CA1327388C - Noninvasive continuous mean arterial blood pressure monitor - Google Patents
Noninvasive continuous mean arterial blood pressure monitorInfo
- Publication number
- CA1327388C CA1327388C CA000580744A CA580744A CA1327388C CA 1327388 C CA1327388 C CA 1327388C CA 000580744 A CA000580744 A CA 000580744A CA 580744 A CA580744 A CA 580744A CA 1327388 C CA1327388 C CA 1327388C
- Authority
- CA
- Canada
- Prior art keywords
- segment
- patient
- output signal
- cardiac
- blood flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/021—Measuring pressure in heart or blood vessels
- A61B5/02108—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics
- A61B5/02125—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics of pulse wave propagation time
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/021—Measuring pressure in heart or blood vessels
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/026—Measuring blood flow
- A61B5/0295—Measuring blood flow using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/053—Measuring electrical impedance or conductance of a portion of the body
- A61B5/0535—Impedance plethysmography
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7235—Details of waveform analysis
- A61B5/7239—Details of waveform analysis using differentiation including higher order derivatives
Abstract
NONINVASIVE CONTINUOUS MEAN ARTERIAL BLOOD PRESSURE MONITOR
Abstract of the Disclosure An apparatus and a method use noninvasive electrical bioimpedance measurements to monitor the means arterial blood pressure of a patient on a continuous (heartbeat-by-heartbeat) basis. The apparatus and method process the electrical impedance across two segments of body tissue to provide a signal for each segment that indicates the increase in blood flow in each segment at the beginning of each cardiac cycle. The apparatus and method process the signals corresponding to each segment to measure the arterial pulse propagation delay between the two segments.
The arterial pulse propagation delay is inversely related to the mean arterial blood pressure of the patient. The apparatus and method use the measured arterial pulse propagation delay to calculate the means arterial blood pressure of the patient. The cardiac output of the patient is also advantageously measured and the cardiac index of the patient calculated from the cardiac output. The cardiac index and the mean arterial blood pressure are then used by the apparatus and method to calculate the left cardiac work index and the systemic vascular resistance index of the patient.
Abstract of the Disclosure An apparatus and a method use noninvasive electrical bioimpedance measurements to monitor the means arterial blood pressure of a patient on a continuous (heartbeat-by-heartbeat) basis. The apparatus and method process the electrical impedance across two segments of body tissue to provide a signal for each segment that indicates the increase in blood flow in each segment at the beginning of each cardiac cycle. The apparatus and method process the signals corresponding to each segment to measure the arterial pulse propagation delay between the two segments.
The arterial pulse propagation delay is inversely related to the mean arterial blood pressure of the patient. The apparatus and method use the measured arterial pulse propagation delay to calculate the means arterial blood pressure of the patient. The cardiac output of the patient is also advantageously measured and the cardiac index of the patient calculated from the cardiac output. The cardiac index and the mean arterial blood pressure are then used by the apparatus and method to calculate the left cardiac work index and the systemic vascular resistance index of the patient.
Description
1 327388 ``~
~OMED . 2 3A PATENT
NONINVASIVE CONTINUOUS MEAN ARTERIAL BLOOD PRESSIJRE MONITOR
Background o~f_thelnvention The present invention relates to an apparatus and a 5 method that measure mean arterial blood pressure of a patient, and, more specifically, that provide noninvasive continuous recording and analyzing of the rate of impedance changes in two sections of the patient's body in order to continuously track mean arterial blood pressure. Still lo more specifically, the present invention relate~ to a method for continuously and noninvasively measuring both mean arterial blood pressure, left cardiac work index, and systemic vascular resistance index, utilizing an apparatus sapable of miniaturization.
Mean arterial blood pressure (MAP) and cardiac index (CI) together define the forces and mechanisms involved in the circulation of blood through the cardiovascular system of a body. Measurement o~ MAP and CI when a patient is at rest (i.e., when a patient's body is in an inactive state~
20 determines whether a patient has normal or abnor~al blood pressure and blood flow. For example, MAP values indicate whether a patient has low blood pressure ~hypotensive), normal blood pressure (normotensive), or high blood pressure (hypertensive)~ and CI values indicate whether a 25 patient's blood is in a low, normal, or high flow state.
