Early changes in intracranial pressure during haemofiltration treatment in patients with grade 4 hepatic encephalopathy and acute oliguric renal failure

The Glymphatic System May Play a Vital Role in the Pathogenesis of Hepatic Encephalopathy: A Narrative Review

Hepatic encephalopathy (HE) is a neurological complication of liver disease resulting in cognitive, psychiatric, and motor symptoms. Although hyperammonemia is a key factor in the pathogenesis of HE, several other factors have recently been discovered. Among these, the impairment of a highly organized perivascular network known as the glymphatic pathway seems to be involved in the progression of some neurological complications due to the accumulation of misfolded proteins and waste substances in the brain interstitial fluids (ISF). The glymphatic system plays an important role in the clearance of brain metabolic derivatives and prevents aggregation of neurotoxic agents in the brain ISF. Impairment of it will result in aggravated accumulation of neurotoxic agents in the brain ISF. This could also be the case in patients with liver failure complicated by HE. Indeed, accumulation of some metabolic by-products and agents such as ammonia, glutamine, glutamate, and aromatic amino acids has been reported in the human brain ISF using microdialysis technique is attributed to worsening of HE and correlates with brain edema. Furthermore, it has been reported that the glymphatic system is impaired in the olfactory bulb, prefrontal cortex, and hippocampus in an experimental model of HE. In this review, we discuss different factors that may affect the function of the glymphatic pathways and how these changes may be involved in HE.

Kidney Replacement Therapy in Patients with Acute Liver Failure and End-Stage Cirrhosis Awaiting Liver Transplantation

Providing dialysis to patients with liver failure is challenging because of their tenuous hemodynamics and refractory ascites. With better machinery and increased availability, continuous kidney replacement therapy has been successfully delivered to acutely ill patients in liver failure over the past few decades. Intermittent hemodialysis continues to remain the modality of choice outside the intensive care unit and on occasion needs to be complemented with paracentesis. Peritoneal dialysis has not been widely used, but recent literature shows promising outcomes barring for publication bias. Albumin dialysis could be a lifesaving procedure for a carefully selected subgroup of patients with liver failure.

Organizational and financial aspects of a continuous renal replacement therapy program

Critically ill patients who develop severe acute kidney injury in the intensive care unit often require treatment with renal replacement therapies (RRTs). This complication is associated with severe morbidity and mortality and high costs, both during hospitalization and postdischarge. This article discusses the operational requirements to develop and conduct a RRT program, as well as the financial implications of this complex form of patient care. The management of these programs must occur in a context where a clear organizational and educational framework and a multidisciplinary team ensures safety, effectiveness, cost-control, and a clear quality control framework.

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.

Chronic Kidney Disease and Cerebrovascular Disease: Consensus and Guidance From a KDIGO Controversies Conference

The global health burden of chronic kidney disease is rapidly rising, and chronic kidney disease is an important risk factor for cerebrovascular disease. Proposed underlying mechanisms for this relationship include shared traditional risk factors such as hypertension and diabetes, uremia-related nontraditional risk factors, such as oxidative stress and abnormal calcium-phosphorus metabolism, and dialysis-specific factors such as cerebral hypoperfusion and changes in cardiac structure. Chronic kidney disease frequently complicates routine stroke risk prediction, diagnosis, management, and prevention. It is also associated with worse stroke severity, outcomes and a high burden of silent cerebrovascular disease, and vascular cognitive impairment. Here, we present a summary of the epidemiology, pathophysiology, diagnosis, and treatment of cerebrovascular disease in chronic kidney disease from the Kidney Disease: Improving Global Outcomes Controversies Conference on central and peripheral arterial disease with a focus on knowledge gaps, areas of controversy, and priorities for research.

Brain Herniation and Intracranial Hypertension

This article introduces the basic concepts of intracranial physiology and pressure dynamics. It also includes discussion of signs and symptoms and examination and radiographic findings of patients with acute cerebral herniation as a result of increased as well as decreased intracranial pressure. Current best practices regarding medical and surgical treatments and approaches to management of intracranial hypertension as well as future directions are reviewed. Lastly, there is discussion of some of the implications of critical medical illness (sepsis, liver failure, and renal failure) and treatments thereof on causation or worsening of cerebral edema, intracranial hypertension, and cerebral herniation.

