to 129 ± 55 μmol/L (86.5% reduction), in patients with hyperammonemia. HD was uneventful in all patients, and led to marked clinical improvement in 17 patients (85%). Three patients (15%) died during the neonatal period, and four died during long-term follow-up.

CONCLUSIONS

Taken together, our results indicate that HD is safe, effective, and life-saving for most neonates with severe IEM-induced metabolic intoxication, when promptly performed by an experienced and multidisciplinary team. A higher resolution version of the Graphical abstract is available as Supplementary information.

Multisite Retrospective Review of Outcomes in Renal Replacement Therapy for Neonates with Inborn Errors of Metabolism

OBJECTIVE

To assess the outcomes of neonates in a contemporary multi-institutional cohort who receive renal replacement therapy (RRT) for hyperammonemia.

STUDY DESIGN

We performed a retrospective analysis of 51 neonatal patients with confirmed inborn errors of metabolism that were treated at 9 different children's hospitals in the US between 2000 and 2015.

RESULTS

Twenty-nine patients received hemodialysis (57%), 21 patients received continuous renal replacement therapy (41%), and 1 patient received peritoneal dialysis (2%). The median age at admission of both survivors (n = 33 [65%]) and nonsurvivors (n = 18) was 3 days. Peak ammonia and ammonia at admission were not significantly different between survivors and nonsurvivors. Hemodialysis, having more than 1 indication for RRT in addition to hyperammonemia, and complications during RRT were all risk factors for mortality. After accounting for multiple patient factors by multivariable analyses, hemodialysis was associated with a higher risk of death compared with continuous renal replacement therapy. When clinical factors including evidence of renal dysfunction, number of complications, concurrent extracorporeal membrane oxygenation, vasopressor requirement, and degree of hyperammonemia were held constant in a single Cox regression model, the hazard ratio for death with hemodialysis was 4.07 (95% CI 0.908-18.2, P value = .067). To help providers caring for neonates with hyperammonemia understand their patient's likelihood of survival, we created a predictive model with input variables known at the start of RRT.

CONCLUSIONS

Our large, multicenter retrospective review supports the use of continuous renal replacement therapy for neonatal hyperammonemia.

Unexplained Fatal Hyperammonemia in a Patient With New Diagnosis of Acute Monoblastic Leukemia

Idiopathic hyperammonemia is a serious condition that can arise after induction of chemotherapy and is characterized by plasma ammonia levels greater than two times the normal upper limit but within the context of normal liver function. While this dangerous complication usually appears several weeks after the start of chemotherapy, we report a fatal case of idiopathic hyperammonemia that was detected only nine days after induction chemotherapy in a 22-year-old man with no liver pathology or other risks for hyperammonemia. The patient’s initial emergent presentation was altered mental status. Laboratory workup showed acute monoblastic leukemia and radiological investigation showed cerebral hemorrhagic foci secondary to leukostasis. He received leukoreduction apheresis and he was started on induction chemotherapy with daunorubicin and cytarabine. On the ninth day of induction chemotherapy, it was noted that he developed worsening neurological findings. Investigations showed significant elevation in ammonia level and associated cerebral edema. Although hyperammonemia was mitigated, the patient’s cerebral status worsened and he died 15 days after initial presentation. This case shows that critical hyperammonemia can occur quickly after chemotherapy induction and that strategies for preventing a rise in plasma ammonia are necessary.

Towards an Algorithm-Based Tailored Treatment of Acute Neonatal Hyperammonemia

Acute neonatal hyperammonemia is associated with poor neurological outcomes and high mortality. We developed, based on kinetic modeling, a user-friendly and widely applicable algorithm to tailor the treatment of acute neonatal hyperammonemia. A single compartmental model was calibrated assuming a distribution volume equal to the patient's total body water (V), as calculated using Wells' formula, and dialyzer clearance as derived from the measured ammonia time-concentration curves during 11 dialysis sessions in four patients (3.2 ± 0.4 kg). Based on these kinetic simulations, dialysis protocols could be derived for clinical use with different body weights, start concentrations, dialysis machines/dialyzers and dialysis settings (e.g., blood flow QB). By a single measurement of ammonia concentration at the dialyzer inlet and outlet, dialyzer clearance (K) can be calculated as K = QB∙[(Cinlet - Coutlet)/Cinlet]. The time (T) needed to decrease the ammonia concentration from a predialysis start concentration Cstart to a desired target concentration Ctarget is then equal to T = (-V/K)∙LN(Ctarget/Cstart). By implementing these formulae in a simple spreadsheet, medical staff can draw an institution-specific flowchart for patient-tailored treatment of hyperammonemia.

Alkalemia and Hepatic Encephalopathy in a Chronic Dialysis Patient

Hepatic encephalopathy (HE) includes cognitive, psychiatric and neuromotor abnormalities observed from brain dysfunction secondary to liver disease and/or porto-systemic shunting. HE can have a wide range of clinical manifestations ranging from trivial lack of awareness, decreased attention span, personality changes to confusion, seizures, coma, and death. The onset of HE in cirrhosis is a poor prognostic factor. While HE has a complex pathogenesis which is not completely understood, hyperammonemia plays an important role in neurotoxicity and brain dysfunction. Alkalemia facilitates the conversion of NH₄⁺ to NH₃, which is free to cross the blood-brain barrier exacerbating HE. Prompt recognition and correction of underlying risk factors is central to the management of HE.

Successful management of a neonate with OTC deficiency presenting with hyperammonemia and severe cardiac dysfunction with extracorporeal membrane oxygenation support and continuous renal replacement therapy

Ornithine transcarbamylase (OTC) deficiency is an X-linked urea cycle disorder which-in severe form-results in rapid accumulation of ammonia and glutamine with subsequent irreversible brain injury. We present a case of severe left ventricular dysfunction with hyperammonemic crisis caused by OTC deficiency which was managed with veno-arterial extracorporeal membrane oxygenation support combined with continuous renal replacement therapy. Aggressive treatment led to normalization of ammonia and full left ventricular recovery.

