Acute Liver Failure From Exertional Heatstroke Can Result in Excellent Long-Term Survival With Liver Transplantation

Physiological responses to heat exposure in a general population cohort in Denmark: the Lolland-Falster Health Study

BACKGROUND

Rising global temperatures due to climate change pose a health risk. Mortality and morbidity increase during heat events affects various organ systems. While warmer countries face higher risks, even colder regions show elevated mortality during hot periods. This study examines physiological responses to heat exposure using data from the general Danish population cohort Lolland-Falster Health Study (LOFUS) during the summers of 2016-2019.

METHODS

In this cross-sectional study, we analysed health data from 3804 individuals aged ≥15 years. Data were analysed across organ systems: cardiovascular system, lung function, renal system, inflammation, coagulation, and liver function. Meteorological data from the Danish Meteorological Institute provided information on temperature and humidity. Heat exposure was defined as one day ≥28°C heat index the day prior to examination. Adjusted multiple linear regression was applied to analyse differences between the two groups.

RESULTS

There were 46 of 368 days with temperatures ≥28°C heat index. In total, 396 participants were heat-exposed (exposure group), while 3408 constituted the unexposed group. Heat exposure was associated with lower systolic blood pressure (-3.82 mm Hg [-5.72; -1.93]), higher heart rate (1.71 beats/min [0.45; 2.98]), lower oxygen saturation (-0.28% [-0.45; -0.10]), higher sodium (0.56 mmol/l [0.33; 0.79]), and higher urine albumin (0.14 mg/l [0.02; 0.27]). No significant differences were observed in inflammation, coagulation, or liver function.

CONCLUSION

This study reveals early physiological responses to heat with one day of heat exposure ≥28°C, particularly in the cardiovascular, pulmonary, and renal systems. These findings underline the need for tailored strategies to mitigate health risks associated with rising temperatures.

Risk Factor Analysis and Nomogram for Predicting In-Hospital Mortality in ICU Patients with Heat Stroke: A National Multicenter Study

Objective

The aim of this nationwide multicenter study was to ascertain the risk factors associated with in-hospital mortality in patients with heat stroke admitted to intensive care units (ICUs) and to develop a nomogram for prognostic prediction.

Methods

A retrospective analysis was conducted on clinical data collected from ICU patients diagnosed with heat stroke across multiple centers nationwide. Univariate and multivariate logistic regression analyses were performed to identify significant risk factors for in-hospital mortality. Based on the results of the multivariate analysis, a nomogram was constructed to estimate the individualized probability of mortality. Internal validation of the nomogram was performed, and its performance was assessed using receiver operating characteristic (ROC) curves, calibration plots, and decision curve analysis (DCA).

Results

A total of 292 ICU patients with heat stroke were included in this study. Three risk factors, namely Cr (creatinine), AST (aspartate aminotransferase), and SBP (systolic blood pressure), were found to be significantly associated with in-hospital mortality. These risk factors were incorporated into the nomogram, which exhibited good discriminative ability (area under the ROC curve of the training and validation cohorts were 0.763 and 0.739, respectively) and calibration. Internal validation and decision curve analysis confirmed the stability and reliability of the nomogram.

Conclusion

This nationwide multicenter study identified key risk factors for in-hospital mortality in ICU patients with heat stroke. The developed nomogram provides an individualized prediction of mortality risk and can serve as a valuable tool for clinicians in the assessment and management of ICU patients with heat stroke.

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.

ZBP1 and heatstroke

Heatstroke, which is associated with circulatory failure and multiple organ dysfunction, is a heat stress-induced life-threatening condition characterized by a raised core body temperature and central nervous system dysfunction. As global warming continues to worsen, heatstroke is expected to become the leading cause of death globally. Despite the severity of this condition, the detailed mechanisms that underlie the pathogenesis of heatstroke still remain largely unknown. Z-DNA-binding protein 1 (ZBP1), also referred to as DNA-dependent activator of IFN-regulatory factors (DAI) and DLM-1, was initially identified as a tumor-associated and interferon (IFN)-inducible protein, but has recently been reported to be a Z-nucleic acid sensor that regulates cell death and inflammation; however, its biological function is not yet fully understood. In the present study, a brief review of the main regulators is presented, in which the Z-nucleic acid sensor ZBP1 was identified to be a significant factor in regulating the pathological characteristics of heatstroke through ZBP1-dependent signaling. Thus, the lethal mechanism of heatstroke is revealed, in addition to a second function of ZBP1 other than as a nucleic acid sensor.

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.

