Overview
Multi-Use Near-Infrared Spectroscopy System for Spaceflight Health Applications
Principal Investigator:
Gary E. Strangman, Ph.D.
Organization:
Harvard - Massachusetts General Hospital
Technical Summary
While ultrasound has proved invaluable for a wide variety of medical assessments during spaceflight, it is largely blind to two important aspects of human physiology: blood oxygenation and blood volume. Near-infrared spectroscopy (NIRS), in contrast, is highly sensitive to blood oxygenation and volume, and hence has many medical uses, ranging from the gold standard of pulse oximetry, to tissue oxygenation and perfusion measurements, to imaging of brain function, hemorrhage or ischemia. NIRS could thus provide an excellent complement to ultrasound for spaceflight medical use. Importantly, a single NIRS system could support all of the above applications, while using non-ionizing near-infrared light, and remaining noninvasive, low power and highly portable. Currently, the only NIRS-type measurement available in flight is pulse oximetry. Existing NIRS-based instruments are either ill-suited to spaceflight (large, heavy and consume too much power), or are incapable of imaging.
The research project’s central objective is to develop and test a new NIRS system, NINscan M: a multi-use, wearable, and battery powered device with three distinct NIRS capabilities: (1) imaging of regional tissue oxygenation, perfusion and hemodynamics, including brain function; (2) point measurements of oxygenation suitable for muscle assessment; and, (3) pulse oximetry. These capabilities can fill key roles in spaceflight medical assessment, and could help address gaps in at least seven Human Research Roadmap risk categories: recognizing injured or ill crewmembers, muscle status monitoring, orthostatic intolerance assessment, detection or monitoring of behavioral or psychiatric conditions, effects of radiation on the central nervous system, sleep loss, and cardiac effects of spaceflight.
The NINscan M design will be an embedded microcontroller system based upon the laboratory’s series of prototype NIRS devices, which have been designed for mobile and long-duration monitoring. In addition to the three NIRS capabilities above, the system will also include the ability to record synchronized, auxiliary data streams for monitoring cardiac and skeletal muscle electrical activity, motion, force production, and temperature to further enhance its diagnostic value. The overall system design will be modular, such that the NIRS and auxiliary sensors can be flown and used singly or in combination, as indicated by medical operational requirements.
To minimize the data management burdens for astronauts, NINscan M will be designed to seamlessly integrate with the NSBRI-supported SmartMed platform for automatically detecting, consolidating, storing, communicating and displaying biomedical and environmental data. Once developed, the researchers will thoroughly characterize the NINscan M system, and perform human testing for: (1) sensitivity and specificity to changes in blood volume and oxygenation when imaging skin perfusion (shallow layers) and imaging brain function (deep tissue); (2) the ability to quantify muscle force production and oxygen extraction to assess muscle performance; and, (3) validity in making pulse oximetry measurements.
During development, the research team will work with the International Space Station Medical Project to ensure the resulting system is designed and developed within the constraints and requirements for spaceflight hardware and software. NINscan M will thus provide new capabilities, complementary to those currently available in-flight, which are important for medical assessments across a wide variety of spaceflight medical conditions.