I-Corps: Non-invasive Indirect Calorimetry using Transdermal Optical Sensors for Diagnosis and Treatment of Metabolic Diseases

Vanderbilt University, Nashville TN

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is the development of an optical sensor that measures calories burned in real time. The proposed technology addresses the need for physicians and dieticians to accurately map a patient’s metabolic rate, which may provide information to assist in guiding proper nutrition and significantly reduce costs in seriously ill patients. In addition, professional athletes and others in the fitness industry may utilize such a technology to further develop and track their performance, providing crucial information to their coaches and sports medicine personnel. Current standard technologies, such as the metabolic cart, are large, cost-prohibitive (>$50K), and require intensive training and personnel for operation. As an inexpensive alternative, clinicians rely on crude calculations and daily weight measurements to guide patient nutrition. These predictive equations are often not accurate and are non-inclusive, only applying to a subset of the population. Dietitians struggle with making estimates for a variety of patients, especially for premature infants and patients that are obese, undergoing liver transplant surgeries, or suffering from thyroid problems. Accurate metabolic information from the proposed device may significantly increase quality of care, reduce readmission rates, length of stay, and complications, and contribute to reduced costs and positive healthcare outcomes. This I-Corps project is based on the development of an optical sensor that evaluates peculiar gas analyte concentrations in the bloodstream to quantify the end-user’s metabolic rate. The goal is to implement the metabolism sensor as a wearable device to measure calorie output from a patient’s extremity (finger or ear). The metabolic rate sensor utilizes a transdermal or transcutaneous, non-invasive optical sensor that measures carbon dioxide (CO2) and oxygen (O2) levels in the blood. The ratio of incident light to collected light through tissue will provide the data needed to calculate the patient’s energy expenditure. As caloric fuel is burned in the body in the presence of O2, CO2 is produced before being exhaled. The sensor system employs low-cost light emitting diodes (LEDs) and photodiodes to measure the absorption and scattering of light at wavelengths specific to spectral markers of O2 and CO2. A proprietary algorithm adopted from the Weir equation estimates the number of calories burned in real time from continuous spectral measurement. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.