Measurement of MAP and CI provîdes invaluable clinical information for "quantifying" the extent of blood circulation abnormalities, indicating the optimal course ~or therapy, managing patient progress, and establishing 30 checkpoints for rehabilitation in a patient in whom fluid status control is essential. In addition, MAP and CI
measurements define other important blood circulation information and mechanisms, such as oxygen transport characteristics of the cardiovascular system. For example, 35 the left cardiac work index (LCWI) is equal to MAP
~OMED . 2 3A PATENT
NONINVASIVE CONTINUOUS MEAN ARTERIAL BLOOD PRESSIJRE MONITOR
Background o~f_thelnvention The present invention relates to an apparatus and a 5 method that measure mean arterial blood pressure of a patient, and, more specifically, that provide noninvasive continuous recording and analyzing of the rate of impedance changes in two sections of the patient's body in order to continuously track mean arterial blood pressure. Still lo more specifically, the present invention relate~ to a method for continuously and noninvasively measuring both mean arterial blood pressure, left cardiac work index, and systemic vascular resistance index, utilizing an apparatus sapable of miniaturization.
Mean arterial blood pressure (MAP) and cardiac index (CI) together define the forces and mechanisms involved in the circulation of blood through the cardiovascular system of a body. Measurement o~ MAP and CI when a patient is at rest (i.e., when a patient's body is in an inactive state~
20 determines whether a patient has normal or abnor~al blood pressure and blood flow. For example, MAP values indicate whether a patient has low blood pressure ~hypotensive), normal blood pressure (normotensive), or high blood pressure (hypertensive)~ and CI values indicate whether a 25 patient's blood is in a low, normal, or high flow state.
Measurement of MAP and CI provîdes invaluable clinical information for "quantifying" the extent of blood circulation abnormalities, indicating the optimal course ~or therapy, managing patient progress, and establishing 30 checkpoints for rehabilitation in a patient in whom fluid status control is essential. In addition, MAP and CI
measurements define other important blood circulation information and mechanisms, such as oxygen transport characteristics of the cardiovascular system. For example, 35 the left cardiac work index (LCWI) is equal to MAP
Claims (27)
1. A noninvasive apparatus for continuously monitoring the mean arterial blood pressure of a patient, comprising:
first electrical bioimpedance measuring means electrically connectable to a first segment of the patient's body, for sensing the increase in blood flow in the first segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart and for generating a first output signal that indicates when the increase in blood flow occurs in the first segment;
second electrical bioimpedance measuring means electrically connectable to a second segment of the patient's body for sensing the increase in blood flow in the second segment caused by the ejection of blood into arteries during the ventricular contraction of the patient's heart and for generating a second output signal that indicates when the increase in blood flow occurs in the second segment, the second segment located at a distance from the first segment so that the increase in blood flow in the second segment occurs at a time interval after the increase in blood flow in the first segment, said time interval between said first output signal and said second output signal proportional to the distance between the first segment and the second segment and inversely proportional to the mean arterial blood pressure of the patient; and electronic measuring and calculating means for measuring the time interval between the first output signal and the second output signal, and for calculating the mean arterial blood pressure of the patient based upon the measured time interval and the distance between the first segment and the second segment.
first electrical bioimpedance measuring means electrically connectable to a first segment of the patient's body, for sensing the increase in blood flow in the first segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart and for generating a first output signal that indicates when the increase in blood flow occurs in the first segment;
second electrical bioimpedance measuring means electrically connectable to a second segment of the patient's body for sensing the increase in blood flow in the second segment caused by the ejection of blood into arteries during the ventricular contraction of the patient's heart and for generating a second output signal that indicates when the increase in blood flow occurs in the second segment, the second segment located at a distance from the first segment so that the increase in blood flow in the second segment occurs at a time interval after the increase in blood flow in the first segment, said time interval between said first output signal and said second output signal proportional to the distance between the first segment and the second segment and inversely proportional to the mean arterial blood pressure of the patient; and electronic measuring and calculating means for measuring the time interval between the first output signal and the second output signal, and for calculating the mean arterial blood pressure of the patient based upon the measured time interval and the distance between the first segment and the second segment.
