Heat-related illnesses: When to seek medical care

July 2021 was earth’s hottest month ever recorded, according to the National Oceanic and Atmospheric Administration (NOAA). With global warming and an increased ambient temperature, NOAA scientists say heat waves are bound to continue.

As a result, heat-related illnesses will increase, making awareness of their symptoms paramount for all of us.

“There’s several gradations of heat injury depending on which part of the body is affected,” said Nathan Rudman, MD, medical director of the Cape Cod Hospital Emergency Center. “The military has certain definitions and the athletic associations also do, but basically it ranges from mild to severe illness.”

Dr. Rudman defined the gradations as follow:

• Heat cramps are the lowest on the scale and they are exactly what they sound like – muscle cramps or spasms caused by exercising in the heat that can lead to low salt levels in the blood.
• Heat syncope is when a person faints or experiences extreme dizziness due to heat. Dehydration exacerbates this condition.
• Heat exhaustion occurs when the body sweats excessively. It causes dizziness, weakness, and an elevated body temperature.
• Heat injury is when being overheated causes organ injury without a mental status change.
• Heat stroke is the most serious heat-related illness, and symptoms include a high temperature, dizziness and a change in mental status. When this happens, the body is unable to control its temperature and body temperatures can go as high as 105 degrees.
• Rhabdomyolysis is a breakdown of muscle tissue that releases a damaging protein into the blood. It can lead to kidney failure and cardiovascular collapse.

As you go up the gradation you go from less serious conditions to more serious ones, and there is a risk of organ injuries such as damage to kidneys, the liver and the central nervous system, Dr. Rudman said. Those with heat injury, heat stroke and rhabdomyolysis are at risk of dying if they aren’t treated.

“I honestly think nowadays that anybody with any altered mental status from the heat needs to come to the ER,” he said. “Probably really anybody other than those with heat cramps should seek care after they hydrate up. With heat exhaustion, if you’re just feeling weak and lightheaded and you’ve been out in the heat, go to a cool place, hydrate up and if you are not better in a half an hour or an hour, you should probably go to the ER.” 

Urgent care is another option for heat exhaustion, but anyone with symptoms of high temperature, fainting, confusion, muscle aches or anything else that would indicate organ failure should head straight to the ER.

The people with the highest risks include runners in marathons, athletes, police recruits and military recruits, especially if they go from being unconditioned to all of a sudden having to strenuously train and work out.

The two most important factors causing heat-related injuries, according to Dr. Rudman, are

• Lack of previous conditioning
• Temperature.

When he was in the military, they used something called wet bulb globe temperature as a guide to working out in direct sunlight. It is a combination of not just temperature but also radiant heat and humidity. These factors matter because they influence the ability of the body to sweat in order to cool off.

If the temperature is 100 degrees in a region that is arid with low humidity, your body uses evaporation through sweating to cool down. In a region that is the same temperature but with high humidity your body is much less able to sweat to cool down because the sweat can’t evaporate. That makes it more dangerous.

Treatment depends on the gradation of the heat-related injury.

“For the lower gradations, getting out of the heat, and giving the patient fluids either orally or through IV usually does the trick,” Dr. Rudman said. “When you get to the upper gradation, like heat injury or heat stroke, rapid cooling is the most important thing.”

Rapid cooling can be done by putting the patient in an ice bath, wrapping them in ice cold towels or spraying them with tepid water and putting a fan on them. You can also apply an ice pack to the groin and axilla (armpit area) – places where the skin is close to large blood vessels, he said.

“The key with the more severe gradations is to do rapid cooling wherever you are,” he said. “You would do it before you transport someone. You don’t put them in an ambulance and send them to the ER. You put them in an ice bath first and then send them to the ER afterwards when they are cooled down.”