A case report with a literature review: cerebral meningioma diagnosed by convulsion and consciousness disorder on initiating hemodialysis

Background

Neurological symptoms sometimes occur in hemodialysis patients, with causes including cerebral infarction, cerebral hemorrhaging, meningitis, and encephalitis. Dialysis disequilibrium syndrome (DDS) is widely known as a complication of hemodialysis and is typically encountered in severe uremic patients newly started on hemodialysis. The pathogenesis of DDS is thought to be brain edema that manifests as neurological symptoms, including headache, nausea, confusion, seizures, and coma. However, the relationship between brain tumors and neurological manifestations during hemodialysis is poorly understood.

Case presentation

The patient was a 55-year-old man with severe renal dysfunction and uremia symptoms. Blood chemistry showed severe azotemia and acidosis. The patient was placed on short-duration hemodialysis (2 h) with a relatively small surface area, low blood flow (100 mL/min), and intradialytic glycerol infusion to prevent DDS. However, after his first hemodialysis treatment, he complained of disturbed consciousness. We diagnosed his neurological condition as DDS and observed the progress carefully. The next morning, his symptoms had completely resolved, so the patient was started on his second hemodialysis session with the same conditions. However, 2 h after starting the second hemodialysis session, he suffered convulsions accompanied by impaired consciousness. Brain computed tomography (CT) revealed a convexity meningioma and cerebral edema with a midline shift. Before starting the hemodialysis, he had shown no history of seizures, morning headache, or other neurological symptoms. In this case, meningioma was diagnosed based on an increase in the intracranial pressure which occurred after the initiation of hemodialysis.

Conclusion

We report this suggestive case to prompt physicians to consider the potential effect of hemodialysis introduction on the brain pressure.

A quarter pound of acetaminophen with propylene glycol on the side: A case report

Particularly large acetaminophen overdoses, termed massive, create a therapeutic challenge given the standardized, N-acetylcysteine-based treatment. One consideration in addition to N-acetylcysteine is the initiation of hemodialysis due to the dialyzable nature of acetaminophen, though encumbered by the concurrent removal of the antidote, N-acetylcysteine. Such cases of large acetaminophen overdose, along with possible concomitant ingestions of other drugs or inactive ingredients, can be complicated by challenging-to-interpret clinical signs and laboratory findings. We describe a case of a 46-year-old man for whom we were consulted regarding consideration of dialysis treatment 7 hours after ingestion of 125 g of acetaminophen. The patient developed multiple early signs and laboratory findings consistent with a significant acetaminophen overdose. He also developed a rarely described, likely acetaminophen-interference-induced laboratory abnormality. Finally, he possibly had toxicity from an “inactive” ingredient. He was treated with a single session of prolonged hemodialysis (9.5 hours) and increased dosing of N-acetylcysteine with a positive outcome. Herein, we discuss the decision making and interpretation of clinical data pertaining to dialysis treatment and other therapies after a massive acetaminophen overdose.

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.

Pathogenesis of cerebral edema in patients with acute renal and liver failure and the role of the nephrologist in the management

PURPOSE OF REVIEW

Acute liver failure (ALF) is a severe and complex illness and one of the most daunting conditions managed in the ICU. Because the renal care is intertwined with multiple disciplines, the aim of this review is to examine the multifactorial pathogenesis of cerebral edema in ALF, covering basic established facts as well as recent advances in our understanding of this condition.

RECENT FINDINGS

Acetaminophen remains the most common cause of ALF in the United States and many European countries. The incidence of cerebral edema continues to decline owing to earlier detection and improved management. The pathogenesis of cerebral edema has shifted from a unifactorial hypothesis involving the failed liver to a multifactorial cause. Recent evidence focuses on the role of liver-induced systemic inflammation and its implication in increasing the permeability of the blood-brain barrier. The role of brain aquaporin-4 in mediating water entry into the brain is further clarified. Controversial data regarding the effect of acute kidney injury on the brain emerged. Hyponatremia has been shown to worsen the outcome in acute-on-chronic liver failure patients thus validating findings in animal models. New evidence shed the light on the changes in serum osmolality and potential tissue hypoxia during continuous renal replacement therapy and points to the risks associated with such therapy.

