Continuous arteriovenous haemofiltration in patients with hepatic encephalopathy and renal failure

Are Changes in Intracranial Pressure during Intermittent Machine Haemofiltration Dependent upon Membrane Biocompatibility?

We measured the intracranial pressure, using a subdural catheter in three patients admitted with grade 4 hepatic encephalopathy following paracetamol (aminocetaphen) self poisoning. Acute oliguric renal failure was present in all cases and was treated with daily intermittent machine haemofiltration. Hypovolaemia prior to treatment was corrected and a total of 14 isovolaemic 17 litre exchanges carried out using either a Gambro FH77 (8) or Hospal 3600 (6) haemofilter. Intracranial pressure (ICP) increased during treatment with both types of filter, but the increase was greater in the Gambro FH77 treated group, mean ICP increased from 7.6 ± 2 mmHg to 12 ± 3 mmHg at 3 hours (p< 0.05), this was associated with a greater fall in the percentage change from the pretreatment value of both arterial oxygen tension and total peripheral white blood cell count during the first hour of treatment compared to the Hospal 3600 treated group, 8 ± 2% vs 1 ± 2% (p< 0.05) and 5 ± 2% vs 3 ± 2% (p< 0.05).

This suggests that membrane biocompatibility may also play a role in the development of increased intracranial pressure during intermittent machine haemofiltration.

Continuous Renal Replacement Therapy for Acute Renal Failure in Patients with Traumatic Brain Injury

Objective

The purpose of this study was to investigate the impact of continuous renal replacement therapy (CRRT) on survival and relevant factors in patients who underwent CRRT after traumatic brain injury (TBI).

Methods

We retrospectively reviewed the laboratory, clinical, and radiological data of 29 patients who underwent CRRT among 1,190 TBI patients treated at our institution between April 2011 and June 2015. There were 20 men and 9 women, and the mean age was 60.2 years. The mean initial Glasgow Coma Scale score was 9.2, and the mean injury severity score was 24. Kaplan-Meier method and Cox regression were used for analysis of survival and relevant factors.

Results

The actuarial median survival time of the 29 patients was 163 days (range, 3-317). Among the above 29 patients, 22 died with a median survival time of 8 days (range, 3-55). The causes of death were TBI-related in 8, sepsis due to pneumonia or acute respiratory distress syndrome (ARDS) in 4, and multi-organ failure in 10. Among the various factors, urine quantity of more than 500 mL for 24-hours before receiving CRRT was a significant and favorable factor for survival in the multivariate analysis (p=0.026).

Conclusion

According to our results, we suggest that early intervention with CRRT may be beneficial in the treatment of TBI patients with impending acute renal failure (ARF). To define the therapeutic advantages of early CRRT in the TBI patients with ARF, a well-designed and controlled study with more cases is required.

Extracorporeal support for patients with acute and acute on chronic liver failure

The number of patients developing liver failure; acute on chronic liver failure and acute liver failure continues to increase, along with the demand for donor livers for transplantation. As such there is a clinical need to develop effective extracorporeal devices to support patients with acute liver failure or acute-on-chronic liver failure to allow time for hepatocyte regeneration, and so avoiding the need for liver transplantation, or to bridge the patient to liver transplantation, and also potentially to provide symptomatic relief for patients with cirrhosis not suitable for transplantation. Currently devices can be divided into those designed to remove toxins, including plasma exchange, high permeability dialyzers and adsorption columns or membranes, coupled with replacement of plasma proteins; albumin dialysis systems; and bioartificial devices which may provide some of the biological functions of the liver. In the future we expect combinations of these devices in clinical practice, due to the developments in bioartificial scaffolds.

The hemodynamic effects during sustained low-efficiency dialysis versus continuous veno-venous hemofiltration for uremic patients with brain hemorrhage: a crossover study

OBJECT

Hemodynamic instability occurs frequently during dialysis treatment and remains a significant cause of patient morbidity and mortality, especially in patients with brain hemorrhage. This study aims to compare the effects of hemodynamic parameters and intracranial pressure (ICP) between sustained low-efficiency dialysis (SLED) and continuous veno-venous hemofiltration (CVVH) in dialysis patients with brain hemorrhage.

METHODS

End-stage renal disease (ESRD) patients with brain hemorrhage undergoing ICP monitoring were enrolled. Patients were randomized to receive CVVH or SLED on the 1st day and were changed to the other modality on the 2nd day. The ultrafiltration rate was set at between 1.0 kg/8 hrs and 1.5 kg/8 hrs according to the patient's fluid status. The primary study end point was the change in hemodynamics and ICP during the dialytic periods. The secondary end point was the difference between cardiovascular peptides and oxidative and inflammatory assays.

