Approach to heat-related illness.

OBJECTIVE: To describe heat-related illness and provide approaches for treatment in family practice. SOURCES OF INFORMATION: The MeSH terms heat-related illness and primary care were searched in PubMed. Clinical trials, practice reviews, and systematic reviews were included in this review. Reference lists were reviewed for additional articles. MAIN MESSAGE: Extreme heat events are increasing in frequency due to climate change and can directly result in heat exhaustion, heat stroke, or death. Exposure to extreme heat also exacerbates underlying health conditions. Patients may be at increased risk of heat-related illness because of underlying sensitivity to heat, increased exposure to heat, or barriers to resources. CONCLUSION: Family physicians can help prevent heat-related illness by identifying and counselling patients who are at increased risk and by advocating for interventions that reduce the chance of heat-related illness.

IOC consensus statement on recommendations and regulations for sport events in the heat.

This document presents the recommendations developed by the IOC Medical and Scientific Commission and several international federations (IF) on the protection of athletes competing in the heat. It is based on a working group, meetings, field experience and a Delphi process. The first section presents recommendations for event organisers to monitor environmental conditions before and during an event; to provide sufficient ice, shading and cooling; and to work with the IF to remove regulatory and logistical limitations. The second section summarises recommendations that are directly associated with athletes' behaviours, which include the role and methods for heat acclimation; the management of hydration; and adaptation to the warm-up and clothing. The third section explains the specific medical management of exertional heat stroke (EHS) from the field of play triage to the prehospital management in a dedicated heat deck, complementing the usual medical services. The fourth section provides an example for developing an environmental heat risk analysis for sport competitions across all IFs. In summary, while EHS is one of the leading life-threatening conditions for athletes, it is preventable and treatable with the proper risk mitigation and medical response. The protection of athletes competing in the heat involves the close cooperation of the local organising committee, the national and international federations, the athletes and their entourages and the medical team.

[Expert consensus on the prevention and treatment of heatstroke in children (2023)]. / å„¿ç«¥ä¸­æš‘çš„é˜²æ²»æ–¹æ¡ˆä¸“å®¶å ±è¯†ï¼ˆ2023年）.

Due to the immature development of temperature regulation in the central nervous system, children have a weakened ability to regulate heat and are susceptible to heatstroke, which can lead to organ damage. Based on the evidence evaluation criteria of the Oxford Centre for Evidence-Based Medicine, this expert consensus group evaluated the current evidence on heatstroke in children, and formed this consensus through thorough discussion with the aim of providing reference for the prevention and treatment of heatstroke in children. This consensus includes classifications, pathogenesis, prevention measures, as well as pre-hospital and in-hospital treatment plans for heatstroke in children.

An Advanced Internet of Things System for Heatstroke Prevention with a Noninvasive Dual-Heat-Flux Thermometer.

Heatstroke is a concern during sudden heat waves. We designed and prototyped an Internet of Things system for heatstroke prevention, which integrates physiological information, including deep body temperature (DBT), based on the dual-heat-flux method. A dual-heat-flux thermometer developed to monitor DBT in real-time was also evaluated. Real-time readings from the thermometer are stored on a cloud platform and processed by a decision rule, which can alert the user to heatstroke. Although the validation of the system is ongoing, its feasibility is demonstrated in a preliminary experiment.

[Chinese foreign medical aid work should pay attention to heat stroke as a preventable disease under global warming context].

Within the global warming context, heat stroke heavily threatens human health as the most severe type of heat-related illnesses. Despite the urgent onset, severe condition and poor prognosis, heat stroke is entirely preventable and treatable. Most of the recipient countries of Chinese foreign medical aid work are concentrated in the tropical and subtropical regions. It is necessary to popularize the knowledge of heat stroke and improve the ability of diagnose and treatment among foreign medical aid members, which is critical to enhance the quality of medical service and provide better medical care for recipient countries and workers in Chinese-funded institutions. This article reviews the latest research progress in the epidemiology, pathophysiology, diagnosis, and treatment of heat stroke to provide scientific reference for actively implementing interventions and reducing morbidity and mortality.

