JP2011521678A - Doppler motion sensor device and method of use thereof - Google Patents

Abstract

  An apparatus and method for sensing the characteristics of a blood vessel and the fluid carried therein.

Description

Disclosure details

[Cross-reference of related applications]
This application is based on US patent application Ser. No. 12 / 119,315 named “OPTICAL SENSOR APPARATUS AND METHOD OF USING SAME” and US Patent Application No. 12/119 named “DOPPLER MOTION SENSOR APPARATUS AND METHOD OF USING SAME”. No. 119,339, US Patent Application No. 12 / 119,325 named “INTEGRATED HEART MONITORING DEVICE AND METHOD OF USING SAME”, US Patent Application No. 12 entitled “METHOD AND SYSTEM FOR MONITORING A HEALTH CONDITION” / 119,462 (all filed on May 12, 2008) and US Patent Application No. 12 / 206,885 (September 9, 2008) named “DOPPLER MOTION SENSOR APPARATUS AND METHOD OF USING SAME” Application) (these are all by the same inventor as the present invention) and all applications are incorporated herein by reference in their entirety.

[Field of application]
The present invention relates to a sensing device, and more particularly to a sensing device for sensing fluid velocity.

〔background〕
For medical reasons, the patient's in vivo parameters may need to be monitored over a period of time. Cardiac arrhythmias are changes in the normal sequence of electrical impulses that cause the heart to pump blood systemically. Continuous monitoring may be required to detect arrhythmias. This is because abnormal heart impulse changes may only occur sporadically. With continuous monitoring, medical personnel can characterize the condition of the heart and establish an appropriate course of treatment.

  One prior art device for measuring heart rate is the “Reveal” monitor by Medtronic (Minneapolis, MN, USA). This device includes, for example, an implantable heart monitor that is used in determining whether a patient's fainting (falling) is associated with a heartbeat problem. The Reveal monitor continuously monitors heart rate and heartbeat for up to 14 months. After waking up from the onset of symptoms, the patient places the recording device outside the skin on the implanted Reveal monitor and pushes a button to transfer data from the monitor to the recording device. A recording device is provided to the doctor, who analyzes the information stored in the recording device to determine if an abnormal heartbeat is recorded. The use of the recording device is neither automatic nor autonomic and therefore requires patient awareness or another human intervention to transfer information from the monitor to the recording device.

  Another known type of implantable monitoring device is a transponder-type device in which the transponder is implanted in a patient and subsequently accessed non-invasively with a handheld electromagnetic reader. An example of the latter type of device is described in US Pat. No. 5,833,603.

〔Overview〕
In a first exemplary embodiment, a sensing device is provided for acquiring signals and calculating measurements. The sensing device is a sensor that includes one or more transducers that transmit acoustic energy, receive acoustic energy, and convert the received acoustic energy into one or more signals, the one or more transducers Includes a sensor facing one side of a blood vessel, a calculation device that operates one or more transducers to process one or more signals to obtain measurements, and a housing that surrounds the sensor and the calculation device. Including.

  In a variation of the first embodiment, the calculation device includes an algorithm that calculates a parameter value of the fluid carried by the blood vessel. In one example, the parameter is fluid velocity. In another example thereof, the fluid is blood and the parameter value is blood velocity.

  In another variation of the first embodiment, the sensing device further includes a communication device that transmits and receives communication signals. In the example, the communication signal includes at least one of a relative position value indicating the position of the blood vessel and an alarm. In one example, the communication device includes a connector configured to be operably coupled to one or more of the docking station, the second sensing device, and the energy source.

  In a further variation of the first embodiment, the housing is configured to be implanted subcutaneously.

  In yet another variation of the first embodiment, each of the one or more transducers includes a linear array of transducer segments. In one example, the transducer segment is selectively activated to transmit and receive acoustic energy.

  In another variation of the first embodiment, at least one of the one or more transducers is at a frequency different from the frequency of the acoustic energy transmitted by another of the one or more transducers, Transmits acoustic energy.

  In a further variation of the first embodiment, the one or more transducers are positioned at an angle relative to each other.

  In a variation of the first embodiment, the sensing device is approximately the same size as two 25 cent coins stacked.

  In another variation of the first embodiment, the device further includes an energy storage device. In one example, the energy storage device includes an energy coupler that receives energy to recharge the energy storage device.

  In a further variation of the first embodiment, each transducer includes an acoustic energy source, the transducer having a window through which acoustic energy passes, the acoustic energy source preventing and passing adjacent acoustic energy. Partly surrounded by a material that prevents interference between the transducers.

  In yet a further variation of the first embodiment, the sensing device further includes a second transducer oriented at an angle greater than zero with respect to the first transducer. In one example, the first and second transducers transmit acoustic energy through the first window and the second window, respectively, and the first window is between the first transducer and the second transducer. Is at least partially surrounded by a blocking material that reduces acoustic interference. In another example, the first transducer and the second transducer transmit acoustic energy at different frequencies.

  In another variation of the first embodiment, the blood parameter includes blood velocity. In one example, the sensing device further includes an optical sensor configured to transmit and receive a plurality of optical signals, and the computing device is configured to determine a diameter of the blood vessel and a vessel facing the blood vessel based on the optical signal. the distance to the facing wall), and the calculation device further calculates blood pressure based on the blood velocity, diameter, and distance.

  In a further variation of the first embodiment, the sensing device further includes a communication device that transmits and receives communication signals. In one example, the communication signal includes a distance. In another example, the calculation device further calculates blood pressure based on the blood velocity and diameter. In yet another example, the communication signal includes an alarm.

  In yet another variation of the first embodiment, the computing device diagnoses a condition using blood parameters and performs a function in response to the condition. In one example, the function is to transmit at least one of transmitting an alarm, initiating therapy, delivering an electric shock, delivering a drug, and continuously communicating data with a communication device. Including.

  In a further variation of the first embodiment, the sensing device 1 includes a connector configured to operably couple to one or more of a docking station, a second sensing device, and an energy source. In another variation, the housing is configured to be implanted subcutaneously. In yet another variation, the sensing device is approximately the same size as two stacked 25 cent coins. In still further variations, the sensing device further includes an energy storage device and an energy coupler that receives energy to recharge the energy storage device.

  In a second exemplary embodiment, a method for acquiring a signal and transmitting data is provided. The method includes providing a sensing device, the sensing device comprising one or more transducers that transmit acoustic energy, receive acoustic energy, and convert the acoustic energy into one or more signals. A calculation device, and a sensor and a calculation, which are directed to one side of a blood vessel, operate one or more transducers, one or more transducers, process one or more signals to obtain measurements Including a housing surrounding the device; transmitting acoustic energy from the one or more transducers; receiving acoustic energy from the one or more transducers to obtain one or more signals; Processing one or more signals to obtain measurements and parameters indicating the properties of the fluid. And a step of analyzing the measurements to obtain over data value.

  In a variation of the second embodiment, the sensing device further includes a sensor remote from the blood vessel, the sensor including one or more transducers, at least one of the transducers being oriented in a different direction. Two transducer portions, at least one of which is oriented at an angle of at most about 20 ° relative to the longitudinal axis of the blood vessel when measured where acoustic energy strikes the blood vessel.

  In a variation of the second embodiment, the fluid is blood and the parameter is one of blood pressure and blood velocity.

  In another variation of the second embodiment, the method further includes obtaining a relative position value and storing the relative position value in a memory. In one example, the obtaining step includes receiving a relative position value from the communication device and storing the relative position value in a memory. In another example thereof, the sensing device includes a light sensor, and the obtaining step includes receiving relative position information from the light sensor and converting the relative position information into a relative position value.

  In yet another variation of the second embodiment, the method further includes diagnosing a condition using the parameter value and performing a function in response to the diagnosing step. In one example, the function includes at least one of transmitting an alarm, initiating treatment, applying an electric shock, delivering a medication, and continuously communicating data with a communication device. Including.

