Exertional Heat Stroke Research Articles

Exertional heat stroke. Are we cool enough? Retrospective observational study of patients of running events

Exertional heat stroke. Are we cool enough? Retrospective observational study of patients of running events

L-carnitine ameliorates myocardial injury by alleviating endoplasmic reticulum stress via inhibition of PERK pathway in exertional heatstroke rats

L-carnitine ameliorates myocardial injury by alleviating endoplasmic reticulum stress via inhibition of PERK pathway in exertional heatstroke rats

A case of successful pediatric heat stroke treatment using normothermic targeted temperature management

This case report describes a successful use of normothermic targeted temperature management (TTM) for the treatment of a 14-year-old girl with exertional heat stroke. Upon hospitalization, she exhibited a 40.5 ℃ core temperature and multiorgan failure. We immediately applied the TTM, targeting a range of 36-37 ℃. Her condition improved rapidly, with vital signs stabilized and consciousness fully regained by day 3. She experienced a bimodal pattern of rhabdomyolysis during recovery, which was managed without further complications. No neurological sequelae were observed, and all laboratory parameters were normalized before discharge on day 10. This case suggests the potential efficacy of normothermic TTM in pediatric heat stroke.

Effect of different delayed cooling time on organ injuries in rat models of exertional heat stroke

To investigate how the timing of cooling therapy affects organ injuries in rats with exertional heat stroke (EHS) and explore the possible mechanisms. A total of 60 adult male Wistar rat models of EHS were randomized into model group without active cooling after modeling, immediate cooling group with cold water bath immediately after modeling, delayed cooling groups with cold water bath at 5, 15 and 30 min after modeling, with another 12 mice without EHS as the normal control group. The changes in core body temperature of the mice were recorded and the cooling rate was calculated. After observation for 24 h, the mice were euthanized and blood samples were collected for detection of interleukin-1β (IL-1β), IL-2, IL-4, IL-6, IL-10, and interferon-γ, followed by pathological examination of the vital organs. The rats that died within 24 h were immediately dissected for examination. The number of deaths of the model rats within 24 h increased significantly with the time of delay of cooling treatment. The delay of cooling was positively correlated (r=0.996, P=0.004) while the cooling rate negatively correlated with the mortality rate (r=-0.961, P=0.009). The inflammatory cytokine levels presented with different patterns of variations among the cooling intervention groups. All the rat models of EHS had significant organ damages characterized mainly by epithelial shedding, edema, effusion, and inflammatory cell infiltration, and brain and renal injuries reached the peak level at 24 h after EHS. EHS causes significant nonspecific pathologies of varying severities in the vital organs of rats, and the injuries worsen progressively with the delay of cooling. There is a significant heterogeneity in changes of serum inflammatory cytokines in rats with different timing of cooling intervention following EHS.

A case of acute pulmonary edema caused by exertional heat stroke

This paper reports a case of acute pulmonary edema caused by exertional heat stroke due to imbalance of body heat production and heat dissipation caused by high intensity military training physical activities. The patient's lesions developed rapidly and pulmonary edema progressed rapidly and diffusingly. After early identification, active invasive mechanical ventilation and hormone therapy, the pulmonary imaging lesions of pulmonary edema were rapidly absorbed, and the dyspnea was improved. This article discusses the incidence, imaging features and treatment of acute pulmonary edema caused by exertional heat stroke, and provides reference for clinical diagnosis and treatment.

