Abstract: A method, including inserting a probe into a cavity in a subject's body and receiving, from a force sensor in the probe, first readings indicative of a first change in measured contact forces between the probe and the cavity by less than a predetermined limit over at least a predetermined interval of time. The method continues by receiving second readings from the force sensor when the second readings have changed by more than a predetermined force threshold or location coordinates of the probe have changed by at least a predetermined location change threshold. The method continues by receiving third readings indicative of a second change in the measured contact forces between the probe and the cavity by less than the predetermined limit over at least the predetermined interval of time. The method concludes by calibrating a zero-force point for the force sensor according to the third readings.

Abstract: A differential or relative measurement between an orthogonal measurement vector and another measurement vector can be used to determine the location where fluid accumulation is occurring or the local change in such fluid accumulation. This can help diagnose or treat infection or hematoma or seroma at a pocket of an implanted cardiac rhythm management device, other implanted medical device, or prosthesis. It can also help diagnose or treat pulmonary edema, pneumonia, pulmonary congestion, pericardial effusion, pericarditis, pleural effusion, hemodilution, or another physiological condition.

Abstract: Methods and systems for monitoring the well-being of a target are disclosed. In a method embodiment, data representing a signal is received by a computer system. The signal may be generated at least in part by one or more sensors in response to the detection of a change in an electrical field, electric potential, capacitance, and/or dielectric constant of a target spaced apart from the one or more sensors. The method may further include identifying, using the computer system and based at least in part on the data electronically received by the computer system, a recurring pattern in the received data. The method may also include determining, using the computer system and based at least in part on the received data, whether a deviation from the recurring pattern transgresses a threshold. The deviation may comprise a subset of the data electronically received by the computer system.

Abstract: Methods and apparatus combine patient measurement data with demographic or physiological data of the patient to determine an output that can be used to diagnose and treat the patient. A customized output can be determined based the demographics of the patient, physiological data of the patient, and data of a population of patients. In another aspect, patient measurement data is used to predict an impending cardiac event, such as acute decompensated heart failure. At least one personalized value is determined for the patient, and a patient event prediction output is generated based at least in part on the personalized value and the measurement data. For example, bioimpedance data may be used to establish a baseline impedance specific to the patient, and the patient event prediction output generated based in part on the relationship of ongoing impedance measurements to the baseline impedance. Multivariate prediction models may enhance prediction accuracy.

Abstract: An apparatus comprises a catheter comprising a first electrode. The apparatus also comprises a second electrode electrically attached to a person and coupled to the first electrode via the person's tissue. Logic is coupled to the electrodes and generates an electrical signal that is provided through the electrodes and computes an impedance or conduction velocity associated with the electrodes based on the electrical signal. The logic stores a threshold against which said computed impedance or conduction velocity is compared by said logic.

Abstract: The invention relates to an electrophysiological analysis system which comprises a plurality of electrodes (E1-E4), power supply means (10, 30) for successively applying a substantially continuous voltage ranging approximately from 1 to 5 volts and lasting from 0.1 to 5 seconds to different slotted electrode pairs, collecting and storing means (450) for recording the variation of a current flow in the electrode pairs to which said voltage slots are applied, means (50) for enabling the current variations obtained by comparison between at least two current variations caused by supposed identical conditions and means (50) for comparing data related to the current variations recorded for several electrode pairs and enabled with reference data. Said invention can be used for chronoamperometrically detecting pathologies, pathological areas and organ dysfunctions.

Abstract: A device for measuring impedance of biological tissue may include electrodes and a voltage-to-current converter coupled to the electrodes to drive an alternating current (AC) through the tissue and sense an AC voltage. The converter may include an amplifier having first and second inputs and an output, a first voltage divider coupled to the first input, a second voltage divider coupled to the second input, a filter capacitor coupled between the output and the second voltage divider, a current limiting resistor coupled between the second input the second voltage divider, and a bypass capacitor coupled to the second input of the amplifier and in parallel with the resistor. A single-ended amplitude modulation (AM) demodulator may demodulate the AC voltage and generate a corresponding baseband voltage representing the impedance. The device may also include an output circuit to generate output signals representative of DC and AC components of the baseband voltage.

