US20080004663A1 - Defibrillator with implantable medical device detection - Google Patents

Abstract

In general, the invention is directed to techniques for using an external defibrillator to detect a presence of an implantable medical device (IMD) implanted within a patient, and providing therapy to the patient through communication between the external defibrillator and the IMD. An external defibrillator provides prompts to a user of the external defibrillator to determine the presence of an IMD implanted within the patient. For example, the external defibrillator may prompt the user to visually inspect the patient's chest for signs that an IMD was implanted, such as a scar or raised portion of skin near the patient's clavicles. As another example, the external defibrillator may prompt the user to place a detection device on the patient's chest. The detection device may be coupled to the external defibrillator, and may employ a magnet to initiate telemetry by the IMD to detect the presence of the IMD.

Description

TECHNICAL FIELD
• The invention relates to emergency medical devices and, more particularly, to external defibrillators.
BACKGROUND
• An external defibrillator delivers energy to a heart of a patient via electrodes placed upon the patient's chest. External defibrillators are used to deliver energy in the form of a defibrillation shock to a heart that is undergoing ventricular fibrillation and has lost its ability to contract. Ventricular fibrillation is particularly life threatening because activity within the ventricles of the heart is so uncoordinated that virtually no pumping of blood takes place. If untreated, a patient suffering from fibrillation may die within a matter of minutes.
• An electric shock delivered to a fibrillating heart may depolarize the heart and cause it to reestablish a normal sinus rhythm. In some cases, the patient may need multiple shocks, and the external defibrillator may deliver different quantities of energy with each defibrillation shock. Further, the defibrillator may provide additional or alternative therapies to the patient, such as cardioversion or pacing therapy. As examples, the external defibrillator may be an automated external defibrillator (AED) used by a first responder or bystander to treat the patient, or a more fully-featured defibrillator/monitor used by paramedics.
SUMMARY
• In general, the invention is directed to an external defibrillator equipped to aid a user in detecting the presence of an implantable medical device (IMD) within a patient. Upon detection of an IMD, the external defibrillator may communicate with the IMD to obtain useful information or coordinate delivery of therapy to the patient. As examples, the external defibrillator may receive patient or therapy information from the IMD, prompt a user based on information received from the IMD, deliver therapy based on information received from the IMD, control delivery of therapy by the IMD, and store information within the IMD. Alternatively, or additionally, detection of IMD location may permit the user to place defibrillation electrodes in a location which will reduce the chance of damage to the IMD while still providing effective defibrillation therapy to the patient.
• The external defibrillator may provide prompts to guide a user of the external defibrillator in detecting the presence of an IMD implanted within the patient. For example, the external defibrillator may prompt the user to visually inspect the patient's chest for signs that an IMD was implanted, such as a scar or raised portion of skin near the patient's clavicles. As another example, the external defibrillator may prompt the user to place a detection device on the patient's chest. The detection device may be coupled to the external defibrillator, and may employ a detector to locate an IMD. When an IMD is detected, the external defibrillator or detection device may emit a notification. For example, the detection device may have an audible or visual indicator that assists the user in positioning the detection device.
• The external defibrillator may obtain information from a detected IMD or coordinate delivery of therapy with the IMD by wireless telemetry. For example, the detection device may be integrated with wireless telemetry circuitry to facilitate communication with the IMD. In some embodiments, the detection device may include an adhesive interface to permit adhesive fixation of the detection device at the IMD location, thereby promoting more reliable telemetry. The external defibrillator may deliver therapy based on information received from the IMD in the patient. The external defibrillator may select an energy level for a defibrillation shock to be delivered to the patient based on an energy level of a defibrillation shock previously delivered to the patient by the IMD. As another example, the external defibrillator may analyze an electrogram (EGM) or electrocardiogram (ECG), or output received from the IMD indicating pace, shock or sense events, to determine whether to deliver a defibrillation shock to the patient.
• In one embodiment, the invention provides an external defibrillator comprising a defibrillation therapy generator, electrodes coupled to the defibrillation therapy generator, and a user interface that presents one or more prompts to a user of the external defibrillator to detect presence of an implantable medical device (IMD) in a patient.
• In another embodiment, the invention provides a method comprising generating one or more prompts to a user of an external defibrillator to detect presence of an implantable medical device (IMD) in a patient.
• In an additional embodiment, the invention provides an external defibrillator comprising a defibrillation therapy generator, electrodes coupled to the defibrillation therapy generator, and a detection device that detects presence of an implantable medical device (IMD) in a patient.
• In another embodiment, the invention provides a method comprising detecting presence of an implantable medical device (IMD) in a patient via a detection device associated with an external defibrillator, and indicating presence of the IMD to a user of the external defibrillator.
• In various embodiments, the invention may provide one or more advantages. For example, prompts delivered by an external defibrillator may permit a user to more readily detect the presence and location of an IMD. Upon detection of the IMD location, a user can place defibrillation electrodes at a location which will reduce the chance of damage to the IMD while still providing effective defibrillation therapy to the patient. In addition, a detection device may facilitate rapid detection of the IMD, which promotes timely delivery of therapy. With the ability to communicate with a detected IMD, an external defibrillator may provide more effective treatment to a patient in which the IMD is implanted, permitting coordinated delivery of therapy. In addition, by communication with the IMD, the external defibrillator may more effectively obtain and manage medical information such as patient information or therapy information.
• The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a conceptual diagram illustrating an external defibrillator providing a user prompt for locating an IMD implanted within a patient.
• FIG. 2 is a conceptual diagram illustrating an external defibrillator providing a second user prompt for locating an IMD implanted within a patient.
• FIG. 3 is a conceptual diagram illustrating an external defibrillator providing a third user prompt for locating an IMD implanted within a patient.
• FIG. 4 is a conceptual diagram illustrating an external defibrillator providing a user prompt for placing defibrillation electrodes on a patient.
• FIG. 5 is a block diagram illustrating example components of the external defibrillator ofFIG. 1.
• FIG. 6 is a flowchart illustrating exemplary operation of an external defibrillator.
• FIG. 7 is a block diagram illustrating example components of an IMD detection device for use with the external defibrillator ofFIG. 1.
• FIG. 8 is a block diagram illustrating an example IMD detection device that includes an adhesive layer and a removable backing layer.
• FIG. 9 is a conceptual diagram illustrating an example system that includes an external defibrillator communicating with an IMD implanted within a patient.
DETAILED DESCRIPTION
• FIG. 1 is a conceptual diagram illustrating anexample system10 that includes anexternal defibrillator12 providing auser prompt34 for locating an implantablemedical device14 implanted within apatient16.External defibrillator12 may be brought topatient16 in response to a medicalemergency involving patient16, such as a ventricular fibrillation (VF) or sudden cardiac arrest (SCA) experienced by the patient.External defibrillator12 may be, for example, an automated external defibrillator (AED), or a more fully featured external defibrillator/monitor, such as those used by paramedics or other medical professional. However, the generation of user prompts may be especially useful to a user of an AED. An AED provides basic life support (BLS) services. A more fully featured external defibrillator/monitor may provide advanced life support (ALS) services.
