Fractal fluctuations in human respiration
Fractal fluctuations in human respiration
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DOI：
10.1152/japplphysiol.00657.2004
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发表时间：
2004-12-01
影响因子：
3.3
通讯作者：
Gebber, GL
中科院分区：
文献类型：
--
作者：
Fadel, PJ;Barman, SM;Gebber, GL
本研究旨在描述清醒的健康成年人在休息条件下的呼吸波动。为此，我们用应变式气图记录了20名受试者的呼吸运动。然后，我们使用Allan因子、Fano因子和离散分析来检验呼吸次数、呼吸周期和呼吸幅度的波动是分形的（即时间尺度不变的）还是随机发生的。具体来说，我们测量了原始时间序列的Allan因子、Fano因子和色散分析曲线中幂律的斜率，并将其与替代曲线（随机数据集）的斜率进行了比较。此外，从Allan因子曲线的幂律斜率计算Hurst指数，确定呼吸次数波动之间的长期相关性是正相关还是负相关。结果可以总结如下。在9个受试者中，这三个参数的波动都是分形的。只有呼吸次数和呼吸幅度波动呈分形的受试者有4人，只有呼吸次数波动呈分形的受试者有3人，只有呼吸次数和呼吸周期波动呈分形的受试者有2人。其余两名受试者没有时间尺度不变的行为。结果表明，在大多数情况下，呼吸模式的明显随机波动实际上在一个以上的时间尺度上是相关的。呼吸次数、呼吸周期和呼吸幅度的分形波动受不同的过程控制。
The present study was designed to characterize respiratory fluctuations in awake, healthy adult humans under resting conditions. For this purpose, we recorded respiratory movements with a strain-gauge pneumograph in 20 subjects. We then used Allan factor, Fano factor, and dispersional analysis to test whether the fluctuations in the number of breaths, respiratory period, and breath amplitude were fractal (i.e., time-scale-invariant) or random in occurrence. Specifically, we measured the slopes of the power laws in the Allan factor, Fano factor, and dispersional analysis curves for original time series and compared these with the slopes of the curves for surrogates (randomized data sets). In addition, the Hurst exponent was calculated from the slope of the power law in the Allan factor curve to determine whether the long-range correlations among the fluctuations in breath number were positively or negatively correlated. The results can be summarized as follows. Fluctuations in all three parameters were fractal in nine subjects. There were four subjects in whom only the fluctuations in number of breaths and breath amplitude were fractal, three subjects in whom only the fluctuations in number of breaths were fractal, and two subjects in whom only fluctuations in breath number and respiratory period were fractal. Time-scale-invariant behavior was absent in the two remaining subjects. The results indicate that, in most cases, apparently random fluctuations in respiratory pattern are, in fact, correlated over more than one time scale. Moreover, the data suggest that fractal fluctuations in breath number, respiratory period, and breath amplitude are controlled by separate processes.