U.S. patent application number 13/738843 was filed with the patent office on 2013-05-16 for method and apparatus for estimating water reserves.
This patent application is currently assigned to COVIDIEN LP. The applicant listed for this patent is Covidien LP. Invention is credited to Clark R. Baker, JR..
Application Number | 20130123588 13/738843 |
Document ID | / |
Family ID | 39535659 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130123588 |
Kind Code |
A1 |
Baker, JR.; Clark R. |
May 16, 2013 |
Method and Apparatus for Estimating Water Reserves
Abstract
A system and method are provided for a water reserve index. The
method includes determining a lean water fraction of tissue for at
least one tissue site and determining skin thickness for the at
least one tissue site. The lean water fraction and skin thickness
are combined to produce a water reserve estimate.
Inventors: |
Baker, JR.; Clark R.;
(Newman, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covidien LP; |
Boulder |
CO |
US |
|
|
Assignee: |
COVIDIEN LP
Boulder
CO
|
Family ID: |
39535659 |
Appl. No.: |
13/738843 |
Filed: |
January 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11716778 |
Mar 9, 2007 |
8357090 |
|
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13738843 |
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Current U.S.
Class: |
600/306 |
Current CPC
Class: |
A61B 5/1075 20130101;
A61B 8/0858 20130101; A61B 5/443 20130101; A61B 5/4869 20130101;
A61B 5/441 20130101; A61B 5/0075 20130101; A61B 5/0059
20130101 |
Class at
Publication: |
600/306 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1. A method for determining a water reserve index comprising:
determining a lean water fraction of tissue for at least one tissue
site; determining skin thickness for the at least one tissue site;
and using the lean water fraction and skin thickness to produce a
water reserve estimate.
2. The method of claim 1, wherein the lean water fraction is
determined spectroscopically.
3. The method of claim 2, wherein the lean water fraction is
determined based on spectral absorption bandwidth.
4. The method of claim 1, wherein the skin thickness is determined
spectroscopically.
5. The method of claim 1, wherein the skin thickness is determined
ultrasonically.
6. The method of claim 1, wherein the skin thickness is determined
mechanically.
7. The method of claim 6, comprising using calipers.
8. The method of claim 4, wherein the skin thickness is determined
by spectroscopically determining the amplitude of spectral features
corresponding to a subcutaneous fat layer relative to spectral
features corresponding to water and protein.
9. The method of claim 1, wherein determining the water reserve
index comprises adjusting the water reserve index for elevation
differences between the heart and the at least one skin site.
10. The method of claim 9, wherein the relative elevation of the
skin site is averaged over a period representative of the
equilibrium time of the interstitial compartment.
11. A device for determining a water reserve index comprising: a
processing device configured to receive a signal from a sensor
representative of detected light, the detected light being emitted
light that has been scattered or absorbed by constituents of an
individual's skin, to calculate a lean water fraction based on the
received signal, and to combine the lean water fraction with a skin
thickness value to determine a water reserve index.
12. The device of claim 11, wherein the processing device is
configured to compute the skin thickness value based on the
received signal.
13. The device of claim 12, wherein the processing device is
configured to compute the skin thickness value based on the
received signal by determining an amplitude of spectral features
corresponding to a subcutaneous fat layer relative to spectral
features corresponding to water and protein
14. The device of claim 11, wherein combining the lean water
fraction with the skin thickness value comprises multiplying the
lean water fraction with the skin thickness value.
15. The device of claim 11, wherein the processing device is
configured to send a signal to a display of the device to display
the determined water reserve index.
16. An apparatus for determining a water reserve index comprising:
means for determining a lean water fraction of tissue for at least
one tissue site; means for determining skin thickness for the at
least one tissue site; and means for using the lean water fraction
and skin thickness to produce a water reserve estimate.
17. The apparatus of claim 16, wherein the means for determining
the water reserve index comprises a means for adjusting the water
reserve index for elevation differences between the heart and the
at least one skin site.
18. The apparatus of claim 17, wherein the relative elevation of
the skin site is averaged over a period representative of the
equilibrium time of the interstitial compartment.
