Assessment and management of cerebral edema and intracranial hypertension in acute liver failure

Viral hepatitis-induced acute liver failure

Viral hepatitis-induced acute liver failure (ALF) is a preventable cause for liver-related mortality worldwide. Viruses are the most common cause for ALF in developing nations in contrast to the west, where acetaminophen is largely responsible. Viruses may be hepatotropic or affect the liver secondary to a systemic infection. In tropical countries, infections such as leptospirosis, scrub typhus and malaria can mimic the symptoms of ALF. Differentiating these ALF mimics is crucial because they require etiology-specific therapy. Treatment of viral hepatitis-induced ALF is two-pronged and directed towards providing supportive care to prevent organ failures and antiviral drugs for some viruses. Liver transplantation (LT) is an effective modality for patients deteriorating despite adequate supportive care. Early referral and correct identification of patients who require a transplant are important. Liver support devices and plasma exchange have evolved into "bridging modalities" for LT. Preventive strategies such as hand hygiene, use of clean and potable water and inclusion of vaccines against viral hepatitis in the national program are simple yet very effective methods focusing on the preventive aspect of this disease.

A glimpse into multimodal neuromonitoring in acute liver failure: a case report

Introduction

Acute liver failure (ALF) is a rapidly progressing, life-threatening syndrome characterized by liver-related coagulopathy and hepatic encephalopathy (HE). Given that higher HE grades correlate with poorer outcomes, clinical management of ALF necessitates close neurological monitoring. The primary objective of this case report is to highlight the diagnostic value of utilizing multimodal neuromonitoring (MNM) in a patient suffering from ALF.

Case report

A 56-year-old male patient with a history of chronic alcoholism, without prior chronic liver disease, and recent acetaminophen use was admitted to the hospital due to fatigue and presenting with a mild flapping tremor. The primary hypothesis was an acute hepatic injury caused by acetaminophen intoxication. In the following hours, the patient's condition deteriorated, accompanied by neurological decline and rising ammonia levels. The patient's neurological status was closely monitored using MNM. Bilaterally altered pupillary light reflex assessed by decreasing in the Neurological Pupil Index values, using automated pupillometry, initially suggested severe brain oedema. However, ultrasound measurements of the optic nerve sheath diameter showed normal values in both eyes, P2/P1 noninvasive intracranial pressure waveform assessment was within normal ranges and the cerebral computed tomography-scan revealed no signs of cerebral swelling. Increased middle cerebral artery velocities measured by Transcranial Doppler and the initiation of electroencephalography monitoring yielded the presence of status epilepticus.

Discussion

The utilization of MNM facilitated a more comprehensive understanding of the mechanisms underlying the patient's clinical deterioration in the setting of HE. Nonetheless, future studies are needed to show feasibility and to yield valuable insights that can enhance the outcomes for patients with HE using such an approach. Given the absence of specific guidelines in this particular context, it is advisable for physicians to give further consideration to the incorporation of MNM in the management of unconscious patients with ALF.

Invasive Neuromonitoring Modalities in the Pediatric Population

Invasive neuromonitoring has become an important part of pediatric neurocritical care, as neuromonitoring devices provide objective data that can guide patient management in real time. New modalities continue to emerge, allowing clinicians to integrate data that reflect different aspects of cerebral function to optimize patient management. Currently, available common invasive neuromonitoring devices that have been studied in the pediatric population include the intracranial pressure monitor, brain tissue oxygenation monitor, jugular venous oximetry, cerebral microdialysis, and thermal diffusion flowmetry. In this review, we describe these neuromonitoring technologies, including their mechanisms of function, indications for use, advantages and disadvantages, and efficacy, in pediatric neurocritical care settings with respect to patient outcomes.

Transcranial Doppler Ultrasonography in Children With Acute Liver Failure and Severe Hepatic Encephalopathy

OBJECTIVES

To report our single-center use of transcranial Doppler (TCD) for noninvasive neuromonitoring in pediatric patients with acute liver failure (ALF).