Abstract: A method to determine presence of a disease condition in a medical patient by evaluating conductivity information. Point-attributes values obtained from highly accurate conductivity data-sets taken as a function of time, over a period of time, are compared to previously determined threshold values. Z-scores may be determined to combine a plurality of point-attribute values in formulation of a composite score for a patient. Sometimes, z-scores are weighted by overall accuracy of the point-attribute in predicting presence of the disease.

Abstract: Implantable medical devices switch from a constant current mode of operation to a constant voltage mode of operation. The switching may be based on the device determining that tissue impedance stability has occurred. The determination may be a measurement of output voltage stability of the constant current source or based on other factors such as an amount of time that has elapsed. The switching may be as the result of an externally generated request such as by a clinician via an external device. The implantable medical device may begin constant voltage mode by utilizing stimulation parameters based on those initially programmed for constant current mode and based upon a measurement of voltage amplitude being output by the constant current source prior to the switch.

Abstract: An apparatus for assessing muscle quality includes a first acquisition unit that acquires bioelectric information including at least one of (i) a resistance component and a reactance component of bioelectrical impedance and (ii) first impedance measured by supplying alternating current at a predetermined low frequency to a living organism and second impedance measured by supplying alternating current at a predetermined high frequency to the living organism; a second acquisition unit that acquires a physical parameter related to physique of the living organism; and a calculation unit that calculates an index in accordance with a proportion, in muscle tissue, of muscle fiber to interstitial tissue based on the physical parameter and on at least one of a first parameter represented as a ratio between the resistance component and the reactance component and a second parameter represented as a ratio between the first impedance and the second impedance.

Abstract: The present invention provides various systems, a kit, and a method for accessing, sampling within, and visualization of areas within the mediastinal cavity for assisting a surgeon in performing a mediastinoscopy procedure. The access system includes one or more preferably toroidal balloons that can be expanded to dilate and protect the inner walls of a bodily conduit. Instruments pass through hollow spaces within the expanded toroidal balloons. The proximally positioned balloons are expanded first and the unexpanded balloons to be positioned distally are passed through them and subsequently expanded. The sampling system includes an instrument with a rounded head having two or more jaws and a slit therein at the distal end of an elongated tubular body. The visualization system includes a 360° camera that can be positioned from proximal to distal a target site and can also do a U-turn about its axis of extension.

Abstract: A method for characterization of a patient's esophagus may include receiving data measured by an impedance and high resolution manometry catheter in an esophagus in which the data may be representative of a pressure and/or an impedance associated with a swallowing event. The method may also include determining a cross-sectional area of the esophagus based on the received data and a pre-determined amount of a bolus consumed during the swallowing event. Systems and apparatus for characterizing a patient's esophagus may also include measuring data with a high resolution manometry catheter to determine the cross-sectional area, work, and compliance of the esophagus as a function of time during a swallowing event. Averaged data may establish a database of normal values for work done and compliance and allow for comparison of a patient to normal pathology.

Abstract: A device for measuring sural nerve conduction velocity and amplitude, the device comprising: a housing; stimulation means mounted to the housing for electrically stimulating a human sural nerve; a biosensor releasably mounted to the housing, the biosensor comprising a plurality of electrodes for detecting a sural nerve response evoked by the stimulation means; acquisition means mounted to the housing and electrically connected to the biosensor for electrically acquiring the sural nerve response detected by the biosensor; detection means mounted to the housing and electrically connected to the stimulation means and the acquisition means for detecting shorting or shunt of the stimulation current on the surface of the skin; processing means mounted to the housing and electrically connected to the acquisition means for digitizing, processing and storing the acquired sural nerve response; calculation means mounted to the housing and electrically connected to the processing means for calculating the conduction v

Abstract: A biopsy sampling device has an inner trocar having a sampling opening, an outer needle with 4 or more electrodes on it, an impedance measuring apparatus coupled to drive current through a first and a second electrode, while measuring voltages through a third and fourth electrodes to measure an impedance of tissue adjacent to the electrodes, the inner trocar slideably engaged within the central cavity of the outer needle such that its sharpened tip and sampling opening can protrude from an end of the outer needle and be removed to capture a sample in the sampling opening. The device is used to obtain biopsy samples by advancing the device into an organ while observing impedance of tissue near or adjacent the device before the operator withdraws the trocar to obtain a biopsy sample of an inclusion in the organ.

Abstract: The present invention relates to a sensor and device incorporating said sensor for obtaining data useful to determine the functional characteristics of the cornea in a non-invasive manner, particularly for establishing a correlation between the impedance at different frequencies and the permeability of the endothelium and epithelium and stromal hydration level.

Abstract: The present invention provides impedance data having an improved spatial resolution, both with regard to depth and lateral extension, which enables a detection of diseased skin conditions, such a malignant melanoma, at an early stage. Specifically, the present invention is implemented in a probe, medical devices and medical systems including such a probe, and methods using such a probe for measuring electrical impedance of tissue of a subject. A switching circuit is arranged for selectively activate electrode pairs of the probe in accordance with a predetermined activation scheme, the predetermined activation scheme including to activate adjacent electrodes in a successive manner, to gradually scan tissue of the subject at a first tissue depth so as to obtain a sequence of impedance signals from the tissue depth.

Abstract: A system and method for positioning an electrode for cardiotherapy of atrial arrhythmia are described. Signals from patient electrical activity for a plurality of electrode locations on a patient are analyzed. An electrode can be repositioned to different locations on the patient to obtain signals from patient electrical activity therefrom. A human perceptible output indicative of the quality of the signals for the plurality of locations is generated and a final electrode location on the patient for placement of the electrode for cardiotherapy is identified based on the human perceptible output.

Abstract: A surgical system kit is described. The surgical system kit includes a peripheral electrode, a surgical access instrument configured to be placed in a surgical target site, and a control unit. The surgical access instrument has a body with a proximal end, and a distal end, two or more electrodes on the distal end at fixed locations and spaced apart a known distance. The control unit is configured to send a signal to the peripheral electrode, receive information indicative of a neural response from at least one electrode of the surgical access instrument, and interpret the information according to a nerve conduction velocity modality to measure the nerve conduction velocity through the segment of the nerve.

Abstract: A system for detecting the presence of a nerve within a subject includes a stimulator configured to provide a stimulus to a portion of the subject, a sensing device configured to be placed in communication with a muscle of the subject and to generate an output signal corresponding to a monitored parameter of the muscle, the sensing device including a mechanical sensor configured to monitor a mechanical parameter of the muscle, and a receiver configured to receive the output signal from the sensing device and to determine if the output signal corresponds to the stimulus provided by the stimulator.

Abstract: A catheter and catheter system can use energy tailored for remodeling and/or removal of target material along a body lumen, often of atherosclerotic material of a blood vessel of a patient. An elongate flexible catheter body with a radially expandable structure may have a plurality of electrodes or other electrosurgical energy delivery surfaces to radially engage atherosclerotic material when the structure expands. An atherosclerotic material detector system may measure and/or characterize the atherosclerotic material and its location, optionally using impedance monitoring.

Abstract: An arrangement (100) is for creating body composition images of a body part by placing the apparel (101) in direct contact with the desired body part. The results of the image are shown on separate mobile devices (102), such as e.g. a mobile phone, tablet computer or similar device. The image and derivative information can be calculated on the mobile device (102) or with external computation resources.

