US4785823A — Methods and apparatus for performing in vivo bloo…

Claim 1

Independent Claim 166 words

Apparatus for use in in vivo blood thermodilution procedures comprising: a first electrode insertable in a blood vessel so that the first electrode is in electrical contact with the blood flowing in the blood vessel; a second electrode insertable in the blood vessel so that the second electrode is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; first means for conveying a first electrical potential to the first electrode; second means for conveying a second electrical potential to the second electrode so that when the first and second electrical potentials are different from one another, electrical current flows between the first second electrodes through the blood flowing in the blood vessel to heat the blood through which said current flows; and a temperature sensor insertable in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 2

Dependent Claim 166 words

Apparatus for use in in vivo blood thermodilution procedures comprising: a first electrode insertable in a blood vessel so that the first electrode is in electrical contact with the blood flowing in the blood vessel; a second electrode insertable in the blood vessel so that the second electrode is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; first means for conveying a first electrical potential to the first electrode; second means for conveying a second electrical potential to the second electrode so that when the first and second electrical potentials are different from one another, electrical current flows between the first second electrodes through the blood flowing in the blood vessel to heat the blood through which said current flows; and a temperature sensor insertable in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 3

Dependent Claim 32 words

The apparatus defined in claim 1 further comprising: means disposed outside the body of the thermodilution procedure patient for applying an electrical potential difference to the first and second means for conveying.

Claim 4

Dependent Claim 35 words

The apparatus defined in claim 2 wherein the means for applying applies an alternating current potential difference having a frequency of at least about 20 KHz for a period of approximately 2 to 4 seconds.

Claim 5

Dependent Claim 31 words

The apparatus defined in claim 2 wherein the means for applying applies an alternating current potential difference having a frequency in the range from about 200 KHz to about 500 KHz.

Claim 6

Dependent Claim 31 words

The apparatus defined in claim 1 further comprising: means disposed outside the body of the thermodilution procedure patient for monitoring the output of the temperature sensor as a function of time.

Claim 7

Independent Claim 168 words

The method of performing an in vivo blood thermodilution procedure by heating a portion of the blood flowing in a blood vessel and monitoring the temperature of the blood at another point in the blood stream comprising the steps of: inserting a first electrode in the blood vessel so that the first electrode is in electrical contact with the blood flowing in the blood vessel; inserting a second electrode in the blood vessel so that the second electrode is spaced form the first electrode and in electrical contact with the blood flowing in the blood vessel; applying an electrical potential difference to the first and second electrodes so that an electrical current flows through the blood between the first and second electrodes and heats the blood through which the current flows; and inserting a temperature sensor in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 8

Independent Claim 168 words

The method of performing an in vivo blood thermodilution procedure by heating a portion of the blood flowing in a blood vessel and monitoring the temperature of the blood at another point in the blood stream comprising the steps of: inserting a first electrode in the blood vessel so that the first electrode is in electrical contact with the blood flowing in the blood vessel; inserting a second electrode in the blood vessel so that the second electrode is spaced form the first electrode and in electrical contact with the blood flowing in the blood vessel; applying an electrical potential difference to the first and second electrodes so that an electrical current flows through the blood between the first and second electrodes and heats the blood through which the current flows; and inserting a temperature sensor in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 9

Dependent Claim 26 words

The method defined in claim 6 wherein the electrical potential difference is an alternating current potential difference having a frequency of at least about 20 KHz.

Claim 10

Dependent Claim 22 words

The method defined in claim 6 wherein the electrical potential difference is applied for a period of approximately 2 to 4 seconds.

Claim 11

Dependent Claim 31 words

The method defined in claim 6 wherein the electrical potential difference is an alternating current potential difference having a frequency in the range from about 200 KHz to about 500 KHz.

Claim 12

Dependent Claim 23 words

The method defined in claim 6 further comprising the step of: monitoring the output of the temperature sensor as a function of time.

Claim 13

Dependent Claim 192 words

Apparatus for use in in vivo blood thermodilution procedures comprising: a longitudinal support member, at least a portion of which is longitudinally insertable into a longitudinal blood vessel so that the longitudinal axis of the inserted portion of the support member and the longitudinal axis of the blood vessel are substantially aligned; a first electrode disposed on the inserted portion of the support member so that it is in electrical contact with the blood flowing in the blood vessel; a second electrode disposed on the inserted portion of the support member so that it is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; means for conveying an electrical potential difference to the first and second electrodes for causing an electrical current to flow through the blood between the first and second electrodes and thereby heat the blood through which the current flows; and a temperature sensor disposed on the inserted portion of the support member at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 14

Dependent Claim 192 words

Apparatus for use in in vivo blood thermodilution procedures comprising: a longitudinal support member, at least a portion of which is longitudinally insertable into a longitudinal blood vessel so that the longitudinal axis of the inserted portion of the support member and the longitudinal axis of the blood vessel are substantially aligned; a first electrode disposed on the inserted portion of the support member so that it is in electrical contact with the blood flowing in the blood vessel; a second electrode disposed on the inserted portion of the support member so that it is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; means for conveying an electrical potential difference to the first and second electrodes for causing an electrical current to flow through the blood between the first and second electrodes and thereby heat the blood through which the current flows; and a temperature sensor disposed on the inserted portion of the support member at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 15

Dependent Claim 29 words

The apparatus defined in claim 11 further comprising: means disposed outside the body of the thermodilution procedure patient for applying the electrical potential difference to the means for conveying.