A retrospective review of outcomes in the treatment of hyperammonemia with renal replacement therapy due to inborn errors of metabolism

BACKGROUND

Outcomes for severe hyperammonemia treated with renal replacement therapy (RRT) reported in the literature vary widely. This has created differing recommendations regarding when RRT is beneficial for hyperammonemic patients.

METHODS

To evaluate our institution's experience with RRT in pediatric patients with inborn errors of metabolism (IEMs) and potential prognostic indicators of a better or worse outcome, we performed a retrospective chart review of patients who received RRT for hyperammonemia. Our cohort included 19 patients with confirmed IEMs who received RRT between 2000 and 2017. Descriptive statistics are presented as medians with interquartile ranges with appropriate statistical testing assuming unequal variance.

RESULTS

There were 16 males (84%) and 3 females (16%) identified for inclusion in this study. There were 9 survivors (47%) and 10 non-survivors (53%). The average age of survivors was 67 months (age range from 3 days to 15.6 years). The average age of non-survivors was 1.8 months (age range from 2 days to 18.7 months). Peak ammonia, ammonia on admission, and at RRT initiation were higher in non-survivors compared with survivors. Higher ammonia levels and no change in ammonia between admission and RRT initiation were associated with an increased risk of mortality.

CONCLUSIONS

Hyperammonemia affects two distinct patient populations; neonates with markedly elevated ammonia levels on presentation and older children who often have established IEM diagnoses and require RRT after failing nitrogen-scavenging therapy. Our experience demonstrates no significant change in mortality associated with neonatal hyperammonemia, which remains high despite improvements in RRT and intensive care.

Continuous renal replacement therapy and transplant-free survival in acute liver failure: protocol for a systematic review and meta-analysis

BACKGROUND

Acute liver failure is a rare syndrome with significant morbidity and mortality, particularly in absence of transplantation as a rescue therapy. An important mechanism contributing to mortality is hyperammonemia which drives cerebral edema and raised intracranial pressure. Multiple therapies for managing hyperammonemia have been trialed. Continuous renal replacement therapy is effective in treating hyperammonemia in other disease states (notably inborn errors of metabolism). Its efficacy in acute liver failure has been suggested but further investigation is required to prove this. The objective of this systematic review will be to determine the efficacy of continuous renal replacement therapy in patients with acute liver failure and its effect on mortality and transplant-free survival.

METHODS

MEDLINE, EMBASE, Web of Science, and Cochrane Database will be searched. Identified studies will include all patients with acute liver failure in a critical care unit treated with continuous renal replacement therapy. Primary outcome will be effectiveness of ammonia clearance and mortality. Patients treated with any other modality of ammonia lowering therapy (such as plasma exchange or Molecular Adsorbent Recirculating System) will be excluded. Narrative synthesis of the identified studies will occur and if clinical homogeneity is identified, data will be pooled for meta-analysis using a DerSimonian-Laird random effects model.

DISCUSSION

We present a protocol for a systematic review seeking to establish a link between transplant-free survival in acute liver failure and the use of continuous renal replacement therapy. Given the anticipated paucity of literature on this subject, both narrative and quantitative syntheses are planned. SYSTEMATIC REVIEW REGISTRATION: (PROSPERO) CRD42019122520, registered April 16, 2019.

Consensus guidelines for management of hyperammonaemia in paediatric patients receiving continuous kidney replacement therapy

Hyperammonaemia in children can lead to grave consequences in the form of cerebral oedema, severe neurological impairment and even death. In infants and children, common causes of hyperammonaemia include urea cycle disorders or organic acidaemias. Few studies have assessed the role of extracorporeal therapies in the management of hyperammonaemia in neonates and children. Moreover, consensus guidelines are lacking for the use of non-kidney replacement therapy (NKRT) and kidney replacement therapies (KRTs, including peritoneal dialysis, continuous KRT, haemodialysis and hybrid therapy) to manage hyperammonaemia in neonates and children. Prompt treatment with KRT and/or NKRT, the choice of which depends on the ammonia concentrations and presenting symptoms of the patient, is crucial. This expert Consensus Statement presents recommendations for the management of hyperammonaemia requiring KRT in paediatric populations. Additional studies are required to strengthen these recommendations.

This expert Consensus Statement from the Pediatric Continuous Renal Replacement Therapy (PCRRT) workgroup presents recommendations for the management of hyperammonaemia requiring kidney replacement therapy in paediatric populations. Additional studies are needed to strengthen these recommendations, which will be reviewed every 2 years.

Continuous venovenous hemodiafiltration in the treatment of newborns with an inborn metabolic disease: a single center experience

Background/aim

Most inborn metabolic diseases are diagnosed during the neonatal period. The accumulation of toxic metabolites may cause acute metabolic crisis with long-term neurological dysfunction and death. Renal replacement therapy (RRT) modalities allow the efficient removal of toxic metabolites. In this study, we reviewed our experience with continuous venovenous hemodiafiltration (CVVHDF) as RRT for newborns with an inborn metabolic disease.

Materials and methods

Patients diagnosed with an inborn metabolic disease and who received CVVHDF treatment at our neonatal intensive care unit between January 2014 and December 2017 were included in this study. Their demographic and clinical data were collected, and the efficacy and safety of CVVHDF was evaluated.

Results

A total of nine continuous RRT (CRRT) sessions as CVVHDF were performed in eight newborns with a diagnosis of urea cycle defect (n = 5), maple syrup urine disease (n = 2), or methylmalonic acidemia (n = 1). The mean age at admission was 10 ± 8.6 days (range: 3–28 days). The mean plasma levels of ammonium were 1120 ± 512.6 mg/dL and 227.5 ± 141.6 mg/dL before and at the end of the treatment, respectively. Plasma levels of leucine were 2053.5 ± 1282 µmol/L and 473.5 ± 7.8 µmol/L before and at the end of the treatment, respectively. The CVVHDF duration was 32.3 ± 11.1 h (median: 37 h; range: 16–44 h), and the mean length of hospitalization was 14.6 ± 12.9 days. The mean duration of CVVHDF was 32.3 ± 11.1 h (range: 16–44 h). Circuit clotting was the most common observed complication (37.5%) and the survival rate was 50%. Among surviving patients, two developed severe and two developed mild mental and motor retardation.

