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Exertional heatstroke (EHS) management for sports medicine professionals
This is an excerpt from Acute and Emergency Care in Sports Medicine 2nd Edition by Katie Walsh Flanagan,Patrick Sexton.
Heat-Related Emergencies
Many heat-related illnesses are possible, ranging from muscle twitches to fainting to exertional heatstroke (EHS). EHS is the only true heat-related life-threatening emergency, and it is the only heat illness discussed here. As the name suggests, EHS is brought about by the combination of exertion (working out), temperature (including air and humidity), and other factors. A person can acclimate to hot weather if given the time and if the duration of activity in the hot environment is cautiously and slowly increased. Heatstroke is preventable in many aspects if a person pays close attention to the weather (air temperature, ambient temperature, humidity, wind, sunshine), heat and humidity trends in the local area, clothing and equipment worn, the work-to-rest ratio, and hydration and food intake.16 Other salient factors include medical conditions, body mass, poor conditioning, medications, a prior history of heat illness, and other predispositions that can exacerbate heat illness.16
Signs and Symptoms
If the weather is hot or humid, be suspicious of EHS for any athlete who presents with any of these signs or symptoms. The 2 cardinal signs of EHS are a rectal temperature higher than 105°F (40.5°C) and central nervous system (CNS) dysfunction (namely, concussion-like behaviors).8 Strictly from an observational standpoint, the athlete may be disoriented, confused, or dizzy, and their performance may be deteriorating. EHS patients tend to have diaphoretic and hot skin. The presence or absence of sweat should not be a deterrent to considering EHS, given other feedback. Complaints of muscle cramping, headache, weakness, or dry mouth are worth continued exploration. Nausea, vomiting, or diarrhea can occur prior to collapse.16,24,25
Sudden collapse, seizure, altered consciousness, or coma can occur and will likely transpire if the patient is not rapidly diagnosed and treated.8,16 Vital signs can diminish with time, especially if the patient is untreated.
A sudden collapse in heat is an indicator of EHS, exertional sickling, or exertional rhabdomyolysis (ER; see chapter 13). Each of these conditions can be fatal if not recognized and treated. Medical staff should know the sickle cell status of each athlete prior to the onset of any activity to ensure proper monitoring. Patients diagnosed with sickle cell disease or sickle cell trait must be carefully supervised in activity. As the name suggests, ER involves a breakdown of muscle tissue, and the chief complaints are related to muscle weakness and muscle pain. Although EHS and exertional sickling and rhabdomyolysis have sudden collapse in common, only EHS patients will have a core temperature (measured via rectal thermometer) of 105°F (40.5°C) or higher.
Field Assessment Techniques
A person who has heatstroke presents with concussion-like symptoms, which include confusion, stupor, dizziness, personality changes, combativeness, or complacency. A rapid decision must be made to assess core temperature using a rectal thermometer to diagnose EHS (figure 17.1). Every minute delay in diagnosing EHS via rectal thermometry is critical.
Immediate Management Techniques
Aggressive, whole-body rapid cooling is critical to mitigate the risk of death due to EHS. Patients are to be immersed (trunk and extremities) in a tub or pool of cold iced water (figure 17.3).16,25,29 Equipment and excess clothing should be removed while the patient is in the cold water, and the patient’s head and neck should be supported to prevent slipping into the water. This will allow cooling to begin while the timely process of equipment removal occurs. The water temperature should be from 35°F to 59°F (1.7°C-15°C), and the water should have continuous movement, from stirring or some other method, to maintain the cold temperature on the body to increase the effectiveness of cooling.16
Katie Walsh Flanagan
Absent cold water immersion, data show that the next best option is the application of wet, iced towels and fans directed at the patient. Remove all equipment and most clothing (all but the undergarments) from the patient, and place cold, wet towels on the chest, axilla, and groin. The towels must be wet and switched often to be of any benefit. Do not ring out the iced towels prior to applying them to the patient. The combination of wet, iced towels and fans is not as effective as cold water immersion. It is imperative to understand that cold water immersion is the most reliable way of treating EHS, and all other techniques are inferior at rapidly lowering core temperature.16
Most patients experiencing heatstroke are semiconscious, combative, or noncompliant with instructions, and forcing fluids is not recommended. The crisis is not one of dehydration but one of thermoregulatory collapse. Immediate cold water immersion is critical to ameliorate the effects of a rising core temperature.
If appropriate, following cold water immersion, an IV treatment may be started. If patients’ mental status deteriorates, or if they initially presented with severe symptoms, IV hypertonic saline (3%-5%) is indicated. This delivery of saline rapidly corrects the symptoms of EHS.8,16,24,25 Chapter 15 contains more information on IV therapy.
Transportation Criteria and Techniques
Patients with a core temperature of 105°F or greater (≥40.5°C) are cooled until their core temperature decreases to 102°F (38.9°C). After reaching this internal temperature, the patient is transported via an ambulance to a hospital. Rapid cooling is so important that some states have enacted laws to cool first, transport second. Specifically, in Maryland, when active cooling for EHS is occurring, EMS are required to wait until the patient’s core temperature is 102°F (38.9°C) before transporting the patient to the hospital. This practice mitigates any on-site confusion in hand-off care of the patient to EMS.
Patients whose physician is on-site during the diagnosis and immediate (within 30 min of diagnosis) cooling treatment may not be required to be transported to a hospital. If the patient is symptom free 1 hour after cooling, at that time the physician can determine whether further medical attention is necessary.16
If a physician is not on-site, all patients diagnosed with EHS via rectal temperature should be transported to a hospital after cooling is complete—that is, when the core temperature measures below 102°F (38.9°C).16
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