Departamento de Fisioterapia, Universidade Federal de São Carlos, SP, Brasil.
Braz J Med Biol Res. 2011 Jan;44(1):29-37. doi: 10.1590/s0100-879x2010007500137. Epub 2010 Dec 3.
The objective of this study was to use linear and non-linear methods to investigate cardiac autonomic modulation in healthy elderly men and women in response to a postural change from the supine to the standing position. Fourteen men (66.1 ± 3.5 years) and 10 women (65.3 ± 3.3 years) were evaluated. Beat-to-beat heart rate was recorded in the supine and standing positions. Heart rate variability was studied by spectral analysis, including both low (LFnu-cardiac sympathetic modulation (CSM) indicator) and high (HFnu-cardiac vagal modulation (CVM) indicator) frequencies in normalized units as well as the low frequency/high frequency (LF/HF) ratio. Symbolic analysis was performed using the following indexes: 0V% (CSM indicator), 1V% (CSM and CVM indicators), 2LV% (predominantly CVM indicator) and 2ULV% (CVM indicator). Shannon entropy was also calculated. Men presented higher LFnu and LF/HF ratio and lower HFnu and 1V% symbolic index (57.56, 4.14, 40.53, 45.96, respectively) than women (24.60, 0.45, 72.47, 52.69, respectively) in the supine position. Shannon entropy was higher among men (3.53) than among women (3.33) in the standing position, and also increased according to postural change in men (3.25; 3.53). During postural change, the LFnu (24.60; 49.85) and LF/HF ratio (0.45; 1.72) increased, with a concomitant decrease in HFnu (72.47; 47.56) and 2LV% (14.10; 6.95) in women. Women presented increased CSM in response to postural change and had higher CVM and lower CSM than men in the supine position. In conclusion, women in the age range studied presented a more appropriate response to a postural change than men, suggesting that cardiac autonomic modulation may be better preserved in women than in men.
本研究旨在采用线性和非线性方法，探究健康老年男性和女性在由仰卧位变为站立位时的心脏自主神经调节情况。14 名男性（66.1 ± 3.5 岁）和 10 名女性（65.3 ± 3.3 岁）参与了评估。在仰卧位和站立位记录心率的逐拍变化。通过频谱分析研究心率变异性，包括正常单位下的低频（LFnu-心脏交感神经调制（CSM）指标）和高频（HFnu-心脏迷走神经调制（CVM）指标）以及低频/高频（LF/HF）比值。还进行了符号分析，采用的指标有 0V%（CSM 指标）、1V%（CSM 和 CVM 指标）、2LV%（主要为 CVM 指标）和 2ULV%（CVM 指标）。同时计算了香农熵。男性在仰卧位时的 LFnu 和 LF/HF 比值高于女性（分别为 57.56、4.14、40.53、45.96 和 24.60、0.45、72.47、52.69），HFnu 和 1V%符号指数则低于女性（分别为 40.53、45.96 和 24.60、0.45）。男性在站立位时的香农熵高于女性（分别为 3.53 和 3.33），而且男性的香农熵在体位改变时增加（分别为 3.25、3.53）。在体位改变过程中，女性的 LFnu（24.60、49.85）和 LF/HF 比值（0.45、1.72）增加，HFnu（72.47、47.56）和 2LV%（14.10、6.95）降低。女性对体位改变的 CSM 反应增加，且在仰卧位时的 CVM 高于男性，CSM 低于男性。总之，研究中年龄范围的女性对体位改变的反应比男性更合适，这表明女性的心脏自主神经调节可能比男性保存得更好。
