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US 4,562,843 AGranted
System for determining characteristics of blood flow
OwnerLjubomir Djordjevich, Max S. Sadoveinventors
Life of this patent
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Abstract
Method and apparatus are disclosed for determination and display of hemodynamic characteristic values of a patient in a variety of statistical forms and in relative or absolute terms, the measurement determination being made by non-invasive impedance plethysmography under control of a central processor. A characteristic value representative of variation of blood vessel cross-sectional area is measured across a patient's body section, blood pressure is measured in the body in simultaneity with the characteristic value, and signals representative of the characteristic value and blood pressure are then processed to obtain the hemodynamic characteristic values.
Claims80
A method for measuring a hemodynamic characteristic of a living body having elastic blood vessels comprising the steps of:
- measuring a characteristic value across a section of said body, said characteristic value being at least representative of the variation in cross-sectional area of the blood vessels within that section;
- measuring blood pressure in said body simultaneously with the measurement of said characteristic value;
- and
- processing signals representative of the characteristic value and the blood pressure measurements with a processing means to obtain an electrical signal representing the hemodynamic characteristic;
- said processing step including the step of utilizing at least one hemodynamic equation which relates said characteristic value, said blood pressure and the modulus of elasticity of the blood vessels within said section as a function, and including the step of calculating said modulus of elasticity.
2 more elements
An apparatus for determining the value of a characteristic of blood flow in a section of a living body having elastic blood vessels comprising:
- an inpedance plethysmograph for connection to said body having electrodes for attachment at spaced positions along said section of said body for selectively outputting a signal representative of the value of the electrical impedance of said body section,
- means for simultaneously measuring blood pressure of said living body and for outputting a signal representative thereof;
- and
- a processor having means for receiving said signals representing said electrical impedance and said blood pressure, means for storing corresponding values of the blood pressure and electrical impedance signals as a plurality of sets;
- and means for processing said simultaneously measured sets of said signals with corresponding sets of hemodynamic equations which relate said impedance, said blood pressure, and the modulus of elasticity of the blood vessels within said section as a function so as to calculate said modulus of elasticity, and so as to generate said blood flow characteristic.
2 more elements
A method of measuring a hemodynamic characteristic across a section of a living body having elastic blood vessels comprising the steps of:
- determining the viscosity and resistivity of the blood of the body;
- attaching a plethysmograph for measuring an electrical impedance across said section of the body said impedance being at least representative of the variance in the cross sectional area of the blood vessels within said section;
- attaching means for measuring blood pressure;
- measuring personal characteristics of said body;
- processing signals representative of the characteristic value and the blood pressure measurements with a processing means to obtain an electrical signal representing the hemodynamic characteristic;
- said processing step including the step of utilizing at least one hemodynamic equation which relates said characteristic value, said blood pressure and the modulus of elasticity of the blood vessels within said section as a function, and including the step of calculating said modulus of elasticity;
- and
- further processing said personal characteristics with a hemodynamic equation which relates said hemodynamic characteristic as a function of the calculated modulus of elasticity of said blood vessels, said viscosity, said resistivity, and said personal characteristics to determine the hemodynamic characteristic.
5 more elements
A method of determining the kinetic energy of blood flow through a blood vessel comprising the steps of:
- measuring an electrical property across a section of a body overlying the section of the blood vessel,
- measuring blood pressure in said body simultaneously with the measurement of the electrical property;
- processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a first value representing the mean area of the section of the blood vessel, a second value representing the rate of blood flow, and a third value representing the mean blood velocity;
- and
- processing values representative of the rate of blood flow and mean blood velocity to obtain a value representing the kinetic energy of blood flow.
2 more elements
A method for measuring the total heart power comprising the steps of:
- measuring an electrical property across a section of a body overlying the section of the blood vessel,
- measuring blood pressure in said body simultaneously with the measurement of the electrical property;
- processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a first value representing potential energy of blood flow, and a second value representing kinetic energy of blood flow;
- and
- processing the values representing the potential and the kinetic energies of the blood flow to determine the value of the total heart power.
2 more elements
A system for measuring a hemodynamic characteristic comprising:
- means for non-invasively measuring a characteristic value across a section of a living body,
- means for non-invasively measuring blood pressure in said body simultaneously with the measurement of said characteristic value;
- and
- means for processing signals representative of the characteristic value and the blood pressure measurements through an electronic device to obtain an electrical signal representing the hemodynamic characteristic.
1 more element
An apparatus for measuring hemodynamic characteristics comprising:
- means for measuring across a section of a living body and determining a characteristic value;
- means for measuring blood pressure in said body simultaneously with the measurement of the characteristic value;
- means for determining a hemodynamic characteristics from the simultaneous measurements;
- and
- means for displaying the determined hemodynamic characteristics.