SUMMARY

ALF is a severe systemic illness that is potentially reversible. Understanding the interaction between the multiple failed organs will help the nephrologist provide well tolerated and efficient care.

Clinical Outcomes of Peritoneal Dialysis in End-Stage Renal Disease Patients with Liver Cirrhosis: A Propensity Score Matching Study

Background

Clinical results of long-term peritoneal dialysis (PD) therapy in patients with liver cirrhosis (LC) and end-stage renal disease (ESRD) are controversial. This study evaluated the clinical outcomes of LC patients undergoing PD.

Methods

Clinical records were retrospectively collected from a single center between January 2007 and December 2014. An analysis of PD patients with LC and without liver disease was performed using propensity score matching. We further restricted matching by age, gender, and the presence of diabetes mellitus. Two cohorts of 33 patients each were selected. Early technical complications were defined as the presence of catheter-related complications, including malposition, leakage, omental wrapping, obstruction, and requiring a transfer to hemodialysis (HD) within 6 months of initiating PD.

Results

Mean PD duration was lower in LC patients (57.2 ± 46.1 months) than in controls (85.8 ± 64.2 months). Blood urea nitrogen, creatinine, and albumin levels were significantly lower in LC patients than in the control group. Cystatin C and cystatin C-based glomerular filtration rates were not significantly different in the LC group compared with those in the controls. We found that the risks for early technical complications, peritonitis, and long-term PD and patient survival were not higher in patients with LC than in those without LC. Ascites were easily controlled, and hepatic encephalopathy did not affect PD maintenance in LC patients.

Conclusions

The clinical outcomes, including technical complications, peritonitis, and patients’ survival, suggest that PD can be used as a renal replacement therapy in ESRD patients with LC.

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.

Spontaneous Extradural Hemorrhage in a Patient with Chronic Kidney Disease: A Case Report and Review of Literature

BACKGROUND

Spontaneous extradural hemorrhage is a rare entity. It is usually reported in association with locoregional disease, which is often infective, inflammatory, and hematologic. Chronic kidney disease with hemodialysis is one of the most infrequent causes. The exact association or pathogenesis remains elusive, although possible mechanisms have been suggested. The presentation, associated comorbid conditions, and management vary among the reported cases.

CASE DESCRIPTION

A 39-year-old man with hypertension, well controlled with medications, and chronic kidney disease was on maintenance hemodialysis. He later underwent Tenckhoff catheter insertion for peritoneal dialysis; 2 weeks later, when peritoneal dialysis was started, he developed breathlessness. The Tenckhoff catheter was removed. However, the patient developed ascitic leak from the surgical site, which was repaired under general anesthesia. In the immediate postoperative period, he developed sudden, severe headache and was found to have bifrontal extradural hemorrhage. He underwent prompt drainage of the hematoma and was discharged on the fifth postoperative day in stable condition.

CONCLUSIONS

We report a rare case of spontaneous bilateral frontal extradural hemorrhage in the immediate postoperative period in a patient on hemodialysis. In addition, we review the existing literature on the topic.

Spontaneous nontraumatic subarachnoid hemorrhage without cerebrovascular malformations in a maintenance hemodialysis patient

Nontraumatic subarachnoid hemorrhage (SAH) in a dialysis patient is an uncommon occurrence and is often associated with high mortality. We report for the first time in India, a case of spontaneous nontraumatic, nonaneurysmal SAH without any cerebrovascular malformation in a maintenance hemodialysis patient, following a session of hemodialysis. The dialysis prescription needs to be modified in these patients, in order to prevent worsening of cerebral edema and progression of hemorrhage. Where available, continuous forms of renal replacement therapies, with regional anticoagulation seem to be the best option for such patients, till neurologic stabilization is achieved.

