REAL-TIME MEASUREMENT OF VENTRICULAR STROKE VOLUME VARIATIONS BY CONTINUOUS ARTERIAL PULSE CONTOUR ANALYSIS
First Claim
1. A method for determining a cardiac or hemodynamic output value comprising:
- inputting a waveform data set corresponding to measurements of a measurement parameter;
generating a series of measurement values from the waveform data set;
computing an approximating function that best matches the measurement values according to a predetermined metric;
over each of at least one computation interval, creating a set of sampled, approximating values by sampling the approximating function at an interval-specific sampling rate;
low-pass filtering the sampled, approximating values; and
calculating an estimate of the output value as a function of the low-pass filtered, sampled approximating values.
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Abstract
Ventricular stroke volume variation (SVV) is estimated as a function of the standard deviation of arterial blood pressure value measured over each of at least two cardiac cycles, preferably over each of the cardiac cycles in a computation interval covering a full respiratory cycle. In one embodiment, maximum and minimum standard deviation values are determined over the computation interval. SVV is then estimated proportional to the ratio of the difference between the maximum and minimum standard deviation values and the mean of the standard deviation values. In another embodiment, SVV is then estimated proportional to the ratio of the standard deviation of the standard deviation values and the mean standard deviation over the entire computation interval. A pre-processing arrangement for improving reliability of estimates of more general cardiac or hemodynamic parameters is also disclosed and involves smoothing with an approximating function, and sampling and low-pass filtering at an adjustable rate.
81 Citations
11 Claims
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1. A method for determining a cardiac or hemodynamic output value comprising:
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inputting a waveform data set corresponding to measurements of a measurement parameter; generating a series of measurement values from the waveform data set; computing an approximating function that best matches the measurement values according to a predetermined metric; over each of at least one computation interval, creating a set of sampled, approximating values by sampling the approximating function at an interval-specific sampling rate; low-pass filtering the sampled, approximating values; and calculating an estimate of the output value as a function of the low-pass filtered, sampled approximating values. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for determining a cardiac or hemodynamic output value comprising:
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an arrangement for determining and inputting a waveform data set corresponding to measurements of a measurement parameter; a low-pass filter; a processing system including computer-executable code for generating a series of measurement values from the waveform data set; for computing an approximating function that best matches the measurement values according to a predetermined metric; over each of at least one computation interval, for creating a set of sampled, approximating values by sampling the approximating function at an interval-specific sampling rate; calculating an estimate of the output value as a function of the sampled approximating values after filtering by the low-pass filter. - View Dependent Claims (8, 9, 10, 11)
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Specification