Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Heat-Related Illness

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update

The Wilderness Medical Society (WMS) convened an expert panel in 2011 to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. The current panel retained 5 original members and welcomed 2 new members, all of whom collaborated remotely to provide an updated review of the classifications, pathophysiology, evidence-based guidelines for planning and preventive measures, and recommendations for field- and hospital-based therapeutic management of heat illness. These recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks or burdens for each modality. This is an updated version of the WMS clinical practice guidelines for the prevention and treatment of heat illness published in Wilderness & Environmental Medicine. 2019;30(4):S33-S46.

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

Hyperthermia is an internal body temperature increase above 40.5 °C; normally internal body temperature is kept constant through natural homeostatic mechanisms. Heat-related illnesses occur due to exposure to high environmental temperatures in conditions in which an organism is unable to maintain adequate homeostasis. This can happen, for example, when the organism is unable to dissipate heat adequately. Heat dissipation occurs through evaporation, conduction, convection, and radiation. Heat disease exhibits a continuum of signs and symptoms ranging from minor to major clinical pictures. Minor clinical pictures include cramps, syncope, edema, tetany, and exhaustion. Major clinical pictures include heatstroke and life-threatening heat stroke and typically are expressed in the presence of an extremely high body temperature. There are also some categories of people at greater risk of developing these diseases, due to exposure in particular geographic areas (e.g., hot humid environments), to unchangeable predisposing conditions (e.g., advanced age, young age (i.e., children), diabetes, skin disease with reduced sweating), to modifiable risk factors (e.g., alcoholism, excessive exercise, infections), to partially modifiable risk factors (obesity), to certain types of professional activity (e.g., athletes, military personnel, and outdoor laborers) or to the effects of drug treatment (e.g., beta-blockers, anticholinergics, diuretics). Heat-related illness is largely preventable.

Investigating city bike rental usage and wet-bulb globe temperature

Extreme heat exacerbates human illness and constrains the intensity and/or duration of outdoor activities. Temperature is an incomplete metric of outdoor heat exposures. By contrast, Wet Bulb Globe Temperature (WBGT) is a heat exposure metric that considers air temperature, moisture, solar radiation, and wind speed. In the USA, bicycle activity increased by 60% from 2000 to 2010. Several studies examined weather conditions and bicycling activities. However, few studies examined how the public should conduct their daily physical activities per weather conditions.This study investigated the relationship between WBGT and shared city bicycle activity in New York City (NYC) and San Francisco (SF), USA. Generalized Additive Models examined nonlinear relationships between WBGT and bicycle activity while controlling for rider demographics and temporal trends. Next, bootstrapping estimated the "peak point", when the relationship between the bike rentals and WBGT notably changed.The analysis also examined whether the heat warning messages affected cycling activities. We found that the number of rented bikes declined at different peak points in each city. The peak point was in NYC at 34.3°C (95% CI 33°C-35°C) and 10.8°C (95% CI 10-12°C) in SF. Somewhat paradoxically, bike rentals increased when heat warnings were issued in both cities.

L-theanine mediates the p38MAPK signaling pathway to alleviate heat-induced oxidative stress and inflammation in mice

L-theanine, an active ingredient in the tea plant (Camellia sinensis) associated with calming, is widely used as a functional ingredient and dietary supplement. In this study, a heat stress mouse...

Exertional heat stroke with reversible severe cerebral edema

Severe cerebral edema associated with exertional heat stroke is a major cause of death or disability. However, few studies on severe cerebral edema resulting from heat stroke have reported neuroradiological findings. Moreover, all the patients in these previous reports either died or remained severely disabled. Here, we report a case of exertional heat stroke with severe cerebral edema that probably developed or worsened due to delayed body temperature normalization. In contrast to previous reports, the patient showed complete clinical and neuroradiological recovery. This rare case suggests that severe cerebral edema could be reversed through meticulous supportive management. Moreover, it confirms the importance of rapid and effective cooling in heat stroke treatment.