What a Nephrologist Needs to Know About Acute Liver Failure

Although relatively rare in the United States, acute liver failure (ALF) is associated with very high rates of morbidity and mortality. A leading cause of morbidity and mortality is cerebral edema and intracranial hypertension. Hypothermia, osmotic diuretics, and hyperosmolar therapy are commonly used to manage these complications; however, when these are ineffective, renal replacement therapy may be needed for volume management. Acute kidney injury is a common complication of ALF and may arise from a number of etiologies, including hepatorenal syndrome and acute tubular necrosis. Acute kidney injury is most common in patients who develop ALF because of acetaminophen toxicity or ischemia. With regard to renal replacement therapy, we will review specific considerations relevant to the management of the patient with ALF.

Use of High-Flow Continuous Renal Replacement Therapy with Citrate Anticoagulation to Control Intracranial Pressure by Maintaining Hypernatremia in a Patient with Acute Brain Injury and Renal Failure

Traumatic brain injury and intracranial hypertension often require treatment to optimize patient outcome. There are a variety of complex medical conditions that can preclude standard approaches to the treatment of intracranial hypertension. We describe a case where a novel approach using continuous dialysis with trisodium citrate was used to optimize the outcome of a young male with acute renal failure and acute respiratory distress syndrome in the setting of acute traumatic brain injury.

Renal replacement therapy in acute kidney injury: controversy and consensus

Renal replacement therapies (RRTs) represent a cornerstone in the management of severe acute kidney injury. This area of intensive care and nephrology has undergone significant improvement and evolution in recent years. Continuous RRTs have been a major focus of new technological and treatment strategies. RRT is being used increasingly in the intensive care unit, not only for renal indications but also for other organ-supportive strategies. Several aspects related to RRT are now well established, but others remain controversial. In this review, we review the available RRT modalities, covering technical and clinical aspects. We discuss several controversial issues, provide some practical recommendations, and where possible suggest a research agenda for the future.

[New KDIGO guidelines on acute kidney injury. Practical recommendations]

The incidence of acute kidney injury (AKI) in critically ill patients is very high and is associated with an increased morbidity and mortality. In 2012 the Kidney Disease: Improving Global Outcome (KDIGO) guidelines were published in which evidence-based practical recommendations are given for the evaluation and management of patients with AKI. The first section of the KDIGO guidelines deals with the unification of earlier consensus definitions and staging criteria for AKI. The subsequent sections of the guidelines cover the prevention and treatment of AKI as well as the management of renal replacement therapy (RRT) in patients with AKI. In each section the existing evidence is discussed and a specific treatment recommendation is given. The guidelines appreciates that there is insufficient evidence for many of the recommendations. As a specific pharmacological therapy is missing, an early diagnosis, aggressive hemodynamic optimization, tight volume control, and avoidance of nephrotoxic drugs are the only interventions to prevent AKI. If renal replacement therapy is required different modalities are available to provide an effective therapy with a low rate of adverse effects.

Randomized trial of frequent low-efficiency and short hemodialysis/hemofiltration in hemodialysis patients with acute brain injury

PURPOSE

The aim of the study was to compare effects of frequent low-efficiency and short hemodialysis (FLESHD) and frequent low-efficiency and short hemofiltration (FLESHF) in hemodialysis (HD) patients with acute brain injury (ABI).


METHODS

We randomly divided 13 HD patients with ABI into FLESHD (n = 6) or FLESHF (n = 7) groups. Conditions for the first to third sessions were as follows.

FLESHD

intravenous administration of glycerol 400 ml/session, blood flow rate (QB) 100 ml/min, dialysate flow rate 300 ml/min, and treatment duration 2 h (HD-1).

FLESHF

intravenous administration of glycerol 400 ml/session, QB 150 ml/min, substitution flow rate 10 l/session, and treatment duration 4 h (HF-1). After the fourth session, we gradually changed the conditions and stopped glycerol administration (HD-2 and HF-2).


RESULTS

There were no significant differences in survival rate, consciousness level, or adverse effects during hospitalization in either group. In mixed model analysis, the level of HCO3- post FLESHF was significantly (p<0.0001) increased compared with the level post FLESHD. However, no significant differences were seen in the levels of osmolality, in blood pressure before and after either dialysis method, or in the level of HCO3- pre dialysis. The variation in the relative ratio of BUN before FLESHF was significantly higher (p<0.05) than the relative ratio before FLESHD in the sixth session. In the FLESHD groups, serum sodium was higher and serum potassium was lower than in the FLESHF groups.