Abstract: A method for determining brain state has the steps of attaching at least 2 first electrodes to the scalp of a subject at a separation, transmitting an electrical current between the at least 2 first electrodes, and measuring a first impedance between the at least 2 first electrodes to provide a resulting impedance. One embodiment has the further step of comparing the resulting impedance to pre-stored impedance measurements of the scalp to determine normal or pathological state. A further embodiment has the steps of attaching 2 first electrodes to the scalp of a subject at a separation and 2 second electrodes, transmitting a current between the first electrodes and measuring a first impedance between the second electrodes to provide a resulting impedance. The electrodes may be driven shield electrodes, and the method may further include comparing impedance measurements to pre-stored impedance measurements to determine normal and pathological state.

Abstract: The present disclosure provides a method and system for stimulating and monitoring intensity of pain experienced by one or more users. The method includes measuring the intensity of pain experienced by the one or more users on a pre-determined scale and augmented chart or physician's personal assessment using a plurality of one or more bio-markers, determining co-relation between the plurality of one or more bio-markers and the intensity of pain experienced by the one or more users, refining the co-relation between the plurality of one or more bio-markers and the intensity of pain experienced by the one or more users by learning from responses of one or more similar users, generating a pain profile for each of the one or more users and utilizing the learned information and the generated profile for monitoring, evaluating and treating the one or more users.

Abstract: Techniques for estimating a cardiac chamber or vascular pressure based upon impedance are described. A device or system may measure an impedance between at least two electrodes implanted within or proximate to a cardiovascular system. The device or system may estimate a pressure of an element of the cardiovascular system based on a relationship between impedance and volume of the element, and based on a empirical relationship between the volume and the pressure. The device or system may also estimate the dimension of the element based on the impedance-volume relationship, or other characteristics based on the impedance. Because the impedance measurements may be obtained, in some examples, by using electrodes and leads implanted within the cardiovascular system and coupled to an implantable medical device, a practical estimation of a cardiovascular pressure can be obtained on a chronic basis without requiring the use other invasive sensors, such as micronanometer transducers.

Abstract: A method for accurate pain analysis using a combination of electrodermal data and self-report information is described. To obtain pain measurements, electrodermal activity is collected and analyzed. One or more biosensors obtain electrodermal data from a person. The electrodermal data is filtered to produce skin conductance values. The skin conductance values are associated with self-report pain information from a person over multiple time regions. The associating allows electrodermal activity to be related to self-reported pain (SRP) data to derive an objective pain measurement.

Abstract: The invention relates to a medical diagnostic device (1) having at least one sensor matrix (2) for capturing electrical voltage signals at a plurality of locations on the body surface of a person or animal, wherein the diagnostic device (1) is set up for capturing a signal (12) representing the position of the sensor matrix (2) relative to the body of the person or animal, and for determining position information (14) about the position of the sensor matrix (2) relative to the body, localized image information (13) is determined from the voltage signals, and the localized image information (13) is associated with the position information (14).

Abstract: A bioelectrical impedance measuring apparatus may include an impedance measuring unit configured to provide an inspection current based on a predetermined current to a living body, and obtain an inspection voltage corresponding to an impedance of the living body, an amplification unit configured to amplify the inspection voltage with reference to a correction voltage, an AD converter configured to AD-convert an output of the amplification unit, and a control unit configured to control the inspection current and the correction voltage based on an AD-converted result of the AD converter such that the output of the amplification unit is within an input dynamic range of the AD converter, and calculate an impedance average of the living body and an impedance variation of the living body based on the predetermined current, the correction voltage and the AD-converted result.

Abstract: A catheter system for controlled sympathectomy procedures is disclosed. A catheter system for controlled micro ablation procedures is disclosed. Methods for performing a controlled surgical procedure are disclosed. A system for performing controlled surgical procedures in a minimally invasive manner is disclosed.

