Quantification of fetal heart rate variation using a probability distribution matrix.
Analysis of FHR variability attempts to be able to distinguish which FHR changes are physiological and which are pathological. From the results of such studies, it is hoped that clinicians will be provided with the means to identify accurately which fetuses are healthy, which are at risk and which are actually in distress at any gestational age. The probability distribution matrix presented has the outstanding advantage of enabling one to condense any amount of FHR data into one uniform description for analysis en bloc. Not even one FHR is sacrificed; each one contributes to the FHR vs. DFHR distribution pattern. Where the probability distribution matrix is made from many FHR samples taken from healthy fetuses under natural day-to-day maternal circumferences, as we have done, this matrix can be considered as a physiologically unbiased reference. The subtraction matrix is characterized by the difference in FHR vs. DFHR distribution patterns between two probability distribution matrices compared, representing the equal residue of net absolute value. The larger the difference in FHR vs. DFHR distribution between two probability distribution matrices, the larger these kinds of residue values, and if two probability distribution matrices are identical, all the elements in the subtraction matrix indicate the residue values of zero. Our probability distribution matrix approach confirms the results of previously reported studies which utilized other analytical strategies. Therefore, we can evaluate quantitatively age-related FHR changes used as variables, such as the subtraction matrix and difference rate. By varying intervals between paired FHRs (e.g. selecting the original FHR--skip--select the following FHR--skip 2 FHR--select the next FHR, etc.), the probability distribution matrix could be adopted as a general tool for analysis of sequential changes in large numbers of FHR for further studies.
Koyanagi
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T
Maternity and Perinatal Care Unit, Kyushu University Hospital, Fukuoka, Japan.
Yoshizato
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T
Nakano
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H
D015982:Bias; D015148:Cardiotocography; D005260:Female; D005316:Fetal Distress / Q000175:diagnosis* / Q000453:epidemiology; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D015233:Models, Statistical; D010865:Pilot Projects; D011247:Pregnancy; D011336:Probability; D012815:Signal Processing, Computer-Assisted; D018617:Ultrasonography, Doppler, Pulsed; D016216:Ultrasonography, Prenatal