Changing the hemodialysis prescription for hemodialysis patients with subdural and intracranial hemorrhage

Although continuous modalities of renal replacement therapy offer an advantage to the patient with compromised cerebral perfusion and intracranial hypertension, they are generally limited to the intensive care unit setting. Many hemodialysis patients admitted with strokes and subdural hematoma are managed on general wards. As such, these patients are generally treated by intermittent hemodialysis, and their dialysis prescription should be altered to minimize changes in serum osmolality, and fall in blood pressure during dialysis. Such patients require more frequent but shorter dialysis sessions, using minimally bioincompatible small surface area dialyzers with lower blood flows, in combination with higher sodium and cooled dialysate. In patients at risk of intracranial hemorrhage and those with invasive intracranial monitoring, systemic anticoagulants should be avoided, choosing no anticoagulation protocols or regional anticoagulants.

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.

Mathematical Modeling in Cardiac Surgery: Helping Clinical Trials Answer the Question

Mathematical modeling, based on fundamental principles from engineering may help clinical trial design, aiding in answering problems that remain in cardiac surgery, such as management of carotid artery stenosis in patients undergoing cardiopulmonary bypass (CPB), hematocrit during CPB, adequacy of oxygen delivery during CPB, adequacy of blood pressure management during CPB, filtration during bypass for renal failure, bypass circuit pacification, carbon dioxide wound insufflation and neurological events, and pulsatile to nonpulsatile flow during CPB. In addition, mathematical modeling may help explain deficiencies of previous work that have failed to clarify what to do.

Renal replacement therapy in patients with chronic liver disease

As the prevalence of chronic liver disease and chronic kidney disease (CKD) increase, clinicians are likely to be increasingly faced with difficult diagnostic, treatment, and ethical challenges when facing both of these diseases in a single patient. Alterations in creatinine formation and elimination in cirrhotic patients render creatinine-based estimates of glomerular filtration rate and dialysis adequacy less accurate in this population. Furthermore, differentiating signs and symptoms of uremia from hepatic disease may be difficult and clear indications for renal replacement therapy (RRT) in these patients have not been defined. Hemodialysis is associated with a high rate of complications and has not been shown to prolong life in cirrhotic patients with acute renal failure (ARF), but has not been carefully examined in those with CKD. Peritoneal dialysis is, similarly, unhelpful in chronic liver disease complicated by ARF, but has been found to be a viable option in some cirrhotic patients with CKD. Continuous RRT is generally tolerated by patients with decompensated cirrhosis and either acute or chronic renal failure and may act to bridge patients to liver transplantation. Given the poor underlying survival of cirrhotic patients with renal failure, clinicians should carefully consider the utility of RRT in each patient.

Kidney failure associated with liver transplantation or liver failure: the impact of continuous veno-venous hemofiltration

BACKGROUND AND AIMS

The short-term outcome of critically ill patients with kidney failure combined with severe liver failure or orthotopic liver transplantation (OLTx) is poor. We sought to test the hypothesis that, with the exclusive use of continuous veno-venous hemofilration (CVVH) with minimal heparin-anticoagulation, the short and long-term outcomes of these patients would be improved.

PATIENTS

Sixty-six consecutive patients with combined liver and kidney failure

SETTING

Intensive Care Unit of tertiary hospital

DESIGN

Retrospective interrogation of prospectively collected databases

INTERVENTION

Treatment of all patients with continuous veno-venous hemofiltration (CVVH) by protocol with 2L/h of ultrafiltration rate and minimal use of circuit heparinization. Retrieval of specific information on demographic, clinical, therapeutic and outcome details.

MEASUREMENTS AND MAIN RESULTS

From July 1995 to April 2004, 66 patients with combined liver and renal failure received continuous veno-venous hemofiltration (CVVH). Of these, 26 received liver transplantation and 40 did not. There were no significant differences in age, APACHE II score, bilirubin, ALT, INR or albumin on admission. The average duration of CVVH was 9.5 days for OLTx patients and 5 days for non-transplanted patients (p=0.013). Heparin anticoagulation was used in only 12% of OLTx patients and 20% of non-transplanted patients. ICU mortality was 15% in OLTx patients and 63% in non-transplanted patients (p<0.0005); hospital mortality was 23% compared to 70% (p<0. 001). Mean survival time at follow up was 1,120 days compared to 358 days (p<0.0001).