CONCLUSIONS

FLESHD with glycerol under these conditions may be a better therapeutic option for managing patients with ABI, although the short-term survival rate is similar.

Fulminant viral hepatitis

Acute liver failure (ALF) is a condition wherein the previously healthy liver rapidly deteriorates, resulting in jaundice, encephalopathy, and coagulopathy. There are approximately 2000 cases per year of ALF in the United States. Viral causes (fulminant viral hepatitis [FVH]) are the predominant cause of ALF in developing countries. Given the ease of spread of viral hepatitis and the high morbidity and mortality associated with ALF, a systematic approach to the diagnosis and treatment of FVH is required. In this review, the authors describe the viral causes of ALF and review the intensive care unit management of patients with FVH.

Renal replacement therapy in acute kidney injury

Although the use of renal replacement therapy (RRT) to support critically ill patients with acute kidney injury (AKI) has become routine, many of the fundamental questions regarding optimal management of RRT remain. This review summarizes current evidence regarding the timing of initiation of RRT, the selection of the specific modality of RRT, and prescription of the intensity of therapy. Although absolute indications for initiating RRT-such as hyperkalemia and overt uremic symptoms-are well recognized, the optimal timing of therapy in patients without these indications continues to be a subject of debate. There does not appear to be a difference in either mortality or recovery of kidney function associated with the various modalities of RRT. Finally, providing higher doses of RRT is not associated with improved clinical outcomes.

Structured approach to treat patients with acute liver failure: A hepatic emergency

Acute liver failure (ALF) is a condition of acute hepatic emergency where rapid deterioration of hepatocyte function leads to hepatic encephalopathy, coagulopathy, cerebral edema (CE), infection and multi-organ dysfunction syndrome resulting in a high mortality rate. Urgent liver transplantation is the standard of care for most of these patients in Western countries. However, in India, access to liver transplantation is severely limited and, hence, the management is largely based on intensive medical care. With earlier recognition of disease, better understanding of pathophysiology and improved intensive care, ALF patients have shown a significant improvement in spontaneous survival. An evidence base for practice for supportive care is still lacking; however, intensive organ support as well as control of infection and CE are likely to be key to the successful outcome in this acute and potentially reversible condition without any sequel. A structured approach to decision making about intensive care is important in each case. Unlike in Western countries where acetamenophen is the most common cause of ALF, the role of a specific agent, such as N-acetylcysteine, is limited in India. Ammonia-lowering therapy is still in an evolving phase. The current review highlights the important medical management issues in patients with ALF in general as well as the management of major complications associated with ALF. We performed a MEDLINE search using combinations of the key words such as acute liver failure, intensive treatment of acute liver failure and fulminant hepatic failure. We reviewed the relevant publications with regard to intensive care of patients with ALF.

Management of acute kidney injury in neurotrauma

Fortunately, the incidence of acute kidney injury (AKI) in neurotrauma is low and decreasing. Whereas the majority of AKI occurs in older patients with pre-existing chronic kidney disease, neurotrauma typically occurs in children and young adults with normal renal function. The development of outreach trauma teams has improved initial resuscitation, reducing both volume responsive and volume unresponsive cases of AKI. Most cases occur in the setting of multiple organ trauma with muscle injury, or patients who subsequently develop multiple organ failure. Once AKI has developed and renal replacement therapy is required, continuous modalities of renal replacement therapy offer an advantage to the patient with compromised cerebral perfusion and intracranial hypertension, by reducing the rate of change in serum urea, compared with standard intermittent therapies of hemodialysis and hemofiltration, thus minimizing abrupt changes in serum osmolality. Continuous hemodialysis and hemofiltration are better suited to maintain a normal or high serum sodium and thermal losses through the extracorporeal circuit, than peritoneal dialysis. Dialyzers should preferably be minimally bioincompatible and of a small surface area. In patients at risk of intracranial hemorrhage and those with invasive intracranial monitoring, systemic anticoagulants should either be avoided or regional anticoagulants should be used.

