Liver transplantation in patients with liver failure related to exertional heatstroke

Vancomycin modestly attenuates symptom severity during onset of and recovery from exertional heat stroke in mice

Increased intestinal permeability during exertion and subsequent leakage of bacteria into circulation is hypothesized to accelerate exertional heat stroke (EHS) onset and/or exacerbate EHS severity. To provide proof of concept for this theory, we targeted intestinal microbiota via antibiotic prophylaxis and determined whether vancomycin would delay EHS onset and/or mitigate EHS severity and mortality rates using a mouse model of EHS. Mice were 1) designated as EHS or Exercise Control (ExC) and 2) given 7 days of vancomycin (VEHS, VExC) or untreated water (EHS, ExC) before EHS/Exercise. Following EHS/ExC, mice were euthanized immediately (0 h) or returned to their home cage (25°C) and euthanized after 3 h or 24 h. VEHS mice exhibited reduced abundance and altered composition of fecal bacteria (with notable decreases in genera within orders Clostridiales and Bacteroidales); increased water consumption, lower core temperature (TC) before and during heating (TCMax), lower circulating markers of organ damage and inflammation at 24 h; and reduced hepatic activation of stress pathways at 0 and 3 h compared with EHS mice. Vancomycin-induced alterations to the intestinal microbiota likely influenced EHS outcomes, but it is unconfirmed whether this is due to attenuated bacterial leakage into circulation or other (in)direct effects on physiology and behavior (e.g., decreased TC, increased water consumption). To our knowledge, this is the first study quantitating antibiotic effects in conscious/unanesthetized, exertional HS animals.NEW & NOTEWORTHY Vancomycin prophylaxis lowered core temperature before and during EHS, mitigated EHS-associated rise of hepatic biomarkers and cytokines/chemokines in circulation (particularly at 24 h), and corresponded to inhibited phosphorylation of hepatic c-Jun NH2-terminal kinase on Threonine 183/Tyrosine 185 at 0 and 3 h in conscious, unanesthetized mice. However, vancomycin also induced cecal enlargement suggesting its off-target effects could limit its utility against EHS.

Fatal heat stroke based on foudroyant irreversible multiple organ dysfunction in German summer

Objectives

Heat stroke is a serious condition that might lead from moderate organ impairment to multiple organ dysfunction syndrome. Appropriate diagnosis-finding, fast initiation of cooling and intensive care are key measures of the initial treatment. Scientific case report based on i) clinical experiences obtained in the clinical management of a particularly rare case and ii) selected references from the medical scientific literature.

Case presentation

We present a case of a young and healthy construction worker who suffered from an exertional heat stroke with a body core temperature exceeding 42 °C by previous several hour work at 35 °C ambient temperature. Heat stroke was associated with foudroyant, not reversible multiple organ dysfunction syndrome, in particular, early disturbed coagulation, microcirculatory, liver and respiratory failure, and subsequent fatal outcome despite immediate diagnosis-finding, rapid external cooling and expanded intensive care management.

Conclusions

Basic knowledge on an adequate diagnosis(-finding in time) and treatment of heat stroke is important for (almost each) physician in the summertime as well as is essential for the initiation of an appropriate management. Associated high morbidity and mortality rates indicate the need for implementation of standard operation protocols.

Critical illness aspects of heatstroke: A hot topic

Heatstroke represents the most severe end of the heat illness spectrum, and is increasingly seen in those undergoing exercise or exertion ('exertional heatstroke') and those exposed to high ambient temperatures, for example in heatwaves ('classical heatstroke'). Both forms may be associated with significant thermal injury, leading to organ dysfunction and the need for admission to an intensive care unit. The process may be exacerbated by translocation of bacteria or endotoxin through an intestinal wall rendered more permeable by the hyperthermia. This narrative review highlights the importance of early diagnosis, rapid cooling and effective management of complications. It discusses the incidence, clinical features and treatment of heatstroke, and discusses the possible role of intestinal permeability and advances in follow-up and recovery of this condition. Optimum treatment involves an integrated input from prehospital, emergency department and critical care teams, along with follow-up by rehabilitation teams and, if appropriate, sports or clinical physiologists.

