Why Body Temperature is Essential in Heat Stroke Assessment

Tevan is a freshman football player trying out for an offensive lineman position on the JV squad. He is excited to show the new coaches the skills he learned from his Pop Warner and middle school teams. But, after two hours at the first practice, Tevan collapses against the tent pole during the water break.

Even though his eyes are open, Tevan is not answering questions from the coaches. The athletic trainer is called over from another field. Taking into consideration the August weather, his heat acclimatization’s status, the practice time, and his size; the athletic trainer strongly considers exertional heat stroke. What are the next steps as the AT? Do we really need to know core body temperature, and measure it with a rectal thermometer, even when the cold-water immersion tub is conveniently positioned between the two football fields? Yes, here’s why:

Wrong Differential Diagnosis

Body temperature is essential when making treatment decisions in the critical time after an athlete has collapsed, and can help rule out potential causes.

Brain Injury

The coaches and players aren’t sure if Tevan hit his head during the last drill. The craziness of the first day of try outs, along with pre-season practices in general, create an atmosphere where this key piece of clinical information can be missing. Ruling out a concussion or subdural hematoma will be difficult without a rectal temperature.

In our scenario, Tevan’s lack of response with a head injury prompts that EMS should be called and transport happen immediately. In an exertional heat stroke case, transport should be delayed until cooling below 102°F is complete.

Sickling Crisis

No one knows if Tevan’s collapse against the tent pole is due to a sickling crisis. Sickle cell trait testing is not mandated at the high school level, and family members are not present, so this key piece of information is also lacking. Tevan’s inability to answer questions in a sickling crisis would also warrant immediate transport via ambulance with no delay for water immersion. He would also need oxygen as soon as the ambulance arrives, which is not needed in concussion or heat stroke cases.

Other Possibilities

If our clinical scenario was slightly different, Tevan’s AT would also need to rule out heat exhaustion or possibly hyponatremia. Heat exhaustion can typically be ruled out with a CNS assessment. However, sometimes heat exhaustion cases can have mild dysfunction, such as delayed verbal responses and struggling to make eye-contact.

On the flip side, in some exertional heat stroke cases, the patient is very verbal and is showing dysfunction in other manners which would be hard to ascertain without temperature assessment. Hyponatremia has occurred in high school football previously, both cases resulting in death. Immediate EMS transport while not providing IV fluids is needed, but would be contraindicated for EHS.


Water Immersion

Ice water immersion needs to be initiated immediately with EHS. Without a rectal temperature, an AT will not know how long to immerse Tevan. EMS will arrive and rightfully want to take him away. Reporting that Tevan has heat stroke with only subjective reasonings (it’s hot outside and he has CNS dysfunction) will make EMS understandably antsy. Yet, if the AT can show a rectal temperature receiver that actively shows his temperature going down, this provides EMS with an objective reason to wait.

If EMS takes Tevan too soon and his temperature is still above 104°F, Tevan may die from lack of aggressive cooling or have significant organ damage. This latter situation was the case in a recent media story of a college football player who lost his liver after being pulled too early from the water immersion tub for transport. The goal is to bring an exertional heat stroke victim’s temperature below 102°F to avoid organ damage and hypothermic overshoot. This goal will be quite elusive without a rectal temperature.

Assessing Immersion Timing, Shivering, CNS Return

Some athletes take longer to cool than others, predominately due to larger body sizes, but also possibly due to reasons we don’t know yet. Therefore, Tevan’s AT cannot estimate an arbitrary 10 minutes for his cooling time.

Shivering is not a perfect response during hyperthermic situations. The hypothalamus is constantly receiving feedback from skin/shell versus the core. This feedback can be confusing when there are rapid increases coupled with decreases and water immersion. Research on cooling in hyperthermic patients reports that individuals have varied responses in shivering. It does not reliably show up when cooling is complete, or vice versa.

Return of CNS function is a better variable to assess when determining if body temperature has returned below critical threshold (104°F). The disadvantages of depending on CNS return though, is an increased likelihood of hypothermic overshoot and CNS function not fully returning once cooling is complete. The brain is reacting to a multitude of problems within the body, not just hyperthermia. There have been a few cases in which health care providers report that CNS has not returned once body temperature was lowered to 102°F and transport initiated. Therefore, Tevan’s AT cannot depend on set times, shivering, or CNS return. The AT needs to depend on a rectal temperature.

Return to Activity

When Tevan is cleared by his primary care physician to return to activity, how does the AT know what type of program to use? With no rectal temperature to have confirmed an EHS diagnosis, return to activity becomes clouded.

If a concussion was confirmed, Tevan’s AT can use a return to activity protocol supported by expert consensus. This same protocol could suffice for an exertional heat stroke patient, but will not work if Tevan were to continually fail steps and need further expert help. An EHS patient would also need a different specialty clinic to help in this scenario. However, without the rectal temperature confirming an EHS, how does the AT know for certain it was EHS or concussion?

Similarly, if rectal temperature was taken and EHS ruled out, sickle cell trait might be a lab test ordered at the hospital to determine what had caused his collapse. SCT athletes can be fully competitive but need accommodations for all future practices and additional treatment preparations. Yet, how will Tevan’s AT know if accommodations are needed if not certain of the original diagnosis?


Tevan’s athletic trainer needs to take him to the cooling tent, elicit help to create quick privacy with a towel, and obtain a rectal temperature. The AT can then verify his/her EHS diagnosis, get help putting Tevan into the ice water immersion tub, and watch the receiver as his core temperature decreases. The long flexible probes used today, allow easy, constant monitoring during treatment. When his core body temperature decreases to normal, Tevan’s AT can get help removing him from the tub, and have EMS transport for further care. Rectal temperature provides confidence in an accurate diagnosis, makes water immersion timing objective, and supports return to activity protocols or specialty referrals.

Looking for more? Susan’s new course, Body Temperature Assessment for Exertional Heat Stroke, will be launching soon! Get started with her first MedBridge course on Exertional Heat Illnesses with the short clip below.

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