EP1408826A1 - Apparatus having redundant sensors for continuous monitoring of vital signs and related methods - Google Patents
Apparatus having redundant sensors for continuous monitoring of vital signs and related methodsInfo
- Publication number
- EP1408826A1 EP1408826A1 EP02742609A EP02742609A EP1408826A1 EP 1408826 A1 EP1408826 A1 EP 1408826A1 EP 02742609 A EP02742609 A EP 02742609A EP 02742609 A EP02742609 A EP 02742609A EP 1408826 A1 EP1408826 A1 EP 1408826A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signals
- vital sign
- value
- group
- sensors
- 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.)
- Withdrawn
Links
- 238000012544 monitoring process Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title claims description 26
- 230000036772 blood pressure Effects 0.000 claims description 35
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 230000006870 function Effects 0.000 claims description 8
- 239000008280 blood Substances 0.000 claims description 7
- 210000004369 blood Anatomy 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000005314 correlation function Methods 0.000 claims description 2
- 230000003213 activating effect Effects 0.000 claims 2
- 238000005259 measurement Methods 0.000 description 4
- 206010016717 Fistula Diseases 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000001143 conditioned effect Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229940079593 drug Drugs 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 230000003890 fistula Effects 0.000 description 2
- 230000002227 vasoactive effect Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 210000004204 blood vessel Anatomy 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000035487 diastolic blood pressure Effects 0.000 description 1
- 230000003205 diastolic effect Effects 0.000 description 1
- 210000000624 ear auricle Anatomy 0.000 description 1
- 208000015181 infectious disease Diseases 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000001356 surgical procedure Methods 0.000 description 1
- 230000035488 systolic blood pressure Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0002—Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
- A61B2560/02—Operational features
- A61B2560/0266—Operational features for monitoring or limiting apparatus function
- A61B2560/0271—Operational features for monitoring or limiting apparatus function using a remote monitoring unit
-
- 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
- A61B5/0205—Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
-
- 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
- A61B5/0285—Measuring or recording phase velocity of blood waves
Definitions
- This invention relates to devices for monitoring vital signs such as blood pressure, pulse rate, and oxygen saturation.
- the invention has particular application in devices for determining blood pressure by measuring a pulse wave velocity or pulse transit time.
- Equipment for monitoring the vital signs of subjects is widely used in clinical settings. Such devices may monitor various physiological signs including blood pressure, oxygen saturation, pulse rate and the like. Such devices typically include one or more sensors placed at suitable locations on the subject's body. Various different types of sensors may be used. The sensors may be of invasive types or of non- invasive types. Signals from the sensors are carried to the vital signs monitoring equipment where they are amplified, conditioned, and processed to determine values for the physiological parameters being measured.
- blood oxygen saturation may be measured by providing a small clip-on sensor which includes one or more light sources and one or more light detectors. Variations in the oxygen saturation of the subject's blood cause resulting variations in the intensity of light reaching the detector. These variations are superimposed upon a variation in the intensity of light reaching the detector which results from the subject's heartbeat pulses.
- a device equipped with this type of sensor can also be used to measure pulse rate. Various such devices are known.
- This invention provides an apparatus for monitoring one or more vital signs of a subject by using a number of sensors. Each sensor originates a signal, typically a pulse signal. A selection system determines performance criteria for a number of groups of signals. Each group includes one or more signals. The apparatus computes a estimated value for a vital sign by either computing a value from each group of signals and taking a weighted average with weights based upon the performance criterion or by selecting one of the groups of signals for which the performance criterion is best and computing the output value from that group of signals.
- FIG. 1 is a block diagram of a vital signs monitoring system according to the invention.
- Figure 2 is a view illustrating possible sensor locations for a vital signs monitoring system according to the invention.
- FIG. 3 is a block diagram of a vital signs monitoring system according to a specific embodiment of the invention. Description
- Figure 1 shows a system 10 according to the invention.
- Figure 1 comprises a plurality of sensors 12.
- the illustrated embodiment comprises three sensors, 12A, 12B and 12C.
- sensors 12A, 12B and 12C may be located on a subject's earlobe, finger and toe.
- Sensors 12 include at least one redundant sensor. That is, there is at least one more sensor 12 than is required for the type of measurement being made by system 10.
- the signal from each sensor 12 is conditioned and digitized in a signal conditioner 13.
- controller 14 comprises a processor 14A.
- Processor 14A runs software 15 stored in a program memory 15A.
- Software 15 receives the signals from all of sensors 12A through 12C by way of a suitable interface 18.
- a known relationship between DPTT and blood pressure is used to compute an estimated blood pressure from a DPTT value.
- the known relationship is obtained during a calibration process which involves measuring the subject's blood pressure by a separate accurate mechanism, and substantially simultaneously measuring the DPTT. These methods may be separately applied to each pair of signals from sensors 12.
- Controller 14 includes an automated selection system 16.
- Selection system 16 takes the signals from sensors 12 in distinct groups. In this case, "distinct" means that each group has a combination of signals from a different set of one or more sensors 12. Each group includes sufficient signals for the determination of a vital sign of interest. Where the groups include more than one signal, a signal from one sensor 12 may be included in more than one group. Selection system 16 identifies the best group of sensors 12 to be used for monitoring the vital sign in question. For example, where the vital sign is a blood pressure determined from a DPTT, each group of sensors comprises a pair of two sensors. For vital signs, such as pulse or blood oxygen saturation, which can be measured on the basis of the signal from one sensor the groups of sensors include one sensor each.
- the determination of the best group of sensors to use is preferably made based upon the stability of the signals originating at the sensors. For example, the following equation may be used to provide a performance criterion for the pair of signals (p i ,p i ) to be used in a DPTT blood pressure estimation:
- C [ Corr (p .,p .) / ⁇ . ⁇ .]
- C ⁇ j is the maximum value of the correlation coefficient of the paired signals (p ⁇ ,p j ) and q and O j are deviation measures for the two signals which are given as follows:
- the correlation function ( Corr) between the two signals can thus be calculated as:
- N is the number of samples used to calculate DPTT and determine the performance of the considered pair in a certain period of time.
- ⁇ ⁇ and ⁇ are respectively average signal values for the paired signals from the sensors under consideration.
- ⁇ may be given by the following equation:
- ⁇ j may be given by the following equation:
- the performance criterion C ⁇ j given by Equation (1) has a number of features which makes it suitable for use as a performance criterion for the pair of sensors under consideration.
- C-y is independent of the amplitudes of pulse signals p ⁇ and Pj and -l ⁇ &j ⁇ l .
- histogram-based calculation may be used in practice. Histogram-based calculation techniques which may be applied in this invention are described in Smith, " The Engineer and
- Histogram-based techniques have the advantage that computational complexity is not dependent upon the number of samples collected.
- Selection system 16 preferably comprises a function which tests for unacceptable signal values (as might result, for example, from the disconnection of a sensor) and, when such conditions are detected, forces the affected performance criterion C ⁇ j to be zero (or some other value that will cause the selection system 16 to not select the pairs of sensors affected by the unacceptable signal) .
- selection system 16 computes a blood pressure as a weighted average of the blood pressures computed from the signals of, each of three pairs of sensors. This weighted average may be expressed as follows:
- P a i2 P 12 + a 23 23 + a 3 l P 31 ⁇ 8 >
- weighting factors a i: ⁇ (where i and j are indices which represent the sensors in the pair of sensors under consideration) may be given by the following equation, where C i;/ is the performance criterion for the pair of sensors under consideration:
- selection system 16 may select one of the pairs of sensors which provides the best value for the subject's blood pressure (i.e. for which the performance criterion is the highest) .
- apparatus 10 presents the blood pressure derived from the signals of that pair of sensors 12 as the subject's blood pressure.
- This alternative embodiment of the invention is a special case of the weighted average according to equation (8) in which the values of aij which do not correspond to the group of signals having the best performance criterion are all zero and the atj corresponding to the group of signals having the best performance criterion is 1.
- a display 20 displays the computed blood pressure.
- a user input device, 24 such as a button panel, a graphical user interface, a touch screen, or the like is provided to permit users to control the operation of apparatus 10.
- user input device 24 permits a user to control whether selection system 16 selects signals from a specified pair of sensors 12, selects signals from the pair of sensors 12 which has the best performance criterion, or uses signals from all of sensors 12 in a blended average such as that of equation (7) .
- a digital input/output (I/O) connection 26 permits results to be delivered to other devices, for example, a printer, or a data collector/concentrator, or a computer being used for data analysis.
- a non-invasive blood pressure (NIBP) measurement module 28 provides reference blood pressures for calibration and re- calibration purposes.
- Display 20, user input 24, I/O connection 26 and measurement module 28 communicate with processor 14A by way of one or more suitable interfaces 18A.
- Apparatus 10 preferably uses a similar strategy to that described above for obtaining and displaying a value representing the oxygen saturation of a subject's blood and the subject's pulse rate.
- Each of the three sensors produces a signal which can be used to derive an oxygen saturation value and a pulse rate value.
- one signal can be selected from the best pair of sensors for the purpose of obtaining an oxygen saturation value and a pulse rate value .
- the system may be set to display a best one of the oxygen saturation or pulse rate values or, in the alternative, may present an oxygen saturation value which is a blended average of the oxygen saturation or pulse rate values derived from the signals originating from each sensor.
- system 10 has at least one redundant sensor. If any one sensor becomes disconnected or malfunctions then the signal performance of all parameter values which are calculated based upon a signal from that sensor will be poor or useless. Such values will be given either a very small weighting or no weighting at all in the computation of the parameter to be displayed.
- processor 14 causes apparatus 10 to generate a visual or audible warning if the performance criterion for one group of sensors is lower than a threshold value. Most preferably the visual or audible warning is generated if the performance criterion remains below the threshold value for longer than a predetermined time period.
