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COMMUNICATIONS NETWORK FOR
DISTRIBUTED SENSING AND THERAPY IN
CROSS REFERENCE TO PRIORITY 5
This application claims priority to application Ser. No. 60/805,787, filed Jun. 26, 2006 and entitled, "Communications Network for Distributed Sensing and Therapy in Bio- 10 medical Applications", which is incorporated by reference herein.
REFERENCE TO RELATED APPLICATIONS
Reference is made to commonly assigned application 60/805,789 entitled "LOCAL COMMUNICATIONS NETWORK FOR DISTRIBUTED SENSING AND THERAPY IN BIOMEDICAL APPLICATIONS", having which is filed 20 on even date with the present application and hereby incorporated herein by reference in its entirety.
The invention relates generally to implantable medical device systems and, in particular, to a communications network for use with implantable sensing and/or therapy delivery devices organized in a distributed, mesh network.
A wide variety of implantable medical devices (IMDs) are available for monitoring physiological conditions and/or delivering therapies. Such devices may includes sensors for 35 monitoring physiological signals for diagnostic purposes, monitoring disease progression, or controlling and optimizing therapy delivery. Examples of implantable monitoring devices include hemodynamic monitors, ECG monitors, and glucose monitors. Examples of therapy delivery devices include devices enabled to deliver electrical stimulation pulses such as cardiac pacemakers, implantable cardioverter defibrillators, neurostimulators, and neuromuscular stimulators, and drug delivery devices, such as insulin pumps, mor- 45 phine pumps, etc.
IMDs are often coupled to medical leads, extending from a housing enclosing the IMD circuitry. The leads carry sensors and/or electrodes and are used to dispose the sensors/electrodes at a targeted monitoring or therapy delivery site while 50 providing electrical connection between the sensor/electrodes and the IMD circuitry. Leadless IMDs have also been described which incorporate electrodes/sensors on or in the housing of the device.
IMD function and overall patient care may be enhanced by 55 including sensors distributed to body locations that are remote from the IMD. However, physical connection of sensors distributed in other body locations to the IMD in order to enable communication of sensed signals to be transferred to the IMD can be cumbersome, highly invasive, or simply not 60 feasible depending on sensor implant location. An acoustic body bus has been disclosed by Funke (U.S. Pat. No. 5,113, 859) to allow wireless bidirectional communication through a patient's body. As implantable device technology advances, and the ability to continuously and remotely provide total 65 patient management care expands, there is an apparent need for providing efficient communication between implanted
medical devices distributed through a patient's body or regions of a patient's body, as well as with devices.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a wireless communication network implemented in an implantable medical device system.
FIG. 2 is a schematic diagram of one example of a mesh communication network including multiple implantable medical devices.
FIG. 3 is a conceptual diagram depicting the specialized roles that may be assigned to network nodes.
FIG. 4 is a flow diagram providing an overview of the general operation of a mesh network implemented in an implantable medical device system.
FIG. 5 is a conceptual diagram of a mesh network architecture implemented in an implantable medical device system.
FIG. 6 is a conceptual diagram of a channel plan implemented by the mesh network.
The present invention is directed to providing a communications network implemented in an implantable medical device system, wherein the network is configured as a mesh network that allows data to be routed between implanted and external devices as needed via continuously available connections established through node-to-node routes that can include multiple node "hops." In the following description, references are made to illustrative embodiments for carrying out the invention. It is understood that other embodiments may be utilized without departing from the scope of the invention. For purposes of clarity, the same reference numbers are used in the drawings to identify similar elements. As used herein, the term "module" refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, or other suitable components that provide the described functionality.
As used herein, the term "node" refers to a device included in a wireless mesh network capable of at least transmitting data on the network and may additionally include other functions as will be described herein. Each "node" is a "network member" and these terms are used interchangeably herein. A node can be either an implanted or an external device. The wireless mesh network generally includes multiple implantable devices each functioning as individual network nodes in a mesh architecture and may include external devices functioning as equal network nodes as will be further described herein. It is recognized that an overall medical device system implementing a mesh communication network may further include non-networked devices (implantable or external).
FIG. 1 is a schematic diagram of a wireless communication network implemented in an implantable medical device system. The wireless communication network is characterized by a mesh architecture that allows multi-hop communication across network nodes. The network includes multiple implantable devices 12 through 26 each functioning as a node (network member). The network may further include external devices functioning as equal nodes. Patient 10 is implanted with multiple medical devices 12 through 26 each of which may include physiological sensing capabilities and/or therapy delivery capabilities. As will be further described herein, some of the implanted devices 12 through 26 may be
implemented as specialty nodes for performing specific network functions such as data processing, data storage, or communication management functions without providing any physiological sensing or therapy delivery functions.