Continuous renal replacement therapy for refractory intracranial hypertension

INTRODUCTION

Little is known about the effects of hemodialysis on the injured brain, however; concern exists over the use of intermittent hemodialysis in patients with acute brain injury (ABI) due to its hemodynamic effects and increased intracranial pressure (ICP) associated with therapy. Continuous renal replacement therapy (CRRT) has become the preferred method of renal support in these patients though there is limited data to support its safety. Furthermore, exacerbations of cerebral edema have been reported. CRRT is an option for the treatment of hypervolemia and in theory may improve intracranial compliance. We report the case of a poly-trauma patient with severe traumatic brain injury (TBI) in which CRRT was implemented solely for refractory intracranial hypertension.

METHODS

A 28-year-old male was involved in a high-speed motor vehicle collision suffering a severe TBI and polytrauma. He required significant volume resuscitation. Intensive care unit course was complicated by shock, acute respiratory distress syndrome, ventilator associated pneumonia, and development of intracranial hypertension (IH). Data were collected by retrospective chart review.

RESULTS

Continuous hemofiltration was initiated for IH refractory to medical therapy. Within hours of initiation increase, ICP improved and normalized. Hemofiltration was safely discontinued after 48 h. Modified Rankin Score was 2 at 90 days.

CONCLUSION

Though unproven, CRRT may be beneficial in patients with IH due to gentle removal of fluid, solutes, and inflammatory cytokines. Given the limited data on safety of CRRT in patients with ABI, we encourage further reports.

Continuous renal replacement therapies in patients with liver disease

Patients with acute and chronic liver disease are prone to hypotension, and mortality increases when acute kidney injury supervenes. Hypotension during renal replacement therapy compromises cerebral perfusion, which can exacerbate cerebral edema in cases of fulminant hepatic failure and those with encephalopathy due to chronic liver failure. As such, any renal replacement therapy utilized should have minimal adverse effects on cardiovascular and cerebrovascular stability. Continuous modes of renal replacement therapy have been shown to cause less cardiovascular and cerebrovascular instability compared to other modalities, and as such are the treatments of choice for this group of critically ill patients.

Hemodialysis for hyperammonemia associated with ornithine transcarbamylase deficiency

Acute hyperammonemia is a medical emergency requiring rapid recognition and treatment to prevent devastating neurologic sequelae. Its varying etiologies include primary hepatic failure, drug toxicity, infection, and inherited disorders of metabolism. Ornithine transcarbamylase (OTC) deficiency is the most common inherited urea cycle disorder and can result in hyperammonemic encephalopathy and coma, often presenting in the newborn or early childhood. Partial deficiencies of the enzyme can present later in adulthood with protean neuropsychiatric signs and symptoms. Early recognition and management of metabolic encephalopathy is crucial to avoid neurologic damage, and may require hemodialysis for rapid removal of ammonia, with adjunctive medications and dietary modifications to decrease endogenous nitrogen production and activate alternate pathways of nitrogen excretion. We present the case of an adult patient with partial OTC deficiency who presented with encephalopathy, coma, and seizures, accompanied by hyperammonemia and treated acutely with hemodialysis.

Intensive care of patients with acute liver failure: recommendations of the U.S. Acute Liver Failure Study Group

OBJECTIVE

To provide a uniform platform from which to study acute liver failure, the U.S. Acute Liver Failure Study Group has sought to standardize the management of patients with acute liver failure within participating centers.

METHODS

In areas where consensus could not be reached because of divergent practices and a paucity of studies in acute liver failure patients, additional information was gleaned from the intensive care literature and literature on the management of intracranial hypertension in non-acute liver failure patients. Experts in diverse fields were included in the development of a standard study-wide management protocol.

MEASUREMENTS AND MAIN RESULTS

Intracranial pressure monitoring is recommended in patients with advanced hepatic encephalopathy who are awaiting orthotopic liver transplantation. At an intracranial pressure of > or =25 mm Hg, osmotic therapy should be instituted with intravenous mannitol boluses. Patients with acute liver failure should be maintained in a mildly hyperosmotic state to minimize cerebral edema. Accordingly, serum sodium should be maintained at least within high normal limits, but hypertonic saline administered to 145-155 mmol/L may be considered in patients with intracranial hypertension refractory to mannitol. Data are insufficient to recommend further therapy in patients who fail osmotherapy, although the induction of moderate hypothermia appears to be promising as a bridge to orthotopic liver transplantation. Empirical broad-spectrum antibiotics should be administered to any patient with acute liver failure who develops signs of the systemic inflammatory response syndrome, or unexplained progression to higher grades of encephalopathy. Other recommendations encompassing specific hematologic, renal, pulmonary, and endocrine complications of acute liver failure patients are provided, including their management during and after orthotopic liver transplantation.

