SG183589A1 - Conductive fabric based system and method for sensing or monitoring physiological parameters - Google Patents

Abstract

CONDUCTIVE FABRIC BASED SYSTEM AND METHOD FOR SENSING OR MONITORING PHYSIOLOGIC PARAMETERSAbstractA conductive fabric based physiologic parameter sensing system includes at least two conductive fabric electrodes capacitively couplable to a portion of a subject's body, and which are coupled to a sensing interface unit. The sensing interface unit can selectively couple a conductive fabric electrode to an excitation source (e.g., a Wien bridge oscillator) configured to provide a time-varying subject-extrinsic electric field or signal in accordance with an active sensing configuration; or electrically isolate the conductive fabric electrodes from the excitation source in accordance with a passive sensing configuration. In an active sensing configuration, a given electrode (or electrodes) applies the subject-extrinsic signal to the portion of the subject's body, and another electrode (or electrodes) detects a response electric field corresponding to a manner in which the portion of the subject's body affects the applied field. In a passive sensing configuration, electrode pairs detect electric signals that are intrinsically generated by the portion of the subject's body. The system can analyze sampled data values, and generate corresponding physiologic parameter values, a physiologic parameter waveform, and/or subject status information, a notification, or an alert. The system can additionally present (e.g., display) or communicate (e.g., over a network) subject-related information, signals, or data corresponding to a fluid state, a breathing related parameter, a motion related parameter, and/or a cardiac parameter of the subject.FIG. 1

Description

CONDUCTIVE FABRIC BASED SYSTEM AND METHOD FOR

SENSING OR MONITORING PHYSIOLOGIC PARAMETERS

Technical Field

The present disclosure relates generally to sensors, sensor assemblies, or sensing elements made substantially from conductive textile material, and which are configured to sense physiologic parameters of a patient in the absence of direct electrical contact with patient skin. Such sensor assemblies can be integrated into coverings for subject or patient support structures such as beds. Sensing assemblies can be configured for active sensing, which involves detecting a manner in which the subject’s body affects an extrinsic or externally generated electric field or signal; and/or passive sensing, which involves sensing electric signals that are intrinsically generated by the subject’s body itself.

Background

There are a number of conventional systems, apparatuses, and methods for sensing or capturing physiologic parameters of a body of a patient. Medical electrodes are commonly used for sensing or capturing signals (e.g., electrical signals) that are generated by the patient’s body. Most commonly, these electrodes or sensors include conductive patches or pads that are connected to monitoring equipment via electrical leads or wires. The electrodes commonly include adhesive backings for adhering the conductive pads onto the patient’s skin in a manner that facilitates electrical signal transfer. A conductive gel or paste is often applied at the interface between the conductive pad and the patient’s skin to enhance the capture of bodily signals by the conductive pads (e.g., by increasing conductive surface contact area and/or reducing interface impedance).

Unfortunately, such electrodes have been known to cause patient discomfort such as skin irritation or chafing, and even skin lesions, particularly if they remain on the patient’s skin for a prolonged period of time. Additionally, electrodes can be difficult to detach from the body, again leading to patient discomfort. Furthermore, patient motion can give rise to sensing inaccuracy or unreliability in the event that such motion partially or fully detaches one or more electrodes from the patients’ body. Moreover, the presence of lead wires can undesirably constrain patient motion, particularly in situations involving a large number of electrodes and lead wires.

In an attempt to reduce patient discomfort, certain types of medical electrodes have been incorporated into stretchable structures. For instance, U.S. Patent Nos. 4,722,354 and 5,450,845 describe electrodes that integrate wire-based electrical leads into stretchable, conductive fabric patch structures in order to provide electrodes that better conform to patient anatomy or accommodate patient movement. However, such electrodes are directly adhered to the patient’s body in order to establish a conduction current path between the electrode and the patient’s skin. As with other types of patch electrodes, adhesion to the patient’s body can lead to patient discomfort or skin lesions, and/or measurement inaccuracies, especially in long term monitoring situations.

More recently, systems have been developed for measuring particular types of physiologic parameters in the absence of electrodes that establish direct electrical contact (i.e., a conduction current path) with the patient’s skin. For instance, U.S. Patent No. 4,807,640 describes a chest fitted band-like textile structure that carries a network of electrical wires, and which performs respiratory sensing through changes in self- inductance in the network of wires that is induced by stretching of the textile structure.

However, accurate measurement using this structure requires that the network of electrical wires fit snugly around the patient’s torso, which can again lead to patient discomfort.

Other types of non-contact physiologic parameter measurement systems have been developed that utilize sensors configured to detect changes in patient biopotentials by way of sensing impedance changes corresponding to particular types of physiologic parameters. Such systems include those described in U.S. Patent Application Publication

No. 20080183063, which utilizes conductive fabric sensors that are integrated into a covering (e.g., a sheet) for a patient; and U.S. Patent No. 7,245,956, which utilizes sensors (e.g., capacitive sensors) that are integrated into an object such as a mattress or bed.

Integrating impedance based sensors into bedding or beds can enhance patient comfort, as well as the convenience and ease of obtaining particular physiologic parameters from patients, especially when the patients are substantially bedridden. In addition, integrating impedance based sensors into structures such as beds can facilitate long-term or continual sensing or monitoring of particular physiologic parameter(s) of the body of patients.

However, prior systems and techniques directed to non-contact physiologic parameter measurement are undesirably limited with respect to the types of physiologic parameters and/or patient conditions they can be configured to detect or monitor.

The increasing demand for enhanced quality and accuracy of medical surveillance, diagnosis, and/or analysis, and patient care procedures, is likely to result in a need for new or enhanced systems and techniques for sensing, monitoring, or analyzing physiologic parameters.

Summary

In accordance with an aspect of the disclosure, a process for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body includes coupling a plurality of electrodes to an excitation source; generating a subject-extrinsic time varying electrical signal using the excitation source; generating a subject-extrinsic time varying electric field using the plurality of electrodes; exposing the portion of the subject’s body to the subject-extrinsic time varying electric field; and detecting a manner in which the portion of the subject’s body affects the subject-extrinsic time varying electric field, wherein at least one electrode within the plurality of electrodes includes a conductive fabric electrode. In various embodiments, the excitation source can include a

Wien bridge oscillator.

Detecting a manner in which the portion of the subject’s body affects the subject- extrinsic time varying electric field can include detecting a circuit parameter corresponding to a first electrode and a second electrode within the plurality of electrodes. For instance, the circuit parameter can include an electrical current parameter and/or a voltage parameter. The manner in which the portion of the subject’s body affects the subject-extrinsic time varying electric field can be correlated with a time varying dielectric characteristic corresponding to the portion of the subject’s body.

The conductive fabric electrode can be capacitively coupled to the portion of the subject’s body. Additionally, the portion of the subject’s body and the conductive fabric electrode can be substantially freely movable relative to each other. In some embodiments, the plurality of electrodes includes a first conductive fabric electrode and a second conductive fabric electrode, each of which can be capacitively coupled to the portion of the subject’s body. The portion of the subject’s body can be substantially movable with respect to each of the first conductive fabric electrode and the second conductive fabric electrode.

In accordance with an aspect of the disclosure, a process for acquiring and processing signals correlated with a physiologic state of a first portion of a subject’s body can include providing a first electrode and a second electrode, at least one of the first and second electrodes including a conductive fabric electrode; identifying a first physiologic parameter (e.g., corresponding to one of a fluid state, a breathing related parameter, a motion related parameter, and a cardiac parameter of the subject) to be detected; determining whether the first physiologic parameter is detectable by way of an active sensing configuration that involves exposing the first portion of the subject’s body to a subject-extrinsic time varying electric field or a passive sensing configuration that avoids exposing the first portion of the subject’s body to the subject-extrinsic time varying electric field; and selectively (a) coupling each of the first electrode and the second electrode to an excitation source; or (b) isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the first physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration. In multiple embodiments, the excitation source can include a Wien bridge oscillator. Coupling each of the first electrode and the second electrode to the excitation source can include automatically coupling at least one of the first electrode and the second electrode to the excitation source.

