Plethysmograph variability processor
First Claim
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1. A plethysmograph variability method comprising:
- inputting a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site;
deriving a plurality of perfusion values corresponding to the pulses, wherein deriving the plurality of perfusion values comprises;
identifying of the pulses and valleys of the pulses,calculating differential values for the pulses from the peaks of the pulses and the valleys of the pulses,determining reference values for the pulses, andnormalizing the differential values with the reference values;
determining a plurality of variability values indicative of the variability of a plurality of series of perfusion values, wherein each variability value is determined by calculating a difference between a first perfusion value of a series of perfusion values and a second perfusion value of the series of perfusion values and normalizing the difference with the first perfusion value;
calculating a plethysmograph variability parameter representative of the plurality of variability values; and
displaying the plethysmograph variability parameter.
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Abstract
A plethysmograph variability processor inputs a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site. The processor derives plethysmograph values based upon selected plethysmograph features, determines variability values, and calculates a plethysmograph variability parameter. The variability values indicate the variability of the plethysmograph features. The plethysmograph variability parameter is representative of the variability values and provides a useful indication of various physiological conditions and the efficacy of treatment for those conditions.
771 Citations
29 Claims
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1. A plethysmograph variability method comprising:
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inputting a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site; deriving a plurality of perfusion values corresponding to the pulses, wherein deriving the plurality of perfusion values comprises; identifying of the pulses and valleys of the pulses, calculating differential values for the pulses from the peaks of the pulses and the valleys of the pulses, determining reference values for the pulses, and normalizing the differential values with the reference values; determining a plurality of variability values indicative of the variability of a plurality of series of perfusion values, wherein each variability value is determined by calculating a difference between a first perfusion value of a series of perfusion values and a second perfusion value of the series of perfusion values and normalizing the difference with the first perfusion value; calculating a plethysmograph variability parameter representative of the plurality of variability values; and displaying the plethysmograph variability parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A plethysmograph variability processing system comprising:
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an optical sensor that transmits multiple wavelengths of optical radiation into a tissue site, detects the optical radiation after attenuation by pulsatile blood flowing within the tissue site, and generates a sensor signal responsive to the detected optical radiation; a patient monitor that demodulates the sensor signal so as to generate a plurality of plethysmograph channels; and a digital signal processor (DSP) within the patient monitor configured to; receive at least one plethysmograph channel of the plurality of plethysmograph channels, determine a plurality of plethysmograph values from the at least one plethysmograph channel, wherein the plethysmograph values comprise perfusion values that are calculated by normalizing differences between peaks of the at least one plethysmograph channel and valleys of the at least one plethysmograph channel with reference values, calculate a plurality of variability values based on the plurality of plethysmograph values, wherein each variability value is calculated by normalizing a difference between a first perfusion value and a second perfusion value with the first perfusion value, calculate a plethysmograph variability (PV) parameter based on the plurality of variability values, generate a patient monitor output that is responsive to the PV parameter. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A plethysmograph variability method comprising:
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inputting at least one plethysmograph channel of a plurality of plethysmograph channels; calculating a plurality of plethysmograph values from the at least one plethysmograph channel by normalizing differences between peaks of the at least one plethysmograph channel and valleys of the at least one plethysmograph channel with reference values; defining a plurality of windows each encompassing a unique time interval of the plethysmograph values; calculating a plurality of variability values, each of the variability values derived by normalizing a difference between a first plethysmograph value in a first window and a second plethysmograph value in the first window with the first plethysmograph value; defining a second plurality of windows each encompassing a unique time interval of the variability values; calculating a plurality of parameter values, each of the parameter values derived from the variability values encompassed in a unique one of the second windows; and outputting the parameter values. - View Dependent Claims (22)
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23. A plethysmograph variability processing system having a sensor that transmits multiple wavelengths of optical radiation into a tissue site and that detects the optical radiation after attenuation by pulsatile blood flow within a tissue site so as to provide a plethysmograph input to a digital signal processor (DSP), the input selected from a plurality of channels corresponding to the multiple wavelengths, the DSP executes instructions for deriving plethysmograph variability from the plethysmograph, comprising:
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a plethysmograph input; means for generating plethysmograph values from the plethysmograph input by normalizing differences between peaks of the plethysmograph input and valleys of the plethysmograph input with reference values; means for deriving variability values from the plethysmograph values, wherein each variability value is determined by calculating a difference between a first plethysmograph value and a second plethysmograph value and normalizing the difference with the first plethysmograph value; and means for deriving a plethysmograph variability (PV) parameter from the plethysmograph values. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification