Optical methods for measuring arterial pulsation and evaluating cardiopulmonary hemodynamics
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- DYNOCARDIA INC
- Filing Date
- 2021-08-10
- Publication Date
- 2026-06-05
Smart Images
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Abstract
Description
Background Art
[0001] This application claims the priority of U.S. Provisional Patent Application No. 63 / 063,482, "Optical Methods for Measuring Arterial Pulse," filed on August 10, 2020, which is hereby incorporated by reference in its entirety.
[0002] The measurement of cardiopulmonary parameters such as heart rate (HR), blood pressure (BP), respiratory rate (RR) and respiratory pattern, as well as other hemodynamic parameters such as cardiac output, stroke volume and peripheral vascular resistance, is known to be important in human health. In particular, the ability to identify abnormal BP patterns such as white coat hypertension, masked hypertension, non-dipping and other abnormal patterns during sleep and morning BP surges can be particularly important. If cardiopulmonary parameters can be accurately measured by non-invasive and dynamic methods, it can facilitate the accurate assessment and treatment of critically ill patients in the hospital. This accurate measurement enables physicians and other healthcare providers to more appropriately adjust treatment and / or identify lifestyle motivations for the management of hypertension and other chronic diseases that derive benefits from tight BP control such as heart failure, sleep apnea and chronic renal insufficiency. Conventional BP and hemodynamic monitoring devices suffer from accuracy problems, do not provide dynamic results over a long period of time, or are relatively invasive, all of which significantly limit the number of situations in which the device can be used. Therefore, a system adapted to monitor a patient's hemodynamic parameters by a non-invasive and dynamic method over a long period of time would be highly advantageous.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
[0004] Generally, this disclosure describes systems and methods for non-invasive estimation and continuous monitoring of cardiopulmonary parameters, particularly by directly measuring displacement of the skin surface and forces acting on superficial arteries such as the radial artery of the wrist.
[0005] In one embodiment, an optical mechanical sensor system for use with a patient, a patient-worn surface displacement system, and superficial artery A patient-wearing surface displacement system is provided, comprising a deformable surface configured to be positioned adjacent to a patient and a plurality of optical markings positioned on the deformable surface; an actuator configured to apply pressure to hold the surface displacement system toward the patient such that spatiotemporal movement of a superficial artery causes corresponding movement of the deformable surface and the plurality of optical markings; an imaging system configured to visualize the plurality of optical markings at an oblique angle; and a computer system coupled to the imaging system, the computer system comprising a processor and memory, the memory of which, when executed by the processor, the computer system receives a plurality of images of the plurality of optical markings from the imaging system, determines the spatiotemporal movement of the optical markings based on the received plurality of images, and determines cardiopulmonary parameters associated with the patient based on the determined spatiotemporal movement of the optical markings.
[0006] In another embodiment, a method for monitoring a patient's cardiopulmonary parameters using a surface displacement system, wherein the measuring device comprises a deformable surface, a plurality of optical markings placed on the deformable surface, and an actuator configured to apply pressure to hold the surface displacement system against the patient, the method comprising the steps of attaching the surface displacement system adjacent to the patient's superficial artery, and causing the actuator to apply pressure to hold the surface displacement system against the patient, as a result, superficial arteryA method is provided comprising the steps of: the spatiotemporal motion of a deformable surface causing corresponding motion of a plurality of optical markings; capturing a plurality of images of the plurality of optical markings via an imaging system oriented at an oblique angle to the optical markings; determining the spatiotemporal motion of the optical markings based on the received plurality of images via a computer system; and determining patient-associated cardiopulmonary parameters based on the determined spatiotemporal motion of the optical markings via a computer system.
[0007] In yet another embodiment, an opto-mechanical sensor system for use with a patient and an imaging system, an opto-mechanical sensor system for use with a patient, a patient-worn surface displacement system, and superficial artery A surface displacement system is provided, comprising a deformable surface configured to be positioned adjacent to a patient and relative to the patient, and a plurality of optical markings positioned on the deformable surface, wherein the plurality of optical markings are configured to be visualized at an oblique angle by an imaging system; an actuator configured to apply pressure to hold the surface displacement system relative to the patient such that the spatiotemporal movement of the superficial artery causes corresponding movement of the deformable surface and the plurality of optical markings; and a computer system coupled to the imaging system, wherein the computer system comprises a processor and memory, the memory of which, when executed by the processor, stores instructions for the computer system to receive a plurality of images of the plurality of optical markings from the imaging system, determine the spatiotemporal movement of the optical markings based on the received plurality of images, and determine cardiopulmonary parameters associated with the patient based on the determined spatiotemporal movement of the optical markings. [Brief explanation of the drawing]