Athletic training students’ experiences and perceptions of exertional heat stroke simulated encounters: A qualitative analysis

Introduction: Athletic trainers are trained to recognize exertional heat stroke (EHS), which is critical to implementing lifesaving measures. Rectal thermometry is the best practice for recognizing EHS, and the Commission on Accreditation of Athletic Training Education (CAATE) requires students to learn rectal thermometry. Rooted in transformative learning theory, this study explored the perceptions and experiences of athletic training students following simulated EHS encounters with either high-fidelity (HF) simulators or standardized patients (SPs). Methods: This was a qualitative study using phenomenological theory. Through semi-structured qualitative interviews, we explored participants' personal experiences and perceptions following their simulation interventions. Participants included sixteen first-year Master of Athletic Training students (HF=8, SP=8; 4 males and 4 females in each group) ages 21-38 (23.69±4.48) who were enrolled in a course discussing exertional heat illnesses. Data Analysis: We recorded and transcribed the interviews verbatim. We used qualitative software, Nvivo (Denver, CO), to categorize the data into themes and codes. To ensure trustworthiness, we used member checking and investigator triangulation. Results: Three themes emerged from the data: 1) Simulation environment, 2) Mindset shifts, and 3) Perceptions of other simulation types. Participants from both groups described positive learning experiences in a foreign yet low stakes learning environment emphasizing repetition for learning the skill. The HF group shared beneficial aspects of patient-history-taking opportunities. The SP group shared the benefits and applicability of developing a patient-provider relationship through communicating with their SP. Most participants from both groups could immerse themselves in the encounter for a realistic experience. Both groups discussed how their mindset towards EHS and rectal thermometry changed after their encounter. Lastly, both groups agreed their simulation intervention was superior to practicing on a task trainer. Conclusions: Instructors of athletic training programs should strive to implement realistic simulated encounters for emergency skills training of athletic training students. A safe space for learning in a low-stakes environment should be fostered. Based on the shared perceived benefits of SP encounters for building provider-patient rapport and feedback opportunities, instructors should consider implementing SPs throughout their curriculum.

Sex Differences In Biomarkers Of End-organ Damage In Exertional Heat Stroke

Sex Differences In Biomarkers Of End-organ Damage In Exertional Heat Stroke

The Pattern Of Change In Blood Biomarkers In Exertional Heat Stroke Patients During Hospitalization

The Pattern Of Change In Blood Biomarkers In Exertional Heat Stroke Patients During Hospitalization

35P Generation of a zebrafish knock-in model of exertional heat stroke

35P Generation of a zebrafish knock-in model of exertional heat stroke

ANP Improves The Water And Salt Metabolism During Cooling Treatment For Exertional Heat Stroke

ANP Improves The Water And Salt Metabolism During Cooling Treatment For Exertional Heat Stroke

Sex differences in biomarkers of end-organ damage following exertional heat stroke in humans.

Women are participating in military and athletic activities in the heat in increasing numbers, but potential sex differences in sequelae from exertional heat illness remain poorly understood. We tested the hypothesis that women suffering from exertional heat stroke (EHS) would have similar severity of organ damage biomarkers compared with men, as measured in a hospital setting. We studied women and men presenting with EHS to the emergency department at Fort Moore, GA. We measured creatinine (CR), creatine kinase (CK), alanine-transaminase (ALT), aspartate aminotransferase (AST), and estimated glomerular filtration rate (eGFR). Core temperature was also assessed by medical personnel. Biomarker data were obtained for 62 EHS cases (11 women). Men were significantly taller, and heavier, and had larger body mass index (BMI) and body surface area (P < 0.05 for all). The highest recorded body core temperature was not different between groups [women: 41.11°C (40.06, 41.67); men: 41.11°C (40.28, 41.72), P = 0.57]. Women had significantly lower peak CR [women: 1.39 (1.2, 1.48) m·dL-1; men: 1.75 (1.53, 2.16) mg·dL-1, P < 0.01] and peak CK [women: 584 (268, 2,412) U·L-1; men: 2,183 (724, 5,856) U·L-1, P = 0.02]. Peak ALT and AST were not different between groups; during recovery time points, ALT and AST were either similar or lower in women. Women spent approximately half as much time in the hospital following admittance compared with men. Our findings suggest that women may be less susceptible to organ injury resulting from EHS. Further research is necessary to understand the pathophysiology underlying these differences and how biomarkers of end-organ damage severity can differ between women and men following EHS.NEW & NOTEWORTHY We studied otherwise healthy women and men after exertional heat stroke in a military training environment. Peak values for biomarkers of kidney and muscle damage were lower in women compared with men despite similar (highest recorded) body core temperatures. During recovery, organ damage markers were similar or lower in women. These sex differences may indicate differences in the pathophysiology of responses, but more work is needed to clarify specific mechanisms.

