Recovery despite impaired cerebral perfusion in fulminant hepatic failure

Super resolution imaging reconstruction reveals that gold standard methods may not correctly conclude neural/brain functional recovery

The status of cerebral perfusion and its restoration level play a vital role in the prognosis and clinical decision making of many neurosurgical diseases. As such, gold standard methods including CT, MR and ICP monitoring, which can indicate and measure cerebral perfusion and restoration, have been widely adopted to evaluate whether or not a patient has recovered from neurofunctional disabilities. This robust combination of methods, however, is confronted with a growing number of contradictions in recent years due to its inability to measure the status of cerebral reperfusion in microvasculature level, even though this has been shown to determine neurofunctional restoration as well or even better. To this date, nevertheless, we have very limited imaging methods that could evaluate human cerebral microperfusion both safely and accurately under most neurosurgical conditions. We herein report a new method of acquiring a patient's cerebral microperfusion status noninvasively which could display the precise distribution of microvasculature in deep cerebral regions with a resolution of ∼30 µm, using everyday bed-side ultrasonography combined with a computerized super-resolution reconstruction algorithm. Using this imaging modality, we found that a patient's cerebral microperfusion might not be improved by some routine administrations even though the gold standard method had yielded the opposite conclusions. Our imaging modality retains the safe, portable feature of ordinary ultrasonography while possesses the extraordinary super-resolution nature, which enables an efficient, precise diagnosis of cerebral perfusion. Most importantly, the super resolution nature of this method may also facilitate early-stage evaluation of a patient's neurofunctional restoration level and avoid overoptimistic conclusions from conventional angiography or ICP monitoring.

Protocol based invasive intracranial pressure monitoring in acute liver failure: feasibility, safety and impact on management

Background

Acute liver failure (ALF) may result in elevated intracranial pressure (ICP). While invasive ICP monitoring (IICPM) may have a role in ALF management, these patients are typically coagulopathic and at risk for intracranial hemorrhage (ICH). Contemporary ICP monitoring techniques and coagulopathy reversal strategies may be associated with a lower risk of hemorrhage. Our objective was to evaluate the safety, feasibility, impact on clinical management and outcomes associated with protocol-directed use of IICPM in ALF.

Methods

Adult patients admitted between June 2011 and October 2016, with ALF and grade-4 encephalopathy with a reasonable likelihood of survival, were eligible for IICPM. The coagulopathy reversal protocol included administration of recombinant Factor VIIa (rFVIIa) and desmopressin, a goal platelet count >50,000/mm³ and fibrinogen >100 mg/dL. Monitor insertion was performed within an hour of the rFVIIa dose. Only intraparenchymal monitors were used. Computed tomography of the brain was performed prior to and within 24 hours of monitor placement. Outcomes of interest included ICH, sustained intracranial hypertension, therapeutic intensity level (TIL) for ICP management, mortality and functional outcome on the Glasgow Outcome Scale (GOS) at discharge and 6 months.

Results

A total of 24/37 patients (65%) with ALF underwent IICPM. The most common reason for exclusion was encephalopathy grade <4. Four patients underwent liver transplantation. There was one asymptomatic ICH following IICPM, in a patient who had an excellent outcome. Sustained intracranial hypertension occurred in 13/24 monitored patients (54%), 5/24 (21%) required extreme measures (TIL-4) for ICP control, which were successful in 4 patients: 12/24 patients (50%) died but only 4 deaths (17%) were attributed to intracranial hypertension. Six of the 8 survivors with 6-month follow up had good functional outcome (GOS >3).

Conclusions

Protocol-directed use of IICPM in ALF is feasible, associated with a low incidence of serious complications and has a significant impact on clinical management.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

Multimodal brain monitoring in fulminant hepatic failure

Acute liver failure, also known as fulminant hepatic failure (FHF), embraces a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction, and hepatic encephalopathy. Cerebral edema and intracranial hypertension are common causes of mortality in patients with FHF. The management of patients who present acute liver failure starts with determining the cause and an initial evaluation of prognosis. Regardless of whether or not patients are listed for liver transplantation, they should still be monitored for recovery, death, or transplantation. In the past, neuromonitoring was restricted to serial clinical neurologic examination and, in some cases, intracranial pressure monitoring. Over the years, this monitoring has proven insufficient, as brain abnormalities were detected at late and irreversible stages. The need for real-time monitoring of brain functions to favor prompt treatment and avert irreversible brain injuries led to the concepts of multimodal monitoring and neurophysiological decision support. New monitoring techniques, such as brain tissue oxygen tension, continuous electroencephalogram, transcranial Doppler, and cerebral microdialysis, have been developed. These techniques enable early diagnosis of brain hemodynamic, electrical, and biochemical changes, allow brain anatomical and physiological monitoring-guided therapy, and have improved patient survival rates. The purpose of this review is to discuss the multimodality methods available for monitoring patients with FHF in the neurocritical care setting.