Conclusion

CVVHDF is a CRRT modality that can be used to treat newborns with an inborn metabolic disease. Early diagnosis, commencement of specific medical therapy, diet, and extracorporeal support, if needed, are likely to result in improved short and long-term outcomes.

Basics of continuous renal replacement therapy in pediatrics

In the last three decades, significant advances have been made in the care of children requiring renal replacement therapy (RRT). The move from the use of only hemodialysis and peritoneal dialysis to continuous venovenous hemofiltration with or without dialysis (continuous renal replacement therapy, CRRT) has become a mainstay in many intensive care units. The move to CRRT is the result of greater clinical experience as well as advances in equipment, solutions, vascular access, and anticoagulation. CRRT is the mainstay of dialysis in pediatric intensive care unit (PICU) for critically ill children who often have hemodynamic compromise. The advantages of this modality include the ability to promote both solute and fluid clearance in a slow continuous manner. Though data exist suggesting that approximately 25% of children in any PICU may have some degree of renal insufficiency, the true need for RRT is approximately 4% of PICU admissions. This article will review the history as well as the progress being made in the provision of this care in children.

Continuous Renal Replacement Therapy with High Flow Rate Can Effectively, Safely, and Quickly Reduce Plasma Ammonia and Leucine Levels in Children

Introduction: Peritoneal dialysis and continuous renal replacement therapy (CRRT) are the most frequently used treatment modalities for acute kidney injury. CRRT is currently being used for the treatment of several non-renal indications, such as congenital metabolic diseases. CRRT can efficiently remove toxic metabolites and reverse the neurological symptoms quickly. However, there is not enough data for CRRT in children with metabolic diseases. Therefore, we aimed a retrospective study to describe the use of CRRT in metabolic diseases and its associated efficacy, complications, and outcomes. Materials and Methods: We performed a retrospective analysis of the records of all patients admitted in the pediatric intensive care unit (PICU) for CRRT treatment. Results: Between December 2014 and November 2018, 97 patients were eligible for the present study. The age distribution was between 2 days and 17 years, with a mean of 3.77 ± 4.71 years. There were 13 (36.1%) newborn with metabolic diseases. The patients were divided into two groups: CRRT for metabolic diseases and others. There was a significant relationship between the groups, including age (p ≤ 0.001), weight (p = 0.028), blood flow rate (p ≤ 0.001); dialysate rate (p ≤ 0.001), and replacement rate (p ≤ 0.001). The leucine reduction rate was 3.88 ± 3.65 (% per hour). The ammonia reduction rate was 4.94 ± 5.05 in the urea cycle disorder group and 5.02 ± 4.54 in the organic acidemia group. The overall survival rate was 88.9% in metabolic diseases with CRRT. Conclusion: In particularly hemodynamically unstable patients, CRRT can effectively and quickly reduce plasma ammonia and leucine.

Continuous Renal Replacement Therapy for Treatment of Severe Attacks of Inborn Errors of Metabolism

Severe metabolic crises in children with inborn errors of metabolism can result in mortality or severe morbidities where continuous renal replacement therapy (CRRT) can be lifesaving . Clinical data, the pediatric risk of mortality (PRISM) scores calculated in the first 24 hours, and pediatric logistic organ dysfunction (PELOD) scores calculated in the last 24 hours before CRRT, were studied . Overall, CRRT was successful in restoring metabolic balance in 72% of patients. PELOD scores before CRRT were lower in survivors ( p  = 0.02). Despite numerous comorbid factors, CRRT can be used effectively in management of metabolic crises. Early intervention with this therapy before occurrence of complications must be targeted.

Influence of implementing a protocol for an intravenously administered ammonia scavenger on the management of acute hyperammonemia in a pediatric intensive care unit

The purpose of the study was to evaluate the influence of establishing a protocol for the use of combined sodium benzoate and sodium phenylacetate (SBSP) (Ammonul®) to treat acute hyperammonemia. This was a retrospective, single-center study in a 24-bed medical and surgical pediatric intensive care unit (PICU) in a tertiary care teaching maternal-child hospital in Canada. Inclusion criteria were age < 18 years, PICU admission between 1 January 2000 and 30 June 2016, and SBSP treatment. An SBSP delivery protocol was implemented in our hospital on 30 August 2008 in order to improve management of acute hyperammonemia. Patients were assigned to one of the two groups, without or with protocol, depending on date of admission. SBSP was ordered 34 times during the study period, and 23 orders were considered for analysis (14 with and 9 without protocol). Patient characteristics were similar between groups. The median time from diagnosis to prescription was significantly shorter in the protocol group [40 min (21-82) vs 100 min (70-150), p = 0.03)] but the median time from diagnosis to administration of the treatment was equivalent [144 min (90-220) vs 195 (143-274), (p = 0.2)]. Other clinical outcomes did not differ. This study is the first to compare two SBSP delivery strategies in the treatment of acute hyperammonemia in this PICU setting. Implementation of a delivery protocol shortened the time from diagnosis of hyperammonemia to prescription of SBSP and helped us identify other parameters that can be improved to optimize treatment delivery.

Renal replacement therapy in neonates with an inborn error of metabolism

Hyperammonemia can be caused by several genetic inborn errors of metabolism including urea cycle defects, organic acidemias, fatty acid oxidation defects, and certain disorders of amino acid metabolism. High levels of ammonia are extremely neurotoxic, leading to astrocyte swelling, brain edema, coma, severe disability, and even death. Thus, emergency treatment for hyperammonemia must be initiated before a precise diagnosis is established. In neonates with hyperammonemia caused by an inborn error of metabolism, a few studies have suggested that peritoneal dialysis, intermittent hemodialysis, and continuous renal replacement therapy (RRT) are effective modalities for decreasing the plasma level of ammonia. In this review, we discuss the current literature related to the use of RRT for treating neonates with hyperammonemia caused by an inborn error of metabolism, including optimal prescriptions, prognosis, and outcomes. We also review the literature on new technologies and instrumentation for RRT in neonates

Peritoneal dialysis for the management of pediatric patients with acute kidney injury

Renal replacement therapy (RRT) is the most important supportive measure used in the management of acute kidney injury (AKI). Peritoneal dialysis (PD) is a safe, simple and inexpensive procedure and has been used in pediatric AKI patients, ranging from neonates to adolescents. It is the modality of choice for RRT in developing countries with cost constraints and limited resources. However, its use has declined with the availability of newer types of extracorporeal modalities for RRT in the developed world. Much controversy exists regarding the dosing and adequacy of PD in the management of AKI. Data in infants and children have shown that PD can provide adequate clearance, ultrafiltration and correction of metabolic abnormalities even in those who are critically ill. Although there are no prospective studies in children, data from retrospective studies reveal no differences in mortality rates between different modalities of RRT. In this review, we discuss the advantages and limitations of PD, indications for acute PD, strategies to improve the efficiency of acute PD and outcomes of PD in children with AKI.

