Therapeutic hypothermia for acute liver failure. Crit Care Med. 2009;37:S258-S264. [PMID: 19535956 DOI: 10.1097/ccm.0b013e3181aa5fb8]

Therapeutic management of ischemic stroke

Stroke is the third leading cause of years lost due to disability and the second-largest cause of mortality worldwide. Most occurrences of stroke are brought on by the sudden occlusion of an artery (ischemic stroke), but sometimes they are brought on by bleeding into brain tissue after a blood vessel has ruptured (hemorrhagic stroke). Alteplase is the only therapy the American Food and Drug Administration has approved for ischemic stroke under the thrombolysis category. Current views as well as relevant clinical research on the diagnosis, assessment, and management of stroke are reviewed to suggest appropriate treatment strategies. We searched PubMed and Google Scholar for the available therapeutic regimes in the past, present, and future. With the advent of endovascular therapy in 2015 and intravenous thrombolysis in 1995, the therapeutic options for ischemic stroke have expanded significantly. A novel approach such as vagus nerve stimulation could be life-changing for many stroke patients. Therapeutic hypothermia, the process of cooling the body or brain to preserve organ integrity, is one of the most potent neuroprotectants in both clinical and preclinical contexts. The rapid intervention has been linked to more favorable clinical results. This study focuses on the pathogenesis of stroke, as well as its recent advancements, future prospects, and potential therapeutic targets in stroke therapy.

Therapeutic Hypothermia in Treating Glioblastoma: A Review

Glioblastoma (GBM) is the most commonly occurring of all malignant central nervous system (CNS) tumors in adults. Considering the low median survival of only ∼15 months and poor prognosis in GBM patients, despite surgical resection with adjuvant radiation and chemotherapy, it is vital to seek brand new and innovative treatment in combination with already existing methods. Hypothermia participates in many metabolic pathways, inflammatory responses, and apoptotic processes, while also promoting the integrity of neurons. Following the successful application of therapeutic hypothermia across a spectrum of disorders such as traumatic CNS injury, cardiac arrest, and epilepsy, several clinical trials have set to evaluate the potency of hypothermia in treating a variety of cancers, including breast and ovaries cancer. In regard to primary neoplasms and more specifically, GBM, hypothermia has recently shown promising results as an auxiliary treatment, reinforcing chemotherapy's efficacy. In this review, we discuss the recent advances in utilizing hypothermia as treatment for GBM and other cancers.

Live donor liver transplantation for pediatric acute liver failure: challenges and outcomes

OBJECTIVE

This study aimed at studying the challenges and outcomes of live-donor liver transplantation (LDLT) for pediatric acute liver failure (PALF).

STUDY DESIGN

A total of 315 patients with PALF were treated over a period of 11 years. 42 underwent LT (41 LDLT and one DDLT), constituting 38% (41/110) of all pediatric transplants during this duration. The outcomes of LDLT for PALF were analyzed.

RESULTS

All the 41 children who underwent LT met the Kings College criteria (KCC). The etiology was indeterminate in 46.3% (n = 19) children. 75.6% (n = 31) were on mechanical ventilation for grade 3/4 hepatic encephalopathy. There was presence of cerebral edema on a computed tomography scan of the brain in 50% of the children. One-third of our children required hemodynamic support with vasopressors. Systemic inflammatory response syndrome and sepsis were observed in 46.3% and 41.4% of patients, respectively. Post-LDLT 1- and 5-yr patient and graft survival were 75.6% and 70.9%, respectively. The survival in children satisfying KCC but did not undergo LT was 24% (38/161). Vascular and biliary complication rates were 2.4% and 4.8%, respectively. No graft loss occurred because of acute rejection. In multivariate analysis, pre-LT culture positivity and cerebral edema, persistence of brain edema after transplantation, and resultant pulmonary complications were significantly associated with post-LT death. Thirteen (32%) children who underwent plasmapheresis prior to LT had better post-LT neurological recovery, as evidenced by early extubation.

CONCLUSION

LDLT for PALF is lifesaving and provides a unique opportunity to time transplantation. Good long-term survival can be achieved, despite the majority of patients presenting late for transplantation. Early referral and better selection can save more lives through timely transplantation.

The forgotten art of cold therapeutic properties in cancer: A comprehensive historical guide

Cold therapy has been used for centuries, from Julius Caesar to Mohandas Gandhi, as a potent therapeutic approach. However, it has been largely forgotten in modern medicine. This review explores the history of cold therapy and its potential application as a therapeutic strategy against various diseases, including cancer. We examine the different techniques of cold exposure and the use of other therapeutical approaches, such as cryoablation, cryotherapy, cryoimmunotherapy, cryothalectomy, and delivery of cryogen agents. While clinical trials using cold therapy for cancer treatment are still limited, recent research shows promising results in experimental animal cancer models. This area of research is becoming increasingly significant and warrants further investigation.

General Critical Care, Temperature Control, and End-of-Life Decision Making in Patients Resuscitated from Cardiac Arrest

Cardiac arrest affects millions of people per year worldwide. Although advances in cardiopulmonary resuscitation and intensive care have improved outcomes over time, neurologic impairment and multiple organ dysfunction continue to be associated with a high mortality rate. The pathophysiologic mechanisms underlying the post-resuscitation disease are complex, and a coordinated, evidence-based approach to post-resuscitation care has significant potential to improve survival. Critical care management of patients resuscitated from cardiac arrest focuses on the identification and treatment of the underlying cause(s), hemodynamic and respiratory support, organ protection, and active temperature control. This review provides a state-of-the-art appraisal of critical care management of the post-cardiac arrest patient.

A mechanistic view of the use of cold temperature in the treatment of cancer

In their latest article, Seki and colleagues investigate the potential role of cold as a therapeutical option to treat various cancer types, including even clinically untreatable cancers such as pancreatic cancers. The authors suggest that cold exposure may have a tumor-suppressive effect mediated by the activation of brown adipose tissue (BAT), in charge of dissipating heat through non-shivering thermogenesis. In this regard, circulating blood glucose is decreased, restricting the tumor glucose uptake, which is redistributed, favoring BAT uptake to fuel thermogenesis.¹.