Cytosolic p53 Inhibits Parkin-Mediated Mitophagy and Promotes Acute Liver Injury Induced by Heat Stroke

Heat stroke (HS) is a severe condition characterized by increased morbidity and high mortality. Acute liver injury (ALI) is a well-documented complication of HS. The tumor suppressor p53 plays an important role in regulation of mitochondrial integrity and mitophagy in several forms of ALI. However, the role of p53-regulated mitophagy in HS-ALI remains unclear. In our study, we discovered the dynamic changes of mitophagy in hepatocytes and demonstrated the protective effects of mitophagy activation on HS-ALI. Pretreatment with 3-MA or Mdivi-1 significantly exacerbated ALI by inhibiting mitophagy in HS-ALI mice. Consistent with the animal HS-ALI model results, silencing Parkin aggravated mitochondrial damage and apoptosis by inhibiting mitophagy in HS-treated normal human liver cell line (LO2 cells). Moreover, we described an increase in the translocation of p53 from the nucleus to the cytoplasm, and cytosolic p53 binds to Parkin in LO2 cells following HS. p53 overexpression using a specific adenovirus or Tenovin-6 exacerbated HS-ALI through Parkin-dependent mitophagy both in vivo and in vitro, whereas inhibition of p53 using siRNA or PFT-α effectively reversed this process. Our results demonstrate that cytosolic p53 binds to Parkin and inhibits mitophagy by preventing Parkin's translocation from the cytosol to the mitochondria, which decreases mitophagy activation and leads to hepatocyte apoptosis in HS-ALI. Overall, pharmacologic induction of mitophagy by inhibiting p53 may be a promising therapeutic approach for HS-ALI treatment.

Classic and exertional heatstroke

In the past two decades, record-breaking heatwaves have caused an increasing number of heat-related deaths, including heatstroke, globally. Heatstroke is a heat illness characterized by the rapid rise of core body temperature above 40 °C and central nervous system dysfunction. It is categorized as classic when it results from passive exposure to extreme environmental heat and as exertional when it develops during strenuous exercise. Classic heatstroke occurs in epidemic form and contributes to 9-37% of heat-related fatalities during heatwaves. Exertional heatstroke sporadically affects predominantly young and healthy individuals. Under intensive care, mortality reaches 26.5% and 63.2% in exertional and classic heatstroke, respectively. Pathological studies disclose endothelial cell injury, inflammation, widespread thrombosis and bleeding in most organs. Survivors of heatstroke may experience long-term neurological and cardiovascular complications with a persistent risk of death. No specific therapy other than rapid cooling is available. Physiological and morphological factors contribute to the susceptibility to heatstroke. Future research should identify genetic factors that further describe individual heat illness risk and form the basis of precision-based public health response. Prioritizing research towards fundamental mechanism and diagnostic biomarker discovery is crucial for the design of specific management approaches.

[Lethal Heatstroke with Disseminated Intravascular Coagulopathy]

We report on a case of severe heat stroke due to extended exposure to the sun in an enclosed glass cabin of an agricultural vehicle. Patient treatment, lab results and complications are reported and we examine the current literature on heat stroke.Heat stroke is a very rare and highly severe condition mostly suffered by vulnerable individuals or individuals exposed to extreme physical strain. Per definition a heat stroke is characterized by neurological deficit (especially loss of consciousness), and a high body temperature. Most important treatment is to lower the body temperature below 40 °C as quickly as possible. The best method is cold water immersion, but there are several other physical and invasive means that can be used. If performed within 30 minutes after the beginning of the incident this treatment decreases mortality considerably.Heat damage affects every organ and organ system. Most important are neurologic deficits, cardiovascular failure, liver failure and kidney failure. The excessive heat triggers a systemic inflammatory response syndrome (SIRS) which can lead to a disseminated intravascular coagulopathy (DIC). Haemostasis is also directly affected by the elevated temperature.Besides physical cooling, there is no known specific treatment to prevent secondary damage from heat stroke. Additionally, supportive care and ICU monitoring should be applied.

Characteristics and Outcome of Exertional Heatstroke Patients Complicated by Acute Hepatic Injury: A Cohort Study

BACKGROUND AND AIMS

Exertional heatstroke (EHS) is associated with strenuous physical activity in hot environments. The present study aimed to investigate dynamic changes of hepatic function indices in EHS patients and determine risk factors for death.

METHODS

This single-center retrospective cohort study considered all patients with EHS admitted to the intensive care unit at the General Hospital of Southern Theater Command of PLA from October 2008 to May 2019. Data on general characteristics, organ function parameters, and the 90-day outcome of enrolled patients were collected. Hepatic indices were collected dynamically, and patients with acute hepatic injury (AHI) were identified by plasma total bilirubin (TBIL) ≥34.2 µmol/L and an international normalized ratio ≥1.5, or with any grade of hepatic encephalopathy.

RESULTS

In patients who survived, TBIL, alanine aminotransferase and aspartate aminotransferase were increased at 24 h, peaked at 2-3 days, and began to decrease at 5 days. In non-survivors, TBIL continuously increased post-admission. The area under the receiver operating characteristic curve for the prediction of mortality based on sequential organ failure assessment (SOFA) scores was 89.8%, and the optimal cutoff value was 7.5. Myocardial injury and infection were identified as independent risk factors for death in EHS patients with AHI.

CONCLUSIONS

In EHS patients, hepatic dysfunction usually occurred within 24 h. Patients with AHI had more severe clinical conditions, and significantly increased 90-day mortality rates. SOFA scores over 7.5, complicated with myocardial injury or infection, were found to be risk factors for death in EHS patients with AHI.

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.