Fifteen years ago, Stanford biologists Craig Heller and Dennis Grahn were joking around with an anesthesiologist friend of theirs. Heller and Grahn had been studying how mammals regulate body temperature, and their friend threw down a challenge. “If you guys know so much,” the friend prodded. “Why can’t you solve this problem in the recovery room?”
The doctor’s problem was that patients lose a lot of body heat when they’re under anesthesia, and once they come back to it’s really hard to warm them up again. In order to retain as much internal heat as possible, the body’s natural response to cold kicks in. The network of veins—the same ones that transport heat from our core to our skin when we’re hot—clamps up when we’re chilly. Getting patients to warm up is a long and potentially problematic process. “When patients come out of anesthesia, they shiver like crazy and they rip stitches,” the doctor told the pair of biologists.
When Galileo invented the first thermometer in 1592, for the first time in human history it became possible to put internal temperature fluctuations on a measurable scale. Eventually we learned about the human body’s ability to self regulate—to hover close to 98.6 degrees Fahrenheit in order keep our organs healthy, no matter the external environment.
But sometimes those powers of self-regulation work too well for our liking. If we run too hard or exercise in prolonged heat, for instance, our bodies will automatically shut down to prevent us from overheating. It might be annoying, but our bodies have our best intentions at heart; they’re programmed to avoid things that will cause, you know, cell damage and organ failure.
If only we could figure out how to influence our bodies to bring down our internal temperature, we would be able to run an extra mile—or warm up fast enough not to rip out our stitches.
For a century we’ve tried all sorts of nutty things to try to hack our internal thermostat.
For a century we’ve tried all sorts of nutty things to try to hack our internal thermostat so we can work longer, run harder, and recover faster. A patent granted in 1882 details how a flexible metallic tube wrapped around a foot or knee might be effective. By dumping warm or cold liquid into one end, this sort of straw-shaped hot (or cold) water bottle could nudge body temperature during “medical or chirurgical” interventions. In a patent granted in 1935, a safari hat outfitted with an evaporation plate and either “volatile etheric oils” or dry ice claimed to simulate the effect of “dipping the hands and arms into a basin of cold water”—but without the basin. A head-mounted vessel filled with a coolant (with an accompanying cheese cloth face curtain) was patented in 1961 as a solution to help people working outdoors. In 1970, there was even plug-in body suit rigged with heating and cooling coils that was patented for medical use.
Alas, the ideas didn’t stick. And as recently as fifteen years ago, there was still no solution for something as simple as warming someone under the close supervision and constant care of an anesthesiologist.
So after the recovery room challenge was proposed, Heller and Grahn hacked together an experiment. Using a piece of welding duct, a heating pad, a wet suit sleeve, and a vacuum pump, they fashioned themselves a jury-rigged apparatus that could be tested in the recovery room. A sort of temperature regulating gauntlet.
Typically, patients take an hour or two to re-warm after being put under. After being secured to a patient’s arm, Heller and Grahn’s makeshift device did the same work in less than ten minutes. They were shocked—and even more so considering they didn’t know why exactly it worked so effectively.
Their early experiments led the team to two discoveries. First, they learned that their device was sending heat to the critical organs, not the whole body. And second, even though their initial prototype covered quite a bit of the arm, its presence over the hand was all that mattered.
What was happening was that they were taking advantage of a network of special veins that act as heat exchangers present behind non-hairy skin surfaces—the palms, feet, and face for humans. “On a cold morning your hands are really cold, but you start running and in five minutes your hands are really hot,” says Heller. “That doesn’t happen everywhere on your body.” The veins open up when we’re hot and our palms act as radiators, and in the cold, they constrict to keep the warmth in.
Heller and Grahn were taking advantage of that direct channel to the organs, and pumping up its effectiveness by employing a vacuum. The vacuum pulled more blood into a patient’s hand, which improved the heat transfer.
And as their research continued, they realized perhaps they could use the same process, but in reverse. So they built a glove with a vacuum that could send cold to the core.
As the experiments with what’s now called the CoreControl started they were working with a lab technician who, explains Heller, was “a total gym rat” named Vinh Cao. So they decided to put him to work. The team installed a pull up bar in the lab, and after completing a couple of sets, Cao would use what the team had nicknamed, “the glove.” After six weeks, Cao had improved, but the increase was predictable, with regular leaps in ability that you’d expect with regular workouts.
When using the glove between sets, Cao was able to jump up to 618 pull-ups in one session.
But one day Cao jumped back onto the pull up bar after completing a pull-up and then cooling session. Cao was able to repeat his initial set. The performance gave the researchers a jolt. When he had started the trials, the technician had jumped from 100 pull-ups to 180. But in the following six weeks, when using the glove between sets, he was able to jump up to 618 pull-ups in one session.
Cutting exercise induced exhaustion means conditioning with drastically reduced limits. “Muscle fatigue is largely due to the rise in temperature in the muscle,” says Heller. “So we were eliminating the fatigue factor. It would be of great value to the military and endurance athletes.”
They’ve been tweaking the model since. The most recent iteration, which will be released in early 2013, uses a mitt made of firm plastic that has 60 degree water circulating through it.
Results have been encouraging. But it’s the leaps in understanding that give the glove arguably more staying power than the head bucket and cheese cloth curtain.