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Human Research Program

Noninvasive Biosensor Algorithms for Continuous Metabolic Rate Determination--SMS01302

Completed Technology Project

Project Introduction

Ed. note (November 2011): Principal Investigator (PI) changed affiliation around October 2010 from University of Massachusetts Medical School to Reflectance Medical Inc., at which time this new grant was issued by NSBRI (National Space Biomedical Research Institute). See grant NCC 9-58-SMS01301 for reports prior to FY2011.

NASA is designing new spacesuits to meet the needs of future space exploration. Real-time measurement of metabolic rate during astronaut activity is a key function of the biosensor suite which is planned for the new spacesuit. This project developed novel near infrared spectroscopic (NIRS) algorithms and sensors for real-time assessment of metabolic rate (measured as the rate of oxygen consumption, VO2). This capability was intended to be incorporated into a smart system advising astronauts on their use of consumables during extravehicular activity (EVA). The specific aims of this project include the development of algorithms to calculate VO2 from NIRS spectra and validation of the algorithms during exercise in ground-based protocols which simulate plasma volume reduction during spaceflight. An additional aim of this project is to support the EVA suit testing program by developing small, lightweight, and robust sensors which can be used within the spacesuit to evaluate metabolic cost of the suit itself, on individual muscles.

In the final year of this project we completed the development of an algorithm that determines VO2 during cycling using NIRS to determine muscle oxygen saturation (SmO2) data along with heart rate. We demonstrated acceptable performance during exercise on subjects in both a normovolemic and hypovolemic state. With synergistic funds from the US Army Medical Research Command we completed the development of a solid state sensor and software algorithms to support its ability to correct spectra for interferences related to skin pigment and fat. A prototype of this system was provided to NASA Johnson Space Center (JSC) and a study of blood flow restricted exercise was completed with the sensor. Two commercial-grade systems were sent to the NASA-JSC Cardiovascular Lab. This project has produced a wearable sensor that terrestrial doctors and their patients can use to track and optimize exercise in the management health and fitness, as well as during related applications in the care of critically ill patients.

A company, Reflectance Medical Inc., has been formed to commercialize the sensor. The company received clearance from the Food & Drug Administration (FDA) to sell the CareGuide Oximeter 1100, a hospital-based system to noninvasively and continuously determine SmO2. The company has submitted its second 510(k) application for the mobile CareGuide 2100 Oximeter, which is a battery powered SmO2 sensor that displays results on an Android tablet or the Sotera ViSi Mobile wrist worn vital sign monitor. The CareGuide 3100 development is complete. The 3100 updates the CareGuide 2100 software to calculate pHm and hematocrit (Hct) from the same spectra. The CareGuide 3100 is targeted for submission to the FDA by the end of 2012.

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This is a historic project that was completed before the creation of TechPort on October 1, 2012. Available data has been included. This record may contain less data than currently active projects.

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