"It is not uncommon for injured soldiers in Iraq to be considered stable only to destabilize during transport (to Germany or the United States)," said Dr. Babs Soller of the University of Massachusetts Medical School. "Our device should help alert the caregiver of impending problems."

Developed by a team at the medical school, the device is a noninvasive sensor that caregivers could use to monitor oxygen and acid levels in muscles -- two known indicators of circulatory shock, a life-threatening condition that can occur after a patient loses a lot of blood. To detect shock, medical providers currently depend on the tried, true and inadequate markers of blood pressure and heart rate.

Soller is a spectroscopist, a scientist who studies the interaction between light and matter. Her device works by letting providers see how much oxygen a patient's tissues are getting because when blood flow to the muscle starts to decrease, it's an indicator that blood flow to the internal organs has also decreased.

"These changes happen earlier in shock than changes in the heart's ability to pump blood, which is what is measured with blood pressure and heart rate," said Soller,

Her device is based on the physiological fact that when oxygen supply decreases to a critical level, tissues start producing lactic acid. This acid production decreases the pH of the tissue, causing changes in tissue spectra, which Soller is adept at measuring. Since embarking on this project almost a decade ago, she and her colleagues have developed hardware, software and algorithms to calculate muscle pH, oxygen and hematocrit from near infrared spectra readings.

"These parameters together allow us to investigate how well oxygen is being delivered to tissue and if the availabl
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Contact: Karen Fleming-Michael
karen.fleming-michael@amedd.army.mil
301-619-7549
US Department of Defense Congressionally Directed Medical Research Programs
8-Jun-2006