The Role of RRT in Hyperammonemic Patients

Hyperammonemia is an important cause of cerebral edema in both adults with liver failure and children with inborn errors of metabolism. There are few studies that have analyzed the role of extracorporeal dialysis in reducing blood ammonia levels in the adult population. Furthermore, there are no firm guidelines about when to implement RRT, because many of the conditions that are characterized by hyperammonemia are extremely rare. In this review of existing literature on RRT, we present the body's own mechanisms for clearing ammonia as well as the dialytic properties of ammonia. We review the available literature on the use of continuous venovenous hemofiltration, peritoneal dialysis, and hemodialysis in neonates and adults with conditions characterized by hyperammonemia and discuss some of the controversies that exist over selecting one modality over another.

The complexity of dialytic therapy in hyperammonemic neonates

The utilization of renal replacement therapy (RRT) in the setting of hyperammonia is a rare and complicated occurrence. Data demonstrate that the quicker the ammonia level is normalized, the better the neurological outcome. The optimal form of RRT is often decided by local practice. The recent work by Picca and colleagues details a larger series of children who underwent RRT for hyperammonia and adds some credence to the use of peritoneal dialysis (PD) in this population. While these authors conclude that PD is not optimal, they do note that the use of PD may be an option when other forms of RRT are not available. The results reinforce the general maxim that you should continue to do that which you do well and often, which in this context refers to continuing to use your form of RRT until alternative modalities are available.

Treatment options for lactic acidosis and metabolic crisis in children with mitochondrial disease

The mitochondrial pyruvate oxidation route is a tightly regulated process, which is essential for aerobic cellular energy production. Disruption of this pathway may lead to severe neurometabolic disorders with onset in early childhood. A frequent finding in these patients is acute and chronic lactic acidemia, which is caused by increased conversion of pyruvate via the enzyme lactate dehydrogenase. Under stable clinical conditions, this process may remain well compensated and does not require specific therapy. However, especially in situations with altered energy demands, such as febrile infections or longer periods of fasting, children with mitochondrial disorders have a high risk of metabolic decompensation with exacerbation of hyperlactatemia and severe metabolic acidosis. Unfortunately, no controlled studies regarding therapy of this critical condition are available and clinical outcome is often unfavorable. Therefore, the aim of this review was to formulate expert-based suggestions for treatment of these patients, including dietary recommendations, buffering strategies and specific drug therapy. However, it is important to keep in mind that a specific therapy for the underlying metabolic cause in children with mitochondrial diseases is usually not available and symptomatic therapy especially of severe lactic acidosis has its ethical limitations.

Short-term survival of hyperammonemic neonates treated with dialysis

BACKGROUND

In severe neonatal hyperammonemia, extracorporeal dialysis (ECD) provides higher ammonium clearance than peritoneal dialysis (PD). However, there are limited outcome data in relation to dialysis modality.

METHODS

Data from infants with hyperammonemia secondary to inborn errors of metabolism (IEM) treated with dialysis were collected in six Italian centers and retrospectively analyzed.

RESULTS

Forty-five neonates born between 1990 and 2011 were enrolled in the study. Of these, 23 were treated with PD and 22 with ECD (14 with continuous venovenous hemodialysis [CVVHD], 5 with continuous arteriovenous hemodialysis [CAVHD], 3 with hemodialysis [HD]). Patients treated with PD experienced a shorter duration of predialysis coma, while those treated with HD had a shorter ammonium decay time compared with all the other patients (p < 0.05). No difference in ammonium reduction rate was observed between patients treated with PD, CAVHD or CVVHD. Carbamoyl phosphate synthetase deficiency (CPS) was significantly associated with increased risk of death (OR: 9.37 [1.52-57.6], p = 0.016). Predialysis ammonium levels were significantly associated with a composite end-point of death or neurological sequelae (adjusted OR: 1.13 [1.02-1.27] per 100 μmol/l, p = 0.026). No association was found between outcome and dialysis modality.

CONCLUSIONS

In this study, a delayed ECD treatment was not superior to PD in improving the short-term outcome of neonates with hyperammonemia secondary to IEM.

Hyperammonemia due to urea cycle disorders: a potentially fatal condition in the intensive care setting

Disorders of the urea cycle are secondary to a defect in the system that converts ammonia into urea, resulting in accumulation of ammonia and other products. This results in encephalopathy, coma, and death if not recognized and treated rapidly. Late-onset urea cycle disorders may be precipitated by acute disease and can be difficult to recognize because patients are already ill. Diagnosis of urea cycle disorders is based on clinical suspicion and determination of blood ammonia in suspected patients with neurological symptoms in the intensive care setting. Treatment is based on the removal of ammonia by dialysis or hemofiltration, reduction of the catabolic state, abolishment of nitrogen administration, and use of pharmacological nitrogen scavenging agents.

A biphasic dialytic strategy for the treatment of neonatal hyperammonemia

BACKGROUND

Neonates with inborn errors of metabolism (IEM) often develop hyperammonemia which, if not corrected quickly, may result in poor neurologic outcomes. As pharmacologic therapy cannot rapidly lower ammonia levels, dialysis is frequently required. Both hemodialysis (HD) and standard-dose continuous renal replacement therapy (CRRT) are effective; however, HD may be followed by post-dialytic ammonia rebound, and standard-dose CRRT may not effect a rapid enough decrease in ammonia levels.

