In this proposed phase i sbir research effort, we will develop a technique for rapid, non-invasive determination of core temperature from measured parameters of respired air (temperature, humidity, and velocity). We will modify our existing respiration transducer (which measures temperature and velocity of respired air) to include infrared measurement of water vapor. We will then construct a laboratory test bed for partially simulating the human respiratory tract (only the thermal characteristics will be simulated). This test bed will permit control of "core" temperature and controlled variation of the temperature, humidity, and velocity of respired air. We will use the test bed to acquire data for development of a nonlinear model of core temperature as a function of respired air temperature, humidity, and velocity; preliminary results indicate that this will be possible. Finally, we will conduct measurements in a limited number of human subjects to compare predicted core temperature (from respiratory parameters) with actual core temperature (directly measured with both a rectal and esophageal temperature sensor). Successful demonstration of this approach will permit noninvasive, nonobtrusive core temperature measurement within a few breaths. In addition to use with combat casualties, this technique should also be useful in human workload studies.