Exertion-Related Illness: The Critical Roles of Leadership and Followership.

Exertion-related illness (ERI), despite aggressive efforts with both prevention and emergency action planning, continues to be a considerable threat to both athletes and warfighters. Numerous case reports and series have served to elucidate risk factors, which have in turn become the focus of prevention strategies. While this approach has assisted in mitigating athlete risk, recent institutional guidance has identified the need for greater protection of athletes by accountability of training programs and the recognition of periods of distinct athlete vulnerability. These recommendations, in addition to observations from lessons learned from the aforementioned cluster reports of ERI, have a strong call-out for the role of leadership as both a culprit for injury and a potential mechanism for prevention. This commentary introduces a leader-follower framework and explores this model in the evolution of ERI and offers recommendations as to how we move forward toward making progress in prevention.

Diagnosis and Management of Heatstroke.

Heatstroke is a life-threatening  and the most severe form of heat-related illnesses, characterized by body temperature >40ºC and central nervous system dysfunction. Heatstroke is classified into Non-Exertional Heatstroke (NEHS) and Exertional Heatstroke (EHS). The pathophysiology of heatstroke involves a combination of direct heat effects on the host, the systemic inflammatory and coagulopathic response. The diagnosis of heatstroke based on Bouchama's definition or Japan Association of Acute Medicine (JAAM) criteria. The basic principle of heatstroke management is early resuscitation and immediate cooling. Cold water immersion or convection evaporation method can be implemented based on the specific patient characteristic. Preventive strategies are early recognition by health workers, socialization to vulnerable groups and adequate acclimatization.

Precooling's Effect on American Football Skills.

Bradley, LJ, Miller, KC, Wiese, BW, and Novak, JR. Precooling's effect on American football skills. J Strength Cond Res 33(10): 2616-2621, 2019-Precooling (i.e., cooling before exercise) may reduce the risk of exertional heatstroke (EHS) in American football athletes. However, implementation of precooling by coaches or medical staff would likely be poor if it impaired performance. We investigated whether precooling impacted American football skill performance in this randomized, crossover, counterbalanced study. Twelve men (24 ± 2 years, mass = 85.5 ± 6.3 kg, height = 181.8 ± 8.1 cm) completed a familiarization day to practice each skill and then 2 testing days. On testing days (wet-bulb globe temperature = 19.3 ± 4.1° C), subjects were either precooled for 15 minutes using cold-water immersion (10.1 ± 0.3° C) or not (control). Then, they donned an American football uniform and completed several bouts of 8 different football skills. Rectal temperature (Trec) was measured before, during, and after skill testing. Precooling did not affect vertical jump, broad jump, agility, dynamic or stationary catching, or maximum throwing distance (p ≥ 0.13). Precooling impaired 40-yard dash time (precooling = 5.72 ± 0.53 seconds, control = 5.31 ± 0.34 seconds; p = 0.03, effect size = 1.2) and throwing accuracy (precooling = 4 ± 1 points, control = 7 ± 2 points; p = 0.001, effect size = 1.4). On average, Trec was 0.58 ± 0.35° C lower during skills testing after precooling and statistically differed from control from minute 10 to the end of testing (∼35 minutes; p < 0.05, effect size ≥ 1.2). Precooling may be a useful EHS prevention strategy in American football players because it lowered Trec without impacting most skills. By lowering Trec, precooling would prolong the time it would take for an athlete's Trec to become dangerous (i.e., >40.5° C). If precooling is implemented, coaches should alter practice so that throwing accuracy and speed drills occur after an athlete's Trec returns to normal (i.e., >35 minutes).

Exertional Heat Stroke within Secondary School Athletics.

Exertional heat stroke (EHS) remains one of the leading causes of sudden death in sport despite clear evidence showing 100% survivability with the proper standards of care in place and utilized. Of particular concern are student athletes competing at the secondary school level, where the extent of appropriate health care services remains suboptimal compared with organized athletics at the collegiate level and higher. While rapid recognition and rapid treatment of EHS ensures survival, the adoption and implementation of these lifesaving steps within secondary school athletics warrant further discussion within the sports medicine community. Establishing proper policies regarding the prevention and care of EHS coupled with utilizing an interdisciplinary care approach is essential for 1) minimizing risk and 2) guaranteeing optimal outcomes for the patient.

