Wilderness Medical Society Practice Guidelines for Treatment of Exercise-Associated Hyponatremia

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.

Four Cases of Acute Kidney Injury Requiring Dialysis in Ultramarathoners

Transient acute kidney injury (AKI) following ultraendurance footraces is a common biochemical diagnosis. However, severe AKI requiring renal replacement therapy is uncommon in ultramarathoners. We report 4 runners (3 men; mean age, 44 ± 3 y) who required prolonged (10-42 d) dialysis following the Western States 100 Mile Endurance Run over a 3-y span (0.38% of starters). The maximum ambient temperatures on the race day ranged from 36.6° to 38.3°C. The runners presented to local hospitals 17 to 32 h after running, with laboratories confirming rhabdomyolysis, hyponatremia (mean serum sodium concentration, 127±2 mmol⋅L-1), and AKI (mean serum creatinine concentration, 8.5±2 mg⋅dL-1). The case-cluster report highlights the potential synergistic effects of high ambient temperatures, muscle damage, and electrolyte imbalance on protracted renal dysfunction in ultramarathoners competing in a warming world.

Hydration Strategies for Physical Activity and Endurance Events at High (>2500 m) Altitude: A Practical Management Article

A growing number of adventurous athletes are seeking new challenges through endurance events or physical activities held at high altitude (>2500 m). This coincides with a significant increase in the numbers of trekkers who ascend into the world's mountains. Altitude itself influences and complicates the athlete's effective and safe hydration. This article considers the physiology of adaptation to altitude and the effects on hydration at altitude compared with sea level, reviews the "ad libitum versus programmed hydration" controversy in conventional endurance event hydration, examines the evidence for extrapolation of sea level hydration strategies to the high-altitude environment, and synthesizes these disparate factors into a set of practical recommendations for hydration management during high-altitude physical activity. The guidelines will be relevant to participants of physical activity at altitude and health care staff who may care for them in the preparation or performance phases of their adventure.

[Medical emergencies during running events]

Hintergrund

Die Anzahl an kurz- und langstreckigen Laufveranstaltungen in Deutschland nimmt zu. Laufen als Breitensport wird von einer Vielzahl an Personen unterschiedlicher Altersklassen, Risikogruppen und Professionalisierungsgrade betrieben, woraus ein breites Spektrum medizinischer Notfälle resultiert.

Ziel der Arbeit

Der vorliegende Beitrag erläutert die Inzidenz, Pathophysiologie und Therapie relevanter Notfallbilder bei Laufveranstaltungen. Ziel ist die Optimierung der Arbeitsabläufe des Rettungsdienstpersonals.

Material und Methoden

Es erfolgte eine Literaturrecherche in PubMed.

Ergebnisse

Anstrengungsassoziierte Muskelkrämpfe, gastrointestinale Symptome, Kollaps, Kompartmentsyndrom und Tendinopathien sind häufige Erscheinungsbilder und resultieren meist aus akuter oder chronischer Überanstrengung. Der Kreislaufstillstand bzw. plötzliche Herztod ist ein seltenes Ereignis bei Laufveranstaltungen. Bewusstseinsstörungen und generalisierte Krampfanfälle sind schwerwiegende Komplikationen. Disseminierte intravasale Koagulopathie, belastungsinduzierte Hyponatriämie, Hitzschlag, Rhabdomyolyse und thromboembolische Ereignisse sind mit hoher Morbidität und Mortalität verbunden. Substanzen zur Erhöhung der Schmerzschwelle und leistungssteigernde Substanzen sind unter Läufern stark verbreitet und gehen mit einer hohen Rate an Nebenwirkungen einher.

Diskussion

Unspezifische Symptome wie Erbrechen, Fieber, Kollaps, Muskelschmerzen, Übelkeit, und Schwäche sind die führenden Symptome bei Laufveranstaltungen. Eine sorgfältige Anamnese ist wegweisend für eine zielgerichtete klinische Therapie. Präklinisch steht eine Symptomkontrolle im Mittelpunkt. Das Flüssigkeitsmanagement stellt eine besondere Herausforderung dar.

Treatment of symptomatic hyponatremia with hypertonic saline: a real-life observational study

OBJECTIVE

Treatment of symptomatic hyponatremia is not well established. The European guidelines recommend bolus-wise administration of 150 mL of 3% hypertonic saline. This recommendation is, however, based on low level of evidence.

DESIGN

Observational study.