Issues of intensive care and liver transplantation tactics in fulminant liver failure

Fulminant liver failure is usually characterized as severe acute liver injury with encephalopathy and synthetic dysfunction (international normalized ratio [INR] ≥1.5) in a patient without cirrhosis or previous liver disease. Management of patients with acute liver failure includes ensuring that the patient is cared for appropriately, monitoring for worsening liver failure, managing complications, and providing nutritional support. Patients with acute liver failure should be treated at a liver transplant center whenever possible. Serial laboratory tests are used to monitor the course of a patient's liver failure and to monitor for complications. It is necessary to monitor the level of aminotransferases and bilirubin in serum daily. More frequent monitoring (three to four times a day) of blood coagulation parameters, complete blood count, metabolic panels, and arterial blood gases should be performed. For some causes of acute liver failure, such as acetaminophen intoxication, treatment directed at the underlying cause may prevent the need for liver transplantation and reduce mortality. Lactulose has not been shown to improve overall outcomes, and it can lead to intestinal distention, which can lead to technical difficulties during liver transplantation. Early in acute liver failure, signs and symptoms of cerebral edema may be absent or difficult to detect. Complications of cerebral edema include increased intracranial pressure and herniation of the brain stem. General measures to prevent increased intracranial pressure include minimizing stimulation, maintaining an appropriate fluid balance, and elevating the head of the patient's bed. For patients at high risk of developing cerebral edema, we also offer hypertonic saline prophylaxis (3%) with a target serum sodium level of 145 to 155 mEq/L (level 2C). High-risk patients include patients with grade IV encephalopathy, high ammonia levels (>150 µmol/L), or acute renal failure, and patients requiring vasopressor support. Approximately 40 % of patients with acute liver failure recover spontaneously with supportive care. Predictive models have been developed to help identify patients who are unlikely to recover spontaneously, as the decision to undergo liver transplant depends in part on the likelihood of spontaneous recovery of the liver. However, among those who receive a transplant, the one-year survival rate exceeds 80 %, making this treatment the treatment of choice in this difficult patient population.

Consensus recommendations on therapeutic hypothermia after minimally invasive intracerebral hemorrhage evacuation from the hypothermia for intracerebral hemorrhage (HICH) working group

Background and purpose

Therapeutic hypothermia (TH), or targeted temperature management (TTM), is a classic treatment option for reducing inflammation and potentially other destructive processes across a wide range of pathologies, and has been successfully used in numerous disease states. The ability for TH to improve neurological outcomes seems promising for inflammatory injuries but has yet to demonstrate clinical benefit in the intracerebral hemorrhage (ICH) patient population. Minimally invasive ICH evacuation also presents a promising option for ICH treatment with strong preclinical data but has yet to demonstrate functional improvement in large randomized trials. The biochemical mechanisms of action of ICH evacuation and TH appear to be synergistic, and thus combining hematoma evacuation with cooling therapy could provide synergistic benefits. The purpose of this working group was to develop consensus recommendations on optimal clinical trial design and outcomes for the use of therapeutic hypothermia in ICH in conjunction with minimally invasive ICH evacuation.

Methods

An international panel of experts on the intersection of critical-care TH and ICH was convened to analyze available evidence and form a consensus on critical elements of a focal cooling protocol and clinical trial design. Three focused sessions and three full-group meetings were held virtually from December 2020 to February 2021. Each meeting focused on a specific subtopic, allowing for guided, open discussion.

Results

These recommendations detail key elements of a clinical cooling protocol and an outline for the roll-out of clinical trials to test and validate the use of TH in conjunction with hematoma evacuation as well as late-stage protocols to improve the cooling approach. The combined use of systemic normothermia and localized moderate (33.5°C) hypothermia was identified as the most promising treatment strategy.

Conclusions

These recommendations provide a general outline for the use of TH after minimally invasive ICH evacuation. More research is needed to further refine the use and combination of these promising treatment paradigms for this patient population.

Management of Acute Liver Failure: Update 2022

Abbreviated pathogenesis and clinical course of the acute liver failure syndrome. The pathogenesis and clinical course of the syndrome of acute liver failure (ALF) differs depending upon the etiology of the primary liver injury. In turn, the severity of the liver injury and resulting synthetic failure is often the primary determinant of whether a patient is referred for emergency liver transplantation. Injuries by viral etiologies trigger the innate immune system via pathogen-associated molecular patterns (PAMPs), while toxin-induced (and presumably ischemia-induced) injuries do so via damage-associated molecular patterns (DAMPs). The course of the clinical syndrome further depends upon the relative intensity and composition of cytokine release, resulting in an early proinflammatory phenotype (SIRS) and later compensatory anti-inflammatory response phenotype (CARS). The outcomes of overwhelming immune activation are the systemic (extrahepatic) features of ALF (cardiovascular collapse, cerebral edema, acute kidney injury, respiratory failure, sepsis) which ultimately determine the likelihood of death.Acute liver failure (ALF) continues to carry a high risk of mortality or the need for transplantation despite recent improvements in overall outcomes over the past two decades. Optimal management begins with identifying that liver failure is indeed present and its etiology, since outcomes and the need for transplantation vary widely across the different etiologies. Most causes of ALF can be divided into hyperacute (ischemia and acetaminophen) and subacute types (other etiologies), based on time of evolution of signs and symptoms of liver failure; the former evolve in 3 to 4 days and the latter typically in 2 to 4 weeks. Both involve intense release of cytokines and hepatocellular contents into the circulation with multiorgan effects/consequences.Management involves optimizing fluid balance and cardiovascular support, including the use of continuous renal replacement therapy, vasopressors, and pulmonary ventilation. Early evaluation for liver transplantation is advised particularly for acetaminophen toxicity, which evolves so rapidly that delay is likely to lead to death.Vasopressor support, high-grade hepatic encephalopathy, and unfavorable (subacute) etiologies heighten the need for urgent listing for liver transplantation. Prognostic scores such as Kings Criteria, Model for End-Stage Liver Disease, and the Acute Liver Failure Group prognostic index take these features into account and provide reasonable but imperfect predictive accuracy. Future treatments may include liver support devices and/or agents that improve hepatocyte regeneration.

Dysregulation of Astrocytic Glutamine Transport in Acute Hyperammonemic Brain Edema

Acute liver failure (ALF) impairs ammonia clearance from blood, which gives rise to acute hyperammonemia and increased ammonia accumulation in the brain. Since in brain glutamine synthesis is the only route of ammonia detoxification, hyperammonemia is as a rule associated with increased brain glutamine content (glutaminosis) which correlates with and contributes along with ammonia itself to hyperammonemic brain edema-associated with ALF. This review focuses on the effects of hyperammonemia on the two glutamine carriers located in the astrocytic membrane: Slc38a3 (SN1, SNAT3) and Slc7a6 (y + LAT2). We emphasize the contribution of the dysfunction of either of the two carriers to glutaminosis- related aspects of brain edema: retention of osmotically obligated water (Slc38a3) and induction of oxidative/nitrosative stress (Slc7a6). The changes in glutamine transport link glutaminosis- evoked mitochondrial dysfunction to oxidative-nitrosative stress as formulated in the “Trojan Horse” hypothesis.