2. The apparatus of Claim 1, wherein said first electrical bioimpedance measuring means comprise:
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the first segment of the patient to cause current flow in said first segment;
means for sensing a voltage caused by said current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first body segment caused by the flow of blood in the first body segment during each cardiac cycle; and an electronic circuit connected to said sensing means, said electronic circuit receiving said voltage sensed by said sensing means and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the first segment of the patient to cause current flow in said first segment;
means for sensing a voltage caused by said current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first body segment caused by the flow of blood in the first body segment during each cardiac cycle; and an electronic circuit connected to said sensing means, said electronic circuit receiving said voltage sensed by said sensing means and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
3. The apparatus of Claim 2, wherein said electronic circuit includes a differentiator that generates a differentiated voltage that has a magnitude proportional to the rate of change of electrical bioimpedance in the first segment, said differentiated voltage having at least one peak corresponding to the maximum rate of increase in blood flow in the first segment caused by the ventricular contraction of the patient's heart.
4. The apparatus of Claim 1, wherein said second electrical bioimpedance measuring means comprises:
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the second segment of the patient to cause current flow in said second segment;
means for sensing a voltage caused by said current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second body segment caused by the flow of blood in the second body segment during each cardiac cycle; and an electronic circuit connected to said sensing means, said electronic circuit receiving said voltage sensed by said sensing means and generating a second output signal having a magnitude that changes in accordance with the blood flow in the second body segment during each cardiac cycle.
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the second segment of the patient to cause current flow in said second segment;
means for sensing a voltage caused by said current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second body segment caused by the flow of blood in the second body segment during each cardiac cycle; and an electronic circuit connected to said sensing means, said electronic circuit receiving said voltage sensed by said sensing means and generating a second output signal having a magnitude that changes in accordance with the blood flow in the second body segment during each cardiac cycle.
5. The apparatus of Claim 4, wherein said electronic circuit includes a differentiator that generates a differentiated voltage that has a magnitude proportional to the rate of change of electrical bioimpedance in the second segment, said differentiated voltage having at least one peak corresponding to the maximum rate of increase in blood flow in the second segment caused by the ventricular contraction of the patient's heart.
6. The apparatus of Claim 1, where said electronic measuring and calculating means comprise a microprocessor that is responsive to said first output signal from said first electrical bioimpedance measuring means and to said second output signal from said second electrical bioimpedance measuring means and that measures the time interval between the increase in blood flow indicated by said first output signal and the increase in blood flow indicated by said second output signal.
7. The apparatus of Claim 6, further comprising input means electrically connected to said microprocessor for providing data input to said microprocessor representative of the distance between the first and second segments.
8. The apparatus of Claim 1, wherein said electronic measuring and computing means generates an output signal that represents the mean arterial blood pressure of the patient.
9. The apparatus of Claim 1, further including a display device electrically connected to said electronic measuring and computing means that displays the mean arterial blood pressure of the patient.
10. The apparatus of Claim 1, wherein said electronic measuring and computing means includes a means for generating a time window that begins at a predetermined time after said increase in blood flow indicated by said first output signal and that has a predetermined duration, said electronic measuring and computing means monitoring said second output signal only during said time window to thereby reduce the probability of incorrect measurement of said time interval between the beginning of blood flow in the first segment and the beginning of blood flow in the second segment.
11. The apparatus of Claim 1, wherein said electronic measuring and computing calculates the mean arterial blood pressure of the patient in accordance with the following relationship:
where MAP is the calculated mean arterial blood pressure, D
is the vascular distance between the two body segments, APPD is the measured arterial pulse propagation delay, APPDoffset is an empirically determined offset in the measure delay, and SLOPE is an empirically determined relationship between the change in the measured delay and the change in the mean arterial blood pressure.
where MAP is the calculated mean arterial blood pressure, D
is the vascular distance between the two body segments, APPD is the measured arterial pulse propagation delay, APPDoffset is an empirically determined offset in the measure delay, and SLOPE is an empirically determined relationship between the change in the measured delay and the change in the mean arterial blood pressure.
