Abstract: An external defibrillator may have a controller to set the defibrillator in a synchronous shock operating mode or an asynchronous shock operating mode, a shock module to cause the defibrillator to deliver shock therapy to a patient according to the present operating mode of the defibrillator, and a heart rhythm detector to detect a heart rhythm of the patient. The defibrillator may also have a mode assessment module to determine whether the present operating mode or selected defibrillation energy of the defibrillator is appropriate based on the detected heart rhythm of the patient.

Abstract: Systems and methods are provided for graphically configuring leads for a medical device. According to one aspect, the system generally comprises a medical device and a processing device, such as a programmer or computer, adapted to be in communication with the medical device. The medical device has at least one lead with at least one electrode in a configuration that can be changed using the processing device. The processing device provides a graphical display of the configuration, including a representative image of a proposed electrical signal to be applied by the medical device between the at least one electrode of the medical device and at least one other electrode before the medical device applies the electrical signal between the at least one electrode and the at least one other electrode. In one embodiment, the graphical display graphically represents the lead(s), the electrode(s), a pulse polarity, and a vector.

Abstract: A wearable therapeutic device to facilitate care of a subject is provided. The wearable therapeutic device can include a garment having a sensing electrode. The garment includes at least one of an inductive element and a capacitive element, and a controller identifies an inductance of the inductive element or a capacitance of the capacitive element, and determines a confidence level of information received from the sensing electrode based on the inductance or the capacitance. The wearable therapeutic device also includes an alarm module coupled with the controller and configured to provide a notification to a subject based on the confidence level.

Abstract: An implantable medical device and associated method control the delivery of extra systolic stimulation by determining a coupling interval, setting an extra systolic interval in response to the coupling interval; and delivering a supraventricular stimulation pulse upon expiration of the extra systolic interval. The supraventricular stimulation pulse evokes a depolarization that is conducted to the ventricles occurring at a ventricular coupling interval relative to a ventricular event.

Abstract: Provided is a ventricular assist device cannula, and more particularly, a ventricular assist device cannula with electrodes. An exemplary embodiment of the present invention provides a ventricular assist device cannula with electrodes, including: a connecting tube connecting an incision of a body tissue and a ventricular assist device so that blood can flow; and electrodes connected with the connecting tube and contacting the incision of the body tissue to transfer an electric signal to the body tissue.

Abstract: An implantable device monitors and treats heart failure, pulmonary edema, and hemodynamic conditions and in some cases applies therapy. In one implementation, the implantable device applies a high-frequency multi-phasic pulse waveform over multiple-vectors through tissue. The waveform has a duration less than the charging time constant of electrode-electrolyte interfaces in vivo to reduce intrusiveness while increasing sensitivity and specificity for trending parameters. The waveform can be multiplexed over multiple vectors and the results cross-correlated or subjected to probabilistic analysis or thresholding schemata to stage heart failure or pulmonary edema. In one implementation, a fractionation morphology of a sensed impedance waveform is used to trend intracardiac pressure to stage heart failure and to regulate cardiac resynchronization therapy. The waveform also provides unintrusive electrode integrity checks and 3-D impedancegrams.

Abstract: Electrical energy is conveyed via an implanted tissue stimulation system into tissue of the patient over a period of time. Electrical parameter data (e.g., impedance data and/or field potential data) is measured based on the electrical energy conveyed into the tissue of the patient, whereby the electrical parameter data is modulated in response to the physical activity of the patient to generate a time-varying signal (e.g., an oscillating signal). The time-varying signal is analyzed, and the physical activity of the patient (e.g., the physical activity level of the patient or the physical events performed by the patient) is tracking during the time period based on the analyzed time-varying signal.

Abstract: Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the patient, and a processor coupled with the baroreflex activation device(s) and the sensor(s) for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, the system is fully implantable within a patient, such as in an intravascular, extravascular or intramural location.

Abstract: A method for accurately determining timing points for T-wave shocks is particularly useful in a system for determining a cardiac shock strength in an implantable cardioverter defibrillator (ICD. The method involves acquiring at least one first signal, acquiring at least a second signal, comparing the signals, and selecting a timing point with the T-wave of the signal. The first and second signals may be two different aspects of a single electrogram, first and second electrograms, or a combination thereof. Comparison preferably involves signal alignment and qualitative analysis.