Cheap and simple, could it get even cooler? Mild hypothermia and COVID-19

Purpose

The pathophysiology theories of COVID-19 attach the injury of target organs to faulty immune responses and occasionally hyper-inflammation. The damage frequently extends beyond the respiratory system, accompanying cardiovascular, renal, central nervous system, and/or coagulation derangements. Tumor necrosis factor-α (TNF-α) and interleukins (IL)-1 and − 6 suppression may improve outcomes, as experimentally shown. Targeted therapies have been proposed, but mild therapeutic hypothermia—a more multifaceted approach—could be suitable.

Findings

According to evidence derived from previous applications, therapeutic hypothermia diminishes the release of IL-1, IL-6, and TNF-α in serum and at the tissue level. PaCO2 is reduced and the PaO2/FiO2 ratio is increased, possibly lasting after rewarming. Cooling might mitigate both ventilator and infectious-induced lung injury, and suppress microthrombi development, enhancing V/Q mismatch. Improvements in microhemodynamics and tissue O2 diffusion, along with the ischemia-tolerance heightening of tissues, could be reached. Arrhythmia incidence diminishes. Moreover, hypothermia may address the coagulopathy, promoting normalization of both hypo- and hyper-coagulability patterns, which are apparently sustained after a return to normothermia.

Conclusions

As per prior therapeutic hypothermia literature, the benefits regarding inflammatory response and organic damage might be seen. Following the safety-cornerstones of the technique, the overall infection rate and infection-related mortality are not expected to rise, and increased viral replication does not seem to be a concern. Therefore, the possibility of a low cost and widely available therapy being capable of improving COVID-19 outcomes deserves further study.

Indian National Association for the Study of Liver Consensus Statement on Acute Liver Failure (Part-2): Management of Acute Liver Failure

Acute liver failure (ALF) is not an uncommon complication of a common disease such as acute hepatitis. Viral hepatitis followed by antituberculosis drug-induced hepatotoxicity are the commonest causes of ALF in India. Clinically, such patients present with appearance of jaundice, encephalopathy, and coagulopathy. Hepatic encephalopathy (HE) and cerebral edema are central and most important clinical event in the course of ALF, followed by superadded infections, and determine the outcome in these patients. The pathogenesis of encephalopathy and cerebral edema in ALF is unique and multifactorial. Ammonia plays a crucial role in the pathogenesis, and several therapies aim to correct this abnormality. The role of newer ammonia-lowering agents is still evolving. These patients are best managed at a tertiary care hospital with facility for liver transplantation (LT). Aggressive intensive medical management has been documented to salvage a substantial proportion of patients. In those with poor prognostic factors, LT is the only effective therapy that has been shown to improve survival. However, recognizing suitable patients with poor prognosis has remained a challenge. Close monitoring, early identification and treatment of complications, and couseling for transplant form the first-line approach to manage such patients. Recent research shows that use of dynamic prognostic models is better for selecting patients undergoing liver transplantation and timely transplant can save life of patients with ALF with poor prognostic factors.

Indian National Association for the Study of the Liver Consensus Statement on Acute Liver Failure (Part 1): Epidemiology, Pathogenesis, Presentation and Prognosis

Acute liver failure (ALF) is an infrequent, unpredictable, potentially fatal complication of acute liver injury (ALI) consequent to varied etiologies. Etiologies of ALF as reported in the literature have regional differences, which affects the clinical presentation and natural course. In this part of the consensus article designed to reflect the clinical practices in India, disease burden, epidemiology, clinical presentation, monitoring, and prognostication have been discussed. In India, viral hepatitis is the most frequent cause of ALF, with drug-induced hepatitis due to antituberculosis drugs being the second most frequent cause. The clinical presentation of ALF is characterized by jaundice, coagulopathy, and encephalopathy. It is important to differentiate ALF from other causes of liver failure, including acute on chronic liver failure, subacute liver failure, as well as certain tropical infections which can mimic this presentation. The disease often has a fulminant clinical course with high short-term mortality. Death is usually attributable to cerebral complications, infections, and resultant multiorgan failure. Timely liver transplantation (LT) can change the outcome, and hence, it is vital to provide intensive care to patients until LT can be arranged. It is equally important to assess prognosis to select patients who are suitable for LT. Several prognostic scores have been proposed, and their comparisons show that indigenously developed dynamic scores have an edge over scores described from the Western world. Management of ALF will be described in part 2 of this document.

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.

State-of-the-art considerations in post-arrest care

Cardiac arrest has a high rate of morbidity and mortality. Several advances in post-cardiac arrest management can improve outcome, but are time-dependent, placing the emergency physician in a critical role to both recognize the need for and initiate therapy. We present a novel perspective of both the workup and therapeutic interventions geared toward the emergency physician during the first few hours of care. We describe how the immediate care of a post-cardiac arrest patient is resource intensive and requires simultaneous evaluation for the underlying cause and intensive management to prevent further end organ damage, particularly of the central nervous system. The goal of the initial focused assessment is to rapidly determine if any reversible causes of cardiac arrest are present and to intervene when possible. Interventions performed in this acute period are aimed at preventing additional brain injury through optimizing hemodynamics, providing ventilatory support, and by using therapeutic hypothermia when indicated. After the initial phase of care, disposition is guided by available resources and the clinician's judgment. Transfer to a specialized cardiac arrest center is prudent in centers that do not have significant support or experience in the care of these patients.

