David Della-Giustina knows what it's like to be in extreme heat.
A retired U.S. Army colonel with more than 29 years of service, he did combat tours in Afghanistan and Iraq, where he often endured extreme temperatures while serving as a physician.
"We train a lot for being in the heat as well as the cold and how to deal with it, as well as how to manage casualties and how to protect ourselves," said Della-Giustina, who is now a professor of emergency medicine at Yale School of Medicine, where he is also vice chair for education of emergency medicine and program director of the Wilderness Medicine Fellowship.
But you don't have to be deployed overseas to encounter extreme heat. Extreme temperatures have become increasingly common in the U.S., for instance, especially during the summer, and are expected to become even more frequent and intense in the coming decades due to climate change.
As the temperatures rise, so does the risk to people's health, posing a host of dangers, from heat exhaustion to heat stroke.
In an interview, Della-Giustina discusses common heat illnesses, when a person should seek medical help, and how to reduce risk.
The interview has been edited for length and clarity.
What are some of the most common heat illnesses?
David Della-Giustina: Heat illness is a gradation of how sick someone gets from the heat. There's mild heat injury where someone gets a little overheated. They're a little sweaty. They may be a little dehydrated. They feel a little weak. But they're not very symptomatic with it. Then it goes to heat exhaustion, where essentially someone is overwhelmed by the heat. Their body temperature may become mildly elevated, and they may have a low-grade fever, but not a high fever. They feel weak, they feel dizzy, and they can't do the regular activities that they need to do. They're also sweating profusely, depending on what their other medical problems are.
Then it goes to the more severe form, which is heat stroke. Heat stroke occurs when someone has a heat injury or heat exhaustion, plus they have altered mental status, so they are confused or they're comatose. They have difficulty walking or doing anything themselves. They're stumbling if they're walking at all.
One of the misnomers about heat stroke is that in order to be defined as heat stroke, a person has to stop sweating. That's actually not true. Most of the victims of heat stroke are still actively sweating. It's just that their temperature goes up, and because they're so hyperthermic their brain does not work very well. The enzymes and proteins in the brain do not work well, so they have an altered mental status.
What are the signs of heat illnesses?
Della-Giustina: Dizziness or lightheadedness, nausea and some vomiting, headaches, and fatigue are some common symptoms. Then, as people get sicker, they start to become slower to respond. They become confused. They have difficulty walking.
Who is most at risk of getting a heat illness?
Della-Giustina: There are really two groups of people who are at risk. The first group, and the one that we see more commonly in the emergency department, is people who are outside working or doing activities. Typically, it's people who are laboring outside in the heat, and they're not able to get the rest that they need. Along with them are those performing athletics. They're at sports practices or they're running or exercising outside in the heat.
The second big group is people who can't get themselves out of the heat or get to an area that's cooler, and that's typically the elderly, people who are more immobile, people who don't have air conditioning, and people who have medical problems such as congestive heart failure, diabetes, or hypertension where they're taking medications that dehydrate them.
When should people seek medical help?
Della-Giustina: Generally, they should seek medical help if they're experiencing any confusion, altered mental status, difficulty walking, passing out, or throwing up to the point where they can't keep anything down. Those individuals should seek medical help.
How can people reduce their risk of heat illnesses?
Della-Giustina: Number one is making sure they stay well hydrated. Staying hydrated the day before you do something outside is really important. Those who are dehydrated the day before are more likely to have a heat injury.
Once you're in the heat, make sure you take time to rest. If you start to feel a little overwhelmed, get a headache or feel nauseated, you should slow down what you're doing, get into the shade, and try to get into a cool area or out of the heat. For people who are out in direct sunlight, it seems unusual, but wearing a hat and lightweight, loose-fitting long-sleeved shirts and pants can actually help protect against direct sun exposure and reduce heat absorption. While it may seem counterintuitive, this clothing acts as a barrier against the sun and can help keep you cooler than exposing your skin directly to intense sunlight.