• In the illustrated example,external defibrillator12 is coupled to twoelectrodes18A and18B (collectively “electrodes18”) that are applied to the skin ofpatient16. Electrodes18 may be electrodes pads, which may include an adhesive backing for attachment to the skin ofpatient16, as is known in the art. Electrodes18 are coupled todefibrillator12 by respective leads orcables20A and20B (collectively “cables20”). Although illustrated inFIG. 1 as coupled to two electrodes18,external defibrillator12 may be coupled to any number of electrodes18, which may be incorporated into common electrode pads, and may share common cables20.External defibrillator12 may additionally include one or more sensors (not shown inFIG. 1), such as blood oxygen saturation or noninvasive blood pressure sensors.
• External defibrillator12 detects electrical activity of theheart22 ofpatient16 via electrodes18, and delivers electrical stimulation toheart22 via electrodes18. For example,defibrillator12 may deliver one or more defibrillation shocks topatient16 via electrodes18. As shown inFIG. 1,defibrillator12 may include adisplay24, and may provide instructions in the form of visual prompts and other information to a user via the display.External defibrillator12 may, for example, display an electrocardiogram generated based on the electrical activity detected by electrodes18 viadisplay24. In some embodiments, as mentioned above,defibrillator12 may be coupled to additional sensors for sensing other physiological parameters ofpatient16, such as blood pressure and oxygen saturation, and may display current or average values for the additional parameters viadisplay24.External defibrillator12 may also include aspeaker32 to provide audible user prompts.
• In the illustrated example,IMD14 is a multi-chamber cardiac pacemaker coupled to leads26A-26C (collectively “leads26”) that extend to selected positions withinheart22, such as the right atrium, right ventricle, and left ventricle. As an alternative or in addition to pacing pulses,IMD14 may deliver cardioversion and/or defibrillation shocks toheart22 via leads26. Hence,IMD14 may be an implantable cardioverter-defibrillator (ICD), as is known in the art. Further,IMD14 may sense electrical activity ofheart22 via leads26.
• Leads26 may include any of a variety of types of electrodes (not shown) known in the art for use in sensing cardiac electrical activity and delivering these types of stimulation toheart22. The number and positions of leads26 depicted inFIG. 1 are merely exemplary. Further, the invention is not limited tosystems10 in which an IMD is a pacemaker.IMD14 may be any type of IMD that senses one or more physiological parameters ofpatient16 and/or delivers one or more therapies to the patient. For example,IMD14 may be an implantable neurostimulator, muscle stimulator, gastrointestinal stimulator, an implantable pump, or an implantable monitor such as an implantable loop recorder.
• In the example ofFIG. 1,external defibrillator12 provides auser prompt34 to aid a user in locating an IMD implanted withinpatient16. User prompt34 may be an audible prompt provided viaspeaker32. Alternatively, user prompt34 may be a visual prompt such as a text prompt, pictorial prompt, or other visual prompt. In some embodiments,defibrillator12 may provide both audible and visual prompts.External defibrillator12 may prompt the user to visually inspect an area of the patient's body, e.g., the patient's chest or abdomen for signs that an IMD was implanted inpatient16. Where the patient is a child, an IMD may be implanted in the patient's abdomen. User prompt34 prompts a user to look for a scar near the patient's clavicle, i.e., collarbone. Such a scar may indicate the presence of an IMD implanted withinpatient16. Visual and audible prompts may originate fromexternal defibrillator12 or from adetection device28, as will be described, in order to facilitate optimal positioning of the detection device over the patient.
• External defibrillator12 may include a user interface that provides a medium for user input indicating whether the user has found a scar near the patient's clavicle. As one example,display24 may include interactive touchscreen displays in which the user may push a button shown ondisplay24 to indicate responses to user prompts. Other interface media such as buttons, switches, hardkeys and softkeys may be used. Such interface media may additionally or alternatively be located ondetection device28. In the case that the user indicates he or she has found a scar near the patient's clavicle,external defibrillator12 may provide follow-up prompts instructing the user to placedetection device28 on the patient's chest near the scar, so thatdetection device28 may establish communication withIMD14, as described in further detail below.
• In some embodiments,external defibrillator12 is capable of communicating withIMD14 by wireless telemetry.External defibrillator12 communicates withIMD14 via telemetry circuitry similar to that used by dedicated programming devices to communicate with the IMD. Dedicated programming devices may communicate withIMD14 via its telemetry circuitry to program or reprogram the operating parameters of the IMD, or to retrieve information stored or collected by the IMD, as is known in the art. Like dedicated programming devices,external defibrillator12 may include corresponding telemetry circuitry to facilitate communication withIMD14 via its telemetry circuitry. The telemetry circuitry ofexternal defibrillator12 andIMD14 may include suitable transceivers, magnets and antennas for communication via radio-frequency (RF) telemetry.
• In the example illustrated byFIG. 1,external defibrillator12 is coupled todetection device28 bycable30.Cable30 may include conductors to carry both power and data to and fromdetection device28. Alternatively, in some embodiments,detection device28 may be battery-powered and communicate withexternal defibrillator12 by wireless telemetry.Detection device28 is placed proximate to, e.g., over,IMD14 by a user ofdefibrillator12 to enable theexternal defibrillator12 to detect and optionally communicate with the IMD. In addition to detecting the presence ofIMD14 inpatient16, thedetection device28 may identify or indicate a location ofIMD14 within the patient. In some embodiments,detection device28 also includes a telemetry device having an antenna and magnet, enablingdefibrillator12 to communicate with the IMD.Defibrillator12 may be removably or permanently coupled todetection device28 bycable30. In some embodiments,detection device28 may be integral with a housing ofexternal defibrillator12, or incorporated into one of electrodes18 and coupled to the external defibrillator by a lead20. In other embodiments,detection device28 may not be coupled todefibrillator12 viacable30, but may instead communicate withdefibrillator12 via wireless communication, such as RF or infrared communication.
• Detection device28 may include a magnet to open or close a switch withinIMD14 and thereby initiate telemetry by the IMD. In particular, by swipingdetection device28 across the patient's body near a suspected implant site, the detection device triggers wireless telemetry byIMD14. Telemetry circuitry withindetection device28 then may communicate withIMD14 and/or measure signal strength of telemetry signals transmitted byIMD14 to guide the user to place the detection device over the implant site of the IMD. Visual and auditory prompts to guide placement ofdetection device28 to a position in proximity to the implant site may originate from thedetection device28 orexternal defibrillator12.
• For example,detection device28 may include a visual indicator such as a series of lights. Asdetection device28 approaches the implant site ofIMD14, a greater number of lights are activated, thereby guiding placement of the detection device toward the implant site. Alternatively, or additionally, an audible indicator may be provided bydetection device28 ordefibrillator12. For example, the audible indicator may be a speaker that emits an audible beep or pitch that increases in volume or frequency as thedetection device28 approaches the implant site, or speech output much like the prompts described above. The speaker may be provided indetection device28 ordefibrillator12. In each case, the output of the visual or audible indicator is a function of the measured signal strength of the telemetry signals emitted byIMD14.
• In another embodiment,detection device28 detects the presence ofIMD14 by inducingIMD14 to initiate a specific pacing protocol when the magnet is positioned nearIMD14. The frequency and duration of the pacing may be measured byexternal defibrillator12 via electrodes18. Magnet rate profiles are different for different pacemaker and defibrillator manufacturers. The change in pacing rate from before and afterdetection device28 was applied would be interpreted byexternal defibrillator12 as an IMD. This information may allowexternal defibrillator12 to confirm when pacing was occurring and determine whether the patient was in ventricular fibrillation and in need of therapy