  In a further variation of the second embodiment, the receiving step includes continuously obtaining signals from at least some of the one or more transducers to calculate the parameter value.

  In another variation of the second embodiment, each of the one or more transducers includes a linear array of transducer segments. In one example, the method further includes selecting one or more transducer segments and preventing transmission and reception of acoustic energy by the unselected transducer segments. In one example, selecting includes determining an incident angle of acoustic energy relative to the direction of fluid flow, and selecting a transducer segment when the incident angle is less than or equal to 20 °. In another example, the sensing device further includes an optical sensor, and the selecting step includes identifying any transducer segment with the optical sensor that blocks the transmitted acoustic energy and selecting an uninterrupted transducer segment. And including.

  In a third exemplary embodiment, an apparatus for acoustically measuring characteristics of at least one of a blood vessel and blood flowing through the blood vessel is provided. The apparatus includes a housing having a first side and a second side, and a sensor assembly attached to the housing, wherein acoustic energy is transmitted through the first side of the housing and acoustic through the first side of the housing. A sensor assembly including one or more transducers that receive energy and convert acoustic energy into a signal and are configured to operate one or more transducers and interpret the signals to determine characteristics And a calculated device.

  In a variation of the third exemplary embodiment, the one or more transducers include a first transducer that includes two transducer portions, the two transducer portions being in different directions toward the blood vessel. Directed and one of the two transducer portions is oriented at an angle of at most about 20 ° relative to the longitudinal axis of the blood vessel when measured where the acoustic energy strikes the blood vessel.

  In a variation of the third exemplary embodiment, the sensor assembly includes an acoustic energy blocking material and includes a window that transmits and receives acoustic energy.

  In a variation of the third exemplary embodiment, the housing is made of an acoustic energy blocking material and includes a window that transmits and receives acoustic energy.

  In a fourth exemplary embodiment, a system for acquiring a signal and calculating a measurement value is provided. The system is a sensor that includes a cardiac device implanted in a patient and one or more transducers that transmit acoustic energy, receive acoustic energy, and convert the received acoustic energy into one or more signals. The one or more transducers face one side of the blood vessel, operate the sensor, the one or more transducers, process one or more signals, and either one of the veins or arteries A calculation device for obtaining a blood velocity value of blood flowing through the blood vessel including the sensor, and a housing surrounding the sensor and the calculation device.

  In a variation of the fourth exemplary embodiment, the system further includes a communication device that transmits and receives communication signals based on one or more signals obtained from one or more transducers.

  In another variation of the fourth exemplary embodiment, the heart device is encapsulated inside the housing.

  In a further variation of the fourth exemplary embodiment, the sensor and computing device are operably coupled to a cardiac device positioned outside the housing.

  In yet another variation of the fourth exemplary embodiment, the transducer segment is selectively actuated to transmit and receive acoustic energy.

  In a fifth exemplary embodiment, a sensing device configured to measure blood pressure is provided. The sensing device is a Doppler sensor having a plurality of transducers that emit source waves and detect reflected waves, the Doppler sensor having an associated reference location, a reference location and a blood vessel. An optical sensor comprising a plurality of emitters and a plurality of detectors that generate a plurality of signals representative of a first distance between a neighboring wall and a second distance between a reference location and a remote wall of the blood vessel; For each of the plurality of pressure calculation results, to determine the first and second distances to calculate the area of the blood vessel, and to determine a segment of the transducer that detects the reflected wave from the blood flowing through the blood vessel, A calculation device configured to determine the velocity of the blood, wherein the velocity and area are used to calculate blood pressure; Including.

  In another variation of the fifth exemplary embodiment, the segment of the transducer that detects the reflected wave determines the direction of blood flow and the wave falls within a range of +/− 20 ° of the direction of blood flow. The segment for detecting the reflected wave having the orientation of is selected from a plurality of transducers.

  In a further variation of the fifth exemplary embodiment, the blood pressure was calculated from multiple blood velocity measurements corresponding to each of the systolic and diastolic pressures obtained from the reflected waves detected by the transducer segments. Maximum and minimum blood velocities, and maximum and minimum diameters of the blood vessels, calculated based on first and second distance measurements taken at time points corresponding to systolic and diastolic pressures; Based on.

  The features of the present invention and the manner in which they are obtained will become more apparent from the following description of embodiments of the invention, taken in conjunction with the accompanying drawings, and the invention itself will be better understood. It will be.

  Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings illustrate embodiments of the present invention, the drawings are not necessarily to scale and certain features may be emphasized in order to better illustrate and explain the present invention. The illustrations set forth in this specification illustrate embodiments of the invention in several forms, and such illustration is not to be construed as limiting the scope of the invention in any way. .

[Detailed explanation]
The embodiments discussed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments have been chosen and described so that others skilled in the art can utilize their teachings.

  FIG. 1A shows a sensing device 1 according to an exemplary embodiment. The sensing device 1 generally includes a plurality of components including a Doppler sensor 60, a calculation device 20, a communication device 30, and an energy storage device 40, each of which is attached to a board 80 and is Electronic communication. The component is surrounded by a housing 90. In one embodiment, the energy storage device 40 is configured to receive electromagnetic energy waves 44 from an external energy source 46.

  In one embodiment, the sensing device 1 is configured to determine a patient's physiological state. “Patient” means a human or animal whose physiological state is measured by the sensing device 1. Although the invention disclosed herein is described in a medical context, the teachings disclosed herein are equally applicable in other situations where a small data acquisition assembly is desirable for taking measurements over time. Is possible. For example, sensor assemblies may be desirable in submerged or difficult to reach applications, hazardous environments, applications with weight and size restrictions, fieldwork activities, and the like.

  In one embodiment, the sensing device 1 is implanted subcutaneously in the patient's body. However, it should be understood that the sensing device 1 can be implanted at different locations using various implantation techniques. For example, the sensing device 1 may be implanted in the thoracic cavity under the thorax. The housing 90 may be formed in the shape of a circular or elliptical disc, and the dimensions are approximately the same as two 25 cent coins stacked. Of course, the housing 90 may be configured in a variety of other shapes, depending on the application. The housing can include four outwardly projecting loops 92, shown in FIGS. 1B and 1C, for receiving sutures to secure the assembly subcutaneously within the patient's body. More or fewer loops 92 may be provided depending on the shape of the housing 90. When so fixed, the Doppler sensor 60 is positioned facing inward, while the energy coupler, described in detail below, faces outward.

  In another embodiment of the sensing device 1, the Doppler sensor 60 and other features of the sensing device 1 are implantable, such as pacemakers, cardiac resynchronization therapy (CRT) devices, implantable defibrillators (ICDs), etc. Integrated with heart device. In one embodiment, this integration may be achieved by combining a sensing device component with a cardiac device. If the cardiac device includes a computing device, for example, an algorithm for performing the method may be combined with the computing device of the cardiac device instead of adding a second computing device. Similarly, energy storage devices and communication devices may be combined to prevent duplication. In one embodiment, some components of the sensing device are included within the housing, and some components are included with the heart device. The heart device and components within the housing are operably connected.

  In another embodiment, the sensing device 1 is positioned outside the patient's body. A support member is provided to support the sensing device 1 outside the body. The support member can be permanently or temporarily connected to the sensing device 1. In one embodiment, the support member includes an adhesive layer that adhesively connects the support member to the patient's body. In another embodiment, the support member includes a belt that may be elastic to hold the sensing device 1 against the patient's body.

  The sensing device 1 can be implanted subcutaneously or positioned on a patient with the aid of an external mapping system such as an ultrasound device. By appropriately installing, the target blood vessel is surely positioned within the sensing range of the sensing device 1. If the blood vessel of interest is the aorta, the sensing device 1 is positioned on the patient's chest or back at a location that reduces the interference caused by the ribs of the measurements obtained by the methods described herein. Good.