Abstract: A system comprising a biometric monitoring device including a housing including a platform to receive at least one foot of the user, a body weight sensor to generate body weight data, processing circuitry to calculate user weight data which corresponds to the user's weight, using the body weight data, and communication circuitry to: (a) receive user identification data which identifies the user or a portable activity monitoring device, and (b) transmit the user weight data to data storage associated with the user identification data. The system further includes the portable activity monitoring device including a housing having a physical size and shape that is adapted to couple to the user's body, a sensor to generate sensor data, and communication circuitry to receive physiologic data which is based on the user weight data, and processing circuitry to calculate activity data using the sensor data and physiologic data.

Abstract: In particular embodiments, a method includes generating a 3D display of an avatar of a person, where the avatar can receive inputs identifying a type of a physiological event, a location of the physiological event in or on a person's body in three spatial dimensions, a time range of the physiological event, a quality of the physiological event, and rendering the physiological event on the avatar based on the inputs.

Abstract: A catheter and catheter system can use energy tailored for remodeling and/or removal of target material along a body lumen, often of atherosclerotic material of a blood vessel of a patient. An elongate flexible catheter body with a radially expandable structure may have a plurality of electrodes or other electrosurgical energy delivery surfaces to radially engage atherosclerotic material when the structure expands. An atherosclerotic material detector system may measure and/or characterize the atherosclerotic material and its location, optionally using impedance monitoring.

Abstract: The present invention provides a root canal length measuring apparatus and a root canal treatment apparatus which can acquire a position of a measurement electrode with high reproducibility in the same root canal. The root canal length measuring apparatus includes a measurement electrode which is inserted into a root canal, an oral electrode which is held in an oral cavity, a measuring section which applies an electric measuring signal between the measurement electrode and the oral electrode and specifies an apex position so as to measure a root canal length, a memory means which stores position data corresponding to a position of the measurement electrode in a root canal acquired by the measuring section, and an operating means which instructs the memory means to store the position data.

Abstract: Systems and methods for monitoring pulmonary edema or other thoracic fluid status in a subject use thoracic impedance histogram information. An internal or external processor circuit receives the thoracic impedance histogram information and uses it to compute and provide a lung fluid status indication. The thoracic impedance histogram information can include a count, mean or median of a histogram bin or subrange of bins within the histogram range.

Abstract: A body composition measuring apparatus for calculating one or multiple types of body composition data is provided with a CPU configured to perform the following processes. The CPU sets second information indicating physical characteristics of a human subject. The CPU measures the bioelectrical impedance of the human subject by a voltage measurement circuit. The CPU obtains at least one piece of first information from each of at least one recording medium having recorded thereon the at least one piece of the first information necessary for calculating body composition data indicating a particular type of body composition, and calculates body composition data indicating a type of body composition corresponding to each of the at least one piece of the first information based on the at least one piece of the first information obtained by the information obtainer, the second information, and the bioelectrical impedance.

Abstract: Proposed is a method of multichannel GSR detection for improving measurement accuracy and noise/artifact rejection in measurement of the galvanic skin response on the skin of an individual. The method comprises multichannel GSR signal detection with at least two electrode pairs that are attached to a body of an individual in contact with the skin in different locations, wherein the GSR signals are measured and recorded while the level of excitation of the nervous system of the individual varies. The method is based on the fact that only events that show high temporal correlation in two or more signal registration channels are considered to be physiological GSR reactions. Time-domain correlation allows not only improved detection of high-amplitude events but also improved sensitivity to smaller events that were ignored in standard bipolar GSR recording.

Abstract: The invention provides an electrophysiological analysis system, in particular for detecting pathological states. This system comprises: electrodes intended to be placed in different regions of the body that are well away from each other; an adjustable DC voltage source for generating successive DC voltage pulses varying in magnitude from one pulse to another, the duration of the pulses being equal to or greater than about 0.2 seconds; a switching circuit for selectively connecting a pair of active electrodes to the voltage source and for connecting at least one other high-impedance electrode; and a measurement circuit for recording data representative of the current in the active electrodes and potentials on at least certain high-impedance connected electrodes in response to the application of said pulses. The range of voltages covered causes, from one pulse to another, the appearance or disappearance of electrochemical phenomena in the vicinity of the active electrodes.