Acute Liver Failure Induces Glial Reactivity, Oxidative Stress and Impairs Brain Energy Metabolism in Rats

Acute liver failure (ALF) implies a severe and rapid liver dysfunction that leads to impaired liver metabolism and hepatic encephalopathy (HE). Recent studies have suggested that several brain alterations such as astrocytic dysfunction and energy metabolism impairment may synergistically interact, playing a role in the development of HE. The purpose of the present study is to investigate early alterations in redox status, energy metabolism and astrocytic reactivity of rats submitted to ALF. Adult male Wistar rats were submitted either to subtotal hepatectomy (92% of liver mass) or sham operation to induce ALF. Twenty-four hours after the surgery, animals with ALF presented higher plasmatic levels of ammonia, lactate, ALT and AST and lower levels of glucose than the animals in the sham group. Animals with ALF presented several astrocytic morphological alterations indicating astrocytic reactivity. The ALF group also presented higher mitochondrial oxygen consumption, higher enzymatic activity and higher ATP levels in the brain (frontoparietal cortex). Moreover, ALF induced an increase in glutamate oxidation concomitant with a decrease in glucose and lactate oxidation. The increase in brain energy metabolism caused by astrocytic reactivity resulted in augmented levels of reactive oxygen species (ROS) and Poly [ADP-ribose] polymerase 1 (PARP1) and a decreased activity of the enzymes superoxide dismutase and glutathione peroxidase (GSH-Px). These findings suggest that in the early stages of ALF the brain presents a hypermetabolic state, oxidative stress and astrocytic reactivity, which could be in part sustained by an increase in mitochondrial oxidation of glutamate.

Effect of Therapeutic Hypothermia on Liver Enzymes in Patients With Stroke

Introduction:

A promising strategy that can lead to longer brain cell survival after an acute stroke is therapeutic hypothermia. It represents a controlled decrease in body temperature for therapeutic reasons. It is increasingly represented as a therapeutic option and is one of the most challenging treatments that improves neurological recovery and treatment outcome in patients with acute stroke.

Aim:

To examine the effect of therapeutic hypothermia on liver enzymes in patients with diagnosis of stroke.

Methods:

A total of 101 patients diagnosed with acute stroke were treated. The first group (n=40) were treated with conventional treatment and therapeutic hypothermia, while the second group (n=61) only with conventional treatment. Cooling of the body to a target body temperature of 34°C to 35°C was performed for up to 24 hours. Outcome (survival or death) of treatment was monitored, degree of disability was determined by National Institutes of Health Stroke Scale (NIHSS) and assessment of consciousness using the Glasgow Coma Scale (GCS). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) values were taken at admission, after 24 hours, and were monitored upon discharge.

Results:

There was a significant difference in AST values at admission relative to disease outcome (p = 0.002), as well as for ALT (p = 0.008). In patients treated with therapeutic hypothermia, mean AST values decreased after 24 hours (32.50 to 31.00 IU/mL) as well as ALT values (27.50 to 26.50 IU/mL), without statistical significance. In the group of subjects who survived with sequela, AST values correlated with GCS (rho = -0.489; p = 0.002) and NIHSS (rho = 0.492; p = 0.003), ALT values correlated with GCS (rho = -0.356; p = 0.03) but not with NIHSS.

Conclusion:

AST and ALT values at admission correlate with the severity of the clinical picture. Therapeutic hypothermia is hepatoprotective and lowers AST and ALT values.

From systemic to selective brain cooling - Methods in review

Therapeutic hypothermia (TH) remains one of the few proven neuroprotective modalities available in clinical practice today. Although targeting lower temperatures during TH seems to benefit ischemic brain cells, systemic side effects associated with global hypothermia limit its clinical applicability. Therefore, the ability to selectively reduce the temperature of the brain while minimally impacting core temperature allows for maximizing neurological benefit over systemic complications. In that scenario, selective brain cooling (SBC) has emerged as a promising modality of TH. In this report, we reviewed the general concepts of TH, from systemic to selective brain hypothermia, and explored the different cooling strategies and respective evidence, including preclinical and clinical data. SBC has been investigated in different animal models with promising results, wherein organ-specific, rapid, and deep target brain temperature managements stand out as major advantages over systemic TH. Nevertheless, procedure-related complications and adverse events still remain a concern, limiting clinical translation. Different invasive and noninvasive methods for SBC have been clinically investigated with variable results, and although adverse effects were still reported in some studies, therapies rendered overall safe profiles. Further study is needed to define the optimal technique, timing of initiation, rate and length of cooling as well as target temperature and rewarming protocols for different indications.

Acute liver failure

Acute liver failure is a rare and severe consequence of abrupt hepatocyte injury, and can evolve over days or weeks to a lethal outcome. A variety of insults to liver cells result in a consistent pattern of rapid-onset elevation of aminotransferases, altered mentation, and disturbed coagulation. The absence of existing liver disease distinguishes acute liver failure from decompensated cirrhosis or acute-on-chronic liver failure. Causes of acute liver failure include paracetamol toxicity, hepatic ischaemia, viral and autoimmune hepatitis, and drug-induced liver injury from prescription drugs, and herbal and dietary supplements. Diagnosis requires careful review of medications taken, and serological testing for possible viral exposure. Because of its rarity, acute liver failure has not been studied in large, randomised trials, and most treatment recommendations represent expert opinion. Improvements in management have resulted in lower mortality, although liver transplantation, used in nearly 30% of patients with acute liver failure, still provides a life-saving alternative to medical management.

PPARα-Mediated Positive-Feedback Loop Contributes to Cold Exposure Memory

Fluctuations in food availability and shifts in temperature are typical environmental changes experienced by animals. These environmental shifts sometimes portend more severe changes; e.g., chilly north winds precede the onset of winter. Such telltale signs may be indicators for animals to prepare for such a shift. Here we show that HEK293A cells, cultured under starvation conditions, can “memorize” a short exposure to cold temperature (15 °C), which was evidenced by their higher survival rate compared to cells continuously grown at 37 °C. We refer to this phenomenon as “cold adaptation”. The cold-exposed cells retained high ATP levels, and addition of etomoxir, a fatty acid oxidation inhibitor, abrogated the enhanced cell survival. In our standard protocol, cold adaptation required linoleic acid (LA) supplementation along with the activity of Δ-6-desaturase (D6D), a key enzyme in LA metabolism. Moreover, supplementation with the LA metabolite arachidonic acid (AA), which is a high-affinity agonist of peroxisome proliferator-activated receptor-alpha (PPARα), was able to underpin the cold adaptation, even in the presence of a D6D inhibitor. Cold exposure with added LA or AA prompted a surge in PPARα levels, followed by the induction of D6D expression; addition of a PPARα antagonist or a D6D inhibitor abrogated both their expression, and reduced cell survival to control levels. We also found that the brief cold exposure transiently prevents PPARα degradation by inhibiting the ubiquitin proteasome system, and starvation contributes to the enhancement of PPARα activity by inhibiting mTORC1. Our results reveal an innate adaptive positive-feedback mechanism with a PPARα-D6D-AA axis that is triggered by a brief cold exposure in cells. “Cold adaptation” could have evolved to increase strength and resilience against imminent extreme cold temperatures.

