NIR monitor, unaffected by skin color or body fat, measures blood and tissue chemistry, metabolism
May 4, 2009--Researchers who have developed a noninvasive system for measuring tissue oxygen and pH with light say their invention will soon provide an alternative to needles for drawing blood and cumbersome equipment for determining metabolic rate. Development of the Venus prototype system's sensor and portable monitor were funded by the National Space Biomedical Research Institute (NSBRI) for use in space, but the device has everyday application to critically ill patients on Earth.
Placed directly on the skin, the four-inch by two-inch sensor uses near infrared (NIR) light to measure blood and tissue chemistry, metabolic rate (oxygen consumption), and other parameters. Blood in tiny vessels absorbs some of the light; the rest is reflected back to the sensor. The monitor analyzes the reflected light to determine metabolic rate, along with tissue oxygen and pH.
"Tissue and blood chemistry measurements can be used in medical care to assess patients with traumatic injuries and those at risk for cardiovascular collapse," said Dr. Babs Soller, who leads NSBRI's Smart Medical Systems and Technology team. "The measurement of metabolic rate will let astronauts know how quickly they are using up the oxygen in their life-support backpacks. If spacewalking astronauts run low on oxygen, the situation can become fatal."
One unique advantage of the near infrared device is that its measurements are not impacted by skin color or body fat. A noninvasive system also means a reduced risk of infection due to the lack of needle pricks.
Most of the system's development has occurred at the University of Massachusetts Medical School, where Soller is a professor of anesthesiology. She has worked closely with researchers at NASA Johnson Space Center in Houston to develop applications of the Venus system for space.
Former NASA astronaut and NSBRI User Panel Chairman Dr. Leroy Chiao said Soller's sensor system has very real benefits to people on the ground, especially to people in more rural areas. "Eventually, we expect first-responders would have these devices, which would provide feedback on the severity of a person's injury," Soller noted. "Data can be communicated directly to the hospital. Early access to this type of information may increase a victim's chances of survival." The system could also allow doctors to more efficiently monitor pediatric and intensive care patients. And athletes and physical therapy patients could benefit from its ability to determine the level of activity or exercise that is most beneficial to the individual.
Currently, Soller and her collaborators are working on several aspects to prepare the sensor for integration into spacesuits by reducing its size, increasing its accuracy in measuring metabolic rate, and developing the capability to run on batteries. These activities will also speed its application in helping to care for patients on Earth.
Find out more about the systemon the NSBRI site, which also includes information on other related projects.
Posted by Barbara G. Goode, [email protected], for BioOptics World.