Body Hydration Monitor
Body hydration level is critical in maintaining both physical and cognitive health. Body water weight loss—dehydration—impairs abilities and can lead to severe health problems, even death. Seemingly minimal dehydration can quickly lead to increased difficulty of physical work and the inability to focus on the task at hand. The Hydration Monitor (HM) was developed based on our previous studies on correlation of tissue molecular composition and acoustic properties [1-4] and was supported, in part, by the Phase I SBIR funding from the Department of Defense for assessment of body hydration status in soldiers during deployment and training. The method implemented in HM is based on the experimental fact that ultrasound velocity through the soft tissue is a linear function of the tissue water content. Because muscle provides the largest body reservoir for water, the assessment of water imbalance is conducted by measuring speed of ultrasound in muscle. A prototype of HM was extensively tested in animal tissues in vitro , and in human studies involving adult patients with lower limb edemas and athletes during acute dehydration and rehydration [6,7]. These studies fully confirmed feasibility and efficiency of the proposed approach.
Currently, there is no effective tool available to measure hydration status and distinguish those at risk. The reliability and validity of current hydration assessment methods and criteria such as thirst, skin turgor, blood pressure, pulse, urine output and specific gravity, MRI, dilution methods and bioimpedance, is limited, and the methods are inaccurate or expensive. HM could be used to monitor patients with a wide variety of clinical conditions resulting in changes in individual’s hydration level, including alterations in body fluids pre- and post-surgery, digestion problems, blood pressure, muscle cramps, and obesity. Dehydration is a frequent cause of morbidity and mortality in the elderly. Another important application of MHM is in neonatology since dehydration is a leading cause of infant morbidity and mortality worldwide. In the United States, dehydration, secondary to gastroenteritis, accounts for 10% of hospital admissions. The tissue hydration monitor developed by Artann [8, 9] may enable the identification and monitoring of hydration status and may have a significant long-term impact on the morbidity and mortality of at-risk population.
- Sarvazyan AP, Lyrchikov AG: Correlation of bulk elastic properties of soft biological tissues with content of water, protein and fat. Biomechanics in Medicine and Surgery, Riga 1986; 1:353-8.
- Sarvazyan AP, Lyrchikov AG, Gorelov SE: Dependence of ultrasonic velocity in rabbit liver on water content and structure of the tissue. Ultrasonics 1987; 25(4):244-7.
- Sarvazyan AP: Elastic properties of soft tissue. Handbook of Elastic Properties of Solids, Liquids and Gases 2001; III(5), eds Levy, Bass, Stern, Academic Press:107-27.
- Sarvazyan AP, Hill CR: Physical chemistry of the ultrasound-tissue interaction. Physical Principles of Medical Ultrasonics 2004; 7, eds Hill CR, Bamber JC, ter Haar GR, John Wiley & Sons:223-35.
- Sarvazyan AP, Tatarinov A, Sarvazyan N: Ultrasonic assessment of tissue hydration status. Ultrasonics 2005; 43(8):661-71.
- Topchyan A, Tatarinov A, Sarvazyan N, Sarvazyan AP: Ultrasound velocity in human muscle in vivo: Perspective for edema studies. Ultrasonics 2006; 44:259-64.
- Sarvazyan A, Tatarinov A, Sarvazyan N: Ultrasonic assessment of tissue hydration status with perspective for edema evaluation. Abstracts of the International Congress on Ultrasonics 2007 Apr; Vienna, Austria:65.
- Sarvazyan AP: Ultrasonic water content monitor and methods for monitoring tissue hydration. USA Pat 7,033,321 2006 Apr 25.
- Sarvazyan AP: Infant hydration monitor. USA Pat 7,291,109 2007 Nov 6.