A case of chronic hepatitis B merged with acute fatty liver of pregnancy with severe coagulopathy

Background

Acute fatty liver of pregnancy (AFLP) is a life-threatening disorder, and its relevance to viral hepatitis B (HB) remains unknown. This case presents an initial experience of treating a patient with HB progressing to AFLP throughout pregnancy; anesthesiologists should also recognize its clinical feature for perioperative management.

Case presentation

A 28-year-old parturient was diagnosed as chronic HB (CHB) at 21 weeks gestation. Liver and kidney dysfunction appeared rapidly at 34 weeks gestation, suspected as acute exacerbation of either CHB or AFLP. Emergency cesarean section was carried out, after which maternal disseminated intravascular coagulation and hypothermia persisted. With multidisciplinary management, the patient and infant were discharged on postpartum days 64 and 12, respectively.

Conclusions

Active CHB develops into AFLP. Antiviral therapy should be considered for parturient patients with CHB, particularly for those with high viral load. The most favorable outcome is prompt and accurate diagnosis to establish suitable termination method.

Acute liver failure in two dogs following ingestion of cheese tree (Glochidion ferdinandi) roots

OBJECTIVE

To describe the management and resolution of acute liver failure (ALF) in two dogs following ingestion of cheese tree (Glochidion ferdinandi) roots.

CASE SUMMARIES

A 2-year-old male entire Bullmastiff and a 5-year-old female neutered German Shepherd dog were presented for acute-onset lethargy and vomiting after chewing on tree roots of a cheese tree. Both dogs developed clinical abnormalities consistent with ALF, including hepatic encephalopathy, marked increase in alanine aminotransferase activity and bilirubin concentration, and prolonged coagulation times. Treatment included administration of intravenous fluids, hepatoprotectants, vitamin K₁ , antibiotics, lactulose, antacids, antiemetics, and multiple fresh frozen plasma transfusions. Follow-up examinations performed 30 days after initial presentation revealed the dogs to be clinically healthy with serum biochemical and coagulation profiles within reference intervals.

NEW OR UNIQUE INFORMATION

This is the first report describing ALF in two dogs following ingestion of cheese tree (G. ferdinandi) roots. In this clinical setting, despite a poor prognosis, survival and recovery of adequate liver function were possible with medical management.

Medical Management of Acute Liver Failure

Pediatric acute liver failure is a rapidly progressive, life-threatening, and devastating illness in children without preexisting liver disease. Due to the rarity and heterogeneity of this syndrome, there is a significant lack of data to guide evaluation and management of this disease. Most of our practice is extrapolated from adult literature and guidelines. This leads to significant controversies in medical management of acute liver failure in children. With advances in critical care, there has been a tremendous improvement in outcomes with decreased morbidity and mortality; however, there is a dire need for more research in this field. This chapter discusses challenges as well as controversies in diagnostic evaluation and management of this rare but potentially fatal disease. Latest developments in supportive care of liver failure, including advances in the area of liver support systems, are also discussed.

Fatal neurological complication after liver transplantation in acute hepatic failure patient with hepatic encephalopathy

Liver transplantation is a current definitive treatment for those with end-stage liver disease. Hepatic encephalopathy is a common complication of hepatic failure, which can be improved and aggravated by various causes. It is important to differentiate hepatic encephalopathy from other diseases causing brain dysfunction such as cerebral hemorrhage, which is also related to high mortality after liver transplant surgery. A 37-year-old patient was presented with acute liver failure and high ammonia levels and seizure-like symptoms. Computed tomography (CT) of his brain showed mild brain atrophy, regarded as a symptom of hepatic encephalopathy, and treated to decrease blood ammonia level. Deceased donor liver transplantation was performed and liver function and ammonia level normalized after surgery, but the patient showed symptoms of involuntary muscle contraction and showed loss of pupil reflex and fixation without recovery of consciousness. Brain CT showed brain edema and bilateral cerebral infarction, and the patient died after a few days. The purpose of this case report is to emphasize the importance of preoperative neurological evaluation, careful transplantation decision, and proper perioperative management of liver transplantation in patients with acute hepatic encephalopathy.

Management of Acute Liver Failure: A Pediatric Perspective

Purpose of Review

Pediatric acute liver failure is a rare, complex, rapidly progressing, and life-threatening illness. Majority of pediatric acute liver failures have unknown etiology. This review intends to discuss the current literature on the challenging aspects of management of acute liver failure.

Recent Findings

Collaborative multidisciplinary approach for management of patients with pediatric acute liver failure with upfront involvement of transplant hepatologist and critical care specialists can improve outcomes of this fatal disease. Extensive but systematic diagnostic evaluation can help to identify etiology and guide management. Early referral to a transplant center with prompt liver transplant, if indicated, can lead to improved survival in these patients.

Summary

Prompt identification and aggressive management of pediatric acute liver failure and related comorbidities can lead to increased transplant-free survival and improved post-transplant outcomes, thus decreasing mortality and morbidity associated with this potential fatal condition.

Neuroprotective assessment of prolonged local hypothermia post contusive spinal cord injury in rodent model

BACKGROUND CONTEXT

Although general hypothermia is recognized as a clinically applicable neuroprotective intervention, acute moderate local hypothermia post contusive spinal cord injury (SCI) is being considered a more effective approach. Previously, we have investigated the feasibility and safety of inducing prolonged local hypothermia in the central nervous system of a rodent model.

PURPOSE

Here, we aimed to verify the efficacy and neuroprotective effects of 5 and 8 hours of local moderate hypothermia (30±0.5°C) induced 2 hours after moderate thoracic contusive SCI in rats.

STUDY DESIGN

Rats were induced with moderate SCI (12.5 mm) at its T8 section. Local hypothermia (30±0.5°C) was induced 2 hours after injury induction with an M-shaped copper tube with flow of cold water (12°C), from the T6 to the T10 region. Experiment groups were divided into 5-hour and 8-hour hypothermia treatment groups, respectively, whereas the normothermia control group underwent no hypothermia treatment.

METHODS

The neuroprotective effects were assessed through objective weekly somatosensory evoked potential (SSEP) and motor behavior (basso, beattie and bresnahan Basso, Beattie and Bresnahan (BBB) scoring) monitoring. Histology on spinal cord was performed until at the end of day 56. All authors declared no conflict of interest. This work was supported by the Singapore Institute for Neurotechnology Seed Fund (R-175-000-121-733), National University of Singapore, Ministry of Education, Tier 1 (R-172-000-414-112.).