The aforementioned process can further include capacitively coupling the first electrode and the second electrode to the first portion of the subject’s body; and generating a differential signal corresponding to a signal difference between the first electrode and the second electrode. In a passive sensing configuration, the differential signal can correspond to a subject-intrinsic electrical signal detected using the first electrode and the second electrode. The differential signal can be correlated with a time varying dielectric characteristic corresponding to the first portion of the subject’s body. More particularly with respect to an active sensing configuration, the differential signal can be correlated with a manner in which the time varying dielectric characteristic affects the subject- extrinsic time varying electric field.

A process in accordance with the present disclosure can include storing sampled data corresponding to a differential signal, and in some embodiments processing sampled data corresponding to the differential signal to generate a representation of the first physiologic parameter.

A process in accordance with the present disclosure can include generating a subject- extrinsic time varying electrical signal using the excitation source; generating the subject- extrinsic time varying electric field using the first and second electrodes; and detecting a manner in which the first portion of the subject’s body affects the subject-extrinsic time varying electric field. Detecting a manner in which the first portion of the subject’s body affects the subject-extrinsic time varying electric field can include detecting a manner in which a time varying dielectric characteristic corresponding to the first portion of the subject’s body affects the subject-extrinsic time varying electric field. In some embodiments, detecting a manner in which the first portion of the subject’s body affects the subject-extrinsic time varying electric field can include detecting or sensing an electrical circuit parameter, for instance, an electrical current and/or a voltage parameter, corresponding to the first electrode and the second electrode.

A process in accordance with an embodiment of the disclosure can include communicating at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network. Additionally or alternatively, a process in accordance with an embodiment of the disclosure can include displaying at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert on a display device.

A process in accordance with an embodiment of the disclosure can further include identifying a second physiologic parameter (e.g., corresponding to one of a fluid state, a breathing related parameter, a motion related parameter, and a cardiac parameter of the subject) to be sensed, the second physiologic parameter distinguishable from the first physiologic parameter; determining whether the second physiologic parameter is detectable by way of an active sensing configuration that involves exposing a second portion of the subject’s body to the time varying subject-extrinsic electric field or a passive sensing configuration that avoids exposing the second portion of the subject’s body to the time varying subject-extrinsic electric field; and selectively (a) coupling each of the first electrode and the second electrode to the excitation source; or (b) isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the second physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration.

Depending upon embodiment details and/or the nature of the first and second physiologic parameters, wherein the first portion of the subject’s body and the second portion of the subject’s body can be identical or at least substantially identical; or the second portion of the subject’s body can be at least substantially different or entirely different than the first portion of the subject’s body.

The aforementioned process can further include detecting a first set of signals corresponding to the first physiologic parameter by way of an active sensing configuration; and detecting a second set of signals corresponding to the second physiologic parameter by way of a passive sensing configuration.

In accordance with an aspect of the disclosure, a system for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body includes a first electrode; a second electrode; an excitation source configured to generate a subject- extrinsic time varying electric signal; a sensing interface unit configured to selectively establish (a) an active sensing configuration in which each of the first electrode and the second electrode is coupled to the excitation source; and (b) a passive sensing in which each of the first electrode and the second electrode is electrically isolated from the excitation source; and a signal acquisition unit coupled to the first electrode and the second electrode and configured to generate sampled data corresponding to a set of signals carried by the set of electrodes, wherein at least one of the first electrode and the second electrode includes a conductive fabric electrode. In some embodiments, each of the first electrode and the second electrode includes a conductive fabric electrode. The first and second electrodes are capacitively couplable to the portion of the subject’s body.

Additionally, in multiple embodiments, the excitation source includes a Wien bridge oscillator.

In several embodiments, the system includes a subject support structure that carries the first and/or second electrodes. The subject support structure can include one of a bed, a table, a chair, and an animal enclosure. In some embodiments, the system includes one of a covering and a bedding material configured to carry a conductive fabric electrode.

A system such as that described above can include a control unit coupled to the sensing unit, the control unit including a memory configured to store sampled data; and a processing unit configured to process sampled data. The control unit can further include a sensing control module configured to selectively direct the sensing interface unit to establish an active sensing configuration or a passive sensing configuration. The sensing control module can be responsive to signals or commands received from the control unit, such that the sensing control module can establish an active sensing configuration or a passive sensing configuration based upon user input corresponding to user identification of a physiologic parameter.

The control unit can further include one or each of a parameter analysis module configured to process sampled data in accordance with a physiologic parameter under consideration; a parameter communication module configured to communicate at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network; and a parameter presentation module configured to direct the display of at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert.

A computer readable medium in accordance with an aspect of the disclosure stores program instructions configured to direct operations performed by a system for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body, the system comprising a first electrode and a second electrode capacitively couplable to the subject, a sensing control and interface unit, an excitation source configured to generate a subject-extrinsic time varying electrical signal, and a control unit comprising a processor and a memory, at least one of the first electrode and the second electrode including a conductive fabric electrode, the program instructions when executed causing the system to identify a first physiologic parameter (e.g., a fluid state, a breathing related parameter, a motion related parameter, and/or a cardiac parameter) of the subject to be detected; determine whether the first physiologic parameter is detectable by way of an active sensing configuration that involves an application of a subject-extrinsic time varying electric field to the portion of the patient’s body or a passive sensing configuration that avoids the application of a subject-extrinsic time varying electric field to the portion of the patient’s body; and selectively (a) couple the first electrode and the second electrode to the excitation source; or (b) electrically isolate each of the first electrode and the second electrode from the excitation source based upon determining whether the first physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration.

The aforementioned computer readable medium can further store program instructions that when executed cause the system to communicate at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network.

The computer readable medium can additionally or alternatively store program instructions that when executed cause the system to display at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert.

The aforementioned computer readable medium can further store program instructions that when executed cause the system to identify a second physiologic parameter (e.g., a fluid state, a breathing related parameter, a motion related parameter, and/or a cardiac parameter of the subject) to be sensed, the second physiologic parameter distinguishable from the first physiologic parameter; determine whether the second physiologic parameter is detectable by way of an active sensing configuration that involves an application of a subject-extrinsic time varying electric field to the portion of the patient’s body or a passive sensing configuration that avoids the application of a subject-extrinsic time varying electric field to the portion of the patient’s body; and selectively (a) coupling the first electrode and the second electrode to the excitation source; or (b) electrically isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the second physiologic parameter corresponds to an active sensing configuration or a passive sensing configuration.

Brief Description of the Drawings

FIG. 1 is a schematic illustration of a conductive fabric based physiologic parameter sensing system according to an embodiment of the disclosure.

FIG. 2A is a representative illustration of an active sensing configuration according to an embodiment of the disclosure.

FIG. 2B is a representative illustration of a passive sensing configuration according to an embodiment of the disclosure.

FIG. 3A is a schematic block diagram illustrating a sensing interface unit according to an embodiment of the disclosure, which can be configured or programmed to operate in an active sensing mode or a passive sensing mode.

FIG. 3B is a schematic circuit diagram of an excitation source according to an embodiment of the disclosure.

FIG. 4 is a block diagram of a representative control unit according to an embodiment of the disclosure.

FIG. 5A is a flow diagram of a process for monitoring or sensing physiologic parameters according to an embodiment of the disclosure.

FIG. 5B is a flow diagram of a process for determining or estimating a patient state and generating patient status information, notifications, and/or alerts according to an embodiment of the disclosure.

FIG. 6A is a flow diagram of a process for acquiring, processing, communicating, and/or presenting information corresponding to patient breathing or respiration according to an embodiment of the disclosure.

FIG. 6B is a graph illustrating a representative breathing pattern that can be detected by embodiments of the present disclosure.

FIG. 7A is a flow diagram of a process for acquiring, processing, communicating, and/or presenting information corresponding to a target body region fluid state according to an embodiment of the disclosure.

FIG. 7B is a graph illustrating a representative fluid state measurement over time corresponding to a target body region in accordance with an embodiment of the present disclosure.