• In some embodiments, the telemetry circuitry and antennae ofexternal defibrillator12 andIMD14 may be configured to support a signal strength, other signal characteristics, and communication protocol that allow RF telemetry communication between the external defibrillator and the IMD at relatively greater distances. In such embodiments, one or more antennae ofexternal defibrillator12 may be housed within the defibrillator. In this case,external defibrillator12 need not be coupled todetection device28 to communicate with the IMD, anddefibrillator12 may detect and communicate with IMD when brought into general proximity with the IMD.
• FIG. 2 is a conceptual diagram illustratingexternal defibrillator12 in the course of providing another user prompt40 to aid a user in locating anIMD14 implanted within apatient16. Again, user prompt40 may be a voice prompt provided viaspeaker32, a visual prompt provided bydisplay24, or a combination of both. In the example ofFIG. 2, prompt40 advises the user to visually inspect the patient's chest for other signs that an IMD has been implanted inpatient16. In particular, user prompt34 prompts a user to look for a raised portion of the skin near patient's collarbone. Such a raised portion of the skin may indicate the presence of an IMD implanted withinpatient16.
• Prompt40 may be provided if the user is unable to identify a scar perprompt34 ofFIG. 1. Alternatively, prompt40 may be provided even if the user identifies a scar in order to aid the user in more precisely identifying the position ofIMD14, which may not be located immediately under the scar. In the case that the user indicates he has found a scar near the patient's clavicle, or found a raised portion of the skin near the patient's collarbone,external defibrillator12 may provide follow-up voice prompts instructing the user to placedetection device28 on the patient's chest near the scar, so thatdetection device28 may verify the presence ofIMD14 and/or establish communication withIMD14 via telemetry circuitry contained indetection device28.
• External defibrillator12 may provide other voice prompts to guide the user in determining whether an IMD is implanted withinpatient16. For example,external defibrillator12 may prompt the user to make a tactile search for an IMD by palpitating the patient's chest at an area near the patient's clavicles to feel for an IMD. In other words, the user manipulates the tissue near the clavicles for tactile detection of the IMD, which should feel like a hard object embedded within the tissue. As one example, tactile detection may be done when the patient's size or weight is such that an IMD is not readily visually detectable.
• FIG. 3 is a conceptual diagram illustratingexternal defibrillator12 in the course of providing another user prompt44 for locating an implantablemedical device14 implanted within apatient16. As one example, where a user has been prompted according toFIGS. 1 and 2, but has been unable to visually locate evidence of an IMD inpatient16,external defibrillator12 may prompt the user via user prompt44 to place thedetection device28 near an area of the patient's body, e.g., the patient's chest near the patient's clavicle, or the patient's abdomen where the patient is a child.
• Detection device28 may use a magnetic, metal-detecting feature to detect an IMD implanted withinpatient16 in a manner similar to a conventional magnetic stud finder. Alternatively,detection device28 may use another detection method such as an acoustically-based detection method. Consequently, when the user placesdetection device28 on the patient's chest near a clavicle,detection device28 may detect the presence of an IMD implanted withinpatient16.
• Detection device28 may contain an output medium that indicates to the user that the detection device has located an IMD, such as LED lights, beeping, text alerts, or other indication means. As another example, display24 ofexternal defibrillator12 may display a message indicating thatdetection device28 has located an IMD.External defibrillator12 may display a pictorial indication of a location ofIMD14 withinpatient16. Further,detection device28 may include telemetry circuitry for communicating withIMD14. In this embodiment,external defibrillator12 may display a message to indicate thatexternal defibrillator12 has established communication withIMD14.
• FIG. 4 is a conceptual diagram illustrating anexample system10 that includes anexternal defibrillator12 providing auser prompt48 for placing electrodes18 of theexternal defibrillator12 on apatient16. As illustrated inFIG. 4,detection device28 has been placed on the chest ofpatient16, and is in communication withIMD14. It may be undesirable for external defibrillator electrodes to be placed directly overIMD14, because energy from electrodes18 may electrically damageIMD14. Consequently,external defibrillator12 prompts a user via user prompt48 to place the electrodes on the patient's chest, away from the location of theIMD14. By placing electrodes18 at locations some distance from the implant location ofIMD14, interference betweenexternal defibrillator12 andIMD14 may be reduced. Interference betweenexternal defibrillator12 andIMD14 may include electromagnetic interference, which may degrade the signals generated by sensors ofIMD14 and sensors ofexternal defibrillator12.
• FIG. 5 is a block diagram further illustrating exemplary components ofexternal defibrillator12. InFIG. 5,external defibrillator12 is shown coupled topatient16 by electrodes18 and corresponding cables20, as described above. In a typical application,therapy interface60 ofexternal defibrillator12 includes a receptacle, and cables20 plug into the receptacle.
• Therapy interface60 includes a switch (not shown inFIG. 5) that, when activated, couples anenergy storage circuit62 to electrodes18.Energy storage circuit62 stores energy to be delivered topatient16 in the form of a defibrillation shock. The switch may be of conventional design and may be formed, for example, of electrically operated relays. Alternatively, the switch may comprise an arrangement of solid-state devices such as silicon-controlled rectifiers or insulated gate bipolar transistors.
• Energy storage circuit62 includes components, such as one or more capacitors, that store the energy to be delivered topatient16 via electrodes18. Before a defibrillation shock may be delivered topatient16,energy storage circuit62 must be charged. Aprocessor64 directs a chargingcircuit66 to chargeenergy storage circuit62 to a high voltage level. Chargingcircuit66 comprises, for example, a flyback charger that transfers energy from apower source68 toenergy storage circuit62.
• As indicated above,external defibrillator12 may be a manual defibrillator or an AED. Whereexternal defibrillator12 is a manual defibrillator, a user ofdefibrillator12 may select an energy level for each defibrillation shock delivered topatient16.Processor64 may receive the selection made by the user via auser interface70, which may include input devices, such as a keypad and various buttons or dials, and output devices, such as various indicator lights, display24 (FIG. 1), and a speaker.Display24 may include a cathode ray tube (CRT), light emitting diode (LED) array, plasma screen, or liquid crystal display (LCD) screen.
• Whereexternal defibrillator12 is an AED,processor64 selects an energy level. For example,processor64 may select an energy level from a preprogrammed progression of energy levels stored in amemory72 based on the number of defibrillation shocks already delivered topatient16. In some manual defibrillator embodiments,processor64 may select an energy level, e.g., based on a preprogrammed progression, to recommend to a user viauser interface70.
• In either case, when the energy stored inenergy storage circuit62 reaches the desired energy level,processor64controls user interface70 to provide an indication to the user thatexternal defibrillator12 is ready to deliver a defibrillation shock topatient16. For example, the indication may be an indicator light or other visual or audible prompt. The defibrillation shock may be delivered manually or automatically. Where the defibrillation shock is delivered manually, the user may directprocessor64 to deliver the defibrillation shock viauser interface70 by, for example, pressing a button. In either case,processor64 activates the switches ofinterface60 to electrically connectenergy storage circuit62 to electrodes18, and thereby deliver the defibrillation shock topatient16.Therapy interface60,energy storage circuitry62 and chargingcircuit66 are examples of therapy delivery circuitry that deliver therapy topatient16 under control ofprocessor64.
• Processor64 or other circuitry modulates the defibrillation shock waveform delivered topatient16.Processor64 may, for example, control the switches ofinterface60 to regulate the shape and width of the shock.Processor64 may control the switches to modulate the shock to, for example, provide a multiphasic shock, such as a biphasic truncated exponential shock, as is known in the art.
• Processor64 may perform other functions as well, such as monitoring electrical activity of the heart ofpatient16 sensed via electrodes18.Therapy interface60 may include circuitry for sensing the electrical activity of the heart via electrodes18.Processor64 determines whetherheart22 ofpatient16 is fibrillating based upon the sensed electrical activity in order to determine whether a defibrillation shock should be delivered topatient16. Where a defibrillation shock has already been delivered,processor64 evaluates the efficacy of the delivered defibrillation shock by determining ifheart22 is still fibrillating in order to determine whether an additional defibrillation shock is warranted.Processor64 may automatically deliver defibrillation shocks based on these determinations, or may advise the caregiver of these determinations viauser interface70.Processor64 may display an electrocardiogram (ECG) that reflects the sensed electrical activity viauser interface70, e.g., via display24 (FIG. 1).
• Processor64 may store an indication of the time of delivery of each defibrillation shock delivered topatient16 as medical event information withinmemory72 forpatient16.Processor64 may also store the energy level of each pulse and other characteristics of each pulse, such as the width, amplitude, or shape, as medical event information forpatient16.Processor64 may also store a digital representation of the ECG, or a heart rate over time determined based on the electrical activity of the heart ofpatient16 detected via electrodes18 withinmemory72 as medical event information forpatient16. Further,processor64 may control delivery of other types of therapy topatient16 via electrodes18, such as cardioversion or pacing therapy, and store information describing the times that such therapies were delivered and parameters of such therapies, such as cardioversion pulse energy levels and pacing rates, as medical event information forpatient16.
• Whereexternal defibrillator12 is more fully featured, e.g., a manual paramedic or hospital defibrillator,defibrillator12 may also includeadditional sensors74A-74N (collectively “sensors74”) coupled toprocessor64, such as sensors to measure blood oxygen saturation, blood pressure, respiration, and the amount of oxygen or carbon dioxide in the air inhaled or exhaled bypatient16. Sensors74 may be included within or coupled toexternal defibrillator12.External defibrillator12 may include circuitry that conditions the signals generated by sensors74 such that they may be analyzed byprocessor64, such as one or more analog to digital converters to, and suitable filter and amplifier circuitry.
• Processor64 may also store the signals generated by these sensors withinmemory72 as medical event information forpatient16. As examples,processor64 may store any of a capnograph, a plethysmograph, a blood oxygen saturation over time, a blood pressure over time, a pulse rate over time determined based on measured blood pressure, end tidal carbon dioxide measurements, and/or measurements of the fraction of carbon dioxide in air inspired or expired withinmemory72 as medical event information forpatient16.Processor64 may also receive other information collected by a user during treatment ofpatient16, such as a location of treatment or time of death, and store such information as medical event information for the patient.Processor64 may begin to store medical event information inmemory72 whendefibrillator12 is powered on to respond to a medicalemergency involving patient16.
• Processor64 may, for example, include one or more of a microprocessor, DSP, ASIC, FPGA, or other equivalent integrated or discrete logic circuitry.Memory72 may include program instructions that causeprocessor64 to perform the functions attributed toprocessor64 anddefibrillator12 herein. Accordingly, this disclosure also contemplates computer-readable media storing instructions to causeprocessor64 to provide the functionality described herein.Memory72 may include any of a variety of solid state, magnetic or optical media, such as RAM, ROM, CD-ROM, magnetic disk, EEPROM, or flash memory.
• In the example illustrated byFIG. 5,external defibrillator12 includes a detection/telemetry interface76. Detection/telemetry interface76 may include a port or other physical interface to receivecable30, which is coupled todetection device28, and to electrically couple circuitry withindefibrillator12 to circuitry withindetection device28 viacable30.Cable30 may include conductors to carry both power and data to and fromdetection device28. Alternatively,detection device28 may be battery-powered and communicate withexternal defibrillator12 by wireless telemetry.Processor64 communicates withIMD14 via detection/telemetry interface76 anddetection device28.
• In some embodiments, as illustrated inFIG. 5, detection/telemetry interface76 may convey data betweenprocessor64 anddetection device28, as well as provide power fromdefibrillator12 to power the circuitry withindetection device28. As will be described below with reference toFIG. 7,detection device28 may incorporate wireless telemetry circuitry and one or more antennae for communication withIMD14.Detection device28 may also incorporate a magnet to trigger initiation of telemetry byIMD14. In such embodiments, detection/telemetry interface76 may include any of a variety of known digital data interfaces, such as a universal serial bus (USB) interface. In some embodiments, the detection device may not be integrated with telemetry circuitry. In such embodiments,detection device28 may be configured simply to trigger initiation of telemetry byIMD14. Telemetry circuitry may be incorporated withindefibrillator12, or there may be a separate telemetry interface and telemetry head, independent ofdetection device28, for providing communication withIMD14.
• In other embodiments,external defibrillator12 may include the telemetry circuitry, anddetection device28 may include only one or more antennae for communication withIMD14. In this case,detection device28 receives wireless telemetry signals fromIMD14 but transmits the received signals to defibrillator for processing. Further, in still other embodiments,defibrillator12 may include both telemetry circuitry and antennae for communication withIMD14.Defibrillator12 need not be coupled todetection device28 in order to communicate withIMD14. In such embodiments,detection device28 may provide wireless communication withdefibrillator12, and may be battery powered, e.g., with a non-rechargeable or rechargeable battery, instead of receiving power fromdefibrillator12.
• FIG. 6 is a flowchart illustrating exemplary operation ofexternal defibrillator12.External defibrillator12 is brought topatient16 in response to a medicalemergency involving patient16, such as a ventricular fibrillation (VF) or sudden cardiac arrest (SCA) experienced by the patient. A user operatesexternal defibrillator12, and follows prompts fromexternal defibrillator12 to visually inspect patient16 to determine whetherpatient16 has an IMD, and if so, to determine the location of the IMD withinpatient16. In some embodiments, the user is aided not only by visual or audible prompts, but alsodetection device28.
• In the example ofFIG. 6,external defibrillator12 prompts the user to examine the patient's chest for a scar near the patient's clavicle (80). As mentioned previously,external defibrillator12 may include a user interface that provides a medium for user input indicating whether the user has found a scar near the patient's clavicle. If the user indicates he has found such a scar (yes branch of82),external defibrillator12 prompts the user to placedetection device28 on the patient near the scar (84), so thatdetection device28 may initiate communication byIMD14, e.g., by triggering telemetry with a magnet carried bydetection device28.
• If the user indicates he does not find such a scar (no branch of82),external defibrillator12 prompts the user to examine the patient for a raised portion of skin near the patient's clavicle (86). If the user indicates he has found such a raised portion of skin (yes branch of88),external defibrillator12 prompts the user to placedetection device28 on the patient near the raised portion (90), so thatdetection device28 may initiate communication byIMD14. Again,detection device28 may integrate wireless telemetry circuitry for communication withIMD14, or simply include a magnet to trigger telemetry byIMD14.
• If the user indicates he does not find such a raised portion of skin (no branch of88),external defibrillator12 prompts the user to placedetection device28 on the patient near the patient's clavicle (92).External defibrillator12 may provide other prompts (not shown) prompting the user to move the detection device to various areas of the patient's chest to use the detection capabilities of the detection device to search for an IMD. For example, the user may swipedetection device28 across the patient's chest, near the clavicle or elsewhere, to initiate telemetry byIMD14.Detection device28 may include telemetry circuitry to detect telemetry signals, and thereby detect the presence ofIMD14. Based on detected signal strength,detection device28 may indicate the relative proximity of thedetection device28 to the implant site ofIMD14. As discussed previously,detection device28 may include a visible or audible indicator, or both, to indicate the strength of the telemetry signal, and hence the distance from theIMD14. An indicator, such as an array of lights in which more lights are lit as signal strength becomes stronger, can help the userguide detection device28 toward the implant site ofIMD14. In turn, upon placement ofdetection device28 in close proximity toIMD14, the increased strength of the telemetry signal will promote more reliable telemetry with the IMD.
• In embodiments in whichdetection device28 includes telemetry circuitry for communicating withIMD14,detection device28 placed on the patient's chest may attempt to establish communication with IMD14 (94). If communication cannot be established,external defibrillator12 may continue with its typical therapy instructions without communicating with an IMD (98). As one example,detection device28 may be unable to establish communication becausepatient16 does not have an IMD at all. As another example,detection device28 may be unable to locate an IMD implanted withinpatient16. If communication is established withIMD14, thenexternal defibrillator12 may coordinate therapy with IMD14 (98), as described in further detail below.
• FIG. 7 is a block diagram further illustrating anexemplary detection device28 ofFIG. 1. In the illustrated example,detection device28 includes anantenna100 coupled totelemetry circuitry102.Telemetry circuitry102 includes a wireless transceiver for RF communication withIMD14 viaantenna100.Telemetry circuitry102 may also include various circuitry for conditioning signals transmitted or received viaantenna100, such as analog to digital and digital to analog converters, and appropriate amplifiers or filters.
• Adefibrillator interface104 ofdetection device28 interfaces with detection/telemetry interface76 (FIG. 5) ofexternal defibrillator12.Interface104 may include a plug or other physical interface oncable30 that may be used to removably or permanently coupledetection device28 todefibrillator12, and which electrically couples the circuitry withindetection device28 to circuitry withindefibrillator12 via detection/telemetry interface76. As illustrated inFIG. 7,interface104 may convey data betweentelemetry circuitry102 andexternal defibrillator12, and may receive power fromdefibrillator12 for distribution to the various components ofdetection device28.Interface104 may include any of a variety of known digital data interfaces, such as a universal serial bus (USB) connector. In some embodiments, the USB interface also may carry operating power for components ofdetection device28. In other embodiments,interface104 may communicate withdefibrillator12 via a wireless interface, such as an RF or infrared interface. In these embodiments,defibrillator12 need not be coupled todetection device28 in order to communicate withIMD14. In such embodiments,detection device28 may be battery powered instead of receiving power fromdefibrillator12.
• Detection device28 also includes amagnet108 to trigger initiation of telemetry byIMD14 whendetection device28 is swiped across the patient's body in proximity to the IMD implant site.Processor110 processes signals received fromtelemetry circuitry102, e.g., for transmission todefibrillator12 viadefibrillator interface104. In addition,processor110 may measure the signal strength of telemetry signals received viatelemetry circuit102 in order to drive anindicator112, such as a visual or audible indicator. As described above, indicator serves to indicate the relative proximity ofdetection device28 toIMD14 based on the measured signal strength of telemetry signals received from the IMD. The signal strength measurement may be performed for digital signals converted bytelemetry circuitry102. Alternatively, an analog signals strength measurement may be obtained by an analog measurement circuit based on analog signals received by telemetry circuitry. In either case, the signal strength measurement is used to driveindicator112.
• FIG. 8 is a block diagram illustrating anexample detection device28. In the example ofFIG. 8,detection device28 includes ahousing111, anadhesive layer112 and aremovable backing strip114.Detection device28 is coupled toexternal defibrillator12 bycable30.Adhesive layer112 may comprise a layer of non-toxic adhesive for adheringdetection device28 to the skin ofpatient16. A user may removeremovable backing layer114 to exposeadhesive layer112, and then attachdetection device28 topatient16. In operation, abottom surface115 ofdetection device28 has a substantially planar surface designed to engage and slide across the skin ofpatient16.
• In one embodiment, once a location ofIMD14 withinpatient16 has been determined,defibrillator12 may prompt the user to attachdetection device28 to the patient's skin overIMD14. In particular, the user removesbacking layer114 to exposeadhesive layer112, and thereby permit adhesive fixation ofdetection device28 to the skin ofpatient16 at the location of the IMD. In this manner, whendetection device28 includes telemetry circuitry,detection device28 remains in proximity toIMD14 to maintain communication between the two devices, even whenpatient16 is moved or transported.Adhesive layer114 thereby promotes reliable and robust communication betweendefibrillator12 andIMD14. In one embodiment,detection device28 may be a disposable unit that may be decoupled fromcable30 ordefibrillator12 and discarded after use.
• FIG. 9 is a conceptual diagram illustrating anexample system10 that includes anexternal defibrillator12 communicating with anIMD14 implanted within apatient16, e.g., viadetection device28 or independently ofdetection device28.IMD14 may store a variety ofinformation regarding patient16 andIMD14 itself within a memory unit of IMD14 (not shown), andexternal defibrillator12 may retrieve this information fromIMD14 during a telemetry session. For example,IMD14 may store demographic information forpatient16, such as name, height, weight, sex, age, residence, date of birth, and the like. Further,IMD14 may store treatment alerts forpatient16, such as medications taken by the patient, allergies of the patient, physician name, physician phone number, patient's hospital, patient history, patient medical condition, patient blood type, or a do not resuscitate (DNR) order for the patient.
• IMD14 may store information describing the type ofIMD14, pacemaker or internal defibrillator lead types, ejection fraction, implant lead data, an implant date, lead configuration, lead impedance and current programmed parameters, such as a current pacing mode, pacing amplitude, or defibrillation amplitude.IMD14 may also store information identifying the implant location ofIMD14. Whenprocessor64 ofexternal defibrillator12 receives such information fromIMD14,processor64 may store the information inmemory72 as medical event information forpatient16. Such information may then be included in a report of the treatment ofpatient16, e.g., a “run” report, along with other medical event information collected byexternal defibrillator12 as discussed above with reference toFIG. 5. Alternatively, such information may be received directly by a run reporting system fromIMD14. Paramedics, first responders, or other users ofexternal defibrillator12 may be required to prepare such run reports by an emergency medical service or other regulating authority. Alternatively, or additionally, such information may be downloaded from the detection device or the run reporting system to a database management system of an emergency room or other location. The information would then be available to a physician.
• Becauseexternal defibrillator12 may retrieve such patient and device information fromIMD14 and include the information within the medical event information forpatient16 automatically, a user of the external defibrillator may not be required to take time to collect such information frompatient16, family members, or bystanders, and enter the information intoexternal defibrillator12 manually viauser interface70 of the defibrillator. Consequently, the user's time and attention may remain focused on treatingpatient16. In some embodiments, ifexternal defibrillator12 is an AED, it may be configured to transfer such information to another defibrillator, such as an ALS defibrillator carried by a paramedic, e.g., by wired or wireless communication, or by physical transfer of a memory card or other data storage medium.
