SYSTEMS AND METHODS FOR HIGH-PASS FILTERING A PHOTOPLETHYSMOGRAPH SIGNAL
First Claim
1. A system for high-pass filtering a photoplethysmograph (PPG) signal used for determining blood pressure value of a subject comprising:
- a sensor configured to generate the PPG signal; and
a pulse oximeter configured to;
receive the PPG signal from the sensor;
determine a pulse frequency value indicative of a pulse rate of the subject;
compute a cut-off frequency for a high-pass filter based at least in part on the pulse frequency value, such that the cut-off frequency is approximately equal to the sum of the pulse frequency value and a selected frequency value, wherein the selected frequency value is one of;
0.5 Hz, 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 10 Hz, and 15 Hz;
generate a filtered PPG signal by applying the high-pass filter to the PPG signal; and
determine, based at least in part on the filtered PPG signal, the blood pressure value of the subject.
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Accused Products
Abstract
According to embodiments, systems and methods for high-pass filtering a plethysmograph or photoplethysmograph (PPG) signal are disclosed. A sensor or probe may be used to obtain a plethysmograph or PPG signal from a subject. The sensor may be placed at any suitable location on the body, e.g., the forehead, finger, or toe. The PPG signal generated by the sensor may be high-pass filtered to disambiguate certain features of the PPG signal, including one or more characteristic points. The cut-off frequency for the high-pass filter may be greater than 0.75 Hz and less than 15 Hz. The cut-off frequency for the high-pass filter may be selected to be greater than the subject'"'"'s computed pulse rate. These characteristic points on the filtered PPG signal may be used to compute non-invasive blood pressure measurements continuously or on a periodic basis. For example, the time difference between two or more characteristic points in a high-pass filtered version of the generated PPG signal may be computed. The time difference may be used to compute non-invasive blood pressure measurements continuously or on a periodic basis.
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20 Claims
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1. A system for high-pass filtering a photoplethysmograph (PPG) signal used for determining blood pressure value of a subject comprising:
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a sensor configured to generate the PPG signal; and a pulse oximeter configured to; receive the PPG signal from the sensor; determine a pulse frequency value indicative of a pulse rate of the subject; compute a cut-off frequency for a high-pass filter based at least in part on the pulse frequency value, such that the cut-off frequency is approximately equal to the sum of the pulse frequency value and a selected frequency value, wherein the selected frequency value is one of;
0.5 Hz, 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 10 Hz, and 15 Hz;generate a filtered PPG signal by applying the high-pass filter to the PPG signal; and determine, based at least in part on the filtered PPG signal, the blood pressure value of the subject. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for high-pass filtering a photoplethysmograph (PPG) signal used for determining a blood pressure value of a subject comprising:
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generating, using a sensor, the PPG signal; determining, using a pulse oximeter, a pulse frequency value indicative of a pulse rate of the subject; computing, using the pulse oximeter, a cut-off frequency for a high-pass filter based at least in part on the pulse frequency value, such that the cut-off frequency is approximately equal to the sum of the received pulse frequency value and a selected frequency value, wherein the selected frequency value is one of;
0.5 Hz, 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 10 Hz, and 15 Hz;generating, using the pulse oximeter, a filtered PPG signal by applying the high-pass filter to the PPG signal; and determining, using the pulse oximeter, based at least in part on the filtered PPG signal, the blood pressure value of the subject. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification