Patent Document ID: 10092200
Application ID: 13858249
Patent Status: 1

Claim One:
1. A computerized method of determining plethysmograph variability in a non-invasive electronic patient monitor using a signal processor comprising: converting digital control signals into analog drive signals; causing a sensor emitter to emit a plurality of wavelengths of light by communicating the analog drive signals to the sensor emitter; receiving a sensor signal from a sensor detector in response to attenuation by pulsatile blood flow within a tissue site; demodulating the sensor signal to generate a plethysmograph waveform having pulses corresponding to the pulsatile blood flow within the tissue site; determining a plurality of perfusion values corresponding to the pulses, wherein said determining the plurality of perfusion values comprises: identifying peaks and valleys of the pulses, and calculating differential values for the pulses from the peaks and the valleys of the pulses, wherein the differential values comprise a difference between the peaks and the valleys of the pulses; storing a first series of perfusion values of the plurality of perfusion values in a first buffer; sorting the first series of perfusion values within the first buffer from a largest perfusion value to a smallest perfusion value; removing at least two perfusion values from the first series of perfusion values to form a modified first series of perfusion values, wherein at least one perfusion value is removed from a set of largest perfusion values of the first series of perfusion values, and at least one perfusion value is removed from a set of smallest perfusion values of the first series of perfusion values; determining a first variability value indicative of variability of the modified first series of perfusion values based on a difference between a first perfusion value of the modified first series of perfusion values and a second perfusion value of the modified first series of perfusion values and a normalization of the difference with the first perfusion value of the modified first series of perfusion values; storing a second series of perfusion values of the plurality of perfusion values in a second buffer; sorting the second series of perfusion values within the second buffer from a largest perfusion value to a smallest perfusion value; removing at least one perfusion value from a set of largest perfusion values of the second series of perfusion values and at least one perfusion value from a set of smallest perfusion values of the second series of perfusion values to form a modified second series of perfusion values; determining a second variability value indicative of variability of the modified second series of perfusion values based on a difference between a first perfusion value of the modified second series of perfusion values and a second perfusion value of the modified second series of perfusion values and a normalization of the difference with the first perfusion value of the modified second series of perfusion values; determining a plethysmograph variability parameter representative of at least the first variability value and the second variability value; and causing a display device to display the plethysmograph variability parameter.