Heat-Related Illness in Emergency and Critical Care: Recommendations for Recognition and Management with Medico-Legal Considerations

Analysis of clinical characteristics and risk factors for patients with heat stroke in western China in 2022: a multicenter retrospective study

Objectives

To analyzed the clinical characteristics and treatment modalities of heat stroke (HS) and to identify risk factors for a poor prognosis of HS and provide reference suggestions for its treatment and prevention.

Measurements and main results

We enrolled a total of 247 patients, with hypertension, diabetes, and psychosis being the top three comorbidities associated with HS. The incidence of HS was higher among males and older individuals. Compared to the control group, the poor prognosis group experienced higher temperatures, a higher incidence of cerebral edema, and gastrointestinal bleeding (all p < 0.05). The poor prognosis group had significantly higher blood pH, HCO3-, Lac, Scr, AST, ALT, DBIL, CKMB, PT, DD, and PLT (all p < 0.05). Furthermore, logistic regression analysis revealed that Lac, Scr, and APACHE II were risk factors for poor prognosis (p < 0.05). The AUC values for the combined diagnostic model were 0.848 (95% CI: 0.781-0.914). Male morbidity, the number of patients with combined hypertension, the prognosis, and the APACHE II score and ALT level were all greater (p < 0.05) in the CHS group. The Kaplan-Meier analysis revealed that the CHS group had a significantly higher mortality rate than the EHS group.

Conclusion

A high incidence of hypertension, diabetes, psychosis, men, and older persons may be associated with HS. HS patients with high blood cell counts, impaired coagulation, liver and kidney diseases, and those with a specific type of CHS may face a poor prognosis. In patients with heart failure, APACHE II, Lac, and Scr were independent risk factors for a poor prognosis.

Heat stress induces a three-phase thermoregulatory response in different hot and humid environments in rats

As global warming intensifies, heat waves occur more frequently around the world. Heat stress from hot and humid environments poses a significant threat to human health. It can cause a significant increase in core body temperature (CBT), and even lead to life-threatening heat stroke. Extremely high CBT is considered the most important clinical symptom and prognostic indicator of heat stroke. To study it, we implanted temperature-monitoring capsules into the abdominal cavities of rats to measure their CBT values. The rats were then exposed to different hot and humid environments to monitor the resultant changes in their CBTs. The results showed that heat stress could induce a three-phase thermoregulatory response in rats under different conditions. A temperature plateau was observed as part of the three-phase thermoregulatory response, at a similar CBT across different conditions. The duration of this plateau can reflect the thermotolerance of rats in hot and humid environments. The third stage of the three-phase thermoregulatory response reflects the pathogenesis of heat stroke, which may present the key stage of heat injury. Moreover, a certain range of humidity did not affect the thermoregulatory responses of rats, but exerted a significant impact once a certain threshold was reached. In this study, the CBTs of the rats in different environments were monitored to characterize their thermoregulatory responses under heat stress. In particular, the discovery of the plateau phase and humidity threshold may help to better understand the effects of high temperature and humidity conditions on living organisms.

Coexisting metabolic dysfunction-associated steatotic liver disease exacerbates in-hospital outcomes in patients with heat stroke

Purpose

This study aimed to investigate the impact of coexisting metabolic dysfunction-associated steatotic liver disease (MASLD) on in-hospital mortality and organ injury markers in patients with heat stroke (HS).

Approach

HS patients were retrospectively identified between July 1, 2022 and September 30, 2023 at West China Hospital, Sichuan University. Baseline characteristics, such as demographics, initial vital signs, and organ functional indicators were collected. Outcome events included organ injury and in-hospital mortality. The Least Absolute Shrinkage and Selection Operator (Lasso) method was employed to identify the optimal predictors for in-hospital mortality in HS patients. Subsequently, multivariable logistic regression analysis was performed to assess the relationship between the presence of MASLD and in-hospital mortality as well as organ function indicators.

Findings

A total of 112 patients were included in the study, in which 27 (24.1%) had coexisting MASLD. Compared to those without MASLD, patients with MASLD had higher levels of various organ injury markers such as aspartate aminotransferase, urea nitrogen, serum cystatin C, creatinine, uric acid, myoglobin, creatine kinase and its isoenzymes upon admission (P < 0.05). The multivariable Logistic regression analysis indicated that the presence of MASLD is an independent risk factor for in-hospital mortality in HS patients.

Conclusion

This study firstly indicated that coexisting MASLD may exacerbate organ injury in HS patients and serve as an independent risk factor for in-hospital mortality.