• IMD14 may also store physiological and therapy information. For example,IMD14 may store information relating to current status and history of therapy delivery by the IMD topatient16.External defibrillator12 may retrieve this stored information fromIMD14, and may also receive real-time values for one or more physiological parameters and real-time indications of therapies delivered or scheduled for delivery by the IMD from the IMD. For example,external defibrillator12 may receive EGM samples sensed byIMD14 via leads26, and may receive a real-time ECG recorded and stored byIMD14. EGM signals are a record of changes of cardiac electric potentials, as measured with electrodes placed within the heart, either through catheters or transvenous leads. Real-time ECG samples may be collected using electrodes built into the IMD exterior metal housing.External defibrillator12 may store any or all of the past or real-time information received fromIMD14 withinmemory72.
• In addition,external defibrillator12 may receive information indicating events or operations within an implanted device, such as pacing, shock or sensing events, all of which may be referred to as IMD event information. An example of such information is the information presented by the Marker Channel™ functionality provided by various IMDs manufactured by Medtronic, Inc. of Minneapolis, Minn. Such IMD event information can be used by theexternal defibrillator12 to interpret operation ofIMD14. For instance, if the patient is in ventricular fibrillation, a life threatening event, and the patient has a pacemaker that is delivering pacing pulses,external defibrillator12 may use the IMD event information obtained fromIMD14 to determine if the pulses it records from the electrodes18 are occurring at the same time as the paced events indicated by the IMD event information. If so, thenexternal defibrillator12 can conclude that theIMD14 is generating these events. As another example,external defibrillator12 may use electrodes18 to measure the rate of change of a measured voltage to recognize pacing pulses. In either case, theexternal defibrillator12 can then analyze periods between the pacing pulses to identify ventricular fibrillation or send a command to the pacemaker to change the pacing rate to facilitate better interpretation of the patient's intrinsic rhythm. As a further example,external defibrillator12 may detect an impedance signal generated byIMD14, e.g., changes in tissue impedance due to pacing pulses byIMD14.External defibrillator12 may use this information to determine thatIMD14 is present withinpatient16.
• Further,external defibrillator12 may receive EGM or heart rate data stored byIMD14, or ECG information obtained via electrodes18, including average values or other statistical summaries of the heart rate ofpatient16 over time.External defibrillator12 may also receive current heart rate values, or current average heart rate value, e.g., averaged over a relatively short period of time such as a minute, from the IMD.External defibrillator12 may also receive stored or real-time values for other physiological parameters that may be detected byIMD14 as discussed above, such as blood pressure and blood flow. Using this information,external defibrillator12 can make more informed shock decisions, and control the timing and parameters of shocks delivered to the patient by the external defibrillator.
• Processor64 ofexternal defibrillator12 may provide prompts to a user viauser interface70, e.g., viaspeaker32 and/ordisplay24, based on the information received fromIMD14. In some embodiments, providing prompts based on the information received fromIMD14 comprises modifying programmed prompts that may have otherwise been provided to a user ofdefibrillator12 in the absence of communication withIMD14. For example,memory72 ofexternal defibrillator12 may store visual or audible prompts provided to a user byprocessor64 that indicate locations for the user to place electrodes18 onpatient16. If anIMD14 is detected, however, the prompts may be modified to direct the user to place electrodes18 at locations situated at a distance from the IMD implant site. For example, the prompts may advise the user to place the defibrillation electrodes18 at least six inches (15.24 cm) away from the IMD implant site. In this manner, electromagnetic interference betweenexternal defibrillator12 andIMD14, as well as risk of damage to or reprogramming ofIMD14 caused by defibrillation shock energy levels, may be reduced. Positioning the electrodes18 further away from theIMD14 may be beneficial to improve the performance of the IMD andexternal defibrillator12 when both are present and operating together.
• As another example,processor64 may prompt a user ofexternal defibrillator12 with patient treatment alert information received fromIMD14. For example,processor64 may provide prompts to the user indicating allergies, potential drug interactions, patient history, patient medical condition, or a DNR order forpatient16. Because patient treatment alert information may impact treatment decisions made by a user ofexternal defibrillator12,processor64 may use bold or flashing text, flashing lights, audible alerts, or the like to draw the attention of the user to the presence of one or more patient treatment alerts.
• Additionally,processor64 may prompt a user with a time of onset of the current medical emergency, or a time elapsed since onset of the medical emergency, based on the time of onset information received fromIMD14. The efficacy of therapies that could be delivered to the patient may vary based on the amount of time elapsed since onset of the medical emergency, e.g., amount of time in fibrillation or SCA. Consequently, a user ofexternal defibrillator12 may provide different therapies topatient16 based on the time of onset or amount of time elapsed indicated byexternal defibrillator12 based on information received fromIMD14. For example, a user ofexternal defibrillator12 may elect to deliver defibrillation shocks topatient16 if the patient has been in SCA or fibrillation for less than five minutes, and elect to perform CPR on the patient if the patient has been in SCA or fibrillation for greater than five minutes. In some embodiments,external defibrillator12 may prompt the user to provide a particular therapy or type of monitoring based on the onset or elapsed time information received from IMD.
• Further, if the received information indicates thatIMD14 is scheduled to deliver a therapy topatient16,processor64 may provide a prompt notifying the user of the upcoming delivery of therapy. For example,IMD14 may identify a shockable arrhythmia ofheart22, and transmit an indication toexternal defibrillator12 thatIMD14 will deliver a defibrillation shock to the heart.Processor64 may direct the user to avoid contact with patient, e.g., stop CPR, for a period of time to avoid receiving a portion of the energy of the defibrillation shock delivered byIMD14, which may cause discomfort or injury to the user.
• Processor64 may also display some or all of the information received fromIMD14 viadisplay24. For example,processor64 may receive and display the name ofpatient16 as stored byIMD14, allowing a user ofexternal defibrillator12 to address the patient by name without having to ask the patient, family members, or other bystanders.
• Further,processor64 may display real-time values of physiological parameters sensed byIMD14, such as a real-time ECG or EGM sensed byIMD14 via leads26, via display. Through communication withIMD14,external defibrillator12 may be able to display values of physiological parameters that may not have otherwise been able to be sensed byexternal defibrillator12.Processor64 may provide prompts based on some of these values. For example,processor64 may provide audio or visual prompts regarding the efficacy of CPR provided by a user ofexternal defibrillator12, e.g., instruction to apply more or less forceful chest compressions, based on blood pressure or blood flow values measured byIMD14.
• EGM waveforms detected byIMD14 via leads26 or ECG waveforms may be of a higher quality than an ECG detected byexternal defibrillator12 via electrodes18. For example, an EGM or ECG waveform detected byIMD14 may be less likely to include motion artifacts caused by CPR chest compressions than an ECG detected by the external defibrillator. Consequently, where available fromIMD14,processor64 of the external defibrillator may display a real-time EGM or ECG waveforms received fromIMD14. In some embodiments, the processor may select either the ECG detected by the external defibrillator or ECG or EGM received from the IMD based on criteria related to the quality of the ECGs, such as noise or impedance. For example, the processor may select the IMD ECG or EGM when available unless signal to noise ratio of the external ECG, i.e., the ECG detected by the external defibrillator, is above a threshold value.