Abstract: A system and method for determining complex intercardiac impedance to detect various cardiac functions are disclosed involving a signal generator means for providing an adjustable direct current signal, a modulator for modulating the adjustable direct current signal to produce a modulated signal, at least one electrode for propagating the modulated signal across a myocardium, at least one sensor for detecting an outputted modulated signal from the myocardium, and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal. The at least one circuit comprises an amplifier, a demodulator, and an integrator. The amplitude and phase of the final outputted modulated signal indicate the complex impedance of the myocardium. Changes in the complex impedance patterns of the myocardium provide indication of reduced oxygen and blood flow to the myocardium.

Abstract: Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the patient, and a processor coupled with the baroreflex activation device(s) and the sensor(s) for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, the system is fully implantable within a patient, such as in an intravascular, extravascular or intramural location.

Abstract: Devices, systems and methods relating to defibrillation and, more specifically, pulse parameters and electrode configurations for reducing patient discomfort are disclosed. Embodiments provide for an implantable defibrillator having an electrode lead system, at least one sensor for sensing a heart condition and emitting a condition signal, a controller in communication with the at least one sensor and configured to determine from the condition signal whether the heart is fibrillating and emitting a command signal if fibrillation is detected and a voltage generator communicating with the controller and the electrode system to communicate at least one defibrillation pulse to the electrode system, wherein the at least one defibrillation pulse includes at least one pulse having a voltage greater than 80 volts and a time duration up to 1000 microseconds.

Abstract: Methods and apparatus for accurately and painlessly measuring the impedance between defibrillation electrodes implanted in a patient utilize a high current test pulse delivered with a sufficiently high current to produce an accurate measurement of the defibrillation electrode impedance while limiting the duration of the test pulse such that the pain sensing cells in the patient do not perceive the test pulse. In one embodiment, the test pulse is generated from the high voltage transformer without storing energy in the high voltage capacitors and is delivered to the defibrillation electrodes in the patient utilizing the high voltage switching circuitry.

Abstract: A method for measuring impedance of a tissue (20), consisting of charging a capacitor (C15) to a potential, and discharging the capacitor for a discharge period through the tissue. The method further consists of measuring a voltage drop on the capacitor over the discharge period and determining the impedance of the tissue responsive to the potential, the voltage drop, and the discharge period.

Abstract: An implantable medical device configured to connect to function conductor(s) to transmit therapeutic signals or diagnostic signals or both. Includes a controllable voltage/current source or adjustable terminating impedance for the function conductor and a control unit that is connected to the voltage or current source or adjustable terminating impedance. The control unit controls a voltage, or a current to be applied to the function line, or to adjust the terminating impedance. Includes an interference field sensor connected to the control unit, and to detect an alternating electromagnetic or magnetic field, and to supply an output signal, upon detection. The control unit controls the voltage/current source as a function of the output signal of the interference field sensor, or sets the adjustable impedance so that a voltage induced as the result of an alternating electromagnetic or magnetic field is compensated for at the distal end of the electrode line.

Abstract: When a defibrillator selects a dosage of energy or current to be delivered to a patient, the defibrillator selects an excitation current frequency and applies the excitation current at the selected frequency to the patient. The frequency of the excitation current is selected as a function of the dosage to be delivered. The patient's response to the excitation current at the selected frequency will accurately reflect the impedance that the defibrillator will “see” when delivering the selected dosage of energy or current.

Abstract: This document discusses, among other things, an apparatus comprising, a plurality of electrodes configured to deliver defibrillation countershock energy to a subject, an impedance measurement circuit communicatively coupled to the electrodes and configured to measure the impedance between any two of the electrodes using a non-stimulating excitation signal, and a controller communicatively coupled to the impedance measurement circuit and configured to calculate the impedance of a shock vector, wherein the shock vector includes a first electrode and a second electrode electrically connected together, and a third electrode, and wherein the controller calculates the impedance using measured impedances between the three electrodes when none of them are electrically connected.