[0008] The accompanying drawings incorporated herein and forming part of the specification illustrate embodiments of the present invention and, together with the written description, help to illustrate the principles, characteristics, and features of the present invention. [Figure 1A] This is a block diagram showing a non-invasive hemodynamic parameter monitoring system according to one embodiment of the present disclosure. [Figure 1B] This is another block diagram illustrating a non-invasive hemodynamic parameter monitoring system according to one embodiment of the present disclosure. [Figure 2] This figure shows a first embodiment of a non-invasive hemodynamic parameter monitoring system using a deformable gel elastomer, according to one embodiment of the present disclosure. [Figure 3] This figure shows a second embodiment of a non-invasive hemodynamic parameter monitoring system using a deformable gel elastomer, according to one embodiment of the present disclosure. [Figure 4] This figure shows a first embodiment of a non-invasive hemodynamic parameter monitoring system using a deformable surface, according to one embodiment of the present disclosure. [Figure 5] This figure shows a second embodiment of a non-invasive hemodynamic parameter monitoring system using a deformable surface, according to one embodiment of the present disclosure. [Figure 6A] This figure shows a second embodiment of a non-invasive hemodynamic parameter monitoring system using a piston, according to one embodiment of the present disclosure. [Figure 6B] This figure shows a second embodiment of a non-invasive hemodynamic parameter monitoring system using a secondary inflatable bag, according to one embodiment of the present disclosure. [Figure 7A] This is a perspective view of a measuring device according to one embodiment of the present disclosure. [Figure 7B] This is an inverse perspective view of the measuring device shown in Figure 7A, according to one embodiment of the present disclosure. [Figure 8A] This is a perspective view of a measuring device worn by an individual, according to one embodiment of the present disclosure. [Figure 8B] This is an inverse perspective view of the measuring device shown in Figure 8A, worn by an individual, according to one embodiment of the present disclosure. [Figure 9] This figure shows a coordinate system defined with respect to a deformable surface according to one embodiment of the present disclosure. [Figure 10A] This figure shows a temporary representation of the measurement embodiment shown in Figures 2 and 3, according to one embodiment of the present disclosure. [Figure 10B] This figure shows a temporary representation of the measurement embodiment shown in Figures 4 and 5, according to one embodiment of the present disclosure. [Figure 11A] This is a graph showing exemplary displacement signals at multiple locations for an embodiment of the measuring device shown in Figures 2 and 3, according to one embodiment of the present disclosure. [Figure 11B] This is a graph showing exemplary displacement signals at multiple locations for an embodiment of the measuring device shown in Figures 4 and 5, according to one embodiment of the present disclosure. [Figure 12A] This figure shows a surface map of the maximum optical marking displacement at multiple locations for an embodiment of the measuring device shown in Figures 2 and 3, according to one embodiment of the present disclosure. [Figure 12B] This figure shows a surface map of the maximum optical marking displacement at multiple locations for an embodiment of the measuring device shown in Figures 4 and 5, according to one embodiment of the present disclosure. [Modes for carrying out the invention]
[0009] Described herein is a system and method for optically measuring skin surface movement by positioning an opto-mechanical sensor array and applying counter-pressure to the skin via a large superficial artery, such as the radial artery of the wrist, in order to non-invasively evaluate arterial pulsation and its characteristics. This information can be used to generate a continuous arterial pulse waveform and measure BP, HR, RR, and other hemodynamic parameters. The intra-arterial pressure wave has a direct relationship with the force and displacement on the inner surface of the arterial wall, which affects the deformation and force applied to the opto-mechanical sensor array at specific locations on the skin surface, particularly over superficial arteries such as the radial artery.
[0010] The optical method accurately measures the pulsation of larger blood vessels and their characteristics. The HR measurement by this optical method is more reliable compared to photoplethysmography (PPG), an optical measurement method often used for heart rate monitoring purposes. PPG measures the volume fluctuations of capillary blood circulation using a light source and a photodetector on the surface of the skin. Compared to the optical method described here, the PPG signal intensity is weak and is affected by factors such as motion artifacts and environmental temperature.
[0011] In this optical method, the characteristics of the spatio-temporal pattern caused by the skin movement observed on the radial artery during arterial pulsation can be changed by varying the external counterpressure applied to the skin over the artery. Characteristics such as the shape, size, and displacement of the spatio-temporal pattern change according to the applied counterpressure and the intravascular pressure. By analyzing the spatio-temporal pattern, it is possible to continuously measure the BP described in "Patent Document 1" filed on March 29, 2019, which is hereby incorporated by reference in its entirety into this specification.
[0012] During arterial pulsation, the movement of the skin over the radial artery is mainly in a direction perpendicular to the skin surface, which can also be referred to as the z-axis. The purpose of the described system and method is to measure the movement of the skin surface over the radial artery.
[0013] Non-invasive hemodynamic parameter monitoring In this specification, a system and method are described for placing a pattern of optical markings on the surface of a skin patch connected to an artery by non-invasively adjacent soft tissues and applying a controlled amount of pressure to ensure a close interface between a deformable surface on which the optical markings are disposed and the patient's skin. The optical markings can be dots, lines, stripes, grids, or any other pattern. Once fixed at a given location, changes in the shape and force of the artery can be detected based on perturbations or movements of the optical markings caused by the mechanical pulsations of the artery during the cardiac cycle. This change corresponds to a spatio-temporal signal from the artery or adjacent soft tissues. The spatio-temporal signal can be measured and processed via a computer system or a controller to determine hemodynamic parameters.
[0014] FIG. 1A is a diagram of one embodiment of an opto-mechanical sensor system 100 according to one embodiment of the present disclosure. The opto-mechanical sensor system 100 can include an optical system 102 configured to visualize or otherwise monitor a patient device. In some embodiments, the optical system 102 can be configured to be removed around the patient's wrist such that only the patient device or a portion thereof (e.g., the surface displacement system 108) bears against the patient's skin adjacent to the radial artery, particularly at the wrist. For example, the surface displacement system 108 can be imaged via a cellular phone optical system completely detached from the patient's body or an optical system attached to a fixed surface (e.g., a physical wall) or some other portion of the body (e.g., the shoulder). The surface displacement system 108 can include one or more optical markings 106 disposed on or otherwise associated with a deformable surface 109. The deformable surface 109 can be constructed from various materials such as thermoplastic polyurethane or nylon. The thickness of the deformable surface 109 can be, for example, from 10 μm to 300 μm.
