of Exertional Heat Stroke in Athletics: Interdisciplinary Medical Care


Fig. 9.1

Basic paradigm for the care of exertional heat stroke. (From Belval et al. [9], with permission)



Medical professionals in athletic settings are faced with unique challenges for managing EHS. For example, the need for early recognition and assessment of EHS warrant qualified medical personnel (e.g., athletic trainer) to be on-site at athletic fields, which may not be feasible in some settings. Optimal EHS triage also asks to prioritize on-site treatment (i.e., aggressive, whole-body cooling) over transportation to an advanced medical facility, which may not be intuitive for many medical professionals, considering that most injuries are treated after the patient has been transported to the hospital [9]. Thus, successful management of EHS in athletics requires a well-established network of nonmedical and medical personnel to seamlessly deliver best practice in prevention, pre-hospital care, transport, and in-hospital care. This chapter will summarize key aspects of optimal EHS management while identifying key individuals (e.g., administrators, coaches, parents, athletic trainers, emergency medical service [EMS], physicians) who are responsible for carrying out the tasks needed to build an interdisciplinary network to successfully treat an athlete with EHS. In addition to local (i.e., team based) efforts, policy-based interventions can influence society at large and may be a useful method to establish a consensus across differing level of societal influence (e.g., team, school, region, state, league, nation) [10]. Policies introduced in the last decade pertaining to optimal prevention and treatment of EHS have shown favorable results to suggest that policy-based effort can promote both global and local changes. These successes in systematically overhauling the EHS management through policy-based interventions will also be discussed in the chapter.


Chain of Exertional Heat Stroke Prevention and Survival


Prevention


The first step in EHS management is prevention. Prevention strategies can be classified into those that can help, first, to identify and, second, to reduce risks. For example, preseason screening such as what occurs during an athlete’s pre-participation examination and daily wellness logs can identify intrinsic risk factors that are associated with EHS, such as a history of exertional heat illness, poor fitness level, lack of heat acclimatization, dehydration, recent illness, level of fatigue, and sleep deprivation [2]. Athletes and parents (if the athletes are minors) have the responsibility to report accurate information about their health status so that appropriate risk mitigation plans can be implemented. Such plans include selecting exercise that matches one’s physical fitness, implementing a team-wide heat acclimatization program, providing unlimited access to water to maintain proper hydration, and promoting adequate recovery before sport participation [1, 11]. When risk factors are known, qualified on-site medical personnel (e.g., athletic trainer, physiotherapist) and coaches also have the duties to share the information among each other so that informed decisions can be made when programming exercise mode, duration and intensity. It has been suggested that the presence of multiple risk factors heightens the risk of EHS [12]. Therefore, addressing as many modifiable risk factors identified in the preseason screening and daily wellness logs can be considered as the first line of defense in EHS prevention. A summary of existing literature about risk factors of EHS is further discussed in Chap. 3.


Environmental monitoring can also help identify EHS risk, where studies have shown increased prevalence of EHS fatalities when the environmental conditions are uncharacteristically hot for that specific region [13, 14]. These data support the use of injury surveillance and daily environmental monitoring as tools to determine high risk days for EHS, which can be led by coaches and athletic trainers. They should also determine the level of physical activity according to the wet-bulb globe temperature (WBGT) , an index used to quantify the amount of environmental heat stress by incorporating the influence from solar radiation, air temperature, humidity, and wind speed [11, 14]. It is also important for administrators to reinforce WBGT-based activity modification guidelines to support decisions for shortening or cancelling of physical activity during extreme heat as these decisions can become hard for coaches in the face of competitive athleticism.


Methods that can directly reduce the risk of EHS include heat acclimatization and body cooling [2, 1518]. Qualified on-site medical personnel should exercise due diligence to educate the benefits and importance of these methods to coaches and administrators to receive organizational support. In order to purposefully induce heat acclimatization, a heat acclimatization program must be incorporated within the training periodization to ensure that adequate amount of stress is applied to induce physiological adaptations. In the United States, an Inter-Association Task Force released a set of evidence-based guidelines regarding heat acclimatization in 2009, with the aim to reduce exertional heat illness risk during the summer months, particularly in the American football [19]. Since its introduction, eight states have mandated the implementation of preseason heat acclimatization in secondary school American football, which resulted in a 55% reduction in exertional heat illness (95% confidence interval: 13, 77%) [18]. Heat acclimatization process generally takes 10–14 days [17] and is recommended to be conducted during preseason (i.e., early spring or summer) to allow for gradual progression in physical and thermal loads placed on the body [20]. Heat acclimatization is also a useful method to prepare athletes who have scheduled competitions in regions where the weather conditions are warmer than their home. This not only helps reduce the risk of EHS but also optimizes athletic performance in heat [21].