1. Doppler sensor A Doppler sensor includes one or more transducers that irradiate an object with ultrasound and receive reflected ultrasound. The target fluid velocity is determined by directing an insonifying wave of ultrasonic energy at a known angle toward the fluid, measuring the frequency shift of the reflected ultrasonic energy, and then calculating the fluid velocity. Can be determined. The Doppler frequency shift is proportional to the component of the velocity vector parallel to the high frequency irradiation wave. The fluid velocity v is determined by the following equation:
v = f _d · c / (2 · f · cos θ)
Where c is the speed of sound in the blood, f is the frequency of the high frequency irradiation wave, θ is the angle between the wave and the velocity vector, and f _d is the Doppler frequency shift. Embodiments of a method for calculating blood pressure based on velocity measurements are described in sufficient detail below with respect to FIGS.

  A transducer is a device that converts acoustic energy into electrical signals and converts electrical signals into acoustic energy. The frequency shift can be calculated by various methods depending on how the transducer is operated. In one method of operation, the Doppler sensor may be a continuous wave sensor. A continuous wave Doppler sensor includes a transducer that transmits ultrasound and a transducer that receives ultrasound. The frequency shift in this method is measured directly by comparing the two waves. In another method, a pulsed wave Doppler sensor can be used. The pulse wave Doppler sensor has a single transducer that transmits and receives ultrasound. After transmitting the wave, the Doppler sensor switches from the transmission operation mode to the reception operation mode. The frequency shift is measured by comparing the phase shift between subsequently received waves. Multiple waves transmitted and received in succession are necessary for the calculation of the phase shift. Well-known algorithms such as Kasai or cross-correlation algorithms can be used to obtain the phase shift between the received pulse and the transmitted pulse.

  Transducers can include coils, piezoelectric materials, and other suitable transducers. The transducer may be focused to transmit a narrow wave or beam of acoustic energy. The transducer can also transmit wide waves of acoustic energy, ie unfocused waves. Two or more transducers may be combined in a linear array to transmit sound waves that can irradiate a large area with a desired amount of energy. The term “large” means a region larger than a region where ultrasonic waves can be irradiated with a single transducer. The linear arrays may be connected so that they can be driven as if they comprise a single transducer. The linear array may be connected so that each transducer segment operates as a separate transducer.

  FIG. 2 shows the relationship between the blood vessel 3 carrying the blood 4 having hemoglobin in the red blood cells 5 and the Doppler sensor 60. The Doppler sensor 60 has a transducer 61 positioned towards the fluid 4 carried by the blood vessel 3. The wave 62 transmitted by the transducer 61 is shown traveling along the direction indicated by the center line 63 perpendicular to the surface of the transducer 61. An arrow 6 indicates the direction of the flow of the fluid 4 in the blood vessel 3. Although the Doppler sensor 60 is described herein to illustrate its function in the sensing assembly 1, other Doppler sensors described herein may perform the same function and are generally described in this patent. Reference to Doppler sensor 60 in the application and related patent applications is equally applicable to the other Doppler sensors described herein.

  In one embodiment, a driver device, such as a pulse generator, provides an output corresponding to the desired frequency. This output can be integrated with the calculation device 20 or amplified by an amplifier such as a transistor provided outside the calculation device 20. The output can include a waveform. The calculation device 20 can provide a frequency generation function. In an alternative embodiment, the driver device provides a voltage corresponding to the desired ultrasound frequency to the transducer, which converts the electrical energy into acoustic energy in the form of ultrasound.

  In one embodiment, the sensing device 1 has a communication port that is connected to and exchanges information with other devices. A connector 85 is shown. The operation of the connector 85 connected to the other components of the sensing device 1 will be described in further detail below with reference to FIG.

  FIG. 3 shows the reflected ultrasound 64. The wave 64 is shown traveling along the direction indicated by the center line 63. The wave 64 travels in the opposite direction to the wave 62. The wave 64 also has a frequency that is different from the frequency of the wave 62. The difference is determined by selecting a transducer. In one embodiment, wave 62 is a continuous wave and wave 64 is reflected simultaneously with wave 62. In another embodiment, wave 62 is a pulse wave transmitted by transducer A before reflected wave 64 reaches transducer A. The computing device 20 can direct the transducer A to transmit the wave 62 and measure the time required for the wave 64 to reach the transmitting device A. The waves travel through soft tissue at a known constant velocity. The distance from transducer A to blood vessel 3 along center line 63 can be calculated from the travel time between transmission of wave 62 and reception of wave 64.

  FIG. 4 shows a Doppler sensor 70 that includes linear array transducers A, B, and C. FIG. The Doppler sensor 70 can be coupled or integrated with other components of the sensing device 1. Each of the transducers A, B and C is operatively connected to a driver device (not shown) that powers each transducer, and each transducer has ultrasonic waves that can travel a distance to the target fluid. When it reaches the fluid, it reflects the phase-shifted wave. Transducers A, B, and C can each be driven at a different frequency to identify the source of the reflected wave received by Doppler sensor 70. For convenience, each transducer of the linear array is referred to herein as a transducer segment. In the illustrated embodiment, each linear array transducer includes five transducer segments. The transducer segments can be operably connected to be operated separately or simultaneously. Separate actuation of one or more transducer segments is desirable to limit power consumption. More than one transducer segment may be actuated simultaneously to widen the transmission wave range. Of course, once all segments of the linear array are activated, the linear array operates as a single transducer. The Doppler sensor 70 can include three such transducers.

  Transducers A, B and C are arranged at an angle relative to each other. In one embodiment shown in FIG. 4, transducers B and C are arranged at an angle of 45 ° with respect to transducer A and 90 ° with respect to each other. Transducers may be positioned at different angles with respect to other transducers. The position and angle are selected to direct the acoustic energy in a direction that optimally reflects the acoustic energy from the blood vessel. The selection is based at least in part on the patient's anatomy. The patient's anatomy can determine where to place the sensing device 1, eg, laterally or implanted, positioned in front or back, depending on the position of the sensing device 1 from the Doppler sensor. The distance to the target vessel is determined. In one embodiment, transducers B and C are arranged at an angle of 30 ° with respect to transducer A and at an angle of 120 ° with respect to each other.

  Transducer A includes segments A1-A5, transducer B includes segments B1-B5, and transducer C includes segments C1-C5. Each segment can transmit and receive ultrasonic energy in the form of waves. Arrows that occur at each segment and project perpendicular to the segment represent the direction of the waves transmitted by each segment. In addition, arrows 72, 74 and 76 generally represent the direction of the waves produced by transducers A, B and C, respectively. The frequency of the acoustic energy is selected as a function of the distance between the transducer and the target fluid. The transducer is energized at frequencies in the range of 2-10 MHz and can reach blood vessels carrying blood at distances generally in the range of 3-20 cm after passing through the patient's soft tissue. In one embodiment, transducers A, B, and C are each energized at a frequency in the range of 2-10 MHz. In another embodiment, one or more segments of transducer A are energized at a frequency of 5 MHz, one or more segments of transducer B are energized at a frequency of 4.5 MHz, One or more segments of transducer C are energized at a frequency of 5.5 MHz. The reflected wave can be measured at each segment of the linear array transducer. Each segment may be energized sequentially and may be energized multiple times. In other embodiments, more or fewer than five segments can be used to form a transducer unit. In one embodiment, 10-15 segments are used.