DESIGN

Retrospective cohort from January 2016 to June 2019.

SETTING

PICU in Bicêtre Hospital, Assistance Publique- Hôpitaux de Paris (AP-HP), a national referral center for pediatric liver transplantation.

PATIENTS

Pediatric patients with severe ALF (prothrombin time < 30% and Hepatic Encephalopathy score ≥ 3), on continuous venovenous high-flow hemofiltration.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Ten children were identified, six were transplanted (1/6 died) and four were not (3/4 died). TCD was performed several times per patient and the evolution of cerebral perfusion parameters was followed. Of interest, zero of six patients who survived lost end-diastolic velocity (EDV), whereas four of four patients who died did (difference, 100%; 95% CI, 37-100%; χ 2 , 9; degrees of freedom, 1; p = 0.0027). We failed to identify an association between pulsatility index (PI) or EDV, and severity of hepatic encephalopathy.

CONCLUSIONS

TCD was a noninvasive and bedside available tool to detect and screen for presence of abnormal cerebral flow in children with ALF, according to age-related reference values. TCD detected reduced EDV and elevated PI in children with ALF awaiting transplant who died compared with those who survived.

Current concepts in acute liver failure

Acute liver failure (ALF) is a severe condition secondary to a myriad of causes associated with poor outcomes. The prompt diagnosis and identification of the aetiology allow the administration of specific treatments plus supportive strategies and to define the overall prognosis, the probability of developing complications and the need for liver transplantation. Pivotal issues are adequate monitoring and the institution of prophylactic strategies to reduce the risk of complications, such as progressive liver failure, cerebral oedema, renal failure, coagulopathies or infections. In this article, we review the main aspects of ALF, including the definition, diagnosis and complications. Also, we describe the standard-of-care strategies and recent advances in the treatment of ALF. Finally, we include our experience of care patients with ALF.

Astrocyte swelling in hepatic encephalopathy: molecular perspective of cytotoxic edema

Hepatic encephalopathy (HE) may occur in patients with liver failure. The most critical pathophysiologic mechanism of HE is cerebral edema following systemic hyperammonemia. The dysfunctional liver cannot eliminate circulatory ammonia, so its plasma and brain levels rise sharply. Astrocytes, the only cells that are responsible for ammonia detoxification in the brain, are dynamic cells with unique phenotypic properties that enable them to respond to small changes in their environment. Any pathological changes in astrocytes may cause neurological disturbances such as HE. Astrocyte swelling is the leading cause of cerebral edema, which may cause brain herniation and death by increasing intracranial pressure. Various factors may have a role in astrocyte swelling. However, the exact molecular mechanism of astrocyte swelling is not fully understood. This article discusses the possible mechanisms of astrocyte swelling which related to hyperammonia, including the possible roles of molecules like glutamine, lactate, aquaporin-4 water channel, 18 KDa translocator protein, glial fibrillary acidic protein, alanine, glutathione, toll-like receptor 4, epidermal growth factor receptor, glutamate, and manganese, as well as inflammation, oxidative stress, mitochondrial permeability transition, ATP depletion, and astrocyte senescence. All these agents and factors may be targeted in therapeutic approaches to HE.

[Multiple organ manifestations of liver failure in acute small bowel obstruction]

Modern surgical and intensive care achievements did not result decrease of mortality in patients with acute small bowel obstruction (ASBO). Direct cause of mortality in ASBO patients is peritonitis followed by multiple organ failure syndrome including acute failure of liver, kidneys, lungs and other organs. Publications devoted to the problem of acute liver failure and its complicationsare reviewed in the article. Mechanisms of pathogenesis and clinical manifestations of multiple organ failure syndrome in patients with acute small bowel obstruction are analyzed.