19. The apparatus of claim 16, wherein the means for determining
the lean water fraction determines the lean water fraction
spectroscopically based on spectral absorption bandwidth.
20. The apparatus of claim 16, wherein the means for determining
the skin thickness value determines the skin thickness value
spectroscopically by determining an amplitude of spectral features
corresponding to a subcutaneous fat layer relative to spectral
features corresponding to water and protein.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/716,778, entitled "Method and Apparatus for Estimating
Water Reserves", filed Mar. 9, 2007, which is herein incorporated
by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to determining
physiological parameters and, more particularly, to estimating
water reserves.
BACKGROUND
[0003] This section is intended to introduce the reader to various
aspects of art that may be related to various aspects of the
present invention, which are described and/or claimed below. This
discussion is believed to be helpful in providing the reader with
background information to facilitate a better understanding of the
various aspects of the present invention. Accordingly, it should be
understood that these statements are to be read in this light, and
not as admissions of prior art.
[0004] In healthy individuals, homeostatic control mechanisms
ensure that a balance between fluid gain and fluid loss is
maintained and, therefore, maintaining fluid balance is typically
not an issue requiring attention. In ill individuals, however, the
maintenance of body fluid balance may be cause for great concern.
Dehydration or edema may occur if fluid balance is not properly
maintained. For example, dehydration of infants and children
suffering from diarrhea and/or vomiting can be life threatening if
not recognized and treated promptly. Additionally, many elderly
people have an increased risk of dehydration because they have
thin, fragile skin, which is a major reservoir of water for the
body.
SUMMARY
[0005] Certain aspects commensurate in scope with the originally
claimed invention are set forth below. It should be understood that
these aspects are presented merely to provide the reader with a
brief summary of certain forms the invention might take and that
these aspects are not intended to limit the scope of the invention.
Indeed, the invention may encompass a variety of aspects that may
not be set forth below.
[0006] In accordance with one aspect of the present invention,
there is provided a method for determining a water reserve index.
The method comprises determining a lean water fraction of tissue
and skin thickness for at least one site. The method also comprises
combining the lean water fraction and skin thickness to produce a
water reserve estimate.
[0007] In accordance with another aspect of the present invention,
there is provided a method for determining skin thickness. The
method comprises emitting electromagnetic radiation from a sensor
at an individual's skin and detecting the emitted electromagnetic
radiation after it has been scattered and absorbed by constituents
of the skin. The method also comprises determining the prominence
of spectral features corresponding to a subcutaneous fat layer,
wherein the prominence of spectral features indicates skin
thickness.
[0008] In accordance with yet another aspect of the present
invention, there is provided a system for determining a water
reserve index. The system includes a sensor comprising an emitter
configured to emit near-infrared light and a detector configured to
detect the emitted light and generate a signal representative of
the detected light. The system also including a monitor
communicatively coupled to the sensor and configured to receive the
generated signal. The monitor comprising a microprocessor
configured to calculate a lean water fraction based on the received
signal. The microprocessor further configured to combine the lean
water fraction with a skin thickness value to determine a water
reserve index. The monitor also comprising a display configured to
display the determined water reserve index to the user.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Certain exemplary embodiments are described in the following
detailed description and in reference to the drawings in which:
[0010] FIG. 1 illustrates a system for determining hydration in
accordance with an exemplary embodiment of the present
invention;
[0011] FIG. 2 illustrates a cross-sectional view of a sensor of the
system of FIG. 1 in accordance with an exemplary embodiment of the
present invention;
[0012] FIG. 3 illustrates a plot of euhydrated skin showing lipid
(fat) peaks at 1210 nm, 1725 nm, and 1765 nm;
[0013] FIG. 4 illustrates a plot of the euhydrated skin of FIG. 3
and plot showing reduction of the lipid peaks as an effect of
overhydration; and
[0014] FIG. 5 illustrates a technique for determining a hydration
index based on an estimate of the fraction of water in the skin and
skin thickness, in accordance with an exemplary embodiment of the
present invention.