FIG. 8A is a flow diagram of a process for acquiring, processing, communicating, and/or presenting information corresponding to patient cardiac parameters according to an embodiment of the disclosure.

FIG. 8B is a graph illustrating a representative cardiac pattern that can be detected by embodiments of the disclosure.

Detailed Description

Embodiments of the present disclosure relate to systems, apparatuses, assemblies, structures, and/or processes for sensing, capturing, or monitoring physiologic parameters or physiologic parameter correlates of a subject or patient. For purposes of the present disclosure, the subject or patient can be a human or an animal (e.g., a nonhuman mammal). Within portions of the description provided herein, the terms subject and patient may be used interchangeably. Representative examples of subject physiologic parameters include, but are not limited to, heartbeat characteristics such as heart rate and electrocardiogram (ECG); aspects of subject motion; aspects of breathing rate and/or breath amplitude; and a fluid state of one or more bodily organs. A physiologic parameter correlate can be a detected, measured, and/or processed signal that is related to or indicative of a physiologic parameter.

The ability to monitor particular physiologic parameters of a patient can facilitate or enable the monitoring of the subject’s physiologic state and/or one or more corresponding or underlying physiologic conditions of the subject. Several embodiments of the disclosure thus additionally relate to systems, apparatuses, assemblies, methods, and/or processes for determining, evaluating, analyzing, and/or verifying a subject’s physiologic condition. Representative examples of a physiologic condition of the subject include, but are not limited to, cardiovascular conditions such as angina, arrhythmia, atrial fibrillation, heart attack, and heart failure; respiratory conditions such as asthma, sleep apnea, chronic bronchitis, adult respiratory distress syndrome, allergies that give rise to breathing related symptoms, emphysema, and respiratory infections; seizure state associated with epilepsy; and renal conditions such as kidney failure.

Selected embodiments of the present disclosure relate to systems, apparatuses, assemblies, devices, methods, and/or processes for enhancing current standards of subject or patient care. For example, systems, apparatuses, assemblies, methods, and/or processes of selected embodiments enable a less cumbersome, faster, or more convenient capture of physiologic parameters; a more rapid or accurate understanding of physiologic state or diagnosis of a physiologic condition (e.g., disease state or disease progression); and/or more comprehensive subject monitoring or surveillance techniques.

In accordance with embodiments of the disclosure, a conductive fabric based system for sensing, capturing, or monitoring a set of subject or patient physiologic parameters and/or physiologic parameter correlates includes one or more sensing or electrical signal transfer elements that are constructed entirely or substantially from a conductive textile or fabric material. In various embodiments, conductive fabric sensing elements can be carried by a material layer or covering for a subject or a subject support structure. Representative examples of subject or subject support structures include a bed and/or a mattress, a surgical table, and a seating device such as a chair, a recliner, or a wheelchair. In a number of embodiments, particular conductive fabric sensing elements can be integrated or woven into and/or onto coverings such as a mattress pad, a sheet, blanket, pillow case, a cushion, or the like. Additionally or alternatively, conductive fabric sensing elements can be carried by a portion (e.g., an outer or inner surface) of a subject support structure or device itself.

In certain embodiments, a conductive fabric based system for sensing, capturing, or monitoring a set of subject physiologic parameters and/or physiologic parameter correlates includes a set of conductive fabric electrical signal transfer elements (e.g., conductive fabric electrodes and/or corresponding conductive fabric signal transfer pathways) carried by or disposed relative to a subject support structure configured to support a portion of an animal’s body, or carried by material layers or coverings associated with an animal body support structure. Such a support structure can correspond, for instance, to an animal enclosure or animal living quarters, and can be associated with a veterinary, animal park, animal laboratory, or other type of animal related environment.

In addition to conductive fabric sensing elements, a conductive fabric based system for sensing physiologic parameters can include a sensing interface unit coupled or couplable to the conductive fabric sensing elements; a control unit coupled to the sensing interface unit; and an output, notification, or display device coupled to the control unit. The sensing interface unit can select or establish manners in which the conductive fabric sensing elements are configured to carry and/or detect electrical signals corresponding to subject physiologic parameters. Additionally, in various embodiments the sensing interface unit can acquire or sample signals carried by the conductive fabric sensing elements; convert sampled signals to digital data values; and transfer sampled data values to the control unit.

As further detailed below, in multiple embodiments the sensing interface unit can selectively configure the conductive fabric sensing elements to operate in accordance with an active sensing mode or a passive sensing mode. An active sensing mode can involve the generation of an extrinsic or subject-external time varying or oscillatory field or signal; the exposure of a target subject body region to the subject-extrinsic signal; and the detection a manner in which the target subject body region affects, modifies, or perturbs the time varying signal (e.g., as a result of a subject-intrinsic process) at one or more times. A passive sensing mode can involve the detection of electrophysiologic or bioelectric signals that are intrinsically generated within or proximate to the target subject body region itself. Any given conductive fabric electrode can be capacitively coupled to the subject’s body in a manner that facilitates or enables active mode or passive mode sensing operations in accordance with an embodiment of the present disclosure.

The control unit can manage or direct the operation of the sensing interface unit, and can analyze and/or process sampled data values received therefrom to determine or generate subject-related information such as physiologic signal values, physiologic signal waveforms, subject status information, and/or alerts at one or more times. The control unit can transfer particular subject-related information to the notification device, which can output, present, or display such information (e.g., on a regular and/or as-needed basis). Additionally or alternatively, the control unit can direct the communication of particular subject-related information to other (e.g., remote) systems or devices, for instance, by way of a network such as a local area network (LAN), a wide area network (WAN), or the Internet.

Depending upon embodiment details, portions of a conductive fabric based system for sensing or monitoring subject physiologic parameters can be implemented by way of hardware and/or software, for instance, computer or computing device hardware and/or software.

Representative aspects of systems, apparatuses, devices, circuits and processes that involve conductive fabric sensing elements configured for detecting or monitoring physiologic parameters in accordance with embodiments of the present disclosure are described in detail hereafter with reference to FIG. 1 to FIG. 8B, in which like or analogous elements or process portions are shown numbered with like or analogous reference numerals. Relative to descriptive material corresponding to one or more of

FIGs. 1 — 8B, the recitation of a given reference numeral can indicate simultaneous consideration of a FIG. in which such reference numeral was previously shown. The embodiments provided by the present disclosure are not precluded from applications in which particular fundamental structural and/or operational principles present among the various embodiments described herein are desired.

In the context of the present disclosure, the term “set” is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a singlet or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in An Introduction to Mathematical Reasoning: Numbers,

Sets, and Functions, “Chapter 11: Properties of Finite Sets” (e.g., as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)). In general, an element of a set can include or be a structure, a device, a signal, a function or functional process, or a value depending upon the type of set under consideration.

Aspects of Representative Sensing System Embodiments

FIG. 1 is a schematic illustration of portions of a representative conductive fabric based physiologic parameter sensing or monitoring system 10 according to an embodiment of the disclosure. In various embodiments, the system 10 includes a sensing surface, material, layer, or covering 30 that carries one or more conductive fabric sensing elements or electrodes 50a-c, and which is configured to overlay or reside upon, proximate to, or within a portion of a subject support device 20 such as a bed, a table, a chair, or an animal enclosure. The system 10 further includes a sensing interface unit 100 coupled to the conductive fabric electrodes 50a-c; and a control unit 200 coupled to the sensing interface unit 100.

In general, the sensing covering 30 includes one or more nonconductive portions or regions 32 that separate conductive fabric electrodes 50a-c from each other, and which facilitate or enable electrical isolation between individual conductive fabric electrodes 50a-c with respect to conduction current transfer. Any given nonconductive portion 32 can be formed from a conventional nonconductive fabric or textile. The conductive fabric electrodes 50a-c can be manufactured or fabricated using a conductive textile. In various embodiments, particular conductive fabric electrodes S0a-c can be interwoven or integrated into portions of the sensing covering 30. Additionally or alternatively, one or more conductive fabric electrodes 50a-c can be stitched or adhered onto or adjacent to portions of the sensing covering 30. In a representative implementation, each of the conductive fabric electrodes 50a-c can be formed using conductive fabric tapes as supplied by manufacturers such as Laird Technologies (Laird Technologies, St. Louis,

MO, USA).

