Method and apparatus for non-invasively measuring hemodynamic parameters using parametrics

• US 20040210143A1
• Filed: 05/03/2004
• Published: 10/21/2004
• Est. Priority Date: 02/05/2002
• Status: Active Grant

• Current Assignee: Zhejiang Shanshi Biological Medical Devices Company Limited
• Original Assignee: Gregory I. Voss, Stuart L. Gallant, William H. Markle
• Inventors: Markle, William H., Voss, Gregory I., Gallant, Stuart L.
• Granted Patent: US 7,867,170 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure

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.

Claims

1-74. -74. (Cancelled)

75. A method of measuring the pressure in the blood vessel of a living subject, comprising:

providing a transducer adapted to generate a signal relating to the pressure applied thereto;

disposing said transducer proximate to said blood vessel;

determining the level of compression where a desired condition of the pressure associated with said blood vessel exists based at least in part on the pressure signal generated by said transducer;

substantially maintaining 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 substantially maintaining; and

scaling said at least one pressure value based at least in part on a physiologic index of said subject to produce a corrected value, said corrected value being substantially representative of the actual pressure within said blood vessel.

76. The method of claim 75, further comprising varying the level of compression applied to said blood vessel over time at least once before or coincident with said act of determining.

77. The method of claim 75, wherein said physiologic index comprises body mass index (BMI).

78. The method of claim 75, wherein said act of substantially maintaining comprises substantially maintaining said level of compression using said transducer.

79. The method of claim 75, wherein said act of disposing further comprises disposing a bias element proximate to said transducer and said blood vessel, said bias element biasing at least a portion of the tissue proximate to said blood vessel so as to mitigate the effects thereof on said act of measuring.

80. The method of claim 75, wherein said physiologic index comprises body mass index (BMI), and said act of scaling comprises forming a ratio of said BMI to at least one physiologic parameter.

81. The method of claim 80, wherein said act of scaling further comprises correlating said ratio of said BMI and said at least one physiologic parameter to an error factor.

82. The method of claim 81, wherein said error factor comprises a scaling factor.

83. The method of claim 80, wherein said at least one physiologic parameter comprises pulse pressure (PP).

84. The method of claim 80, wherein said at least one physiologic parameter comprises wrist circumference (WC).

85. A method of measuring the blood pressure of a living subject, comprising:

measuring unscaled pressure values from a blood vessel of said subject; and

scaling said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) of said subject.

86. A method of measuring the blood pressure of a living subject, comprising:

measuring unscaled pressure values from a blood vessel of said subject; and

scaling said unscaled pressure values using a scaling factor, said scaling factor comprising a physiologic index of said subject, said physiologic index formed by relating at least two physiologic parameters associated with said subject.

87. The method of claim 86, wherein said at least two physiologic parameters comprise the height and weight of said subject.

88. A method of measuring the blood pressure of a living subject, comprising:

measuring unscaled pressure values from a blood vessel of said subject; and

scaling said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) and the pulse pressure (PP) of said subject.

89. A method of measuring the blood pressure of a living subject, comprising:

measuring unscaled pressure values from a blood vessel of said subject; and

scaling said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) and the wrist circumference (WC) of said subject.

90. Apparatus adapted to measure the blood pressure of a living subject, comprising:

first apparatus adapted to generate a signal relating to the pressure applied thereto; and

second apparatus configured to scale said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) of said subject.

91. The apparatus of claim 90, wherein said first apparatus comprises at least one tonometric pressure transducer adapted to be disposed proximate to a blood vessel.

92. The apparatus of claim 90, wherein said second apparatus comprises:

digital processing apparatus; and

a computer program operative to run on said digital processing apparatus, said computer program being adapted to receive data relating to said BMI and generate said scaling factor based at least in part thereon.

93. The apparatus of claim 90, further comprising a user interface operative to receive said data relating to said BMI from a user.