Overexpression of Parkin promotes the protective effect of mitochondrial autophagy on the lung of rats with exertional heatstroke

BackgroundThe roles of the Pink1/Parkin pathway and mitophagy in lung injury during heat stroke remain unclear. In this study, we investigated the role of Pink1/Parkin-mediated mitophagy in acute lung injury (ALI) in rats with exertional heat stroke (EHS). MethodsSixty Sprague Dawley rats were randomly divided into control (CON), control + Parkin overexpression (CON + Parkin), EHS, and EHS + Parkin overexpression (EHS + Parkin) groups. Parkin was overexpressed by injecting an adeno-associated virus carrying the Parkin gene into the tail vein, and a rat model of EHS was established. Pathological changes in the lung tissue were analyzed using microcomputed tomography (micro-CT), and the lung coefficient and pulmonary capillary permeability were measured. Enzyme-linked immunosorbent assay were used to determine the levels of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α, and reactive oxygen species. The morphology of mitochondria in type Ⅱ epithelial cells of lung tissue was observed using transmission electron microscopy; and the apoptosis of lung tissue, the level of mitophagy, and the co-localization of Pink1 and Parkin were determined using immunofluorescence. The expression of Pink1, Parkin, mitofusin-2 (MFN2), phosphatase and tensin homolog (PTEN), PTEN-L, p62, and the autophagy marker microtubule-associated protein 1 light chain 3 (LC3) in rat lung tissue was measured by western blotting, and the ratio of LC3II/LC3I was calculated. ResultsCompared with the EHS group, the survival rate of rats in the EHS + Parkin group was significantly higher. Their lung coefficient and pulmonary vascular permeability decreased and the pathological changes were significantly alleviated (P <0.05). Their levels of inflammatory factors and reactive oxygen species were significantly decreased (P <0.05), and the degree of mitochondrial swelling in pulmonary type II epithelial cells was alleviated. The apoptosis of lung tissue was alleviated, the colocalization of Pink1 and Parkin, LC3 and Tom20 was enhanced, and the ratio of LC3-II/LC3-I increased. The expression of Pink1, MFN2, PTEN-L, and p62 decreased, whereas the expression of PTEN was not significantly different than that of the EHS group (P >0.05). ConclusionPink1/Parkin-mediated mitophagy dysfunction is one of the mechanisms underlying ALI in rats with EHS, and activation of Parkin overexpression-mediated mitophagy can alleviate ALI caused by EHS.

Hyperthermia and Exertional Heatstroke During Running, Cycling, Open Water Swimming, and Triathlon Events.

Few previous epidemiological studies, sports medicine position statements, and expert panel consensus reports have evaluated the similarities and differences of hyperthermia and exertional heatstroke (EHS) during endurance running, cycling, open water swimming, and triathlon competitions. Accordingly, we conducted manual online searches of the PubMed and Google Scholar databases using pre-defined inclusion criteria. The initial manual screenings of 1192 article titles and abstracts, and subsequent reviews of full-length pdf versions identified 80 articles that were acceptable for inclusion. These articles indicated that event medical teams recognized hyperthermia and EHS in the majority of running and triathlon field studies (range, 58.8 to 85.7%), whereas few reports of hyperthermia and EHS appeared in cycling and open water swimming field studies (range, 0 to 20%). Sports medicine position statements and consensus reports also exhibited these event-specific differences. Thus, we proposed mechanisms that involved physiological effector responses (sweating, increased skin blood flow) and biophysical heat transfer to the environment (evaporation, convection, radiation, and conduction). We anticipate that the above information will help race directors to distribute pre-race safety advice to athletes and will assist medical directors to better allocate medical resources (eg, staff number and skill sets, medical equipment) and optimize the management of hyperthermia and EHS.

