When things get hot for EMS providers

The scenario: 29-year-old male, muscle cramps

You are working the quick response vehicle (QRV) at a local marathon when a call comes for a medical team to respond to mile marker 20. You start the engine on the QRV cart and proceed over the to aid station. 

When you arrive, you are directed to the tent area where volunteer first aid personnel are gathered around a male patient. According to one of the staff members, the patient staggered into the aid station and collapsed.  He had an initial period of unresponsiveness but is now awake.

The patient’s name is Jeff, and as you walk up he tracks you visually. He responds to your questions by mumbling. Jeff’s skin is flushed, hot to the touch and dry. The back of his race bib is filled out with medical and emergency contact information. Based on the information he provided, Jeff appears to have no chronic medical conditions, take no prescription medications and has an allergy to penicillin. 

Heat emergencies can be expected throughout the year across the country but are especially prevalent in the summer particularly during sporting events. Like most other environmental injuries, heat emergencies are treated by reversing the cause of the condition. The aggressiveness of cooling a patient is dependent on how severe the heat emergency is.

The National Institute for Occupational Safety and Health (NIOSH) at the Centers for Disease Control, characterizes heat emergencies into four categories.

The most serious condition, heat stroke, is characterized by high body temperature, altered level of consciousness and dry skin. In heat stroke, the body has lost its ability to regulate temperature as sweat is no longer being produced. 

Heat stroke is a life threatening condition treated by actively cooling the patient by wetting the body after moving him to a cool area and removing constricting clothing. 

The next heat emergency is heat exhaustion. This occurs when the body has lost significant amounts of fluid and electrolytes through sweating. Patients will present with excess sweat, dizziness, nausea, warm, clammy skin and cramps. 

Patients with heat exhaustion should be moved to a cooler setting and given oral fluids if they are able to drink them on their own and can maintain a patent airway.

Heat syncope occurs when a patient changes position quickly and either loses consciousness or experiences dizziness while in a hot environment. This condition is often the result of dehydration after exertion in a hot climate. These patients should be moved to a cool location and encouraged to lie down.  Additionally, they should be given cool fluids to drink if it is safe to do so. 

Finally, heat cramps are muscles spasms that manifest as a result of an electrolyte imbalance brought on by sweating. Generally these cramps are treated by removing the patient from the hot environment and allowing time to rest.  As above, cool fluids may be given orally if it is safe to do so. 

Treatment for all types of heat emergency includes cooling the patient, actively or passively depending on the severity of the presentation. Also, patients may benefit from increasing the intake of oral fluids.  While water is a good option, it is important to remember that sweating causes the body to lose both fluid and electrolytes.  For these patients, giving a sports drink rather than regular water may be indicated. 

Among sports medicine physicians, there is an additional type of heat emergency called exertional heat stroke (EHS).2 EHS is characterized by mental status changes (possibly after a period of consciousness) and core temperature of 104°F or higher. EHS is caused by a group of influencing factors including hydration status, level of exertion, environmental factors like temperature and humidity and how acclimated the patient is to the surrounding environment. 

EHS can have a rapid onset and does not necessarily represent a progression from heat exhaustion to heat stroke to EHS. A patient may have only minor heat cramps prior to collapsing at an event.

Increasingly, cold water immersion is being used to treat patients suffering from EHS.3 The goal of this treatment is to rapidly lower the core body temperature (measured by rectal probe) to below 104°F within 30 minutes of symptom onset. While traditionally there have been concerns about shivering actually increasing core body temperature, studies show that while “normal” patients will shiver when placed in cold water, patients suffering from EHS will not. 

After treatment, it is recommended that patients not return to activity immediately and gradually work their activity level back up after a week. 

Ensuring that he has a patent airway, you move Jeff to the stretcher and onto the golf cart.  On your way to the medical tent, you remove his shirt and wet down his skin. The patient presents as hypotensive with a weak and rapid radial pulse.  At the first aid station, the sports medicine physician for the marathon assesses a rectal temperature which is 109°F. 

The patient is immersed in cold water 15 minutes after his initial loss of consciousness. During his cooling, the patient receives cool IV fluids. After his core temperature stabilizes at 101°F, he is transported to the local ED for further evaluation.

One week after the marathon, Jeff is back to his training running short distances in an air-conditioned gym.  He has another marathon scheduled in two months and, in conjunction with his physician, will be planning to acclimatize to the heat well in advance of the race.

Note: Consult with medical direction before performing any treatments outside of standing orders currently in place.


  1. "Heat Stress." NIOSH. Centers For Disease Control, 23 May 2013. Web. 1 July 2013. <http://www.cdc.gov/niosh/topics/heatstress/>.
  2. Casa, Douglas J., Lawrence E. Armstrong, Matthew S. Ganio, and Susan W. Yeargin. "Exertional Heat Stroke in Competitive Athletes." Current Sports Medicine Reports 4(2005): 309-317.
  3. Casa, Douglas J., Lawrence E. Armstrong, Brendon P. McDermott, Elaine C. Lee, Susan W. Yeargin, and Carl M. Maresh. "Cold Water Immersion: the Gold Standard for Exertional Heatstroke Treatment." Exercise and Sports Sciences Review 350.3 (2007): 141-149. 

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