With respect to tactile characteristics such as texture and/or flexibility, the conductive fabric electrodes 50a-c can be essentially or generally indistinguishable from non- conductive portions 32 of the sensing covering 30. With respect to electrical characteristics, the conductive fabric electrodes 50a-c can exhibit far less than 1kOhms in impedance and may be implemented using conductive fabric exhibiting surface resitivities of less than 0.1 Ohm/square.

In a number of embodiments, a set of conductive fabric electrodes 50 includes at least a first electrode 50a and a second electrode 50b, and optionally a third electrode 50c, each of which is formed or substantially formed from conductive textile or fabric. As further detailed below, depending upon embodiment details and/or a sensing configuration under consideration, the sensing interface unit 100 can electrically configure particular conductive fabric electrodes 50a-c as a positive electrode, a negative electrode, a reference electrode, and/or an excitation electrode. Thus, the sensing interface unit 100 can selectively capacitively couple the first conductive fabric electrode 50a, the second conductive fabric electrode 50b, and/or the third conductive fabric electrode 50c to the subject’s body, depending upon a physiologic parameter or sensing configuration under consideration. Such electrical configuration can occur on a selective basis, for instance, at one or more times in response to commands or instructions received from the control unit 200. Additionally, such electrical configuration can occur on an automatic or semi- automatic basis.

The conductive fabric electrodes S0a-c can be carried by the sensing covering 30 in accordance with an intended electrode layout, pattern, or spatial configuration that facilitates or enables the detection of physiologic signals from one or more target body regions when portions of a subject’s body are carried or braced by the subject support structure 20. A set of electrodes 50a-c positioned to detect signals associated with a target body region can be considered as defining a target sensing region. The spatial configuration or arrangement of conductive electrodes 50a-c can depend upon a type of subject support structure 20 with which the sensing covering 30 is associated; an expected location of one or more target body regions with respect to particular portions the subject support structure 20; and a set of physiologic parameters of interest that can be determined by way of sensing operations directed to such target body regions.

More particularly, in multiple embodiments the sensing covering 30 can be configured to overlap or overlay a patient support structure 20 such that particular conductive fabric electrodes 50a-c are located at or proximate to a portion of the patient support structure that carries a target patient body region to which sensing or monitoring operations are directed. In a representative embodiment configured for monitoring heart and/or chest related physiologic parameters such as ECG signals, breathing rate, and/or a lung fluid condition, particular conductive fabric electrodes S0a-c can be positioned at a patient support structure location at which the patient’s chest resides or is generally expected to reside. For instance, particular conductive fabric electrodes S0a-c can be positioned between an approximate midpoint and upper quarter section (e.g., at, across, or near an upper third) of a bed’s length, and can span at least approximately 50% (e.g., about 70% - 80%) of the bed’s width. A spatial configuration of conductive fabric electrodes 50a-c such as that shown in FIG. 1 is suitable for monitoring heart and/or chest related physiologic parameters.

In a representative embodiment configured for monitoring renal function, particular conductive fabric electrodes 50a-c can be positioned relative to a subject or patient support structure location at which the subject’s or patient’s kidneys are expected to generally reside. For instance, conductive fabric electrodes 50a-c can be positioned between an approximate midpoint and an upper third of a bed’s length, and can span approximately 20% - 50% (e.g., about 33%) of the bed’s width with respect to a midline along the bed’s length.

In several embodiments, the sensing covering 30 can further include an electrical terminal 80a-c corresponding to each conductive fabric electrode 50a-c. An electrical terminal 80a-c can include one or more conductive elements such as wires, and/or one or more conductive substances such as a conductive paste or glue, which extend into or along a portion of a conductive fabric electrode 50a-c. An electrical terminal 80a-c can further include an attachment element (e.g., an electrical connector, not shown) configured to facilitate or enable electrical signal transfer between the sensing interface unit 100 and a conductive fabric electrode 50a-c by way of an electrical lead 90a-c.

Aspects of Representative Sensing Interface Unit Embodiments

The sensing interface unit 100 can acquire and process electrical signals corresponding to particular conductive fabric electrodes 50a-c, and transfer sampled and/or processed signals or data to the control unit 200. The sensing interface unit 100 can define, establish, or select a sensing configuration that determines a manner in which electrical signals are carried by one or more conductive fabric electrodes 50a-c. The sensing configuration can thus determine a manner in which patient physiologic signals can be detected or monitored. In various embodiments, the sensing configuration can correspond to an active sensing mode or a passive sensing mode. As previously indicated and as further described below, active sensing involves generating an extrinsic electric signal or field, exposing a target body region to the generated electric field, and sensing a manner in which the target body region affects or influences this electric field and/or circuit behavior or parameter associated therewith. Passive sensing involves sensing bioelectric signals that are intrinsically generated within portions of a target body region.

Aspects of a Representative Active Sensing Configuration / Active Sensing Mode

FIG. 2A is a representative illustration of an active sensing configuration according to an embodiment of the disclosure. In an active sensing embodiment, a first electrode 50a and a second electrode 50b can be configured to provide a displacement current path for a time varying or oscillating signal that is generated by a signal generator, excitation source, or oscillator having an output coupled to one of the first and second electrodes 50a-b. The time varying signal generates an electric field between and in the vicinity of the first and second electrodes 50a-b, which are spatially disposed within a target active sensing region 58a at which a patient’s target body region resides or is expected to reside.

When positioned within or proximate to the target active sensing region 58a, the target body region can be considered as a biological impedance load (e.g., a capacitive load) with respect to a circuit that includes the oscillator and the first and second electrodes 50a-b. The presence of the target body region within or near the target active sensing region 58a can thus modify a dielectric property or characteristic between the first and second electrodes 50a-b, thereby affecting, modifying, or modulating aspects of a subject-extrinsic electric field generated using the first and second electrodes 50a-b and/or a circuit parameter corresponding to the first and second electrodes 50a-b. The target body region impedance can change or vary with time, for instance, as a result of a change in target body region volume, fluid content, and/or tissue composition. That is, the target body region can correspond to a changing or time varying bioimpedance. In general, target body region impedance variation can result from one or more periodic, generally periodic, or cyclical biological phenomena (e.g., heart beat or breathing), and/or a periodic or non-periodic transition in tissue state or structure (e.g., an increase or decrease in organ fluid content). As the target body region’s impedance changes or varies with time, the dielectric characteristic between the first and second electrodes 50a- b correspondingly changes or varies with time.

Variations in target body region impedance can affect one or more electrical circuit parameters (e.g., one or both of a current value and a voltage value) and/or a manner in which an oscillatory circuit behaves, for instance, by affecting (e.g., altering, shifting, broadening, destabilizing, or disrupting) an oscillation frequency of the circuit. A given variation in target body region impedance can be correlated with or correspond to a characteristic frequency or frequency range at which a particular physiologic process (e.g., heart rate or respiration rate) occurs within the target body region. Furthermore, distinct physiologic processes can give rise to impedance variations that exhibit distinguishable circuit parameter variations and/or characteristic frequencies.

In accordance with various embodiments of the disclosure, the sensing interface unit 100 and/or the control unit 200 can correlate target body region induced changes in an inter- electrode dielectric characteristic, one or more electrical circuit parameters, and/or an oscillatory circuit behavior with particular types of patient physiologic parameters based upon sampled signal values obtained by way of the first and second electrodes 50a-b.

Additional active sensing configuration details, and representative manners in which the sensing interface unit 100 and/or the control unit 200 can determine, calculate, estimate, and/or evaluate particular patient physiologic parameters obtained by way of active sensing, are further described below.

