Perfusion trend indicator
First Claim
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1. A perfusion trend indicator comprising:
- 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;
a digital signal processor (DSP) within the patient monitor that inputs at least one of the plethysmograph channels and outputs a perfusion parameter accordingly;
a perfusion process that executes on the DSP so as to derive a perfusion trend from at least one of the plethysmograph channels, said perfusion trend different than historical values of said perfusion parameter, said perfusion trend responsive to trend values determined during relatively stable portions of said perfusion parameter, said trend values including at least a first baseline value during a first stable portion, a second value during a subsequent second stable portion, and a third value during a subsequent third stable portion, said perfusion trend responsive first to a first smoothed combination of said baseline and second values, and subsequently to a second smoothed combination of said second and third values, said stable portions including at least a plurality of values of said perfusion parameter; and
a patient monitor output that is responsive to the perfusion trend.
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Abstract
A perfusion trend indicator inputs a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site. Perfusion values are derived corresponding to the pulses. Time windows are defined corresponding to the perfusion values. Representative perfusion values are defined corresponding to the time windows. A perfusion trend is calculated according to differences between representative perfusion values of adjacent ones of the time windows.
720 Citations
12 Claims
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1. A perfusion trend indicator 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; a digital signal processor (DSP) within the patient monitor that inputs at least one of the plethysmograph channels and outputs a perfusion parameter accordingly; a perfusion process that executes on the DSP so as to derive a perfusion trend from at least one of the plethysmograph channels, said perfusion trend different than historical values of said perfusion parameter, said perfusion trend responsive to trend values determined during relatively stable portions of said perfusion parameter, said trend values including at least a first baseline value during a first stable portion, a second value during a subsequent second stable portion, and a third value during a subsequent third stable portion, said perfusion trend responsive first to a first smoothed combination of said baseline and second values, and subsequently to a second smoothed combination of said second and third values, said stable portions including at least a plurality of values of said perfusion parameter; and a patient monitor output that is responsive to the perfusion trend. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A perfusion trend indicator, comprising:
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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; and a digital signal processor (DSP) receiving as an input a plethysmograph responsive to said detected optical radiation, said DSP deriving perfusion index values responsive to said plethysmograph by generating perfusion index (PI) values from the plethysmograph according to predefined plethysmograph features and deriving a baseline PI value and PI trend values from the PI values relative to the baseline PI value, said PI trend values calculated by identifying stable data portions subsequent in time to the baseline PI value, smoothing said stable data portions and determining a difference between said smoothed stable data portions and said baseline PI; and outputting a value representative of said difference between said smoothed stable data portions and said baseline PI value. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification