Abstract: An implantable sensor module includes a housing having an inner shell and an outer layer formed to extend over and enclose the inner shell to form an outer wall of the housing, the inner shell having a thickness extending between an inner wall of the inner shell and an outer wall of the inner shell, the outer layer having an inner side engaged against the outer wall of the inner shell and having a thickness extending between the inner side and the outer wall of the housing, wherein the inner shell and the outer layer form a substantially flat portion. A flexible diaphragm is formed within the inner shell and extends between a first edge and a second edge, and a shoulder extends adjacent to the first edge to extend the outer layer laterally away from a central medial line extending between the first and second edges of the diaphragm.

Abstract: An implantable medical device for detecting and treating an arrhythmia includes an optical sensor adapted for positioning adjacent to a blood-perfused tissue volume. In one embodiment for controlling arrhythmia therapies delivered by the device, the optical sensor is controlled to emit light in response to detecting an arrhythmia, detect light scattered by the volume of blood perfused tissue including measuring an optical sensor output signal corresponding to the intensity of scattered light for at least four spaced-apart wavelengths, and compute a volume-independent measure of tissue oxygen saturation from the detected light. The hemodynamic status of the arrhythmia is detected in response to the measure of tissue oxygen saturation.

Abstract: A method and medical device for detecting signals that detects emitted light scattered by a volume of tissue delivered along a first pathway at a plurality of wavelengths to generate corresponding first detected light intensity output signals, detects emitted light scattered by the volume of tissue delivered along a second pathway different from the first pathway at a plurality of wavelengths to generate corresponding second detected light intensity output signals, determines whether a difference between the emitted light detected along the first pathway and the emitted light detected along the second pathway is greater than a predetermined threshold, and alters sensing by the device in response to the determining whether a difference is greater than the predetermined threshold.

Abstract: An implantable medical device having a flexible diaphragm is provided with a housing including a shell and an outer layer. The flexible diaphragm extends along the shell. The outer layer has an outer surface and an inner surface. An adhesive coating is applied between the diaphragm and the inner surface of the outer layer. The outer layer includes a recess along the diaphragm for receiving the adhesive.

Abstract: In general, the invention is directed to methods and devices for determining an ion concentration in the extracellular fluid of a patient. As examples, the ion may be one or more of potassium, sodium, chloride, or calcium. A system includes an electrode deployed in or near a tissue, such as a skeletal muscle, of the patient. A pulse generator supplies one or more stimulations to the tissue, and a sensor, such as an accelerometer, detects the response of the tissue to the stimulations. A processor determines a concentration of ions in the extracellular fluid as a function of the response. The system may detect an ion imbalance based upon the determined concentration of ions.

Abstract: In general, the invention is directed to methods and devices for determining an ion concentration in the extracellular fluid of a patient. As examples, the ion may be one or more of potassium, sodium, chloride, or calcium. A system includes an electrode deployed in or near a tissue, such as a skeletal muscle, of the patient. A pulse generator supplies one or more stimulations to the tissue, and a sensor, such as an accelerometer, detects the response of the tissue to the stimulations. A processor determines a concentration of ions in the extracellular fluid as a function of the response. The system may detect an ion imbalance based upon the determined concentration of ions.

Abstract: A medical device for sensing cardiac events that includes a plurality of light sources capable of emitting light at a plurality of wavelengths, and a detector to detect the emitted light. A processor determines a plurality of light measurements in response to the emitted light detected by the detector, updates, for each of the plurality of wavelengths, a first normalization coefficient and a second normalization coefficient in response to the detected emitted light, and adjusts the determined plurality of light measurements in response to the first normalization coefficient and the second normalization coefficient.

Abstract: A method and medical device for detecting signals that detects emitted light scattered by a volume of tissue delivered along a first pathway at a plurality of wavelengths to generate corresponding first detected light intensity output signals, detects emitted light scattered by the volume of tissue delivered along a second pathway different from the first pathway at a plurality of wavelengths to generate corresponding second detected light intensity output signals, determines whether a difference between the emitted light detected along the first pathway and the emitted light detected along the second pathway is greater than a predetermined threshold, and alters sensing by the device in response to the determining whether a difference is greater than the predetermined threshold.

Abstract: A method and medical device for detecting signals that detects emitted light scattered by a volume of tissue delivered along a first pathway and a second pathway different from the first pathway, detects emitted light scattered by a volume of tissue delivered along a third pathway and a fourth pathway different from the third pathway, determines a first uniformity corresponding to the emitted light detected along the first pathway and the second pathway, determines a second uniformity corresponding to the emitted light detected along third pathway and the fourth pathway, determines a total uniformity in response to the determined first uniformity and the determined second uniformity, and alters sensing by the device in response to the determined total uniformity.

Abstract: A method and medical device for detecting signals that detects emitted light scattered by a volume of tissue delivered along a first pathway at a plurality of wavelengths to generate corresponding first detected light intensity output signals, detects emitted light scattered by the volume of tissue delivered along a second pathway different from the first pathway at a plurality of wavelengths to generate corresponding second detected light intensity output signals, determines whether a difference between the emitted light detected along the first pathway and the emitted light detected along the second pathway is greater than a predetermined threshold, and alters sensing by the device in response to the determining whether a difference is greater than the predetermined threshold.