The Doppler shift or frequency shift is proportional to the velocity vector component parallel to the collision wave. Since the Doppler shift depends on the cosine of the angle θ between the wave and the velocity vector, and the cosine function ranges from 0 to 1, the signal generated by the wave directed parallel to the velocity vector is Generate an optimal signal. In one embodiment, the calculation device 20 generates a signal only from a wave whose angle θ = θ ₁ is 20 ° or less. FIG. 5 conceptually illustrates the relationship between the velocity vector 6 and the waves having directions 72, 74 and 76 previously shown in FIG. FIG. 5 also shows four arrows arranged at an angle θ ₁ with respect to the velocity vector 6. Arrow 74, theta ₁ is less than, the place which forms an angle with respect to the velocity vector 6 shown. Thus, a wave directed in the direction represented by arrow 74, in this case the wave generated by linear array transducer B, can generate a usable signal. In contrast, waves directed in the direction represented by arrows 72 and 76, corresponding to transducers A and C, do not produce usable signals.

  In one embodiment, the sensing device 1 includes a light sensor assembly configured to detect the position and diameter of a blood vessel. The sensing device 1 determines which transducer does not produce a usable signal based on the position of the blood vessel and which transducers can produce a usable signal in order to save energy. It can be determined whether only sound waves are transmitted.

  To expand the range of the Doppler sensor, additional transducers may be provided at different angles, one or more of the transducers being directed at an angle of 20 ° or less with respect to the velocity vector. May be positioned at an angle that produces In one embodiment, the Doppler sensor 70 obtains a sufficient number of signals even if the relative positions of the Doppler sensor 70 and the blood vessel 3 change slightly over time or due to other factors such as the patient's activity level and posture The three transducers are arranged in a K shape so that they can. The reflected wave generated by one transducer can be received by more than one transducer. However, since the wave has a frequency corresponding to each transmission transducer, the Doppler sensor 70 can selectively filter the signal based on the relative position of the corresponding transmission transducer and its transmission frequency. Shifts can be properly identified. The frequency shift corresponds to the velocity as well as the direction of flow.

  In one embodiment, the signals from the waves received by the segments of linear array transducers A, B, and C are removed when the waves strike a blood vessel other than the blood vessel of interest. The location of the blood vessel other than the target blood vessel can be obtained by the same method as the relative position data described below. In another embodiment, the computing device 20 first determines the angle θ for each segment and only applies to the segments of transducers A, B and C if the angle θ of a segment can produce a usable signal. Selectively energize, thereby saving energy. In addition, if all segments of the transducer can generate usable signals, the computing device 20 may limit the number of signals generated to save energy. For example, if all five segments are positioned to produce a usable signal, computing device 20 selects three signals and saves 40% of the energy required to produce the five signals. can do.

  When multiple transducers, including coils, are positioned in close proximity, each transducer may interfere with the operation of the other transducer. Interference can be canceled by a suitable filter algorithm. However, filtering in this way requires additional memory and energy to process the algorithm. 6A-6D illustrate a Doppler sensor 170 configured to minimize interference between transducers. Doppler sensor 170 includes transducers 171, 172, and 173 having coils 176, 177, and 178, respectively. 6A, 6B, 6C, and 6D are a front view, a side view, a top view, and a perspective view of the Doppler sensor 171, respectively. Transducers 171, 172 and 173 comprise three sides indicated by symbol X, comprising a material configured to block electromagnetic waves, and symbol Y, comprising a material configured to pass electromagnetic waves. In the fourth side shown, the coils 176, 177 and 178 are surrounded. Side Y is referred to herein as an electromagnetic window. The barrier material may be any suitable material including a metal, and the non-blocking material may be any suitable material, such as plastic. The blocking material physically eliminates the interference between the coils 176, 177 and 178, thereby saving energy and reducing the required memory, further reducing the size of the sensing device 1. Transducers 171, 172 and 173 are stacked rather than placed in coplanar. Stacking the third dimension into the calculation of geometric distance, for example, the resources consumed by computational requirements to supplement the introduction are negligible. In many cases, the stacking effect is completely negligible due to its insignificant effect.

  FIG. 7 illustrates a Doppler sensor according to yet another exemplary embodiment. Doppler sensor 270 includes transducers 271-279, which can be single or linear array transducers. The transducers 271-279 are positioned in three K-shapes and provide a wider sensing range without increasing the contour of the sensing device 1 and thus without introducing stacking variables in the calculation. More or fewer transducers can be used to suit the shape of the housing and where the sensing device 1 is placed. In the illustrated embodiment, transducers 271, 274 and 277 include three K-shaped array bases. Transducers 271 and 277 are arranged at an angle of 30 ° with respect to transducer 274, each arranged at an angle of 45 ° with respect to the remaining two legs of each K-shaped array.

  As discussed above, calculating the blood velocity requires knowing the incident angle θ between the wave and the blood vessel 3. The angle of incidence and other data characterizing the relative position of the blood vessel 3 and the Doppler sensor can be obtained in various ways. Once obtained, it can be stored in memory as a reference value. In one embodiment, the relative position data may be provided to the calculation device 20 through the communication device 30 by an external device. The external device can wirelessly transmit a communication signal to the communication device 30 that stores the relative position data. In another embodiment, the relative position data can be provided to the computing device 20 through the communication device 30 by another implantation device. Other implantable devices include, but are not limited to, pacemakers, cardiac resynchronization therapy (CRT) devices, implantable cardioverter defibrillators (ICDs), and the like. In yet another embodiment, the relative position data may be provided to the computing device 20 by another sensor or sensor assembly included in the sensing device 1. A sensor assembly for detecting the relative position of a blood vessel is provided in the above referenced Optical Sensor application. Once the selected signal is determined, the calculation device 20 calculates the blood velocity value by comparing the frequency of the transmitted wave and the received wave according to a well-known frequency shift and angle algorithm or table.

  In another embodiment of the sensing device 1, the Doppler sensor and other features of the sensing device 1 are implantable cardiac devices such as pacemakers, cardiac resynchronization therapy (CRT) devices, implantable cardioverter defibrillators (ICDs), etc. Integrated with.

  The sensing device 1 may be programmed to perform blood rate measurements relatively infrequently (eg, once or twice a day) to conserve power, but battery technology is improved so that power It should be understood that savings is less of an issue and measurements can be made more frequently. Further, if the sensing device 1 is not implanted (ie, worn externally by the patient), power may be provided to the sensing device 1 through the connector 85, thereby necessitating power savings and use. Eliminates frequent and even continuous measurements.

2. Calculation device The calculation device 20 includes a plurality of components. Although these components are described herein as if they were separate components, the components may be combined into a single device, such as an application specific integrated circuit. The computing device 20 includes a processor, memory, one or more programs, inputs, and outputs. Memory may include, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technology. The processor and memory may be built in an integrated circuit. The integrated circuit may include one or more of Doppler sensors 60, 70, 170 and 270, and communication device 30. Furthermore, the calculation device 20 may include an A / D and / or D / A converter on the integrated circuit. Alternatively, an A / D and / or D / A converter may be provided separately.

  A program represents computer instructions that instruct a processor to perform a task in response to data. The program exists in memory. Data including reference data and measurement data is also present in the memory. The reference data may be stored in ROM in response to external input or in response to characteristics of measurement data collected over time, or may be stored in RAM so that it can be changed over time. A protocol that responds to the measurement may also be provided. The protocol may be stored in persistent memory or may be stored in non-persistent memory such as RAM.

  The calculation device 20 controls the Doppler sensor 60, 70, 170 or 270 and the communication device 30 through input and output. The computing device 20 can control the number, frequency, power level, and transmission of the waves with the Doppler sensor 60, 70, 170 or 270 to obtain the desired measurement using the minimum amount of energy.

  FIG. 8 discloses a system 300 for exchanging information with the sensing device 1. The system 300 includes a sensing device 1 that optionally has a connector 85 (shown in FIG. 1A). System 300 may also include a computer 302, a docking station 304 operably coupled to computer 302 by cable 303, and a telephone 306. In one embodiment, system 300 sends and receives communication signals 312 wirelessly to / from sensing device 1 based on processing performed by computing device 20.