- re-calibrate system 10 it is preferable to re-calibrate system 10 relatively frequently. For example, it is preferable to compare the blood pressure values produced by system 10 to a calibration value obtained by another measurement technique approximately every 30 minutes. Re-calibration is especially important if a sensor is relocated. Re-calibration is also desirable if the extremities of the subject where sensors are located are moved in relation to the subject's heart. For example, if a sensor is on a subject's finger and the arm to which the finger is attached is elevated then it would be preferable to re-calibrate the system after the subject has assumed a comfortable position with the arm elevated. Similarly, if a vasoactive medication is administered to the subject, or the dose of a continuously delivered vasoactive medication is altered, re-calibration is desirable.
- FIG. 3 illustrates apparatus 10A according to an alternative embodiment of the invention.
- Apparatus 10A comprises a separate processor 40 for computing the performance criterion and the blood pressure determined by each pair of sensors.
- processor 40A computes the performance criterion and an estimated blood pressure from the signals measured by sensors 12A and 12B.
- Processor 40B computes the performance criterion and an estimated blood pressure from the signals produced by sensors 12B and 12C.
- Sensor 40C computes the performance criterion and an estimated blood pressure from the signals produced by sensors 12A and 12C.
- Each of processors 40 also computes values for oxygen saturation for one of the sensors. The results of the computations by the processors 40 are delivered to a host processor 42.
- Host processor 42 coordinates the operation of apparatus 10A and also computes an appropriate value for the systolic and diastolic blood pressures, pulse rate, blood volume and oxygen saturation from the received signals. In doing so, processor 42 may implement the functions of selection system 16 which is described above.
- the number of sensors may be varied. If four sensors are used then there are potentially six " pairs of sensors from which pulse transit time information for blood pressure estimation may be derived. There are four sensors from which pulse and oxygen saturation information may be derived.
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Heart & Thoracic Surgery (AREA)
- Molecular Biology (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Biomedical Technology (AREA)
- Computer Networks & Wireless Communication (AREA)
- Medical Informatics (AREA)
- Physics & Mathematics (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
- Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA 2353779 CA2353779A1 (en) | 2001-07-25 | 2001-07-25 | Apparatus having redundant sensors for continuous monitoring of vital signs and related methods |
CA2353779 | 2001-07-25 | ||
PCT/CA2002/000988 WO2003009754A1 (en) | 2001-07-25 | 2002-06-28 | Apparatus having redundant sensors for continuous monitoring of vital signs and related methods |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1408826A1 true EP1408826A1 (en) | 2004-04-21 |
Family
ID=4169557
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP02742609A Withdrawn EP1408826A1 (en) | 2001-07-25 | 2002-06-28 | Apparatus having redundant sensors for continuous monitoring of vital signs and related methods |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1408826A1 (en) |
CA (1) | CA2353779A1 (en) |
WO (1) | WO2003009754A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TWI279223B (en) * | 2002-12-02 | 2007-04-21 | Giga Byte Tech Co Ltd | Motherboard with health evaluation function and its health evaluation system |
US8986207B2 (en) * | 2009-11-12 | 2015-03-24 | Covidien Lp | Systems and methods for providing sensor arrays for detecting physiological characteristics |
GB2546775A (en) * | 2016-01-28 | 2017-08-02 | Metix Ltd | Vital signs measurement apparatus |
GB2546774A (en) * | 2016-01-28 | 2017-08-02 | Metix Ltd | Vital signs monitor |
CN106725394A (en) * | 2016-12-30 | 2017-05-31 | 北京工业大学 | A kind of blood pressure data harvester and method |
EP4202532A4 (en) * | 2020-12-23 | 2024-04-24 | Samsung Electronics Co Ltd | Electronic apparatus including sensor array, and control method therefor |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0443267A1 (en) * | 1990-02-23 | 1991-08-28 | Sentinel Monitoring, Inc. | Method and apparatus for continuous non-invasive blood pressure monitoring |
JP3178195B2 (en) * | 1993-11-15 | 2001-06-18 | オムロン株式会社 | Continuous blood pressure monitor |
AU3759795A (en) * | 1994-10-13 | 1996-05-06 | Vital Insite, Inc. | Automatically activated blood pressure measurement device |
JP2000107141A (en) * | 1998-10-05 | 2000-04-18 | Denso Corp | Hemomanometer |
EP1251775A1 (en) * | 2000-01-26 | 2002-10-30 | VSM Medtech Ltd. | Continuous blood pressure monitoring method and apparatus |
-
2001
- 2001-07-25 CA CA 2353779 patent/CA2353779A1/en not_active Abandoned
-
2002
- 2002-06-28 WO PCT/CA2002/000988 patent/WO2003009754A1/en not_active Application Discontinuation
- 2002-06-28 EP EP02742609A patent/EP1408826A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
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See references of WO03009754A1 * |
Also Published As
Publication number | Publication date |
---|---|
CA2353779A1 (en) | 2003-01-25 |
WO2003009754A1 (en) | 2003-02-06 |
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Legal Events
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: SUN, MING Inventor name: SETHI, RAKESH, KUMAR Inventor name: CHEN, YUNQUAN Inventor name: LI, LUYA |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: VSM MEDTECH DEVICES INC. |
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Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20060103 |