Abstract: Embodiments of the present concept are directed to external defibrillators that include an electrode connection port having multiple connection options, and include a detection device to determine an electrode connection configuration so as to provide an appropriate electrical shock to a patient. The detection device detects the electrode connection configuration of a plug connector for connected electrodes to determine if the plug connector is in an adult orientation or a pediatric orientation. The external defibrillator is configured to a deliver an electrical shock with less energy when the pediatric orientation is detected rather than the adult orientation.

Abstract: A system for providing stimulation current in implantable medical devices is provided. One aspect of this disclosure relates to an apparatus including a power supply terminal adapted to be connected to a power supply. The apparatus embodiment also includes circuitry connected to the power supply terminal and adapted to detect a parameter dependent on tissue/electrode impedance. The apparatus embodiment further includes a current output pulse generator adapted to deliver electrical therapy. The current generator includes an adjustable compliance voltage source connected to the power supply terminal. The compliance voltage source has a programmable amplitude and is adapted to provide different potentials for different tissue/electrode interface impedances. According to various embodiments, the apparatus embodiment also includes at least one stimulating electrode, and the current generator is adapted to deliver electrical therapy using the electrode. Other aspects and embodiments are provided herein.

Abstract: A defibrillator includes a defibrillator mainframe and a defibrillating electrode. The defibrillator mainframe includes a main control unit and a master device electrically connected to the main control unit. The defibrillating electrode comprises a slave device supporting a bus protocol, the master device and slave device being interconnected through a bus.

Abstract: A method for determining a cardiac shock strength, for example the programmed first-therapeutic shock strength of an implantable cardioverter defibrillator (ICD), including the steps of sensing a change in a T-wave of an electrogram with respect to time such as the maximum of the first derivative of a T-wave of an electrogram; delivering a test shock by (i) delivering a test shock at a test-shock strength and at a test-shock time relating to the maximum of the first derivative of the T-wave with respect to time; and (ii) sensing for cardiac fibrillation. If fibrillation is not sensed, test-shock delivery is repeated at the same test-shock strength and at specific, different test-shock times relating to the maximum of the first derivative of the T-wave. If fibrillation is still not sensed, the shock strength is decreased and test shocks are repeated at the same specific test shock times relative to the maximum of the first derivative of the T-wave.

Abstract: A method of screening for breast cancer, including determining at least one first electrical impedance related characteristic for a first breast of a patient, determining at least one second electrical impedance related characteristic for a second breast of a patient and classifying the patient as requiring additional testing, responsive to the value of the first and second characteristics, wherein classifying is not based on a difference between the first and second characteristics.

Abstract: An external defibrillator having a battery; a capacitor electrically communicable with the battery; at least two electrodes electrically communicable with the capacitor and with the skin of a patient; a controller configured to charge the capacitor from the battery and to discharge the capacitor through the electrodes; and a support supporting the battery, capacitor, electrodes and controller in a deployment configuration, the defibrillator having a maximum weight per unit area in the deployment configuration of 0.1 lb/in2 and/or a maximum thickness of 1 inch. The support may be a waterproof housing.

Abstract: A load detecting circuit has a primary side and a secondary side with a secondary side patient load impedance input having a patient-side opto-isolator and a secondary side reference resistance load input having a reference-side opto-isolator coupled to the secondary side patient load impedance input. The circuit also includes at least one primary side output resistor, wherein the patient-side opto-isolator and the reference-side opto-isolator drive the at least one primary side output resistor and an integrator for operatively controlling the secondary side and conveying the patient load input and the reference load input to the primary side, where the patient load input and the reference load input are powered by a secondary side transformer winding.

Abstract: Methods and apparatus for accurately and painlessly measuring the impedance between defibrillation electrodes implanted in a patient utilize a high current test pulse delivered with a sufficiently high current to produce an accurate measurement of the defibrillation electrode impedance while limiting the duration of the test pulse such that the pain sensing cells in the patient do not perceive the test pulse. In one embodiment, the test pulse is generated from the high voltage transformer without storing energy in the high voltage capacitors and is delivered to the defibrillation electrodes in the patient utilizing the high voltage switching circuitry.

Abstract: The invention relates to a method and arrangement for determining a power supply state variable, particularly of the maintenance state of a battery or rechargeable battery, in an active medical implant, wherein the power supply is subjected to a predetermined load, and the output voltage thereof is detected multiple times during at least one time segment of the load phase, and the measurement values are subjected to a comparison to a respective comparison value, or the chronological curve of the voltage obtained from the measurement values is subjected to a comparison to at least one comparison curve, wherein the comparison result is considered characteristic for the state variable.