RESULTS

Ten patients (6 women; mean age 59.9 ± 3.6 years) were analyzed. The stroke volume variation was higher with SLED than CVVH (generalized estimating equations method, p = 0.031). The ICP level increased after both SLED and CVVH (time effect, p = 0.003) without significant difference between modalities. The dialysis dose quantification after 8-hour dialysis was higher in SLED than CVVH (equivalent urea clearance by convection, 62.7 ± 4.4 vs 50.2 ± 3.9 ml/min; p = 0.002). Additionally, the endothelin-1 level increased after CVVH treatment (p = 0.019) but not SLED therapy.

CONCLUSIONS

With this controlled crossover study, the authors provide the pilot evidence that both SLED and CVVH display identical acute hemodynamic effects and increased ICP after dialysis in brain hemorrhage patients. CLINICAL TRIAL REGISTRATION NO.: NCT01781585 (ClinicalTrials.gov).

Clinical review: use of renal replacement therapies in special groups of ICU patients

Acute kidney injury (AKI) in ICU patients is typically associated with other severe conditions that require special attention when renal replacement therapy (RRT) is performed. RRT includes a wide range of techniques, each with specific characteristics and implications for use in ICU patients. In the present review we discuss a wide range of conditions that can occur in ICU patients who have AKI, and the implications this has for RRT. Patients at increased risk for bleeding should be treated without anticoagulation or with regional citrate anticoagulation. In patients who are haemodynamically unstable, continuous therapies are most often employed. These therapies allow slow removal of volume and guarantee a stable blood pH. In patients with cerebral oedema, continuous therapy is recommended in order to prevent decreased cerebral blood flow, which will lead to cerebral ischemia. Continuous therapy will also prevent sudden change in serum osmolality with aggravation of cerebral oedema. Patients with hyponatraemia, as in liver failure or decompensated heart failure, require extra attention because a rapid increase of serum sodium concentration can lead to irreversible brain damage through osmotic myelinolysis. Finally, in patients with severe lactic acidosis, RRT can be used as a bridging therapy, awaiting correction of the underlying cause. Especially in ICU patients who have severe AKI, treatment with RRT requires balancing the pros and cons of different options and modalities. Exact and specific guidelines for RRT in these patients are not available for most clinical situations. In the present article we provide an update on the existing evidence.

Extracorporeal support for patients with hepatic failure

Extracorporeal support has been advocated for patients with acute and chronic liver failure. Patients with acute liver failure and those with decompensated cirrhosis can be broadly divided into two groups. The first group comprises those with acute liver failure and ongoing hepatic necrosis, and the second, those with long-standing chronic decompensation admitted with one or more complications of liver failure, such as encephalopathy without any evidence of a precipitating factor or accompanying acute deterioration of liver function. This second group includes patients with acute liver failure, where the insult causing hepatic necrosis has been resolved, and those patients with chronic decompensation who suffer another insult to the liver, such as acute infection or variceal hemorrhage that causes further liver injury in the setting of multiorgan failure. These two groups are likely to have different outcomes and may need to be managed differently. In the first group, liver transplantation is the only possible long-term therapeutic option, whereas in the second group, other possibilities such as extracorporeal liver support systems and/or medical therapy may allow these patients to return to their previous state before the acute insult. Over time extracorporeal support has expanded from simple peritoneal dialysis and hemodialysis, to the development of circuits designed primarily to remove both water and lipid-soluble toxins and, in addition, bioartificial devices to provide replacement synthetic hepatic function. Because many of the patients with an acute liver insult have ongoing chronic liver disease and develop hepatorenal syndrome, this group of patients has been targeted by several groups to study the role of liver support systems.

Continuous renal replacement therapy for liver disease

Continuous renal replacement therapy (CRRT) is becoming the treatment of choice for critically ill patients with acute renal failure around the world. In particular, CRRT is used for patients with combined liver and acute renal failure, because they are often hemodynamically unstable. The question arises as to whether the use of CRRT should be extended to those patients with acute and chronic liver failure who do not have dialysis-dependent renal failure. CRRT could potentially allow some detoxification by removing water-soluble toxins and also allow regulation of intravascular volume and correction of sodium and other electrolyte and acid-base imbalances. By providing homeostatic control, CCRT could potentially help support patients by bridging to liver transplantation and managing those who eventually recover with hepatic regeneration.

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.

Continuous renal replacement therapies in patients with acute neurological injury

Acute neurological injury may occur in patients with end-stage kidney disease on dialysis. Less frequently, acute kidney injury requiring renal dialytic support develops following acute neurological injury. Surrounding any site of neurological injury there is a penumbra of damage which is potentially reversible. To maximize full potential neurological recovery in patients requiring renal dialytic support, it is important that treatments do not themselves cause further cerebral ischemia. Standard intermittent hemodialysis is associated with cerebral swelling even in healthy outpatients and often with episodes of intradialytic hypotension. Continuous modes of renal replacement therapy have been shown to cause fewer surges in intracranial pressure and greater stability of cerebral perfusion pressure than standard intermittent techniques. In patients with acute neurological injury, renal replacement therapy should be carefully adapted to minimize cardiovascular instability and reduce the rate of change of serum osmolality.