DETAILED DESCRIPTION
[0015] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, not all features of an actual
implementation are described in the specification. It should be
appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0016] In accordance with the present technique, a system and
method are disclosed for estimating an individual's water reserves.
The technique includes determining a water reserve index based on
two factors: an estimate of the lean water fraction and the
thickness of the skin. The two factors may be used to produce a
water reserve index indicative of the amount of water reserves an
individual has available in the form of skin cell hydration. The
water reserve index may be measured relative to a level of skin
hydration clinically determined to be indicative of a dehydrated
state. Accordingly, the water reserve index may be indicative of an
amount of water above or below the dehydrated level.
[0017] Turning to FIG. 1, a system for non-invasively determining
physiological parameters is illustrated in accordance with an
exemplary embodiment of the present invention and is generally
designated by the reference numeral 10. The system 10 includes a
sensor 12 coupled with a monitor 14 via a cable 16. The system may
also include an input device, such as a keyboard 18 and an output
device, such as a display 20. The keyboard 18 may be configured to
allow a user, such as a clinician, to enter various parameters or
baseline hydration levels, as will be discussed below. The display
20 may be configured to display a lean water fraction, a skin
thickness, and/or a water reserve index measurement among other
things.
[0018] The sensor 12 is configured to contact an individual's skin
22 on a site where measurements are to be taken. A cross sectional
view of the sensor 12 is shown in FIG. 2 to illustrate that the
sensor 12 may include at least one emitter 24 and at least one
detector 26 component parts of the sensor 12. As can be seen, the
emitter 24 and the detector 26 are located on a substantially flat
surface of the sensor 12 so that they may optically couple with an
individual's skin 22.
[0019] The emitter 24 may include one or more electromagnetic
radiation sources or light sources, such as light emitting diodes
(LEDs), an array of LEDs, a white light source, a tunable laser, or
any other source that transmits electromagnetic radiation within a
region of the electromagnetic spectrum useful for the determination
of physiological parameters. Specifically, the near-infrared region
(NIR) of the electromagnetic spectrum is particularly useful in
measuring relative concentrations of tissue constituents for the
determination of skin thickness and water content. In the 1100-1400
nm and 1600-1900 nm regions, water, protein and fat have
distinctive absorbance spectra that can be used to determine their
relative concentrations. As such, the emitter 24 in this embodiment
operates in the NIR range.
[0020] The detector 26 may be a photosensitive diode,
photosensitive transistor or other means for detecting
electromagnetic radiation within the range of the electromagnetic
spectrum of the emitter 24. The detector 26 is configured to detect
electromagnetic radiation originating from the emitter 24 after it
has passed through a patient's skin and been absorbed and/or
scattered by the constituent parts of the tissue.
[0021] The sensor 12 may be a reflection-type sensor, as
illustrated in FIG. 1, where the emitter 24 and detector 26 are
substantially in the same plane and spaced 1-5 mm apart, or a
transmission-type sensor, where the emitter 24 and detector 26 are
placed on substantially opposite sides of the tissue site. More
specifically, because the detector 26 is in the same plane as the
emitter 24 in the reflectance-type sensor, the detector 26 detects
light that has been reflected and/or scattered by the tissue. In
contrast, in a transmission-type sensor, the sensor's emitter and
detector lie in parallel planes on opposing sides of the tissue.
The optical path of the light originating from an emitter in a
transmission-type sensor is substantially in-line with an imaginary
axis connecting the emitter and the detector, and the detector
detects light that has been transmitted through the tissue along
the optical path.
[0022] Methods for estimating the lean water fraction in the skin
by near-infrared (NIR) spectrophotometry have been described in the
art and a number of theoretical scattering models have been applied
to tissue spectra in order to allow for the estimation of
constituent spectra. In particular, methods for measuring the lean
water fraction in tissue by NIR spectroscopy are described in U.S.
Pat. No. 6,591,122, U.S. Pub. No. 2003-0220548, U.S. Pub. No.
2004-0230106, U.S. Pub. No. 2005-0203357, U.S. Pat. App. No.
60/857,045, U.S. patent application Ser. No. 11/283,506, and U.S.
patent application Ser. No. 11/282,947, all of which are
incorporated herein by reference. In addition to the methods and
algorithms disclosed by the above mentioned patents and
applications, the spectral absorption bandwidth may be used to
estimate tissue constituent concentration and, more specifically,
water content of tissue, as disclosed in U.S. patent application
Ser. No. 11/528,154 which is also incorporated by reference.
[0023] The lean water fraction may generally be described as a
ratio of the water-to-protein in the tissue. Protein content may be
challenging to estimate because it comprises a class of thousands
of different molecules and many of the absorption peaks in the
protein spectrum are close to absorption peaks for fat. Water,
however, is generally the most prominent absorber in the NIR
spectrum. The absorption spectrum of water varies primarily with
the degree of hydrogen bonding between water and/or other polar
molecules, but most of this variation may be correlated with
temperature, which can be easily measured. The lean water fraction
may be correlated to a whole body hydration index or a local
hydration index.
[0024] In addition to an estimate of the lean water fraction in the
skin, as determined by the techniques in the incorporated
references for example, skin thickness may be used to estimate an
individual's water reserves and provide an index of the
individual's water reserves. As mentioned above, the skin may be a
major reservoir of water for the body. Generally, thicker skin
indicates the body has the capacity for storing more water and
thinner skin indicates the body has the capacity for storing less
water. As will be discussed in greater detail below, the skin
thickness may be used in conjunction with other methods for
determining hydration levels to estimate an individual's water
reserves.
[0025] Skin thickness may be measured by any of a number of
suitable techniques. For example, skin thickness may be measured by
spectroscopic means. A subcutaneous fat layer can be seen in
spectroscopic analysis of the human skin and mammalian skin, in
general. As illustrated in FIG. 3, experiments on euhydrated
porcine models show that the subcutaneous fat layer is readily
visible as lipid peaks at 1210 nm, 1725 nm, and 1765 nm. Sensors
configured to have 2.5 mm emitter-detector spacing were using to
produce the plots of FIGS. 3 and 4. It is estimated that the mean
photon penetration depth is around 1 mm with the 2.5 mm spacing.
Based on an evaluation of the plots, fat accounts for about 20-30
percent of the total tissue traversed by near-infrared photons in
piglets. It can be estimated that fat will account for a somewhat
lower percentage in adult humans.
[0026] Turning to FIG. 4, a plot of overhydrated porcine models
superimposed on the plot of the euhydrated porcine model of FIG. 3
is illustrated. As can be seen, the lipid peaks are less prominent
when the porcine models are in an overhydrated state. The relative
amplitude of the lipid peaks is lessened because the skin thickness
has increased as more water is stored in the skin in the
overhydrated state. The thicker skin results in less of the
near-infrared photons traversing the subcutaneous fat layer before
being detected. Although not shown in the figures, removal of fluid
from the piglets via ultrafiltration causes the fat peaks to become
more prominent due to the skin becoming thinner and more of the
photons reaching the subcutaneous fat layer. The thickness of the
skin, therefore, may be determined based on the amplitude of the
fat spectrum relative to the other constituents, protein and water,
present in the spectrum.
[0027] Specifically, the relative amplitude of the lipid features
relative to the rest of the spectrum may be indicative of the water
content of the skin. The relative amplitude may be determined by
analysis of the full spectrum of a tissue site in comparison to the
spectra of pure analytes (water, protein, and fat), as discussed in
detail in U.S. Ser. No. 11/716,482, filed Mar. 9, 2007 and titled
"Method and Apparatus for Spectroscopic Tissue Analyte
Measurement," which is incorporated herein by reference.
Alternatively, the relative amplitude of the fat features may be
determined using a relatively small number of selected wavelengths,
one of which should be absorbed more strongly by fat than water. It
has been determined that at least two wavelengths are needed for a
reasonable determination of tissue water, so at least three
wavelengths may be required to also incorporate an empirical
determination of fat relative to water and protein.