Heat balance model for a human body in the form of wet bulb globe temperature indices.

The purpose of this study is to expand the empirically derived wet bulb globe temperature (WBGT) index to a rational thermal index based on the heat balance for a human body. We derive the heat balance model in the same form as the WBGT for a human engaged in moderate intensity work with a metabolic heat production of 174W/m2 while wearing typical vapor-permeable clothing under shady and sunny conditions. Two important relationships are revealed based on this derivation: (1) the natural wet bulb and black globe temperature coefficients in the WBGT coincide with the heat balance equation for a human body with a fixed skin wettedness of approximately 0.45 at a fixed skin temperature; and (2) the WBGT can be interpreted as the environmental potential to increase skin temperature rather than the heat storage rate of a human body. We propose an adjustment factor calculation method that supports the application of WBGT for humans dressed in various clothing types and working under various air velocity conditions. Concurrently, we note difficulties in adjusting the WBGT by using a single factor for humans wearing vapor-impermeable protective clothing. The WBGT for shady conditions does not need adjustment depending on the positive radiant field (i.e., when a radiant heat source exists), whereas that for the sunny condition requires adjustments because it underestimates heat stress, which may result in insufficient human protection measures.

Protection of intestinal injury during heat stroke in mice by interleukin-6 pretreatment.

KEY POINTS: Heat stroke afflicts thousands of humans each year, worldwide. The immune system responds to hyperthermia exposure resulting in heat stroke by producing an array of immunological proteins, such as interleukin-6 (IL-6). However, the physiological functions of IL-6 and other cytokines in hyperthermia are poorly understood. We hypothesized that IL-6 plays a protective role in conditions of heat stroke. To test this, we gave small IL-6 supplements to mice prior to exposing them to hot environments sufficient to induce conditions of heat stroke. Pretreatment with IL-6 resulted in improved ability to withstand heat exposure in anaesthetized mice, it protected the intestine from injury, reducing the permeability of the intestinal barrier, and it attenuated the release of other cytokines involved in inflammation. The results support the hypothesis that IL-6 is a 'physiological stress hormone' that plays an important role in survival during acute life-threatening conditions such as heat stroke. ABSTRACT: The role of interleukin-6 (IL-6) in hyperthermia and heat stroke is poorly understood. Plasma IL-6 is elevated following hyperthermia in animals and humans, and IL-6 knockout mice are more intolerant of severe hyperthermia. We evaluated the effect of IL-6 supplementation on organ injury following severe hyperthermia exposure in anaesthetized mice. Two hours prior to hyperthermia, mice were treated with 0.6 µg intraperitoneal IL-6, or identical volumes of saline in controls. Mice were anaesthetized, gavaged with FITC-dextran for measures of gastrointestinal permeability, and exposed to incremental (0.5°C every 30 min) increases in temperature. Heating stopped when maximum core temperature (Tc) of 42.4°C was attained (Tc,max). The mice recovered at room temperature (≈22°C) for 30 or 120 min, at which time plasma and tissues were collected. IL-6-treated mice, on average, required ≈25 min longer to attain Tc,max . Injury and swelling of the villi in the duodenum was present in untreated mice after 30 min of recovery. These changes were blocked by IL-6 treatment. IL-6 also reduced gastrointestinal permeability, assayed by the accumulation of FITC-dextran in plasma. Plasma cytokines were also attenuated in IL-6-treated animals, including significant reductions in TNFα, MCP-1 (CXCL2), RANTES (CCL5) and KC (CCL5). The results demonstrate that IL-6 has a protective influence on the pattern of physiological responses to severe hyperthermia, suggesting that early endogenous expression of IL-6 may provide a protection from the development of organ damage and inflammation.

Dietary nitrate reduces the O2 cost of desert marching but elevates the rise in core temperature.