12. The apparatus of Claim 1, wherein said first electrical bioimpedance measuring means provides an output signal having a magnitude corresponding to the measured cardiac output of the patient, said electronic measuring and computing means converts the measured cardiac output to a magnitude corresponding to the cardiac index of the patient, and said electronic measuring and computing means calculates the left cardiac work index of the patient in accordance with the following relationship:
LCWI = MAP X CI X CONSTANT
where LCWI is the left cardiac work index of the patient, MAP is the mean arterial blood pressure of the patient, CI
is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
LCWI = MAP X CI X CONSTANT
where LCWI is the left cardiac work index of the patient, MAP is the mean arterial blood pressure of the patient, CI
is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
13. The apparatus of Claim 1, wherein said first electrical bioimpedance measuring means provides an output signal having a magnitude corresponding to the measured cardiac output of the patient, said electronic measuring and computing circuit converts the measured cardiac output to a magnitude corresponding to the cardiac index of the patient, and said electronic measuring and computing means calculates vascular resistance index of the patient in accordance with the following relationship:
SVRI = (MAP/CI) X CONSTANT
where SVRI is the systemic vascular resistance index of the patient, MAP is the mean arterial blood pressure of the patient, CI is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
SVRI = (MAP/CI) X CONSTANT
where SVRI is the systemic vascular resistance index of the patient, MAP is the mean arterial blood pressure of the patient, CI is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
14. The apparatus of Claim 1, wherein:
said first electrical bioimpedance measuring means comprises:
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the first and second segments of the patient to cause current flow in said first and second segments;
first sensing means for sensing a voltage caused by current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first body segment caused by the flow of blood in the first body segment during each cardiac cycle: and a first electronic circuit connected to said first sensing means, said first electronic circuit receiving said voltage sensed by said first sensing means and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle: and said second electrical bioimpedance measuring means comprises:
second sensing means for sensing a voltage caused by current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second body segment caused by the flow of blood in the second body segment during each cardiac cycle; and a second electronic circuit connected to said second sensing means, said second electronic circuit receiving said voltage sensed by said second sensing means and generating a second output signal having a magnitude that changes in accordance with the blood flow in the second body segment during each cardiac cycle.
said first electrical bioimpedance measuring means comprises:
a current source having a high-frequency constant amplitude electrical current output;
means for injecting the output of said current source into the first and second segments of the patient to cause current flow in said first and second segments;
first sensing means for sensing a voltage caused by current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first body segment caused by the flow of blood in the first body segment during each cardiac cycle: and a first electronic circuit connected to said first sensing means, said first electronic circuit receiving said voltage sensed by said first sensing means and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle: and said second electrical bioimpedance measuring means comprises:
second sensing means for sensing a voltage caused by current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second body segment caused by the flow of blood in the second body segment during each cardiac cycle; and a second electronic circuit connected to said second sensing means, said second electronic circuit receiving said voltage sensed by said second sensing means and generating a second output signal having a magnitude that changes in accordance with the blood flow in the second body segment during each cardiac cycle.
15. A method for noninvasively monitoring the mean arterial blood pressure of a patient, comprising:
electrically connecting a first electrical bioimpedance measuring device to a first segment of the patient' body;
sensing the increase in blood flow in the first segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart;
generating a first output signal that indicates when the increase in blood flow occurs in the first segment;
electrically connecting a second electrical bioimpedance measuring device to a second segment of the patient's body;
sensing the increase in blood flow in the second segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart;
generating a second output signal that indicates when the increase in blood flow occurs in the second segment;
locating the second segment at a distance from the first segment so that the increase in blood flow in the second segment occurs at a time interval after the increase in blood flow in the first segment, said time interval between said first output signal and said second output signal proportional to the distance between the first segment and the second segment and inversely proportional to the mean arterial blood pressure of the patient;
measuring the time interval between the first output signal and the second output signal; and calculating the mean arterial blood pressure of the patient based upon the measured time interval and the distance between the first segment and the second segment.
electrically connecting a first electrical bioimpedance measuring device to a first segment of the patient' body;
sensing the increase in blood flow in the first segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart;
generating a first output signal that indicates when the increase in blood flow occurs in the first segment;
electrically connecting a second electrical bioimpedance measuring device to a second segment of the patient's body;
sensing the increase in blood flow in the second segment caused by the ejection of blood into the arteries during the ventricular contraction of the patient's heart;
generating a second output signal that indicates when the increase in blood flow occurs in the second segment;
locating the second segment at a distance from the first segment so that the increase in blood flow in the second segment occurs at a time interval after the increase in blood flow in the first segment, said time interval between said first output signal and said second output signal proportional to the distance between the first segment and the second segment and inversely proportional to the mean arterial blood pressure of the patient;
measuring the time interval between the first output signal and the second output signal; and calculating the mean arterial blood pressure of the patient based upon the measured time interval and the distance between the first segment and the second segment.
16. The method of Claim 15, wherein saID step of sensing the blood flow in said first segment comprises the steps of:
generating a high-frequency constant amplitude electrical current;
injecting said current into the first segment of the patient;
sensing a voltage caused by current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first segment caused by the flow of blood in the first segment during each cardiac cycle; and amplifying said sensed voltage and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
generating a high-frequency constant amplitude electrical current;
injecting said current into the first segment of the patient;
sensing a voltage caused by current flow through the first segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the first segment caused by the flow of blood in the first segment during each cardiac cycle; and amplifying said sensed voltage and generating a first output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
17. The method of Claim 16, further including the step of generating a differentiated voltage that has a magnitude proportional to the rate of change of electrical bioimpedance in the first segment, said differentiated voltage having at least one peak corresponding to the maximum rate of increase in blood flow in the first segment caused by the ventricular contraction of the patient's heart.
18. The method of Claim 17, wherein said step of sensing the blood flow in said second segment comprises the steps of:
generating a high-frequency constant amplitude electrical current;
injecting said current into the second segment of the patient;
sensing a voltage caused by current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second segment caused by the flow of blood in the second segment during each cardiac cycle; and amplifying said sensed voltage and generating a second output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
generating a high-frequency constant amplitude electrical current;
injecting said current into the second segment of the patient;
sensing a voltage caused by current flow through the second segment of the patient, said voltage having a magnitude that varies in accordance with changes in electrical bioimpedance of the second segment caused by the flow of blood in the second segment during each cardiac cycle; and amplifying said sensed voltage and generating a second output signal having a magnitude that changes in accordance with the blood flow in the first segment during each cardiac cycle.
19. The method of Claim 18, further including the step of generating a differentiated voltage that has a magnitude proportional to the rate of change of electrical bioimpedance in the first segment, said differentiated voltage having at least one peak corresponding to the maximum rate of increase in blood flow in the second segment caused by the ventricular contraction of the patient's heart.
20. The method of Claim 15, wherein said calculating step is performed by a microprocessor and further including the step of inputting data to said microprocessor representative of the distance between the first and second segments.
21. The method of Claim 15, further including the step of generating an output signal that represents the mean arterial blood pressure of the patient.
22. The method of Claim 15, further including the step of displaying the mean arterial blood pressure of the patient.
23. The method of Claim 15, further including the step of generating a time window that begins at a predetermined time after said increase in blood flow indicated by said first output signal and that has a predetermined duration, said measuring step operational to measure the end of said time interval only during said time window to thereby reduce the probability of incorrect measurement of said time interval between the beginning of blood flow in the first segment and the beginning of blood flow in the second segment.
24. The method of Claim 15, wherein aid calculating step is performed in accordance with the following relationship:
where MAP is the calculated mean arterial blood pressure, D
is the vascular distance between the two segments, APPD is the measured arterial pulse propagation delay, APPDoffset is an empirically determined offset in the measure delay, and SLOPE is an empirically determined relationship between the change in the measured delay and the change in the mean arterial blood pressure.
where MAP is the calculated mean arterial blood pressure, D
is the vascular distance between the two segments, APPD is the measured arterial pulse propagation delay, APPDoffset is an empirically determined offset in the measure delay, and SLOPE is an empirically determined relationship between the change in the measured delay and the change in the mean arterial blood pressure.
25. The method of Claim 24, wherein SLOPE is approximately -0.875 milliseconds per meter per torr and APPDoffset is approximately 210 milliseconds.