For example, device 12 may be a therapy delivery device 5 such as a cardiac pacemaker, implantable cardioverter defibrillator, implantable drug pump, or neurostimulator. Device 16 may also be a therapy delivery device serving as a two-way communication node and may further be enabled for performing specialty network management functions such as 10 acting as a network gateway. Device 14 may be embodied as a sensing device for monitoring a physiological condition and also serve as a two-way communicationnode. Devices 18,22, 24, and 26 may be embodied as sensing devices for monitor- 15 ing various physiological conditions and may be implemented as low-power devices operating primarily as transmitting devices with no or limited receiving capabilities. Device 20 may be implemented as a repeater node for relieving the power requirement burden of sensing device 18 for 20 transmitting data from a more remote implant location to other network nodes. The mesh network is an n-dimensional network wherein node depth may be defined spatially with respect to proximity to a specialized node, such as a node incorporating gateway, data processing or data storage capa- 25 bilities.
Implantable devices that may be included as mesh network members include any therapy delivery devices, such as those listed above, and any physiological sensing devices such as EGM/ECG sensors, hemodynamic monitors, pressure sen- 30 sors, blood or tissue chemistry sensors such as oxygen sensors, pH sensors, glucose sensors, potassium or other electrolyte sensors, or sensors for determining various protein or enzyme levels. The mesh network communication system provided by various embodiments of the present invention is 35 not limited to any specific type or combination of implantable medical devices.
The mesh network communication system allows a multiplicity of devices to be implanted in a patient as dictated by anatomical, physiological and clinical need, without 40 restraints associated with leads or other hardwire connections through the body for communicating signals and data from one device to another. As such, sensors and/or therapy delivery devices may be implanted in a distributed manner throughout the body according to individual patient need for 45 diagnostic, monitoring, and disease management purposes. Data from the distributed system of implanted sensors and/or therapy delivery devices is reliably and efficiently transmitted between the implanted devices for patient monitoring and therapy delivery functions and may be transmitted to external 50 devices as well for providing patient feedback, remote patient monitoring etc.
The implanted devices 12 through 26 may rely on various power sources including batteries, storage cells such as capacitors or rechargeable batteries, or power harvesting 55 devices relying for example on piezoelectric, thermoelectric or magnetoelectric generation of power. The mesh network allows management of communication operations to be performed in a way that minimizes the power burden on individual devices (nodes) and can eliminate functional redun- 60 dancies within the overall system. The distributed devices can be provided having minimal power requirements and thus reduced overall size. Implantable devices functioning as network nodes may be miniaturized devices such as small injectable devices, devices implanted using minimimally invasive 65 techniques or mini-incisions, or larger devices implanted using a more open approach.
The mesh network may include external devices as shown in FIG. 1 such as a home monitor 30, a handheld device 34, and external monitoring device 36. Reference is made to commonly-assigned U.S. Pat. No. 6,249,703 (Stanton e al.) regarding a handheld device for use with an implantable medical device, hereby incorporated herein by reference in its entirety. The medical device system may further include external devices or systems in wireless or wired communication with external mesh networked devices such as a patient information display 32 for displaying data retrieved from the mesh network to the patient, and a remote patient management system 40. Physiological and device-related data is available to any device (node) included in the mesh network, and aggregated data can be used to provide short-loop feedback to the patient or caregiver via the home monitor 30 and patient information display 32. The home monitor 30, in this illustrative example, includes RF receiver and long range network functionality allowing data received from the implanted network nodes to be accumulated and prioritized for further transmission to the remote patient management system 40 and/or patient information display 32. The patient can respond appropriately to information retrieved from the mesh network and displayed on patient information display 32 in accordance with clinician instructions. A patient may respond, for example, by modifying physical activity, seeking medical attention, altering a drug therapy, or utilizing the handheld device 34 to initiate implanted device functions.
Data can also be made available to clinicians, caregivers, emergency responders, clinical databases, etc. via external or parallel communication networks to enable appropriate and prompt responses to be made to changing patient conditions or disease states. Aggregated data can be filtered, prioritized or otherwise adjusted in accordance with patient condition and therapy status to provide clinically meaningful and useful information to a clinician or remote patient management system in a readily-interpretable manner. The home monitor 30 may function as a network administration node receiving patient and device-related data from the implanted nodes in a continuous, periodic, or triggered manner and managing transmissions of the aggregated data to other networks or devices. Reference is made to commonly-assigned U.S. Pat. Nos. 6,599,250 (Webb et al.), 6,442,433 (Linberg et al.) 6,622,045 (Snell et al.), 6,418,346 (Nelson et al.), and 6,480, 745 (Nelson et al.) for general descriptions of network communication systems for use with implantable medical devices for remote patient monitoring and device programming, all of which are hereby incorporated herein by reference in their entirety.
Home monitor 30 and/or a programmer may be used for communicating with one or more of implanted devices 12 through 26 using bidirectional RF telemetry for programming and/or interrogating operations. Reference is made to commonly-assigned U.S. Pat. No. 6,482,154 (Haubrich et al.), hereby incorporated herein by reference in its entirety, for an example of one appropriate long-range telemetry system for use with implantable medical devices.
The mesh architecture allows network communication between nodes to make multiple hops. Communication paths between nodes illustrated in FIG. 1 are only examples of some of the shortest pathways existing between adjacent nodes. Communication paths will exist between each node and every other node in the network. Multiple hops may be made between nodes, in accordance with individual node roles, node power status, channel plan and routing scheme, each of which will be further described herein.
The mesh network is a self-configuring network in which all nodes are initially equal status, i.e. the nodes do not func