Evidence-Based Heatstroke Management in the Emergency Department

Introduction

Climate change is causing an increase in the frequency and intensity of extreme heat events, which disproportionately impact the health of vulnerable populations. Heatstroke, the most serious heat-related illness, is a medical emergency that causes multiorgan failure and death without intervention. Rapid recognition and aggressive early treatment are essential to reduce morbidity and mortality. The objective of this study was to evaluate current standards of care for the emergent management of heatstroke and propose an evidence-based algorithm to expedite care.

Methods

We systematically searched PubMed, Embase, and key journals, and reviewed bibliographies. Original research articles, including case studies, were selected if they specifically addressed the recognition and management of heatstroke in any prehospital, emergency department (ED), or intensive care unit population. Reviewers evaluated study quality and abstracted information regarding demographics, scenario, management, and outcome.

Results

In total, 63 articles met full inclusion criteria after full-text review and were included for analysis. Three key themes identified during the qualitative review process included recognition, rapid cooling, and supportive care. Rapid recognition and expedited external or internal cooling methods coupled with multidisciplinary management were associated with improved outcomes. Delays in care are associated with adverse outcomes. We found no current scalable ED alert process to expedite early goal-directed therapies.

Conclusion

Given the increased risk of exposure to heat waves and the time-sensitivity of the condition, EDs and healthcare systems should adopt processes for rapid recognition and management of heatstroke. This study proposes an evidence-based prehospital and ED heat alert pathway to improve early diagnosis and resource mobilization. We also provide an evidence-based treatment pathway to facilitate efficient patient cooling. It is hoped that this protocol will improve care and help healthcare systems adapt to changing environmental conditions.

The multiple organs insult and compensation mechanism in mice exposed to hypobaric hypoxia

This study was first and systematically conducted to evaluate the hypoxia response of the brain, heart, lung, liver, and kidney of mice exposed to an animal hypobaric chamber. First, we examined the pathological damage of the above tissues by Hematoxylin & eosin (H&E) staining. Secondly, biochemical assays were used to detect oxidative stress indicators such as superoxide dismutase (SOD), malondialdehyde (MDA), reduced glutathione (GSH), and oxidized glutathione (GSSG). Finally, the hypoxia compensation mechanism of tissues was evaluated by expression levels of hypoxia-inducible factor 1 alpha (HIF-1α), erythropoietin (EPO), and vascular endothelial growth factor (VEGF). During the experiment, the mice lost weight gradually on the first 3 days, and then, the weight loss tended to remain stable, and feed consumption showed the inverse trend. H&E staining results showed that there were sparse and atrophic neurons and dissolved chromatin in the hypoxia group. And hyperemia occurred in the myocardium, lung, liver, and kidney. Meanwhile, hypoxia stimulated the enlargement of myocardial space, the infiltration of inflammatory cells in lung tissue, the swelling of epithelial cells in hepatic lobules and renal tubules, and the separation of basal cells. Moreover, hypoxia markedly inhibited the activity of SOD and GSH and exacerbated the levels of MDA and GSSG in the serum and five organs. In addition, hypoxia induced the expression of HIF-1α, EPO, and VEGF in five organs. These results suggest hypoxia leads to oxidative damage and compensation mechanism of the brain, heart, lung, liver, and kidney in varying degrees of mice.

Variation in Clinical Presentations and Outcomes of Heat Stroke Victims in the Mass-Casualty Setting

BACKGROUND

Immigrants crossing the Southern U.S. border are particularly susceptible to heat illness. We review 3 patients from a heat-related mass-casualty incident with variations in heat stroke presentation, course, and outcome.

