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Exertional Heatstroke: Faculty of Sport and Exercise Medicine UK Position Statement
Latest news | March 10, 2014

The Faculty of Sport and Exercise Medicine UK has produced a guide for the immediate recognition and treatment of Exertional Heatstroke in those participating in exercise and sport. Dr Courtney Kipps was one of the authors of this position statement, based on his experience treating heatstroke cases in the triathlon and marathon.

Exertional Heatstroke (EHS) is a severe heat illness, defined as central neurological dysfunction associated with an elevated core temperature, above 40°C, during or after exercise. It is caused by an inability to lose heat appropriately and is more common in warm and humid conditions where evaporation of sweat is ineffective.  It also occurs in cooler environments when endogenous muscular heat production may be high. Unrecognised or untreated, EHS can cause significant morbidity and may be fatal. Even when treated, there is a significant risk of short and long-term complications. Immediate recognition and treatment is therefore vital.

1.The diagnosis of EHS should be considered in any collapsed runner or athlete especially if there are signs of central nervous system (CNS) dysfunction. A clear reliable diagnosis of EHS can be made if these CNS signs are accompanied by a reliable measurement of a core temperature indicating hyperthermia (greater than 40°C). Rectal temperature measurement is therefore mandatory in any collapsed or confused runner. A rectal temperature is the most accurate core temperature: peripheral methods of temperature measurement, including aural thermometers, may give erroneous readings and cannot be relied upon. 

2. Medical staff should be aware that EHS may present with paradoxical signs of shivering and peripheral shutdown and that EHS can occur even in cool conditions. 

3. Heat stroke is a medical emergency and rapid onsite cooling intervention is required.  Ice water immersion is the most effective method of cooling a hyperthermic patient but can be difficult to achieve when trying to protect the airway or gain intravenous access. Stripping the athlete, soaking with water and continuous fanning are also effective. Wrapping the athlete in wet towels combined with fanning is an alternative. If the athlete is unconscious, immersing their hands and feet in cool water can also be used as an adjunct. Simple cooling by placing ice bags close to the major arteries (axillae, groin and neck) is significantly less effective than immersion. 

4. The aim of treatment is to reduce further metabolic heat production as quickly as possible and prevent organ damage. Targets for treatment should be a resolution of confusion and a core temperature below 39°C.  There is a risk of hypothermia during cooling treatment which may cause further metabolic heat production through the onset of shivering therefore regular core temperature monitoring (for example, with an indwelling thermistor) is important. 

5. Patients with prolonged symptoms, despite onsite cooling, should be transferred to hospital. 

6.  Field and hospital medical teams should be aware of the complications of EHS, many of which may not be evident in the field hospital setting and may present later, commonly in the first 24 to 48 hours, even if patients appear to recover rapidly at the initial presentation. Initial blood biochemistry within several hours of collapse is often normal and may require repeating. The complications can include rhabdomyolysis and neuro-cognitive dysfunction, as well as renal, liver and multiple-organ failure. Neuro-cognitive dysfunction includes disorientation and confusion, which may be chronic. Even if asymptomatic, EHS patients should be followed up to ensure resolution of biochemical derangement.

7. Patients should be educated that after one episode of EHS, there is a risk of further episodes. Heat tolerance testing may be useful, where facilities exist. 

8. Those suffering from EHS are advised to avoid all exercise until they are asymptomatic and laboratory investigations have returned to normal. Return to exercise should be gradual, and under the guidance of their sports and exercise physician or GP.

9. Medical teams should be aware of the rare association with Malignant Hyperthermia (MH) muscle types. If sedation or anaesthesia is required, drugs which are known to trigger MH (for example, suxamethonium), should be avoided.

10. It is vital to ensure that athletes, sports participants and medical staff are fully educated about the potential risks of developing EHS during exercise, as well as the risk factors which may increase the likelihood of developing the condition.

©Faculty of Sport and Exercise Medicine UK

Authors: Dr Edward Walter, Dr Courtney Kipps, Dr Richard Venn, Dr Rob Galloway, Dr James Thing, Dr James Pegrum, Dr Brian Robertson, Dr Rob Galloway, Dr Dan Roiz de Sa
26 February 2014

 Ref: Walter EJ et al. Exertional heat stroke — the athlete’s nemesis. JICS 2012; 13(4): 304 – 308

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