Heat Stroke Leading to a Fatal Outcome

Heat stroke (HS) can cause several physiological changes in the body. In its most severe form, it can cause multi-organ failure including encephalopathy, circulatory shock, liver failure, renal failure, disseminated intravascular coagulation, and rhabdomyolysis among others. HS is a preventable condition; however, it can be life-threatening in severe forms. We present a case of HS in a 54-year-old male, with rapidly progressive multi-organ failure and a fatal outcome along with a brief literature review.

The pathogenesis and therapeutic strategies of heat stroke-induced liver injury

Heat stroke (HS) is a life-threatening systemic disease characterized by an elevated core body temperature of more than 40 ℃ and subsequent multiple organ dysfunction syndrome. With the growing frequency of global heatwaves, the incidence rate of HS has increased significantly, which has caused a huge burden on people's lives and health. Liver injury is a well-documented complication of HS and usually constitutes the direct cause of patient death. In recent years, a lot of research has been carried out on the pathogenesis and treatment strategies of HS-induced liver injury. In this review, we summarized the important pathogenesis of HS-induced liver injury that has been confirmed so far. In addition to the comprehensive effect of systemic factors such as heat cytotoxicity, coagulopathy, and systemic inflammatory response syndrome, excessive hepatocyte cell pyroptosis, dysfunction of Kupffer cells, abnormal expression of heat shock protein expression, and other factors are also involved in the pathogenesis of HS-induced liver injury. Furthermore, we have also established the current therapeutic strategies for HS-induced liver injury. Our study is of great significance in promoting the understanding of the pathogenesis and treatment of HS-induced liver injury.

Identification of therapeutic targets in a murine model of severe exertional heat stroke

Exertional heat stroke (EHS) is a potentially lethal condition resulting from high core body temperatures (TC) in combination with a systemic inflammatory response syndrome (SIRS) with varying degrees of severity across victims, and limited understanding of the underlying mechanism(s). We established a mouse model of severe EHS to identify mechanisms of hyperthermia/inflammation that may be responsible for organ damage. Mice were forced to run on a motorized wheel in a 37.5°C chamber until loss of consciousness and were either removed immediately (exertional heat injury or EHI; TCMax = 42.4 ± 0.2°C) or remained in the chamber an additional 20 min (EHS; TCMax = 42.5 ± 0.4°C). Exercise control mice (ExC) experienced identical procedures to EHS at 25°C. At 3 h post-EHS, there was evidence for an immune/inflammatory response as elevated blood chemokine [interferon γ-induced protein 10 (IP-10), keratinocytes-derived chemokine (KC), macrophage inflammatory proteins (MIP-1α), MIP-1β, MIP-2] and cytokine [granulocyte colony-stimulating factor (G-CSF), interleukins (IL-10), IL-6] levels peaked and were highest in EHS mice compared with EHI and ExC mice. Immunoblotting of organs susceptible to EHS damage indicated that several kinases were sensitive to stress associated with heat/inflammation and exercise; specifically, phosphorylation of liver c-Jun NH2-terminal kinase (JNK) at threonine 183/tyrosine 185 immediately (0 h) postheating related to heat illness severity. We have established a mouse EHS model, and JNK [or its downstream target(s)] could underlie EHS symptomatology, allowing the identification of molecular pathways or countermeasure targets to mitigate heat illness severity, enable complete recovery, and decrease overall EHS-related fatalities.

Exertional Heat Stroke-Induced Acute Liver Failure and Liver Transplantation

Exertional heat stroke is a medical emergency characterized by excessive heat production and inadequate heat dissipation usually after heavy exertion in hot and humid climates and can be associated with multiorgan failure. Treatment is largely supportive, but liver transplantation (LT) may be necessary in select patients. Here, we report the case of a 44-year-old runner who was found unconscious after a 5-mile run and developed acute liver failure. He underwent successful LT 1 week later when he developed encephalopathy. This case report illustrates the importance of early LT referral in patients with exertional heat stroke-induced acute liver failure.

