Neck-worn physiological monitor

A sensor for simultaneously measuring from a patient an index correlating to fluid content in the thoracic cavity (TFI), the sensor comprising:

• a sensing portion having a flexible housing;
• an elongated securement member extending from the sensing portion and configured to position the sensing portion in a consistent location on the patient's body for measurements made by the sensor,
• at least one pair of electrode contact points disposed within the housing, with each pair of electrode contact points comprising a current-injecting electrode contact point and a voltage-sensing electrode contact point;
• an analog impedance circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the impedance circuit being configured to generate an analog impedance waveform based on sensed voltage;
• a digital processing system disposed within the housing and comprising a microprocessor and an analog-to-digital converter, the digital processing system being configured to digitize the analog impedance waveform to generate a digital impedance waveform;
• and
• a thoracic fluid-measuring system disposed within the housing and configured to operate a third algorithm, which third algorithm processes the digital impedance waveform to determine a value of TFI.

A sensor for simultaneously measuring from a patient systolic blood pressure (SYS), stroke volume (SV), and an index correlating to fluid content in the thoracic cavity (TFI), the sensor comprising:

• a sensing portion having a flexible housing;
• an elongated securement member extending from the sensing portion and configured to position the sensing portion in a consistent location on the patient's body for measurements made by the sensor,
• at least one pair of electrode contact points disposed within the housing, with each pair of electrode contact points comprising a current-injecting electrode contact point and a voltage-sensing electrode contact point;
• an analog ECG circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the ECG circuit configured to generate an analog ECG waveform based on sensed voltage;
• an analog impedance circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the impedance circuit being configured to generate an analog impedance waveform based on sensed voltage;
• a digital processing system disposed within the housing and comprising a microprocessor and an analog-to-digital converter, the digital processing system being configured to:
• 1) digitize the analog ECG waveform to generate a digital ECG waveform, and 2) digitize the analog impedance waveform to generate a digital impedance waveform;
• a blood pressure-monitoring system disposed within the housing and configured to operate a first algorithm, which first algorithm collectively processes the digital impedance and digital ECG waveforms to determine a value of SYS;
• a SV-monitoring system disposed within the housing and configured to operate a second algorithm, which second algorithm processes the digital impedance waveform to determine a value of SV;
• and
• a thoracic fluid-measuring system disposed within the housing and configured to operate a third algorithm, which third algorithm processes the digital impedance waveform to determine a value of TFI.

A sensor for measuring trends in systolic blood pressure (SYS), stroke volume (SV), and an index correlating to fluid content in the thoracic cavity (TFI), the sensor comprising:

• a sensing portion having a flexible housing;
• an elongated securement member extending from the sensing portion and configured to position the sensing portion in a consistent location on the patient's body for each of multiple measurements made at different times by the sensing portion,
• at least one pair of electrode contact points disposed within the housing, with each pair of electrode contact points comprising a current-injecting electrode contact point and a voltage-sensing electrode contact point;
• an analog ECG circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the ECG circuit configured to generate an analog ECG waveform based on sensed voltage;
• an analog impedance circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the impedance circuit being configured to generate an analog impedance waveform based on sensed voltage;
• a digital processing system disposed within the housing and comprising a microprocessor and an analog-to-digital converter, the digital processing system being configured to:
• 1) digitize the analog ECG waveform to generate a digital ECG waveform, and 2) digitize the analog impedance waveform to generate a digital impedance waveform;
• a blood pressure-monitoring system disposed within the housing and configured to operate a first algorithm, which first algorithm collectively processes the digital impedance and digital ECG waveforms to determine a value of SYS;
• a SV-monitoring system disposed within the housing and configured to operate a second algorithm, which second algorithm processes the digital impedance waveform to determine a value of SV;
• a thoracic fluid-measuring system disposed within the housing and configured to operate a third algorithm, which third algorithm processes the digital impedance waveform to determine a value of TFI;
• and
• a system for calculating trends in SYS, SV, and TFI by analyzing values of SYS, SV, and TFI from measurements made at different times by the sensing portion, wherein the sensing portion is positioned on the patient's body for each measurement in substantially the same location by the elongated securement member.

A sensor for generating alerts indicating an onset of heart failure by measuring trends in systolic blood pressure (SYS), stroke volume (SV), and an index correlating to fluid content in the thoracic cavity (TFI), the sensor comprising:

• a sensing portion having a flexible housing;
• an elongated securement member extending from the sensing portion and configured to position the sensing portion in a consistent location on the patient's body for each of multiple measurements made at different times by the sensing portion,
• at least one pair of electrode contact points disposed within the housing, with each pair of electrode contact points comprising a current-injecting electrode contact point and a voltage-sensing electrode contact point;
• an analog ECG circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the ECG circuit configured to generate an analog ECG waveform based on sensed voltage;
• an analog impedance circuit disposed within the housing and in electrical contact with said at least one pair of electrode contact points, the impedance circuit being configured to generate an analog impedance waveform based on sensed voltage;
• a digital processing system disposed within the housing and comprising a microprocessor and an analog-to-digital converter, the digital processing system being configured to:
• 1) digitize the analog ECG waveform to generate a digital ECG waveform, and 2) digitize the analog impedance waveform to generate a digital impedance waveform;
• a blood pressure-monitoring system disposed within the housing and configured to operate a first algorithm, which first algorithm collectively processes the digital impedance and digital ECG waveforms to determine a value of SYS;
• a SV-monitoring system disposed within the housing and configured to operate a second algorithm, which second algorithm processes the digital impedance waveform to determine a value of SV;
• a thoracic fluid-measuring system disposed within the housing and configured to operate a third algorithm, which third algorithm processes the digital impedance waveform to determine a value of TFI;
• a system for calculating trends in SYS, SV, and TFI by analyzing values of SYS, SV, and TFI measured at different times by the sensing portion, wherein the sensing portion is positioned on the patient's body for each measurement in roughly the same location by the elongated securement member;
• and
• a system for generating an alert indicating the onset of heart failure when TFI trends to a lower value, SV trends to a lower value, and SYS trends to a lower value.

A system for measuring physiological signals from a patient, comprising:

• a flexible housing configured to be worn around a patient's neck and conform to their chest, the flexible housing comprising a first component enclosing a first circuit board, a second component enclosing a second circuit board, a third component enclosing a third circuit board, a fourth component enclosing a first electrical conductor, and a fifth component enclosing a second electrical conductor:
• wherein at least one of the first, second, and third circuit boards comprises an analog circuit configured to measure at least one time-dependent analog waveform from the patient;
• wherein at least one of the first, second, and third circuit boards comprises a digital processing system comprising a microprocessor and an analog-to-digital converter configured to digitize the at least one time-dependent analog waveform to generate a time-dependent digital waveform;
• and
• wherein at least one of the first, second, an third circuit boards comprises at least one sensor for monitoring the physiological signal from the patient, the sensor configured to operate a first algorithm to process the time-dependent digital waveform to determine the physiological signal.