Noninvasive method of measuring physiologic parameters
First Claim
1. A method of obtaining a physiological parameter of a body fluid compartment, comprising the steps of:
- a. applying a series of known pressure values to a body region containing a body fluid to deplete or replenish a fluid volume from the body region;
b. sensing the body region under pressure to derive a series of body fluid volume indications for a plurality of body fluid compartments in the body region under pressure;
c. referencing the body fluid volume indications of the plurality of body fluid compartments to the series of known pressure values; and
d. identifying a transitional relationship of the body fluid volume indication values referenced to the series of pressure values, thereby indicating the physiological parameter of the body fluid compartment.
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Abstract
The present invention provides means and methods for noninvasively identifying the blood pressure characteristics in each of the seven types of vessels in the circulatory system, including the central venous pressure (CVP) through a single monitoring system using fluid depletion plethysmography. Known pressure is applied to a body region in increasing amounts to force blood volume from the body region in step-wise fashion through each vessel type. Blood volume depletion for each vessel type is measured by the increasing electrical impedance of the body part during depletion and is plotted against the increasing pressure data. The resulting series of slope changes within the plotted curve reveals the blood pressure for each vessel type. The data obtained may further be used to determine vessel wall compliance/tension as well as standard measurements such as pulse and large artery systolic and diastolic pressure. Release of the applied pressure may then yield similar data by measuring blood volume replenishment against the decreasingly applied pressure during the same diagnostic operation. The method is not dependent on oscillometric or pulsatile measurement methods. The electrical leads of the impedance/volume sensor and the means for applying pressure to the body part are coextensive to ensure accurate indication of blood volume depletion and replenishment in the body region under pressure and may be incorporated into a single integrated structure.
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Citations
67 Claims
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1. A method of obtaining a physiological parameter of a body fluid compartment, comprising the steps of:
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a. applying a series of known pressure values to a body region containing a body fluid to deplete or replenish a fluid volume from the body region;
b. sensing the body region under pressure to derive a series of body fluid volume indications for a plurality of body fluid compartments in the body region under pressure;
c. referencing the body fluid volume indications of the plurality of body fluid compartments to the series of known pressure values; and
d. identifying a transitional relationship of the body fluid volume indication values referenced to the series of pressure values, thereby indicating the physiological parameter of the body fluid compartment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 30, 56)
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22. A method of obtaining a physiological parameter of a body fluid compartment, comprising the steps of:
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a) applying a series of known pressure values to a body region containing a body fluid to deplete or replenish a series of adjacent body fluid compartment fluid volumes from the body region;
b) sensing the body region under pressure to derive a series of body fluid volume indication values for the adjacent body fluid compartments of the body region under pressure;
c) referencing the body fluid volume indication values of the adjacent body fluid compartments to the series of known pressure values; and
d) identifying transition points at which a relationship of the body fluid volume indication values referenced to the series of pressure values changes, thereby indicating a body fluid physiological parameter. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
deriving a series of non-vascular fluid admittance values above the systolic pressure value, and graphing a second curve of the non-vascular fluid admittance values to the series of pressure values.
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29. The method of obtaining a vascular fluid profile of claim 28, further including the step of subtracting the second curve from the first curve of admittance values to obtain a true representation of only vascular admittance values.
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31. The method of obtaining a physiological parameter of claim 22, wherein the sensing is done by bioimpedance.
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32. The method of obtaining a physiological parameter of claim 22, further including the step of changing impedance values to admittance values.
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33. The method of obtaining a physiological parameter of claim 22, further including the step of using the transition points to determine diastolic and mean pressure and deriving a vessel wall tension value therefrom.
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34. The method of obtaining a physiological parameter of claim 22, wherein the step of referencing the body fluid volume indications to the series of known pressure values is done with a graphical representation.
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35. The method of obtaining a physiological parameter of claim 22, wherein the body region is substantially at heart level when the series of pressures is applied.
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36. The method of obtaining a physiological parameter of claim 22, wherein the body fluid indication values are referenced to the known pressure values when the pressure is increasing.
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37. The method of obtaining a physiological parameter of claim 22, wherein the body fluid indication values are referenced to the known pressure values when the pressure is decreasing.
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38. The method of obtaining a physiological parameter of claim 22, wherein the body fluid indication values are referenced to the known pressure values when the pressure is increasing and when the pressure is decreasing.
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39. The method of obtaining a physiological parameter of claim 22, wherein the step of applying a series of pressures includes applying pressure above a mean pressure of a large artery.
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40. The method of obtaining a physiological parameter according to claim 39, wherein the body fluid indication values are fluid volume values and further including the step of graphing a first curve of fluid volume values to pressure values.
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41. The method of obtaining a physiological parameter according to claim 40, further comprising the steps of:
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deriving a series of non-vascular fluid volume values above the mean pressure value, and graphing a second curve of the non-vascular fluid volume values to the series of pressure values.
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42. The method of obtaining a vascular fluid profile of claim 41, further including the step of subtracting the second curve from the first curve of fluid volume values to obtain a true representation of only vascular fluid volume values.