Protection of Parkin over-expression on lung in rats with exertional heat stroke by activating mitophagy

ObjectiveTo investigate the role of Parkin overexpression-induecd mitophagy in alleviating acute lung injury of exertional heat stroke(EHS) rats.MethodsEighty SD rats were divided into four groups: Control group (CON group), Control Parkin overexpression group (CON + Parkin group), exertional heat stroke group (EHS group), and exertional heat stroke Parkin overexpression group (EHS + Parkin group). Adeno-associated virus carrying the Parkin gene was intravenously injected into the rats to overexpress Parkin in the lung tissue. An exertional heat stroke rat model was established, and survival curves were plotted. Lung Micro-CT was performed, and lung coefficient and pulmonary microvascular permeability were measured. Enzyme-linked immunosorbent assays(ELISA) were used to determine the levels of interleukin-6(IL-6), interleukin-1β(IL-1β), Tumor necrosis factor-α(TNF-α), and reactive oxygen species(ROS). The morphology of mitochondria in type II epithelial cells of lung tissue was observed using transmission electron microscopy. The apoptosis of lung tissue, the level of mitophagy, and the co-localization of Pink1 and Parkin were determined using immunofluorescence. The expression of Pink1, Parkin, MFN2, PTEN-L, PTEN, p62, and microtubule associated protein 1 light chain 3 (LC3) in rat lung tissue was measured by western blot.ResultsCompared with the CON group, there were more severe lung injury and more higher levels of IL-6, IL-1β, TNF-α in EHS rats. Both of the LC3-II/LC3-I ratio and the co-localization of LC3 and Tom20 in the lung tissue of EHS rats decreased. Compared with the EHS group, the survival rate of rats in the EHS + Parkin overexpression group was significantly increased, lung coefficient and pulmonary microvascular permeability were reduced, and pathological changes such as exudation and consolidation were significantly alleviated. The levels of IL-6, IL-1β, TNF-α, and ROS were significantly decreased; the degree of mitochondrial swelling in type II alveolar epithelial cells was reduced, and no vacuolization was observed. Lung tissue apoptosis was reduced, and the colocalization fluorescence of Pink1 and Parkin, as well as LC3 and Tom20, were increased. The expression of Parkin and LC3-II/LC3-I ratio in lung tissue were both increased, while the expression of P62, Pink1, MFN2, and PTEN-L was decreased.ConclusionPink1/Parkin-mediated mitophagy dysfunction is one of the mechanisms underlying acute lung injury in rats with EHS, and activation of Parkin overexpression induced-mitophagy can alleviate acute lung injury caused by EHS.

Rebound Hyperthermia in Exertional Heat Stroke.

Exertional heat stroke (EHS) is a life-threatening condition requiring rapid reversal of hyperthermia to prevent poor health outcomes. Current treatment protocols aim for a cooling rate of 0.15 C/min using various modalities. This case report details a 22-year-old male who, despite initial successful cooling measures, experienced rebound hyperthermia, necessitating the use of endovascular cooling (EVC). The patient collapsed during a 19.3 km (12-mile) ruck march in Fort Moore, Georgia, with an initial core temperature of 41.6ºC. Conventional cooling methods, including ice sheets and chilled intravenous saline, adequately cooled the patient to target temperatures; however, discontinuation of cooling methods resulted in rebound hyperthermia. Endovascular cooling was eventually initiated, resulting in euthermia after 36 hours of continued use. During his hospital admission, the patient was evaluated thoroughly for underlying etiologies contributing to his rebound hyperthermia. This workup did not yield any concerning pathology, except for bilateral foot cellulitis noted on physical examination, which was subsequently managed with antibiotics. Despite initial complications, the patient recovered within 5 days and returned to duty after 2 months. Several case reports have been published regarding the use of EVC in the management of EHS. These reports, however, describe its use in initial management of EHS or in cases where hyperthermia was refractory to other conventional cooling methods. To our knowledge, this is the first report of its kind highlighting its successful implementation in rebound hyperthermia. Early recognition and initiation of cooling measures are critical in EHS cases. Future directions include developing EHS-specific EVC protocols for patients experiencing refractory or rebound hyperthermia.

