South Pole Slumber

If you think getting a good night’s sleep at home is hard, try catching 40 winks at the South Pole! It’s not such an easy task, says Mayo College of Medicine Professor Dr. Bruce D. Johnson.

According to Johnson, sleepers at the South Pole report an oxygen saturation of 79 percent at rest — about 20 percent lower than “normal” at-rest saturation readings. In short, Johnson says, slumber at the South Pole is physiologically like sleeping at an altitude of 16,000 feet, which is precisely why he and his research team recently made their second trek to Antarctica to study altitude illnesses with the VivoMetrics LifeShirt in tow.

Johnson and his crew used the LifeShirt garment, which contains cardiopulmonary and movement sensors, to provide and record valuable information from volunteer sleepers at the South Pole. The volunteers’ vitals are monitored during sleep at sea level using the LifeShirt, and then compared via LifeShirt readings to sleep at the Pole.

“At altitude, we tend to have many pauses or apneas in a very consistent pattern that can go on for much of the night. Every time you have an apnea, your oxygen drops lower. These are the things we are looking at, and these are the details that LifeShirt helps us monitor,” Johnson said.

A PhD with a background in respiratory physiology and cardiovascular diseases, Johnson has long harbored an interest in human environmental physiology — “how the systems of the body work together and adapt to environmental conditions.” His experiences in the field under his mentor, respiratory scientist Jerome Dempsy, lead Johnson to LifeShirt.

“We’ve been using LifeShirts for years,” Johnson said. “Since we do field work, and we’re trying to find ways to collect data, it was one of the few systems available that allowed us to monitor breathing, heart rate, oxygen saturation and other variables in ambulatory people,” he said.

In the years since its inception, LifeShirt has often been used to monitor the conditions of people in extreme situations, including racecar drivers and firemen. Today, LifeShirts are even being used by the Philadelphia Flyers hockey team.

Alex Derchak, principal scientist behind the LifeShirt, said applications for the monitoring technology are endless, especially within the home care industry.

“[Home care] is definitely the direction that the technology is going, but there is a lot of work to be done between here and there,” Derchak said. “It starts as a laboratory device and is tested by fire in the field, then it becomes smaller and lighter and is eventually introduced into the home care market. We’re definitely on that path.”

According to Derchak, adapting LifeShirt’s technology to the HME market would allow providers to monitor daily remote vital signs of their patients, which would assist in chronic disease management for patients with COPD, congestive heart failure or even diabetes.

“The work that Dr. Johnson is doing is really going to inform chronic disease management practices in the future, and a device like LifeShirt makes it a real possibility,” Derchak said.

Johnson has also tapped in to the many applications for LifeShirt. In addition to his studies in the Antarctic, Johnson said he uses the VivoMetrics device in his domestic studies in the Mayo College’s Colorado High Altitude Tent.

Johnson’s LifeShirt readings are part of a three-year study on altitude illness funded by the National Science Foundation. Currently in its second year, the goal of the study, according to Johnson, is to pinpoint the “base line characteristics” that contribute to altitude illness — age, gender, activity levels, sleep history, body habitus — in an effort to stem the frequency of the illness. Johnson said the data he and his researchers gather will also be beneficial in treating other diseases including lung disease and heart failure, which is the leading cause of hospitalizations in people over the age of 65.

Johnson said the sleep study has collected data from about 200 volunteers, and of those, about 70 participated in the LifeShirt segment. Johnson said he hopes to make one more research trip to Antarctica before presenting the study’s findings.