While FIG. 2A illustrates an oscillator having an output coupled to the second electrode 50b, in an alternate embodiment the oscillator can have an output that is coupled to a third electrode 50c. In such an embodiment, the third electrode 50c can generate an oscillating electric field within the target active sensing region 58a, and the first and/or second electrode 50a-b can be used to sense variations in the oscillating electric field corresponding to physiologic parameters.

Aspects of a Representative Passive Sensing Configuration / Passive Sensing Mode

FIG. 2B is a representative illustration of a passive sensing configuration according to an embodiment of the disclosure. In a passive sensing configuration, a first and a second electrode 50a-b can be configured to detect changes in intrinsic patient bioelectric signals at or proximate to a target passive sensing region 58b, and a third electrode 50c can optionally be configured as a reference electrode. Intrinsic patient bioelectric signals can be generated by physiologic processes such as cardiac activity that give rise to patient generated electric signals or fields. The sensing interface unit 100 and/or the control unit 200 can correlate sensed intrinsic bioelectric signals with particular types of patient physiologic parameters based upon sampled signal values obtained by way of the first and second electrodes 50a-b, as further described in detail below.

Representative Dual-Mode Sensing Interface Unit

FIG. 3A is a schematic block diagram illustrating a sensing interface unit 100 according to an embodiment of the disclosure, which can be selectively configured or programmed to operate in an active sensing mode or a passive sensing mode. In an embodiment, the sensing interface unit 100 includes a differential amplifier 110, a signal acquisition and processing unit 120, an excitation source or oscillatory signal generator 130, a first signal selector 140, an output amplifier 150, and a second signal selector 160.

In the embodiment shown, the differential amplifier 110 is electrically coupled to the first and second electrodes 50a-b. The differential amplifier 110 is configured to detect and amplify a signal difference between the first and second electrodes 50a-b and reject a common mode signal in a manner understood by one of ordinary skill in the art. The differential amplifier provides a corresponding sensed differential signal (e.g., corresponding to a detected or sensed current value or a voltage value) to the signal acquisition and processing unit 110. The signal acquisition and processing unit 120 is configured to acquire and process digital samples of the sensed differential signal, and transfer sampled and/or processed data and possibly sensing status information to the control unit 200. The signal acquisition and processing unit 120 is also configured to control the operation of the excitation source 130, the first signal selector 140, and the second signal selector 160 in accordance with a sensing configuration under consideration.

A) Active Sensing Configuration

In an embodiment corresponding to an active sensing configuration, the signal acquisition and processing unit 120 can control the first and second signal selectors 140, 160 such that an output of the excitation source 130 is coupled to the second electrode 50b. Such coupling can involve the output amplifier 150, in a manner understood by one of ordinary skill in the art. The second electrode 50b can thereby be configured to carry or deliver a time varying or oscillating signal generated by the excitation source 130. The first and second electrodes 50a-b provide a displacement current path that facilitates the application of the oscillating signal to a target body region positioned proximate or adjacent to the first and second electrodes 50a-b.

FIG. 3B is a schematic circuit diagram of an excitation source 150 according to an embodiment of the disclosure. In an embodiment, the excitation source 150 includes a

Wien bridge oscillator, which in a representative implementation utilizes circuit elements such as an operational amplifier, resistors, capacitors, and diodes coupled in the manner shown. Such circuit elements can have corresponding values or approximate values as indicated. In a representative implementation, the excitation source 150 generates a signal having a frequency of approximately 10 — 30 kHz (e.g., a 20 kHz sinusoidal signal), and a peak amplitude of approximately 1 — 30 Vpp (e.g., about 3 Vpp).

B) Passive Sensing Configuration

In an embodiment corresponding to a passive sensing configuration, the signal acquisition and processing unit 120 can control the first and second signal selectors 140, 160 such that a reference input of the signal acquisition and processing unit 120 is coupled to the third electrode 50c. Such reference input coupling to the third electrode 50c can involve the output amplifier 150, in a manner understood by one of ordinary skill in the art. The first and second electrodes 50a-b can detect or electrically respond to bioelectric signals that are generated within a target body region that overlies or which is adjacent or proximate to the first and second electrodes 50a-b.

C) Differential Signal Amplification

In various embodiments, for each of an active sensing configuration and a passive sensing configuration, the differential amplifier 110 can amplify a voltage difference between the first and second electrodes 50a-b, and output a sensed differential signal to the signal acquisition and processing unit 120. In a representative implementation, the differential amplifier 110 can be a a standard instrumentation amplifier such as INAS55 by Texas Instruments (Texas Instruments Incorporated, Dallas, TX USA).

D) Signal Sampling and Initial Processing

The signal acquisition and processing unit 120 includes an analog to digital converter (ADC) that samples the sensed differential signal to generate a time series of digital data values corresponding to sensed physiologic parameter values. In several embodiments, the signal acquisition and processing unit 120 can additionally processes sampled signals ranging from approximately 200 - approximately 5000 samples per second (e.g., 1000 samples per second with digital bandpass filtering).

As indicated above, the signal acquisition and processing unit 120 can be configured to receive commands and/or instructions from the control unit 200. Such commands or instructions can include, for instance, sensing configuration information, or program instructions that define one or more manners in which sensed signals are to be sampled or processed. In a number of embodiments, the signal acquisition and processing unit 120 includes a digital signal processor (DSP). In a representative implementation, the signal acquisition and processing unit 120 includes a digital signal controller (e.g. Freescale

MC56F8006/2 16-bit digital signal controller (Freescale Semiconductor, Inc., Austin,

TX, USA).

Aspects of Representative Control Unit Embodiments

FIG. 4 is a block diagram illustrating a control unit 200 according to an embodiment of the disclosure. In general, the control unit 200 can manage or direct physiologic parameter sensing operations, which can include particular processes described below with reference to FIGs. SA — 8B. In an embodiment, the control unit 200 includes a computer or computing device (e.g., a personal computer or a computer workstation) having a processing unit 210; an input device interface 220 coupled to a set of input devices such as a keyboard 222 and a mouse 224; an output device interface 230 coupled a computer monitor 232 and/or other type of output, presentation, display, or notification device (e.g., a set of speakers or LEDs); a data storage unit 240; a sensing input/output (1/0) unit 250 configured for signal communication with the sensing interface unit 100; a memory 260; and a network interface unit 280, which can be configured for signal communication with a computer network 282 such as the Internet, and/or one or more other types of networks 284, for instance, a local wire-based or wireless network, or a mobile telephone network. In an embodiment, each element of the control unit 200 can be coupled to a common bus 290.

The processing unit 210 includes one or more processors (e.g., at least one microprocessor and/or microcontroller) capable of executing stored program instructions.

The data storage unit 240 includes one or more types of fixed and/or removable data storage devices or elements, as well as storage media corresponding thereto. For instance, the data storage unit 240 can include a hard disk drive, a DVD or CD-ROM drive, and/or a USB flash drive.

The sensing 1/0 unit 250 includes a data transfer interface that operates in accordance with a data transfer standard. Depending upon embodiment details, the sensing I/O unit 250 can be wire-based or wireless. In a representative implementation, the sensing 1/0 unit 250 can include a ZigBee End-Device Module (ZigBee Alliance, www. zighee org).

The memory 260 includes one or more types of volatile and/or nonvolatile memory, such as a register set, Random Access Memory (RAM), and Read Only Memory (ROM).

Portions of the data storage unit 230 and/or the memory 260 can form one or more computer programmable or readable media on which program instructions (e.g., computer or processor readable/executable instructions) directed to acquiring, analyzing, communicating, and/or presenting patient physiologic parameters and/or information, signals, or data relating thereto in accordance with an embodiment of the disclosure reside.

In an embodiment, the memory 260 includes an operating system 262, a sensing control module 270, a sensed parameter memory 272, a parameter analysis module 274, and a parameter communication and/or presentation module 276. Each of the sensing control module 270, the parameter analysis module 274, and the parameter communication / presentation module 276 can include a set of program instructions that is executable by the processing unit 210 to facilitate physiologic or physiologic correlate signal sensing, processing, and presentation operations in accordance with an embodiment of the disclosure.