Abstract: Techniques are provided for detecting heart failure or other medical conditions within a patient using an implantable medical device, such as pacemaker or implantable cardioverter/defibrillator, or external system. In one example, physiological signals, such as immittance-based signals, are sensed within the patient along a plurality of different vectors, and the amount of independent informational content among the physiological signals of the different vectors is determined. Heart failure is then detected by the implantable device based on a significant increase in the amount of independent informational content among the physiological signals. In response, therapy may be controlled, diagnostic information stored, and/or warning signals generated. In other examples, at least some of these functions are performed by an external system.

Abstract: A defibrillator includes a defibrillator mainframe and a defibrillating electrode. The defibrillator mainframe includes a main control unit and a master device electrically connected to the main control unit. The defibrillating electrode comprises a slave device supporting a bus protocol, the master device and slave device being interconnected through a bus.

Abstract: A device and method for defrosting a defibrillation electrode are provided. This includes an automated external defibrillator that is capable of defrosting one or more frozen electrodes. The device is includes a portable housing containing a battery powered energy source and a controller as well as at least a pair of electrodes which are operably coupled to the housing. The electrodes are designed for attachment to the chest of a patient in need of resuscitation and contain a conductive interface medium that has temperature dependent properties. A controller is configured to selectively heat the conductive interface medium by applying limited electrical impulses and raise the electrode temperature to a desired temperature range.

Abstract: Visualization of a probe when impedance-based measurement technology is being used is improved by stabilizing a displayed image of the probe or catheter. Using a model of reasonable probe shapes and a matching algorithm, an erroneous probe image is adjusted so that it assumes a realistic shape on a display. A range of positional variations is also incorporated in the model. When an apparent probe position exceeds a permissible range of motion, the probe image is constrained to a realistic position.

Abstract: Techniques for diagnosing lead fractures and lead connection problems are described. One or more medical leads may be coupled to an implantable medical device (IMD) to position electrodes or other sensors at different locations within a patient than the IMD. The IMD may include a lead diagnostic module configured to diagnose problems with a coupled lead and automatically select between a lead fracture problem and a lead connection problem based on the diagnosis. The diagnosis of either lead fracture problems or lead connection problems may be based on a timing of an increased impedance value with respect to connection of the lead to the IMD, a return to baseline impedance values after the increased impedance value, an abrupt rise of the increased impedance value, maximum impedance values, or oversensing. An external device may present the diagnosis to a user to facilitate appropriate corrective action.

Abstract: Embodiments relate to an implantable cardiac system, including a housing, electronic circuitry for controlling one or more of power management, processing unit, information memory and management circuit, sensing and simulation output. The system also includes diagnosis and treatment software for diagnosing health issues, diagnosing mechanical issues, determining therapy output and manage patient health indicators over time, a power supply system including at least one rechargeable battery, a recharging system, an alarm (or alert) system to inform patient of energy level and integrity of system, communication circuitry, one or more electrodes for delivering therapeutic signal to a heart and one or more electrodes for from delivering electrocardiogram signal from the heart to the electronic circuitry. The power sources can include rechargeable batteries.

Abstract: A method for operating an automatic external defibrillator (AED) prompts an operator about proper operation of the automatic external defibrillator and placement of the electrodes to ensure rapid and proper operation. Depending upon a state of a pad storage compartment, upon activation the AED issues an initial prompt, pauses after the initial prompt and then issues a second prompt. The AED also determines whether the pads have been removed from a liner and if so, issues a pad application prompt. The AED next determines whether both pads have been placed and if so, analyzes an impedance signal and if the impedance signal is erratic, issues a pad correction prompt. The AED also issues the pad correction prompt if the pads are removed from the liner but never go on the patient.

