April 12, 2001 -- You'd think swimmers in balmy Miami wouldn't need to fear the cold.
In fact, though, even in the summertime the emergency room at Miami's Baptist Children's Hospital treats three or four children a month for hypothermia -- a condition that results when the body's temperature falls significantly below normal.
"Even though we have mild water here, we still do see kids with lowered core body temperatures every summer," says Francisco Medina, MD, director of emergency services at the hospital. "The water in this area is about 75 to 80 degrees, while normal body temperature is 98.6 or so, so that's still quite a difference. Young people have a greater surface area in proportion to their body mass, so they're at increased risk for heat loss."
Most of the children who come into the emergency room with hypothermia have prolonged exposure combined with a fall or some other trauma or accident in the water. Milder cases can be treated at home -- just wrap the child warmly.
"Take their temperature rectally, because you want to measure core body heat," Medina says.
Competitive athletes and others who swim in lakes, rivers, or the ocean also can lose too much body heat, without realizing it. And it's impossible to say exactly how long is too long, says Jamie Musler, MS, ATC.
"Everyone reacts differently. People who are better trained and more fit can last a longer time in a cold environment. People with a higher percentage of body fat tend to maintain body temperature for a longer time," says Musler, athletic training program director and coordinator of clinical education at the Bouve School of Health and Athletic Training at Northeastern University, in Boston.
Organizers of competitive swimming events need to stay alert to potential signs of distress, Musler says.
"Athletes tend to be highly motivated people, and because they're so focused on performance they may override warning signs of hypothermia. At distance-swimming events there should be well-designed emergency procedures in place. Observers should watch for changes in swimming patterns to identify when someone may be in trouble."
As the body cools, blood moves to the central organs to maintain core temperatures. This means hypothermic swimmers may get numb fingers and toes, which affects their ability to grasp objects. As the brain receives less oxygen, the swimmer can become confused and disoriented, so someone who's in need of rescue may not follow directions well.
If someone is shivering and has blue lips, but no other problems, they just need to be warmed, Musler says. But don't put them in a warm shower or tub.
"In the field, use blankets and clothing to maintain body temperature. Once they're indoors, you may sit them in a warm room, but not right next to a heat source. Use normal temperature blankets at first, and then perhaps use warmed blankets. Rewarming should be a slow, steady, gradual process."
Give them lots of lukewarm liquids, says Todd Schlifstein, MD.
"Hydration is very important to help get rid of muscle metabolites that are formed when you shiver a lot," says Schlifstein, a clinical instructor at New York University Medical Center.
However, if someone is so cold they can't stand or move their limbs normally, if they don't know who they are or where they are, those are signs of more severe loss of function.
"In that case, it makes sense to go to an emergency room, where trained people know how to deal with this situation," Musler says.
"Or when you try normal rewarming measures and the person continues to shiver and doesn't improve, take them to the emergency room," he says. "In some cases of hypothermia the body cannot rewarm itself."