Abstract: A medical device system and associated method are used for monitoring a heart failure patient. A medical device for monitoring delivery of a therapy includes a sensor sensing an optical sensor signal corresponding to light attenuation by a volume of body tissue of a patient, a therapy delivery module to deliver a therapy, and a processor configured to compute a first tissue oxygenation measurement from the optical sensor signal prior to initiating delivery of the therapy, compute a second tissue oxygenation measurement from the optical sensor signal subsequent to initiating delivery of the therapy, compare the first and the second tissue oxygenation measurements, and determine whether the delivered therapy was successful in response to the first tissue oxygenation measurement and the second tissue oxygenation measurement.

Abstract: A medical system that includes an identification patch having a memory that stores identification information associated with the patch. A monitoring device to be used with the identification patch interrogates the patch to obtain the identification information stored within the memory of the patch. The monitoring device determines whether the identification information is valid and, if so, measures values representing one or more parameters of the patient. If the identification information is not valid, monitoring device does not measure values representing the one or more parameters of the patient.

Abstract: A medical device system and associated method control the delivery of a therapy to a patient. The system includes an activity sensor and detects a change in activity level of the patient. The system further include an optical sensor to sense signal corresponding to tissue light attenuation. The system computes a tissue oxygenation measurement in response to detecting a change in activity level. A parameter controlling delivery of the therapy is adjusted in response to detecting the decreased tissue oxygenation.

Abstract: An implantable sensor module includes a housing having an inner shell and an outer layer formed to extend over and enclose the inner shell to form an outer wall of the housing, the inner shell having a thickness extending between an inner wall of the inner shell and an outer wall of the inner shell, the outer layer having an inner side engaged against the outer wall of the inner shell and having a thickness extending between the inner side and the outer wall of the housing, wherein the inner shell and the outer layer form a substantially flat portion. A flexible diaphragm is formed within the inner shell and extends between a first edge and a second edge, and a shoulder extends adjacent to the first edge to extend the outer layer laterally away from a central medial line extending between the first and second edges of the diaphragm.

Abstract: An implantable sensor module and medical device includes a housing having an inner shell having a thickness extending between an inner wall and an outer wall and an outer layer, wherein the inner shell and the outer layer form a substantially flat portion. A shoulder extends adjacent to a diaphragm to extend the outer layer laterally away from a central medial line extending between edges of the diaphragm. A recess portion is formed between the diaphragm and an inner side of the outer layer, and an over-fill channel is formed by the outer layer extending through the outer layer from an opening formed at the outer wall to an opening formed along the inner side of the outer layer extending along the substantially flat portion.

Abstract: An implantable medical device having a flexible diaphragm is provided with a housing including a shell and an outer layer. The flexible diaphragm extends along the shell. The outer layer has an outer surface and an inner surface. An adhesive coating is applied between the diaphragm and the inner surface of the outer layer. The outer layer includes a recess along the diaphragm for receiving the adhesive.

Abstract: A first concentration of a chromophore corresponding to a measurement volume of an optical sensor is determined. A second concentration of the chromophore is obtained in the vicinity of the measurement volume corresponding to a change in at least one of a total concentration of the chromophore and a relative concentration of a first form of the chromophore to the total concentration of the chromophore in the measurement volume. Light remittance measurements including a first light wavelength and a second light wavelength are obtained corresponding to the first chromophore concentration and the second chromophore concentration. A coefficient for computing an index of a change in the chromophore concentration is computed using the difference between the first and second chromophore concentrations and the first and second light remittance measurements.

Abstract: A medical device for monitoring of oxygen saturation includes an optical sensor adapted for positioning adjacent to a tissue volume. The optical sensor has a light emitting portion capable of emitting light at a plurality of wavelengths and a light detecting portion capable of generating an electrical output signal corresponding to light incident on the detecting portion. A control module coupled to the optical sensor controls the light emitted by the light emitting portion. A monitoring module receives the output signal from the light detecting portion and computes a volume-independent measure of oxygen saturation in the volume of tissue using the output signal.

Abstract: An optical sensor for a medical device includes a fixed lens spacing between emit and receive modules to achieve target sensor sensitivity, while varying other sensor parameters in order to increase signal amplitude without increasing power demand. An optical sensor connected to a housing of a medical device includes a circuit board, an opto-electronic component, a wall, a lens, and a ferrule. The circuit board is arranged within the housing. The opto-electronic component is mounted on a surface of the circuit board. The wall protrudes from the surface of the circuit board and surrounds the opto-electronic component. The lens is offset from the surface of the circuit board. The ferrule is connected to the housing, the lens and the wall. An inner surface of the wall mates with an outer surface of the ferrule.

Abstract: An optical sensor for a medical device includes a fixed lens spacing between emit and receive modules to achieve target sensor sensitivity, while varying other sensor parameters in order to increase signal amplitude without increasing power demand. The arrangement of an opto-electronic component within an optical sensor receive module is improved by masking the receive module lens with an opaque member to create a masked lens leading edge that is aligned with a leading edge of the opto-electronic component.