Therapeutic hypothermia in acute liver failure: a multicenter retrospective cohort analysis

The benefit of therapeutic hypothermia (TH) in acute liver failure (ALF) has not been previously demonstrated in a controlled fashion. This study sought to determine the impact of TH on 21-day survival and complications in ALF patients at high risk for cerebral edema. This was a retrospective cohort study of ALF patients in the US Acute Liver Failure Study Group with grade III or IV hepatic encephalopathy. TH (32°C-35°C) was used in 97 patients (8%); 1135 (92%) who were not cooled were controls. Intracranial pressure was monitored in 38 TH ALF patients (39.2% versus 22% of controls, P < 0.001). Rates of bleeding (12% for both) and bloodstream (17% versus 18%) and tracheal infections (21% versus 23%, P > 0.5 for all) were similar. Unadjusted 21-day overall (62% versus 60%) and transplant-free survival rates (45% versus 39%, P > 0.4 for both) were similar. Multivariate models were created for acetaminophen (APAP) patients (n = 582) and non-APAP patients (n = 613). For APAP patients, the Model for End-Stage Liver Disease [MELD; odds ratio (OR) = 0.91 per increment, 95% confidence interval (CI) = 0.89-0.94, P < 0.001] and vasopressors (OR = 0.16, 95% CI = 0.11-0.24, P < 0.001) were associated with decreased 21-day spontaneous survival. Survival was improved with TH in APAP patients who were <25 years old (age of 25 years: OR = 2.735, 95% CI = 1.001-7.467) but worsened for APAP patients who were 64 years old or older (age of 64 years: OR = 0.167, 95% CI = 0.028-0.999). For non-APAP patients, MELD (OR = 0.93 per increment, 95% CI = 0.91-0.95, P < 0.001) and vasopressors (OR = 0.60, 95% CI = 0.40-0.90, P = 0.01) were associated with worse outcomes, whereas TH had no impact (P = 0.93). In conclusion, TH in ALF was not associated with increased bleeding or infections. Although young APAP ALF patients may benefit, TH did not consistently affect 21-day survival. A prospective trial is required to clarify the utility of TH in ALF patients.

The brain in acute on chronic liver failure

Acute-on-chronic liver failure (ACLF) is a newly defined clinical entity with significant morbidity and mortality (~40-90% at 1 year dependent on need for organ support at presentation). It defines a presentation with acute severe liver injury, often with multiorgan dysfunction, on a background of previously known or unknown cirrhosis. In its severest form, it is almost indistinguishable from acute liver failure, as similarly in around 5% may rapidly progress to intracranial hypertension and cerebral oedema culminating in coma and/or death. Our understanding of such cerebral sequelae is currently limited to clinical observation, though our knowledge base is rapidly expanding since recent consensus clinical definition and guidance. Moreover, there are now animal models of ACLF and imaging modalities to better characterize events in the brain that occur with ACLF. However, as yet there has been little in the way of interventional study of this condition which are much needed. In this review we dissect existing clinical and experimental data to better characterise the manifestations of ACLF on the brain and allow for the development of targeted therapy as currently the plethora of existing interventions were designed to treat either the effects of cirrhosis or acute liver injury independently.

Update in intensive care medicine: acute liver failure. Initial management, supportive treatment and who to transplant

PURPOSE OF REVIEW

Acute liver failure (ALF) is associated with significant mortality. Although specific therapies may be available, the evidence base for these and for many aspects of supportive therapy has been slow to emerge. Liver transplantation continues to be a cornerstone of treatment, and the management of ALF, therefore, remains the domain of the specialist ICU. The purpose of this review is to identify and critically appraise the recent evidence and to inspire those who strive to provide excellent care for a difficult patient cohort.