[0015] Figure 1B is a diagram of an opto-mechanical sensor system 100 according to one embodiment of the present disclosure. The opto-mechanical sensor system 100 may include an optical system 102, which includes an imaging system 104 and an illumination source 112. In some embodiments further described below, the optical system 102 may include one or more mirrors 131 and a transparent or transparent layer (e.g., a transparent plate 122, as described below) on which the imaging system 104 is configured to visualize a surface displacement system 108. In some embodiments, the optical system 102 may be configured such that a portion of the optical system 102 is attached to or adhered to the patient's wrist so as to withstand the surface displacement system 108 on the patient's skin adjacent to the radial artery, particularly at the wrist. The surface displacement system 108 may include a deformable surface 109 having optical markings 106. The optical markings may be dots, lines, stripes, grids, or any other pattern. In various embodiments, the deformable surface 109 may include a membrane, an elastomer, an air or fluid-filled bag, or any combination of these options. As described above, the deformable surface 109 can be constructed from various materials such as thermoplastic polyurethane or nylon. The thickness of the deformable surface 108 can be, for example, 10 μm to 300 μm.
[0016] The surface displacement system 108 may be configured to deform, move, or otherwise change in response to mechanical pulsations through the patient's radial artery, thereby causing the optical marking 106 to shift accordingly. The movement of the optical marking 106 can be visualized via the imaging system 104. The optic-mechanical sensor system 100 may further include a computer system 114 coupled to the optical system 104. The computer system 114 may be programmed or otherwise configured to calculate one or more cardiopulmonary parameters associated with the patient based on the detected movement of the optical marking 106 visualized via the optical system 104. In some embodiments, the optical system 102 may further include an illumination source 112, which may be configured to illuminate the optical marking 106 with visible light or electromagnetic radiation (EMR) in the invisible portion of the spectrum (e.g., infrared or ultraviolet). In some embodiments, the illumination source 112 may also be used to project the optical marking onto a deformable surface 109.
[0017] The opticmechanical sensor system 100 may further include an actuator 110 configured to apply force to the skin via a large artery (e.g., the radial artery in the wrist) to the surface displacement system 108 in order to assist in the visualization of arterial pulsations. In particular, if the interface between the surface displacement system 108 and the skin is not tightly coupled, it may negatively affect the ability of the patient's arterial pulsations to deform the surface displacement system 108, which may affect the opticmechanical system 100's ability to detect and calculate the patient's cardiac respiratory parameters. The actuator 110 may include a bounded space such as a balloon or chamber, which may be inflated by an air pump or an electric piston. In some embodiments, the actuator 110 may include a manually adjustable component such as a manual strap. In other embodiments, the actuator 110 may include an electromechanically adjustable component such as a motor configured to tighten a strap, balloon, cuff, bag, or another such component configured to apply pressure to a patient.
[0018] The computer system 114 may include hardware, software, firmware, or a combination thereof that is programmed or otherwise configured to cause the computer system 114 to perform the actions described herein. In the illustrated embodiment, the computer system 114 may further include a processor 116 and a memory 118 coupled thereto. The memory 118, when executed by the processor 116, stores instructions that cause the computer system 114 to receive images of optical markings 106 from the imaging system 104, determine the spatiotemporal motion of superficial arteries (e.g., radial arteries) based on the received images, and determine cardiopulmonary parameters thereon. For example, the computer system 114 may reconstruct arterial pulses and measure BP based on the respiratory variance of BP. In another example, the computer system 114 may measure RR and respiratory patterns and measure cardiac output, stroke volume, and other cardiopulmonary parameters based on an analysis of the BP waveform. In one embodiment, the computer system 114 may be incorporated into, or otherwise integrated with, a patient-worn device, an imaging system 104, or other components of the optic-mechanical sensor system 100. In another embodiment, the computer system 114 may be transmissibly coupled to a patient-worn device, an imaging system 104, or other components of the optic-mechanical sensor system 100. For example, the computer system 114 may be embodied as a cloud computing architecture.
[0019] In various embodiments, the optical system 104 may include individual cameras (or image sensors) or a variety of cameras (or image sensors) that can be configured to provide stereoscopic visualization of the optical markings 106. In some embodiments, the optical system 102 may be located above the actuator 110 (as in the embodiments shown in Figures 2-4) or below the actuator 110 (as in the embodiment shown in Figure 6B). In other embodiments, the optical system 10 may be located inside the actuator 110, as in the embodiment shown in Figure 5, or otherwise integrated with it. In any of these embodiments, the imaging system 104 may be positioned at an oblique angle to the surface displacement system 108, as will be described in more detail below, thereby increasing the sensitivity of surface displacement detection (Z motion) and improving the visualization of the optical markings 106.
[0020] In various embodiments, the optical marking 106 may include a variety of different colors or patterns that are visually identifiable by the imaging system 104. Furthermore, in various embodiments, the optical marking 106 may be configured to reflect or emit EMR in the visible portion of the EMR spectrum. However, the optical marking 106 may also be configured to reflect or emit EMR in other portions of the EMR spectrum, such as infrared (IR) or ultraviolet (UV). Thus, the imaging system 104 may be configured to utilize a variety of different imaging modalities and include corresponding components. For example, the optical marking 106 may include IR markings, and the imaging system 104 may include an IR camera or image sensor. As another example, the pattern of the optical marking 106 on the deformable surface 109 may include a series of black marks on a white background, white marks on a black background, or any other set of colors that provide an identifiable pattern.
[0021] One problem that must be overcome is that the illumination light may generate visible artifacts such as undesirable reflections and scattered light, which may degrade the image quality of the optical marking 106, which is captured by the imaging system 104 and used to measure the patient's arterial pulsation. To reduce the visibility of such artifacts, in one embodiment of the photomechanical sensor system 100, the optical marking 106 may contain a fluorescent pigment and be illuminated with short-wave EMR such as blue, violet, or UV light. For example, the surface displacement system 108 may include a black deformable surface 109 covered with fluorescent yellow dots as the optical marking 106 configured to glow with short-wave light. The yellow pattern information is displayed in the red and green channels of the color camera, while the blue or violet light is displayed in the blue channel. If UV light is used and the imaging system 104 is insensitive to UV light, the UV light will not be visible to the imaging system 104.