CONCLUSIONS

The present consensus details the intensive care management of patients with acute liver failure. Such guidelines may be useful not only for the management of individual patients with acute liver failure, but also to improve the uniformity of practices across academic centers for the purpose of collaborative studies.

Reviews: The Current State of Nonuremic Applications for Extracorporeal Blood Purification

Despite the commonly accepted indications for hemodialysis and extracorporeal depuritive techniques, some clinicians have come to rely on blood purification for clinical states where the targeted substance for removal differs from uremic waste products. Over the last decade, a number of studies have emerged to help define the application of extracorporeal blood purification (ECBP) to these "nonuremic" indications. This review describes the application of extracorporeal blood purification in clinical states including sepsis, rhabdomyolysis, congestive heart failure, hepatic failure, tumor lysis syndrome, adult respiratory distress syndrome, intravenous contrast exposure, and lactic acidosis. Additional comments are provided to review existing literature on thermoregulation and osmoregulation, including acute brain injury.

[Severe Reye syndrome: report of 14 cases managed in a pediatric intensive care unit over 11 years]

Idiopathic Reye syndrome is a rare disease revealed by unexplained encephalopathy and microvesicular liver steatosis. Some clinical and epidemiological studies mainly performed in English speaking countries questioned the reality of Reye syndrome because numerous know inherited metabolic diseases, and some of them unrecognized, could mimick this disorder. We focused in our study on severe forms of Reye syndrome admitted to a pediatric intensive care unit.

METHODS

Retrospective study over the last eleven years (1991-2001) included all the pediatric patients admitted to our tertiary referral center with the classical American Reye syndrome criteria (e.g. CDC). Extensive metabolic screening was performed in all cases, except for the ultimately dead patients.

RESULT

Fourteen patients (mean age 52 months) were included. Fever always occurred before their admission and aspirin (n = 12) or acetaminophen (n = 7) was prescribed. Median Glasgow scale was 7 on admission. Mean amoniac plasma level was 320 mumol/L and alanine-aminotransferase peak plasma level 1475 +/- 1387 IU/L. Mechanical ventilation was started in ten children and six of them underwent continuous venovenous hemofiltration. Three patients ultimately died and 11 survived with a mean five years follow-up without relapses or neurological impairment. Any of them demonstrated inherited metabolic disease except for one infant with hereditary fructose intolerance.

CONCLUSION

Unlike widespread opinion, severe Reye syndrome without identified metabolic disorders seems to not disappear in our country. Reye syndrome remains a potentially life threatening disease and raises for aggressive treatment of brain edema. If aspirin and Reye syndrome association are not formally documented in France, cautiousness must be kept in mind and all the aspirin adverse effects notifications should be addressed to the public drugs survey network.

Renal replacement therapy in the patient with acute brain injury

The patient with an acute brain injury requiring renal replacement therapy presents a major problem in that conventional intermittent hemodialysis may exacerbate the injury by compromising cerebral perfusion pressure, either after a reduction in cerebral perfusion or because of increased cerebral edema. Compared with standard intermittent hemodialysis, the continuous forms of renal replacement therapy (CRRT) provide an effective therapy in terms of solute clearance, coupled with improved cardiovascular and intracranial stability. The disadvantage of CRRT is that anticoagulation may be required, and anticoagulants with systemic effects may provoke intracerebral hemorrhage, either at the site of damage or around the intracranial pressure monitoring device. Although peritoneal dialysis does not require anticoagulation, the clearances achieved are often less than those of CRRT, and sudden changes in intraperitoneal volume may provoke cardiovascular and thus intracranial instability.