The Clinical Spectrum and Manifestations of Acute Liver Failure

Acute liver failure (ALF) is a rare life-threatening condition characterized by rapid progression and death. Causes vary according to geographic region, with acetaminophen and drug-induced ALF being the most common causes in the United States. Determining the cause aids in predicting the prognosis and the presentation of manifestations and guides providers to perform cause-specific management. At initial presentation, nonspecific symptoms are present but may progress to complications, including cerebral edema, infection, coagulopathy, renal failure, cardiopulmonary failure, and acid-base and/or metabolic disturbances. Although some cases of ALF resolve with conservative measures, liver transplantation is the ultimate treatment in many cases.

Acute Liver Failure

Acute liver failure (ALF) is a life-threatening condition of heterogeneous etiology. Outcomes are better with early recognition and prompt initiation of etiology-specific therapy, intensive care protocols, and liver transplantation (LT). Prognostic scoring systems include the King's College Criteria and Model for End-stage Liver Disease score. Cerebral edema and intracranial hypertension are reasons for high morbidity and mortality; hypertonic saline is suggested for patients with a high risk for developing intracranial hypertension, and when it does, mannitol is recommended as first-line therapy. Extracorporeal liver support system may serve as a bridge to LT and may increase LT-free survival in select cases.

Hyperammonemia: What Urea-lly Need to Know: Case Report of Severe Noncirrhotic Hyperammonemic Encephalopathy and Review of the Literature

Purpose. A 66-year-old man who presented with coma was found to have isolated severe hyperammonemia and diagnosed with a late-onset urea-cycle disorder. He was treated successfully and had full recovery. Methods. We report a novel case of noncirrhotic hyperammonemia and review the literature on this topic. Selected literature for review included English-language articles concerning hyperammonemia using the search terms “hyperammonemic encephalopathy”, “non-cirrhotic encephalopathy”, “hepatic encephalopathy”, “urea-cycle disorders”, “ornithine transcarbamylase (OTC) deficiency”, and “fulminant hepatic failure”. Results. A unique case of isolated hyperammonemia diagnosed as late-onset OTC deficiency is presented. Existing evidence about hyperammonemia is organized to address pathophysiology, clinical presentation, diagnosis, and treatment. The case report is discussed in context of the reviewed literature. Conclusion. Late-onset OTC deficiency presenting with severe hyperammonemic encephalopathy and extensive imaging correlate can be fully reversible if recognized promptly and treated aggressively.

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.

Continuous molecular adsorbent recirculating system treatment in 69 patients listed for liver transplantation

OBJECTIVE

The molecular adsorbent recirculating system (MARS) is used to purify blood from albumin-bound toxins in patients with liver failure. However, the application of MARS has not demonstrated improved survival in randomized clinical trials and the clinical utility has not been finally established. In our department, the use of MARS is now restricted to the most critically ill patients with acute or acute on chronic liver failure.

MATERIAL AND METHODS

Since 2005, we have treated 69 patients (30 males/39 females with median age of 49 years ranging from 1 months to 70 years) listed for liver transplantation (LT) with MARS. Median model of end-stage liver disease score in patients older than 12 years of age (n = 56) was 33 (interquartile range 26-39). The flow rate was 35-40 mL/kg/h and treatment kits were changed every 8-12 h. The patients were treated for a median of 27 h (range 1-144 h).

RESULTS

Fifty-six patients (81%) were transplanted. Nine died before they could be transplanted, and four patients recovered without transplantation. Forty-six (82%) of the transplanted patients were alive 30 days after transplantation. Ammonium decreased modestly from a median of 148 to 124 µM (p = 0.03) during MARS treatment. We detected worsening of coagulopathy with significant decreases in platelet count and fibrinogen concentrations, and increase in International Normalized Ratio. Phosphate and magnesium decreased significantly during MARS treatment.

CONCLUSION

Continuous MARS therapy may bridge liver failure patients to LT under close observation and treatment of coagulopathy and electrolyte disturbances.