RECENT FINDINGS

Effective vaccination programmes have reduced the incidence of viral hepatitis in Europe and the USA. Spontaneous survival has improved in causes such as acetaminophen toxicity. Early recognition and proactive intensive management have reduced the incidence of early neurological death. The use of artificial liver assist devices and therapeutic plasma exchange is controversial, yet intriguing, with some early evidence of efficacy.

SUMMARY

Increasingly sophisticated prognostication tools are evolving, which have the potential to transform clinical decision-making. A review of the indications for transplantation in acetaminophen toxicity is overdue. The use of therapeutic plasma exchange and extracorporeal liver support in ALF requires further investigation.

Outcomes and complications of intracranial pressure monitoring in acute liver failure: a retrospective cohort study

OBJECTIVE

To determine if intracranial pressure monitor placement in patients with acute liver failure is associated with significant clinical outcomes.

DESIGN

Retrospective multicenter cohort study.

SETTING

Academic liver transplant centers comprising the U.S. Acute Liver Failure Study Group.

PATIENTS

Adult critically ill patients with acute liver failure presenting with grade III/IV hepatic encephalopathy (n = 629) prospectively enrolled between March 2004 and August 2011.

INTERVENTION

Intracranial pressure monitored (n = 140) versus nonmonitored controls (n = 489).

MEASUREMENTS AND MAIN RESULTS

Intracranial pressure monitored patients were younger than controls (35 vs 43 yr, p < 0.001) and more likely to be on renal replacement therapy (52% vs 38%, p = 0.003). Of 87 intracranial pressure monitored patients with detailed information, 44 (51%) had evidence of intracranial hypertension (intracranial pressure > 25 mm Hg) and overall 21-day mortality was higher in patients with intracranial hypertension (43% vs 23%, p = 0.05). During the first 7 days, intracranial pressure monitored patients received more intracranial hypertension-directed therapies (mannitol, 56% vs 21%; hypertonic saline, 14% vs 7%; hypothermia, 24% vs 10%; p < 0.03 for each). Forty-one percent of intracranial pressure monitored patients received liver transplant (vs 18% controls; p < 0.001). Overall 21-day mortality was similar (intracranial pressure monitored 33% vs controls 38%, p = 0.24). Where data were available, hemorrhagic complications were rare in intracranial pressure monitored patients (4 of 56 [7%]; three died). When stratifying by acetaminophen status and adjusting for confounders, intracranial pressure monitor placement did not impact 21-day mortality in acetaminophen patients (p = 0.89). However, intracranial pressure monitor was associated with increased 21-day mortality in nonacetaminophen patients (odds ratio, ~ 3.04; p = 0.014).

CONCLUSIONS

In intracranial pressure monitored patients with acute liver failure, intracranial hypertension is commonly observed. The use of intracranial pressure monitor in acetaminophen acute liver failure did not confer a significant 21-day mortality benefit, whereas in nonacetaminophen acute liver failure, it may be associated with worse outcomes. Hemorrhagic complications from intracranial pressure monitor placement were uncommon and cannot account for mortality trends. Although our results cannot conclusively confirm or refute the utility of intracranial pressure monitoring in patients with acute liver failure, patient selection and ancillary assessments of cerebral blood flow likely have a significant role. Prospective studies would be required to conclusively account for confounding by illness severity and transplant.

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.

Management of hepatic encephalopathy

Hepatic encephalopathy (HE), the neuropsychiatric presentation of liver disease, is associated with high morbidity and mortality. Reduction of plasma ammonia remains the central therapeutic strategy, but there is a need for newer novel therapies. We discuss current evidence supporting the use of interventions for both the general management of chronic HE and that necessary for more acute and advanced disease.

Critical care management of patients before liver transplantation

The critical care management of patients before liver transplantation is aimed at optimizing hepatic and extrahepatic organ function before the transplant operation, with a goal to favorably influence perioperative and postoperative graft and patient outcomes. Critical illness in liver disease can present in the context of acute liver failure or acute on chronic liver failure. The differing pathophysiologic processes underlying these 2 types of liver failure necessitate specific approaches to their intensive care management. In their extreme presentations, both types of liver failure present as multiorgan system failure; and therefore, the critical care management of these entities requires a systematic multiorgan system approach to address hepatic and extrahepatic organ dysfunction. This review provides a multiorgan system-based description of critical care management of acute liver failure and acute on chronic liver failure before liver transplantation.