RESULTS

Our results show significant SSEP amplitudes recovery in local hypothermia groups starting from day 14 post-injury onward for the 8-hour treatment group, which persisted up to days 28 and 42, whereas the 5-hour group showed significant improvement only at day 42. The functional improvement plateaued after day 42 as compared with control group of SCI with normothermia. This was supported by both 5-hour and 8-hour improvement in locomotion as measured by BBB scores. Local hypothermia also observed insignificant changes in its SSEP latency, as compared with the control. In addition, 5- and 8-hour hypothermia rats' spinal cord showed higher percentage of parenchyma preservation.

CONCLUSIONS

Early local moderate hypothermia can be induced for extended periods of time post SCI in the rodent model. Such intervention improves functional electrophysiological outcome and motor behavior recovery for a long time, lasting until 8 weeks.

Perioperative Care of the Liver Transplant Patient

With the evolution of surgical and anesthetic techniques, liver transplantation has become "routine," allowing for modifications of practice to decrease perioperative complications and costs. There is debate over the necessity for intensive care unit admission for patients with satisfactory preoperative status and a smooth intraoperative course. Postoperative care is made easier when the liver graft performs optimally. Assessment of graft function, vigilance for complications after the major surgical insult, and optimization of multiple systems affected by liver disease are essential aspects of postoperative care. The intensivist plays a vital role in an integrated multidisciplinary transplant team.

Intensive Care Management of Pediatric Acute Liver Failure

Pediatric acute liver failure is rare but life-threatening illness that occurs in children without preexisting liver disease. The rarity of the disease, along with its severity and heterogeneity, presents unique clinical challenges to the physicians providing care for pediatric patients with acute liver failure. In this review, practical clinical approaches to the care of critically ill children with acute liver failure are discussed with an organ system-specific approach. The underlying pathophysiological processes, major areas of uncertainty, and approaches to the critical care management of pediatric acute liver failure are also reviewed.

A multicentre randomized controlled trial of moderate hypothermia to prevent intracranial hypertension in acute liver failure

BACKGROUND & AIMS

Animal models and human case series of acute liver failure (ALF) suggest moderate hypothermia (MH) to have protective effects against cerebral oedema (CO) development and intracranial hypertension (ICH). However, the optimum temperature for patient management is unknown. In a prospective randomized controlled trial we investigated if maintenance of MH prevented development of ICH in ALF patients at high risk of the complication.

METHODS

Patients with ALF, high-grade encephalopathy and intracranial pressure (ICP) monitoring in specialist intensive care units were randomized by sealed envelope to targeted temperature management (TTM) groups of 34°C (MH) or 36°C (control) for a period of 72h. Investigators were not blinded to group assignment. The primary outcome was a sustained elevation in ICP >25mmHg, with secondary outcomes the occurrence of predefined serious adverse effects, magnitude of ICP elevations and cerebral and all-cause hospital mortality (with or without transplantation).

RESULTS

Forty-six patients were randomized, of whom forty-three were studied. There was no significant difference between the TTM groups in the primary outcome during the study period (35% vs. 27%, p=0.56), for the MH (n=17) or control (n=26) groups respectively, relative risk 1.31 (95% CI 0.53-3.2). Groups had similar incidence of adverse events and overall mortality (41% vs. 46%, p=0.75).

CONCLUSIONS

In patients with ALF at high risk of ICH, MH at 33-34°C did not confer a benefit above management at 36°C in prevention of ICH or in overall survival. This study did not confirm advantage of its prophylactic use. (ISRCTN registration number 74268282; no funding.)

LAY SUMMARY

Studies in animals with acute liver failure (ALF) have suggested that cooling (hypothermia) could prevent or limit the development of brain swelling, a dangerous complication of the condition. There is limited data on its effects in humans. In a randomized controlled trial in severely ill patients with ALF we compared the effects of different temperatures and found no benefit on improving survival or preventing brain swelling by controlling temperature at 33-34°C against 36°C.

Role of inflammation and infection in the pathogenesis of human acute liver failure: Clinical implications for monitoring and therapy

Acute liver failure is a rare and devastating clinical condition. At present, emergency liver transplantation is the only life-saving therapy in advanced cases, yet the feasibility of transplantation is affected by the presence of systemic inflammation, infection and resultant multi-organ failure. The importance of immune dysregulation and acquisition of infection in the pathogenesis of acute liver failure and its associated complications is now recognised. In this review we discuss current thinking regarding the role of infection and inflammation in the pathogenesis of and outcome in human acute liver failure, the implications for the management of such patients and suggest directions for future research.

Mild hypothermia attenuate kidney injury in canines with oleic acid-induced acute respiratory distress syndrome

BACKGROUND

Hypothermia may attenuate ventilator induced-lung injury in acute respiratory distress syndrome (ARDS). However, the impact of hypothermia on extra-pulmonary organ injury in ARDS remains unclear. The purpose of this study was to investigate whether hypothermia affects extra-pulmonary organ injury in a canine ARDS model induced by oleic acid.

OBJECTIVES

Twelve anesthetized canines with oleic acid-induced ARDS were randomly divided (n=6 per group) into a hypothermia group (core temperature of 33±1°C, HT group) and a normothermia group (core temperature of 38±1°C, NT group) and treated for four hours. The liver, small intestine and kidney were assessed by evaluating biochemical parameters, plasma and tissue cytokine levels, and tissue histopathological injury scores.

RESULTS

The HT group showed a lower plateau pressure, lung elastance and pulmonary vascular resistance. Hypothermia was associated with lower oxygen consumption (138.4±55.0mlmin(-1)vs. 72.0±11.2mlmin(-1), P<0.05) and higher oxygen saturation of mixed venous blood (62.8%±8.0% vs. 77.5%±10.1%, P<0.05). Both groups had similar levels of tumour necrosis factor-α in the plasma and extra-pulmonary organ, however, plasma interleukin-10 (97.1±25.0pgml(-1)vs. 131.4±27.0pgml(-1), P<0.05) was higher in the HT group. Further, the animals in the HT group had a lower levels of plasma creatinine (54.6±19.1UL(-1)vs. 29.1±8.0UL(-1), P<0.05), and lower renal histopathological injury scores [4.0(3.5;7.0) vs. 1.5(0.8;3.0), P<0.05]. Hypothermia did not affect the histopathological injury of the liver and small intestine.

CONCLUSIONS

Short-term mild hypothermia can reduce lung elastance and pulmonary vascular resistance, increase the systemic anti-inflammatory response and attenuate kidney histopathological injury in a canine ARDS model induced by oleic acid.