Continuous renal replacement therapy in patients following traumatic injury

In critically injured patients, the incidence of acute renal failure has been reported to occur in as many as 31% of patients. The use of CRRT modalities for patients following traumatic injuries is becoming more common, albeit slowly, and this therapy may impact upon long-term recovery of renal function and mortality. Historical studies investigating the early use of intermittent dialysis reported significant improvement in survival in patients who were dialyzed earlier and more vigorously than in control subjects. Early trauma patients also showed improved survival following war injuries when dialyzed prophylactically. Although there is a growing acceptance in favor of earlier renal replacement therapy, the published consensus and the practice in many centers has been to dialyze/filter relatively ill rather than relatively healthy patients. The R Adams Cowley Shock Trauma Center (STC) in Baltimore, Maryland, USA, admits over 8,000 trauma patients each year. Within the STC, a program of continuous renal replacement therapy was established in the early 1980's. We review both historical and current literature on the use of renal replacement therapies after traumatic injury, and suggest some future areas of investigation and indications for these modalities.

Liver failure, transplantation, and critical care

The management of patients for end-stage liver disease in the ICU mandates a multidisciplinary approach and intense monitoring. Orthotopic liver transplantation still remains the only definitive therapy. Given the increasing disparity between the number of potential recipients and available cadaver organs, the current challenge is to optimize outcome with the limited resource. In recent years, considerable progress has been made in developing specific and supportive medical measures. Future research should target a better understanding of mechanisms responsible for liver cell death and liver regeneration, as well as developments in xenotransplantation, hepatocyte transplantation, and liver-directed gene therapy.

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 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

Fulminant hepatic failure is a disease of varied causes and a high mortality rate. A sudden onset, jaundice, hepatic encephalopathy, and multiorgan failure are the hallmarks of this syndrome. The management of patients with FHF requires a multidisciplinary approach and intense monitoring. The availability of liver transplantation has provided the means to rescue such patients from near-certain death. Early prognostication and timely availability of donor livers are requirements for a successful outcome. The development of effective artificial liver support devices may greatly prolong the window of opportunity to provide a donor liver, or alternatively, to allow the native liver to regenerate.

Cerebral function analyzing monitor and visual evoked potentials as a noninvasive method of detecting cerebral dysfunction in patients with acute hepatic and renal failure treated with intermittent machine hemofiltration

We monitored the effect of 7 intermittent machine hemofiltration treatments in 4 patients with fulminant hepatic failure who had progressed to grade IV coma and developed acute oliguric renal failure. Prior to treatment the processed EEG showed excess slow wave activity, and the latency of the later visual evoked potentials (N2 and P2) was delayed. Following treatment there was a further increase in both EEG slow wave activity and latency of the N1, N2, and P2 potentials. Intracranial pressure increased from a median of 8 mm Hg (2-12, range) to 14 (8-28) following treatment, p < 0.05. There was a correlation between intracranial pressure and all of the later visual evoked potentials, for N3 r = 0.71, for P1 r = 0.39, and P2 r = 0.74, all p < 0.05. Although there appeared to be a good correlation between intracranial pressure and the noninvasive electrophysiological recordings, there were major changes in intracranial pressure, cerebral perfusion pressure, and cerebrospinal fluid pH during the first hour of treatment, during which time there were no discernable changes in EEG or evoked potentials. In this study, non-invasive neurophysiological methods were not found to be reliable as invasive methods in assessing acute, minute-by-minute changes in cerebral metabolism but these methods may have a role in the longer term in assessing patient prognosis.

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.

Continuous arteriovenous hemofiltration

CAVH is a bedside form of dialysis that is used in the treatment of fluid and electrolyte disorders seen in critically ill patients. The major advantages of the procedure include (1) gradual, continuous therapy, which is ideal in hemodynamically unstable patients; (2) control of fluid balance; and (3) ease of administration in the ICU. The major disadvantages of CAVH include (1) a requirement for arterial access, (2) the need for anticoagulation, (3) the risks of infection from long-term indwelling vascular lines, and (4) the potential for significant volume depletion. The effectiveness of CAVH may continue to improve owing to technical developments in filter composition and the application of clinical tactics such as suction-assisted filtration, predilution fluid replacement, or regional heparinization. The next step in bedside dialysis is represented by CAVHD, which offers all of the advantages of CAVH as well as improved urea clearance.

Rebound surges of intracranial pressure as a consequence of forced ultrafiltration used to control intracranial pressure in patients with severe hepatorenal failure

Cerebral edema remains the most common immediate cause of death in patients with fulminant hepatic failure. We have used ultrafiltration as a method of controlling intracranial pressure (ICP) when other measures have failed. Two cases in which an initial decrease in ICP was followed by a marked rebound increase resulting in death are reported.