Management of acute liver failure

Acute liver failure (ALF) is a syndrome of diverse etiology, in which patients without previously recognized liver disease sustain a liver injury that results in rapid loss of hepatic function. Depending on the etiology and severity of the insult, some patients undergo rapid hepatic regeneration and spontaneously recover. However, nearly 60% of patients with ALF in the US require and undergo orthotopic liver transplantation or die. Management decisions made by clinicians who initially assess individuals with ALF can drastically affect these patients' outcomes. Even with optimal early management, however, many patients with ALF develop a cascade of complications often presaged by the systemic inflammatory response syndrome, which involves failure of nearly every organ system. We highlight advances in the intensive care management of patients with ALF that have contributed to a marked improvement in their overall survival over the past 20 years. These advances include therapies that limit the extent of liver injury and maximize the likelihood of spontaneous recovery and approaches to enable prevention, recognition and early treatment of complications that lead to multi-organ-system failure, the most common cause of death. Finally, we summarize the role of orthotopic liver transplantation in salvage of the most severely affected patients.

Critical management decisions in patients with acute liver failure

Few admissions to the ICU present a greater clinical challenge than the patient with acute liver failure (ALF), the syndrome of abrupt loss of liver function in a previously unaffected individual. Although advances in the intensive care management of patients with ALF have improved survival, the prognosis of ALF remains poor, with a 33% mortality rate and a 25% liver transplant rate in the United States. ALF adversely affects nearly every organ system, with most deaths occurring from sepsis and subsequent multiorgan system failure, and cerebral edema, resulting in intracranial hypertension (ICH) and brainstem herniation. Unfortunately, the optimal management of ALF remains poorly defined, and practices are often based on local experience and case reports rather than on randomized, controlled clinical trials. The paramount question in any patient presenting with ALF remains defining an etiology, since specific antidotes can save lives and spare the liver. This article will consider recent advances in the assignment of an etiology, the administration of etiology-specific treatment to abate the liver injury, and the management of complications (eg, infection, cerebral edema, and the bleeding diathesis) in patients with ALF. New data on the administration of N-acetylcysteine to patients with non-acetaminophen ALF, the treatment of ICH, and assessment of the need for liver transplantation will also be presented.

Intensive care management of acute liver failure

PURPOSE OF REVIEW

The mortality of acute liver failure remains unacceptably high and liver transplantation is the only effective treatment available to date. This review focuses on new research developments in the field and aims to provide a pragmatic organ-based treatment approach for liver failure patients requiring intensive care support.

RECENT FINDINGS

The pathophysiological basis for cerebral edema formation in acute liver failure continued to be the focus of various investigations. In-vivo observations confirmed the link between ammonia, cerebral glutamine content and intracranial hypertension. The role of arterial ammonia as an important prognostic indicator formed the basis of prospective, observational studies. Reduced monocytic HLA-DR expression linked acute liver failure with poor prognosis, and the cerebral effects and side effects of vasoactive therapy with terlipressin were investigated with two studies showing contradictory results.

SUMMARY

Despite increased knowledge of the pathophysiological events leading to organ dysfunction in acute liver failure, supportive treatment options remain limited in their efficacy and largely noncurative.

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.

Therapy of intracranial hypertension in patients with fulminant hepatic failure

Severe intracranial hypertension (IH) in the setting of fulminant hepatic failure (FHF) carries a high mortality and is a challenging disease for the critical care provider. Despite considerable improvements in the understanding of the pathophysiology of cerebral edema during liver failure, therapeutic maneuvers that are currently available to treat this disease are limited. Orthotopic liver transplantation is currently the only definitive therapeutic strategy that improves outcomes in patients with FHF. However, many patients die prior to the availability of donor organs, often because of cerebral herniation. Currently, two important theories prevail in the understanding of the pathophysiology of IH during FHF. Ammonia and glutamine causes cytotoxic cerebral injury while cerebral vasodilation caused by loss of autoregulation increases intracranial pressure (ICP) and predisposes to herniation. Although ammonia-reducing strategies are limited in humans, modulation of cerebral blood flow seems promising, at least during the early stages of hepatic encephalopathy. ICP monitoring, transcranial Doppler, and jugular venous oximetry offer valuable information regarding intracranial dynamics. Induced hypothermia, hypertonic saline, propofol sedation, and indomethacin are some of the newer therapies that have been shown to improve survival in patients with severe IH. In this article, we review the pathophysiology of IH in patients with FHF and outline various therapeutic strategies currently available in managing these patients in the critical care setting.