CASE REPORT

On July 23, 2017, emergency medical services responded to a trafficking-related mass-casualty incident in San Antonio, Texas, involving 39 migrants found inside an abandoned tractor trailer without air conditioning who had been trafficked from Laredo, Texas. Three victims exhibiting heat stroke symptoms were taken to the ED of a large academic teaching hospital. Patient 1 was a 42-year-old man who presented with seizing, vomiting, and a core temperature of 38.8°C (101.8°F). His 54-day hospital course was notable for 2 cardiac arrests, disseminated intravascular coagulation, prolonged lactic acidosis, and residual kidney disease. Patient 2 was a 32-year-old man who presented to the emergency department intubated in the field with a core temperature of 40.7°C (105.3°F). His 60-day hospital course was notable for disseminated intravascular coagulation, severely elevated troponin, prolonged lactic acidosis, and stroke. Patient 3 was a 20-year-old man who presented with seizing and decorticate posturing, with a core temperature of 40.5°C (104.9°F). His 6-day hospital course was notable for rapid clinical improvement and full recovery. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians will encounter heat stroke victims. Our patients were exposed to an identical environment, and while each patient was otherwise healthy and differed significantly only in age, they exhibited a diversity of heat stroke presentations and sequelae. Treatment prioritizes cooling, but rapid deterioration requires intensive treatment of multiorgan failure.

A 3-year retrospective analysis of elderly patients with heat illness

Background:

Heat illness in elderly patients has frequently occurred. Because of the difficulties in diagnosis and treatment, it is necessary for us to understand the clinical characteristics of elderly patients with heat illness.

Objective:

This study presents the demographic, clinical, and laboratory data for elderly patients who presented to our emergency department with heat illness and compares elderly group and non-elderly group to find out characteristics of elderly patient.

Methods:

We retrospectively analyzed the data of the elderly heat illness patients who had been presented to the emergency department of Jinshan Hospital, Fudan University, between 1 July 2014 and 1 October 2016.

Results:

There were 64 patients in the study in total and 25 elderly patients (39.1%). The mean age of the elderly patients was 72.8 ± 6.7 years; 18 cases (72%) were male and 7 cases (28%) were female. There were 5 mild cases (20%) and 20 severe cases (80%) in the elderly, which included 1 with heat cramps (5%), 4 with heat exhaustion (20%), and 15 with heat stroke (75%). Lactate dehydrogenase and creatine kinase were significantly higher in the elderly than in the non-elderly (p < 0.0001; t-value = −3.915 and −5.134, respectively). The Acute Physiologic Assessment and Chronic Health Evaluation II score and Modified Early Warning System score were significantly higher in the elderly than in the non-elderly (p < 0.0001; t-value = −6.411 and −4.705, respectively). Age was positively correlated with the Acute Physiologic Assessment and Chronic Health Evaluation II score and Modified Early Warning System score (r2 = 0.4939 and 0.3317, respectively; p value all <0.0001). The Acute Physiologic Assessment and Chronic Health Evaluation II score was positively correlated with lactate dehydrogenase and creatine kinase (r2 = 0.4103 and 0.4520, respectively; p value all <0.0001). The Modified Early Warning System score was positively correlated with lactate dehydrogenase and creatine kinase (r2 = 0.4759 and 0.5850, respectively; p value all <0.0001). There were 19 patients (76%) who improved and 6 patients (24%) who died in the elderly group.

Conclusion:

Chronic diseases and complications have increased rates in the elderly, who are also more likely to acquire severe heat illness, especially heat stroke. Lactate dehydrogenase and creatine kinase are positively correlated with Acute Physiologic Assessment and Chronic Health Evaluation II scores and Modified Early Warning System scores, which indicates that lactate dehydrogenase and creatine kinase could be good predictors of the severity of heat illness.

Timing and Predictors of Mild and Severe Heat Illness among New Military Enlistees

PURPOSE

Heat illnesses are important and potentially fatal conditions among physically active individuals. We determined predictors of heat illness among enlistees in a large military population experiencing common physical activity patterns.

METHODS

We estimated the adjusted odds of mild (MHI) and severe (SHI) heat illness associated with demographic, health-related, and geographic factors among active-duty, US Army soldiers enlisting between January 2011 and December 2014 (N = 238,168) using discrete-time multivariable logistic regression analyses.