CASE-DIAGNOSIS/TREATMENT

We present two cases of IEM-associated neonatal hyperammonemia in which we employed a biphasic, high-dose CRRT treatment strategy, initially using dialysate flow rates of 5,000 mL/h (approximately 40,000 mL/h/1.73 m(2)) in order to rapidly decrease ammonia levels, then decreasing the dialysate flow rates to 500 mL/h (approximately 4,000 mL/h/1.73 m(2)) in order to prevent ammonia rebound.

CONCLUSIONS

This biphasic dialytic treatment strategy for neonatal hyperammonemia effected rapid ammonia reduction without rebound and accomplished during a single dialysis run without equipment changes.

Efficacy and safety of intermittent hemodialysis in infants and young children with inborn errors of metabolism

BACKGROUND

Intermittent hemodialysis (IHD) is the most efficient form of renal replacement therapy (RRT) for removing toxic substances from patients' bodies. However, the efficacy and safety of IHD in infants and young children with inborn errors of metabolism are still not clear.

METHODS

This retrospective study included patients with urea cycle disorders, maple syrup urine disease, and methylmalonic acidemia who received IHD or non-IHD RRT at our hospital between 2001 and 2012 to remove ammonia, leucine, or methylmalonic acid. Both the efficacy and safety of the RRT were evaluated.

RESULTS

Thirty-five courses of RRT, including 25 courses of IHD and ten courses of non-IHD RRT, for 15 patients were included in the analysis. Before 2006, non-IHD RRT procedures, including peritoneal dialysis (PD) and continuous venous-venous hemofiltration (CVVH), were the most often used; from 2006 onwards IHD was used. There was one procedure-unrelated death. Catheter penetration occurred in one course of IHD. The efficacy data revealed that both the median duration of dialysis and the median 50 % toxin reduction time were shorter in IHD than in non-IHD RRT.

CONCLUSIONS

In infants and young children with inborn errors of metabolism, IHD is safe and more efficient than non-IHD RRT at removing toxins.

Feasibility of adjunct therapeutic hypothermia treatment for hyperammonemia and encephalopathy due to urea cycle disorders and organic acidemias

BACKGROUND

Children with urea cycle disorders (UCDs) or organic acidemias (OAs) and acute hyperammonemia and encephalopathy are at great risk for neurological injury, developmental delay, intellectual disability, and death. Nutritional support, intravenous alternative pathway therapy, and dialysis are used to treat severe hyperammonemia associated with UCDs and nutritional support and dialysis are used to treat severe hyperammonemia in OAs. Brain protective treatment while therapy is initiated may improve neurological and cognitive function for the lifetime of the child. Animal experiments and small clinical trials in hepatic encephalopathy caused by acute liver failure suggest that therapeutic hypothermia provides neuroprotection in hyperammonemia associated encephalopathy. We report results of an ongoing pilot study that assesses if whole body cooling during rescue treatment of neonates with acute hyperammonemia and encephalopathy is feasible and can be conducted safely.

METHODS

Adjunct whole body therapeutic hypothermia was conducted in addition to standard treatment in acutely encephalopathic, hyperammonemic neonates with UCDs and OAs requiring dialysis. Therapeutic hypothermia was initiated using cooling blankets as preparations for dialysis were underway. Similar to standard therapeutic hypothermia treatment for neonatal hypoxic ischemic encephalopathy, patients were maintained at 33.5°C±1°C for 72h, they were then slowly rewarmed by 0.5°C every 3h over 18h. In addition data of age-matched historic controls were collected for comparison.

RESULTS

Seven patients were cooled using the pilot study protocol and data of seven historic controls were reviewed. All seven patients survived the initial rescue and cooling treatment, 6 patients were discharged home 2-4weeks after hospitalization, five of them feeding orally. The main complication observed in a majority of patients was hypotension.

CONCLUSION

Adjunct therapeutic hypothermia for neonates with UCDs and OAs receiving standard treatment was feasible and could be conducted safely in pediatric and neonatal intensive care units experienced in the application of therapeutic hypothermia in critically ill neonates. However, including adjunct therapeutic hypothermia in the already involved treatment regimen of critically ill patients with hyperammonemia and encephalopathy adds to the complexity of care and should not be done unless it is proven efficacious in a randomized clinical trial.

High-dose continuous renal replacement therapy for neonatal hyperammonemia

BACKGROUND

Infants with hyperammonemia can present with nonspecific findings so ordering an ammonia level requires a high index of suspicion. Renal replacement therapy (RRT) should be considered for ammonia concentrations of >400 μmol/L since medical therapy will not rapidly clear ammonia. However, the optimal RRT prescription for neonatal hyperammonemia remains unknown. Hemodialysis and continuous renal replacement therapy (CRRT) are both effective, with differing risks and benefits.

CASE-DIAGNOSIS/TREATMENT

We present the cases of two neonates with hyperammonemia who were later diagnosed with ornithine transcarbamylase deficiency and received high-dose CRRT. Using dialysis/replacement flow rates of 8,000 mL/h/1.73 m(2) (1,000 mL/h or fourfold higher than the typical rate used for acute kidney injury) the ammonia decreased to <400 μmol/L within 3 h of initiating CRRT and to <100 μmol/L within 10 h.

CONCLUSIONS

We propose a CRRT treatment algorithm to rapidly decrease the ammonia level using collaboration between the emergency department and departments of genetics, critical care, surgery/interventional radiology, and nephrology.

Pediatric renal replacement therapy in the intensive care unit

Renal replacement therapy (RRT) is used in a wide variety of pediatric populations. In this article, we will review the advantages and disadvantages of the different RRT modalities and the technical aspects of providing pediatric RRT. In addition, we will review the use of RRT with extracorporeal membrane oxygenation, the use of continuous RRT in the critically ill child with acute kidney injury and fluid overload, and the use of RRT for the removal of toxins and treatment of inborn errors of metabolism.

Nonrenal indications for continuous renal replacement therapy: A report from the Prospective Pediatric Continuous Renal Replacement Therapy Registry Group

OBJECTIVE

Continuous renal replacement therapy is the most often implemented dialysis modality in the pediatric intensive care unit setting for patients with acute kidney injury. However, it also has a role in the management of patients with nonrenal indications such as clearance of drugs and intermediates of disordered cellular metabolism.

