Icy Water, Cold Air Gusts Test Survival Clothing
Brian Cress hops into a large pool filled with fast-moving ice water in the basement of the University of Minnesota-Duluth Medical School whenever he gets the chance.
It isn’t that he loves being cold, he acknowledged. It’s the money he gets for being a guinea pig in the school’s Hypothermia Research Laboratory, which tests protective clothing and conducts basic scientific research on the body’s reaction to cold.
“It’s good pay. Also it helps with improving the suits, making sure people are going to survive in the suits,” said Cress, a sophomore medical student who has been a test subject for nearly two years, getting $100 every time he spends from one to six hours in the frigid water coursing through the 2,500-gallon pool.
Cress also volunteers as a subject for studies of cold air, for which he gets $25 for spending time in a walk-in freezer--sometimes wearing only shorts and sometimes in survival suits.
“I prefer the water studies,” he said. “Cold air is incredibly uncomfortable. The fan blows the cold air across my chest and it feels like I’m iced down.”
The laboratory, one of the few cold-weather research centers in the world, got its start about eight years ago because there was no facility in the United States for testing the effectiveness of survival gear, said Dr. Robert Pozos, who heads the medical school’s physiology department and is one of the laboratory’s directors.
Tests are still conducted on survival suits such as those worn by oil workers in the Atlantic Ocean and North Sea, U.S. Coast Guard and Navy personnel and other seamen.
However, the laboratory also is doing basic research on such diverse topics as effects of cold-water exercise on patients with multiple sclerosis, how water currents affect the speed with which hypothermia sets in, why young children sometimes survive under water for long periods, how shivering affects body heat, and the effects of alcohol on body functions in cold temperatures.
Some Tests Done in Lake
Most water tests are done in a constant-current $25,000 pool donated to the laboratory this summer by Swimex Systems Inc., of Warren, R.I., but some tests are still done in Lake Superior.
“I feel more comfortable doing testing in the pool, for safety reasons. On the lake, you can’t have equipment to monitor heart rate, temperature,” said Larry Wittmers, a laboratory co-director.
“This is much colder than Lake Superior,” Cress said of the laboratory pool. “But it’s not too bad. You get your body psyched up. I have to prepare myself to do it.”
Bryan Delage, a third-year medical student at the University of Minnesota Medical School in Minneapolis, recently traveled to Duluth for his ninth stint in the cold water to test a deck suit designed for workers on ocean oil rigs, ore carriers and Coast Guard vessels.
“Sometimes it’s all right. Without the suit, those tests are a little more intense,” Delage said as technicians attached wires to his skin to provide a constant computer readout of changes in his skin and body-core temperatures and heart beat.
The experiment was designed to determine how much water current, simulated by a motorized, variable-speed paddle wheel, will increase heat loss, Pozos said.
“He’d have 30 minutes in this water (50 degrees Fahrenheit) without the suit before hypothermia would set in,” Pozos said.
Delage said he would prefer a suit with mitts. “If you get your hands wet it can be very painful,” he said as he lay shivering with his hands raised above the surface of the water.
After 28 minutes in the pool, Delage’s skin temperature had dropped six degrees, but his core temperature had not fallen.
Suit Does Its Job
“He’d be in real trouble without that suit. It’s doing exactly what it’s designed to do,” Pozos said.
Suits alone sometimes may not be enough to protect a person from hypothermia in a stressful situation, said psychologist Richard Hoffman. Anxiety also may play a big part in the onset of hypothermia, he said.
“The heart rate goes up when subjects are tested in the lake. We feel anxiety probably drives temperature down,” Hoffman said.
He also noted that people are very poor judges of how cold they are and said being in tremendous physical shape does not seem to help much in fighting off hypothermia.
Alcohol in the bloodstream can have serious effects, even though recent research indicates that drinking does not impair the body’s cold defenses, Hoffman said.
Alcohol Impairs Thinking
“Alcohol did impair people’s ability to think. People who were drunk and in the cold did worse than people in warm air who were drunk,” he said. “I think this shows the biggest risk for people drinking who are in the cold is impaired judgment rather than drop in core temperature.”
Researchers also have begun looking at the effect of cold core temperatures on memory.
“We’re just starting this. One British study indicates people start to have trouble remembering at about core temperature 95 degrees Fahrenheit (normal body temperature is 98.6 degrees),” Hoffman said.
“This may be a real risk factor for divers, cross-country skiers, hikers. Are they going to have problems remembering how to get back? We know that if you take a person’s core temperature down low enough they will start to get confused,” he said.