RESULTS

We observed 2612 incident cases of MHI and 732 incident cases of SHI during 427,922 person-years of follow-up, with a mean and median of 21.6 and 21 months per subject. During the first 6 duty months, 71.3% of the MHIs and 60.2% of the SHIs occurred, peaking at month 2. The odds of MHI quadrupled among those with prior SHI (odds ratio [OR], 4.02; 95% confidence interval [CI], 2.67-6.03). Body mass index (BMI) extremes increased the odds substantially (OR at BMI ≥30 kg·m: for MHI, 1.41 (CI, 1.19-1.67); for SHI, 1.94 (CI, 1.47-2.56); OR at BMI <18.5 kg·m: for MHI, 1.50 (CI, 1.01-2.21); for SHI, 2.26 (CI, 1.16-4.39)). Tobacco use was associated with a 55% increase (CI, 1.37-1.77) in MHI odds. The odds of MHI increased if taking nonsteroidal anti-inflammatory drugs, opioids, or methylphenidate stimulants. Lower age and lower entry aptitude scores were associated with progressively increased MHI odds.

CONCLUSIONS

Most heat illnesses occurred at the outset of service, indicating the need for focused prevention methods at the initiation of military duty. Prior heat illness, BMI extremes, medications, and tobacco use represent potentially actionable risk factors to address by education, policy, and/or clinician intervention.

Practical pre-cooling methods for occupational heat exposure

This study aimed to identify a pre-cooling method to reduce the physiological and perceptual strain, and the inflammatory response, experienced by individuals who wear personal protective equipment. Eleven males (age 20 ± 2 years, weight 75.8 ± 9.3 kg, height 177.1 ± 5.0 cm) completed 15min pre-cooling (phase change vest [PCV], forearm cooling [ARM], ice slurry consumption [ICE], or a no cooling control [CON]) and 45min intermittent walk (4  km h^-1, 1% gradient) in 49.5 ± 0.6 °C and 15.4 ± 1.0% RH, whilst wearing firefighter ensemble. ICE reduced rectal temperature (T_re) before heat exposure compared to CON (ΔT_re: 0.24 ± 0.09 °C, p < 0.001, d = 0.38) and during exercise compared to CON, ARM, and PCV (p = 0.026, η_p² = 0.145). Thermal sensation was reduced in ICE and ARM vs. CON (p = 0.018, η_p² = 0.150). Interleukin-6 was not affected by pre-cooling (p = 0.648, η_p² = 0.032). It is recommended that those wearing protective equipment consume 500 ml of ice slurry 15min prior to work to reduce physiological and perceptual strain.

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.

Thermal dysregulation in Prader-Willi syndrome: a potentially fatal complication in adolescence, not just in infancy

A 13-year-old boy with a background of Prader-Willi syndrome (PWS) was admitted to the regional paediatric intensive care unit, with community-acquired pneumonia. Despite a week of intravenous antibiotics, resolution of inflammatory markers and resolving consolidation on radiograph, he remained feverish. Fever of unknown origin investigations were negative and he was diagnosed with central thermal dysregulation secondary to hypothalamic dysfunction in PWS. Following a hyperpyrexia period, secondary rhabdomyolysis and renal failure developed. This was successfully managed with active cooling, ventilation and haemofiltration. After weaning from haemofiltration, the patient was successfully extubated to non-invasive respiratory support.

Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged Exercise

PURPOSE

This work examines whether sodium supplementation is important in prevention of hyponatremia during continuous exercise up to 30 h and whether any distinguishing characteristics of those developing hyponatremia could be identified.

METHODS

Participants of the 161-km Western States Endurance Run underwent body weight measurements before, during, and after the race, completed a postrace questionnaire about drinking strategies and use of sodium supplementation during four race segments, and underwent analysis of postrace serum sodium concentration.

RESULTS

The postrace questionnaire was completed by 74.5% of the 376 starters, a postrace blood sample was provided by 61.1% of the 296 finishers, and 53.0% of finishers completed the postrace survey and also provided a postrace blood sample. Among this population, the incidence of hyponatremia among finishers was 6.6% and sodium supplements were used by 93.9% of the runners. Postrace serum sodium concentration was found to be directly related to the rate of sodium intake in supplements (r = 0.24, P = 0.0027) and indirectly related to the percentage change in body weight from immediately before the race start (r = -0.19, P = 0.010). There was no difference in rate of sodium intake in supplements between the hyponatremic and normonatremic finishers, and none of the hyponatremic finishers lost >4.3% body weight. Hyponatremic finishers were not distinguished from normonatremic or hypernatremic finishers by other runner characteristics considered, drinking strategies, or gastrointestinal symptoms of nausea and vomiting.

