Study on fetal heart rate variation using a probability distribution matrix

1.我们设计了一种新的方法，用概率分布矩阵来同时描述当前胎心率（FHR）和下一次胎心率之间的心跳差（DFHR）特征的变化，将FHR标绘在列中，DFHR标绘在行中，概率标绘在矩阵的相应元素中。本文应用脉冲多普勒自相关心电图对743例孕23-40周胎儿的胎心率进行了分析。随着妊娠的推进，FHR与DFHR出现了三种特定的概率分布模式。所提出的概率分布矩阵使人们能够将任何数量的FHR数据浓缩成一个统一的描述。这允许对数据进行整体分析，实现同等规模的定量组间比较。2.为了阐明随着妊娠的进展，控制胎儿心率变化的脑段，使用概率分布矩阵分析了12例无脑畸形胎儿和165例无并发症胎儿在25-32周妊娠期间的FHR数据。孕27-28周和29-30周是胎心率变化相关脑功能发育的关键时期。在早期，延髓对胎心率的变化起作用，而在晚期，延髓头侧的脑似乎也起着胎心率的调节作用.为了确定充分评估各种胎儿状况所需的FHR的最小数量，分析了从743例妊娠23至40周的正常胎儿中获得的9个连续两周间隔的概率分布矩阵。在妊娠23-40周时，用于评估胎儿的FHR的最小数量几乎相同，在9，000和10，000之间，具有67-75%的基线变异性（所谓的心跳间变异性）和25-33%的长期变异性，无论妊娠的进展如何。

1. We devised a new method using a probability distribution matrix to simultaneously describe variation in the characteristics of fetal heart rate (FHR) and beat-to beat difference (DFHR) between the present and the immediately following FHR.The FHRs were plotted in columns, DFHRs in rows and probabilities in the corresponding elements of the matrix. Analyzed were the age-related changes of FHR data obtained from 743 fetuses at 23-40 weeks' gestation using a pulsed Doppler cardiotocograph with autocorrelation. Three particular probability distribution patterns of FHR vs. DFHR emerged with advance in gestation. The probability distribution matrix presented enables one to condense any amount of FHR data, into one uniform description. This allows analysis of data, en bloc, achieving quantitative inter-group comparison, on an equivalent scale.2. To elucidate the brain segment which would control heart rate changes in human fetuses with advancing gestation, FHR data obtained from 12 anencephalic and 165 uncomplicated fetuses between 25-32 weeks' gestation were analyzed using a probability distribution matrix. There was a critical period between 27-28 and 29-30 weeks' gestation with regard to the developing brain function pertaining to FHR changes. In the early stage, the medulla oblongata plays a role in FHR changes, whereas, in the latter stage, the brain cephalad to the medulla also appears to take on the role of FHR regulator.3. To determine the minimum number of FHRs needed to assess various fetal conditions adequately, analyzed were 9 consecutive two-week interval probability distribution matrices obtained from 743 normal fetuses between 23 and 40 weeks' gestation. The minimum number of FHRs for assessment of the fetus at 23-40 weeks' gestation was almost the same, between 9,000 and 10,000, with 67-75% baseline variability (so called beat-to-beat variability) and 25-33% long-term variability regardless of advance in gestation.