Heatstroke prevention, symptoms, and what you should know from an M Health Fairview expert

Chase Doornink was a freshman in high school when he collapsed during a 5K cross-country race. His mother and coach, Natalie, recalled that temperatures were only in the high 70s – although it was humid and overcast.

Doctors later discovered that Doornink had exertional heatstroke – one of two types of heat-related illness. Heatstroke happens when prolonged exposure to heat causes the body’s cooling system to fail. If left untreated, it can cause brain and organ damage, or even death.

“We often see exertional heatstroke in younger people who are exercising outdoors in hot, humid weather,” said retired M Health Fairview Family Medicine Physician William O. Roberts, MD, MS. “They’re generating heat that their body can’t get rid of. Non-exertional heatstroke is the second type, and it often impacts older people who are gaining heat from the environment.”

Heat exhaustion has some of the same symptoms as heatstroke. It happens when the body is unable to maintain cardiac output and blood pressure due to heat stress during physical activity. The main difference between heat exhaustion and heatstroke? Body temperature is very elevated during heatstroke and the brain and other organs are at risk of failure. When a person has heatstroke, their body can’t cool itself down to safe levels.

What’s the risk of heatstroke? Dew point is one clue

When should you worry about heatstroke and heat exhaustion? It’s not always the heat, it’s the humidity. Dew point is an important factor, Roberts said. The higher the dew point, the more moisture is in the air. When looking at the dew point in Minnesota, here are Roberts’ recommendations for outdoor activity:

If the dew point is 70 or above, avoid physical activity outdoors. If you are active outside, take frequent rest breaks

If the dew point is between 60-69, take precautions when exercising outside. Take at least two rest breaks every hour and drink plenty of fluids when you are thirsty.

If the dew point is below 60, it’s safer to be active outside. However, Roberts has seen exertional heatstroke occur even when the dewpoint is in the 40s.

While dew point is one measure, the risk of heatstroke varies from person to person. That’s why it is important for everyone to know the symptoms of heatstroke and heat exhaustion. If you recognize the warning signs, you may save yourself, a friend or neighbor from organ damage or death.

Warning signs of heatstroke and heat exhaustion

Heatstroke and heat exhaustion share some symptoms. Look out for these warning signs:

People with non-exertional (classic) heatstroke may also have:

People with exertional heatstroke or heat exhaustion may also have:

If you suspect heatstroke, immediately call 911 and begin cooling the person down:

A body temperature of 104 degrees Fahrenheit or higher is also a sign of heatstroke. However, a rectal thermometer is the only way to get an accurate body temperature. Thermometers that go in the ear, under the tongue, or on the forehead may show a normal temperature even if someone is experiencing heatstroke.

If you suspect heatstroke, even if an ear or mouth thermometer measures a normal temperature, call 911 and begin cooling the person immediately. While outdoor activity is a common cause of heatstroke, there is also a risk indoors – especially for babies and young children inside cars or for elderly people in homes without air conditioning.

Early recognition is key to recovery

“When teammates and coaches saw Doornink collapse during the race, they realized that something was wrong and immediately started cooling him after calling 911,” said Roberts, who helped treat Doornink for heatstroke. “That saved him from a prolonged hospital stay and other problems.”

Natalie Doornink recalled that Chase exhibited many of the common heatstroke symptoms. He was unconscious, had rapid breathing, and may have had a seizure. His body temperature was 107 degrees Fahrenheit, although the outdoor temperature was in the 70s. 

“Chase was airlifted to the hospital and stayed there for three days, before we were referred to Dr. Roberts. He promptly diagnosed it as exertional heatstroke and provided care and guidance moving forward,” she said.

Doornink was able to return to running with ongoing care from Roberts. The physician is also a lifelong athlete and often works with running organizations to help ensure safety during races.

“When a person has heat stroke, all their organs are impacted in some way. Doctors must make sure all the organs are functioning well before that person returns to activity," said Roberts.

During Doornink’s first race back on the cross-country team, Roberts told him to “run, not race.” Instead of trying to win, Doornink’s teammates kept him company and made sure he didn’t push himself. Now, his mother Natalie hopes to spread awareness.

“With exertional heat stroke, athletes can get into a racing zone during competition and might not realize something is wrong. There can be a disconnect between the brain and the body,” she said. “Listen to your body, don’t ignore the symptoms. Make sure you’re prepared to help others.”