[0022] In another embodiment, the imaging system 104 may include a monochrome camera, and the optical marking 106 may include a fluorescence pattern. For example, if the excitation illumination is blue light and the fluorescence of the optical marking 106 is yellow, the blue light can be blocked by placing a yellow filter over the lens of the monochrome camera, thereby ensuring that only the yellow pattern of the optical marking 106 is visualized. The same principle works with other pairs of excitation light / fluorescence optical marking 106, where the excitation wavelength and emitted wavelength can be separated by the use of color filters.
[0023] Ultraviolet LEDs can be particularly useful for exciting fluorescence. However, one problem that must be overcome is that most ultraviolet LEDs exhibit "spectral leakage," meaning that a small proportion of visible light is emitted along with the invisible UV light. To eliminate this spectral leakage, in one embodiment, the illumination source 112 may include a filter on the LED (e.g., a ZWB1, ZWB2, or ZWB3 glass filter) configured to reduce or remove undesirable visible light, thereby mitigating the effects of spectral leakage from the LED.
[0024] In one embodiment, the deformable surface 109 may include a deformable elastomer gel 120 and a membrane 130 having optical markings 106, as shown in Figure 2. As described above, the patient's wrist 200 includes a radial artery 202 that pulsates during heartbeat. In the shown embodiment, this pulsation causes movement of the soft tissue and skin above the radial artery 202, which in turn deforms the deformable surface 109, which includes the deformable elastomer gel 120 and the membrane 130 with the optical markings 106. In one embodiment, the deformable elastomer gel 120 may be transparent (i.e., translucent or transparent). The optical system 102 may further include a transparent plate 122. The plate may be constructed from polymethyl methacrylate (PMMA) or other such transparent material. In one embodiment, the surface displacement system 108 may be mounted beneath the transparent plate 122, as shown in Figures 2 and 4, so as to be configured to contact the patient's skin when worn by the patient.
[0025] Generally as described above, the surface displacement system 108 can include a dot-like pattern array of various shapes, grids, stripes, and / or lines or other optical markings 106. During use, the optical system 102 is attached to the radial artery 202 at the patient's wrist using a strap 126 attached to a frame 124. The measuring device 102 can be manually pressed against the patient's skin by tightening the strap 126, thereby conforming the surface displacement system 108 to the shape of the wrist, including the skin and tissue above the radial artery 202. Furthermore, the contact force between the surface displacement system 108 and the skin can be adjusted by changing the stiffness of the strap 126.
[0026] Generally as described above, the optical system 102 further includes an imaging system 104. In this embodiment, the imaging system 104 may be positioned on the plate 122 such that it is oriented to visualize the optical markings 106 via the plate 122 and elastomer gel 120 and to form an image of the optical markings 106. Since the elastomer gel 120 and plate 122 are constructed from a transparent material, the imaging system 104 can therefore visualize the optical markings 106 positioned along the film 130. Furthermore, an illumination source 112 can provide illumination to assist the imaging system 104 in visualizing the film 130 and the corresponding optical markings 106.
[0027] Therefore, as the patient's heart beats, the radial artery 202 expands and contracts, thereby moving the optical marking 106 in contact with the skin mainly along the z-axis, as shown in Figure 2. As described above, the imaging system 104 can be oriented at an angle (e.g., an oblique angle) to the optical marking 106. Thus, the z-axis motion of the optical marking 106 appears to the imaging system 104 as y-axis motion, i.e., the optical marking 106 appears to move vertically within the plane of the camera sensor. From the measurement of the y-axis motion of the optical marking 106 in the captured image, the computer system 114 can calculate the corresponding z-axis motion of the optical marking 106. Thus, the spatiotemporal motion of the skin above the radial artery 202 can be determined therefrom. By determining the spatiotemporal motion associated with the radial artery 202, various different cardiopulmonary parameters can be derived therefrom. The arrangement of the imaging system 104 so as to view the surface displacement system 108 obliquely has two main purposes. The first advantage, as mentioned above, is the ability to measure z-axis motion. The second advantage is that the device can have a relatively compact form factor, making it not too bulky and convenient to wear on the wrist.
[0028] Referring now to Figure 3, another embodiment of the photomechanical sensor system 100 utilizing the elastomer gel 120 is shown. However, this embodiment differs from the embodiment shown in Figure 2 in that the actuator 110 is a transparent inflatable component 128 (e.g., a balloon or bag) positioned between the elastomer gel 120 and the plate 122. In this embodiment, the contact force between the surface displacement system 108 and the skin can be adjusted by changing the degree of inflation or air pressure of the inflatable component 128 (i.e., actuator 110) between the plate 122 and the elastomer gel 120. Similar to the embodiment shown in Figure 2, the surface displacement surface 108 conforms to the shape of the wrist, including the skin and tissue above the radial artery 202.
[0029] In this embodiment, the optical system 102 further includes a mirror system 131 configured to allow the imaging system 104 to indirectly visualize the optical marking 106 through it. In another embodiment, the imaging system 104 may be separated from or directly integrated with the patient-worn component of the photomechanical sensor system 100. The mirror system 131 may include one or more mirrors configured to provide the imaging system 104 with a field of view (e.g., at an oblique angle) of the optical marking 106. The optical system 102 may further include one or more lenses 144, as shown in the embodiment of Figure 5.
