Stereo pulse oximeter
First Claim
1. A method of non-invasively measuring a constituent of blood flowing within body tissue, the method comprising the steps of:
- receiving at least first and second intensity signals from a light-sensitive detector that detects light of at least first and second wavelengths attenuated by body tissue carrying blood;
determining at least one of a set of fundamental and associated harmonic frequencies corresponding to an induced ventilator frequency; and
calculating a blood constituent according to first and second magnitudes of said first and second intensity signals corresponding to said at least one of said set of fundamental and associated harmonic frequencies.
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Accused Products
Abstract
An improved pulse oximeter provides for simultaneous, noninvasive oxygen status and photoplethysmograph measurements at both single and multiple sites. In particular, this multiple-site, multiple-parameter pulse oximeter, or “stereo pulse oximeter” simultaneously measures both arterial and venous oxygen saturation at any specific site and generates a corresponding plethysmograph waveform. A corresponding computation of arterial minus venous oxygen saturation is particularly advantageous for oxygen therapy management. An active pulse-inducing mechanism having a scattering-limited drive generates a consistent pulsatile venous signal utilized for the venous blood measurements. The stereo pulse oximeter also measures arterial oxygen saturation and plethysmograph shape parameters across multiple sites. A corresponding calculation of delta arterial saturation and comparison of plethysmograph shape parameters between multiple sites is particularly advantageous for the detection and management of persistent pulmonary hypertension in neonates (PPHN), a patent ductus arteriosis (PDA), and aortic coarctation.
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Citations
18 Claims
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1. A method of non-invasively measuring a constituent of blood flowing within body tissue, the method comprising the steps of:
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receiving at least first and second intensity signals from a light-sensitive detector that detects light of at least first and second wavelengths attenuated by body tissue carrying blood;
determining at least one of a set of fundamental and associated harmonic frequencies corresponding to an induced ventilator frequency; and
calculating a blood constituent according to first and second magnitudes of said first and second intensity signals corresponding to said at least one of said set of fundamental and associated harmonic frequencies. - View Dependent Claims (2, 3, 4, 5)
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6. A method of non-invasively monitoring venous blood oxygen saturation comprising the steps of:
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transmitting optical radiation through a fleshy medium having ventilator-induced pulsing blood flowing therein, the optical radiation selected so as to be attenuated by said blood;
detecting said optical radiation after attenuation through the fleshy medium;
outputting an output signal indicative of optical characteristics of the fleshy medium; and
determining venous blood oxygen saturation based upon said output signal, wherein said determining includes processing said output signal to extract ventilation-induced variations therefrom. - View Dependent Claims (7, 8, 9, 10)
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- 11. In a signal processor for processing first and second intensity signals from a light-sensitive detector that detects light of at least first and second wavelengths attenuated by body tissue carrying pulsing blood at least partially induced by a ventilator operating at a ventilator frequency, a method comprising measuring a blood constituent according to ventilator frequency related components of first and second intensity signals from a light sensitive detector that detects light attenuated by body tissue carrying pulsing blood at least partially induced by a ventilator operating at a ventilator frequency.
Specification