APTT and D-dimer as biomarkers for heatstroke in patients with severe heat-related illnesses.

The objective of this study was to analyze the changes of activated partial thromboplastin time (APTT) and D-dimer in severe heatstroke (HS) patients and their value in identifying HS patients and to analyze clinical features and early laboratory test results of heat-related illnesses. Forty-five patients with heat-related illnesses who were admitted to the Department of Emergency and Intensive Care Medicine of Suining Central Hospital from June 2022 to April 2023 were retrospectively analyzed. Patients were divided into 3 groups based on their clinical diagnosis: classic HS group, exertional HS group, and control group. General date and laboratory test results were collected, especially APTT and D-dimer. The receiver operating characteristic curve was used to analyze D-dimer and APTT. : There were differences in gender distribution among the 3 groups. Exertional HS was dominated by male patients, and classic HS was dominated by elderly patients. Binary logistic regression analysis of coagulation index showed a significant correlation between D-dimer and APTT and HS. The receiver operating characteristic curve results showed that APTT and D-dimer had high sensitivity and specificity in the identification of HS with an area under the curve (AUC) of 0.846, sensitivity of 97%, and specificity of 58.3% for APTT and an AUC of 0.861, sensitivity of 72%, and specificity of 91.7% for D-dimer (D-dimer + APTT [AUC, 0.929; sensitivity, 81.8%-91.7%; P < .001]). : The mortality rate of HS is high, and early diagnosis is particularly important. APTT and D-dimer may be used as markers assisting in identifying HS.

Core Temperature Response to Cold Water Immersion in Heat Stroke Patients Is Non-Linear and Unrelated to Sex or Body Size.

Cold water immersion (CWI) is the most effective treatment for exertional heat stroke (EHS). However, knowledge on core temperature response during CWI treatment and the relation with patient characteristics (i.e., sex, anthropometrics) is limited. Therefore, the current study aimed to examine the core temperature response (in °C) during CWI treatment of recreational athletes participating in large running events and investigate the impact of sex and anthropometric characteristics on the cooling rate (in °C/min). This observational study includes 57 athletes (n = 22 females; 39%) who suffered from EHS during an exercise event in the Netherlands. After admission to the medical facilities, a rectal temperature (Trec) probe was inserted and all clothing was removed before immersion in an ice bath (6.4 ± 1.6 °C). Rectal temperature was continuously measured throughout treatment, and treatment was continued until Trec ≤ 38.9 °C, or based on the decision of the emergency physician. Initial Trec did not differ between males (41.3 ± 0.9 °C) and females (41.2 ± 0.8 °C, p = 0.83). A non-linear response to CWI was observed, with the decrease in Trec beginning after 6 minutes of CWI. The decrease in Trec did not differ between both sexes (ptime*sex = 0.96). The cooling rate did not differ between males (0.21 ± 0.15 °C/min) and females (0.19 ± 0.08 °C/min, p = 0.55), and was not related to body mass, body surface area and body surface area to mass ratio (all p-values >0.05). We demonstrated that the cooling rate during CWI did not differ between men and women suffering from EHS, and that the Trec response to CWI is non-linear and not dependent on anthropometric characteristics. This suggests that no sex differentiation is needed in the EHS treatment guidelines and confirms the necessity to continuously monitor Trec during treatment.