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43. Apparatus for obtaining a physiological parameter, comprising:
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a. a pressure applicator for application of a series of pressures to a body region containing a body fluid so as to deplete a series of fluid volumes from a plurality of body fluid compartments in the body region, the pressure applicator including means for applying the pressures at a known value;
b. a volume indicator for deriving body fluid volume indications of the plurality of body fluid compartments in the body region under pressure;
c. means for referencing the body fluid volume indications to the applied pressure value; and
d. means for identifying or displaying points at which a relationship of the body fluid volume indications referenced to the series of pressure values changes, thereby indicating state changes in a body fluid profile of the plurality of fluid compartments between two body fluid compartments having different fluid characteristics. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. Apparatus for obtaining a physiological parameter, comprising:
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a. a monitor unit comprising;
i) a system processor including;
a volume state monitor for receiving data related to fluid volumes from, and sending control signals to, a volume indicator, a pressure state monitor for receiving data related to a pressure applicator, a pressure control unit for sending control signals to a pressure applicator, a system timer for producing time values related to control of the monitor unit, a volume/pressure analyzer for referencing pressure data to volume data, and an input/output interface for permitting operator interaction with the apparatus, ii) a volume sensor for applying a current source to a bioimpedance sensor, and iii) a pressure generator for producing force to be applied to a pressure applicator;
b. a pressure applicator for application of a contiguous series of pressures to a body region containing a plurality of body fluid compartments so as to deplete a series of fluid volumes from the plurality of body fluid compartments, the pressure applicator including means for applying the pressures at a known value to a body region;
c. a bioimpedance sensor for deriving body fluid volume indications of the plurality of body fluid compartments under pressure; and
d. means for identifying or displaying points at which a relationship of the body fluid volume indications referenced to the contiguous series of pressures changes, thereby indicating state changes between two body fluid compartments having different fluid characteristics. - View Dependent Claims (57)
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58. A method of obtaining a physiological parameter of a body fluid compartment, comprising the steps of:
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a. applying a series of known pressure values to a body region containing a body fluid to deplete or replenish a fluid volume from the body region;
b. sensing the body region under pressure to derive a series of static body fluid volume indications for the body region under pressure;
c. referencing the static body fluid volume indications to the series of known pressure values; and
d. identifying a change in the relationship of the static body fluid volume indication values referenced to the series of pressure values, thereby indicating the physiological parameter in the body fluid compartment. - View Dependent Claims (59, 60)
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61. A method of obtaining a physiological parameter, comprising the steps of:
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a. applying a series of known pressure values to a body region containing a body fluid to deplete or replenish a series of fluid volumes from the body region;
b. placing a plethysmographic device at the body region under pressure to derive a series of body fluid volume indication values of the body region under pressure;
c. referencing the body fluid volume indication values to the series of known pressure values; and
d. identifying transition points at which a relationship of the body fluid volume indication values referenced to the series of known pressure values changes, thereby indicating state changes between two adjacent body fluid compartments having different fluid characteristics;
whereby at least one of the following physiological parameters is derived from the state changes;
a static fluid pressure selected from the group including;
a fluid pressure of the capillaries, a fluid pressure of the venuoles, a fluid pressure of the small veins, a fluid pressure of the large veins, and a fluid pressure of the arterioles; and
a fluid pressure of non-vascular fluid.- View Dependent Claims (62)
a static fluid pressure selected from the group including;
a fluid pressure of the small arteries, and a fluid pulsatile vessel blood pressure of the large arteries and wherein the physiological parameter of the large arteries is further selected from the group including;
a mean blood pressure of the large arteries, a systolic blood pressure of the large arteries, and a diastolic blood pressure of the large arteries.
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63. A method of obtaining a vascular fluid profile, comprising the steps of:
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a. applying a series of known pressure values to a body region at or near a heart level of the body, to deplete or replenish a series of vascular fluid volumes from vascular fluid compartments in the body region;
b. placing a bioimpedance sensor on the body region under pressure to derive a series of impedance or admittance values of the body region under pressure;
c. graphing a first curve of the impedance or admittance values to the series of pressure values; and
d. identifying transition points in the first curve thereby indicating state changes in a vascular fluid profile between two vascular fluid compartments having different characteristic vascular fluid pressures;
whereby at least one of the following physiological parameters are derived from the vascular fluid profile;
vessel compliance;
central venous pressure;
a static fluid pressure selected from the group including;
a fluid pressure of the capillaries, a fluid pressure of the venuoles, a fluid pressure of the small veins, a fluid pressure of the large veins, and a fluid pressure of the arterioles;
a fluid pressure selected from the group including;
a fluid pressure of the small arteries, and a fluid pulsatile vessel blood pressure of the large arteries and wherein the physiological parameter of the large arteries is further selected from the group including;
a mean blood pressure of the large arteries, a systolic blood pressure of the large arteries, and a diastolic blood pressure of the large arteries; and
a blood volume of the large arteries. - View Dependent Claims (64, 65, 66)
deriving a series of non-vascular fluid admittance values above a highest vascular pressure value, and graphing a second curve of the non-vascular fluid values to the series of pressure values.
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66. The method of obtaining a vascular fluid profile of claim 65, further including the step of subtracting the second curve from the first curve of admittance values to obtain a true representation of only vascular admittance values.
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67. A method of obtaining a physiological parameter of a body fluid compartment, comprising the steps of:
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a. applying a contiguous series of known pressure values to a body region containing a body fluid to deplete or replenish a series of fluid volumes from adjacent body fluid compartments of the body region;
b. sensing the body region under pressure to derive a series of body fluid compartment volume indication values as changed by the pressure applied to or removed from the body region under pressure;
c. referencing the series of body fluid compartment volume indication values to the series of known pressure values; and
d. identifying a change in the relationship of the series of body fluid compartment volume indication values referenced to the contiguous series of pressure values, thereby indicating the physiological parameter in the body fluid compartment.
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Specification