PURPOSE: Dietary nitrate (NO3 (-)) supplementation reduces the O2 cost of fixed-workload tasks performed in temperate environments but has not been examined in the heat. If this effect were retained it could reduce heatstroke risk in military personnel that are deployed for desert combat. METHODS: Nine men completed three 45 min loaded battle marches at a standard cadence (4.83 km h(-1)/1.5 % grade) while wearing full combat gear [BDU, boots, body armor (8 kg), NBC suit] and carrying a loaded rucksack (16 kg). The 1st March (FAM) commenced in a temperate environment. The 2nd and 3rd commenced in simulated dry desert conditions (41 °C/20 % RH) and required subjects to ingest the beetroot juice equivalent of 8.4 mmol NO3 (-) (BRJ) or a NO3 (-) depleted placebo (PLA) for 6 days prior. VO2, VCO2, V E, core (T re), skin (T sk), and mean body (T b) temperatures, HR, and physiological strain index (PSI) were measured continuously. Thermal sensation, generalized discomfort, and perceived exertion (RPE) were measured at 5 min intervals. Heat storage (HS) was calculated. Blood markers of gastrointestinal permeability (TNF, Il-6, HO-1) were measured before and after exercise. RESULTS: VO2 in BRJ was lower than PLA from 1 to 12; 16 to 26; and 29 to 45 min of exercise (p < 0.05). VCO2 in BRJ was lower than PLA from 1 to 12 min (p < 0.05). V E in BRJ was lower than PLA from 1 to 20 min of exercise (p < 0.05). T re and T b in BRJ exceeded PLA from 16 to 45 min (p < 0.05). TNF, Il-6, and HO-1 were reduced in BRJ (p < 0.05) while HR, PSI, Tsk, and HS were not altered (p > 0.05). Thermal sensation, generalized discomfort, and RPE were elevated in BRJ from 40 to 45, 25 to 45, and 10 to 45 min, respectively (p < 0.01). CONCLUSION: Metabolic efficiency was improved in BRJ. Paradoxically, body temperatures rose more. This was not due to gut permeability. Therefore, we speculate that based on elimination of other possibilities, blood redistribution from skin to skeletal muscle may have contributed to impaired heat exchange.

Medical Evaluation for Exposure Extremes: Heat.

Exertional heat illness can be a serious consequence of sports or exercise in hot environments. Participants can possess intrinsic or face extrinsic risk factors that may increase their risk for heat-related illness. Knowledge of the physiology and pathology of heat illness, identification of risk factors, and strategies to combat heat accumulation will aid both the practitioner and the participant in preparing for activities that occur in hot environments. Through preparation and mitigation of risk, safe and enjoyable wilderness adventure can be pursued.

Heat stroke during treatment with olanzapine, trihexyphenidyl, and trazodone in a patient with schizophrenia.

OBJECTIVE: Heat stroke is a medical emergency. Psychiatric patients are particularly susceptible to heat stroke. Therefore, awareness and preventive measures of heat stroke are important for both clinicians and patients. Case description A 49-year-old man with schizophrenia, who was under maintenance treatment with olanzapine 20 mg/day, trihexyphenidyl 4 mg/day, and trazodone 50 mg/day, suffered from heat stroke in a heat wave and required intensive care. He recovered with the medical treatment provided. Discussion Several factors could have contributed to the impaired thermoregulation and the occurrence of heat stroke in this case: schizophrenia, the psychotropic regimen, and lack of preventive measures. Possible differential diagnoses of heat stroke in this case include infection, neuroleptic malignant syndrome, and serotonin syndrome. CONCLUSION: Heat stroke can occur during the maintenance treatment of olanzapine, trihexyphenidyl, and trazodone for schizophrenia. Clinicians should be proactive to reduce the risk of heat stroke in psychiatric patients.

Characteristics of elderly people living in non-air-conditioned homes.

The present study aimed to clarify the characteristics of elderly people living in non-air-conditioned homes. A questionnaire survey conducted in Misato city in July 2013 revealed that 96.1% of elderly individuals lived in air-conditioned homes. Elderly individuals living without air conditioners tended to be men, and those who were unmarried, living alone, or living in an apartment. The results suggest that most elderly individuals without air conditioners lived in multi-unit apartments.