94. Apparatus adapted to measure the blood pressure of a living subject, comprising:

first apparatus adapted to generate a signal relating to the pressure applied thereto; and

second apparatus configured to scale said unscaled pressure values using a scaling factor, said scaling factor comprising a physiologic index of said subject, said physiologic index formed by relating at least two physiologic parameters associated with said subject.

95. The apparatus of claim 94, wherein said at least two physiologic parameters comprise the height and weight of said subject.

96. The apparatus of claim 94, wherein said second apparatus comprises:

digital processing apparatus; and

a computer program operative to run on said digital processing apparatus, said computer program being adapted to receive data relating to said at least two physiologic parameters and generate said scaling factor based at least in part thereon.

97. Apparatus adapted to measure the blood pressure of a living subject, comprising:

first apparatus adapted to generate a signal relating to the pressure applied thereto; and

second apparatus configured to scale said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) and the pulse pressure (PP) of said subject.

98. Apparatus adapted to measure the blood pressure of a living subject, comprising:

first apparatus adapted to generate a signal relating to the pressure applied thereto; and

second apparatus configured to scale said unscaled pressure values using a scaling factor, said scaling factor being related to the body mass index (BMI) and the wrist circumference (WC) of said subject.

99. Apparatus adapted to measure the pressure in the blood vessel of a living subject, comprising:

a transducer adapted to generate a signal relating to the pressure applied thereto;

first apparatus adapted to maintain said transducer proximate to said blood vessel; and

second apparatus in operative communication with said transducer and configured to;

determine the level of compression where a desired condition of the pressure associated with said blood vessel exists based at least in part on the pressure signal generated by said transducer;

substantially maintain said level of compression where said desired condition exists;

measure at least one pressure value using said transducer while said desired condition exists; and

scale said at least one pressure value based at least in part on a physiologic index of said subject to produce a scaled value, said scaled value being substantially representative of the actual pressure within said blood vessel.

100. The apparatus of claim 99, wherein said second apparatus is configured to generate at least one control signal used by said first apparatus to substantially maintain said level of compression using at least said transducer.

101. The apparatus of claim 99, further comprising a bias element disposed proximate to said transducer, said bias element biasing at least a portion of tissue proximate to said blood vessel so as to mitigate the effects thereof on said measurement of at least one pressure value.

102. The apparatus of claim 100, further comprising a bias element disposed proximate to said transducer, said bias element biasing at least a portion of tissue proximate to said blood vessel during said compression so as to mitigate the effects thereof on said measurement of at least one pressure value.

103. Apparatus adapted to measure the blood pressure of a living subject, comprising:

first apparatus adapted to generate a signal relating to the pressure applied thereto, said applied pressure being applied at least in part by tissue interposed between said first apparatus and a blood vessel of said subject;

second apparatus disposed proximate to said first apparatus and adapted to mitigate the effects of said tissue on said applied pressure; and

third apparatus configured to scale said unscaled pressure values using a scaling factor, said scaling factor comprising a physiologic index of said subject, said physiologic index formed by relating at least two physiologic parameters associated with said subject.

104. The apparatus of claim 103, wherein said second apparatus comprises a bias element substantially encircling at least a portion of said first apparatus.

105. The apparatus of claim 104, further comprising applanation apparatus adapted to controllably press at least a portion of said first and second apparatus against said tissue.

106. A method of measuring the blood pressure of a living subject, comprising:

a step for measuring unscaled pressure values from a blood vessel of said subject; and

a step for scaling said unscaled pressure values using a scaling factor, said scaling factor comprising a physiologic index of said subject, said physiologic index formed by performing a step for relating at least two physiologic parameters associated with said subject.

107. Apparatus adapted to measure the blood pressure of a living subject, comprising:

means for generating a signal relating to the pressure applied thereto; and

means for scaling said unscaled pressure values using a scaling factor, said scaling factor comprising a physiologic index of said subject, said physiologic index formed by relating at least two physiologic parameters associated with said subject.