  Connector 85 is configured to be plugged into docking station 304. A sensing device 1 docked on a docking station 304 is shown. While docked, the sensing device 1 can charge the energy storage device 40. The docking station 304 is operably coupled to the computer 302 to update programs and reference values stored in the memory of the computing device 20 prior to placing the sensing device 1 on or in the patient. In another embodiment, the sensing device 2 is positioned external to the patient and the connector 85 is operatively coupled to an energy source to provide power to the sensing device 2 and prevent the energy storage device 40 from being depleted.

  In further embodiments, additional sensors and devices can be coupled to sensing device 1 through connector 85. Other sensors and devices may include, but are not limited to, additional sensor assemblies 2, temperature sensors, pressure sensors, and accelerometers. Other devices may or may not include a calculation device. Other devices may also be combined with the sensing device 1 within the housing 90. An integrated sensing device is disclosed in the related Integrated Heart application referenced above. The function of the sensing device 1 may be configured to operate the additional sensors and devices by downloading a modification program configured to operate the additional sensors and devices to the memory of the computing device 20. The download may be performed while the calculation device 20 is docked in the docking station. Alternatively, a new program may be downloaded wirelessly through the calculation device 40.

  FIG. 9 is a flowchart showing a program operated in the calculation device 20 for measuring a blood parameter and performing a function corresponding to the measured value. At step 400, the computing device 20 obtains a transducer signal representative of fluid velocity from the Doppler sensor. In one embodiment, the transducer signal includes a voltage and a frequency. It should be understood that the velocity signal originates from a wave generated by a reflective object. In the case of blood velocity, this object is a red blood cell. It is generally understood that the velocity of red blood cells in the blood accurately represents the blood velocity.

  Process 400 may begin based on cardiac cycle data so as to determine blood velocity at a particular point in the cardiac cycle. Process 400 may also be initiated in response to an external command received through communication device 30 or as a result of detection of an abnormal condition by sensing device 1. Transducers A, B and C are each energized continuously. In one embodiment, transducer A transmits a wave and then switches to receive mode. The Doppler sensor 70 detects the reflected wave by a method determined by the configuration of the transducer A. Transducers B and C are in turn operated in the same way. In another embodiment, each transducer includes a transmission element and a receiving element, and thus the transducer can be actuated to simultaneously transmit and receive acoustic energy. The labeling of the transducers or the order in which they are energized is not important. More or fewer transducers may be utilized. The number and orientation of the transducers are selected to obtain data at an angle to the blood vessel 3 that produces sufficient data for the intended purpose.

  In step 402, the calculation device 20 processes the signal to obtain a measurement value. Processing includes removing inherent signal noise, converting the signal from analog to digital form, scaling, removing unselected waves, and adjusting the detected signal differently to Converting the signal into a measurement value may be included. In one embodiment, measurements taken during one cardiac cycle are averaged to obtain an average blood velocity. In another embodiment, high and low value measurements obtained during one cardiac cycle are averaged to obtain an average blood velocity. The ECG can be used to approximate when blood flows at maximum or minimum speed. After processing, the measured value may be stored in memory or analyzed to first determine whether the value should be retained. Steps 400 and 402 may be repeated as necessary to obtain sufficient measurements to calculate the desired parameters in accordance with the teachings provided herein. An embodiment of a method for calculating blood pressure based on velocity measurements is described in sufficient detail below with reference to FIG.

  In order to save energy, it is desirable to operate the Doppler sensor 70 only when it is fairly certain that a suitable signal is obtained. In one embodiment, a low power consumption sensor can be used to ascertain the angle of the target vessel relative to each transducer before the Doppler sensor 70 is activated. In one embodiment, the sensing device 1 includes an infrared sensor assembly 2 as specifically described in the above referenced Optical Sensor application. The sensor assembly 2 ensures that the sensing device 1 is positioned so that the wave transmitted from the Doppler sensor transducer intersects the blood velocity vector at an angle of approximately 20 ° or less. A transducer that is not properly positioned is not energized.

  In step 404, the calculation device 20 analyzes the measured value. The analysis may include calculation of parameter data based on the measured values and / or diagnosis. Parameter data refers to calculated values such as fluid velocity, cardiac output, cardiac rhythm, and the like. Diagnosis refers to comparing parameter values with reference values to detect abnormal patient conditions. A reference value is a normal or predicted value of a measured parameter for a particular patient. If an abnormal condition is detected, the calculation device 20 communicates (consumes unnecessary power) when the measurement values are collected, or the memory is full or at a predetermined transmission time. Rather than waiting to send measurements until they are reached (exposing the patient to unnecessary risks during the waiting period), an alarm can be communicated.

  Steps 400, 402 and 404 may be performed simultaneously. The devices and methods for calculating velocity described above are useful for calculating blood and other fluid velocities. The velocity calculation for a continuous fluid flow requires no further calculations. However, if the fluid flow is periodic rather than continuous, additional measurements and calculations are required to more fully characterize the flow and diagnose abnormal conditions based on flow characteristics. desirable.

  The reference value can include a target value and an acceptable variation range or limit. The reference value may also include measurements obtained from other sensors or from other devices through the communication device 30, including but not limited to relative position values.

  Parameter values can indicate an anomaly if they are outside the target reference value or range. In some embodiments, the parameter value can generate a statistical value, such as a moving average, for example, and an anomaly is detected when the statistical value of the parameter exceeds the predicted amount and differs from the baseline statistical value. If the parameter data exceeds the predetermined amount and is different from the predicted value, the calculation device 20 can start the new measurement cycle and check the parameter data before diagnosing the abnormality.

  One abnormal medical condition is cardiac arrhythmia. The calculation device 20 may be configured to perform an analysis of measured values, for example, to determine whether the heart rhythm is irregular and indicates arrhythmia.

  Further abnormal medical conditions can be detected externally or using values obtained from additional sensors. Additional sensors that may be included in the sensing device 1 are disclosed in the related Optical Sensor application, Integrated Heart application, and Health Condition application referenced above.

  In step 406, the computing device 20 transmits an alarm when an abnormal condition is detected, particularly a condition that is determined to be a serious or dangerous condition according to a defined protocol. The alarm can be used to trigger an alarm device or alert the patient to perform a therapeutic action. The therapeutic action may terminate or reduce physical activity. The alert can also provide global positioning (GPS) information to an emergency service. Referring to FIG. 6, if an abnormal condition is found to exist, it can be displayed on computer 36 and / or transmitted to the caregiver by communication device 30. The alert can include a text message or code corresponding to the condition. The computing device 20 can also initiate new measurement cycles and measurements continuously in response to detecting an abnormal condition.

  In step 408, the calculation device 20 can start treatment. The sensing device 1 can receive an external command to execute treatment in response to the alarm through the communication device 30. Optionally, based on the protocol, an abnormal condition may be used to instruct a device configured to deliver a treatment to deliver such a treatment. Treatment can include, for example, electric shock or drug delivery.

  At step 410, parameter values or other information is communicated to an external device. Step 410 may be performed simultaneously with any of the foregoing steps. The parameter value can be stored in a memory and transmitted wirelessly by the communication device 30. The communication signal from the communication device 30 is in response to an abnormal state, in response to an externally received command, each time the use of the memory exceeds a predetermined amount, or whenever it is determined that the energy storage level is low. The latter two states can be activated periodically, established to prevent data loss or energy loss as a result of memory overflow. It should also be understood that the sensing device 1 may include a communication device in addition to the communication device 30. For example, if the communication device 30 is a cellular modem, the sensing device 1 can also include a backup Bluetooth or RF communication device. Such a backup device may be desirable in situations where after several attempts it becomes clear that the cellular modem is unable to transmit information (eg due to low available power, poor network coverage, etc.). is there. In such a situation, the computing device 20 can activate the backup communication device to send information or alerts to an alternative external receiving device.