Polyacrylonitrile membrane interposition between a xenograft and a patient in fulminant liver failure: the concept of xenohemodiafiltration in clinical practice

Fulminant hepatic failure is an important cause of morbidity and mortality in intensive care units. Conventional therapies are not sufficiently effective. Liver transplantation may be life saving, but a "bridge therapy" is needed until transplantation is performed. Hepatic extracorporeal xenohemodiafiltration (XHDF) is aimed at the transitory support of a patient with fulminant hepatic failure. The first clinical case of XHDF is presented. The system consisted of cross-circulation between a porcine liver and a patient with fulminant liver failure through a polyacrylonitrile membrane. The procedure lasted for 5 hours and produced hemodynamic, biochemical, and metabolic improvements. Intracranial pressure decreased from 34 to 5 cm H2O, serum ammonia fell from 673 to 370 ng/dl, lactic acid from 11 to 5.3 mmol/L, and bilirubin from 7.4 to 2.5 mg/dl. Hemodynamic values were maintained stable throughout the procedure. The patient was able to undergo transplantation and remains alive 11 months later. XHDF is a clinical experimental method that can constitute an alternative clinical therapy to support patients with fulminant hepatic failure until an organ is available for transplantation.

Renal replacement therapies

Slow continuous renal replacement therapy is more hemodynamically stabilizing and is replacing conventional hemodialysis as the therapy of choice for acute renal failure in the intensive care unit. This article presents practical information, including basic terminology, basic physiology, technical aspects, and indications for and application of this technique.

Neurologic complications in the intensive care unit

Neurologic complications resulting from critical illness and intensive care unit therapies are common, but frequently unrecognized because these patients are often intubated, sedated, and, occasionally, receiving neuromuscular blocking agents. Neurologic complications are associated with an increased intensive care unit mortality. This article discusses central nervous system complications that are secondary to critical illness or to therapeutic interventions in the critically ill patient.

Daily hemodialysis: dialysis for the next century

There are currently over 150 patients receiving daily hemodialysis in over 12 centers worldwide. The experiences of over 200 daily hemodialysis patients spanning 30 years have been reviewed. The reports uniformly describe subjective and objective improvements. There are decreased symptoms during and after dialysis, improved functional status, and better quality-of-life ratings. There are improved nutritional indices, improved blood pressure with fewer blood pressure medications, and improved hematocrit with reduced transfusion or eythropoietin requirements. There also appear to be economic advantages, related to the significant reductions in the need for recombinant human erythropoietin and blood pressure medications. Early data suggest that there may be a significant decrease in days of hospitalization for very ill patients as well. This is important clinically and financially when the global costs of caring for dialysis patients are considered. Substantial issues remain before daily hemodialysis will be widely accepted. These include logistical problems (additional time for transportation, set up and disinfection), economic problems (increased supply costs or labor associated with more frequent treatments), and medical problems (deficiency syndromes and blood access). Technological improvements are close to overcoming many of the recognized problems, although additional payor education, research into deficiency syndromes, and an even greater focus on creating natural arterio-venous fistulae all need to occur before daily hemodialysis is more widely accepted. We are convinced, however, that daily dialysis will be increasingly used in the next century because it is more physiologic, makes many patients feel much better, produces better outcomes, and decreases overall cost for end-stage renal disease patients compared with current dialysis regimes.

Treatment of hepatic failure--1996: current concepts and progress toward liver dialysis

Liver failure, especially in its acute form, is a medical emergency that quickly leads to failure of multiple other organs. Many of these end-organ failures can be supported temporarily by drugs or medical devices, but the support is invariably short-lived if liver function is not restored. In most instances, liver function can only be restored by transplantation, although patients with acute disease have the potential to recover by regeneration ("spontaneous recovery"). Unfortunately, spontaneous recovery from acute liver failure is uncommon, so the two most important aspects of patient management are highly skilled intensive care and early recognition of patients in need of liver transplantation. Even under these circumstances, the mortality of liver failure remains high because we have no easy way of replacing liver function on demand and donor organs are becoming increasingly difficult to obtain in time. The development of techniques for liver assist offer the possibility that patients with liver failure will become a simple management problem, analogous to the options available in the treatment of acute and chronic renal failure.