MEASUREMENTS AND METHODS

Using data from the multicenter Prospective Pediatric Continuous Renal Replacement Therapy Registry, we report a cohort of pediatric patients receiving continuous renal replacement therapy for nonrenal indications. Nonrenal indications were obtained from the combination of "other" category for continuous renal replacement therapy initiation and patient diagnosis (both primary and secondary). This cohort was further divided into three subgroups: inborn errors of metabolism, drug toxicity, and tumor lysis syndrome.

RESULTS

From 2000 to 2005, a total of 50 continuous renal replacement therapy events with nonrenal indications for therapy were included in the Prospective Pediatric Continuous Renal Replacement Therapy Registry. Indication-specific survival of the subgroups was 62% (inborn errors of metabolism), 82% (tumor lysis syndrome), and 95% (drug toxicity). The median small solute dose delivered among the subgroups ranged from 2125 to 8213 mL/1.73 m/hr, with 54%-59% receiving solely diffusion-based clearance as continuous venovenous hemodialysis. No association was established between survival and dose delivered, modality of continuous renal replacement therapy, or use of intermittent hemodialysis prior to continuous renal replacement therapy.

CONCLUSIONS

Pediatric patients requiring continuous renal replacement therapy for nonrenal indications are a distinct cohort within the population receiving renal replacement therapy with little published experience of outcomes for this group. Survival within this cohort varies by indication for continuous renal replacement therapy and is not associated with continuous renal replacement therapy modality. Additionally, survival is not associated with small solute doses delivered within a cohort receiving >2000 mL/1.73 m/hr. Our data suggest metabolic control is established rapidly in pediatric patients and that acute detoxification may be provided with continuous renal replacement therapy for both the initial and maintenance phases of treatment using either convection or diffusion at appropriate doses.

Newborn screening and renal disease: where we have been; where we are now; where we are going

Newborn screening (NBS) has rapidly changed since its origins in the 1960s. Beginning with a single condition, then a handful in the 1990 s, NBS has expanded in the past decade to allow the detection of many disorders of amino-acid, organic-acid, and fatty-acid metabolism. These conditions often present with recurrent acute attacks of metabolic acidosis, hypoglycemia, liver failure, and hyperammonemia that may be prevented with initiation of early treatment. Renal disease is an important component of these disorders and is a frequent source of morbidity. Hemodialysis is often required for hyperammonemia in the organic acidemias and urea-cycle disorders. Rhabdomyolysis with renal failure is a frequent complication in fatty-acid oxidation disorders. Newer screening methods are under investigation to detect lysosomal storage diseases, primary immunodeficiencies, and primary renal disorders. These advances will present many challenges to nephrologists and pediatricians with respect to closely monitoring and caring for children with such disorders.

Continuous renal replacement therapy in neonates weighing less than 3 kg

PURPOSE

Continuous renal replacement therapy (CRRT) is becoming the treatment of choice for supporting critically ill pediatric patients. However, a few studies present have reported CRRT use and outcome in neonates weighing less than 3 kg. The aim of this study is to describe the clinical application, outcome, and complications of CRRT in small neonates.

METHODS

A retrospective review was performed in 8 neonatal patients who underwent at least 24 hours of pumped venovenous CRRT at the Samsung Medical Center in Seoul, Korea, between March 2007 and July 2010. Data, including demographic characteristics, diagnosis, vital signs, medications, laboratory, and CRRT parameters were recorded.

RESULTS

The data of 8 patients were analyzed. At the initiation of CRRT, the median age was 5 days (corrected age, 38(+2) weeks to 23 days), and the median body weight was 2.73 kg (range, 2.60 to 2.98 kg). Sixty-two patient-days of therapy were reviewed; the median time for CRRT in each patient was 7.8 days (range, 1 to 37 days). Adverse events included electrolyte disturbances, catheter-related complications, and CRRT-related hypotension. The mean circuit functional survival was 13.9±8.6 hours. Overall, 4 patients (50%) survived; the other 4 patients, who developed multiorgan dysfunction syndrome, died.

CONCLUSION

The complications of CRRT in newborns are relatively high. However, the results of this study suggest that venovenous CRRT is feasible and effective in neonates weighing less than 3 kg under elaborate supportive care. Furthermore, for using potential benefit of CRRT in neonates, efforts are required for prolonging filter survival.

Threshold for toxicity from hyperammonemia in critically ill children

BACKGROUND & AIMS

Hyperammonemia results from reduction of hepatocyte function or enzyme of urea cycle deficiency. Hyperammonemia contributes to cerebral edema that may lead to cerebral herniation. The threshold of toxicity of ammonemia is unknown.

METHODS

We conducted a retrospective observational study in our pediatric intensive care unit. All children who developed hyperammonemia from January 2000 to April 2009 were included. Clinical and laboratory data at admission, specific treatments implemented, and ammonemias the first 7 days after inclusion were collected. The outcome assessed was 28 day mortality. Risk of mortality was estimated by a logistic regression model.

RESULTS

Ninety patients with liver failure (63.3%) and primary or secondary urea cycle defect (23.3%) were included. Patients with urea cycle defects were more likely to receive ammonia scavengers than patients with liver failure (47.6% versus 3.5%). The 28 day mortality rate was 31.1%. Risk of mortality increased according to the ammonemia within 48 h: odds ratio 1.5, 1.9, 3.3, 2.4 for ammonemia above 100, 150, 200, and 300 μmol/L, respectively. Peak ammonemia ≥200 μmol/L within the first 48 h was an independent risk factor for mortality, with greater risk found in liver failure than in urea cycle defect.

CONCLUSIONS

Our study identifies a threshold of exposure to ammonia (≥200 μmol/L) above which mortality increases significantly, especially in liver failure. Specific treatments of hyperammonemia are rarely used in liver failure when compared with urea cycle defect even though use of ammonia scavengers may help to decrease ammonemia.