  Step 410 can be performed, for example, once an abnormal condition has been detected, so as to provide the caregiver with up-to-date information in substantially real time. Step 410 may be performed at regular intervals, such as once a day, once a week, once a month, or the like. Alternatively, or in addition to these transmissions, the computing device 20 causes the communication device 30 to transmit the requested data or information representing the requested data to the communication device 30 (eg, from a healthcare provider). Can be programmed to respond to a request for data received by.

  The communication signal is received by equipment near the patient, to alert the patient to the condition, or remotely (through the network by a health care provider, relative, or other predetermined recipient Etc.) can be received.

  The blood velocity at a given time depends on where at that time is related to the patient's cardiac cycle. The cardiac cycle has an electrical component and a flow component. The electrical component refers to radio waves that pump the heart muscle. This wave can be measured with a probe that includes an electrode that passes through and contacts the body. ECG is a good way to measure heart rhythms, especially abnormal rhythms. However, ECG is not a reliable means of measuring the heart's ability to pump.

  FIG. 10 shows an ECG graph 500 of cardiac electrical activity showing two cardiac cycles. A typical ECG consists of a P wave, a QRS complex, and a T wave. An equipotential line 502 separates the T wave and the subsequent P wave. The PR interval 504 is measured from the beginning of the P wave to the beginning of the QRS complex. This is typically 120 to 200 milliseconds long. The QRS complex is approximately 60-100 milliseconds long. The ST segment connects the QRS complex and the T wave. A typical ST segment lasts about 80 milliseconds. In one embodiment, the sensing device 1 includes an ECG sensor and an algorithm that detects T waves, QRS complexes, and P waves.

  The cardiac cycle can be obtained in various ways. In one embodiment, the cardiac cycle is provided to the computing device 20 through the communication device 30 by an external device. The external device can wirelessly transmit a communication signal to the communication device 30 that stores the cardiac cycle data. In another embodiment, cardiac cycle data can be provided to the computing device 20 through the communication device 30 by another implantable device. Other implantable devices include, but are not limited to, pacemakers, cardiac resynchronization therapy (CRT) devices, implantable cardioverter defibrillators (ICDs), and the like.

  In one embodiment, cardiac cycle data can be provided to the computing device 20 by another sensor or sensor assembly included in the sensing device 1. A sensor assembly for detecting the cardiac cycle is provided in the above referenced Optical Sensor application. In a further embodiment, cardiac cycle data can be provided to the computing device 20 by an ECG sensor. A sensor assembly including an ECG sensor is provided in the related Integrated Heart application referenced above.

  A blood flow and an embodiment of a method for characterizing blood flow to calculate blood pressure will be described with reference to FIGS. As stated earlier, blood velocity and blood flow vary as a function of the cardiac cycle. The velocity measurements measured in short succession can be used to characterize systolic and diastolic blood pressure. Systolic arterial pressure is the peak pressure in the artery that occurs around the beginning of the cardiac cycle. Diastolic arterial pressure is the lowest pressure (during the rest of the cardiac cycle). The time of systolic and diastolic pressure can be approximated to predict maximum and minimum blood velocities.

  In one embodiment of a method for calculating blood pressure, the sensing device 1 includes a plurality of velocity measurements at a time approximated to correspond to systolic pressure and an additional at a time approximated to correspond to diastolic pressure. A plurality of speed measurements. The calculation device 20 uses the calculated inner surface area of the aorta 3 for each measurement (eg determined from a diameter measurement facilitated by the optical sensor assembly 2) and the elapsed time between measurements, for incompressible fluids. Apply the simplified Bernoulli equation: PT = PS + PD, where PT is the total pressure, PS is the static pressure, PD is the dynamic pressure at a point in the flow stream, and the velocity Convert measured values into pressure measurements.

  Referring now to FIG. 11, at time T1, dynamic pressure PD1 and diameter d1 correspond to pressures determined from velocity measurements measured under maximum blood flow conditions. At time T2, PD2 corresponds to the pressure determined from velocity measurements measured under minimal blood flow conditions, and d2 is the diameter at time T2. In the case of the aorta 3, the static pressure under the maximum flow condition (PS1) (indicated by a force arrow pointing outwardly with respect to the outer wall of the aorta 3) directly corresponds to the blood pressure measurement during systole and the minimum flow condition The static pressure under (PS2) directly corresponds to the diastolic blood pressure measurement. These calculations assume a laminar flow and a uniform velocity profile across the vessel. A flow rate sample may be obtained by a signal obtained from a wave directed at the center of the vessel, and under these assumptions, as a divided velocity time integral of a Doppler curve divided by the flow period. It can be used to calculate the average speed.

  Systolic and diastolic blood pressure measurements can be derived by further calculating the total pressure (PT) of the blood flowing through the aorta 3. PT varies as a function of time. This is because the total pressure created by the heart activity changes over time. For example, when blood is being pumped into a blood vessel, the total pressure created is higher than the pressure that exists when the valve to the blood vessel is closed. In one embodiment, the total pressure is derived by calculating the change in pressure from the minimum flow condition to the maximum flow condition on the time axis. As described herein, these pressure derivations utilize simultaneous diameter (and area) measurements of blood vessels. This change or acceleration phenomenon, in conjunction with the stroke volume of the aorta 3 and the known elasticity, allows the calculation device 20 to determine the total pressure according to well-known principles in the art. Thus, at time T1, the equation PT1 = PS1 + PD1 is solved for PS1, and at time T2, the equation PT2 = PS2 + PD2 is solved for PS2. As described above, PS1 and PS2 are systolic and diastolic blood pressure measurements, respectively.

  One complication of making an accurate determination of blood pressure is the variability in the diameter of the blood vessel being measured. As blood is pumped through the blood vessel, the flexible wall of the blood vessel expands and contracts, thereby effecting blood pressure measurements. This effect is the result of changes in resistance to blood flow that occur as a function of changes in vessel diameter. One embodiment of the present disclosure takes this variability into account using the technology described herein and the following method.

  As mentioned above, blood pressure is directly related to the static pressure on the inner wall of the blood vessel under consideration. As also mentioned above, blood pressure (PS) is calculated using the total pressure (PT) of the blood vessel (ie PT = PS + PD), which is the sum of this static pressure (PS) and dynamic pressure (PD) of the blood flow. Is done. The dynamic pressure is measured directly using a Doppler sensor 70 as described herein. More specifically, PD is obtained from blood flow (velocity) measurements using a standard relationship between flow rate and pressure.

  The static pressure depends in part on the diameter of the blood vessel (a change in diameter causes a change in resistance, which affects the measured static pressure). The diameter of the blood vessel is measured in this situation using an optical sensor assembly 2 as described herein. The area of a blood vessel having a substantially circular cross section is directly calculated from the measured diameter. The sensing device 1 of the present disclosure calculates the area of the blood vessels in close increments near the minimum (Min1, Min2, Min3) and maximum (Max1, Max2, Max3) amplitudes of the patient's cardiac cycle. More specifically, as shown in FIG. 12, the time rate integral is generated by calculating a sample of the measured amount at a rate of 50 samples per second. In each sample, the method determines the area change of the blood vessel 3 (by measuring the change in diameter using the optical sensor assembly 2) and increases and decreases the velocity of the blood 4 flowing through the blood vessel 3. decide. The individual area and velocity calculations in these dense samples (10 samples C1-C10 are shown in the embedded view of the sample measured at Min1) are According to the relationship, it is possible to determine the blood flow individually. It should be understood that a similar set of ten samples C1-C10 are measured at each of the sample peaks and troughs shown in FIG. For simplicity, only one set of 10 samples is drawn with an expanded time axis.

