As temperatures and humidity outside soar, what’s happening inside the body can become a life-or-death battle, just a few degrees apart.
Researchers who put people in heat boxes to see what happens to them say the critical danger point for illness and death from extreme heat outdoors is several degrees cooler than experts once thought.
As much of the U.S., Mexico, India and the Middle East suffers from sweltering heat waves made worse by human-caused climate change, several doctors, physiologists and other experts explained to The Associated Press what the human body does in such hot weather. what happened.
critical body temperature
The body’s resting core temperature is usually about 98.6 degrees Fahrenheit (37 degrees Celsius).
Ollie Jay, professor of heat and health at the University of Sydney in Australia, who manages the thermal ergonomics laboratory, said that this is only 7 degrees (4 degrees Celsius) away from the disaster caused by heat stroke.
Dr. Neil Gandhi, chief of emergency medicine at Houston Methodist Hospital, said during a heat wave, anyone with a fever of 102 degrees or higher and no clear source of infection is checked for heat exhaustion or a more severe form of heat stroke.
“During certain periods of high temperatures, we typically see core temperatures above 104 to 105 degrees,” Gandhi said. Any more than one to three degrees above that, he said, puts such patients at high risk of death.
How heat kills people
Jay said there are three main ways high temperatures cause death. Usually the first suspect is heat stroke – a sudden increase in body temperature that leads to organ failure.
When the internal temperature gets too hot, the body sends blood toward the skin to cool it down, Jay said. But this diverts blood and oxygen away from the stomach and intestines and can cause toxins normally confined to the intestinal area to leak into the circulatory system.
“It sets off a cascade of effects,” Jay said. “Blood clots develop around the body, leading to multiple organ failure and ultimately death.”
But Jay says the bigger killer of the heat is the stress on the heart, especially for people with cardiovascular disease.
Again, blood rushes to the skin, helping to dissipate core heat. This causes blood pressure to drop. The heart responds by trying to pump more blood to prevent you from passing out.
“You’re asking the heart to do more work than usual,” Jay said. For people with heart disease, “it’s like running for the bus with a dangerous (hamstring). Something is going to give.”
The third major pathway is dangerous dehydration. When people sweat, they lose fluid, which can put severe stress on the kidneys, Jay said.
Gandhi, of Houston, said many people may not realize their dangers.
Dr. Renee Salas, a professor of public health at Harvard University and an emergency room physician at Massachusetts General Hospital, said dehydration can develop into shock, causing organs to shut down due to a lack of blood, oxygen and nutrients, leading to seizures and die.
“Dehydration, if severe, can be very dangerous and even fatal for everyone, but it is especially dangerous for those with existing health conditions and those taking certain medications,” Salas said.
Dehydration can also reduce blood flow and worsen heart problems, Jay said.
Attack the brain
Heat also affects the brain. Several doctors say it can cause a person to become confused or have trouble thinking.
“The first symptom that you’re in trouble in the heat is if you’re confused,” said Kris Ebi, a professor of public health and climate at the University of Washington. “That’s not helpful as a symptom,” she said. Because people suffering from heat stroke are less likely to realize this. This becomes a bigger problem as people age.
W. Larry Kenney, a professor of physiology at Penn State University, said that one of the classic definitions of heat stroke is a core body temperature of 104 degrees “combined with cognitive impairment.”
Humidity is important
Some scientists use a sophisticated measure of outside temperature called wet-bulb temperature, which takes humidity, solar radiation and wind into account. In the past, it was believed that problems began when the wet-bulb temperature reached 95 degrees Fahrenheit (35 degrees Celsius), Kenney said.
His tests showed the wet-bulb danger point was close to 87 (30.5 degrees Celsius). He said that number is already starting to appear in the Middle East.
This is only suitable for young and healthy people. He said the danger point for older people is a wet-bulb temperature of 82 degrees Celsius (28 degrees Celsius).
“Wet heat waves kill many more people than dry heat waves,” Kenney said.
When Kenney tested young and old in dry heat conditions, young volunteers could function at 125.6 degrees (52 degrees Celsius), while older volunteers had to stop at 109.4 degrees (43 degrees Celsius). He said people wouldn’t be able to work in temperatures nearly as high in high or moderate humidity.
“Humidity affects the ability of sweat to evaporate,” Jay says.
Quickly cool down the patient
Salas said heat stroke is an emergency and medical staff will try to cool the victim within 30 minutes.
The best method: cold water soaking. Basically, Salas said, “you throw them in a bucket.”
But these are not always present. So the emergency room will give patients cold fluids intravenously, spray them with a spray, put ice packs in their armpits and groin, and then place them on a cooling pad with cold water running through it.
Sometimes it doesn’t work.
“We call it the Silent Killer because it’s not a visually dramatic event,” Jay said. “It’s insidious. It’s hidden.
