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.

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.

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.

SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. In press, October 2009. , Oct-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

Integrated Physiology Conference. In press, 2008. , Sep-2008

SPIE BiOS Conference, San Francisco, CA, January 23-28, 2010. In press, October 2009. , Oct-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

Proceedings of the 60th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Chicago, IL, March 2009, in press, 2009. , Mar-2009

We have entered into a new collaboration, supported by non-NASA funds, to develop a solid-state, low profile spectroscopic sensor which will have the potential to provide a prototype unit with appropriate characteristics to be used for ground testing within the EVA suit. Non-suit testing of this sensor at JSC is expected begin this calendar year.

The proposed biosensor system has built-in redundancy, through easy application to both limbs, and will provide system redundancy in the measurement of heart rate and temperature to further assure astronaut safely. The proposed technology is expected to result in wearable sensors 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.

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.

In the first year of this project our task was to improve the accuracy of our VO2 calculation. The two components of this are an improvement in the spectroscopic calculation of hematocrit (Hct) and venous oxygen saturation (SvO2), as well as an improved method for estimating stroke volume. We presented the results of our initial VO2 calculations to physiologists at the ACSM and AsMA meetings. Feedback we received indicated that the largest source of error was most likely in our estimate of stroke volume at high exercise intensities.

Over the last year we have developed a new calibration methodology that we expect will improve the accuracy of Hct and SvO2 measurement. This methodology is currently being tested in phantom materials and with previously collected data.

To improve our method of estimating stroke volume we have worked with the JSC Cardiovascular Laboratory to develop a method to determine stroke volume at each stage of the standard VO2max protocol. This technique was developed and tested on four pilot test subjects where we simultaneously measured VO2 and stroke volume with echocardiography. We received approval to add NIRS and echocardiography to the current bed rest campaign at UTMB and we have subsequently collected NIRS, echo and VO2 data from 5 bed rest subjects in their R-12 and R-7 testing. These subjects will be measured again at the end of their 90 day bed rest period. We also have been approved to add these additional measures to the cycle testing for the next planned bedrest campaign to imrpove the rate of our data collection.

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.

Med Sci Sports Exerc. 2008;40(5 Suppl):S426. , May-2008

Med Sci Sports Exerc. 2008;40(5 Suppl):S426. http://dx.doi.org/10.1249/01.mss.0000322816.61090.71 , then click LWW access. , May-2008

Integrated Physiology Conference. In press, 2008. , Sep-2008

Aviat Space Environ Med. 2008 Mar;79(3):294. , Mar-2008

Foundation for Anesthesia Education and Research (FAER) Symposium, Americal Society of Anesthesiologists Annual Meeting, October 2007. , Oct-2007

Proceedings of the 60th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Chicago, IL, March 2009, in press, November 2008. , Nov-2008

This project describes development of novel new algorithms for our 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 during lunar surface activities to ensure they do not run out of consumables prior to their return to the habitat.

The following specific aims are proposed:

1. Develop and validate algorithms to accurately calculate VO2 from NIRS spectra collected from muscle;

2. Develop and validate algorithms to simultaneously calculate muscle temperature; and

3. Support incorporation of the sensor algorithms into the EVA suit testing program.

The proposed biosensor system has built-in redundancy, through easy application to both limbs, and will provide system redundancy in the measurement of heart rate and temperature to further assure astronaut safety. The planned technology is expected to result in wearable sensors for terrestrial doctors and their patients to track and optimize exercise to help manage weight and fitness.