Complications and use of intracranial pressure monitoring in patients with acute liver failure and severe encephalopathy

Monitoring of intracranial pressure (ICP) in acute liver failure (ALF) is controversial as a result of the reported complication risk (approximately 20%) and limited therapeutic options for intracranial hypertension. Using prospectively collected information from 332 patients with ALF and severe encephalopathy, we evaluated a recent experience with ICP monitoring in the 24 centers constituting the U.S. ALF Study Group. Special attention was given to the rate of complications, changes in management, and outcome after liver transplantation (LT). ICP monitoring was used in 92 patients (28% of the cohort), but the frequency of monitoring differed between centers (P < 0.001). ICP monitoring was strongly associated with the indication of LT (P < 0.001). A survey performed in a subset of 58 patients with ICP monitoring revealed intracranial hemorrhage in 10.3% of the cohort, half of the complications being incidental radiological findings. However, intracranial bleeding could have contributed to the demise of 2 patients. In subjects listed for LT, ICP monitoring was associated with a higher proportion of subjects receiving vasopressors and ICP-related medications. The 30-day survival post-LT was similar in both monitored and nonmonitored groups (85% vs. 85%). In conclusion, the risk of intracranial hemorrhage following ICP monitoring may have decreased in the last decade, but major complications are still present. In the absence of ICP monitoring, however, patients listed for LT appear to be treated less aggressively for intracranial hypertension. In view of the high 30-day survival rate after LT, future studies of the impact of intracranial hypertension should also focus on long-term neurological recovery from ALF.

Management of patients with fulminant hepatic failure and brain edema

Cerebral edema in acute liver failure is associated with a poor prognosis. Optimization of cerebral perfusion pressure and blood flow plays a key role in contemporary management of these patients. However, understanding of the pathophysiology of brain edema is required for optimal patient management. This review explains the relationships between cerebral perfusion and edema and summarizes therapies that are currently used in patients with acute liver failure to prevent and reduce intracranial pressure.

Moderate hypothermia in patients with acute liver failure and uncontrolled intracranial hypertension

BACKGROUND AND AIMS

About 20% of patients with acute liver failure (ALF) die from increased intracranial pressure (ICP) while awaiting transplantation. This study evaluates the clinical effects and pathophysiologic basis of hypothermia in patients with ALF and intracranial hypertension that is unresponsive to standard medical therapy.

METHODS

Fourteen patients with ALF who were awaiting orthotopic liver transplantation (OLT) and had increased ICP that was unresponsive to standard medical therapy were studied. Core temperature was reduced to 32 degrees C-33 degrees C using cooling blankets.

RESULTS

Thirteen patients were successfully bridged to OLT with a median of 32 hours (range, 10-118 hours) of cooling. They underwent OLT with no significant complications related to cooling either before or after OLT and had complete neurologic recovery. ICP before cooling was 36.5 +/- 2.7 mm Hg and was reduced to 16.3 +/- .7 mm Hg at 4 hours, which was sustained at 24 hours (16.8 +/- 1.5 mm Hg) ( P < .0001). Mean arterial pressure and cerebral perfusion pressure increased significantly, and the requirement for inotropes was reduced significantly. Hypothermia produced sustained and significant reduction in arterial ammonia concentration and its brain metabolism, cerebral blood flow, brain cytokine production, and markers of oxidative stress.

CONCLUSIONS

Moderate hypothermia is an effective and safe bridge to OLT in patients with ALF who have increased ICP that is resistant to standard medical therapy. Hypothermia reduces ICP by impacting on multiple pathophysiologic mechanisms that are believed to be important in its pathogenesis. A large multicenter trial of hypothermia in ALF is justified.

Regional cerebral blood flow autoregulation in patients with fulminant hepatic failure