Claim 16

Dependent Claim 35 words

The apparatus defined in claim 12 wherein the means for applying applies an alternating current potential difference having a frequency of at least about 20 KHz for a period of approximately 2 to 4 seconds.

Claim 17

Dependent Claim 31 words

The apparatus defined in claim 12 wherein the means for applying applies an alternating current potential difference having a frequency in the range from about 200 KHz to about 500 KHz.

Claim 18

Dependent Claim 31 words

The apparatus defined in claim 11 further comprising: means disposed outside the body of the thermodilution procedure patient for monitoring the output of the temperature sensor as a function of time.

Claim 19

Independent Claim 151 words

The method of performing an in vivo thermodilution procedure on the blood flowing in a blood vessel comprising the steps of: providing a longitudinal support member having spaced first and second electrodes; inserting the support member longitudinally in a longitudinal blood vessel so that the longitudinal axes of the support member and the blood vessel are substantially aligned and so that each of the first and second electrodes is in electrical contact with the blood flowing in the blood vessel; applying an electrical potential difference to the first and second electrodes so that electrical current flows through the blood between the first and second electrodes and heats the blood through which the current flows; and inserting a temperature sensor in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 20

Independent Claim 151 words

The method of performing an in vivo thermodilution procedure on the blood flowing in a blood vessel comprising the steps of: providing a longitudinal support member having spaced first and second electrodes; inserting the support member longitudinally in a longitudinal blood vessel so that the longitudinal axes of the support member and the blood vessel are substantially aligned and so that each of the first and second electrodes is in electrical contact with the blood flowing in the blood vessel; applying an electrical potential difference to the first and second electrodes so that electrical current flows through the blood between the first and second electrodes and heats the blood through which the current flows; and inserting a temperature sensor in the blood vessel at a temperature sensing location downstream from the first and second electrodes for producing an output indication of the temperature of the blood at the temperature sensing location.

Claim 21

Dependent Claim 26 words

The method defined in claim 16 wherein the electrical potential difference is in alternating current potential difference having a frequency of at least about 20 KHz.

Claim 22

Dependent Claim 22 words

The method defined in claim 16 wherein the electrical potential difference is applied for a period of approximately 2 to 4 seconds.

Claim 23

Dependent Claim 31 words

The method defined in claim 16 wherein the electrical potential difference is an alternating current potential difference having a frequency in the range from about 200 KHz to about 500 KHz.

Claim 24

Dependent Claim 23 words

The method defined in claim 16 further comprising the step of: monitoring the output of the temperature sensor as a function of time.

Claim 25

Dependent Claim 151 words

A catheter for use in in vivo blood thermodilution procedures comprising: a longitudinal member insertable longitudinally into a blood vessel; a first electrode disposed on the longitudinal member so that the first electrode is in electrical contact with the blood flowing in the blood vessel; a second electrode disposed on the longitudinal member so that the second electrode is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; means for conveying an electrical potential difference longitudinally along the longitudinal member to the first and second electrodes for causing an electrical current to flow through the blood between the first and second electrodes and thereby heat the blood through which the current flows; and means disposed on the longitudinal member for sensing the temperature of the blood flowing in the blood vessel at a temperature sensing point downstream from the first and second electrodes.

Claim 26

Dependent Claim 151 words

A catheter for use in in vivo blood thermodilution procedures comprising: a longitudinal member insertable longitudinally into a blood vessel; a first electrode disposed on the longitudinal member so that the first electrode is in electrical contact with the blood flowing in the blood vessel; a second electrode disposed on the longitudinal member so that the second electrode is spaced from the first electrode and in electrical contact with the blood flowing in the blood vessel; means for conveying an electrical potential difference longitudinally along the longitudinal member to the first and second electrodes for causing an electrical current to flow through the blood between the first and second electrodes and thereby heat the blood through which the current flows; and means disposed on the longitudinal member for sensing the temperature of the blood flowing in the blood vessel at a temperature sensing point downstream from the first and second electrodes.

Claim 27

Dependent Claim 32 words

The catheter defined in claim 21 wherein the means for conveying is selected from the group consisting of coaxial cable, twisted pair wire, and twisted pair wire surrounded by an electromagnetic shield.

Claim 28

Dependent Claim 29 words

The catheter defined in claim 21 wherein the means for sensing the temperature of the blood comprises a thermistor disposed on the longitudinal member at the temperature sensing point.