  The diastolic and systolic blood pressure measurements correspond to the time rate integral measurements in each of the sample peaks (Max1, Max2, Max3) and valleys (Min1, Min2, Min3) shown in the graph of FIG. In one embodiment of the present disclosure, 10 samples are measured at the peak (a few milliseconds apart) and 10 samples are measured at the trough (a few milliseconds apart). These sample groups are measured for each of three consecutive pump cycles, as shown in FIG. Of course, it should be understood that more or fewer samples may be used depending on the application. The samples are then averaged (or filtered to remove out-of-range samples) to determine the flow rate of each measured sample.

The acceleration of blood from each individual sample to the next sample in the measurement sequence is determined by the well-known equation a = v ² / r, where v is the velocity of blood 4 and r is the radius of vessel 3 (Obtained from measurements made by the photosensor assembly 2 as described above). The acceleration measurements are then converted to pressure (considering area and velocity changes on the time axis) according to principles well known in the art. This pressure result represents the total pressure (PT) and takes into account the actual instantaneous diameter (area) of the blood vessel 3 for each measurement sample, thereby reducing the potential error in blood pressure caused by the flexibility of the blood vessel 3. To compensate. With PT and PD calculated for each sample as described above, PS is determined by the relationship PS = PT-PD for each sample. The resulting blood pressure measurement is in g / mm ² units and may be converted to tor units according to standard conversions (eg, 1 torr = 1.3595e-5 Kg / mm ^ 2). The final PS is reached by averaging 10 samples in the peak and averaging 10 samples in the valley. This results in three peak values and three valley values (ie, one for each of the three sampled cardiac cycles). For each period, deceleration from peak to trough is determined (over time) and acceleration from trough to the next peak is determined (over time). This results in three acceleration values and three deceleration values. Each set of three is averaged to yield a final PT for acceleration and a final PT for deceleration.

  Another aspect of the present disclosure is a method for obtaining Doppler measurements used in the aforementioned calculations. More specifically, using the measured geometry of the sensor 1 and the blood vessel 3 being sampled, the system will reject unrelated portions of the reflected wave measured by the Doppler sensor 70. Can be configured. As previously described, the waves emitted by the linear array transducer of Doppler sensor 70 move in all directions and are reflected from many different structures in the path of travel. Only the portion of the signal reflected by the blood flow being measured should be used to determine the velocity. As described below with respect to FIG. 13, the sensor 1 can isolate the transducer segments of the linear transducer array that receive this useful data.

  Referring now to FIG. 13, the distances H1 and H2 are known based on optical measurements performed by the optical sensor assembly 2, as described more fully in the referenced Optical Sensor application referenced above. It is. More specifically, since the size of the sensor 1 and the location of the center of the Doppler sensor 70 are known, the distance from the center of the Doppler sensor 70 to each edge of the blood vessel 3 is determined by the optical sensor set described herein. Using the measurements provided by the solid 2, it can be calculated. In this example, the portion of transducer 70B of Doppler sensor 70 that provides relevant velocity information is determined. The length of the transducer 70B is represented by the designation X1 and is known because the transducer 70B is an actual hardware component built into the sensor 1. Using the standard geometric relationship, the calculation device 20 of the sensor 1 uses the angle α to calculate the length C of the triangles H2, X1, C, which is determined by the transducers 70A, 70B, 70C. Known based on K-shaped configuration. Similarly, the angle β can be determined.

  Since H1 was also measured using photosensor assembly 2 as described above, angle β1 and length B can also be determined, resulting in all measurements of triangles H1, X1, B. As mentioned above, one limitation of Doppler technology is that the measured angle of the reflected signal must fall within +/− 20 ° of the flow direction. Sensor 1 utilizes this known property of Doppler technology to project virtual points on transducer 70B that represent the boundaries of the segments of transducer 70B that provide important information about blood velocity. More specifically, the point Xn is obtained by drawing a line at an angle of 20 ° below the side B of the triangles H1, X1, and B and calculating the intersection of the line with the transducer 70B. Similarly, the point Xm is obtained by drawing a line at an angle of 20 ° under the side C of the triangles H2, X1, and C, and calculating the intersection of the line with the transducer 70B. The segment of transducer 70B between point Xn and point Xm, and between point Xm and point Xl (which is the outer end of transducer 70B), from blood 4 gives an accurate indication of blood velocity. This is the area of the transducer that receives the reflected wave. Thus, other signals detected by other segments of transducer 70B may be ignored when calculating velocity.

  It should be understood that the blood vessels being measured in the manner described above are constantly moving as a result of heart pumping and / or human physical activity. Thus, for the purpose of determining blood velocity, determining the relevant segment of transducers 70A, 70B, 70C is often done at least whenever a velocity sample is obtained in the blood pressure calculation. This data may be averaged to produce a more accurate velocity measurement.

Another aspect of the present disclosure is a method in which the curvature of blood vessel 3 is accounted for in blood pressure measurements. For each of the ten samples C1-C10 depicted in the peaks of FIG. 12, the diameter of the blood vessel 3 is measured using the optical sensor assembly 2 and the flow rate is measured using the relevant segment of the Doppler sensor 70. The Of course, the elapsed time between samples is also known. Considering the shape of the blood vessel 3 detected by the optical sensor assembly 2 as described herein, the computing device 20 calculates the portion of the Doppler signal where the relevant reflection portion is substantially straight of the blood vessel 3. Or it can be determined whether it is reflected from blood flowing through the curved portion. When the detection part of the blood vessel 3 is substantially straight, the acceleration is derived by the relationship of acceleration = (Δflow rate) / (Δtime). When the detection portion of the blood vessel 3 is curved, the acceleration equation is acceleration = v ² / r (where r is the radius of the blood vessel 3), but the equation w = (ΔΦ) / (Δtime) (where Φ is corrected by the bending angle of the blood vessel 3). The result of the equation w = (ΔΦ) / (Δtime) results in a percent correction for the acceleration equation. For example, when w = 3, the corrected acceleration equation is a == (v ² /r)*1.3. By calculating the acceleration for each of the samples shown in FIG. 12, the apparatus determines the change in acceleration / deceleration and uses this determination as described above to calculate the total pressure.

  The blood pressure calculation described above is related to determining the blood pressure of the aorta 3, but assuming that the pulmonary artery is within the sensing range of the monitoring device 1, the same process may be performed to determine the blood pressure of the pulmonary artery. You should understand what you can do. As described in the Optical Sensor application, the monitoring device 1 measures the oxygen saturation of the pulmonary artery and the aorta 3 and determines which blood vessels are carrying blood at a higher oxygen saturation. Distinguish between pulmonary artery and aorta 3. The blood vessel should be the aorta 3. In another embodiment of the present invention, the monitoring device 1 instead identifies a lower oxygen saturation vessel as the vessel of interest (ie pulmonary artery). Next, the location and size of the pulmonary artery is determined as described for the aorta 3. With the pulmonary artery geometry defined, the pressure of blood flowing through the pulmonary artery is measured as described above for the aorta 3.

3. Communication Device Referring again to FIG. 8, system 300 is configured to transmit and receive communication signals. The communication device 30 is a two-way communication device using, for example, a mobile phone system and / or a GPS satellite system. The communication device 30 includes an antenna that transmits and receives communication signals. The communication signal travels wirelessly to and from one of a plurality of optional external communication devices.

  The external communication device may be any electronic device capable of receiving communication signals wirelessly, such as the computer 302 or the telephone 306 embodied as a mobile phone. The telephone 306 may be an emergency facility switchboard or a hospital or medical center switchboard. By communication signal is meant a signal having one or more of the characteristics set or changed to encode signal information. As non-limiting examples, communication signals include acoustic media, RF media, infrared media, other wireless media, and combinations of any of the foregoing. The external communication device may also be a relay unit located outside the patient's body, for example clipped to the patient's belt. The relay unit can include a receiver that receives a transmission from the communication device 30 and a transmitter that retransmits the communication signal to another external communication device. The relay unit may also be fixed and wired so that it is connected to the Internet or directly connected to the healthcare provider's computer. Similarly, the relay unit can receive a communication signal from the healthcare provider and transmit the signal to the communication device 30.