• Processor64 may also display information indicating therapies delivered topatient16 byIMD14 viadisplay22.Processor64 may also display information indicating a current status ofIMD14, i.e., whatIMD14 is currently doing. If the displayed information indicates that the IMD has already delivered therapy topatient16 in response to the current medical emergency, the user may consider such information and thereby avoid delivering redundant therapies topatient16. For example, the displayed information may indicate energy levels of defibrillation shocks delivered to patient byIMD14, and the user may select an energy level for a defibrillation shock to be delivered byexternal defibrillator12 that is adjusted based on the energy levels of the defibrillation shocks delivered by the IMD. For example, the user may select an energy level for a defibrillation shock to be delivered byexternal defibrillator12 that is greater than the energy levels of the defibrillation shocks delivered by the IMD if the pulse delivered by the IMD failed to defibrillateheart22.
• External defibrillator12 may also deliver therapy topatient16 based on the information received fromIMD14. For example, in embodiments in whichprocessor64 selects an energy level for a defibrillation shock to be delivered topatient16 byexternal defibrillator12,processor64 may select the energy level based on the information. The information received fromIMD14 may indicate an energy level of a defibrillation shock delivered topatient16 byIMD14, andprocessor64 may select an energy level for a defibrillation shock to be delivered byexternal defibrillator12 based on the indicated energy level.Processor64 may select a higher energy level to avoid delivering a redundant defibrillation shock which may have already proven ineffective at ending fibrillation ofheart22.
• As another example, in embodiments in whichprocessor64 analyzes an ECG to determine whether to deliver therapy, e.g., a defibrillation shock, topatient16,processor64 may analyze a real-time ECG received fromIMD14. As discussed above, the ECG or EGM received fromIMD14 may be of a higher quality, e.g., less susceptible to motion artifacts from CPR chest compressions, than an ECG detected via electrodes18. Consequently, by using an ECG or EGM received fromIMD14,processor64 may be able to more accurately determine whether therapy should be delivered topatient16. Additionally, as discussed above,processor64 may select one of the IMD and external ECG for analysis based on a criterion related to the quality of at least one of the ECGs, thereby supporting coordinated operation ofexternal defibrillator12 andIMD14.
• Further, in some embodiments,IMD14 may use different algorithms to determine whether to deliver therapy topatient16 than are available toprocessor64, andprocessor64 may deliver therapy based on a therapy delivery decision received fromIMD14. For example,IMD14 may apply arrhythmia detection algorithms to the rhythm ofheart22 that distinguish between ventricular and supra-ventricular arrhythmias.IMD14 may decide that a defibrillation shock should be delivered in response to detection of a ventricular arrhythmia, and that a defibrillation shock should not be delivered in response to detection of a supra-ventricular arrhythmia.Processor64 may control delivery of a defibrillation shock topatient16 based on a defibrillation shock delivery decision received fromIMD14. In this manner,external defibrillator12 may, for example, avoid delivering a defibrillation shock to treat a supra-ventricular arrhythmia. In some embodiments, a user may override a decision byprocessor64 not to deliver therapy based on information received fromIMD14, anddirect defibrillator12 to deliver therapy.
• Additionally,processor64 may control delivery of therapy byexternal defibrillator12, e.g.,control charging circuit66 andtherapy delivery interface60, based on onset or elapsed time information received fromIMD14. For example,processor64 may select a therapy, such as defibrillation, cardioversion or pacing, or the energy levels for such therapy, based on the time.Processor64 may alternatively suspend delivery of therapy byexternal defibrillator12 based on the time information.
• Processor64 ofexternal defibrillator12 may also control delivery of therapy byIMD14. For example,processor64 may suspend delivery of therapy byIMD14 during treatment ofpatient16 withexternal defibrillator12. By suspending delivery of therapy byIMD14,external defibrillator12 may avoid interference between therapies delivered byIMD14 anddefibrillator12. As another example,external defibrillator12 may deliver therapy upon receiving information fromIMD14 thatIMD14 has a low battery, or thatIMD14 has delivered a maximum number of shocks.
• As another example,processor64 may change a therapy delivery mode ofIMD14. For example, after defibrillation byexternal defibrillator12, some patients may benefit from pacing in a different mode than the mode in whichIMD14 had been programmed.Processor64 may change the mode ofIMD14 by, for example, changingIMD14 from single to dual chamber pacing or from demand to non-demand pacing, or by changing a pacing rate or the aggressiveness of rate responsive pacing or by increasing pacing amplitudes.
• Further, the hearts of some patients are left in a state of pulseless electrical activity after being defibrillated. Such patients may benefit from delivery of post extra-systolic potentiation (PESP) pacing, which may increase the cardiac output of their heart. IfIMD14 is capable of delivering post extra-systolic pacing pulses,processor64 may directIMD14 to do so afterheart22 has been defibrillated. In some embodiments,processor64 may directIMD14 to delivery other therapies provided by the IMD that may not be available from the external defibrillator, such as cardioversion or anti-tachycardia pacing therapies or by increasing pacing amplitudes, after the shock was delivered by the AED.
• Additionally,processor64 may directIMD14 to deliver therapy that is coordinated with therapy delivered bydefibrillator12. For example,processor64 may directIMD14 to deliver a defibrillation shock synchronized with, or with some other temporal relationship to, a defibrillation shock delivered bydefibrillator12. Delivery of defibrillation shocks by bothIMD14 andexternal defibrillator12 may be more efficacious than delivery of defibrillation shocks by either the external defibrillator or the IMD alone.
• As another example,external defibrillator12 may include pacing circuitry for delivery of pacing pulses toheart22 ofpatient16 via electrodes18. To theextent IMD14 is not capable of delivering post extra-systolic pacing pulses,processor64 may control the pacing circuitry to deliver pacing pulses an extra-systolic interval after delivery of a pacing pulse byIMD14, or an intrinsic depolarization ofheart22.Processor64 ofexternal defibrillator12 may interrogateIMD14 to identify the therapies sensing capabilities provided by the IMD.Processor64 may control the IMD to deliver a therapy alone, or in coordination with the external defibrillator, based on this capability information retrieved from the IMD.
• As described above,processor64 collects medical event information during treatment ofpatient16 withexternal defibrillator12, and stores the medical event information withinmemory72 of the external defibrillator.Processor64 may also store the medical event information intoIMD14. In this manner, caregivers who subsequently treatpatient16 and have access to a programming device that communicates withIMD14 may be able to retrieve the medical event information. In the absence of communication betweenIMD14 andexternal defibrillator12, such caregivers may not have had access or timely access to the medical event information, which may inform treatment decisions made by the caregivers, and may supplement the medical records maintained forpatient16 by the caregivers. In some embodiments, rather than a caregiver retrieving the information with a programming device,IMD14 may transmit the medical event information to a computing device, computing network, or other data repository at, for example, a hospital. The medical event information may supplement the hospitals records for the patient, and may be available to caregivers throughout the hospital who may treat the patient.
• Various embodiments of the invention have been described. However, one skilled in the art will appreciate that various modifications may be made to the described embodiment without departing from the scope of the claimed invention. For example, although wireless communication has been described herein primarily in the context of RF telemetry, the invention is not so limited. An external defibrillator and IMD according to the invention may include any of a variety of RF, optical, acoustic, or other transducers for wireless communication. Further, although described in the context of communication with an IMD, an external defibrillator according to the invention may communicate with other external medical devices that are associated with the patient, such as a wearable defibrillator or Holter monitor. In addition, although described in the context of an external defibrillator, the IMD may be any implantable device, such as a neurostimulator, a drug pump, or a diabetes monitoring device. These and other embodiments are within the scope of the following claims.