Inferior Vena Cava Thrombosis Related to Hypothermia Catheter: Report of 20 Consecutive Cases

BACKGROUND

Temperature management using endovascular catheters is an established therapy in neurointensive care. Nonetheless, several case series have reported a high rate of thrombosis related to the use of endovascular hypothermia catheters.

METHODS

As a result of a pulmonary embolism that developed in a patient after removing an inferior vena cava hypothermia catheter, we designed a clinical protocol for managing and removing these devices. First, an invasive cavography was performed before the removal of the catheter. If there was a thrombus, a cava vein filter was inserted through jugular access. After that, the catheter was removed.

RESULTS

The venography found inferior vena cava thrombi in 18 of 20 consecutive patients. A concomitant ultrasonography study showed vena cava thrombosis in only three patients. A vena cava filter was inserted in all patients where thrombi were found, without any significant complication. Anticoagulation was started in all patients. No symptomatic pulmonary embolism was diagnosed until the time of discharge.

CONCLUSIONS

The frequency of thrombosis related to temperature management catheters is extremely high (90 %). Furthermore, ultrasonography has a very low sensibility to detect cava vein thrombosis (16.7 %). The real meaning of our findings is unknown, but other temperature control systems could be a safer option. More studies are needed to confirm our findings.

Therapeutic Hypothermia in Spinal Cord Injury: The Status of Its Use and Open Questions

Spinal cord injury (SCI) is a major health problem and is associated with a diversity of neurological symptoms. Pathophysiologically, dysfunction after SCI results from the culmination of tissue damage produced both by the primary insult and a range of secondary injury mechanisms. The application of hypothermia has been demonstrated to be neuroprotective after SCI in both experimental and human studies. The myriad of protective mechanisms of hypothermia include the slowing down of metabolism, decreasing free radical generation, inhibiting excitotoxicity and apoptosis, ameliorating inflammation, preserving the blood spinal cord barrier, inhibiting astrogliosis, promoting angiogenesis, as well as decreasing axonal damage and encouraging neurogenesis. Hypothermia has also been combined with other interventions, such as antioxidants, anesthetics, alkalinization and cell transplantation for additional benefit. Although a large body of work has reported on the effectiveness of hypothermia as a neuroprotective approach after SCI and its application has been translated to the clinic, a number of questions still remain regarding its use, including the identification of hypothermia's therapeutic window, optimal duration and the most appropriate rewarming rate. In addition, it is necessary to investigate the neuroprotective effect of combining therapeutic hypothermia with other treatment strategies for putative synergies, particularly those involving neurorepair.

Circulating microRNAs Reveal Time Course of Organ Injury in a Porcine Model of Acetaminophen-Induced Acute Liver Failure

Acute liver failure is a rare but catastrophic condition which can progress rapidly to multi-organ failure. Studies investigating the onset of individual organ injury such as the liver, kidneys and brain during the evolution of acute liver failure, are lacking. MicroRNAs are short, non-coding strands of RNA that are released into the circulation following tissue injury. In this study, we have characterised the release of both global microRNA and specific microRNA species into the plasma using a porcine model of acetaminophen-induced acute liver failure. Pigs were induced to acute liver failure with oral acetaminophen over 19h±2h and death occurred 13h±3h thereafter. Global microRNA concentrations increased 4h prior to acute liver failure in plasma (P<0.0001) but not in isolated exosomes, and were associated with increasing plasma levels of the damage-associated molecular pattern molecule, genomic DNA (P<0.0001). MiR122 increased around the time of onset of acute liver failure (P<0.0001) and was associated with increasing international normalised ratio (P<0.0001). MiR192 increased 8h after acute liver failure (P<0.0001) and was associated with increasing creatinine (P<0.0001). The increase in miR124-1 occurred concurrent with the pre-terminal increase in intracranial pressure (P<0.0001) and was associated with decreasing cerebral perfusion pressure (P<0.002). Conclusions: MicroRNAs were released passively into the circulation in response to acetaminophen-induced cellular damage. A significant increase in global microRNA was detectable prior to significant increases in miR122, miR192 and miR124-1, which were associated with clinical evidence of liver, kidney and brain injury respectively.

Acute liver failure in dogs and cats

OBJECTIVE

To define acute liver failure (ALF), review the human and veterinary literature, and discuss the etiologies and current concepts in diagnostic and treatment options for ALF in veterinary and human medicine.

ETIOLOGY

In veterinary medicine ALF is most commonly caused by hepatotoxin exposure, infectious agents, inflammatory diseases, trauma, and hypoxic injury.

DIAGNOSIS

A patient may be deemed to be in ALF when there is a progression of acute liver injury with no known previous hepatic disease, the development of hepatic encephalopathy of any grade that occurs within 8 weeks after the onset of hyperbilirubinemia (defined as plasma bilirubin >50 μM/L [>2.9 mg/dL]), and the presence of a coagulopathy. Diagnostic testing to more specifically characterize liver dysfunction or pathology is usually required.

THERAPY

Supportive care to aid the failing liver and compensate for the lost functions of the liver remains the cornerstone of care of patients with ALF. Advanced therapeutic options such as extracorporeal liver assist devices and transplantation are currently available in human medicine.

PROGNOSIS

The prognosis for ALF depends upon the etiology, the degree of liver damage, and the response to therapy. In veterinary medicine, the prognosis is generally poor.

Management in acute liver failure

Acute liver failure (ALF) is a rare, potentially fatal complication of severe hepatic illness resulting from various causes. In a clinical setting, severe hepatic injury is usually recognised by the appearance of jaundice, encephalopathy and coagulopathy. The central and most important clinical event in ALF is occurrence of hepatic encephalopathy (HE) and cerebral edema which is responsible for most of the fatalities in this serious clinical syndrome. The pathogenesis of encephalopathy and cerebral edema in ALF is unique and multifactorial. Ammonia plays a central role in the pathogenesis. The role of newer ammonia lowering agents is still evolving. Liver transplant is the only effective therapy that has been identified to be of promise in those with poor prognostic factors, whereas in the others, aggressive intensive medical management has been documented to salvage a substantial proportion of patients. A small fraction of patients undergo liver transplant and the remaining are usually treated with medical therapy. Therefore, identification of the complications and causes of death in such patients, and use of appropriate prognostic models to identify those who need liver transplant and those who can be managed with medical treatment is a vital component of therapeutic strategy. In this review, we discuss the various pathogenetic mechanisms and treatment options available.