The sensing control module 270 can include a set of program instructions directed to controlling the operation of the sensing interface unit 100, for instance, to selectively establish a particular sensing configuration and initiate the acquisition of data values corresponding to one or more sensed physiologic parameters at one or more times. The sensing control module 270 can further include a set of program instructions that provide a Graphical User Interface (GUI) that facilitates user identification or selection of one or more physiologic parameters of interest. In certain embodiments, based upon user input or user selections from a graphical menu of physiologic parameters that the system 10 can be configured to sense, the sensing control module 270 can automatically select or define a sensing program or recipe, and transfer configuration and sensing commands to the signal acquisition and processing unit 120 to acquire one or more sets of user identified physiologic parameters. Portions of such a sensing program or recipe can include program instructions configured to manage or direct active or passive sensing operations in accordance with embodiments of the disclosure. In an embodiment, a GUI provided by the sensing control module 270 can additionally define one or more user selectable manners of communicating, presenting, displaying, or outputting sensed physiologic parameters and/or patient related status information, notifications, or alerts.

The sampled parameter memory 272 can include a set of storage locations configured to store sampled data received from the sensing interface unit 100. The parameter analysis module 274 can analyze data values stored in the sampled parameter memory 272, and process such data values to a) generate physiologic parameter values or correlates thereof; b) indicate or determine subject state or condition; and/or ¢) generate numerical or graphical representations corresponding to physiologic parameter values and/or subject state or condition over time. In some embodiments, the parameter communication / presentation module 276 can manage or direct the communication or transfer of physiologic parameter values, physiologic parameter waveforms, and/or subject related status, notification or alert information, signals, data to external systems or devices (e.g., a remote computer system), for instance, by way of communication over the Internet 282 and/or another network 284. Additionally or alternatively, the parameter communication / presentation module 276 can manage or direct the display or output physiologic parameter values, physiologic parameter waveforms, and/or subject related status, notification, or alert information, signals, or data.

Particular manners in which the sensing control module 270, the parameter analysis module 274, and the parameter communication / presentation module 276 can perform physiologic parameter sensing and communication / presentation operations are described in detail hereafter with respect to FIGs. SA — 8B.

Aspects of Representative Physiologic Parameter Sensing Processes

FIG. 5A is a flow diagram of a process 300 for patient monitoring or physiologic parameter sensing according to an embodiment of the disclosure. In an embodiment, the process 300 includes a first process portion 310 that involves determining or selecting a first or next patient physiologic parameter and/or target body region for consideration, and a second process portion 320 that involves determining whether sensed signals corresponding to the physiologic parameter under consideration are to be acquired by way of an active sensing configuration or a passive sensing configuration.

In the event that sensed signals are to be acquired by way of an active sensing configuration, a third process portion 330 can involve applying an oscillating signal to a target body region using the first and second electrodes 50a-b, such that the target body region is exposed to an oscillating electric field produced by way of such electrodes 50a- b.

A fourth process portion 340 can involve detecting and amplifying a difference between a signal carried by the first electrode 50a and a signal carried by the second electrode 50b.

In an active sensing configuration, the detected signal difference corresponds to an extent to or manner in which the target body region affects or perturbs a displacement current between the first and second electrodes 50a-b (e.g., as a result of changing a dielectric characteristic between the first and second electrodes 50a-b in response to a physiologic process within the target body region). In a passive sensing configuration, the detected signal difference corresponds to an electrophysiologic or bioelectric signal that is intrinsically generated within the target body region itself.

A fifth process portion 350 can involve acquiring sampled data values corresponding to a signal difference between the first and second electrodes 50a-b, and a sixth process portion 355 can involve processing the sample data values to generate physiologic parameter or physiologic parameter correlate data. Depending upon embodiment details, the sixth process portion 355 can involve storing raw sampled data, and/or generating smoothed, averaged, or otherwise processed (e.g., filtered) data relative to one or more time periods (e.g., a seconds-based time interval or a minutes-based time interval).

A seventh process portion 360 can involve determining a patient state, generating patient status information, and/or generating one or more notifications or alerts, as further described below with reference to FIG. 5B. An eighth process portion 380 can involve outputting and/or storing or recording physiologic parameter data and information related thereto. For instance, the eighth process portion 380 can involve presenting or displaying physiologic parameter values, waveforms, patient status information, notifications, and/or alerts. Depending upon whether a determined patient state or status corresponds to a desirable or undesirable condition, and the potential or likely seriousness of any undesirable condition, the output of patient status information or the presentation of a notification or alert can include one or more of the display of textual information, the output of audio signals, or the automatic generation and issuance of a set of messages (e.g., one or more e-mail messages, pager messages, and/or Simple Message Service (SMS) messages directed to caretakers or medical personnel). Finally, a ninth process portion 390 can involve determining whether another physiologic parameter and/or another target body region requires consideration; if so, the process 300 can return to the first process portion 310.

FIG. 5B is a flow diagram of a process 360 for determining a patient state and generating patient status information, notifications, and/or alerts according to an embodiment of the disclosure. In an embodiment, the process 360 includes a first process portion 362 that involves retrieving, generating, or updating a set of reference data. The set of reference data can include, for instance, previously generated instantaneous physiologic parameter values, average physiologic parameter values, or one or more physiologic parameter value levels or ranges (e.g., a maximum and a minimum value) corresponding to one or more time periods of interest. Depending upon embodiment details, a time period of interest can be a seconds-based, a minutes-based, or an hours-based time interval; or possibly a longer time interval such as a day-based, a week-based, or a month-based time interval.

A second process portion 364 can involve retrieving or determining one or more comparison or correlation measures by which current or most-recently acquired or generated physiologic parameter data can be evaluated with respect to the reference data.

The comparison or correlation measures can include or define one or more threshold parameter levels (e.g., a minimum or maximum level), a parameter range, a parameter percentage deviation (e.g., a minimum or maximum deviation), or the like in view of a type of physiologic parameter presently under consideration.

A third process portion 366 can involve analyzing the current set of physiologic parameter data with respect to the reference data and/or the comparison or correlation measures, and a fourth process portion 368 can involve determining or estimating a patient state or condition based upon an analysis performed in association with the third process portion 366. Depending upon the behavior of or relationship between current physiologic parameter data under consideration and the reference data and/or a comparison or correlation measure, a patient state can correspond to normal or expected physiologic parameter behavior, or abnormal, unexpected, or pathologic physiologic parameter behavior.

A fifth process portion 370 can involve determining whether a reporting, notification, or alert condition exists in view of an analysis performed in association with the third process portion 366 and any patient state determined in association with the fourth process portion 368. If a reporting, notification, or alert condition exists, a sixth process portion 372 can involve generating patient status, notification, and/or alert information,

where such information can include a patient state indicator (e.g., a patient state message).

Those of ordinary skill in the art will recognize that aspects of one or more process portions described above with reference to FIGs. SA and 5B can be combined / merged, or omitted depending upon embodiment details and/or particular physiologic parameters or target body regions under consideration. Similar considerations apply to aspects of process portions described hereafter with reference to FIGs. 6A — 8B.

FIG. 6A is a flow diagram of a process 400 for acquiring, processing, communicating, and/or presenting information corresponding to patient breathing or respiration according to an embodiment of the disclosure. Such a process 400 can be used to determine whether a patient is experiencing a dysfunctional, abnormal, or undesirable respiratory or breathing condition, or a normal breathing condition relative to one or more time periods of interest. In one embodiment, the process 400 includes a first process portion 410 involving the establishment of an active sensing configuration with respect to a target sensing region that includes portions of the patient’s chest or upper body, and a second process portion 420 involving the generation of an oscillating signal which is applied to an electrode (e.g., electrode 50a) proximate to the chest. A sensing electrode (e.g., electrode 50b) also proximate to the chest detects and amplifies the received signal in a third process portion 430. A fourth process portion 440 samples and digitizes the detected signal(s), for instance, to generate a waveform that includes or corresponds to breathing pattern information, after which a fifth process 450 applies signal processing algorithms to detect or determine a breathing pattern or rhythm. A sixth process portion 460 correlates the determined breathing pattern or thythm to a normal or a dysfunctional breathing condition such as sleep apnea or an asthma attack, and correspondingly generates one or more of a patient state indicator, patient status information, a notification, and/or an alert as appropriate (e.g., based upon whether the breathing pattern is normal or abnormal). Finally, a seventh process portion 470 stores and/or outputs (e.g., communicates, displays, or otherwise presents) the processed measurements and any relevant patient status information, notification(s), and alert(s).

