Effects of head-down bed rest on complex heart rate variability: response to LBNP testing.
Effects of head-down bed rest on complex heart rate variability: response to LBNP testing.
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DOI：
10.1152/jappl.1994.77.6.2863
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发表时间：
1994-12
影响因子：
3.3
通讯作者：
Ary L. Goldberger;Joseph E. Mietus;David R. Rigney;M. L. Wood;S. Fortney
中科院分区：
文献类型：
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作者：
Ary L. Goldberger;Joseph E. Mietus;David R. Rigney;M. L. Wood;S. Fortney
头低位卧床休息用于模拟航天期间的生理变化。我们假设卧床休息会降低复杂的生理心率变异性的程度。我们分析了8名健康女性志愿者（年龄28-34岁）的数字化霍尔特记录的连续心率数据，这些志愿者接受了为期13天的6度头低位卧床研究和系列下体负压（LBNP）试验。心率变异性测量4分钟的数据集，使用传统的时域和频域的措施，以及与信号的“复杂性”（近似熵）的新措施。在卧床休息前（对照）、卧床休息期间（第4天和第9或11天）和卧床休息后2天（恢复期）获得数据。两个卧床日与卧床前相比，对LBNP的耐受性显著降低（P < 0.02）。在LBNP峰值时评估心率变异性。心率近似熵在第4、9、11天显著降低（P < 0.05），恢复期逐渐恢复正常。心率标准差和高功率频率与低功率频率的比值没有显著变化。我们的结论是，短期卧床休息与LBNP测试期间的心率复杂变异性降低健康的年轻成年女性。使用从非线性动力学（“混沌理论”）导出的方法测量心率复杂性可以提供生理变异性的这种损失的敏感标记，补充常规的时域和频域统计测量。
Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 degree head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal "complexity" (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly (P < 0.02) reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly (P < 0.05) decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ("chaos theory"), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.