Claim 29

Dependent Claim 28 words

The catheter defined in claim 23 wherein each of the first and second electrodes is an annular member extending annularly around the longitudinal axis of the longitudinal member.

Claim 30

Dependent Claim 50 words

The catheter defined in claim 24 wherein the longitudinal spacing between the first and second electrodes is in the range from about 0.5 to about 2.0 inches, and the width of each electrode, measured parallel to the longitudinal member, is in the range from about 0.1 to about 0.5 inches.

Claim 31

Dependent Claim 35 words

The catheter defined in claim 21 wherein the means for conveying an electrical potential difference comprises first and second electrical conductors respectively connected to the first and second electrodes and disposed in the longitudinal member.

Claim 32

Dependent Claim 29 words

The catheter defined in claim 21 wherein the means for sensing the temperature of the blood comprises a thermistor disposed on the longitudinal member at the temperature sensing point.

Claim 33

Dependent Claim 33 words

The catheter defined in claim 27 wherein the means for sensing the temperature of the blood further comprises first and second electrical leads disposed in the longitudinal member and connected to the thermistor.

Claim 34

Dependent Claim 38 words

The catheter defined in claim 21 further comprising: means associated with the longitudinal member for sensing the pressure of the blood flowing in the blood vessel at a pressure sensing point downstream from the first and second electrodes.

Claim 35

Dependent Claim 32 words

The catheter defined in claim 29 wherein the means for sensing the pressure of the blood comprises a first longitudinal conduit extending longitudinally through the longitudinal member to the pressure sensing point.

Claim 36

Dependent Claim 40 words

The catheter defined in claim 21 further comprising: an inflatable annular ring disposed on the longitudinal member at a location downstream from the first and second electrodes; and means associated with the longitudinal member for selectively inflating the annular ring.

Claim 37

Dependent Claim 27 words

The catheter defined in claim 31 wherein the means for selectively inflating comprises a second longitudinal conduit extending longitudinally through the longitudinal member to the annular ring.

Claim 38

Independent Claim 116 words

The method of determining cardiac output comprising the steps of: inserting into a blood vessel carrying substantially all the blood flowing through the heart a catheter having a plurality of electrodes in electrical contact with the blood and a temperature sensor in thermal contact with the blood at a temperature sensing location downstream from the electrodes for producing an output indicative of the temperature of the blood at the temperature sensing location; applying an electrical potential difference to the electrodes for a predetermined time interval so that electrical current flows between the electrodes through the blood and heats the blood through which the current flows; and monitoring the temperature sensor output as a function of time.

Claim 39

Independent Claim 116 words

The method of determining cardiac output comprising the steps of: inserting into a blood vessel carrying substantially all the blood flowing through the heart a catheter having a plurality of electrodes in electrical contact with the blood and a temperature sensor in thermal contact with the blood at a temperature sensing location downstream from the electrodes for producing an output indicative of the temperature of the blood at the temperature sensing location; applying an electrical potential difference to the electrodes for a predetermined time interval so that electrical current flows between the electrodes through the blood and heats the blood through which the current flows; and monitoring the temperature sensor output as a function of time.

Claim 40

Dependent Claim 26 words

The method defined in claim 33 wherein the electrical potential difference is applied to the electrodes for a time interval of approximately 2 to 4 seconds.

Claim 41

Dependent Claim 26 words

The method defined in claim 33 wherein the electrical potential difference is an alternating current potential difference having a frequency of at least about 20 KHz.

Claim 42

Dependent Claim 31 words

The method defined in claim 33 wherein the electrical potential difference is an alternating current potential difference having a frequency in the range from about 200 KHz to about 500 KHz.

Claim 43

Dependent Claim 61 words

The method defined in claim 33 wherein the catheter is inserted via a vein through the right atrium and right ventricle of the heart and into the pulmonary artery so that the electrodes are disposed in or near the right atrium and the temperature sensor is disposed in the pulmonary artery when the electrical potential difference is applied to the electrodes.

Claim 44

Dependent Claim 50 words

The method defined in claim 37 wherein the catheter includes an inflatable annular ring downstream from the electrodes and the temperature sensor, and wherein the method further comprises the step of inflating the annular ring during passage of that portion of the catheter through the right atrium and right ventricle.

Claim 45

Dependent Claim 62 words

The method defined in claim 38 wherein the catheter includes a blood pressure sensing point downstream from the annular ring, and wherein the method further comprises the step of monitoring the blood pressure at the blood pressure sensing point during insertion of the catheter and inserting the catheter until the pulmonary capillary wedge pressure is detected at the blood pressure sensing point.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-11-22	1992-05-23	1992-11-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-11-22	1996-05-23	1996-11-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-11-22	2000-05-23	2000-11-22	$7700.00	Window Closed / Lapsed

Methods and apparatus for performing in vivo blood thermodilution procedures

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