CONCLUSIONS

We conclude that a low sodium intake in supplements has minimal responsibility for development of hyponatremia during continuous exercise up to 30 h, whereas overhydration is the primary characteristic of those developing hyponatremia. Therefore, avoiding overhydration seems to be the most important means for preventing hyponatremia under these conditions.

Mandatory Rest Stops Improve Athlete Safety during Event Medical Coverage for Ultramarathons

INTRODUCTION

Provisions of medical direction and clinical services for ultramarathons require specific attention to heat illness. Heat stress can affect athlete performance negatively, and heat accumulation without acclimatization is associated with the development of exertional heat stroke (EHS). In order to potentially mitigate the risk of this safety concern, the Jungle Marathon (Para, Brazil) instituted mandatory rest periods during the first two days of this 7-day, staged, Brazilian ultramarathon.

METHODS

Race records were reviewed retrospectively to determine the number of runners that suffered an emergency medical complication related to heat stress and did not finish (DNF) the race. Review of records included three years before and three years after the institution of these mandatory rest periods.

RESULTS

A total of 326 runners competed in the Jungle Marathon during the 2008-2013 period of study. During the pre-intervention years, a total of 46 athletes (21%) DNF the full race with 25 (54.3%) cases attributed to heat-related factors. During the post-intervention years, a total of 26 athletes (24.3%) DNF the full race with four (15.4%) cases attributed to heat-related factors.

CONCLUSION

Mandatory rest stops during extreme running events in hot or tropical environments, like the Jungle Marathon, are likely to improve athlete safety and improve the heat acclimatization process.

Counseling for the Wilderness Athlete and Adventurer During a Preparticipation Evaluation for Preparation, Safety, and Injury Prevention

Wilderness sports and adventures continue to increase in popularity. Counseling is an essential element of the preparticipation evaluation (PPE) for athletes in traditional sports. This approach can be applied to and augmented for the wilderness athlete and adventurer. The authors reviewed the literature on counseling during PPEs and gathered expert opinion from medical professionals who perform such PPEs for wilderness sports enthusiasts. The objective was to present findings of this review and make recommendations on the counseling component of a wilderness sports/adventure PPE. The counseling component of a PPE for wilderness sports/adventures should take place after a basic medical evaluation, and include a discussion on sport or activity-specific injury prevention, personal health, travel recommendations, and emergency event planning. Counseling should be individualized and thorough, and involve shared decision making. This should take place early enough to allow ample time for the athlete or adventurer to further prepare as needed based on the recommendations. Resources may be recommended for individuals desiring more information on selected topics.

Cooling Methods in Heat Stroke

BACKGROUND

Heat stroke is an illness with a high risk of mortality or morbidity, which can occur in the young and fit (exertional heat stroke) as well as the elderly and infirm (nonexertional heat stroke). In the United States, from 2006 to 2010, there were at least 3332 deaths attributed to heat stroke.

OBJECTIVE

To summarize the available evidence on the principal cooling methods used in the treatment of heat stroke.

DISCUSSION

Although it is generally agreed that rapid, effective cooling increases survival in heat stroke, there continues to be debate on the optimal cooling method. Large, controlled clinical trials on heat stroke are lacking. Cooling techniques applied to healthy volunteers in experimental models of heat stroke have not worked as rapidly in actual patients with heat stroke. The best available evidence has come from large case series using ice-water immersion or evaporation plus convection to cool heat-stroke patients.

CONCLUSIONS

Ice-water immersion has been shown to be highly effective in exertional heat stroke, with a zero fatality rate in large case series of younger, fit patients. In older patients with nonexertional heat stroke, studies have more often promoted evaporative plus convective cooling. Evaporative plus convective cooling may be augmented by crushed ice or ice packs applied diffusely to the body. Chilled intravenous fluids may also supplement primary cooling. Based on current evidence, ice packs applied strategically to the neck, axilla, and groin; cooling blankets; and intravascular or external cooling devices are not recommended as primary cooling methods in heat stroke.