[0028] Because humans also have a subcutaneous fat layer, the
relative amplitude of the lipid features in the NIR skin spectra is
useful to determine skin thickness in humans. Although the skin
thickness will vary between sites and between individuals, it may
be assumed that the subcutaneous fat store is sufficiently thick at
most sites to assure that NIR photons will not penetrate below it,
and that virtually all the water and protein traversed by the NIR
photons will be above the subcutaneous layer. For example, for a
healthy adult male weighing 70 kg and having a total surface area
of about 18000 cm.sup.2, a subcutaneous fat store of 10% of body
weight would have a volume of 7800 cm.sup.3 and, therefore, average
about 4.3 mm thick. Although the subcutaneous fat layer accounts
for a lower percentage of the total tissue traversed by the
near-infrared photons in humans than in pigs, a correlation between
the relative amplitude of the lipid features and skin thickness may
be made. As stated above, thinner skin may be indicated by a
greater amplitude of the lipid features, including peaks, relative
to the other constituents and thicker skin may be indicated by
lesser relative amplitude of the lipid features. A correlation
factor for correlation between the relative amplitude of lipid
features and skin thickness may be empirically determined for
specific sites. For example, site specific empirical testing may be
performed comparing the relative amplitude of the fat features with
water and protein to determine the correlation between the relative
amplitude and the skin thickness.
[0029] Multiple alternative means for estimating skin thickness are
known and may be implemented. For example, Skin thickness may be
estimated using high frequency (near 15-20 MHz) ultrasound signals
or Harpenden skinfold calipers. The skin thickness estimated by the
ultrasound technique may be manually or automatically entered into
the system 10, while a skinfold estimate may be manually entered.
Because the spectroscopic technique for determining skin thickness
is based on the amount of light that penetrates to the subcutaneous
fat layer and, in a transmission type sensor, all of the detected
light passes through all the tissue layers a transmission type
sensor is not adapted to make a skin thickness measurement.
Accordingly, one of the above mentioned, techniques for determining
skin thickness may be implemented when a transmission type sensor
is used.
[0030] Once the thickness of the skin is determined, it can be
correlated to a hydration level of the individual based on
empirically determined relationships between skin thickness and
hydration levels. As mentioned above, a water reserve index may be
determined based on the combination of two factors indicative of an
individual's hydration level. FIG. 5 is a flow chart illustrating a
technique 40 for analyzing these two factors to determine a water
reserve index. The technique 40 includes estimating a lean water
fraction value, as indicated at block 42. The lean water fraction
estimation may be performed spectroscopically by one of the above
mentioned techniques. For example, in accordance with an exemplary
embodiment, the system 10 of FIG. 1 may be configured to determine
a lean water fraction in accordance with known algorithms.
[0031] Additionally, the technique 40 also includes estimating a
skin thickness value, as indicated at block 44. The skin thickness
value may be performed in accordance with any one of the above
mentioned methods, including spectroscopic, ultrasound, or caliper
means. If, for example, the skin thickness is determined
spectroscopically, the system 10 may be configured to determine
both the lean water fraction value and the skin thickness value in
addition to determining the water reserve index, as will be
explained below. As described above, if the skin thickness
measurement is made spectroscopically, at least three discrete
wavelengths may be used, including one at which electromagnetic
radiation is absorbed more by fat than by water.
[0032] Once the two factors, the lean water fraction value and the
skin thickness value, are determined, the system 10 may combine the
values to obtain a water reserve index, as indicated at block 46.
For example, a water reserve index might be computed using an
equation of the form:
Water Reserve=(Lean Water Fraction-offset)*Skin_Thickness,
where the offset takes into account that some of the water in the
skin is tightly bound to proteins inside or outside of cells and
cannot readily move around the body. The computed water reserve
index is indicative of the amount of water in the body and may be
correlated to a clinically determined dehydrated condition.
Specifically, a water reserve index value may be empirically
determined for a clinically dehydrated state. The computed water
reserve index may use the clinically determined dehydrated water
reserve index value as a baseline for determining the amount of
water reserves above the dehydrated state.
