| Grant/Contract No.: |
NCC 9-58-SMS01301 |
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| Performance Goal No.: |
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| Performance Goal Text: |
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| Task Description: |
NASA is planning a return to the moon in the next decade with extended human presence on the lunar surface for both scientific and commercial objectives. Significant astronaut activity will be conducted in a spacesuit or EVA (extravehicular activity) suit. The suit becomes the astronaut's personal habitat, supplying O2, removing CO2, and maintaining appropriate temperature. During lunar surface exploration, the astronauts must have continuous real-time feedback to assure that all consumables (O2, cooling water, power) last until they can return safely to their quarters. The consumption rate of these resources depends upon the metabolic rate of the astronaut during EVA tasks and the suit's ability to manage thermal loads. This project will develop novel algorithms for our existing near infrared spectroscopy (NIRS) platform for real-time assessment of metabolic rate (measured as the rate of oxygen consumption, VO2) and muscle temperature. This capability is intended to be incorporated into biosensors which will be part of a smart system to advise astronauts about their usage of consumables during lunar surface activities. The following specific aims were proposed: 1. Develop and validate algorithms to accurately calculate VO2 from NIR spectra collected from muscle; 2. Develop and validate algorithms to simultaneously calculate muscle temperature; 3. Support incorporation of the sensor algorithms into the EVA suit testing program, where practical. We have demonstrated the feasibility determining VO2 with the Fick equation and data that can be collected solely through a NIRS system. The accuracy of this technique is currently limited at high exercise intensities, primarily due to inaccuracies in our stroke volume estimate. We have initiated human studies that will allow us to improve our ability to estimate stroke volume and increase the accuracy of our VO2 calculation. The goal for this project is the demonstration of decreased VO2 as a result of deconditioning (bed rest).
With synergistic funds from the US Army Medical Research Command and an additional small grant from NSBRI we have designed and demonstrated a completely solid-state (non fiber based) sensor. This sensor runs off a small battery pack and a handheld computer. A sophisticated user interface performs automated system set-up and on-the-fly error checking to optimize data quality in the face of changing blood flow. After laboratory evaluation in the JSC Cardiovascular Lab, the system will be available for in-suit testing by the EVA Physiology project.
This project has produced a prototype 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. |
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| Research Impact/Earth Benefits: |
This work will have direct Earth-based application. The fitness and exercise applications we are developing can be used to assist in the training and evaluation of elite and recreational athletes. This direct application of interest to NASA for assessing fitness in space may be useful to assess success of physical therapy in rehabilitating patients with muscle injury or atrophy.
The sensor, which also is of tremendous interest to the Army, will have application in emergency response vehicles, emergency rooms, and hospitals. Pre-hospital applications include assessing the severity of shock and triaging multiple casualties, as well as providing a sensor for a smart medical system to guide resuscitation from hemorrhage. In the ICU we expect that this monitor will find application in helping provide early identification of patients with hemodynamic instability before they go into shock.
The miniaturization of the sensor and monitor, required for EVA suit placement, will result in a highly portable system for emergency medical use. If small and inexpensive enough, it could be used world-wide for screening of anemia associated with malnutrition. |
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| Task Progress: |
Our collaborators in the JSC Cardiovascular lab implemented a technique to determine stroke volume during exercise using ultrasound imaging. Data collection using this technique has been completed for 31 subjects.
Spectral data collection has been completed on 6 subjects, both pre- and post-bed rest. Additionally, spectral data collection has been completed on 5 subjects in the hypovolemia study. Data review and analysis is underway.
Initial data review indicated that we needed to gain a better understanding of the impact of fluid shifts on our NIRS measurements. We conducted a stand test to determine the effect of postural changes on our NIRS measurements, including a independent assessment of blood volume using regional bioimpedance measurements. We learned in this study that it takes 15min after a transition from standing to supine for the blood volume to normalize across all anatomical sites. We took advantage of this information in a study at UMass to investigate the sensor's ability to measure SmO2 on different muscles through various fat thicknesses. After 15min of supine rest to allow blood to normalize across the body we demonstrated on 6 subjects, that SmO2 measurements were equal, despite the choice of muscle used for the measurement (shoulder, calf, upper thigh, or lower thigh). This study included fat thickness that ranged from 5-19mm.
