Device and method for monitoring body fluid and electrolyte disorders
First Claim
1. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
- a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said light emission optics emit radiation at a plurality of spectral wavelengths chosen to be preferentially absorbed by tissue water, non-heme proteins and lipids, where preferentially absorbed wavelengths are wavelengths whose absorption is substantially independent of the individual concentrations of non-heme proteins and lipids, and is substantially dependent on the sum of the individual concentrations of non-heme proteins and lipids.
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Accused Products
Abstract
A device and a method for measuring body fluid-related metrics using spectrophotometry to facilitate therapeutic interventions aimed at restoring body fluid balance. The specific body fluid-related metrics include the absolute volume fraction of water in the extravascular and intravascular tissue compartments, as well as the shifts of water between these two compartments. The absolute volume fraction of water is determined using algorithms where received radiation measured at two or more wavelengths are combined to form either a single ratio, a sum of ratios or ratio of ratios of the form log[R(λ1)/R(λ2)] in which the received radiation in the numerator depends primarily on the absorbance of water and the received radiation in the denominator depends primarily on the absorbance of water and the sum of the absorbances of non-heme proteins, lipids and water in tissue. The difference between the fraction of water in the intravascular fluid volume (“IFV”) and extravascular fluid volume (“EFV”) compartments are also determined using a differential method that takes advantage of the observation that pulsations caused by expansion of blood vessels in the skin as the heart beats produce changes in the received radiation at a particular wavelength that are proportional to the difference between the effective absorption of light in the blood and the surrounding tissue. This difference, integrated over time, provides a measure of the quantity of the fluid that shifts into and out of the capillaries. A mechanism for mechanically inducing a pulse is built into the device to improve the reliability of measurements of IFV−EFV under weak-pulse conditions.
265 Citations
61 Claims
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1. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
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a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said light emission optics emit radiation at a plurality of spectral wavelengths chosen to be preferentially absorbed by tissue water, non-heme proteins and lipids, where preferentially absorbed wavelengths are wavelengths whose absorption is substantially independent of the individual concentrations of non-heme proteins and lipids, and is substantially dependent on the sum of the individual concentrations of non-heme proteins and lipids. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
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a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said light emission optics emit radiation at a plurality of spectral wavelengths falling within the range of 1100 to 2300 nm and the separation between said light emission optics and said light detection optics falls within the range of 1 and 5 mm. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
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a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said body fluid-related metrics comprises tissue water fraction, and where said tissue water fraction, ƒ
w is determined such thatand where; calibration constants c0 and c1 are chosen empirically;
R(λ
1) is a received radiation at a first wavelength;
R(λ
2) is a received radiation at a second wavelength; and
R(λ
3) is a received radiation at a third wavelength.- View Dependent Claims (38, 39, 40, 41, 42)
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43. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
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a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said light emission optics emit radiation at a plurality of spectral wavelengths chosen to ensure that said computed body fluid-related metrics are substantially insensitive to scattering variations and such that the optical path lengths through said tissue location at said wavelengths are substantially equal. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A device for measuring body fluid-related metrics using optical spectrophotometry comprising:
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a probe housing configured to be placed proximal to a tissue location which is being monitored;
light emission optics connected to said housing and configured to direct radiation at said tissue location;
light detection optics connected to said housing and configured to receive radiation from said tissue location; and
a processing device configured to process radiation from said light emission optics and said light detection optics to compute said body fluid-related metrics, wherein said light emission optics emit radiation at a plurality of spectral wavelengths chosen to ensure that measured received radiation from said tissue location are insensitive to temperature variations, wherein said wavelengths are temperature isosbestic in the water absorption spectrum or the received radiation signals are combined in a way that substantially cancel temperature dependencies of said individual received radiation signals when computing tissue water fractions. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61)
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Specification