[0033] As mentioned above, skin thickness and hydration values may
vary based on the site at which the sensor 12 is taking
measurements. To the extent that the normal skin thickness or
hydration varies between sites, the proposed hydration index may be
site specific. Several means of indicating a skin site are known in
the art and may include incorporating an electronic ID chip into
sensor design for a specific site. One technique is disclosed in
U.S. Ser. No. 11/716,264, filed Mar. 9, 2007 and titled "Method for
Identification of Sensor Site by Local Skin Spectrum Data," which
is incorporated herein by reference. Additionally, a particular
sensor may be designed for use on a particular site, such as the
forehead, for example, and it may contain an ID chip indicating
that it is taking measurements from that particular site. The
monitor 14 (FIG. 1) may also have a keyboard 18, or other input
device, through which a user may communicate location detail to the
monitor 14. Alternatively, the monitor 14 may provide a display 20
that allows the user to indicate the sensor 12 location. Further,
once the monitor 14 knows the location at which measurements are
being taken, the monitor 14 may calibrate itself accordingly to
increase the accuracy of the system 10. For example, the monitor 14
may be configured to select appropriate coefficients or constants
to be used in the algorithms to compensate for any location
specific variation in skin thickness and/or hydration. Appropriate
coefficients or constants associated with the determination of the
lean water fraction, skin thickness, and/or water reserve index may
be determined empirically based on clinical studies.
[0034] In an alternative embodiment, the monitor 14 may be
configured to allow a user, such as a clinician, to input baseline
hydration levels for a particular site or, via the keyboard 18.
Specifically, for example, a user may enter the clinically
determined dehydration values against which the computed water
reserve index can be compared to determine if a patient is in a
dehydrated or over hydrated state.
[0035] Additionally, it is further known that skin thickness
increases during the day at sites that typically remain lower than
the heart, such as the feet and ankles, as a result of
gravitational forces. The skin thickness measurement may,
therefore, be adjusted for the elevation of the sensor site
relative to the heart. Because the elevation dependent hydration
changes occur primarily in the interstitial compartment, the
elevation based adjustments may reflect the average elevation
differences from the heart over the approximate equilibration time
of the interstitial compartment, which may take tens of
minutes.
[0036] Several techniques that may be implemented for determining
the elevation, position and/or orientation of the sensor are
discussed in U.S. Pub. No. 20060253016, which is incorporated
herein by reference. Specifically, For example, means of
determining elevation changes relative to the heart might include
settings on the surgical table or hospital bed, a camera, a small
tube with fluid and a pressure sensor at one end. In addition, a
water probe location sensor may include one or more mechanical
linkages, such as, e.g., an arm with a joint, that attaches to a
probe. In these cases, the position and/or orientation of a probe
may be ascertained from the length of the arm, the angle of its
joint, and/or the position of the subject. Remote water probe
location sensors may also provide location information relative to
the subject's body, such as, e.g., where a sensor uses optical
and/or ultrasound emitters (e.g., on the probe, subject, and/or
hospital bed) and detectors (e.g., on the sensor). Alternatively, a
sensor may include a video camera and/or may use object recognition
image processing software to detect probe location and/or tissue
site position, orientation, and/or elevation. In yet another
example, a sensor may also receive signals from one or more small
piezoelectric vibratory gyroscopes located in a probe. These may be
the same types of gyroscopes that may be used in automobile
navigation systems and may allow detection of probe location
information. Other alternative techniques may be implemented and
the relative elevation of the sensor may be input to the monitor 14
via the keyboard 18 or the display 20.
[0037] Therefore, in computing the skin thickness, the monitor 14
may be configured to use particular coefficients or constants to
calibrate for site specific conditions as well as the elevation of
the sensor site relative to the heart. As described above, the site
specific information and the elevation information may be input
manually via the keyboard 18 or monitor 20. Alternatively, the
sensor 12 and monitor 14 may be configured to automatically
determine the elevation and site specific information.
[0038] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Indeed, the present techniques may not only be applied to
measurements of tissue hydration, but these techniques may also be
utilized for the measurement and/or analysis of other analytes.
[0039] The invention, therefore, is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the invention as defined by the following appended claims.
* * * * *