Counseling for the Wilderness Athlete and Adventurer During a Preparticipation Evaluation for Preparation, Safety, and Injury Prevention

Wilderness sports and adventures continue to increase in popularity. Counseling is an essential element of the preparticipation evaluation (PPE) for athletes in traditional sports. This approach can be applied to and augmented for the wilderness athlete and adventurer. The authors reviewed the literature on counseling during PPEs and gathered expert opinion from medical professionals who perform such PPEs for wilderness sports enthusiasts. The objective was to present findings of this review and make recommendations on the counseling component of a wilderness sports/adventure PPE. The counseling component of a PPE for wilderness sports/adventures should take place after a basic medical evaluation, and include a discussion on sport or activity-specific injury prevention, personal health, travel recommendations, and emergency event planning. Counseling should be individualized and thorough, and involve shared decision making. This should take place early enough to allow ample time for the athlete or adventurer to further prepare as needed based on the recommendations. Resources may be recommended for individuals desiring more information on selected topics.

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.

Wilderness Medical Society practice guidelines for the prevention and treatment of heat-related illness: 2014 update

The Wilderness Medical Society (WMS) convened an expert panel to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. We present a review of the classifications, pathophysiology, and evidence-based guidelines for planning and preventive measures as well as best practice recommendations for both field and hospital-based therapeutic management of heat illness. These recommendations are graded on the basis of the quality of supporting evidence, and balance between the benefits and risks or burdens for each modality. This is an updated version of the original WMS Practice Guidelines for the Prevention and Treatment of Heat-Related Illness published in Wilderness & Environmental Medicine 2013;24(4):351-361.

Managing collapsed or seriously ill participants of ultra-endurance events in remote environments

Increasing participation in ultramarathons and other ultra-endurance events amplifies the potential for serious medical issues during and immediately following these competitions. Since these events are often located in remote settings where access may be extremely limited; the diagnostic capabilities, treatment options, and expectations of medical care may differ from those of urban events. This work outlines a process for assessment and treatment of athletes presenting for medical attention in remote environments, with a focus on potentially serious conditions such as major trauma, acute coronary syndrome, exertional heat stroke, hypothermia, hypoglycemia, exercise-associated hyponatremic encephalopathy, severe dehydration, altitude illness, envenomation, anaphylaxis, and bronchospasm. A list of suggested medical supplies is provided and discussed. But, given that diagnostic and treatment options may be extremely limited in remote settings, it is important for medical providers to understand how to assess and manage the most common serious medical issues with limited resources, and to be prepared to make presumptive diagnoses when necessary.

Dangers of Prehospital Cooling: A Case Report of Afterdrop in a Patient with Exertional Heat Stroke

BACKGROUND

Exertional heat stroke is a potentially life-threatening disease with varying clinical presentations and severity. Given the severe morbidity that can accompany the disease, the immediate management often begins in the prehospital setting. It is important to have not only a comprehensive understanding of the prehospital cooling methods in addition to hospital management strategies, but an understanding of their potential complications as well.

CASE REPORT

A 32-year-old male presented to a San Antonio hospital in March 2014 with progressive confusion, nausea, nonbloody emesis, and ataxia. Initial presentation was concerning for exertional heat stroke, as the patient was recorded in the field to have a temperature of 42.1°C (106.2°F). The patient, on arrival to the emergency department, was found to have a core body temperature of 38.1°C (100.6°F). All active cooling measures were terminated and active rewarming was initiated. Despite adequate resuscitation and rapid identification of the patient's overcorrection in core body temperature, the lowest recorded temperature was 36.0°C (96.8°F). Why Should an Emergency Physician Be Aware of This? This case represents the dangers associated with exertional heat stroke, overcorrection of core body temperature, and the potentially lethal complication of afterdrop. It also represents the need for immediate recognition of the condition and initiation of appropriate medical care. Although this patient's clinical outcome was good, the event could have caused serious morbidity or could have potentially been fatal.