26. The method of Claim 15, further including the steps of:
providing an output signal having a magnitude corresponding to the measured cardiac output of the patient:
converting the measured cardiac output to a magnitude corresponding to the cardiac index of the patient; and calculating the left cardiac work index of the patient in accordance with the following relationship:
LCWI = MAP x CI x CONSTANT
where LCWI is the left cardiac work index of the patient, MAP is the mean arterial blood pressure of the patient, CI
is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
providing an output signal having a magnitude corresponding to the measured cardiac output of the patient:
converting the measured cardiac output to a magnitude corresponding to the cardiac index of the patient; and calculating the left cardiac work index of the patient in accordance with the following relationship:
LCWI = MAP x CI x CONSTANT
where LCWI is the left cardiac work index of the patient, MAP is the mean arterial blood pressure of the patient, CI
is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
27. The method of Claim 15, further including the steps of:
providing an output signal having a magnitude corresponding to the measured cardiac output of the patient:
converting the measured cardiac output to a magnitude corresponding to the cardiac index of the patient; and calculating the systemic vascular resistance index of the patient in accordance with the following relationship:
SVRI = (MAP/CI) x CONSTANT
where SVRI is the systemic vascular resistance index of the patient, MAP is the mean arterial blood pressure of the patient, CI is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
providing an output signal having a magnitude corresponding to the measured cardiac output of the patient:
converting the measured cardiac output to a magnitude corresponding to the cardiac index of the patient; and calculating the systemic vascular resistance index of the patient in accordance with the following relationship:
SVRI = (MAP/CI) x CONSTANT
where SVRI is the systemic vascular resistance index of the patient, MAP is the mean arterial blood pressure of the patient, CI is the cardiac index of the patient, and CONSTANT is a constant selected for the parameters of the cardiac index and the pressure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/111,699 US4807638A (en) | 1987-10-21 | 1987-10-21 | Noninvasive continuous mean arterial blood prssure monitor |
| US111,699 | 1987-10-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1327388C true CA1327388C (en) | 1994-03-01 |
Family
ID=22339988
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000580744A Expired - Fee Related CA1327388C (en) | 1987-10-21 | 1988-10-20 | Noninvasive continuous mean arterial blood pressure monitor |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4807638A (en) |
| EP (1) | EP0441777A4 (en) |
| JP (1) | JPH03504202A (en) |
| CA (1) | CA1327388C (en) |
| WO (1) | WO1989003656A1 (en) |
Families Citing this family (120)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990000367A1 (en) * | 1988-07-14 | 1990-01-25 | Bomed Medical Manufacturing, Ltd. | Management of hemodynamic state of a patient |
| US5103828A (en) * | 1988-07-14 | 1992-04-14 | Bomed Medical Manufacturing, Ltd. | System for therapeutic management of hemodynamic state of patient |
| US5031629A (en) * | 1989-06-02 | 1991-07-16 | Demarzo Arthur P | Hypertension analyzer apparatus |
| US5086776A (en) * | 1990-03-06 | 1992-02-11 | Precision Diagnostics, Inc. | Apparatus and method for sensing cardiac performance |
| DE59107232D1 (en) * | 1990-07-18 | 1996-02-22 | Avl Medical Instr Ag | Device and method for measuring blood pressure |
| US5063937A (en) * | 1990-09-12 | 1991-11-12 | Wright State University | Multiple frequency bio-impedance measurement system |
| AU8924491A (en) * | 1990-10-23 | 1992-05-20 | Hypertension Diagnostics, Inc. | Method and apparatus for measuring cardiac output |
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1987
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1988
- 1988-10-17 WO PCT/US1988/003647 patent/WO1989003656A1/en not_active Application Discontinuation
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- 1988-10-17 JP JP1500135A patent/JPH03504202A/en active Pending
- 1988-10-20 CA CA000580744A patent/CA1327388C/en not_active Expired - Fee Related
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| US4807638A (en) | 1989-02-28 |
| WO1989003656A1 (en) | 1989-05-05 |
| JPH03504202A (en) | 1991-09-19 |
| EP0441777A1 (en) | 1991-08-21 |
| EP0441777A4 (en) | 1992-09-16 |
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