Method and apparatus for non-invasively measuring hemodynamic parameters using parametrics
First Claim
1. A method of tonometrically measuring the pressure in the blood vessel of a living subject, comprising:
- providing a transducer adapted for determining the pressure applied to at least one surface thereof;
disposing said at least one surface of said transducer proximate to said blood vessel;
varying the level of compression applied to said blood vessel by said transducer over time;
determining the level of compression where a desired condition of the pulse pressure associated with said blood vessel exists based on the pressure determined by said transducer;
maintaining said transducer at or near said level of compression where said desired condition exists;
measuring at least one pressure value using said transducer during at least a portion of said act of maintaining; and
scaling said at least one pressure value based on at least the body mass index (BMI) of said subject to produce a corrected value, said corrected value being substantially representative of the actual pressure within said blood vessel.
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Accused Products
Abstract
An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises a method of measuring a hemodynamic parameter (e.g., arterial blood pressure) by applanating or compressing portions of tissue proximate to the blood vessel of concern until a desired condition is achieved, and then measuring the hemodynamic parameter. Such applanation effectively mitigates transfer and other losses created by the tissue proximate to the blood vessel, thereby facilitating accurate and robust tonometric measurement. An algorithm adapted to maintain optimal levels of applanation is also described. Methods and apparatus for scaling such hemodynamic parameter measurements based on subject physiology, and providing treatment to the subject based on the measured parameters, are also disclosed.
36 Citations
74 Claims
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1. A method of tonometrically measuring the pressure in the blood vessel of a living subject, comprising:
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providing a transducer adapted for determining the pressure applied to at least one surface thereof;
disposing said at least one surface of said transducer proximate to said blood vessel;
varying the level of compression applied to said blood vessel by said transducer over time;
determining the level of compression where a desired condition of the pulse pressure associated with said blood vessel exists based on the pressure determined by said transducer;
maintaining said transducer at or near said level of compression where said desired condition exists;
measuring at least one pressure value using said transducer during at least a portion of said act of maintaining; and
scaling said at least one pressure value based on at least the body mass index (BMI) of said subject to produce a corrected value, said corrected value being substantially representative of the actual pressure within said blood vessel.
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2. A method of measuring the pressure in the blood vessel of a living subject, comprising:
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providing at least one transducer adapted for determining the pressure applied to at least one surface thereof;
disposing said at least one surface of said at least one transducer proximate to said blood vessel;
varying the level of compression applied to said blood vessel by said at least one transducer over time;
determining the level of compression where a desired condition of the pulse pressure associated with said blood vessel exists based on the pressure determined by said at least one transducer;
maintaining said at least one transducer at or near said level of compression where said desired condition exists; and
measuring at least one pressure value using said transducer during at least a portion of said act of maintaining. - View Dependent Claims (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 method of biasing tissue during a blood pressure measurement, said tissue substantially overlying a blood vessel from which said pressure is determined, comprising:
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determining that value of a biasing force at which a first condition relating to said blood pressure occurs concurrently with a second condition; and
applying said determined first biasing force to at least a portion of said tissue. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A method scaling an unscaled blood pressure measurement derived from a living subject, comprising:
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determining a first physiologic parameter of said subject;
determining a second physiologic parameter of said subject;
forming a relationship between said first and second parameters; and
using said relationship to scale said unscaled blood pressure measurement. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method scaling an unscaled blood pressure measurement derived from a living subject, comprising:
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determining a first physiologic parameter of said subject, said first parameter being related to the body mass of said subject;
determining a second physiologic parameter of said subject, said second parameter being related to the location on said subject where said unscaled blood pressure measurement is obtained;
functionally relating said first and second parameters to produce a third parameter;
correlating said third parameter to a fourth parameter; and
scaling said unscaled blood pressure measurement using at least said fourth parameter. - View Dependent Claims (43)
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44. An apparatus for measuring the pressure within the blood vessel of a living subject comprising:
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a pressure transducer adapted to detect the pressure associated with said blood vessel and generate a signal relating thereto;
at least one storage device associated with said pressure transducer, said at least one storage device having scaling data stored therein;
at least one applanation assembly adapted to bias a portion of tissue proximate to said blood vessel;
a controller operatively coupled to said at least one applanation assembly and adapted to control the position thereof; and
a processor operatively connected to said transducer, at least one storage device, and said controller, said processor configured to generate an estimate of said blood pressure within said vessel based at least in part on said signal and said scaling data. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. An information storage device, comprising;
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a data storage medium;
a plurality of data stored on said medium, said plurality of data comprising a computer program adapted to run on a data processor, said data processor being operatively coupled to a controller which controls the position of a pressure transducer, said computer program, processor and controller being configured for determining the blood pressure of a living subject using the method comprising;
varying the level of compression applied to said blood vessel by at least one pressure transducer over time;
determining the level of compression where a desired condition of the pulse pressure associated with said blood vessel exists based on the pressure determined by said at least one transducer;
maintaining said at least one transducer at or near said level of compression where said desired condition exists; and
measuring at least one pressure value using said transducer during at least a portion of said act of maintaining.
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62. A method of positioning a pressure sensor with respect to a blood vessel, comprising:
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disposing said sensor proximate to said blood vessel such that at least some degree of pressure coupling between said blood vessel and said sensor exists;
moving said sensor in at least a first direction with respect to said blood vessel while obtaining a first pressure signal from said sensor;
moving said sensor in at least a second direction with respect to said blood vessel while obtaining at least a second pressure signal; and
analyzing said first and second signals to identify at least one relationship therebetween. - View Dependent Claims (63, 64, 65, 66, 67, 68, 69, 70)
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71. A method of qualifying physiologic pressure data, comprising:
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obtaining a plurality of pressure data from a subject;
obtaining a plurality of second data relating to at least one physiologic event within said subject; and
qualifying at least a portion of said pressure data based at least in part on said second data. - View Dependent Claims (72, 73, 74)
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Specification