Abstract: An implantable medical device configured to connect to function conductor(s) to transmit therapeutic signals or diagnostic signals or both. Includes a controllable voltage/current source or adjustable terminating impedance for the function conductor and a control unit that is connected to the voltage or current source or adjustable terminating impedance. The control unit controls a voltage, or a current to be applied to the function line, or to adjust the terminating impedance. Includes an interference field sensor connected to the control unit, and to detect an alternating electromagnetic or magnetic field, and to supply an output signal, upon detection. The control unit controls the voltage/current source as a function of the output signal of the interference field sensor, or sets the adjustable impedance so that a voltage induced as the result of an alternating electromagnetic or magnetic field is compensated for at the distal end of the electrode line.

Abstract: A defibrillator for external application to a patient. The defibrillator includes a power storage unit for supplying a defibrillation shock. The power storage unit has a capacitor unit encompassing at least one capacitor. In order to adjust a defibrillation treatment to different patients, the defibrillator advantageously comprises several different capacitor units which have a capacity adapted to various patient impedances and are or can be coupled in a replaceable manner to the defibrillator.

Abstract: A process for determining whether the location of a stimulation electrode meets a selected heart performance criteria includes providing stimulation to the heart through the electrode and obtaining an impedance measurement during stimulation delivery using an impedance sensing vector formed by electrodes that do not include the stimulation electrode. The impedance measurements are processed, either alone or in combination with an electrogram, also obtained during stimulation, to obtain a measure of hemodynamic performance.

Abstract: An implantable electronic therapy device, having a therapy unit, a heart rate capturing unit, a contractility determination unit, and an evaluation and control unit. The therapy unit delivers an antitachycardiac therapy. The heart rate capturing unit determines a ventricular heart rate from an input signal, and the contractility determination unit generates from an input signal, a contraction signal reflecting a contractility of a ventricle. The evaluation and control unit is connected to the therapy unit, the heart rate capturing unit, and the contractility determination unit actuates the therapy unit to administer an antitachycardiac therapy when the heart rate capturing unit detects an increase in the heart rate above a specified threshold value and the contractility determination unit supplies a contraction signal which is not physiologically adequate for the increase in the heart rate.

Abstract: An apparatus and techniques for determining whether a medical electrode, such as a defibrillation electrode coupled to an automated external defibrillator, is in a condition for replacement. The determination can be made as a function of one or more data. In one exemplary embodiment, the determination is a function of one or more measurements of an impedance of a hydrogel bridge in a test module. In another exemplary embodiment, the determination is a function of one or more environmental condition data from one or more environmental sensors.

Abstract: Embodiments of the invention include an implantable medical device having a digital signal processing circuit associated with an implantable medical device function. The digital signal processing circuit can be selectively implementable according to the clinical need of a patient. Embodiments of the invention also include methods of making and using such implantable medical devices.

Abstract: A defibrillator system and associated methodology for determining capacity of a battery and/or a number of battery cells contained in a pack. The system measures and stores the battery or battery pack voltage signal data and uses an algorithm to determine the remaining capacity. The algorithm takes into account the operating mode of the device, historical information of the device including, but not limited to, how long it has been since the device has been used, how the device has been used (e.g. shocking mode or idle mode), how many times the device has been used with its installed battery or battery pack, how many charging cycles and/or shocks have been delivered etc. The output from the system is fed back to the user to inform the user when the battery is low, needs to be replaced and/or how many remaining shocks are left the battery.

Abstract: An automatic external defibrillator is shipped from the manufacturer with the battery installed in the battery compartment of the AED. During shipment a removable tab is located between a battery terminal and an electrical contact inside the battery compartment. Upon receipt of the AED the user pulls the tab to remove it from the battery compartment. This completes the circuit between the AED and its battery and the AED begins a self-test. A packaging panel covers the controls of the AED to prevent actuation of controls during the self-test. The packaging panel includes instructions for setup of the AED including indication of a control to actuate during or at the conclusion of the self-test.

Abstract: A method and apparatus for determining a T-wave shock interval sense a cardiac electrogram (EGM) signal comprising a T-wave signal. A T-wave center is determined from the EGM signal, and a T-wave shock interval is determined in response to determining the T-wave center. A T-wave shock is delivered at the T-wave shock interval computed based on the T-wave center.