  The communication signal from the communication device 30 can include a voice message, a text message, and / or measurement data. The communication received by the communication device 30 can include data such as updated reference data, or commands. The commands can include instructions to the computing device 20 to perform tasks such as, for example, treating a patient, collecting and transmitting additional data, or updating reference data.

4). Energy Storage Device Referring again to FIGS. 1A, 1B and 1C, a system for recharging the energy storage device 40 may be provided. The calculation device 20 receives energy from the energy storage device 40. The energy storage device 40 includes energy storage components such as a battery. Optionally, the sensing device 1 may also include an energy coupler that receives energy from an external source to charge the energy storage device 40.

  An example of an energy coupler is an electromagnetic device, such as an induction coil 42, that receives an external electromagnetic signal 44 and converts such signal to electrical energy to recharge the energy storage component. An external electromagnetic device 46 generates an electromagnetic signal 44 that is received by the energy storage device 40 and converted to electrical energy. The energy storage device 40 can provide a charging signal to the calculation device 20. The computing device 20 can compare the charge signal with a reference charge signal, initiate a low charge communication signal, and alert the patient and / or health care provider. Alternatively, a detector such as a voltage sensor may be used to monitor the charging of the energy storage device 40 and provide a signal to the computing device 20 when the charging falls below a threshold. The electromagnetic device 46 can be placed near the sensing device 1 to charge the energy storage device 40.

  Alternatively or additionally, energy may be provided in the form of ultrasonic vibrations. For example, a piezoelectric transducer may be included in the sensing device 1. The ultrasonic vibration may be given from the outside. The transducer generates electricity when driven by ultrasonic vibration.

  While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Furthermore, this application is intended to cover departures from the present disclosure that fall within known or customary practice in the art to which this invention belongs.

Embodiment
(1) In a sensing device configured to measure blood pressure,
A Doppler sensor having a plurality of transducers for emitting a source wave and detecting a reflected wave, the Doppler sensor having an associated reference location;
A plurality of emitters and a plurality of emitters for generating a plurality of signals representative of a first distance between the reference location and a nearby wall of the blood vessel and a second distance between the reference location and a remote wall of the blood vessel; A light sensor including a detector; and
For each of a plurality of pressure calculations, the first and second distances are determined to calculate the area of the blood vessel, and a transducer segment that detects reflected waves from blood flowing through the blood vessel is provided. A calculating device configured to determine and thereby determine the blood velocity, wherein the velocity and area are used to calculate blood pressure;
A housing surrounding the Doppler sensor, the light sensor, and the calculation device;
A sensing device.
(2) In a sensing device that acquires a signal and calculates a measured value,
A sensor including a first transducer for transmitting acoustic energy, receiving acoustic energy, and converting the received acoustic energy into one or more signals, wherein the first transducer is a mammal Two transducer portions oriented in different directions toward a blood-carrying blood vessel, wherein at least one of the two transducer portions is measured when the acoustic energy strikes the blood-carrying blood vessel, A sensor oriented at an angle of at most about 20 ° relative to the longitudinal axis of the blood-carrying blood vessel;
A calculation device for operating the first transducer and calculating a blood parameter based on the one or more signals;
A housing surrounding the sensor and the computing device, the housing having a wall facing the blood vessel through which the acoustic energy passes, the housing being attached to the mammal in a spaced relationship with the blood vessel A housing further comprising an attachment feature configured to:
A sensing device.
(3) In a system that acquires signals and calculates measured values,
A cardiac device implanted in the patient;
A sensor spaced from a blood vessel, the sensor comprising one or more transducers that transmit acoustic energy, receive acoustic energy, and convert the received acoustic energy into one or more signals; One or more transducers face one side of the blood vessel, and at least one of the transducers includes two transducer parts oriented in different directions, and at least one of the two transducer parts A sensor that is directed at an angle of at most about 20 ° to the longitudinal axis of the blood vessel when measured where the acoustic energy strikes the blood vessel;
A calculator for manipulating the one or more transducers and processing the one or more signals to obtain a blood velocity value of blood flowing through the blood vessel;
A housing surrounding the sensor and the calculation device;
Including the system.

FIG. 2 is a schematic side view of an exemplary embodiment of a sensing device. FIG. 2 is a view of the sensing device of FIG. 1 facing outward. It is a perspective view of the sensing device of FIG. FIG. 2 is a schematic side view of the sensing device of FIG. 1 and a blood vessel. FIG. 2 is a schematic side view of the sensing device of FIG. 1 and a blood vessel. FIG. 3 is a schematic top view of an exemplary embodiment of a Doppler sensor. A conceptual vector representation of wave and fluid flow directions. FIG. 6 is a schematic front view of a Doppler sensor according to another exemplary embodiment. 6 is a schematic side view of a Doppler sensor according to another exemplary embodiment. FIG. 6 is a schematic top view of a Doppler sensor according to another exemplary embodiment. FIG. FIG. 6 is a schematic perspective view of a Doppler sensor according to another exemplary embodiment. FIG. 6 is a schematic top view of another exemplary embodiment of a Doppler sensor. 2 is a conceptual diagram of a system configured to transmit and receive communication signals from the sensing device of FIG. 2 is a flowchart of an exemplary method for measuring motion. A schematic representation of the cardiac cycle. It is a conceptual diagram of the fluid which flows through the blood vessel. It is a graph of the measured value acquired during the cardiac cycle. 1 is a conceptual diagram of a Doppler sensor according to an exemplary embodiment. FIG.

Claims (3)

In a sensing device configured to measure blood pressure,
A Doppler sensor having a plurality of transducers for emitting a source wave and detecting a reflected wave, the Doppler sensor having an associated reference location;
A plurality of emitters and a plurality of emitters for generating a plurality of signals representative of a first distance between the reference location and a nearby wall of the blood vessel and a second distance between the reference location and a remote wall of the blood vessel; A light sensor including a detector; and
For each of a plurality of pressure calculations, the first and second distances are determined to calculate the area of the blood vessel, and a transducer segment that detects reflected waves from blood flowing through the blood vessel is provided. A calculating device configured to determine and thereby determine the blood velocity, wherein the velocity and area are used to calculate blood pressure;
A housing surrounding the Doppler sensor, the light sensor, and the calculation device;
A sensing device. In a sensing device that acquires signals and calculates measurements,
A sensor including a first transducer for transmitting acoustic energy, receiving acoustic energy, and converting the received acoustic energy into one or more signals, wherein the first transducer is a mammal Two transducer portions oriented in different directions toward a blood-carrying blood vessel, wherein at least one of the two transducer portions is measured when the acoustic energy strikes the blood-carrying blood vessel, A sensor oriented at an angle of at most about 20 ° relative to the longitudinal axis of the blood-carrying blood vessel;
A calculation device for operating the first transducer and calculating a blood parameter based on the one or more signals;
A housing surrounding the sensor and the computing device, the housing having a wall facing the blood vessel through which the acoustic energy passes, the housing being attached to the mammal in a spaced relationship with the blood vessel A housing further comprising an attachment feature configured to:
A sensing device. In a system that acquires signals and calculates measurements,
A cardiac device implanted in the patient;
A sensor spaced from a blood vessel, the sensor comprising one or more transducers that transmit acoustic energy, receive acoustic energy, and convert the received acoustic energy into one or more signals; One or more transducers face one side of the blood vessel, and at least one of the transducers includes two transducer parts oriented in different directions, and at least one of the two transducer parts A sensor that is directed at an angle of at most about 20 ° to the longitudinal axis of the blood vessel when measured where the acoustic energy strikes the blood vessel;
A calculator for manipulating the one or more transducers and processing the one or more signals to obtain a blood velocity value of blood flowing through the blood vessel;
A housing surrounding the sensor and the calculation device;
Including the system.

Images