How can heatstroke damage the brain? A mini review

Record-breaking heat waves over the past 20 years have led to a global increase in heat-related deaths, including heatstroke. Heat-related illnesses occur when the body cannot adapt to the elevated temperatures in the environment, leading to various symptoms. In severe situations, such as heatstroke, the body temperature can rise above 40°C, leading to significant injury to body systems, with particular susceptibility of the central nervous system (CNS). Neuroimaging studies conducted months or years after a heatstroke have revealed cellular damage in the cerebellum and other brain regions, including the hippocampus, midbrain, and thalamus, with the potential for long-term neurological complications in survivors of a heatstroke. This mini review aimed to describe the mechanisms and pathways underlying the development of brain injury induced by heatstroke and identify diagnostic imaging tools and biomarkers for injury to the CNS due to a heatstroke.

Climate change's implications for practice: Pharmacologic considerations of heat-related illness

ABSTRACT

Climate change is the greatest threat to global health. As climate change worsens, heat waves will be longer, more intense, and more frequent. Increased health risks from climate change and heat waves include heat-related illness (HRI). HRI increases ED visits, hospitalizations, and mortality. Healthcare providers should be aware of the impact of medications on risk for HRI. This article elucidates signs and symptoms, populations at risk, drugs and mechanisms that increase risk, and patient education to reduce risk.

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.

Recreational windsurfing-related acute injuries: a narrative review. Part 2: injury prevention and a proposal for a set of potential prevention strategies with a holistic approach

Objective

The purpose of this review was to identify existing prevention strategies for recreational windsurfing-related acute injuries and provide clinicians with a practical overview of current evidence supporting proposed potential prevention strategies.

Methods

A literature search was conducted through March 8, 2023, using relevant keywords with Boolean operators, such as "windsurfing" AND "injury prevention" and "windsurfing" AND "exercise interventions," from the PubMed and Google Scholar databases. Only peer-reviewed English-articles were included.

Results

Existing prevention strategies, right-of-way rules, a new proposed set of eight potential primary to tertiary prevention strategies for windsurfing-related acute injuries, and proposed definitions of injury prevention levels equivalent to Haddon's matrix were identified and tabled.

Conclusions

The proposed potential prevention strategies may facilitate clinicians in preventing recreational windsurfing-related acute injuries. Injury prevention for recreational windsurfing is under-researched. Future studies should focus on large prospective clinical trials evaluating the efficacy of prevention strategies for recreational windsurfing-related injuries.

Remodeling of the cardiovascular hemodynamic environment by lower limb heat exposure: A computational fluid dynamic study

BACKGROUND

Lower limb heat exposure (LLHE) is a promising strategy for the daily management of cardiovascular health because of its non-pharmaceutical advantages. To support the application of this strategy in cardiovascular protection, we examined its impact on the global hemodynamic environment.

METHODS

Skin blood flow (SBF) of eight locations on the lower limbs was measured before and after LLHE (40 °C and 44 °C) in ten healthy subjects by using a laser Doppler flowmeter. A closed-loop model of circulation uses changes in SBF to quantify the influence of LLHE on the blood flow of the arterial trunk (from ascending aorta to the femoral artery) and visceral branches (coronary, celiac, renal, and mesenteric arteries).

RESULTS

The SBF in all locations tested on the lower limbs increased significantly (p<0.001) with LLHE and a 3.39-fold and 7.40-fold increase in mean SBF were observed under 40 °C and 44 °C conditions, respectively. In the model, the peak (3.9-25.1%), end-diastolic (13.7-107.3%), and mean blood flow (8.5-86.5%) in the arterial trunk increased with the increase in temperature, but the retrograde flow in the thoracic aorta and abdominal aorta Ⅰ increased at least twice in the diastolic period. Furthermore, LLHE also increased the blood flow of the visceral branches (2.5-20.7%).

CONCLUSION

These findings suggest that LLHE is expected to be a daily strategy for enhancing the functions of both the arterial trunk and visceral arteries, but the increased blood flow reversal in the thoracic and abdominal aortas warrants further investigation.

Severe Trauma-Induced Coagulopathy: Molecular Mechanisms Underlying Critical Illness

Trauma remains one of the leading causes of death in adults despite the implementation of preventive measures and innovations in trauma systems. The etiology of coagulopathy in trauma patients is multifactorial and related to the kind of injury and nature of resuscitation. Trauma-induced coagulopathy (TIC) is a biochemical response involving dysregulated coagulation, altered fibrinolysis, systemic endothelial dysfunction, platelet dysfunction, and inflammatory responses due to trauma. The aim of this review is to report the pathophysiology, early diagnosis and treatment of TIC. A literature search was performed using different databases to identify relevant studies in indexed scientific journals. We reviewed the main pathophysiological mechanisms involved in the early development of TIC. Diagnostic methods have also been reported which allow early targeted therapy with pharmaceutical hemostatic agents such as TEG-based goal-directed resuscitation and fibrinolysis management. TIC is a result of a complex interaction between different pathophysiological processes. New evidence in the field of trauma immunology can, in part, help explain the intricacy of the processes that occur after trauma. However, although our knowledge of TIC has grown, improving outcomes for trauma patients, many questions still need to be answered by ongoing studies.