Monitoring Health From Space: A New Use For GPS

Global Positioning Systems (GPS) have been found to be useful in a very different way than the standard navigation through seemingly illogical street grids. French researchers have recently used GPS to monitor the maximum walking distance (MWD) for people with peripheral artery disease (PAD), a condition that can cause severe pain during walking and can lead to an increased risk of heart attack and stroke.

PAD is characterized by clogged leg arteries, and when the clogged arteries are put under the strain of extended walking, excessive pain and discomfort often results. The disease effects more than eight million Americans, and makes the risk of cardiovascular disease far more likely.

GPS systems use “at least 24 medium earth orbit satellites that transmit precise microwave signals. This enables a GPS receiver to determine its location, speed, direction and time.” This is how the GPS knows a car’s location almost immediately, and can determine the appropriate directions to reach the desired location.

24 PAD patients. 18 men and 6 women, ranging from 39 to 79 years of age, were monitored by GPS as they walked in a public park to determine their MWD (the amount of walking time before extreme pain sets in). The system used was a “$450 commercially available GPS device.” When pain set in, patients were told to stop walking, and the distance in which they had walked was recorded by GPS.

The space-based GPS system was found in the study to be both more effective and less expensive than typical practices that measure similar limitations for people afflicted with PAD and most commonly rely on a treadmill, which can only be done practically in a lab setting. “We found that MWD obtained at a person’s usual pace is largely superior to the MWD measured on a treadmill” stated study author Dr. Pierre Abraham.

If the findings of the study are confirmed in future research, the use of GPS in monitoring patients may extend to other diseases “including heart failure and low oxygen levels induced by exercise in the blood of respiratory disease patients.” It’s perhaps strange to accept that a device in space can help monitor the inner workings of one’s body, but the technology may be an invaluable tool in keeping individuals with these conditions healthy and comfortable.

Source: Defeat Diabetes Foundation: Abraham, Pierre. et al. American Heart Association News Release. “Global positioning tracker may better gauge severity of peripheral artery disease.” February 1st 2008.