We have received synergistic funding from non-NASA sources to develop a solid state, low profile sensor that can be worn in a space suit for determining metabolic rate. During this year we completed development of the prototype and demonstrated that it was equivalent to our fiber optic model in the measurement of muscle oxygen saturation and pH. With additional NSBRI support we also developed the technology to run the sensor off a battery pack and augmented our system automation to include on-the-fly error checking and correction. The requirements for the additional automation features were the result of feedback from our NASA collaborators, based upon their previous experience using our original fiber optic system. In exercise studies we found that the optical signal can degrade during certain exercise periods. The new sensor is able to detect these problems and correct them within a few seconds, so no data is lost. |
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| Bibliography Type: |
Description: (Last Updated: 10/08/2009) |
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| Abstracts for Journals and Proceedings |
Jin C, Zou FM, Ellerby G, Scott P, Soller BR. "Accurate, in-vivo NIR measurement of muscle SO2 through fat." SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. In press, October 2009. , Oct-2009 |
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| Abstracts for Journals and Proceedings |
Everett ME, Lee SM C, Stroud L, Scott P, Hagan RD, Soller BR. "Time-to-fatigue and Intramuscular pH Measured via NIRS during Handgrip Exercise in Trained and Sedentary Individuals." 56th Annual Meeting of the American College of Sports Medicine, Seattle WA, May 27-30, 2009. Med Sci Sports Exerc, 2009 May;41(5):205-6. http://dx.doi.org/10.1249/01.MSS.0000355183.35616.4d then click LWW access , May-2009 |
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| Abstracts for Journals and Proceedings |
Lee SM C, Ellerby G, Stroud L, Soller BR. "Hydrogen ion threshold differs between the thigh and calf muscles during locomotion." Integrated Physiology Conference, Hilton Head, SC, September 24-27, 2008. Integrated Physiology Conference. In press, 2008. , Sep-2008 |
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| Abstracts for Journals and Proceedings |
Zou FM, Peshlov B, Ross RR, Ellerby G, Scott P, Yang Y, Soller BR. "Feasibility of analyte prediction in phantoms using a theoretical model of near-infrared spectra." SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. In press, October 2009. , Oct-2009 |
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| Papers from Meeting Proceedings |
Soller B, Coates J, Ellerby G, Scott P, Peshlov B, Zou F, Ryan K, Convertino V. "Spectroscopic sensor for trauma care." 60th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Chicago, IL, March 2009. Proceedings of the 60th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Chicago, IL, March 2009, in press, 2009. , Mar-2009 |
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| Abstracts for Journals and Proceedings |
Ellerby GE C, Lee SM C, Stroud L, Norcross J, Gernhardt M, Soller BR. "Near-infrared spectroscopic measurements of calf muscle during walking at simulated reduced gravity-preliminary results." 56th Annual Meeting of the American College of Sports Medicine, Seattle, WA., May 27-30, 2009. Med Sci Sports Exerc, 2009 May;41(5):58-9. http://dx.doi.org/10.1249/01.MSS.0000354741.74499.2d then click LWW access , May-2009 |
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| Patents |
Patent Application 12/172,942. Patent Application, July 2008. Jul-2008 Soller BR. "Physical Performance Monitoring and Monitors." |
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| Patents |
Not yet available. Patent, August 2009. Aug-2009 Soller BR, Coates JP, Yang Y, Jin C. "Spectroscopic Sensors." |
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| Patents |
US Patent 7,532,919. Patent, May 2009. May-2009 Soyemi O, Soller BR, Yang Y. "Measuring Tissue Oxygenation." |
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