Advances in pediatric renal replacement therapy

Advances in the understanding and clinical application of hemodialysis, peritoneal dialysis, and continuous renal replacement therapy have resulted in strategies designed to further improve their safety and efficacy. These advances have been particularly important to children, in whom a variety of clinical and technical issues must be taken into consideration for optimum dialysis across a broad spectrum of patient size and need. This manuscript reviews recent data pertaining to the use of renal replacement therapy, with an emphasis on those aspects of dialysis management that are especially pertinent to pediatric ESRD and acute kidney injury care.

Continuous hemofiltration in the control of neonatal hyperammonemia: a 10-year experience

In a 10-year review of the utilization of continuous veno-venous hemofiltration (CVVH) for the treatment of neonatal hyperammonemia, 14 patients were identified with hyperammonemia due to either a urea cycle defect or an organic acidemia. Intensive care survival was 64%. The pretreatment level of serum ammonia and the rapidity of ammonia clearance did not differ between survivors and non-survivors (p = 0.16 and p = 0.93, respectively). Likewise, the duration of CVVH therapy did not differ between survivors and non-survivors (p = 0.1). Indicators of pretreatment physiological stress showed either a correlation with non-survival [Pediatric Risk of Mortality (PRISM) score, p = 0.006, cardioactive drug requirement, p = 0.003], or demonstrated a trend to such a correlation (serum lactate, p = 0.06). Complications associated with the CVVH technique were infrequent. Hypotension was seen in seven patients, but in only one patient did it arise de novo following the initiation of CVVH. In conclusion, neither the severity of the hyperammonemic state nor the efficacy of ammonia removal correlated with patient outcome. The pre-CVVH PRISM score and requirement for cardio-active medication were significantly greater in those patients who did not survive their acute illness. The pre-CVVH physiological condition of the neonates in this cohort was the main determinant of outcome.

Rasburicase improves hyperuricemia in infants with acute kidney injury

Recent data suggest that elevated levels of uric acid (UA) might contribute to the progression of renal disease. Rasburicase, recombinant urate oxidase, is a highly safe and efficacious hypo-uricosuric agent for treatment of elevated UA levels from tumor lysis. We adopted the use of rasburicase for management of hyperuricemia in infants with acute kidney injury (AKI) and, herein, report our experience. We conducted a retrospective chart review of infants with hyperuricemia (UA > 8 mg/dl) secondary to AKI (serum creatinine > 1.5 mg/dl) treated with rasburicase. Seven infants (mean age 34 +/- 55 days, six male), with a mean weight of 3.2 +/- 1.2 kg, were identified. Rasburicase was administered intravenously as a single, onetime, bolus of 0.17 +/- 0.04 mg/kg body weight. Within 24 h, serum UA had decreased from 13.6 +/- 4.5 mg/dl to 0.9 +/- 0.6 mg/dl (P < 0.05), creatinine had decreased from 3.2 +/- 2.0 mg/dl to 2.0 +/- 1.2 mg/dl (P < 0.05), and urinary output had increased from 2.4 +/- 1.2 ml/kg per hour to 5.9 +/- 1.8 ml/kg per hour (P < 0.05). Continued improvements in UA, creatinine, and urinary output were observed in the week following administration of rasburicase, without rebound of the UA. We observed no treatment-related side effects. All patients demonstrated a normalization of uric acid level without need of renal replacement therapy. In conclusion, a single intravenously administered bolus of rasburicase appears to be a novel treatment for hyperuricemia in infants with AKI.

Nitrogen sparing therapy revisited 2009

Although the protocol that most experienced metabolic centers in the United States follow for treating acute hyperammonemia in urea cycle disorders (UCDs) is similar to that proposed by Brusilow and Batshaw in the early 1980s, over the years a steady evolution has taken place. Continued developments in intensive care, surgical and hemodialysis techniques, fluid and electrolyte management, cardiovascular support, and emergency transport have contributed to improved management of acute hyperammonemia. Compared to historical data, survival of urea cycle patients has also improved following treatment with alternative pathway therapy, in addition to appropriate supportive care, including the provision of adequate calories to prevent catabolism and promote anabolism and hemodialysis if needed. However, overall neurological outcomes have been suboptimal. There are currently a number of exciting prospective new therapies on the horizon, including novel medications or cell-based treatments. Nevertheless, the therapeutic expertise that is currently in place at centers specializing in management of metabolic emergencies already has the potential to improve survival and outcome in these children significantly. The early identification of UCD patients so that transport to a metabolic treatment center may be carried out without delay continues to be a major area of focus and challenge.

Hyperammonemic encephalopathy after induction chemotherapy for acute lymphoblastic leukemia

The syndrome of hyperammonemic encephalopathy occurs in patients who have received high-dose cytoreductive therapy for the treatment of hematologic malignancy. It is characterized by acute alteration in mental status and respiratory alkalosis associated with markedly elevated plasma ammonium levels in the absence of any identifiable cause and frequently results in cerebral edema, coma, and eventually death. Although the etiology of this syndrome is yet to be determined, it seems to be invariably multifactorial in nature. Optimal therapy remains elusive, and the critical step is increased awareness of the syndrome by measurement of plasma ammonia levels in patients with neurologic symptoms, leading to accurate diagnosis and the rapid implementation of therapy.

Continuous venovenous haemodialysis (CVVHD) and continuous peritoneal dialysis (CPD) in the acute management of 21 children with inborn errors of metabolism

BACKGROUND

Newborns with inborn errors of metabolism often present with hyperammonaemic coma, requiring prompt diagnosis and specific medical therapy, nutritional support and efficient toxin removal. Little information regarding the efficacy and safety of continuous venovenous haemodialysis (CVVHD) as an option for extracorporal ammonia detoxification in children is available.

METHODS

Twenty-one patients with hyperammonaemia [19 neonates (mean age 4.1 +/- 2.4 days) and two children 1 and 7 years of age, respectively] were admitted to our hospital for dialysis between 1996 and 2008. Seventeen children (15 neonates), received CVVHD. Four neonates received continuous peritoneal dialysis (CPD). All started medical treatment with sodium benzoate, l-arginine hydrochloride and carnitine as well as protein-restricted parenteral diets with high caloric intake before dialysis.