Machine learning-based mortality prediction model for heat-related illness

In this study, we aimed to develop and validate a machine learning-based mortality prediction model for hospitalized heat-related illness patients. After 2393 hospitalized patients were extracted from a multicentered heat-related illness registry in Japan, subjects were divided into the training set for development (n = 1516, data from 2014, 2017–2019) and the test set (n = 877, data from 2020) for validation. Twenty-four variables including characteristics of patients, vital signs, and laboratory test data at hospital arrival were trained as predictor features for machine learning. The outcome was death during hospital stay. In validation, the developed machine learning models (logistic regression, support vector machine, random forest, XGBoost) demonstrated favorable performance for outcome prediction with significantly increased values of the area under the precision-recall curve (AUPR) of 0.415 [95% confidence interval (CI) 0.336–0.494], 0.395 [CI 0.318–0.472], 0.426 [CI 0.346–0.506], and 0.528 [CI 0.442–0.614], respectively, compared to that of the conventional acute physiology and chronic health evaluation (APACHE)-II score of 0.287 [CI 0.222–0.351] as a reference standard. The area under the receiver operating characteristic curve (AUROC) values were also high over 0.92 in all models, although there were no statistical differences compared to APACHE-II. This is the first demonstration of the potential of machine learning-based mortality prediction models for heat-related illnesses.

Bone marrow mesenchymal stem cells combine with normothermic machine perfusion to improve rat donor liver quality-the important role of hepatic microcirculation in donation after circulatory death

Donation after circulatory death (DCD) can expand the donor pool effectively. A gap remains in outcome between DCD livers and living donor livers, warranting improved DCD liver quality and urgent resolution. Bone marrow mesenchymal stem cells (BMMSCs) can regulate immunity, participate in the anti-inflammatory response, and secrete cytokines. We investigated the effect of BMMSCs combined with normothermic machine perfusion (NMP) on DCD liver quality, and the role of microcirculation therein. Rat thoracic aortas were clipped to obtain DCD livers, and a rat NMP system was established. The DCD livers were grouped by preservation method: normal, static cold storage (SCS), NMP (P), and BMMSCs plus NMP (BP); storage time was up to 8 h. Liver function in outflow perfusate was detected by biochemical methods; liver tissue histopathology was observed by hematoxylin–eosin staining; hepatocyte ultrastructure was observed by transmission electron microscopy; hepatocyte apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling; liver microcirculation–related indicators were detected by immunofluorescence, immunohistochemistry, Western blotting, and enzyme-linked immunosorbent assay. Compared with SCS, P and BP significantly improved liver function and liver histological damage, reduced hepatocyte apoptosis, and repaired hepatocyte mitochondrial damage after 6 h in vitro. BP also significantly inhibited intrahepatic macrophage activation and intercellular adhesion, improved endothelial damage, and significantly improved endothelin 1–nitric oxide balance and microcirculation perfusion. In conclusion, BP can improve DCD liver microcirculation and quality. The mechanism may be the improvement of improve hepatic sinusoidal endothelial injury and microcirculation perfusion by inhibiting macrophage activation and intercellular adhesion.