Pre- (i.e., before activity) and per-cooling (i.e., during activity) are other useful methods to reduce the risk of EHS by directly lowering one’s baseline internal body temperature prior to activity or by attenuating the rise in body temperature during activity, respectively [2, 15]. Since practical cooling strategies vary by setting and sport (i.e., American football is equipment laden but has unlimited number of substitutions, while soccer has a no re-entry rule for substitutions, limiting the opportunity for cooling during pregame and during halftime) [16], it is necessary for coaches and medical personnel to evaluate cooling methods that can be implemented readily. Lastly, it is important to educate coaches about the ergogenic benefits of heat acclimatization for enhancing cardiovascular fitness [17] and body cooling for endurance performance [21]. Coaches should realize that performance optimization in the heat can simultaneously facilitate EHS prevention and performance enhancement.


Pre-hospital Care


When EHS occurs, despite aforementioned prevention efforts, rapid recognition, rapid assessment, and rapid cooling must be carried out to avoid poor prognosis (see Fig. 9.1). Ideally, the pre-hospital care of EHS patients in athletics settings should be led by qualified medical personnel, such as an athletic trainer, as they are trained to recognize early signs and symptoms of EHS, use rectal thermometry to obtain an accurate internal body temperature, and administer cold water immersion to rapidly cool the body below 39 °C while continuously monitoring the internal body temperature [1]. When these steps are followed within the first 30 minutes of collapse, prognosis from EHS is promising [9]. Proper recognition and length of whole-body cooling rely on an accurate temperature assessment using rectal thermometry. However, Mazerolle et al. [22] found lack of rectal thermometry usage by college and high school athletic trainers due to insecurities, organizational barriers, and lack of resources. In such cases, clinicians and administrators should realize the legal implications for not using rectal thermometry since other methods of body temperature assessment (e.g., temporal, tympanic, oral, axillary, skin temperature) have been shown to be invalid for measuring the internal body temperature in individuals during or immediately after exercise [23, 24]. Therefore, both sports medicine and administrative staff members of an athletic team need to understand the essential use of rectal thermometry to accurately diagnose EHS and properly identify the duration of treatment. Information pertaining to the pre-hospital care of EHS patients should be documented in the form of a policies and procedures manual for the sports medicine team and a site-specific emergency action plan (EAP) to effectively carry out these procedures. Policies and procedures will help establish the consensus, while the EAP provides step-by-step process to recognize the condition, to initiate the pre-hospital care, and to transfer the patient to advanced medical facility once the hypothermia has been controlled.


In the absence of athletic trainers or other qualified medical personnel, coaches must rely on context-based inference to determine the presence of EHS since they may not be qualified or trained to use rectal thermometry. For that reason, it is imperative to educate coaches about common risk factors and clinical presentation of signs and symptoms of EHS and draft an EAP for nonmedical personnel so that they can initiate appropriate first aid (i.e., body cooling) and communicate clinical presentations to EMS [25].


Transport


Unlike other medical conditions, EHS requires rapid, on-site treatment (i.e., body cooling), prior to transport to higher level medical care. The key doctrine for EHS survival is “cool first, transport second” [8], and it is important to pre-establish a consensus about the need to prioritize on-site treatment over rapid transport among the sports medicine team. Specifically, EMS are accustomed to quickly transporting patients to advanced care. Therefore, it is imperative for them to understand the significance of minimizing the duration of extreme hyperthermia since the extent of thermal stress can directly impact the severity of EHS and patient outcomes [26]. When EMS is the first medical responder on-site (i.e., no athletic trainer on-site), EMS should obtain a rectal temperature and actively cool the patient on-site or en route to the hospital. As it may be technically difficult to administer effective cooling modalities in a moving ambulance, on-site cooling to a safer core temperature (<39 °C) is preferred. At the time of transport, it is also important to document EHS-specific information in addition to the standard medical record information (Table 9.1). This information will become useful when retrospectively assessing the cause of EHS and identifying individualized plan for return to activity.


Table 9.1

List of exertional heat stroke (EHS)-specific information to document on the patient’s medical chart


















































Time of collapse


Environmental conditions


 Wet-bulb globe temperature


 Air temperature


 Relative humidity


 Wind speed


Signs and symptoms of EHS


 Altered mental status


 Aggression


 Lethargy


 Loss of memory


 Profuse sweating


Activity type


Time of rectal temperature measurement


Initial and subsequent log of rectal temperature


Time to start cooling


Cooling method used for treatment


Ability to hydrate


Previous history of EHS


Personal or family history of malignant hyperthermia


Hematuria


Recent illness


In-Hospital Care and Return to Physical Activity


In ideal conditions, patients will be transported to the hospital following on-site cooling. However, patients may arrive to the hospital’s emergency department (ED) by private vehicle or ambulance with little or no attempt at pre-hospital cooling. Rapid recognition, assessment, and cooling remain the priority for the ED staff. Vital signs including rectal temperature, blood pressure, heart rate, and respiratory rate should be assessed. In the acute phase, tachycardia and hyperventilation is usually observed in EHS patients. For those patients that receive pre-hospital cooling, these values may have returned to the normal range [27]. Cold water immersion in an ED may be challenging due to space and equipment (i.e., tubs, large quantities of ice and water) constraints. Other cooling modalities such as rotating ice water- soaked towels [28] or tarp-assisted cooling [29] may be substituted as effective cooling modalities.