FIG. 6B is a graph illustrating a representative waveform 490 that includes or corresponds to breathing pattern information for a normal subject in accordance with an embodiment of the disclosure. Such a representative waveform can be detected or generated by embodiments of the present disclosure. Deviations from a normal breathing pattern waveform would indicate dysfunctional breathing aspects corresponding to a disorder such as sleep apnea, an asthma attack, or another breathing related condition.

The detected waveform of FIG. 6B includes both breathing pattern information as well as patient body movement information, i.e., subject breathing pattern data is superimposed upon subject body movement data.

FIG. 7A is a flow diagram of an embodiment of a process 500 for acquiring, processing, communicating, and/or presenting information corresponding to a target body region fluid state according to an embodiment of the disclosure. Such a process 500 can be used to determine whether a patient is experiencing a pathological or a normal fluid condition corresponding to an organ or tissue within a target body region to which sensing operations are directed. In one embodiment, the process 500 includes a first process portion 510 involving the establishment of an active sensing configuration with respect to a target sensing region that includes portions of the patient’s chest and abdomen, and a second process portion 520 involving the generation of an oscillating signal which is applied to one or more electrodes 50a-b proximate to the chest and abdomen. A set of sensing electrodes 50a-b also proximate to the chest and abdomen detects and amplifies the received signals in a third second process portion 530. A fourth process portion 540 samples and digitizes the detected signals upon which a fifth process portion 550 applies signal processing algorithms to detect a change in signal strengthen as compared to a set of previous measures. A sixth process portion 560 determines or generates a corresponding patient state indicator and patient status information, a notification, or an alert if relevant. A seventh process 570 stores and/or outputs (e.g., communicates, displays, or otherwise presents) the processed measurements and any relevant patient status information, notification(s), and alert(s).

FIG. 7B is a graph illustrating a representative set of fluid state measurements 590 over time corresponding to a target body region in accordance with an embodiment of the present disclosure. In an embodiment, the representative set of fluid state measurements 590 can indicate physiologic dysfunction corresponding to renal failure and the consequent onset of oedema. In other embodiments, a set of fluid state measurements can indicate physiologic dysfunction corresponding to another organ. As indicated in

FIG. 7B, a detected voltage level corresponding to organ failure (e.g., renal failure) and the onset of oedema differs from (e.g., is greater than) a voltage level corresponding to normal physiologic state. In response to a change or shift in a detected voltage level, for instance, a voltage level shift that differs from a baseline voltage level by approximately 5% - 10% or more, embodiments of the disclosure can generate and communicate and/or store an appropriate patient state indicator, patient status information, a notification, and/or an alert. The magnitude of a voltage level change or shift that gives rise to the generation of a patient state indicator or a notification / alert can depend upon an organ under consideration (e.g., the lungs, versus the kidneys).

FIG. 8A is a flow diagram of a process 600 for acquiring, processing, communicating, and/or presenting information corresponding to patient cardiac parameters according to an embodiment of the disclosure. Such a process 600 can be used to determine or evaluate a cardiac related physiologic parameter. In an embodiment 600, the process 600 includes a first process portion 610 that involves establishing a passive sensing configuration with respect to a target sensing region that includes a portion of the patient’s chest that is at least proximate to the heart. A second process portion 630 involves the use of conductive fabric electrodes 50a-b for the sensing and differential amplification of weak signals generated by the heart during cardiac depolarization and repolarisation from electrodes which are proximate to the heart. A third process portion 640 samples and digitizes the signal, upon which a fourth process portion 650 applies signal processing algorithms to detect the heart rate and rhythm. A fifth process portion 660 determines or generates a patient state indicator and any patient status information, a notification, or an alert if relevant. The fifth process portion 660 can involve correlating the processed measurements them to cardiac related parameters such as indicators of pathological disorders of the heart. Finally, a sixth process portion 670 stores and/or outputs (e.g., communicates, displays, or otherwise presents) the processed measurements and any relevant patient status information, notification(s), and alert(s).

FIG. 8B is a graph illustrating a representative cardiac waveform or pattern 690 that can be detected by embodiments of the disclosure. Such a cardiac waveform 690 can indicate or include aspects of normal cardiac activity and/or abnormal or dysfunctional cardiac activity that can correspond to or result from a condition or disorder such as arrhythmia, tachycardia, bradycardia, irregular cardiac rhythm, atrial fibrillation, or myocardial infarction. The representative cardiac waveform 690 of FIG. 8B corresponds to a normal heart rate pattern, and indicates the cardiac sinus rhythm, including mild variations of instantaneous heart rate corresponding to the subject’s breathing state. Embodiments of the disclosure can analyze or evaluate sampled data corresponding to a cardiac waveform 690, and generate and communicate and/or store an appropriate patient state indicator, patient status information, a notification, and/or an alert in the event that aspects of the cardiac waveform 690 correspond to abnormal or pathological cardiac function.

Particular embodiments of the disclosure are described above for addressing at least one of the previously indicated problems. While features, functions, advantages, and alternatives associated with certain embodiments have been described within the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the disclosure. For instance, certain embodiments can include one or more conductive fabric electrodes, as well as a plate or other type of electrode that is capacitively couplable to the patient (e.g., a plate electrode that is carried by a portion of a table, and positioned beneath a sheet or other type of covering). Additionally or alternatively, certain embodiments can include both conductive fabric electrodes as well as conventional electrodes that detect or deliver electrical signals by way of conduction current. It will be appreciated that several of the above-disclosed and other structures, features and functions, or alternatives thereof, may be desirably combined into other different devices,

systems, or applications.

The above-disclosed structures, features and functions, or alternatives thereof, as well as various presently unforeseen or unanticipated alternatives, modifications, variations or improvements thereto that may be subsequently made by one of ordinary skill in the art, are encompassed by the following claims.

Claims (48)

Claims

1. A method for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body, the method comprising: coupling a plurality of electrodes to an excitation source; generating a subject-extrinsic time varying electrical signal using the excitation source; generating a subject-extrinsic time varying electric field using the plurality of electrodes; exposing the portion of the subject’s body to the subject-extrinsic time varying electric field; and detecting a manner in which the portion of the subject’s body affects the subject- extrinsic time varying electric field, wherein at least one electrode within the plurality of electrodes comprises a conductive fabric electrode.

2. The method of claim 1, wherein detecting a manner in which the portion of the subject’s body affects the subject-extrinsic time varying electric field comprises detecting a circuit parameter corresponding to a first electrode and a second electrode within the plurality of electrodes.

3. The method of claim 2, wherein the circuit parameter comprises one of an electrical current parameter and a voltage parameter.

4. The method of claim 1, wherein the manner in which the portion of the subject’s body affects the subject-extrinsic time varying electric field is correlated with a time varying dielectric characteristic corresponding to the portion of the subject’s body.

5. The method of claim 1, further comprising capacitively coupling the conductive fabric electrode to the portion of the subject’s body.

6. The method of claim 1, wherein the portion of the subject’s body and the conductive fabric electrode are substantially freely movable relative to each other.

7. The method of claim 1, wherein the plurality of electrodes comprises a first conductive fabric electrode and a second conductive fabric electrode.

8. The method of claim 7, further comprising capacitively coupling each of the first conductive fabric electrode and the second conductive fabric electrode to the portion of the subject’s body.

9. The method of claim 7, wherein the portion of the subject’s body is substantially freely movable with respect to each of the first conductive fabric electrode and the second conductive fabric electrode.