Abstract: Devices and systems to measure luminal organ parameters using impedance. In at least one embodiment of an impedance device of the present disclosure, the impedance device comprises an elongated body having a distal body end and a pair of detection electrodes positioned in between a pair of excitation electrodes located at or near the distal body end, the pair of detection electrodes configured to obtain one or more conductance values within a mammalian luminal organ within a field generated by the pair of excitation electrodes, wherein a measured parameter of the mammalian luminal organ can be calculated based in part upon the one or more conductance values obtained by the device and a known distance between the pair of detection electrodes.

Abstract: Devices and methods are disclosed for detecting and/or monitoring cerebral pathologies. In one embodiment, a cerebro-hemodynamic measurement apparatus is disclosed that includes at least one processor. The at least one processor is configured to receive, via at least one sensor, at least one signal associated with a brain of a subject. The at least one processor is configured to determine, based on the at least one signal, a change in cerebral blood volume caused by a cardiac pulsation. The at least one processor is configured to determine, based on the at least one signal, a change in intracranial pressure due to cardiac pulsation. The at least one processor is also configured to estimate mean intracranial pressure based on changes in the cerebral blood volume, changes in the intracranial pressure, and a compliance indicator.

Abstract: A method comprising measuring skin conductivity level of a human subject responsive to a series of preliminary questions; measuring skin conductivity level of the human subject in response to a series of control questions; and in case that a sympathetic activation is detected, finding the authenticity of the response to the control question by comparing the recovery time of skin conductivity level for the control question with the basic recovery time. Further, a method comprising measuring heartbeat of a human subject responsive to a series of preliminary questions to which the answer is known, to derive a level of coherence of the heartbeat being a baseline heartbeat coherence level; presenting the human subject with a series of control questions, and finding the authenticity of a response to a relevant question by comparing the heartbeat coherence detected with the baseline heartbeat coherence and the unbalanced heartbeat coherence.

Abstract: A device for diagnosing a wound in a patient, the device comprising: at least two electrodes configured to be placed on the skin of the patient, wherein the at least two electrodes are placed in the vicinity of the wound; and at least one signal processor operatively coupled with the at least two electrodes, wherein the at least one signal processor is configured to: i) detect and record an endogenous alternating electrical signal in an area of the wound, ii) transform said endogenous alternating electrical signal into a voltage versus frequency spectrum using a Fast Fourier Transform (FFT) algorithm, and iii) diagnose the wound as a chronic wound if the voltage for a frequency between 65-200 Hz of the frequency spectrum is below 10?7.3±10% volts and as an acute wound if the voltage for a frequency between 65-200 Hz of the frequency spectrum is above 10?7.3±10% volts.

Abstract: An implantable medical device and associated methods monitor thoracic fluid status and discriminate thoracic fluid conditions. Intrathoracic impedance is measured along multiple intrathoracic measurement vectors using implanted electrodes. A map of thoracic conductivity is computed using the measured intrathoracic impedances. A thoracic fluid condition is detected in response to the computed map.

Abstract: Cell or tissue permeability to electrical signals can be used to determine the depth of anesthesia of a patient. A method and device is presented to measure, record and control the effects of anesthesia or analgesics on humans and/or animals. Based on impedance values of tissues measured at single, multiple, or a domain of frequencies, the system detects tissue permeability alterations as determined by electromagnetic, impedance, and/or dielectric spectroscopy. The system measures the permeability of tissues to electrical signals and correlates these values to the depth of anesthesia or sedation level of a certain tissue or individual. This method and device can be used to measure the effects of anesthesia or analgesic for either local or systemic administration.

