MONITORING DEVICE AND METHOD FOR ESTIMATING BLOOD CONSTITUENT CONCENTRATION FOR TISSUES WITH LOW PERFUSION
First Claim
1. Method for estimating blood constituent concentration of a user under low perfusion conditions using a spectrophotometry-based monitoring device comprising a multichannel sensor formed from a plurality of channels, and a cardiovascular sensor;
- comprising;
measuring a plurality of photoplethysmographic (PPG) signals, each PPG signal being measured by one of the channels;
measuring a cardio-synchronous(CV) signal by using the cardiovascular sensor;
detecting an instantaneous heart rate and determining a heart rate variability from the CV signal;
for each detected heart rate, projecting the measured PPG signals multiplied by a window function on a principal frequency component, and selecting reliable projected PPG signals; and
estimating a value of said blood constituent concentration from the magnitude of said reliable projected PPG signals selected over a predetermined time period;
said window function having a window length which is adjusted at each detected heart rate according to the determined heart rate variability; and
the frequency of said principal frequency component being estimated by averaging the heart rate over the window length.
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Abstract
The present disclosure relates to a method for estimating blood constituent concentration of a user under low perfusion conditions using a spectrophotometry-based monitoring device; the method comprising: measuring a plurality of photoplethysmographic (PPG) signals; measuring a cardio-synchronous (CV) signal; detecting an instantaneous heart rate and determining a heart rate variability from the CV signal; selecting reliable projected PPG signals; estimating a value of said blood constituent concentration from the magnitude of said reliable projected PPG signals. The disclosed method requires diminished computational load compared to conventional methods based on frequency domain approach as FFT or DCT. The disclosure also pertains to a monitoring device for estimating blood constituent concentration in tissue under low perfusion of a user.
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Citations
18 Claims
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1. Method for estimating blood constituent concentration of a user under low perfusion conditions using a spectrophotometry-based monitoring device comprising a multichannel sensor formed from a plurality of channels, and a cardiovascular sensor;
- comprising;
measuring a plurality of photoplethysmographic (PPG) signals, each PPG signal being measured by one of the channels; measuring a cardio-synchronous(CV) signal by using the cardiovascular sensor; detecting an instantaneous heart rate and determining a heart rate variability from the CV signal; for each detected heart rate, projecting the measured PPG signals multiplied by a window function on a principal frequency component, and selecting reliable projected PPG signals; and estimating a value of said blood constituent concentration from the magnitude of said reliable projected PPG signals selected over a predetermined time period; said window function having a window length which is adjusted at each detected heart rate according to the determined heart rate variability; and the frequency of said principal frequency component being estimated by averaging the heart rate over the window length. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- comprising;
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14. Monitoring device for estimating blood constituent concentration in tissue under low perfusion of a user comprising a multichannel sensor formed from a plurality of channels for delivering photoplethysmographic (PPG) signals;
and a cardiovascular sensor for delivering a cardio-synchronous (CV) signal. - View Dependent Claims (15, 16, 17, 18)
Specification