| 摘要 |
The invention provides a neck-worn sensor (referred to herein as the ‘necklace’) that is a single, body-worn system that measures the following parameters from an ambulatory patient: heart rate, pulse rate, pulse oximetry, respiratory rate, temperature, thoracic fluid levels, stroke volume, cardiac output, and a parameter sensitive to blood pressure called pulse transit time. From stroke volume, a first algorithm employing a linear model can estimate the patient's pulse pressure. And from pulse pressure and pulse transit time, a second algorithm, also employing a linear algorithm, can estimate systolic blood pressure and diastolic blood pressure. Thus, the necklace can measure all five vital signs along with hemodynamic parameters. It also includes a motion-detecting accelerometer, from which it can determine motion-related parameters such as posture, degree of motion, activity level, respiratory-induced heaving of the chest, and falls. |
| 主权项 |
1. A method for measuring pulse transit time (PTT) using a necklace system configured to be worn around a patient's neck, comprising:
measuring an analog ECG waveform with the necklace system, the analog ECG waveform measured with an ECG system housed in the necklace system and comprising an analog ECG circuit in electrical contact with at least two ECG electrodes; measuring an analog impedance waveform with the necklace system, the analog impedance waveform measured with an impedance system housed in the necklace system and comprising an analog impedance circuit in electrical contact with at least two impedance electrodes; measuring a motion signal with the necklace system, the motion signal measured with a motion sensor housed in the necklace system; digitizing the analog ECG and impedance waveforms with a digitizing system comprising an analog-to-digital converter and housed in the necklace system, the digitizing generating a digital ECG waveform and a digital impedance waveform; and, processing the digital ECG and impedance waveforms with a processing system comprising a microprocessor and housed in the necklace system when the motion signal or a processed version thereof is below a pre-determined threshold value, the processing configured to determine a first time point from the digital ECG waveform, a second time point from the digital impedance waveform, and a PTT from the difference between the first and second time points. |