[0030] In one embodiment, the photomechanical sensor system 100 may include an actuator 110 which is an inflatable component 128 (e.g., a balloon or bag) and a surface displacement system 108 which is a membrane 130 having optical markings 106 as shown in Figure 4. This embodiment differs from the embodiment shown in Figure 2 in that the membrane 130 having optical markings 106 is positioned along the inflatable component 128, as opposed to an elastomer gel 120. The inflatable component 128 can be inflated or deflated with a fluid, i.e., air via a pump 142 operably coupled to the inflatable component 128. The inflatable component 128 can be constructed from, for example, a transparent elastomer material. In one embodiment, the photomechanical sensor system 100 may further include a pressure sensor configured to monitor the pressure within the inflatable component 128 so that a desired pressure or pressure range is maintained. A transparent plate 122 and frame 124, combined with the strap 126, ensure that the inflatable component 128 is held in place against the patient's skin and inflates with a surface displacement system 108 directed toward the patient. In this configuration, the contact force between the surface displacement system 108 and the patient's skin can be varied by changing the stiffness of the strap 126 and / or changing the pressure within the inflatable component 128. In this embodiment, an imaging system 104 may be positioned to visualize the optical marking 106 through the transparent plate 122 and the transparent inflatable component 128 in order to view the optical marking 106 on the deformable surface 108. Similar to the previously described embodiments, the photomechanical sensor system 100 may further include an illumination source 112 that provides illumination to assist in the visualization of the optical marking 106. Similar to the previously described embodiments, as the patient's heart beats, the radial artery 202 pulsates, moving the tissue above it.The imaging system 104 can detect the movement of the optical marking 106, and the photomechanical sensor system 100 can correspondingly determine the spatiotemporal movement associated with the radial artery 202, which can then be used to derive various different cardiopulmonary parameters associated with the patient.
[0031] Referring here to Figure 5, another embodiment of the photomechanical sensor system 100 utilizing an actuator 110 is shown, where the actuator 110 is a rigid box 125 with all sides except the skin side covered by a surface displacement system 108, and thus capable of contacting the patient. In this embodiment, the optical system 102 is located within the rigid box 125. Furthermore, the optical system 102 further includes a mirror system 131 that allows the imaging system 104 to indirectly visualize the optical markings 106 (e.g., at an oblique angle), similar to the embodiment shown in Figure 5. In this embodiment, the rigid box 125 is connected to a pump 142. The surface displacement system 108 can be pressed against the patient's skin by pumping air into and out of the rigid box 125, thereby conforming the surface displacement system 108 to the shape of the wrist, including the skin and tissue above the radial artery 202. Furthermore, the contact force between the surface displacement system 108 and the skin can be adjusted by changing the stiffness of the strap 126.
[0032] Referring here to Figure 6A, another embodiment of the photomechanical sensor system 100 using a piston 160 is shown. In this embodiment, the surface displacement system 108 includes a deformable surface which is an air or fluid-filled bag 128 placed on a film 130 having an optical marking 106. In addition to the transparent plate, this embodiment includes a piston 160 made of a transparent material (e.g., PMMA) configured to move relative to a frame 124 (e.g., perpendicularly). The piston can consist of a rigid transparent material or a soft bag which can be inflated / contracted to act like a piston. Thus, the contact force of the surface displacement system 108 with the patient's skin can be changed by changing the stiffness of the strap 126 and by moving the piston 160. In this embodiment, an imaging system 104 can visualize the optical marking 106 through the transparent piston 160. A light source 114 can provide illumination. When the heart beats again, the superficial arteries pulsate, moving the tissue above them, which can be detected by the imaging system 104 based on the movement of the optical markings 106.
[0033] In one embodiment shown in Figure 6B, the photomechanical sensor system 100 may include an actuator 110, which is an inflatable component 128 (e.g., a balloon or bag) located between the imaging system 114 and the strap 126. The imaging system 114 then comes into contact with a surface displacement system 108, which is a gel elastomer 120 and a film 130 having optical markings 106 as shown in Figure 6B. The inflatable component 128 can be inflated or deflated with a fluid, i.e., air, via a pump 142 operably coupled to the inflatable component 128. In this embodiment, the inflatable component 128 may be constructed from an elastomer material that is durable and does not need to be as optically transparent as the inflatable component in the above configuration. Some examples of durable materials may include polyvinyl chloride, thermoplastic polyurethane, and neoprene. In one embodiment, the photomechanical sensor system 100 may further include a pressure sensor configured to monitor the pressure within the inflatable component 128 so that a desired pressure or pressure range is maintained. In this configuration, the contact force between the surface displacement system 108 and the patient's skin can be altered by changing the stiffness of the strap 126 and / or by changing the pressure within the inflatable component 128. In this embodiment, the imaging system 104 may be positioned to visualize the optical markings 106 on the deformable surface 108 via a transparent plate 122 and a transparent gel elastomer 120. Similar to the previously described embodiments, the photomechanical sensor system 100 may further include an illumination source 112 that provides illumination to assist in the visualization of the optical markings 106. Similar to the previously described embodiments, as the patient's heart beats, the radial artery 202 pulsates, moving the tissue above it. The imaging system 104 can detect the movement of the optical markings 106, and the photomechanical sensor system 100 can correspondingly determine the spatiotemporal movement associated with the radial artery 202, which can then be used to derive various different cardiopulmonary parameters associated with the patient.
[0034] Figures 2–6 show various different embodiments of the photomechanical sensor system 100 for optically measuring z-axis motion using an imaging system 104. In some of these embodiments, the imaging system 104 may include a single camera. In other embodiments, the z-axis position and motion of the optical marking 106 can be measured using other optical methods, including those using one or more cameras. For example, the z-axis position and motion of the optical marking 106 can be measured using stereoscopic vision, structured illumination, time of flight, and other photometric and / or stereo optics techniques. Many of these methods involve the use of multiple cameras or special optical equipment. However, in some embodiments, it may be beneficial for the photomechanical sensor system 100 to use only a single camera and not use or use minimal special equipment in order to reduce the size, cost, and / or complexity of the photomechanical sensor system 100.
