Apparatus and method for determining a physiologic parameter of a patient applying fourier transformation
First Claim
1. Apparatus for determining at least one physiologic parameter of a patient, said apparatus comprising(a) at least one pressure sensor device adapted to provide readings of a blood pressure of said patient, and(b) storage means for storing said readings as at least one pressure curve over time,(c) fourier transformation means for subjecting said at least one pressure curve to a fourier transformation, and(d) an evaluator adapted to retrieve at least one power value selected from a group consisting ofa cardiac power value representing cardiac power anda respiratory power value representing respiratory power from at least one fourier transform received from said fourier transformation means and to determine said physiologic parameter from said at least one power value,wherein said evaluator is adapted to extract at least one power-spectrum selected from the group consisting ofa cardiac power-spectrum anda respiratory power-spectrum;
- from at least one fourier transform received from said fourier transform means to determine a width at a predetermined fraction of the maximum of a peak of said at least one power-spectrum and to use said width to separate harmonics.
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Abstract
The apparatus comprises a pressure sensor providing readings of a blood pressure of the patient and storage means for storing the readings as a pressure curve over time. Blood pressure is measured. The frequency difference between heart rate and breathing rate is used to separate the respiratory effect from the heart activity. In particular, the Fourier transform of the blood pressure and the spectral density are used to determine the contribution of each frequency. The respiratory and cardiac power spectra are determined. The ratio between both powers is calculated as the quotient of the integrals over the cardiac power spectrum and the respiratory power spectrum. A parameter usable to characterize volume responsiveness is determined using above ratio and a correction factor.
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Citations
21 Claims
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1. Apparatus for determining at least one physiologic parameter of a patient, said apparatus comprising
(a) at least one pressure sensor device adapted to provide readings of a blood pressure of said patient, and (b) storage means for storing said readings as at least one pressure curve over time, (c) fourier transformation means for subjecting said at least one pressure curve to a fourier transformation, and (d) an evaluator adapted to retrieve at least one power value selected from a group consisting of a cardiac power value representing cardiac power and a respiratory power value representing respiratory power from at least one fourier transform received from said fourier transformation means and to determine said physiologic parameter from said at least one power value, wherein said evaluator is adapted to extract at least one power-spectrum selected from the group consisting of a cardiac power-spectrum and a respiratory power-spectrum; from at least one fourier transform received from said fourier transform means to determine a width at a predetermined fraction of the maximum of a peak of said at least one power-spectrum and to use said width to separate harmonics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. Apparatus for determining at least one physiologic parameter of a patient, said apparatus comprising
(a) at least one pressure sensor device adapted to provide readings of a blood pressure of said patient, and (b) storage means for storing said readings as at least one pressure curve over time, (c) fourier transformation means for subjecting said at least one pressure curve to a fourier transformation, and (d) an evaluator adapted to retrieve at least one power value selected from a group consisting of a cardiac power value representing cardiac power and a respiratory power value representing respiratory power from at least one fourier transform received from said fourier transformation means and to determine said physiologic parameter from said at least one power value, wherein said at least one physiologic parameter of the patient includes a parameter indicative of volume-responsiveness.
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21. Apparatus for determining at least one physiologic parameter of a patient, said apparatus comprising
(a) at least one pressure sensor device adapted to provide readings of a blood pressure of said patient, and (b) storage means for storing said readings as at least one pressure curve over time, (c) fourier transformation means for subjecting said at least one pressure curve to a fourier transformation, and (d) an evaluator adapted to retrieve at least one power value selected from a group consisting of a cardiac power value representing cardiac power and a respiratory power value representing respiratory power from at least one fourier transform received from said fourier transformation means and to determine said physiologic parameter from said at least one power value, wherein said at least one physiologic parameter of said patient includes tidal volume, and wherein said evaluation means are adapted to determine tidal volume using said respiratory power-value.
Specification