Abstract: A method of detecting changes in biologically sourced electrical signals is disclosed. Biologically sourced electrical signals are coupled to a meta-stable and hair-trigger wise perturbable system. The system operates in a first oscillatory mode when the received signals have a strength below a first predetermined level and operates in a distinguishable second oscillatory mode when the received signals have strengths above the first predetermined level but below a second predetermined level. The strengths of the received and thusly distinguishable signals may be in a range below 10 picoAmperes. The biologically sourced electrical signals may be driven by intracranial nerve firings.

Abstract: An electrical stimulation device and method of locating an electrical stimulation point of a human or animal. The device comprises a matrix of electrodes distributed on an electrode pad configured to be applied on a human or animal body and arranged for covering a plurality of the stimulation points of the human or animal. An electronic circuit is connected to the matrix of electrodes and configured for applying an electrical stimulation signal to the electrodes. A feedback signal, in response to an electrical stimulation signal, may be used in assessing the suitability of electrodes as an electrical stimulation point.

Abstract: Implantable medical devices and techniques are implemented that use bio-impedance to measure aspects of patient physiology. A signal separation method is performed at least in part in an implantable device. The method involves detecting a plurality of impedance signals using a plurality of implantable electrodes coupled to the implantable device. The method further involves separating one or more signals from the plurality of impedance signals using a signal separation technique, such as an algorithm-based separation technique.

Abstract: A device for measuring impedance of biological tissue may include a pair of electrodes for contacting the biological tissue, and a drive circuit coupled to the pair of electrodes and configured to drive an alternating current (AC) through the biological tissue and to sense an AC voltage. The AC voltage is towards a reference voltage on at least one of the pair of electrodes. The device may include at least one single-ended amplitude modulation (AM) demodulator configured to demodulate the AC voltage and to generate a corresponding baseband voltage representing the impedance, and an output circuit configured to generate output signals representative of DC and AC components of the baseband voltage.

Abstract: A method and a system for determining age of a user based on mass data are provided. The method includes: obtaining basic age data of the user, configuring an initial weight for the basic age data; obtaining an age weight of the user in different kinds of basic age data according to the initial weight and an age similarity of the user in the different kinds of basic age data; and searching the basic age data for an age with a largest age weight, determining the age with the largest age weight as an estimated age of the user. The method and system for determining age of the user based on mass data is able to improve accuracy of the determination of the age of the user.

Abstract: A device to measure tissue impedance comprises drive circuitry coupled to calibration circuitry, such that a calibration signal from the calibration circuitry corresponds to the current delivered through the tissue. Measurement circuitry can be coupled to measurement electrodes and the calibration circuitry, such that the tissue impedance can be determined in response to the measured calibration signal from the calibration circuitry and the measured tissue impedance signal from the measurement electrodes. Processor circuitry comprising a tangible medium can be configured to determine a complex tissue impedance in response to the calibration signal and the tissue impedance signal. The processor can be configured to select a frequency for the drive current, and the amount of drive current at increased frequencies may exceed a safety threshold for the drive current at lower frequencies.

Abstract: A system and method for assessing relative proportions of cholinergic and adrenergic nervous receptors in a patient is disclosed. The system includes: an anode, a cathode, and passive electrode for placement on different regions of the patient body. The method generally includes: applying DC voltage pulses of varying voltage values to stress sweat glands of the patient, collecting data representing the current between the anode and the cathode and the potential of the anode, the cathode, and the passive electrode for each of the different DC voltage, and computing data representing the electrochemical skin conductance of the patient. The computed data representing the electromechanical skin conductance of the patient is reconciled with reference data from control patients having known relative proportions of cholinergic and adrenergic nervous receptors. Thus, the relative proportions of cholinergic and adrenergic nervous receptors in the patient can be determined.

Abstract: Methods and devices for monitoring and/or treating patients comprise a switch to automatically start-up the device when the device contacts tissue. By automatically starting up the device, the device may be installed without the clinician and/or user turning on the device, such that the device can be easy to use. In many embodiments, the device comprises startup circuitry with very low current and/or power consumption, for example less than 100 pA. The startup circuitry can detect tissue contact and turn on circuitry that is used to monitor or treat the patient.