[0035] Referring here to Figures 7A–8B, embodiments of the opticmechanical sensor system 100 are shown, which include various components described above, such as the optical system 102, the actuator 110, the surface displacement system 108, and the computer system 114, in an exemplary patient-wearable device. In one embodiment, the device can be embodied as a half-bracelet having a hinge 180 (Figure 7A) that can be used to position the opticmechanical sensor 100 by using an anatomical reference such as the radial styloid process. The hinge 180 may also have an adjustable guide to accommodate various wrist sizes. Positioning is achieved by sliding the device onto the wrist, with the hinge 180 or some other mechanism (e.g., a link, articulated joint, or another adjustable connection) taking the radial styloid process as a reference to consistently position the device. The hinge 180 can then be adjusted based on the wrist size and locked in place. In this embodiment, the contact pressure exerted by the surface displacement system 108 can be adjusted by (i) compressing the two arms of the bracelet using an electric system, (ii) adjusting the pressure of the inflatable component 128 (inflating the inflatable component 128, as generally described above, can increase the tension of the strap 126 and thereby increase the contact pressure), and / or (iii) adjusting the strap 126 (for example, by applying contact force by applying tension to the strap via a manual system such as a ratchet dial, or an automatic system such as a motor that can be used to tighten the strap). In various embodiments, the actuator 110 and / or the surface displacement system 108 may be configured such that the contact pressure exerted on the skin by the surface displacement system 108 is adjustable from 0 to 350 mmHg.
[0036] In some embodiments, the measuring device 102 may be fluid. This may allow the measuring device 102 to be freely worn by an individual throughout the day without the need to remove it when the individual is performing certain activities (e.g., showering). Thus, the measuring device 102 can provide uninterrupted monitoring of the patient's hemodynamic parameters.
[0037] The above description relates to the radial artery 202 of the wrist, but this description is for illustrative purposes only. It will be understood that the hemodynamic parameter monitoring system 100 can also be used in other locations on the patient's body and / or in conjunction with other superficial arteries such as the carotid artery, temporal artery, anterior tibial artery, posterior tibial artery, or brachial artery. Therefore, this disclosure should not be understood as being particularly limited to use in connection with the patient's wrist and / or radial artery 202.
[0038] Optical marking displacement analysis Experimental analysis of various arrangements of the optical markings 106 identified several different candidate patterns and / or imaging system configurations for use with the photomechanical sensor system 100. Furthermore, the experimental analysis determined that the motion of the optical markings 106 could be identified with the specificity and precision required to track the spatiotemporal motion of superficial arteries. Motion analysis of the optical markings 106 can be performed in several different ways. For example, the integration method can be used for motion analysis. This technique allows for the continuous calculation of cumulative displacement (i.e., images captured by the imaging system 104) from one frame to the next. As another example, the reference method can be used for motion analysis. In this technique, displacement is calculated against a single reference frame. While the integration method can provide finer resolution, it may also introduce errors that accumulate over time. Conversely, the reference method can be subject to luminance steady-state conditions that force it to destabilize under sudden perturbations. Regardless of the motion analysis technique used, the results of the motion analysis are used to obtain the temporal variance of the region of interest.
[0039] Experimentally, the coordinate system can be defined with respect to the surface displacement system 108, as shown in Figure 9. Furthermore, the far side 190 and near side 192 of the surface displacement system 108 can be defined by their proximity to the imaging system 104. In practice, the optical markings 106 also become more prominent as the imaging system 104 approaches, due to the angle at which the imaging system 104 is oriented toward the surface displacement system 108. The center of the surface displacement system 108 can be defined as the origin. Using the defined coordinate system, the time mask shown in Figure 10A was developed for the embodiments shown in Figures 2 and 3, and the time mask shown in Figure 10B was developed for the embodiments shown in Figures 4 and 5. The time maps were generated by thresholding the variance using a predetermined value. Different masks can be developed by varying the threshold. The region of interest can be determined from the developed maps described above, and the height map obtained from the initial motion analysis can be filtered to obtain data only from the region of interest. Next, the displacement of the optical marking 106 is averaged over the entire region of interest to obtain a one-dimensional signal over time that shows the average equivalent optical marking displacement over each image frame for a given physical displacement.
[0040] Figure 11A provides a graph of exemplary displacement signals in pixel units (y-axis) as the surface displacement system 108 is displaced over time in the range of 10 to 100 microseconds (x-axis) using a simple micrometer for the embodiments shown in Figures 2 and 3. Figure 11B provides a graph of exemplary displacement signals in pixel units (y-axis) as the surface displacement system 108 is displaced over time in the range of 10 to 100 microseconds (x-axis) using a simple micrometer for the embodiments shown in Figures 4 and 5. These graphs provide an understanding of how surface displacement is measured in the photomechanical system 100.
[0041] As seen in Figures 11A and 11B, the displacement of the optical marking 106 can be tracked over time. Tracking the temporal displacement of the optical marking 106 provides the ability to map the temporal displacement of each pixel in a given image over an area of the image (e.g., 40 mm × 30 mm). Figures 12A and 12B show surface displacement plots obtained by measuring the maximum displacement of the optical marking 106 at a given pixel for embodiments shown in Figures 2 and 3, and Figures 4 and 5, respectively. This can generate surface displacement plots of all pixels at each point in time (e.g., 30 ms) providing corresponding high temporal resolution displacement information. This spatiotemporal displacement information can be used to identify and monitor pulsations in arteries, which can then be used to monitor the hemodynamic state of a patient. Due to the high temporal resolution, the optical system 102 can identify sub-pixel movements resulting from the displacement of the optical marking 106, which may be important for identifying physiologically important parameters such as overlapping bulges in blood pressure signals.