Diagnosis and Management of Hepatic Encephalopathy in Fulminant Hepatic Failure

Hepatic encephalopathy (HE) is associated with cerebral edema (CE), increased intracranial pressure (ICP), and subsequent neurologic complications; it is the most important cause of morbidity and mortality in fulminant hepatic failure. The goal of therapy should be early diagnosis and treatment of HE with measures to reduce CE. A combination of clinical examination and diagnostic modalities can aid in prompt diagnosis. ICP monitoring and transcranial Doppler help diagnose and monitor response to treatment. Transfer to a transplant center and intensive care unit admission with airway management and reduction of CE with hypertonic saline, mannitol, hypothermia, and sedation are recommended as a bridge to liver transplantation.

Role of nuclear factor-erythroid 2-related factor 2 (Nrf2) in the transcriptional regulation of brain ABC transporters during acute acetaminophen (APAP) intoxication in mice

Changes in expression of liver ABC transporters have been described during acute APAP intoxication. However, the effect of APAP on brain ABC transporters is poorly understood. The aim of this study was to evaluate the effect of APAP on brain ABC transporters expression and the role of the oxidative stress sensor Nrf2. Male C57BL/6J mice were administered APAP (400mg/kg) for analysis of brain mRNA and protein expression of Mrp1-6, Bcrp and P-gp. The results show induction of P-gp, Mrp2 and Mrp4 proteins, with no changes in Bcrp, Mrp1 or Mrp5-6. The protein values were accompanied by corresponding changes in mRNA levels. Additionally, brain Nrf2 nuclear translocation and expression of two Nrf2 target genes,

NAD(P)H

quinone oxidoreductase 1 (Nqo1) and Hemoxygenase 1 (Ho-1), was evaluated at 6, 12 and 24h after APAP treatment. Nrf2 nuclear content increased by 58% at 12h after APAP along with significant increments in mRNA and protein expression of Nqo1 and Ho-1. Furthermore, APAP treated Nrf2 knockout mice did not increase mRNA or protein expression of Mrp2 and Mrp4 as observed in wildtypes. In contrast, P-gp induction by APAP was observed in both genotypes. In conclusion, acute APAP intoxication induces protein expression of brain P-gp, Mrp2 and Mrp4. This study also suggests that brain changes in Mrp2 and Mrp4 expression may be due to in situ Nrf2 activation by APAP, while P-gp induction is independent of Nrf2 function. The functional consequences of these changes in brain ABC transporters by APAP deserve further attention.

Temperature modulation with an esophageal heat transfer device - a pediatric swine model study

Background

An increasing number of conditions appear to benefit from control and modulation of temperature, but available techniques to control temperature often have limitations, particularly in smaller patients with high surface to mass ratios. We aimed to evaluate a new method of temperature modulation with an esophageal heat transfer device in a pediatric swine model, hypothesizing that clinically significant modulation in temperature (both increases and decreases of more than 1°C) would be possible.

Methods

Three female Yorkshire swine averaging 23 kg were anesthetized with inhalational isoflurane prior to placement of the esophageal device, which was powered by a commercially available heat exchanger. Swine temperature was measured rectally and cooling and warming were performed by selecting the appropriate external heat exchanger mode. Temperature was recorded over time in order to calculate rates of temperature change. Histopathology of esophageal tissue was performed after study completion.

Results

Average swine baseline temperature was 38.3°C. Swine #1 exhibited a cooling rate of 3.5°C/hr; however, passive cooling may have contributed to this rate. External warming blankets maintained thermal equilibrium in swine #2 and #3, demonstrating maximum temperature decrease of 1.7°C/hr. Warming rates averaged 0.29°C/hr. Histopathologic analysis of esophageal tissue showed no adverse effects.

Conclusions

An esophageal heat transfer device successfully modulated the temperature in a pediatric swine model. This approach to temperature modulation may offer a useful new modality to control temperature in conditions warranting temperature management (such as maintenance of normothermia, induction of hypothermia, fever control, or malignant hyperthermia).

Anesthetic management of labor and delivery in patients with elevated intracranial pressure

The anesthetic management of labor and delivery in patients with elevated intracranial pressure is complex. This review discusses the etiologies of diffuse and focal pathologies which lead to elevated intracranial pressure in pregnancy. The role of neuraxial and general anesthesia in the management of labor and delivery is also examined. Finally, a comprehensive review of strategies to minimize increases in intracranial pressure during general anesthesia for cesarean delivery is presented.

