NMR Based Device for Fluid Status Monitoring

Technology

This invention presents a novel method for non-invasively measuring physiological hydration state using nuclear magnetic resonance (NMR).  This technology utilizes 1H NMR, which measures the relaxivity of hydrogen in water.  Using NMR relaxivity component analysis and signal-processing methods, the amount of water in different tissue targets (e.g. intracellular, extracellular, interstitial, intravascular) can be determined.  This invention marks the first time applying NMR measurement to physiological hydration state.Vascularization varies in different anatomical locations and tissues of the body.  Signals from the vasculature can be detected by increasing the measurement volume and focusing on a region with reduced blood velocity where excited protons do not exit the field of measurement quickly. While not limited to a single tissue type, fingers contain dense capillary beds with relatively small amounts of muscle mass and are particularly convenient.  Simple spin-spin relaxation (T2) measurements of the fingers correlate with the hydration state of a human and appear to be equivalent to clinically accepted yet more invasive assessments.  This novel finger NMR unit is small (please refer to the figures), making it easy for a patient to comfortably place a finger in the field of measurement.    

Problem Addressed

 Hydration imbalance, either dehydration or over-hydration (hyponatremia), affects cognitive and physical abilities, negatively impacting cardiovascular function, compromising thermoregulation, and decreasing exercise performance.  Hydration imbalance is a critical, life-threatening problem that affects over 1.2 million people annually and represents over $44.7 billion in healthcare costs.  Dehydration is preventable and reversible, and hospitalization from fluid imbalance is preventable through monitoring and early intervention.  Though various tools and metrics exist to measure hydration state, such as body mass change, capillary refill time, plasma osmolality, and bioimpedance, there is no hydration assessment method that is fast, portable, accurate, non-invasive, and designed for outpatient settings.  

Advantages

• Portable, inexpensive, easy, fast, and reliable hydration sensor
• Potential to greatly reduce hospital spending on hydration imbalance