METHODS

Sixty-two consecutive hyponatremic patients admitted to the emergency department or intensive care unit of the University Hospital Wuerzburg were divided in subgroups according to treatment (150 mL bolus of 3% hypertonic saline or conventional treatment) and symptom severity. Treatment target was defined as an increase in serum sodium by 5-10 mEq/L within first 24 h and maximum 8 mEq/L during subsequent 24 h.

RESULTS

Thirty-three out of sixty-two patients (53%) were presented with moderate symptoms and 29/62 (47%) with severe symptoms. Thirty-six were treated with hypertonic saline and 26 conventionally. In the hypertonic saline group, serum sodium increased from 116 ± 7 to 123 ± 6 (24 h) and 127 ± 6 mEq/L (48 h) and from 121 ± 6 to 126 ± 5 and 129 ± 4 mEq/L in the conventional group, respectively. Overcorrection at 24 h occurred more frequent in patients with severe symptoms than with moderate symptoms (38% vs 6%, P < 0.05). Diuresis correlated positively with the degree of sodium overcorrection at 24 h (r = 0.6, P < 0.01). Conventional therapies exposed patients to higher degrees of sodium fluctuations and an increased risk for insufficient sodium correction at 24 h compared to hypertonic saline (RR: 2.8, 95% CI: 1.4-5.5).

CONCLUSION

Sodium increase was more constant with hypertonic saline, but overcorrection rate was high, especially in severely symptomatic patients. Reducing bolus-volume and reevaluation before repeating bolus infusion might prevent overcorrection. Symptoms caused by hypovolemia can be misinterpreted as severely symptomatic hyponatremia and diuresis should be monitored.

Collapse in the Heat - From Overhydration to the Emergency Room - Three Cases of Exercise-Associated Hyponatremia Associated with Exertional Heat Illness

Exertional heat illness and exercise-associated hyponatremia continue to be a problem in military and recreational events. Symptoms of hyponatremia can be mistaken for heat exhaustion or heat stroke. We describe three cases of symptomatic hyponatremia initially contributed to heat illnesses. The first soldier was a 31-yr-old female who "took a knee" at mile 6 of a 12-mile foot march. She had a core temperature of 100.9°F, a serum sodium level of 129 mmol/L, and drank approximately 4.5 quarts of water in 2 h. The second case was a 27-yr-old female soldier who collapsed at mile 11 of a 12-mile march. Her core temperature was 102.9°F and sodium level was 131 mmol/L. She drank 5 quarts in 2.5 h. The third soldier was a 27-yr-old male who developed nausea and vomiting while conducting an outdoor training event. His core temperature was 98.7°F and sodium level was 125 mmol/L. He drank 6 quarts in 2 h to combat symptoms of heat. All the three cases developed symptomatic hyponatremia by overconsumption of fluids during events lasting less than 3 h. Obtaining point-of-care serum sodium may improve recognition of hyponatremia and guide management for the patient with suspected heat illness and hyponatremia. Depending on severity of symptoms, exercise-associated hyponatremia can be managed by fluid restriction, oral hypertonic broth, or with intravenous 3% saline. Utilizing an ad libitum approach or limiting fluid availability during field or recreational events of up to 3 h may prevent symptomatic hyponatremia while limiting significant dehydration.

Top 10 Research Questions Related to Preventing Sudden Death in Sport and Physical Activity

Participation in organized sport and recreational activities presents an innate risk for serious morbidity and mortality. Although death during sport or physical activity has many causes, advancements in sports medicine and evidence-based standards of care have allowed clinicians to prevent, recognize, and treat potentially fatal injuries more effectively. With the continual progress of research and technology, current standards of care are evolving to enhance patient outcomes. In this article, we provided 10 key questions related to the leading causes and treatment of sudden death in sport and physical activity, where future research will support safer participation for athletes and recreational enthusiasts. The current evidence indicates that most deaths can be avoided when proper strategies are in place to prevent occurrence or provide optimal care.

Nutritional implications for ultra-endurance walking and running events

This paper examines the various nutritional challenges which athletes encounter in preparing for and participating in ultra-endurance walking and running events. Special attention is paid to energy level, performance, and recovery within the context of athletes' intake of carbohydrate, protein, fat, and various vitamins and minerals. It outlines, by way of a review of literature, those factors which promote optimal performance for the ultra-endurance athlete and provides recommendations from multiple researchers concerned with the nutrition and performance of ultra-endurance athletes. Despite the availability of some research about the subject, there is a paucity of longitudinal material which examines athletes by nature and type of ultra-endurance event, gender, age, race, and unique physiological characteristics. Optimal nutrition results in a decreased risk of energy depletion, better performance, and quicker full-recovery.