2 more elements
A system for measuring and determining a hemodynamic characteristic comprising:
- means for determining viscosity and resistivity of blood of a patient;
- means for attaching a plethysmograph to measure an electrical property across a portion of the patient's body, means for simultaneously measuring blood pressure and the electrical property across the section of the patient;
- means for inputting personal characteristics of the patient;
- and
- means for processing the personal characteristics and the simultaneously measured values of the blood pressure and the electrical property, to determining the hemodynamic characteristic.
2 more elements
A system for measuring the cross-sectional area of a section of a blood vessel comprising:
- means for measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for measuring blood pressure in said body simultaneously with the measurement of the electrical property,
- means for processing values representative of the simultaneous measurements of the blood pressure and the electrical property to obtain a value representing the cross-sectional area of the section of the blood vessel.
A system for measuring the elasticity of a section of a blood vessel comprising:
- means for measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for measuring blood pressure in said body simultaneously with the measurement of the electrical property, and
- means for processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a value representing the elasticity of the section of the blood vessel.
A system for measuring the rate of blood flow in a section of a blood vessel comprising:
- means for measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for measuring blood pressure in said body simultaneously with with the measurement of the electrical property, and
- means for processing values representative of multiple sets of simultaneous measurements of the blood pressure and the electrical property to obtain a value representing the rate of blood flow in the section of the blood vessel.
A system for measuring the mean velocity of blood across a section of a blood vessel comprising:
- means for noninvasively measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for noninvasively measuring blood pressure in said body simultaneously with the measurement of the electrical property;
- means for processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a value representing the mean area of the section of the blood vessel;
- means for processing values representative of multiple sets of the simultaneous measurements to obtain a value representating the rate of blood flow in the section of the blood vessel, and
- means for deriving the mean velocity of blood responsive to the rate of blood and the mean area.
2 more elements
A system for measuring vascular resistance comprising:
- means for measuring blood pressure in said body at two points on said body, overlying said section;
- means for processing values representative of the two-point measurements of the blood pressure to obtain a value representing differential blood pressure of the section of the blood vessel,
- means for determining cardiac output;
- and
- means for determining vascular resistance as a function of the cardiac output and the differential blood pressure.
2 more elements
A system for determining the kinetic energy of blood flow through a blood vessel comprising:
- means for measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for measuring blood pressure in said body simultaneously with the measurement of the electrical property;
- means for processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a first value representing the rate of blood flow, and a second value representing the mean blood velocity;
- and
- means for processing values representative of the rate of blood flow and mean blood velocity to obtain a value representing the kinetic energy of blood flow.
2 more elements
A system for measuring the total heart power comprising:
- means for measuring an electrical property across a section of a body overlying the section of the blood vessel,
- means for measuring blood pressure in said body simultaneously with the measurement of the electrical property;
- means for processing values representative of multiple sets of the simultaneous measurements of the blood pressure and the electrical property to obtain a first value representing potential energy of blood flow, and a second value representing kinetic energy of blood flow;
- and
- means for processing the values representing the potential and the kinetic energies of blood flow to determine the value of the total heart power.
2 more elements
A method for measuring a hemodynamic characteristic in a section of a living body having elastic blood vessels comprising:
- measuring an electrical parameter across said body section to determine an impedance value for said section;
- measuring a blood pressure value in said body simultaneously with the measurement of the impedance value;
- determining impedance values corresponding to the systolic and the diastolic blood pressure of the body;
- calculating an elasticity value E from the simultaneous blood pressure and impedance measurements corresponding to said systolic and diastolic pressures, and a third pair of measurements of mean pressure and impedance, and determining the respective cross sectional area of the blood vessels within said section for each set of measurements from the respective pressure and impedance measurements and E.
1 more element
A method for measuring the instantaneous rate of blood flow in a section of a living body having elastic blood vessels comprising the steps of:
- measuring an electrical parameter across a section of said body having the blood vessels within, said electrical property being at least representative of the variance in cross sectional area of the blood vessels within that section;
- measuring blood pressure in said body simultaneously with the measurement of said electrical parameter;
- processing values of multiple sets of simultaneous measurements of the blood pressure and the electrical parameter;
- solving a set of hemodynamic equations which relates the axial velocity of the blood in said vessels as a function of various unknowns, said equations having of the same number of unknown variables as the number of measurement sets, wherein one of the unknowns is the modulus of elasticity of the blood vessels within said section;
- multiplying the axial velocity of the blood flow by the cross sectional area of the blood vessels of said section to yield an instantaneous rate of blood flow therethrough.
2 more elements
Dependencies are inferred from the claim text.