[0042] While various exemplary embodiments incorporating the principles of this teaching are disclosed, this teaching is not limited to the disclosed embodiments. Rather, this application is intended to encompass any variations, uses, or adaptations of this teaching and to utilize its general principles. Furthermore, this application is intended to encompass deviations from this disclosure such that these teachings fall within the scope of known or customary practices in the relevant art.
[0043] The detailed description above refers to the accompanying drawings which form part of this specification. In the drawings, unless the context otherwise indicates, similar symbols typically identify similar components. The exemplary embodiments described herein are not intended to limit. Other embodiments may be used and other modifications may be made without departing from the spirit or scope of the subject matter presented herein. The various features of this disclosure can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, as generally described herein and shown in the figures, and it will be readily understood that all of these are expressly intended herein.
[0044] This disclosure is not limited to the specific embodiments described herein, which are intended to illustrate a variety of features. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from its spirit and scope. In addition to those enumerated herein, functionally equivalent methods and apparatus within the scope of this disclosure will be apparent to those skilled in the art from the foregoing description. This disclosure is not limited to specific methods, reagents, compounds, compositions, or biological systems, which are, of course, subject to change. It should also be understood that the terminology used herein is intended to describe only specific embodiments and is not intended to limit them.
[0045] With regard to the use of substantially any plural and / or singular terms herein, those skilled in the art can translate from plural to singular and / or singular to plural as appropriate to the context and / or use. For clarity, various singular / plural permutations may be explicitly listed herein.
[0046] In general, those skilled in the art will understand that the terms used herein are generally intended to be “open” terms (for example, the term “includes” should be interpreted as “includes, but not limited to” the term “have”). While various compositions, methods, and devices are described using the term “includes” (to be interpreted as “includes, but not limited to”), compositions, methods, and devices can also “essentially consist of” or “consist of” various components and steps, and such terminology should be interpreted as defining an essentially closed group of members.
[0047] Furthermore, even if a specific number is explicitly stated, a person skilled in the art will recognize that such a statement should be interpreted as meaning at least the stated number (for example, the literal statement of “two statements” without other modifiers means at least two statements, or two or more statements). Furthermore, when a convention similar to “at least one of A, B, and C, etc.” is used, such a construction is generally intended in a way that a person skilled in the art will understand the convention (for example, “a system having at least one of A, B, and C” includes, but is not limited to, systems having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B and C together, etc.). Where a clause similar to “at least one of A, B, or C, etc.” is used, such a configuration is generally intended to be understood by a person skilled in the art (for example, “a system having at least one of A, B, or C, etc.” includes, but is not limited to, a system having A alone, B alone, C alone, a system having A and B together, a system having A and C together, a system having B and C together, and / or a system having A, B and C together, etc.). It will be further understood by a person skilled in the art that virtually all disjunctive words and / or phrases presenting two or more alternative terms in any description, illustrative embodiment, or drawing should be understood to contemplate the possibility of including one of the terms, either of the terms, or both of the terms. For example, the phrase “A or B” would be understood to include the possibilities of “A” or “B” or “A and B”.
[0048] Furthermore, where the features of this disclosure are described in relation to the Markush Group, a person skilled in the art will understand that they also describe any individual member or a subgroup of members of the Markush Group.
[0049] As will be understood by those skilled in the art, for all purposes, including providing written descriptions, all scopes disclosed herein also encompass all possible sub-scopes and combinations thereof. It will be readily apparent that each listed scope is sufficiently described so that the same scope can be divided into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each scope described herein can be readily broken down into lower thirds, middle thirds, upper thirds, etc. Also, as will be understood by those skilled in the art, all language such as “maximum” and “at least” includes the number listed and refers to a scope that can be divided into sub-scopes as described above. Finally, as will be understood by those skilled in the art, a scope includes its individual members. Thus, for example, a group having 1 to 3 cells refers to a group having 1, 2, or 3 cells. Similarly, a group having 1 to 5 cells refers to a group having 1, 2, 3, 4, or 5 cells, and so on.
[0050] As used herein, the term “approximately” refers to variations in numerical quantities that may arise, for example, from real-world measurement or handling procedures, inadvertent errors in these procedures, the manufacture of a composition or reagent, the source, or differences in purity. Typically, as used herein, the term “approximately” means greater than or less than one-tenth of the stated value, for example, a value or range of values indicated by ±10%. The term “approximately” also refers to a variation that would be recognized as equivalent by a person skilled in the art, unless such variation encompasses known values implemented by the prior art. Each value or range of a value preceding the term “approximately” is also intended to encompass embodiments of the stated absolute value or range of values. Whether modified by the term “approximately” or not, the quantitative values enumerated in this disclosure will be recognized as equivalent by a person skilled in the art, including possible variations in the numerical quantities of such values.
[0051] The features and functions disclosed above, or various alternatives thereof, can be combined with many other different systems or applications. Various alternatives, modifications, variations, or improvements that are not currently foreseeable or anticipated may subsequently be made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.
[0052] The functions and processing steps described herein may be executed automatically, or entirely or partially, in response to user commands. Activities (including steps) that are executed automatically are performed in response to one or more executable instructions or device operations without the user directly initiating the activity.
