APPARATUS AND METHOD FOR MONITORING PRESSURE RELATED CHANGES IN THE EXTRA-THORACIC ARTERIAL CIRCULATORY SYSTEM
First Claim
1. A non-invasive cardiac monitoring system comprising:
- a photoemitter adapted to transmit light through a portion of a patient'"'"'s extra-thoracic arterial circulation;
a photodetector adapted to receive light after having been transmitted through such a patient and for outputting a first signal based on the received light;
processing means for producing a cardiac pressure signal as a measure of such a patient'"'"'s cardiac function by isolating cardiac related pressure variations in the first signal.
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Accused Products
Abstract
A method and apparatus for monitoring changes in the intra-thoracic pressure of a patient due to the patient'"'"'s respiratory activity or volumetric changes in the extra-thoracic arterial circulatory system due to cardiac function based on the changes in pressure in the patient'"'"'s extra-thoracic arterial circulatory system as measured by a plethysmography sensor, such as an photoplethysmograph. A frequency spectrum is generated for the plethysmograph signal and the frequencies of interest is isolated from the frequency spectrum by setting appropriate cutoff frequencies for the frequency spectrum. This isolated frequency is used to filter the plethysmograph signal to provide a signal indicative of the patient'"'"'s respiratory activity or cardiac function.
123 Citations
34 Claims
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1. A non-invasive cardiac monitoring system comprising:
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a photoemitter adapted to transmit light through a portion of a patient'"'"'s extra-thoracic arterial circulation; a photodetector adapted to receive light after having been transmitted through such a patient and for outputting a first signal based on the received light; processing means for producing a cardiac pressure signal as a measure of such a patient'"'"'s cardiac function by isolating cardiac related pressure variations in the first signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A non-invasive cardiac monitoring method comprising:
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passing light through a portion of a patient'"'"'s extra-thoracic arterial circulation; receiving light after having been passed through such a patient; outputting a first signal based on the received light; and producing a cardiac pressure signal as a measure of such a patient'"'"'s cardiac function by isolating cardiac related pressure variations in the first signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A cardio-pulmonary monitoring system comprising:
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(a) sensing means for detecting a physiological characteristic of a patient associated with pressure changes in such a patient'"'"'s extra-thoracic arterial circulation and for outputting a first signal indicative of such pressure changes; (b) processing means for producing a cardiac pressure signal as a measure of such a patient'"'"'s cardiac function by isolating cardiac related pressure variations in the first signal, wherein the processing means comprises; (1) frequency analyzing means for determining frequency components of the first signal, (2) heart rate frequency component identifying means for identifying a heart rate frequency component (fHR) from the frequency components of the first signal, and (3) dynamic filtering means for filtering the first signal based on the heart rate frequency component fHR so as to isolate the heart rate frequency component fHR from the first signal to produce the cardiac pressure signal. - View Dependent Claims (28, 29, 30, 31)
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32. A cardio-pulmonary monitoring system comprising:
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(a) sensing means for detecting a physiological characteristic of a patient associated with pressure changes in such a patient'"'"'s extra-thoracic arterial circulation and for outputting a first signal indicative of such pressure changes; (b) processing means for producing a cardiac pressure signal as a measure of such a patient'"'"'s cardiac function by isolating cardiac related pressure variations in the first signal, wherein the processing means comprises; (1) frequency analyzing means for determining frequency components of the first signal, (2) respiratory rate frequency component identifying means for identifying a respiratory rate frequency component fRR from the frequency components of the first signal, and (3) dynamic filtering means for filtering the physiologic signal based on the respiratory rate frequency component fRR so as to remove the respiratory rate frequency component fRR from the physiologic signal, thereby isolating a heart rate frequency component fHR of the first signal to produce the cardiac pressure signal. - View Dependent Claims (33, 34)
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Specification