Review of anesthesia in liver transplantation

Liver transplantation (LT) is a well-accepted treatment modality of many end-stage liver diseases. The main issue in LT is the shortage of deceased donors to accommodate the needs of patients waiting for such transplants. Live donors have tremendously increased the pool of available liver grafts, especially in countries where deceased donors are not common. The main ethical concern of this procedure is the safety of healthy donors, who undergo a major abdominal surgery not for their own health, but to help cure others. The first part of the review concentrates on live donor selection, preanesthetic evaluation, and intraoperative anesthetic care for living liver donors. The second part reviews patient evaluation, intraoperative anesthesia monitoring, and fluid management of the recipient. This review provides up-to-date information to help improve the quality of anesthesia, and contribute to the success of LT and increase the long-term survival of the recipients.

GABA and 5-HT chitosan nanoparticles decrease striatal neuronal degeneration and motor deficits during liver injury

The metabolic alterations resulted from hepatic injury and cell loss lead to synaptic defects and neurodegeneration that undoubtedly contribute motor deficits. In the present study, GABA and 5-HT chitosan nanoparticles mediated liver cell proliferation influenced by growth factor and cytokines and neuronal survival in corpus striatum of partially hepatectomised rats was evaluated. Liver cell proliferation was initiated and progressed by the combined effect of increased expression of growth factor, insulin like growth factor-1 and decreased expressions of cytokines, tumor necrosis factor-α and Akt-1. This was confirmed by the extent of incorporation of thymidine analogue, BrdU, in the DNA of rapidly dividing cells. Inappropriate influx of compounds to corpus striatum resulting from incomplete metabolism elevated GABAB and 5-HT2A neurotransmissions compared to those treated with nanoparticles. This directly influenced cyclic AMP response element binding protein, glial cell derived neurotrophic factor and brain derived neurotrophic factor in the corpus striatum that facilitate neurogenesis, neuronal survival, development, differentiation and neuroprotection. Motor deficits due to liver injury followed striatal neuronal damage were scored by grid walk and rotarod studies, which confirmed the regain of motor activity by GABA and 5-HT chitosan nanoparticle treatment. The present study revealed the therapeutic significance of GABA and 5-HT chitosan nanoparticles in liver based diseases and related striatal neuronal damage that influenced by GABA and 5-HT.

Pathophysiology of cerebral oedema in acute liver failure

Cerebral oedema is a devastating consequence of acute liver failure (ALF) and may be associated with the development of intracranial hypertension and death. In ALF, some patients may develop cerebral oedema and increased intracranial pressure but progression to life-threatening intracranial hypertension is less frequent than previously described, complicating less than one third of cases who have proceeded to coma since the advent of improved clinical care. The rapid onset of encephalopathy may be dramatic with the development of asterixis, delirium, seizures and coma. Cytotoxic and vasogenic oedema mechanisms have been implicated with a preponderance of experimental data favouring a cytotoxic mechanism. Astrocyte swelling is the most consistent neuropathological finding in humans with ALF and ammonia plays a definitive role in the development of cytotoxic brain oedema. The mechanism(s) by which ammonia induces astrocyte swelling remains unclear but glutamine accumulation within astrocytes has led to the osmolyte hypothesis. Current evidence also supports an alternate ‘Trojan horse’ hypothesis, with glutamine as a carrier of ammonia into mitochondria, where its accumulation results in oxidative stress, energy failure and ultimately astrocyte swelling. Although a complete breakdown of the blood-brain barrier is not evident in human ALF, increased permeation to water and other small molecules such as ammonia has been demonstrated resulting from subtle alterations in the protein composition of paracellular tight junctions. At present, there is no fully efficacious therapy for cerebral oedema other than liver transplantation and this reflects our incomplete knowledge of the precise mechanisms underlying this process which remain largely unknown.