How does extreme heat affect your body? Here's what we know

The human body is not designed to withstand life-threatening temperatures of 118 degrees Fahrenheit, which are predicted in Arizona this weekend on top of weeks of oppressive heat taking over Asia, Europe, and the US.

According to NBC, local doctors shared that patients have already been arriving in Phoenix emergency rooms with organ failure, sunburn, or comas brought on by the intense heat.

Dr Aneesh Narang, an emergency medicine specialist, reports that patients with body temperatures as high as 109°F are "unresponsive" and "cooked" due to disturbances in cooling mechanisms, including the brain's hypothalamus, which controls temperature, making the heat deadly.

“You’re kind of cooking from the inside, unfortunately," Narang said.

The typical range of a normal body temperature is 97 to 99°F. In contrast, an infection-related fever typically rises above 100.4°F while 104°F or higher is the threshold at which heatstroke occurs.

“We are seeing quite a few heat-related illnesses,” said Dr Amy Axberg, an emergency medicine physician at John C. Lincoln Medical Centre in Phoenix. “My patient yesterday had a temperature of 107°F — that’s a heatstroke, and that’s an emergency.”

Heatstroke and heat exhaustion can cause severe symptoms, including mental changes, coma, and seizures, while high temperatures can cause organ failure and inflammation.

Rapid cooling using a thermometer to monitor body temperature helps save lives during heat illness calls. Axberg shared that she treated a patient in the ER with the help of an ice bath.

Narang suggests doctors must promptly reduce a patient's temperature to prevent catastrophic effects on organs and recovery. Although the heat has not reached its peak yet, he believes July and August are the toughest months in the area and predicts worsening conditions in the coming months.

Record-breaking temperatures are causing heat exhaustion and heatstroke patients to visit the ER, affecting young and healthy individuals who typically engage in outdoor activities that can cause headaches, nausea, and fast heartbeats. According to Narang, poor hydration can cause rapid health issues, regardless of overall health.

Medications can block warning signs

Narang said that psychiatric medications, like antidepressants, can mask warning signs of heat-related issues as these medications work on the hypothalamus, which regulates temperature, preventing sweating.

However, doctors advise patients not to stop taking prescribed medications due to the heat, as they believe it is crucial to monitor the hypothalamus's function to prevent potential issues.

The emergency room doctors claim that although they are concerned about the 110°F temperatures expected across the region on Saturday and Sunday, their emergency rooms are not currently at capacity as they were during COVID-19.

“In general, we’re doing OK, but during the heat of the day, it can often become overwhelming with the number of patients that are coming in,” said Dr Brian Hess, an ER medical director at multiple emergency departments at Abrazo Health in Arizona. “We’re having to accommodate higher volumes of EMS traffic during those high heat periods.”

Meanwhile, Hess warns that individuals with substance abuse disorders or housing issues may not recognise dangerous physiologic conditions like heat exhaustion or heart failure and suggests caution for patients with dementia and heart failure who are advised to drink fewer fluids.

Stages of heat exhaustion, heatstroke

The first signs of heat exhaustion can appear in as little as 15 minutes at triple-digit temperatures, according to Hess. Depending on risk factors, the onset of symptoms for more severe heatstroke typically takes a few hours.

The Centres for Disease Control and Prevention warn that once a heatstroke begins, body temperatures can rise to 106 F in as little as 10 minutes.

Early signs can include dizziness, nausea, heart palpitations, heat cramps, or severe muscle spasms as a result of salt and water loss after exercise, most frequently in the hands, calves, and feet.

“More severe signs are changes in your mental status,” Axberg said. “You could be getting confused, slurring your speech or just don’t feel like your normal self.”

While it’s best to stay indoors as much as possible, if people go outdoors, hike or play a round of golf, hydrating is a great way to stay ahead of potential trouble.

“I always recommend a glass of water before you drink your cup of coffee in the morning to prevent dehydration from kind of catching you off guard,” Hess said.

One of the misconceptions about dehydration is that thirstiness can indicate dehydration. “That’s not true,” Narang said. “By the time you’re thirsty, you’re well behind the eight ball.”

However, early treatment of heat-related illnesses can lead to recovery. A patient with a 107°F body temperature is now eating and drinking, according to Axberg,  demonstrating the effectiveness of rapid cooling in treating heatstroke.