The absence of cerebral blood flow autoregulation in patients with fulminant hepatic failure (FHF) implies that changes in arterial pressure directly influence cerebral perfusion. It is assumed that dilatation of cerebral arterioles is responsible for the impaired autoregulation. Recently, frontal blood flow was reported to be lower compared with other brain regions, indicating greater arteriolar tone and perhaps preserved regional cerebral autoregulation. In patients with severe FHF (6 women, 1 man; median age, 46 years; range, 18 to 55 years), we tested the hypothesis that perfusion in the anterior cerebral artery would be less affected by an increase in mean arterial pressure compared with the brain area supplied by the middle cerebral artery. Relative changes in cerebral perfusion were determined by transcranial Doppler-measured mean flow velocity (V(mean)), and resistance was determined by pulsatility index in the anterior and middle cerebral arteries. Cerebral autoregulation was evaluated by concomitant measurements of mean arterial pressure and V(mean) in the anterior and middle cerebral arteries during norepinephrine infusion. Baseline V(mean) was lower in the brain area supplied by the anterior cerebral artery compared with the middle cerebral artery (median, 47 cm/s; range, 21 to 62 cm/s v 70 cm/s; range 43 to 119 cm/s, respectively; P <.05). Also, vascular resistance determined by pulsatility index was greater in the anterior than middle cerebral artery (median, 1.02; range 1.00 to 1.37 v 0.87; range 0.75 to 1.48; P <.01). When arterial pressure was increased from 84 mm Hg (range 57 to 95 mm Hg) to 115 mm Hg (range, 73 to 130 mm Hg) during norepinephrine infusion, V(mean) remained unchanged in 2 patients in the anterior cerebral artery, whereas it increased in the middle cerebral artery in all 7 patients. In the remaining patients, V(mean) increased approximately 25% in both the anterior and middle cerebral arteries. Thus, this study could only partially confirm the hypothesis that autoregulation is preserved in the brain regions supplied by the anterior cerebral artery in patients with FHF. Although the findings of this small study need to be further evaluated, one should consider that autoregulation may be impaired not only in the brain region supplied by the middle cerebral artery, but also in the area corresponding to the anterior cerebral artery.

Induced hypothermia in the management of cerebral oedema secondary to fulminant liver failure

The use of mild hypothermia in the management of blunt head trauma has been shown to significantly improve clinical outcomes. The use of moderate controlled hypothermia in the patient with severely raised intracranial pressure (ICP) secondary to fulminant hepatic failure (FHF) has similar potential benefits, but is not a widely accepted practice. We report a case where the use of hypothermia in the management of severely raised ICP both before and after liver transplantation was thought to effect a beneficial outcome.

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.

Coma and confusional states: emergency diagnosis and management

Coma and confusion signal a failure of brain function with many possible causes. Since many of the potential causes may quickly lead to death or severe disability, it is important to develop a focused and ordered approach to facilitate the rapid diagnosis and early institution of proper therapies. This requires an understanding of the localizing features of the neurologic examination and of the syndromes likely to cause coma and confusion, a predetermined plan for empiric therapies in certain cases of doubt when diagnostic confirmation will be delayed, and a careful consideration of cases when the diagnosis is not revealed by the initial neuroimaging, lumbar puncture, or EEG.

Effect of endotracheal suctioning on the intracerebral haemodynamics of patients in fulminant hepatic failure

Fulminant hepatic failure is a severe impairment of liver function in someone who has had previously normal liver function. The patients presenting to intensive therapy units have generally had a rapid deterioration which requires prompt intervention and treatment. The first part of this paper gives a detailed review of the aetiology, physiology and management of the disease process. Medical and nursing care of these patients is critical; any adverse intervention may affect outcome. A literature review and small study of the intervention of endotracheal suctioning and its effects on intracranial pressure and cerebral perfusion pressure is described.

Cerebral edema and intracranial pressure monitoring

With the wide acceptance of liver transplantation as a therapeutic alternative in fulminant hepatic failure (FHF), the successful management of patients with this syndrome has acquired a new urgency. Topping the list of medical problems is the development of brain swelling. Two decades after the recognition of its importance, brain edema and intracranial hypertension still constitute a major cause of death in these patients. In a more recent classification of FHF, brain edema was especially prominent in those subjects with "hyperacute failure," in whom a period of 7 days or less elapsed between the development of jaundice and encephalopathy. The goal of this review is to discuss two aspects of this clinical problem. On one hand, elucidation of its pathogenesis should lead to a more rational therapeutic approach; such an information would also be valuable to understand the relationship between hepatic encephalopathy and brain edema, a source of controversy. Studies of pathogenic mechanisms are difficult to perform in humans and animal models of FHF have proven valuable, as brain swelling can be detected with some regularity. On the other hand, an increasing array of techniques is now available in the intensive care setting to monitor patients with FHF. Of these, intracranial pressure monitoring has received the most critical attention. However, concerns with the risks of craniotomy and the need to acquire more dynamic information has led several groups to explore non-invasive methods that evaluate the consequences of intracranial hypertension. Their role, though potentially exciting, is still uncertain.