Exertional Heat Illness: Emerging Concepts and Advances in Prehospital Care

Exertional heat illness is a classification of disease with clinical presentations that are not always diagnosed easily. Exertional heat stroke is a significant cause of death in competitive sports, and the increasing popularity of marathons races and ultra-endurance competitions will make treating many heat illnesses more common for Emergency Medical Services (EMS) providers. Although evidence is available primarily from case series and healthy volunteer studies, the consensus for treating exertional heat illness, coupled with altered mental status, is whole body rapid cooling. Cold or ice water immersion remains the most effective treatment to achieve this goal. External thermometry is unreliable in the context of heat stress and direct internal temperature measurement by rectal or esophageal probes must be used when diagnosing heat illness and during cooling. With rapid recognition and implementation of effective cooling, most patients suffering from exertional heat stroke will recover quickly and can be discharged home with instructions to rest and to avoid heat stress and exercise for a minimum of 48 hours; although, further research pertaining to return to activity is warranted.

PryorRR,RothRN,SuyamaJ,HostlerD.Exertional heat illness: emerging concepts and advances in prehospital care.Prehosp Disaster Med.2015;30(3):19.

Clearance of serum solutes by hemofiltration in dogs with severe heat stroke

Background

We have previously reported that hemofiltration (HF) may be an effective additional means of treating heat stroke when rapid cooling is not effective.

Methods

Dogs were assigned to a heat stroke (control) or heat stroke + hemofiltration (HF) group (n = 8 each group). After heat stroke induction, dogs in the HF group received HF for 3 h. Serum concentrations of interleukin (IL)-10, tumor necrosis factor (TNF)-α, IL-6, blood urea nitrogen (BUN) and creatinine were measured at baseline and 1, 2, and 3 h after heat stroke. Clearance rates of solutes were determined 1, 2, and 3 h after the start of HF.

Results

Serum concentrations of all solutes tended to increase with time after heat stroke in the control group, but decreased (BUN, creatinine) or remained relatively unchanged (TNF-α, IL-6, IL-10) with time in the HF group. Concentrations of all solutes were significantly lower in the HF group compared with the control group at 2 and 3 h (P < 0.05). Clearance rates for small molecular weight solutes were high, while those for larger molecular weight solutes were low.

Conclusion

HF prevents heat stroke-induced increases in serum cytokine concentrations and is effective for clearing small molecular weight solutes from serum, but less effective for clearing larger molecular weight solutes, including TNF-α, IL-6, and IL-10.

Evaluation and treatment of injury and illness in the ultramarathon athlete

Participation in ultramarathon races and knowledge of these athletes continues to increase as the sport becomes more popular. Physicians and athletes need to better understand the impact of the unique aspects of ultramarathon races, such as race environment (temperature, humidity, and altitude), race distance, race stages, nutritional requirements and equipment, on athlete injuries and illness. Proper treatment of injuries and illnesses during an ultramarathon race is important for avoiding long-term medical issues. In this article, the evaluation and treatment of common musculoskeletal injuries and medical illnesses in ultramarathon runners are reviewed.

Wilderness medicine

BACKGROUND

Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.

METHODS

The field of wilderness medicine encompasses many areas of interest. Some focus on special circumstances (such as avalanches) while others have a broader scope (such as trauma care). Several core areas of key interest within wilderness medicine are discussed in this study.

RESULTS

Wilderness medicine is characterized by remote and improvised care of patients with routine or exotic illnesses or trauma, limited resources and manpower, and delayed evacuation to definitive care. Wilderness medicine is developing rapidly and draws from the breadth of medical and surgical subspecialties as well as the technical fields of mountaineering, climbing, and diving. Research, epidemiology, and evidence-based guidelines are evolving. A hallmark of this field is injury prevention and risk mitigation. The range of topics encompasses high-altitude cerebral edema, decompression sickness, snake envenomation, lightning injury, extremity trauma, and gastroenteritis. Several professional societies, academic fellowships, and training organizations offer education and resources for laypeople and health care professionals.

CONCLUSIONS

THE FUTURE OF WILDERNESS MEDICINE IS UNFOLDING ON MULTIPLE FRONTS: education, research, training, technology, communications, and environment. Although wilderness medicine research is technically difficult to perform, it is essential to deepening our understanding of the contribution of specific techniques in achieving improvements in clinical outcomes.