RESULTS

Plasma ammonia levels (range 464-7267 microg/dl before dialysis and 27-3317 microg/dl after dialysis) were significantly reduced by 50% within 4.7 +/- 2.5 h with CVVHD compared with 13.5 +/- 6.2 h with CPD (P < 0.0001). Plasma ammonia levels <200 microg/dl critical range were achieved within 22.4 +/- 18.1 h in CVVHD patients compared with 35.0 +/- 24.1 h with CPD. Depending on the weight and blood pressure stability of the patients, mean blood flow velocities of 9.8 +/- 3.4 ml/kg/min and mean dialysate flow rates of 3925 +/- 2398 ml/min/1.73 m(2) were employed. Blood and dialysate flows significantly correlated with ammonia clearance and decay of ammonia in vivo. Because of the severe underlying disease, 18% of CVVHD patients died compared with 50% undergoing CPD. In total, 82% of CVVHD patients survived the first 6 months after dialysis. Among these, 43% were without sequelae, 43% developed moderate mental retardation, and two (14%) developed severe mental retardation.

CONCLUSION

CVVHD effectively and quickly eliminates plasma ammonia. To optimize long-term mental outcome, rapid identification and appropriate treatment of the underlying disease as well as starting dialysis early are of enormous therapeutic value.

Dialysis and pediatric acute kidney injury: choice of renal support modality

Dialytic intervention for infants and children with acute kidney injury (AKI) can take many forms. Whether patients are treated by intermittent hemodialysis, peritoneal dialysis or continuous renal replacement therapy depends on specific patient characteristics. Modality choice is also determined by a variety of factors, including provider preference, available institutional resources, dialytic goals and the specific advantages or disadvantages of each modality. Our approach to AKI has benefited from the derivation and generally accepted defining criteria put forth by the Acute Dialysis Quality Initiative (ADQI) group. These are known as the risk, injury, failure, loss, and end-stage renal disease (RIFLE) criteria. A modified pediatrics RIFLE (pRIFLE) criteria has recently been validated. Common defining criteria will allow comparative investigation into therapeutic benefits of different dialytic interventions. While this is an extremely important development in our approach to AKI, several fundamental questions remain. Of these, arguably, the most important are "When and what type of dialytic modality should be used in the treatment of pediatric AKI?" This review will provide an overview of the limited data with the aim of providing objective guidelines regarding modality choice for pediatric AKI. Comparisons in terms of cost, availability, safety and target group will be reviewed.

Peritoneal dialysis in neonates with inborn errors of metabolism: is it really out of date?

Peritoneal and extracorporeal dialysis are used to treat newborns affected by inborn errors of metabolism to minimize the effects of the acute accumulation of neurotoxic metabolites that can produce irreversible and severe neurological damage and even death. In recent papers, extracorporeal dialysis has been described as more effective than peritoneal dialysis in improving the prognosis in newborns with inborn errors of metabolism and hyperammonemia. However, it appears that the outcome is primarily related to the duration of neonatal hyperammonemic coma. Here we report seven newborns with hyperammonemia caused by inborn errors of metabolism (five with organic acidemias, two with urea-cycle disorders). They received dietetic and pharmacological treatment as well as peritoneal dialysis. Four of the five patients with organic acidemia survived with and without mild neurological impairment (follow-up 3.5-10 years). One died from bacterial sepsis after peritoneal dialysis was discontinued and the peritoneal catheter was removed. One of the two patients affected by urea-cycle disorders, a boy, died during the neonatal period, and the other, a girl, died at the age of 13 months due to severe neurological damage. Our results demonstrate that peritoneal dialysis may still be an effective treatment for neonatal hyperammonemia caused by inborn errors of metabolism. Furthermore, peritoneal dialysis can be administered quickly and easily in all settings, clearly an advantage when fast intervention is so crucial.

Phenylacetate and benzoate clearance in a hyperammonemic infant on sequential hemodialysis and hemofiltration

An infant with a suspected inborn metabolism error was treated with a metabolic cocktail of intravenous sodium phenylacetate (NaPh) and sodium benzoate (NaBz) for hyperammonemia. Sequential hemodialysis (HD) then hemofiltration (HF) was performed due to hyperammonemia. Dialytic and convective clearance (K; ml/min) of ammonia, NaPh, and NaBz was measured. The K of ammonia was 57 and 37 for HD and HF, respectively. The K of NaBz was 37 and 12 for HD and HF, respectively. The K of NaPh was 38 and 14 ml/min for HD and HF, respectively. Despite high clearance of both NaPh and NaBz by HD and HF, the hyperammonemia was corrected.

Impact of inborn errors of metabolism on admission and mortality in a pediatric intensive care unit

The authors conducted a retrospective analysis of the patients admitted to a pediatric intensive care unit (PICU) during a five-year period, with specific focus on those with a suspected or confirmed diagnosis of inborn errors of metabolism (IEM), in order to ascertain the resources required to care for these patients. Medical records were reviewed for all admissions between January 1998 and December 2002 in a single metabolic referral center, and a subset of patients were identified with suspected IEM at admission or diagnosed IEM at hospital discharge. These patient charts were then further reviewed and the following information was extracted: IEM diagnosis, demographic data, biochemical characteristics at admission, need for mechanical ventilation, use of extracorporeal removal therapy, and outcome at PICU discharge. The study population comprised 70 patients (2.2% of all admissions during the study period) and included 33 neonates and 37 children aged >28 days. IEM diagnosis was known at the time of admission to the PICU in 9/33 of the neonates and 23/37 of the older children. Forty-three of the patients required invasive mechanical ventilation, while continuous extracorporeal removal therapy was used in 27 children. The median length of PICU stay was 3 days (range, 1 to 13 days) and 20 patients (28.6%) died. In conclusion, these observations show that inherited metabolic disease may be as frequent a primary diagnosis as septic shock in some PICUs. In neonates, these diseases are not usually diagnosed prior to PICU admission. Patients with IEM admitted to a PICU require aggressive support (including mechanical ventilation and extracorporeal removal therapies), and consume significant resources for relatively short PICU stays. These patients constitute a significant diagnostic and therapeutic challenge for pediatric intensivists.