CONCLUSIONS

ARF associated with OLTx has a much better outcome than ARF without OLTx. Furthermore, management based on a conservative anticoagulation policy and CVVH as the exclusive form of renal support was associated with the best ICU, hospital and long term survival reported so far.

The first international consensus conference on continuous renal replacement therapy

BACKGROUND

Management of acute renal failure (ARF) in the critically ill is extremely variable and there are no published standards for the provision of renal replacement therapy in this population. We sought to review the available evidence, make evidence-based practice recommendations, and delineate key questions for future study.

METHODS

We undertook an evidence-based review of the literature on continuous renal replacement therapy (CRRT) using MEDLINE searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated practice guidelines and/or directions for future research.

RESULTS

Of the 46 questions considered, we found consensus for 20. We found inadequate evidence for 21 questions and for the remaining five we found data but no consensus. Full versions of workgroup findings are available on the Internet at http://www.ADQI.net.

CONCLUSIONS

Despite limited data, broad areas of consensus exist for use of CRRT and guideline development appears feasible. Equally broad areas of disagreement also exist and additional basic and applied research in acute renal failure is needed.

The Acute Dialysis Quality Initiative--part II: patient selection for CRRT

The delivery of optimal acute dialytic support requires that the correct patients be selected for such treatment in a timely fashion and that such treatment be delivered at the appropriate dose, for an appropriate length of time, and for the appropriate indications. The Acute Dialysis Quality Initiative sought to address these issues through an expert-enhanced review of the literature. This article represents a condensation of its findings with regard to patients selection for CRRT, indications for initiation of treatment, transition to other treatments, cessation of treatment, and availability of continuous therapy. The article offers recommendations for clinical practice based on the findings of the expert group. It also offers suggestions and sets priorities for future research in this important area of critical care nephrology.

Hepatorenal syndrome. Definition, pathophysiology, and intervention

Hepatorenal syndrome is a well characterized entity in which vasodilation of splanchnic vessels and intense constriction of the renal cortical vasculature occur in concert. The condition is often fatal unless orthotopic liver transplantation (OLT) is performed. Many extracorporeal blood purification techniques exist which can be offered to patients awaiting OLT. Continuous hemofiltration, with or without other modalities such as therapeutic plasma exchange and hemoperfusion, may be helpful in improving the level of consciousness of these patients. Unfortunately, mortality and hepatic regeneration do not appear to be affected by such interventions. The development of a hybrid bioartifical liver support system and pharmacologic manipulation of the hemodynamic perturbations that occur in HRS provide particularly appealing prospects as a means of providing a bridge to liver transplantation in the future.

Renal replacement therapy and orthotopic liver transplantation: the role of continuous veno-venous hemodialysis

BACKGROUND

The need for renal replacement therapy (RRT) either before or after orthotopic liver transplant (OLTX) has been reported to be a poor prognostic indicator for survival. Use of continuous veno-venous hemodialysis (CVVHD) for RRT has been reported in three series of OLTX patients with high 90-day mortality rates of 57-60%. We have examined our patient population to determine the effect of necessity and type of RRT on patient survival after OLTX.

METHODS

We analyzed 1535 OLTX that were performed at our institution from 1985 through 1999, 1037 from 1985 to 1995 (period I) and 498 from 1996 to 1999 (period II). Combined liver-kidney transplants were excluded from analysis. Hospital dialysis unit records and a prospectively maintained database on all OLTX patients served as the source of data. Patients were classified into groups defined on whether or not they received RRT, when they received RRT, and the type of RRT. Groups were compared for preoperative intensive care unit status, time on the waiting list, laboratory variables, 90-day postoperative mortality, 1-year patient survival, and absolute survival.