Claims
1. A photomechanical sensor system for use with patients, A patient-wearable surface displacement system, A deformable surface configured to be positioned adjacent to the superficial artery of the patient, A patient-wearable surface displacement system comprising a plurality of markings disposed on or within the deformable surface, wherein the plurality of markings are configured to reflect or emit electromagnetic radiation (EMR), and the photomechanical sensor system is An actuator configured to apply pressure to hold the patient-wearing surface displacement system against the patient such that the movement of the superficial arteries, along with the plurality of markings, causes corresponding movement of the deformable surface, An imaging system configured at an oblique angle to the multiple markings so as the multiple markings move in conjunction with the movement of the superficial artery, the imaging system visualizes the multiple markings through at least one translucent or transparent layer positioned between the imaging system and the multiple markings, A lighting source configured to illuminate the plurality of markings to assist in the visualization of the plurality of markings through the at least one translucent or transparent layer as the markings move along with the movement of the deformable surface, A computer system coupled to the imaging system, wherein the computer system includes a processor and memory, and the memory, when executed by the processor, the computer system The imaging system receives a plurality of images, including the plurality of markings, that are irradiated by the illumination source. Based on the multiple images received, the movement of the irradiated marking is determined, and A computer system that stores commands for determining cardiopulmonary parameters associated with the patient based on the determined movement of the irradiated marking, A housing comprising the patient-worn surface displacement system and the imaging system, wherein the housing is coupled to a hinged half-bracelet configured to consistently position the photomechanical sensor system relative to the patient's wrist by using the radial styloid process as an anatomical reference, An optical mechanical sensor system further equipped with [features].
2. The photomechanical sensor system according to claim 1, wherein the deformable surface is selected from the group consisting of elastomer gels, fluid-filled balloons, membranes, and combinations thereof.
3. The optical mechanical sensor system according to claim 1, wherein the actuator is selected from a group consisting of a piston configured to move to adjust the pressure on the deformable surface, an inflatable bag, an adjustable strap, a chamber coupled to an air pump, and combinations thereof.
4. The optical mechanical sensor system according to claim 1, wherein the superficial artery includes the radial artery.
5. The optical mechanical sensor system according to claim 1, wherein the cardiopulmonary parameters are selected from a group consisting of heart rate, blood pressure, respiratory rate, and combinations thereof.
6. The optical system further comprises a mirror system configured to visualize the plurality of markings at an oblique angle to the imaging system, according to claim 1.
7. The optical mechanical sensor system according to claim 1, wherein the imaging system is separated from the patient-worn surface displacement system.
8. The photomechanical sensor system according to claim 1, wherein the plurality of markings include optically visible markings.
9. The photomechanical sensor system according to claim 1, wherein the plurality of markings include fluorescent markings.
10. The photomechanical sensor system according to claim 1, wherein the at least one translucent or transparent layer is a transparent layer that is part of a balloon or elastomer gel.
11. A method for monitoring a patient's cardiopulmonary parameters using an optical mechanical sensor system, The photomechanical sensor system comprises a deformable surface, a plurality of markings disposed on or within the deformable surface, and an actuator configured to apply pressure to hold the surface displacement system against the patient, and the method is A step of attaching a surface displacement system adjacent to the superficial artery of the patient, the step of attaching the surface displacement system includes positioning the surface displacement system on the patient's wrist with respect to the radial styloid process using a hinged half-bracelet, the surface displacement system comprising the deformable surface, the plurality of markings, and at least one translucent or transparent layer, the plurality of markings being configured to reflect or emit electromagnetic radiation (EMR), and the step of attaching, The steps include causing the actuator to apply pressure to hold the surface displacement system against the patient, so that the movement of the superficial artery causes the corresponding movement of the deformable surface along with the plurality of markings, The steps include illuminating the plurality of markings through a light source to assist in the visualization of the plurality of markings through the at least one translucent or transparent layer as the plurality of markings move with the movement of the deformable surface, The steps include capturing a plurality of images, including the plurality of markings illuminated by the illumination source through the at least one translucent or transparent layer positioned between the imaging system and the plurality of markings, as the plurality of markings move along with the movement of the superficial artery, via an imaging system positioned at an oblique angle to the plurality of markings; The steps include determining the movement of the illuminated marking based on the plurality of images received via a computer system, and The steps of determining cardiopulmonary parameters associated with the patient based on the determined movement of the irradiated marking via the computer system, A method for providing it.
12. The method according to claim 11, wherein the deformable surface is selected from the group consisting of elastomer gels, fluid-filled balloons, membranes, and combinations thereof.
13. The method according to claim 11, wherein the actuator is selected from a group comprising a piston configured to move to adjust the pressure on the deformable surface, an inflatable bag, an adjustable strap, a chamber coupled to an air pump, and combinations thereof.
14. The method according to claim 11, wherein the superficial artery includes the radial artery.
15. The method according to claim 11, wherein the cardiopulmonary parameters are selected from a group consisting of heart rate, blood pressure, respiratory rate, or a combination thereof.
16. The photomechanical sensor system according to claim 1, wherein the illumination source generates shortwave light to illuminate the plurality of markings and reduces artifacts caused by reflected or scattered light.
17. The photomechanical sensor system according to claim 16, wherein the short-wave light is blue light, violet light, or ultraviolet light, and the patient-worn surface displacement system further comprises an imaging filter adjacent to the imaging system, the imaging filter being configured to allow the short-wave light to pass through the imaging filter and reach the imaging system, while blocking at least one EMR spectrum other than the short-wave light from being received by the imaging system.
18. The photomechanical sensor system according to claim 16, wherein the plurality of markings include fluorescent pigments.
19. The optical mechanical sensor system according to claim 1, wherein the actuator is a piston controlled by the computer system and operably coupled to the deformable surface to apply pressure to hold the patient-wearing surface displacement system with respect to at least the superficial arteries.