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).

Fatal hyperammonemia after repeat renal transplantation

A 35-year-old man had symptomatic hyperammonemia and normal liver function after repeat kidney transplantation. He presented with gastrointestinal symptoms, which quickly progressed to altered mental status. Therapy was instituted to clear the ammonia, but the ammonia level continued to rise. Eventually, the patient became unresponsive, and an emergent computed tomographic scan showed cerebral herniation. Urine acids and serum organic acids were not diagnostic of any urea cycle disorder. Histology did not reveal a clear etiology for the hyperammonemia.

Thermoregulation and Risk of Surgical Site Infection

Surgical site infections (SSIs) occur in approximately 2%–5% of patients undergoing surgery in the acute care setting in the United States. These infections result in increased length of stay, higher risk of death, and increased cost of care compared with that in uninfected surgical patients. Given the inclusion of maintenance of perioperative normothermia for all major surgeries as a means of lowering the risk of infection in the Surgical Care Improvement Project 2009, we prepared a summary of the literature to determine the strength and quantity of the evidence underlying the performance measure. Although the data are generally supportive of perioperative normothermia as a means of reducing the risk of SSIs, a more rigorous approach using standard SSI definitions as well as standardized temperature measurements (and timing thereof) will further delineate the role played by temperature regulation in SSI development.

Intensive care unit management of patients with liver failure

Acute liver failure (ALF) and acute-on-chronic liver failure (ACLF) usually mandate management within an intensive care unit (ICU). Even though the conditions bear some similarities, precipitating causes, and systemic complications management practices differ. Although early identification of ALF and ACLF, improvements in ICU management, and the widespread availability of liver transplantation have improved mortality, optimal management practices have not been defined. This article summarizes current ICU management practices and identifies areas of management that require further study.

Clinical hypothermia temperatures increase complement activation and cell destruction via the classical pathway

Background

Therapeutic hypothermia is a treatment modality that is increasingly used to improve clinical neurological outcomes for ischemia-reperfusion injury-mediated diseases. Antibody-initiated classical complement pathway activation has been shown to contribute to ischemia-reperfusion injury in multiple disease processes. However, how therapeutic hypothermia affects complement activation is unknown. Our goal was to measure the independent effect of temperature on complement activation, and more specifically, examine the relationship between clinical hypothermia temperatures (31–33°C), and complement activation.

Methods

Antibody-sensitized erythrocytes were used to assay complement activation at temperatures ranging from 0-41°C. Individual complement pathway components were assayed by ELISA, Western blot, and quantitative dot blot. Peptide Inhibitor of complement C1 (PIC1) was used to specifically inhibit activation of C1.

Results

Antibody-initiated complement activation resulting in eukaryotic cell lysis was increased by 2-fold at 31°C compared with 37°C. Antibody-initiated complement activation in human serum increased as temperature decreased from 37°C until dramatically decreasing at 13°C. Quantitation of individual complement components showed significantly increased activation of C4, C3, and C5 at clinical hypothermia temperatures. In contrast, C1s activation by heat-aggregated IgG decreased at therapeutic hypothermia temperatures consistent with decreased enzymatic activity at lower temperatures. However, C1q binding to antibody-coated erythrocytes increased at lower temperatures, suggesting that increased classical complement pathway activation is mediated by increased C1 binding at therapeutic hypothermia temperatures. PIC1 inhibited hypothermia-enhanced complement-mediated cell lysis at 31°C by up to 60% (P = 0.001) in a dose dependent manner.

Conclusions

In summary, therapeutic hypothermia temperatures increased antibody-initiated complement activation and eukaryotic cell destruction suggesting that the benefits of therapeutic hypothermia may be mediated via other mechanisms. Antibody-initiated complement activation has been shown to contribute to ischemia-reperfusion injury in several animal models, suggesting that for diseases with this mechanism hypothermia-enhanced complement activation may partially attenuate the benefits of therapeutic hypothermia.

Management of hepatic encephalopathy

OPINION STATEMENT

Hepatic encephalopathy management varies depending on the acuity of liver failure. However, in patients with either acute or chronic liver failure five basic steps in management are critical: stabilization, addressing modifiable precipitating factors, lowering blood ammonia, managing elevated intracranial pressure (ICP) (if present), and managing complications of liver failure that can contribute to encephalopathy, particularly hyponatremia. Because liver failure patients are prone to a variety of other medical problems that can lead to encephalopathy (such as coagulopathy associated intracranial hemorrhage, electrolyte disarray, renal failure, hypotension, hypoglycemia, and infection), a thorough history, physical and neurologic examination is mandated in all encephalopathic liver failure patients. There should be a low threshold for brain imaging in patients with focal neurological deficits given the propensity for spontaneous intracranial hemorrhage. In patients with acute liver failure and high grade encephalopathy, identification of the etiology of acute liver failure is essential to guide treatment and antidote administration, particularly in the case of acetaminophen poisoning. Equally critical is management of elevated ICP in acute liver failure. Intracranial hypertension can be treated with hypertonic saline and/or adjustment of the dialysis bath. Placement of an intracranial monitor to guide ICP therapy is risky because of concomitant coagulopathy and remains controversial. Continuous renal replacement therapy may help lower serum ammonia, treat coexisting uremia, and improve symptoms. Liver transplantation is the definitive treatment for patients with acute liver failure and hepatic encephalopathy. In patients with chronic hepatic encephalopathy, lactulose and rifaxamin remain a mainstay of therapy. In these patients, it is essential to identify reversible causes of hepatic encephalopathy such as increased ammonia production and/or decreased clearance (eg, infection, GI bleed, constipation, hypokalemia, dehydration). Chronic hyponatremia should be managed by gradual sodium correction of no more than 8‒12 meq/L per day to avoid central myelinolysis syndrome. Free water restriction and increased dietary sodium are reasonable, cost effective treatment options. Many emerging therapies, both pharmacologic and interventional, are currently being studied to improve management of hepatic encephalopathy.

Monitoring and managing hepatic disease in anaesthesia

Patients with liver disease have multisystem organ dysfunction that leads to physiological perturbations ranging from hyperbilirubinaemia of no clinical consequence to severe coagulopathy and metabolic disarray. Patient-specific risk factors, clinical scoring systems, and surgical procedures stratify perioperative risk for these patients. The anaesthetic management of patients with hepatic dysfunction involves consideration of impaired drug metabolism, hyperdynamic circulation, perioperative hypoxaemia, bleeding, thrombosis, and hepatic encephalopathy.