Abstract: An electronic device comprises an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond a first bend of the ear canal. A distal temperature sensor is situated at a location of the enclosure that faces a tragus-side of the ear canal between the first and second bends when the enclosure is fully inserted into the ear canal. A proximal temperature sensor is situated on the enclosure at a location spaced apart from a surface of the ear canal and proximal of the distal temperature sensor in an outer ear direction when the enclosure is fully inserted into the ear canal. A processor, coupled to the distal and proximal temperature sensors and to memory, is configured to calculate an absolute core body temperature using a heat balance equation stored in the memory and the first and second temperature signals.

Abstract: An electronic device comprises an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond a first bend of the ear canal. A distal temperature sensor is situated at a location of the enclosure that faces a tragus-side of the ear canal between the first and second bends when the enclosure is fully inserted into the ear canal. A proximal temperature sensor is situated on the enclosure at a location spaced apart from a surface of the ear canal and proximal of the distal temperature sensor in an outer ear direction when the enclosure is fully inserted into the ear canal. A processor, coupled to the distal and proximal temperature sensors and to memory, is configured to calculate an absolute core body temperature using a heat balance equation stored in the memory and the first and second temperature signals.

Abstract: An electronic device comprises an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond a first bend of the ear canal. A distal temperature sensor is situated at a location of the enclosure that faces a tragus-side of the ear canal between the first and second bends when the enclosure is fully inserted into the ear canal. A proximal temperature sensor is situated on the enclosure at a location spaced apart from a surface of the ear canal and proximal of the distal temperature sensor in an outer ear direction when the enclosure is fully inserted into the ear canal. A processor, coupled to the distal and proximal temperature sensors and to memory, is configured to calculate an absolute core body temperature using a heat balance equation stored in the memory and the first and second temperature signals.

Abstract: An improved system for measuring changes in blood flow, particularly in the context of an automatic arrhythmia treatment device. The system includes a heater, exposable to a bloodstream, a driver providing power to the heater, a temperature sensor, isolated from the blood stream and thermally coupled to the temperature of the heater and a measurement circuit coupled to the temperature sensor, providing signals indicative of blood flow. The system may include an intravascular lead having a lead body wherein the heater is mounted to the lead body so as to dissipate its generated heat into the blood. The heater and temperature sensor may be thermally insulated from the lead body and the heater and the temperature sensor may be on substantially a single isotherm during operation.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines whether the sensed cardiac signals are associated with noise in response to the computed variation index, and confirms the determined cardiac event in response to the sensed cardiac signals not being associated with noise.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals, and a microprocessor computing a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determining whether deviations of the predetermined number of variation index samples over predetermined sampling windows are less than a deviation threshold, and determining, in response to the deviations being less than the deviation threshold, a corrected variation index trend in response to the changes in the variation index trend during the predetermined sampling windows.

Abstract: An implantable medical device and associated method monitor a heart failure patient by sensing a signal responsive to oxygen availability in an extravascular volume of skeletal muscle tissue. The signal is used to compute a tissue oxygenation measurement. A change in the tissue oxygenation measurement is detected, and a time interval corresponding to the detected change in muscle tissue oxygenation is computed. The time interval is used for detecting if a heart failure condition is worsening or improving.

Abstract: A medical device identifies a hemodynamically unstable arrhythmia based upon optical hemodynamic sensor signals. The optical hemodynamic sensor includes a light source for transmitting light corresponding to first and second wavelengths through a blood perfused tissue of a patient and a light detector for generating optical signals corresponding to an intensity of the detected light at the first and second wavelengths. At a low motion period for the patient, optical signals are obtained from the optical hemodynamic sensor and are analyzed to determine a baseline motion level for the patient. Subsequent signals obtained from the optical hemodynamic sensor are compared to the baseline motion levels, with only those signals corresponding to periods where motion does not exceed the baseline level of motion being further analyzed to determine if they are consistent with a hemodynamically unstable arrhythmia.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines a rate of change of the computed variation index trend, and confirms the determined cardiac event in response to the computed variation index trend and in response to the determined rate of change.

Abstract: An improved system for measuring changes in blood flow, particularly in the context of an automatic arrhythmia treatment device. The system includes a heater, exposable to a bloodstream, a driver providing power to the heater, a temperature sensor, isolated from the blood stream and thermally coupled to the temperature of the heater and a measurement circuit coupled to the temperature sensor, providing signals indicative of blood flow. The system may include an intravascular lead having a lead body wherein the heater is mounted to the lead body so as to dissipate its generated heat into the blood. The heater and temperature sensor may be thermally insulated from the lead body and the heater and the temperature sensor may be on substantially a single isotherm during operation.

Abstract: An improved method and apparatus for measuring changes in blood flow, particularly in the context of an automatic arrhythmia treatment device. The invention may employ a flow sensor which is activated in response to detection of a tachyarrhythmia or in response to delivery of an anti-tachyarrhythmia therapy. If activated in response to detection of tachyarrhythmia, the flow sensor may be employed to determine whether a substantial drop in cardiac output has or has not occurred, in order to select an appropriate therapy, in particular to avoid unnecessary delivery of high level shocks. If activated in response to delivery of an anti-tachyarrhythmia therapy, the flow sensor may be employed to determine whether the therapy was or was not successful in correcting a low cardiac output or whether a reduced cardiac output followed delivery of the therapy.

Abstract: An improved method and apparatus for measuring changes in blood flow, particularly in the context of an automatic arrhythmia treatment device. The invention may employ a flow sensor which is activated in response to detection of a tachyarrhythmia or in response to delivery of an anti-tachyarrhythmia therapy. If activated in response to detection of tachyarrhythmia, the flow sensor may be employed to determine whether a substantial drop in cardiac output has or has not occurred, in order to select an appropriate therapy, in particular to avoid unnecessary delivery of high level shocks. If activated in response to delivery of an anti-tachyarrhythmia therapy, the flow sensor may be employed to determine whether the therapy was or was not successful in correcting a low cardiac output or whether a reduced cardiac output followed delivery of the therapy.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines a rate of change of the computed variation index trend, and confirms the determined cardiac event in response to the computed variation index trend and in response to the determined rate of change.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals, and a microprocessor computing a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determining whether deviations of the predetermined number of variation index samples over predetermined sampling windows are less than a deviation threshold, and determining, in response to the deviations being less than the deviation threshold, a corrected variation index trend in response to the changes in the variation index trend during the predetermined sampling windows.

Abstract: A medical device identifies a hemodynamically unstable arrhythmia based upon optical hemodynamic sensor signals. The optical hemodynamic sensor includes a light source for transmitting light corresponding to first and second wavelengths through a blood perfused tissue of a patient and a light detector for generating optical signals corresponding to an intensity of the detected light at the first and second wavelengths. At a low motion period for the patient, optical signals are obtained from the optical hemodynamic sensor and are analyzed to determine a baseline motion level for the patient. Subsequent signals obtained from the optical hemodynamic sensor are compared to the baseline motion levels, with only those signals corresponding to periods where motion does not exceed the baseline level of motion being further analyzed to determine if they are consistent with a hemodynamically unstable arrhythmia.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines whether the sensed cardiac signals are associated with noise in response to the computed variation index, and confirms the determined cardiac event in response to the sensed cardiac signals not being associated with noise.