The influence of hydration state on thermoregulation during a 161-km ultramarathon

It is advised that individuals should avoid losing >2% of their body mass during exercise in order to prevent hyperthermia. This study sought to assess whether a loss of >2% body mass leads to elevations in core temperature during an ultramarathon. Thirty runners agreed to take part in the study. Body mass and core temperature were measured at the start, at three locations during the race and the finish. Core temperature was not correlated with percent body mass change (p = 0.19) or finish time (p = 0.11). Percent body mass change was directly associated with finish time (r = 0.58, p < 0.01), such that the fastest runners lost the most mass (~3.5-4.0%). It appears that a loss of >3% body mass does not contribute to rises in core temperature. An emphasis on fluid replacement for body mass losses of this magnitude during prolonged exercise is not justified as a preventative measure for heat-related illnesses.

High incidence of hyponatremia in rowers during a four-week training camp

PURPOSE

To investigate the incidence of hyponatremia and its relationship to plasma copeptin, a surrogate marker for arginine vasopressin (AVP) during 28 days of high-volume rowing training.

METHODS

Thirty rowers from the German junior national team (21 male) were studied during a training camp. Serum sodium ([Na(+)]), osmolality, and copeptin were measured before the beginning of the camp (day 0), and at days 7, 13, 18, 24, and 28. Daily fluid intake, body weight, urine parameters, and training volume were recorded.

RESULTS

Seventy percent of the rowers developed hyponatremia at least once. At day 18, training volume and incidence of hyponatremia (43%) were highest. [Na(+)] decreased from 143 ± 9 mmol·L(-1) (day 0) to 135 ± 5 mmol·L(-1) (day 18, P < .01). Hyponatremia was correlated significantly with weight gain compared with the previous day (P < .01). Copeptin decreased from day 0 to 28 (male: 6.7 ± 2.8 to 3.6 ± 1.7 pmol·L(-1); P < .05; female: 4.8 ± 1.1 to 3.2 ± 1.5 pmol·L(-1); P < .05), being only partially suppressed. Relative fluid intake per body surface area increased from day 7 (male: 2.79 ± 0.78 L·m(-2); female: 2.20 ± 0.70 L·m(-2)) to day 28 (3.88 ± 0.69 L·m(2) and 2.65 ± 0.93 L·m(-2); P < .05). No athlete developed symptomatic hyponatremia.

CONCLUSION

Prolonged high-volume rowing training can lead to a high incidence of hyponatremia. Overdrinking and inadequate suppression of AVP contribute to its development.

Fatal water intoxication and cardiac arrest in runners during marathons: prevention and treatment based on validated clinical paradigms

Cerebral edema due to exercise-associated hyponatremia and cardiac arrest due to atherosclerotic heart disease cause rare marathon-related fatalities in young female and middle-aged male runners, respectively. Studies in asymptomatic middle-aged male physician-runners during races identified inflammation due to skeletal muscle injury after glycogen depletion as the shared underlying cause. Nonosmotic secretion of arginine vasopressin as a neuroendocrine stress response to rhabdomyolysis mediates hyponatremia as a variant of the syndrome of inappropriate antidiuretic hormone secretion. Fatal hyponatremic encephalopathy in young female runners was curtailed using emergent infusion of intravenous hypertonic (3%) saline to reverse cerebral edema on the basis of this paradigm. This treatment was arrived at through a consensus process within the medical community. An increasing frequency of cardiac arrest and sudden death has been identified in middle-aged male runners in 2 studies since the year 2000. Same-aged asymptomatic male physician-runners showed post-race elevations in interleukin-6 and C-reactive protein, biomarkers that predict acute cardiac events in healthy persons. Hypercoagulability with in vivo platelet activation and release of cardiac troponin and N-terminal pro-brain natriuretic peptide were also observed post-race in these same subjects. High short-term risk for atherothrombosis during races as shown by stratification of biomarkers in asymptomatic men may render nonobstructive coronary atherosclerotic plaques vulnerable to rupture. Pre-race aspirin use in this high-risk subgroup is prudent according to conclusive evidence for preventing first acute myocardial infarctions in same-aged healthy male physicians. On the basis of validated clinical paradigms, taking a low-dose aspirin before a marathon and drinking to thirst during the race may avert preventable deaths in susceptible runners.

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.

Three cases of severe hyponatremia during a river run in Grand Canyon National Park

We present 3 cases of severe hyponatremia occurring on a commercially guided river rafting trip on the Colorado River in Grand Canyon National Park. All 3 women appeared to have been overhydrating because of concern about dehydration and required evacuation within 24 hours of each other after the staggered onset of symptoms, which included fatigue and emesis progressing to disorientation or seizure. Each was initially transferred to the nearest hospital and ultimately required intensive care. Imaging and laboratory data indicated all 3 patients had hypervolemic hyponatremia. Unlike the well-documented exercise-associated hyponatremia cases commonly occurring in prolonged endurance athletic events, these 3 unique cases of acute hyponatremia were not associated with significant exercise. The cases illustrate the diagnostic and treatment challenges related to acute hyponatremia in an austere setting, and underscore the importance of preventive measures focused on avoidance of overhydration out of concern for dehydration.

Physiopathological, Epidemiological, Clinical and Therapeutic Aspects of Exercise-Associated Hyponatremia

Exercise-associated hyponatremia (EAH) is dilutional hyponatremia, a variant of inappropriate antidiuretic hormone secretion (SIADH), characterized by a plasma concentration of sodium lower than 135 mEq/L. The prevalence of EAH is common in endurance (<6 hours) and ultra-endurance events (>6 hours in duration), in which both athletes and medical providers need to be aware of risk factors, symptom presentation, and management. The development of EAH is a combination of excessive water intake, inadequate suppression of the secretion of the antidiuretic hormone (ADH) (due to non osmotic stimuli), long race duration, and very high or very low ambient temperatures. Additional risk factors include female gender, slower race times, and use of nonsteroidal anti-inflammatory drugs. Signs and symptoms of EAH include nausea, vomiting, confusion, headache and seizures; it may result in severe clinical conditions associated with pulmonary and cerebral edema, respiratory failure and death. A rapid diagnosis and appropriate treatment with a hypertonic saline solution is essential in the severe form to ensure a positive outcome.

Exercise-associated hyponatremic encephalopathy in an endurance open water swimmer

Exercise-associated hyponatremia and its more serious form, known as exercise-associated hyponatremic encephalopathy, are recognized as some of the most important medical problems seen in a variety of different forms of endurance exercise. We describe a case of exercise-associated hyponatremic encephalopathy presenting as altered conscious state and seizures in a woman who had completed a 20-km open ocean swim. Her serum sodium measured approximately 1 hour after her seizure was 119 mmol/L on point-of-care testing. With ongoing critical care support and the use of hypertonic saline, she was able to be extubated the next day, neurologically intact, and ultimately was discharged from hospital without neurological sequelae. This case emphasizes both the importance of considering exercise-associated hyponatremic encephalopathy as a cause of neurological impairment in all athletes and the pivotal role of hypertonic saline in the treatment of this condition.

Characterization of medical care at the 161-km Western States Endurance Run

OBJECTIVE

To examine the medical care at a highly competitive 161-km mountain ultramarathon.

METHODS

Encounter forms from the 2010 through 2013 Western States Endurance Run were analyzed for trends in consultation and use of intravenous fluids.

RESULTS

A total of 63 consultations (8.2% of starters) were documented in 2012 and 2013, of which 10% involved noncompetitors. Most (77%) of the consultations with competitors occurred on the course rather than at the finish line, and were generally during the middle third of the race. Of the on-course consultations, the runner was able to continue the race 55% of the time, and 75% of those who continued after consultation ultimately finished the race. Relative number of consultations did not differ among competitors within 10-year age groups (P = .7) or between men and women (P = .2). Overall, consultations for medical issues were predominant, and nausea and vomiting accounted for the single highest reason for consultation (24%). Although there was an overall decrease in finish line consultations and intravenous fluid use from 2010 through 2013 (P < .0001 for both) that was independent of maximum ambient temperature (P = .3 and P = .4), the proportion of those being treated with intravenous fluids relative to those receiving consultation at the finish line was directly related to maximum ambient temperature (r = .93, P = .037). Both 2012 and 2013 had a single medical emergency that required emergency evacuation.

CONCLUSIONS

This work demonstrates that the medical needs in a 161-km ultramarathon are mostly for minor issues. However, occasional serious issues arise that warrant a well-organized medical system.

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.