Upon arrival to the ED, EHS patients may be dehydrated and exhibit signs of hypotension and hemoconcentration and hypercalcemia and hyperproteinemia [27]. Oral (if tolerated) or IV fluids may be necessary to restore fluid and electrolyte losses in these instances. In EHS patients, it is also not uncommon to observe a hypothermic overshoot following treatment [12]. The chance of a drastic drop in internal body temperature from pre-hospital treatment and patient’s inability to restore normal body temperature (≈36–37 °C) requires direct (e.g., rectal temperature) and continuous monitoring of internal body temperature. It should be noted that hypothermic patients may need rewarming as the ability to regulate body temperature may be altered in some patients. On the contrary, in the event that a patient’s temperature begins to rise, cooling should be re-instituted. In addition, even after the internal body temperature is stabilized, the inflammatory response and blood coagulation may continue [27]. Blood tests such as blood urea nitrogen (BUN), creatinine (Cr), creatine phosphokinase (CPK), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels should be obtained to quantify the level of muscle damage and monitor renal and liver functions, which are commonly affected in EHS patients [26, 27].


A physician may clear the athlete to low-intensity activity only when full recovery of organ function is confirmed via blood work and subjective symptoms (e.g., 7–21 days post EHS incident) [30]. The progression for return to activity should be supervised by trained personnel (e.g., team physician, primary care physician, athletic trainer, etc.), starting from low-intensity exercise in cool environment to gradually transitioning the intensity and environmental condition to mimic a traditional heat acclimatization protocol [30, 31]. Upon receiving the collapsed athlete’s permission, it is ideal for the medical records taken at the time of hospital admittance be shared with qualified medical personnel who will have daily contact with the athlete during the return to activity progression to gauge the extent of initial damage incurred by the body. When the athlete has regained adequate physical fitness and heat tolerance, a standardized heat tolerance test [30, 32] can be prescribed to assess the athlete’s ability to withstand a fixed exercise protocol in heat. Medical lab results, changes in clinical symptoms (e.g., lethargy, weakness), and heat tolerance test results should be evaluated together by the physician and/or athletic trainer, to comprehensively evaluate the athlete’s readiness to return to full activity.


Policy-Based Intervention


Optimization of EHS management requires the sports medicine team (e.g., team physician, athletic trainer, physiotherapist) to recognize and understand the need to implement evidence-based best practices for the prevention, recognition, and management of this condition. The sports medicine team should have the autonomous and independent authority to make the necessary medical decisions to ensure survival from EHS without organizational conflicts that may stem from lack of understanding and/or support from coaches and administrators [22]. For example, coaches and administrators may perceive the reduction in training duration or exercise intensity due to high environmental heat as hindrance to their planned training schedule. In the secondary school setting, athletic directors may oppose the use of rectal thermometry in minors from perceived uneasiness about the topic. These misconceptions and apprehensions are common unless the sports medicine team initiates the proper dialogue to inform and educate them of the current medical standard of care of this condition. Therefore, the sports medicine team should work collaboratively with coaches and administrators to cultivate a cultural norm that supports the need to implement evidence-based best practices [33]. This may require persistent education on appropriate EHS management practices to the nonmedical stakeholders of the athletic team (e.g., coaches, administrators, parents). Use of policy statements by various governing organizations (e.g., state high school association, state legislation, sports medicine advisory board of a sport association) that are developed using recommendations established by the leading sports medicine associations (e.g., American Medical Society for Sports Medicine, American College of Sports Medicine, National Athletic Trainers’ Association) may help facilitate this process, especially when they are required to be followed by the former entities [10, 18]. Following current guidelines that are endorsed by sports medicine associations will also ensure that these guidelines are based on current best practice and evidence.


Several consensus statements have been published to address the need to implement best practice policies pertaining to EHS prevention and management [20, 34, 35]. In 2017, Huggins et al. [36], summarizing position statements published by the National Athletic Trainers’ Association [1] and the American College of Sports Medicine [11], outlined the best safety practice recommendations for EHS management in youth athletics’ settings (Table 9.2). These recommendations can serve as the foundation for local policies, if evidence-based best practices have yet to be adopted.
Nov 7, 2020 | Posted by in SPORT MEDICINE | Comments Off on of Exertional Heat Stroke in Athletics: Interdisciplinary Medical Care
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