10. The method of claim 1, wherein the excitation source comprises an oscillator.

11. A method for acquiring and processing signals correlated with a physiologic state of a first portion of a subject’s body, the method comprising: providing a first electrode and a second electrode, at least one of the first electrode and the second electrode comprising a conductive fabric electrode; identifying a first physiologic parameter to be detected; determining whether the first physiologic parameter is detectable by way of an active sensing configuration that involves exposing the first portion of the subject’s body to a subject-extrinsic time varying electric field or a passive sensing configuration that avoids exposing the first portion of the subject’s body to the subject-extrinsic time varying electric field; and selectively (a) coupling each of the first electrode and the second electrode to an excitation source; or (b) isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the first physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration.

12. The method of claim 11, wherein coupling each of the first electrode and the second electrode to the excitation source comprises automatically coupling one of the first electrode and the second electrode to the excitation source.

13. The method of claim 11, further comprising: capacitively coupling the first electrode and the second electrode to the first portion of the subject’s body; and generating a differential signal corresponding to a signal difference between the first electrode and the second electrode.

14. The method of claim 13, wherein the differential signal corresponds to a subject- intrinsic electrical signal detected using the first electrode and the second electrode.

15. The method of claim 13, wherein the differential signal is correlated with a time varying dielectric characteristic corresponding to the first portion of the subject’s body.

16. The method of claim 15, wherein the differential signal is correlated with a manner in which the time varying dielectric characteristic affects the subject-extrinsic time varying electric field.

17. The method of claim 13, further comprising storing sampled data corresponding to the differential signal.

18. The method of claim 13, further comprising processing sampled data corresponding to the differential signal to generate a representation of the first physiologic parameter.

19. The method of claim 13, further comprising: generating a subject-extrinsic time varying electrical signal using the excitation source;

generating the subject-extrinsic time varying electric field using the first electrode and the second electrode; and detecting a manner in which the first portion of the subject’s body affects the subject- extrinsic time varying electric field.

20. The method of claim 19, wherein detecting a manner in which the first portion of the subject’s body affects the subject-extrinsic time varying electric field comprises detecting an electrical circuit parameter corresponding to the first electrode and the second electrode.

21. The method of claim 20, wherein the circuit parameter comprises one of an electrical current parameter and a voltage parameter.

22. The method of claim 19, wherein detecting a manner in which the first portion of the subject’s body affects the subject-extrinsic time varying electric field comprises detecting a manner in which a time varying dielectric characteristic corresponding to the first portion of the subject’s body affects the subject-extrinsic time varying electric field.

23. The method of claim 11, wherein the excitation source comprises an oscillator.

24. The method of claim 11, further comprising communicating at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network.

25. The method of claim 11, further comprising displaying at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert on a display device.

26. The method of claim 11, wherein the first physiologic parameter corresponds to one of a fluid state, a breathing related parameter, a motion related parameter, and a cardiac parameter of the subject.

27. The method of claim 11, further comprising: identifying a second physiologic parameter to be sensed, the second physiologic parameter distinguishable from the first physiologic parameter; determining whether the second physiologic parameter is detectable by way of an active sensing configuration that involves exposing a second portion of the subject’s body to the time varying subject-extrinsic electric field or a passive sensing configuration that avoids exposing the second portion of the subject’s body to the time varying subject-extrinsic electric field; and selectively (a) coupling each of the first electrode and the second electrode to the excitation source; or (b) isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the second physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration.

28. The method of claim 27, wherein the first portion of the subject’s body and the second portion of the subject’s body are at least substantially identical.

29. The method of claim 27, wherein the second portion of the subject’s body is at least substantially different than the first portion of the subject’s body.

30. The method of claim 27, further comprising: detecting a first set of signals corresponding to the first physiologic parameter by way of an active sensing configuration; and detecting a second set of signals corresponding to the second physiologic parameter by way of a passive sensing configuration.

31. A system for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body, the system comprising: a first electrode; a second electrode; an excitation source configured to generate a subject-extrinsic time varying electric signal; a sensing interface unit configured to selectively establish (a) an active sensing configuration in which each of the first electrode and the second electrode is coupled to the excitation source; and (b) a passive sensing in which each of the first electrode and the second electrode is electrically isolated from the excitation source; and a signal acquisition unit coupled to the first electrode and the second electrode and configured to generate sampled data corresponding to a set of signals carried by the set of electrodes, wherein at least one of the first electrode and the second electrode comprises a conductive fabric electrode.

32. The system of claim 31, wherein each of the first electrode and the second electrode comprises a conductive fabric electrode.

33. The system of claim 31, wherein each of the first electrode and the second electrode is capacitively coupled to the portion of the subject’s body.

34. The system of claim 31, further comprising a subject support structure that carries the set of electrodes.

35. The system of claim 34, wherein the subject support structure comprises one of a bed, a table, a chair, and an animal enclosure.

36. The system of claim 31, further comprising one from the group of a covering and a bedding material configured to carry the conductive fabric electrode.

37. The system of claim 31, wherein the excitation source comprises an oscillator.

38. The system of claim 31, further comprising a control unit coupled to the sensing interface unit, the control unit comprising: a memory configured to store sampled data; and a processing unit configured to process sampled data.

39. The system of claim 38, wherein the control unit further comprises a sensing control module configured to selectively direct the sensing interface unit to establish an active sensing configuration or a passive sensing configuration.

40. The system of claim 39, wherein the control unit directs the sensing control module to establish an active sensing configuration or a passive sensing configuration based upon user input corresponding to user identification of a physiologic parameter.

41. The system of claim 39, wherein the control unit further comprises a parameter analysis module configured to process sampled data in accordance with a physiologic parameter under consideration.

42. The system of claim 39, wherein the control module further comprises a parameter communication module configured to communicate at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network.

43. The system of claim 39, wherein the control unit further comprises a parameter presentation module configured to direct the display of at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert.

44. A computer readable medium storing program instructions configured to direct operations performed by a system for acquiring and processing signals correlated with a physiologic state of a portion of a subject’s body, the system comprising a first electrode and a second electrode capacitively couplable to the subject, a sensing control and interface unit, an excitation source configured to generate a subject-extrinsic time varying electrical signal, and a control unit comprising a processor and a memory, at least one of the first electrode and the second electrode comprising a conductive fabric electrode, the program instructions when executed causing the system to: identify a first physiologic parameter of the subject to be detected; determine whether the first physiologic parameter is detectable by way of an active sensing configuration that involves an application of a subject-extrinsic time varying electric field to the portion of the patient’s body or a passive sensing configuration that avoids the application of a subject-extrinsic time varying electric field to the portion of the patient’s body; and selectively (a) couple the first electrode and the second electrode to the excitation source; or (b) electrically isolate each of the first electrode and the second electrode from the excitation source based upon determining whether the first physiologic parameter is detectable by way of an active sensing configuration or a passive sensing configuration.

45. The computer readable medium of claim 44, wherein the first physiologic parameter corresponds to one of a fluid state, a breathing related parameter, a motion related parameter, and a cardiac parameter of the subject.

46. The computer readable medium of claim 44, further comprising program instructions that when executed cause the system to communicate at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert over a communication network.

47. The computer readable medium of claim 44, further comprising program instructions that when executed cause the system to display at least one of a physiologic parameter value, a physiologic parameter waveform, subject related status information, a subject related notification, and a subject related alert.

48. The computer readable medium of claim 44, further comprising program instructions that when executed cause the system to: identify a second physiologic parameter to be sensed, the second physiologic parameter distinguishable from the first physiologic parameter; determine whether the second physiologic parameter is detectable by way of an active sensing configuration that involves an application of a subject-extrinsic time varying electric field to the portion of the patient’s body or a passive sensing configuration that avoids the application of a subject-extrinsic time varying electric field to the portion of the patient’s body; and selectively (a) coupling the first electrode and the second electrode to the excitation source; or (b) electrically isolating each of the first electrode and the second electrode from the excitation source based upon determining whether the second physiologic parameter corresponds to an active sensing configuration or a passive sensing configuration.