Method and system for extracting cardiac parameters from plethysmographic signals
First Claim
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13. A system for extracting cardiac parameters from a plethysmographic signal, the plethysmographic signal being responsive to at least one cardiac parameter, the system comprising:
- (a) a first frequency-domain filter receiving the plethysmographic signal, having a dynamic lower cutoff frequency, and producing a first-filtered signal, (b) a second time-domain filter receiving the first filtered signal and producing a second filtered plethysmographic signal; and
(c) a processor for extracting the cardiac parameter from the second filtered signal.
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Abstract
A method and system for extracting cardiac parameters from a plethysmographic signal is described wherein the plethysmographic signal is passed through a first filter to remove non-cardiac components of the signal. A second filter averages a plurality of cardiac cycles and cardiac parameters are extracted from the averaged cardiac signal.
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Citations
29 Claims
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13. A system for extracting cardiac parameters from a plethysmographic signal, the plethysmographic signal being responsive to at least one cardiac parameter, the system comprising:
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(a) a first frequency-domain filter receiving the plethysmographic signal, having a dynamic lower cutoff frequency, and producing a first-filtered signal, (b) a second time-domain filter receiving the first filtered signal and producing a second filtered plethysmographic signal; and
(c) a processor for extracting the cardiac parameter from the second filtered signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22-1. The thoracocardiograph of claim 22 further comprising a plethysmographic inductive sensor for generating the first signal.
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24. A computer-readable medium comprising instructions for controlling a computer to generate a thoracocardiograph signal from a plethysmographic signal responsive to cardiac activity by:
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(a) frequency domain filtering the plethysmographic signal producing a first filtered signal; and
(b) time domain filtering the first filtered signal producing thoracocardiograph signal. - View Dependent Claims (25, 26)
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27. A method for extracting cardiac parameters from a plethysmographic signal characterized by a heart rate, the method comprising the steps of:
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(a) performing a first band-pass filtering operation on the plethysmographic signal producing a first filtered signal, the first filtering operation characterized by a lower corner frequency less than the heart rate;
(b) performing a second band-pass filtering operation on the plethysmographic signal producing a second filtered signal, the second filtering operation characterized by a lower corner frequency greater than the lower corner frequency of the first filtering operation;
(c) interpolating the first filtered signal and the second filtered signal based on the heart rate to produce a filtered plethysmographic signal; and
(d) extracting cardiac parameters from the filtered plethysmographic signal. - View Dependent Claims (28)
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29. A system for extracting cardiac parameters from a plethysmographic signal comprising:
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(a) means for receiving a heart rate;
(b) a first filter characterized by a first lower corner frequency, the first lower corner frequency not greater than the heart rate, the first filter capable of receiving the plethysmographic signal and generating a first filtered signal;
(c) a second filter characterized by a second lower corner frequency, the second lower corner frequency greater than the first lower corner frequency, the second filter capable of receiving the plethysmographic signal and generating a second filtered signal; and
(d) a processor for generating a filtered plethysmographic signal by interpolating the first filtered signal and the second filtered signal based on the heart rate and extracting a cardiac parameter from the filtered plethysmographic signal.
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Specification