Heat acclimation alleviates the heat stress-induced impairment of vascular endothelial cells

Heat acclimation (HA) is found to help decrease the incidence of heat-related illnesses such as heat syncope and exertional heat stroke. However, the response of vascular endothelial cells to HA remain to be elucidated. In this study, mouse brain microvascular endothelial cells (bEnd.3), human umbilical vein endothelial cells (HUVEC), and human aortic endothelial cells (HAEC) were selected. The cells were first subjected to HA at 40 ℃ for 2 h per day for 3 days, and then subjected to heat stress at 43 ℃ for 2 h or 4 h. After heat stress, HA-pretreated cells showed a significant increase in cell viability, cell integrity, a decrease in the proportion of S phase cells, cell apoptosis, and cytoskeletal shrinkage compared with the cells without HA pretreatment. Additionally, the expression of VEGF, ICAM-1, iNOS and EPO in HA-pretreated cells significantly increased. We also presented evidence that HA upregulated HSP70 and bcl-2, while downregulated p-p53 and bax. Notably, the suppression of HSP70 expression attenuated the protective role of heat acclimation. Furthermore, HA mitigated injuries in vital organs of mice exposed to heat stress. Conclusively, these findings indicated the HA can increase the vitality of vascular endothelial cells after heat stress, partially restore the function of vascular endothelial cells, and this protective effect may be related to the upregulation of HSP70 expression.

Cardiovascular magnetic resonance feature tracking derived strain analysis can predict return to training following exertional heatstroke

BackgroundExertional heatstroke (EHS) is increasingly common in young trained soldiers. However, the prognosis marker in EHS patients remains unclear. To evaluate cardiac MRI feature tracking (CMR-FT) derived left ventricle (LV) strain as a biomarker for return to training (RTT) in trained soldiers with EHS in a prospective CMR cohort. MethodsTrained soldiers (participants) with EHS underwent cardiac MR cine sequences between June 2020 and August 2023. Two-dimensional (2D) LV strain parameters were derived. At 3 months after index CMR, the participants with persistent cardiac symptoms including chest pain, dyspnea, palpitations, syncope, and recurrent heat-related illness were defined as non-RTT. Multivariable logistic regression analysis is used to develop a predictive RTT model. The performance of different models was compared using the area under curve (AUC). ResultsA total of 80 participants (median age, 21 years; interquartile range (IQR), 20-23 years) and 27 health controls (median age, 21 years; IQR, 20-22 years) were prospectively included. Of the 77 participants, 32 (41.6%) had persistent cardiac symptoms and were not able to RTT at 3 months follow-up after experiencing EHS. The 2D global longitudinal strain (GLS) was significantly impaired in EHS participants compared to the healthy control group (-15.81 ± 1.67% vs -16.93 ± 1.22%, P =.001), which also showed significantly statistical differences between participants with RTT and non-RTT (-14.99 ± 3.54% vs -16.53 ± 1.43%, P <.001). 2D-GLS (≤ -15.00%) (odds ratio, 1.53; 95% confidence interval (CI): 1.08, 2.17; P =.016) was an independent predictor for RTT even after adjusting known risk factors. 2D-GLS provided incremental prognostic value over the clinical model and conventional CMR parameters model (AUCs: 0.72 vs 0.88, P =.013; 0.79 vs 0.88, P =.023; respectively). ConclusionsTwo-dimensional global longitudinal strain (≤ -15.00%) is an incremental prognostic CMR biomarker to predict return to training in exertional heatstroke soldiers.

Suspected exertional heat stroke; A case study of worker cooling in a hot and humid field environment.

In the event of a severe occupational heat-related illness, paramedic assistance may not be immediately available. A worker's survival may depend on their co-workers access to efficacious field-based cooling modalities. One cooling method that has been claimed to be practical in field-based settings is the ice towel method. This case study assessed the practicality of the ice towel method in an industrial setting, where criteria for use include cost effectiveness, portability, scalability, and implementation by a single worker under the stress of an emergency. This case study describes the emergency application of the ice towel method while awaiting paramedics, for a worker suffering suspected exertional heat stroke on a remote job site. Ice towels were able to be transported to a remote field site and applied successfully by a single worker under the stress of a potentially life-threatening emergency. The ice towel method was cost effective, scalable, transportable, and rapidly applied in a field-based emergency. This case study demonstrates the importance of organizations assessing their heat-related risks, and determining controls based upon their efficacy and practicality for their unique setting.