Abstract: An exemplary method includes detecting fibrillation, measuring impedance of a defibrillation circuit that includes myocardial tissue, determining one or more defibrillation shock parameters based at least in part on the impedance, delivering a defibrillation shock using the one or more defibrillation shock parameters and, if the shock was unsuccessful, adjusting a membrane time constant and determining one or more new defibrillation shock parameters based at least in part on the adjusted membrane time constant. Various other exemplary methods are disclosed as well as various exemplary devices, systems, etc.

Abstract: A cardiac rhythm management device predicts defibrillation thresholds without any need to apply defibrillation shocks or subjecting the patient to fibrillation. Intravascular defibrillation electrodes are implanted in a heart. By applying a small test energy, an electric field near one of the defibrillation electrodes is determined by measuring a voltage at a sensing electrode offset from the defibrillation electrode by a known distance. A desired minimum value of electric field at the heart periphery is established. A distance between a defibrillation electrodes and the heart periphery is measured, either fluoroscopically or by measuring a voltage at an electrode at or near the heart periphery. Using the measured electric field and the measured distance to the periphery of the heart, the defibrillation energy needed to obtain the desired electric field at the heart periphery is estimated. In an example, the device also includes a defibrillation shock circuit and a stimulation circuit.

Abstract: Aspects of the present invention relate to automatic impedance measurements between one or more electrodes in a set of electrodes that may be associated with a lead of an implanted device. A voltage measurement that is associated with a stimulation pulse between the two electrodes may be made. The voltage measurement may be used to determine the impedance between the two electrodes. The impedance measurement may be made for each possible pair of electrodes in the set of electrodes. The impedance measurements may be displayed to a clinician on a user interface.

Abstract: Systems and methods are provided for estimating a patient's ventricular defibrillation threshold (VDFT). Stimulation pulses, which are of at least three different energy levels up to 2 Joules, are delivered to the patient's right ventricle during a window defined between an R-wave and a vulnerable period that follows the R-wave. Voltage potentials, induced in response to the delivered RV stimulation pulses, are measured at a location of the patient's left ventricle (LV) where it is predicted that potential gradients induced in response to RV stimulation pulses will be lowest. Potential gradients are computed using the measured voltage potentials. The patient's VDFT can then be estimated by estimating, based on the computed potential gradients, the RV stimulation energy level that would be required to achieve a minimum acceptable potential gradient at the location of the patient's LV where it is predicted that potential gradients induced in response to RV stimulation pulses will be lowest.

Abstract: According to an aspect of the present disclosure, an automatic external defibrillator configured to deliver electrical pulses and/or shocks to a heart of a patient during a cardiac emergency is provided and includes a housing supporting an electrical connector; a defibrillator electrode delivery system supported on the housing; and a pair of defibrillation electrode pads supported by the defibrillator electrode delivery system. Each of the pair of defibrillation electrode pads is pre-connected to the electrical connector of the housing. A hydrogel layer of each defibrillation electrode pad is retained by the defibrillator electrode delivery system in such a manner so as to reduce a moisture vapor transmission rate thereof.

Abstract: Implantable medical device power circuits are disclosed. Multiple batteries may be provided, along with a number of switches, enabling a plurality of battery and power circuit configurations to be defined. Configurations of the power circuit may be changed in response to changes in battery status as the batteries are used and/or near end-of-life. Configurations of the power circuit may also be performed in response to changes in device operation. Methods associated with operating such circuits and implantable medical devices are also disclosed.

Abstract: A method is provided, including identifying that a subject is at risk of suffering from atrial fibrillation (AF). Responsively to the identifying, a risk of an occurrence of an episode of the AF is reduced by applying an electrical current to a site of the subject selected from the group consisting of: a vagus nerve, a sinoatrial (SA) node fat pad, a pulmonary vein, a carotid artery, a carotid sinus, a coronary sinus, a vena cava vein, a jugular vein, an azygos vein, an innominate vein, and a subclavian vein, and configuring the current to stimulate autonomic nervous tissue in the site. Other embodiments are also described.

Abstract: The invention presents an apparatus and techniques for determining whether a medical electrode, such as a defibrillation electrode coupled to an automated external defibrillator, is in a condition for replacement. The determination can be made as a function of one or more data. In one exemplary embodiment, the determination is a function of one or more measurements of an impedance of a hydrogel bridge in a test module. In another exemplary embodiment, the determination is a function of one or more environmental condition data from one or more environmental sensors.