The Fire from Within: Multiorgan Failure with Bimodal Rhabdomyolysis from Exertional Heat Stroke

Heat stroke (HS) is a condition characterized by a rise in core body temperature and central nervous system dysfunction. It is divided into two types: classical and exertional. Exertional heat stroke (EHS) is accompanied by organ failure. Liver injury, presenting only with a rise in liver enzymes, is common but in rare conditions, acute liver failure (ALF) may ensue, leading to a potentially lethal condition. Most cases of EHS-induced ALF are managed conservatively. However, liver transplantation is considered for cases refractory to supportive treatment. Identifying patients eligible for liver transplantation in the context of an EHS-induced ALF becomes a medical dilemma since the conventional prognostic criterion may be difficult to apply, and there is paucity of literature about these specific sets of individuals. Recently, extracorporeal liver support has been gaining popularity for patients with liver failure as a bridge to liver transplant. In this case report, we present a young Filipino athlete with symptoms and clinical course consistent with EHS that developed multiorgan failure, initially considered a candidate for liver transplant and total plasma exchange, but clinically improved with supportive management alone. This patient was also found to have bimodal rhabdomyolysis during the course of his hospital stay as manifested by the bimodal rise in his creatine kinase enzymes.

Severe Acute Liver Injury Related to Heat Stroke

Heat stroke (HS) is a life-threatening condition characterized by hyperthermia and multiple organ failure. Mild to moderate hepatocellular injury is a well-documented complication but severe liver injury and acute liver failure are rare. There are neither established criteria nor optimal timing for liver transplantation and conservative management seems to be the cornerstone treatment. The authors report a case of a patient with severe liver injury related to HS who recovered completely under conservative treatment.

Controversies in exertional heat stroke diagnosis, prevention, and treatment

During the past several decades, the incidence of exertional heat stroke (EHS) has increased dramatically. Despite an improved understanding of this syndrome, numerous controversies still exist within the scientific and health professions regarding diagnosis, pathophysiology, risk factors, treatment, and return to physical activity. This review examines the following eight controversies: 1) reliance on core temperature for diagnosing and assessing severity of EHS; 2) hypothalamic damage induces heat stroke and this mediates “thermoregulatory failure” during the immediate recovery period; 3) EHS is a predictable condition primarily resulting from overwhelming heat stress; 4) heat-induced endotoxemia mediates systemic inflammatory response syndrome in all EHS cases; 5) nonsteroidal anti-inflammatory drugs for EHS prevention; 6) EHS shares similar mechanisms with malignant hyperthermia; 7) cooling to a specific body core temperature during treatment for EHS; and 8) return to physical activity based on physiological responses to a single-exercise heat tolerance test. In this review, we present and discuss the origins and the evidence for each controversy and propose next steps to resolve the misconception.

L’hépatite hypoxique : ce que le réanimateur doit savoir

L’hépatite hypoxique est secondaire à une inadéquation entre les besoins hépatiques en oxygène et les apports sanguins. Elle est caractérisée par une augmentation rapide et transitoire de l’activité des transaminases sériques, prédominant souvent sur l’aspartate aminotransférase, chez un patient avec une ou plusieurs comorbidité(s), en particulier cardiaque(s). Le diagnostic est clinicobiologique et ne nécessite pas, en général, d’examen d’imagerie ou d’anatomopathologie. La lésion histologique sous-jacente est une nécrose de la zone centrale du lobule hépatique. L’hépatite hypoxique est souvent associée à une insuffisance rénale aiguë. Les facteurs de risque sont les cardiopathies favorisant la congestion hépatique, les hypoxémies, les altérations de lamicrocirculation hépatique, telles qu’on les observe au cours de la cirrhose. La prise en charge repose sur la correction de l’événement aigu et la restauration d’une perfusion et d’une oxygénation hépatique appropriées. Le pronostic est sombre avec une mortalité proche de 50 % et dépend essentiellement du délai de prise en charge de l’événement causal. Il est classique d’observer un syndrome de cholestase après une hépatite hypoxique résolutive. La lésion sous-jacente, encore mal comprise, est probablement une ischémie des petites voies biliaires intrahépatiques qui peut conduire, parfois, à des cholangites sclérosantes secondaires. L’objectif de cet article est de fournir au réanimateur l’ensemble des outils lui permettant d’identifier les situations à risque d’hépatite hypoxique et d’en faire le diagnostic le plus précocement possible afin de mettre en œuvre les mesures nécessaires.

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.