Claims (28)

1. An external defibrillator comprising:

a defibrillation therapy generator;

electrodes coupled to the defibrillation therapy generator; and

a user interface that presents one or more prompts to a user of the external defibrillator to detect presence of an implantable medical device (IMD) in a patient.

2. The external defibrillator ofclaim 1, wherein the user interface presents a prompt requesting that the user examine an area of the body of the patient for evidence of presence of an IMD in the patient.

3. The external defibrillator ofclaim 1, wherein the user interface presents:

a first prompt requesting that the user examine a chest of the patient for a scar near clavicles of the patient;

a second prompt requesting that the user examine the chest of the patient for a raised portion of skin near the clavicles of the patient;

a third prompt requesting that the user place a detection device on the chest of the patient near the clavicles of the patient; and

a fourth prompt requesting that the user place the electrodes on the patient's chest based on the location of the IMD.

4. The external defibrillator ofclaim 1, wherein the prompts include at least one of audible prompts or visual prompts, the external defibrillator including a device to present at least one of the audible prompts or visual prompts.

5. The external defibrillator ofclaim 1, wherein the user interface provides a medium for user input indicating that the user has detected presence of the IMD.

6. The external defibrillator ofclaim 1, further comprising a detection device that detects presence of the IMD, wherein the detection device is configured to trigger initiation of telemetry by the IMD and detect the presence of the IMD based on reception of one or more telemetry signals from the IMD.

7. The external defibrillator ofclaim 6, further comprising a processor that receives information from the IMD via the telemetry signals, wherein the processor controls the therapy generator to deliver therapy to the patient based on the received information.

8. The external defibrillator ofclaim 7, wherein the received information includes electrogram information, electrocardiogram information, and IMD event information.

9. A method comprising generating one or more prompts to a user of an external defibrillator to detect presence of an implantable medical device (IMD) in a patient.

10. The method ofclaim 9, further comprising presenting a prompt requesting that the user examine an area of the body of the patient for evidence of presence of the IMD in the patient.

11. The method ofclaim 9, further comprising generating:

a first prompt requesting that the user examine a chest of the patient for a scar near clavicles of the patient;

a second prompt requesting that the user examine the chest of the patient for a raised portion of skin near the clavicles of the patient;

a third prompt requesting that the user place a detection device of the external defibrillator on the chest of the patient near the clavicles of the patient; and

a fourth prompt requesting that the user place electrodes of the external defibrillator on the patient's chest based on the location of the IMD.

12. The method ofclaim 9, wherein generating one or more prompts includes generating at least one of audible prompts or visual prompts.

13. The method ofclaim 9, wherein detecting presence of an IMD in the patient comprises triggering initiation of telemetry by the IMD and detecting the presence of the IMD based on reception of one or more telemetry signals from the IMD.

14. The method ofclaim 13, further comprising:

receiving information from the IMD via the telemetry signals; and

delivering therapy to the patient based on the received information.

15. The method ofclaim 14, wherein the received information includes electrogram information, electrocardiogram information, and IMD event information.

16. An external-defibrillator comprising:

a defibrillation therapy generator;

electrodes coupled to the defibrillation therapy generator; and

a detection device that detects presence of an implantable medical device (IMD) in a patient.

17. The external defibrillator ofclaim 16, further comprising an output medium that indicates presence of the IMD.

18. The external defibrillator ofclaim 17, wherein the output medium provides at least one of a visual indication or an audible indication of presence of the IMD.

19. The external defibrillator ofclaim 16, wherein the detection device is configured to trigger initiation of telemetry by the IMD and detect the presence of the IMD based on reception of one or more telemetry signals from the IMD.

20. The external defibrillator ofclaim 16, wherein the detection device includes a magnet to trigger initiation of telemetry by the IMD.

21. The external defibrillator ofclaim 20, further comprising a processor that receives information from the IMD via the telemetry signals, wherein the processor controls the therapy generator to deliver therapy to the patient based on the received information.

22. The external defibrillator ofclaim 21, wherein the received information includes electrogram information, electrocardiogram information, and IMD event information.

23. The external defibrillator ofclaim 22, wherein the received information comprises patient information and IMD information.

24. A method comprising:

detecting presence of an implantable medical device (IMD) in a patient via a detection device associated with an external defibrillator; and

indicating presence of the IMD to a user of the external defibrillator.

25. The method ofclaim 24, wherein indicating the presence of the IMD comprises indicating the presence of the IMD via at least one of an audible indication or a visual indication.

26. The method ofclaim 24, further comprising:

placing the detection device near the IMD, wherein the detection device includes a magnet to trigger initiation of telemetry by the IMD; and

communicating with the IMD via a telemetry device, wherein the telemetry device is integrated with the detection device.

27. The method ofclaim 26, further comprising:

receiving information from the IMD via the telemetry device; and

delivering therapy to the patient based on the received information.

28. The external defibrillator ofclaim 27, wherein the received information includes electrogram information, electrocardiogram information, and IMD event information.

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