RESULTS

Use of RRT increased from 8.29% in period I to 12.45% in period II, along with increased median waiting times. In period I, patients receiving preoperative RRT had a 90-day mortality (0%) and a 1-year survival (89.5%) almost identical to those patients who never required RRT (1.7% and 90.6%). Patients who developed acute renal failure postoperatively requiring RRT, however, had a 90-day mortality of 28.6% and a 1-year survival of 55%. In period II, patients requiring RRT had a 90-day mortality of 39.7% and a 1-year actuarial survival of 54.5% compared with 6.9% and 88.6% in patients never requiring RRT. Patients treated with CVVHD had a 90-day mortality of 42% compared with 25% in patients treated with hemodialysis alone. However, patients receiving CVVHD both pre- and postoperatively had a 90-day mortality of 27.7% vs. 50% in those patients who only received CVVHD postoperatively. Patients who developed acute renal failure postoperatively, which required RRT, regardless of therapy, had a 1-year survival of only 41.0% compared with a 1-year survival of 73.6% in those patients started on RRT preoperatively, P=0.03.

CONCLUSIONS

The need for RRT has increased along with waiting time in OLTX patients. Patients developing the need for RRT postoperatively have an increased 90-day mortality and lower 1-year survival with the highest being present in patients receiving CVVHD, which was started postoperatively. These findings may reflect a trend toward a sicker population awaiting OLTX and emphasize the negative impact of renal failure on survival after OLTX.

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.

Fulminant hepatic failure

In recent years, considerable progress has been made in developing specific and supportive medical measures that have improved prognosis in FHF. Although new techniques for cell culture and perfusion have also resulted in a number of promising devices for the provision of temporary liver support, their clinical efficacy is as yet uncertain. Controlled multicenter trials in well-defined patient groups and with standardized outcome measures will be essential to evaluate the clinical value of these devices properly. The same considerations must also apply in assessing the efficacy of hepatocyte transplantation in FHF. A better understanding of mechanisms responsible for liver cell death and multiorgan failure, and the development of strategies to enhance liver regeneration may, in the future, allow a more targeted approach to therapy.

Review article: liver support systems in acute hepatic failure

The treatment of acute hepatic failure has developed rapidly over the last 40 years, reducing morbidity and mortality from this syndrome. Whilst this has been partly attributed to significant improvements in the specialist medical management of these patients, advances in surgical techniques and pharmaceutical developments have led to the establishment of successful liver transplantation programmes, which have improved mortality significantly. This review will examine the clinical impact of alternative methods that have been used to provide extra-corporeal hepatic support. Non-biological, bio- logical and hybrid hepatic extra-corporeal support will be explored, offering a comprehensive historical overview and an appraisal of present and future advances.

Review article: the management of acute liver failure

Acute liver failure (ALF) is a relatively uncommon but dramatic clinical syndrome with high mortality rates, in which a previously normal liver fails within days or weeks. Paracetamol overdose remains the major cause of ALF in the UK, while viral hepatitis is the commonest cause world-wide. Cerebral oedema is the leading cause of death in patients with ALF. Despite advances in intensive care and the development of new treatment modalities, ALF remains a condition of high mortality best managed in specialist centres. Orthotopic liver transplantation is the only new treatment modality that has made a significant impact in improving outcome. Bioartificial liver support systems and hepatocyte transplantation are new promising treatment options that may change the management of ALF in the future.

Fulminant hepatic failure

Fulminant hepatic failure is a devastating illness that carries considerable mortality and affects patients with previously healthy livers. Although the etiology of FHF remains unclear in a significant number of cases, viral hepatitis and drug-induced liver injury account for the majority of identifiable causes. The clinical presentation varies widely, but is always characterized by the presence of encephalopathy. Markedly elevated transaminases are seen, but do not correlate with extent of liver injury. Prothrombin time, bilirubin, creatinine, and arterial pH are prognostic indicators of survival in FHF. FHF and its consequences must be readily recognized so that appropriate triage and treatment can be administered. All patients should be managed in an intensive care setting pending transfer to a liver transplantation center. Supportive care remains the mainstay of treatment, with liver transplantation reserved for select patients.

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.

Critical care in uraemic children

The special problems posed by renal disease have to be considered when a uraemic child requires intensive care. This report gives an overview on the problems of dialysis treatment, circulatory support, infectious complications, coagulation disorders and increased intracranial pressure.