Youde J, Panerai R B, Gillies C, Potter J F
University Division of Medicine for the Elderly, The Glenfield Hospital, Groby Road, Leicester LE3 9QP, England.
Clin Auton Res. 2002 Oct;12(5):379-84. doi: 10.1007/s10286-002-0049-3.
Abnormalities of cardiac baroreceptor sensitivity (BRS) may contribute towards the high prevalence of orthostatic hypotension and falls in the elderly. Most mathematical analyses used to determine BRS in the time or frequency domains assume a stationary physiological state and cannot be performed under dynamic change and therefore are not valid during tilt. We describe a new method of estimating BRS during tilt.
Twenty-five healthy elderly volunteers with a mean age of 69 +/- 3 years underwent head-up tilt to 70 degrees, within 5 s, 3 times on 2 separate visits. Blood pressure (BP) and heart rate were recorded continuously using a Finapres beat-to-beat BP monitor and surface ECG. A continuous estimate of BRS was obtained by combining beat-to-beat linear regression with Legendre polynomial interpolation.
The values for supine BRS prior to tilt on the two visits, calculated using the new regression method (10.4 +/- 8.2 ms/mmHg and 12.5 +/- 9.7 ms/mmHg) were similar to those using fast Fourier analysis (10.7 +/- 6.7 ms/mmHg and 12.4 +/- 7.1 ms/mmHg). A rapid fall in BP and pulse interval along with cardiac BRS values occurred with tilt within the first 20 s of onset on both visits and remained reduced up to 90 s post tilt (p < 0.01).
The values for cardiac BRS obtained using continuous time domain analysis agree well with those calculated using spectral methods and can be used to assess the dynamic changes in BRS to rapid perturbations in BP such as that occur with tilt.
心脏压力感受器敏感性（BRS）异常可能是老年人直立性低血压和跌倒高发的原因之一。大多数用于在时域或频域确定BRS的数学分析都假定生理状态是静止的，无法在动态变化情况下进行，因此在倾斜过程中无效。我们描述了一种在倾斜过程中估计BRS的新方法。
25名平均年龄为69±3岁的健康老年志愿者在5秒内被倾斜至70度头高位，分两次就诊，每次进行3次。使用Finapres逐搏血压监测仪和体表心电图连续记录血压（BP）和心率。通过将逐搏线性回归与勒让德多项式插值相结合，获得BRS的连续估计值。
使用新回归方法计算的两次就诊倾斜前仰卧位BRS值（10.4±8.2毫秒/毫米汞柱和12.5±9.7毫秒/毫米汞柱）与使用快速傅里叶分析计算的值（10.7±6.7毫秒/毫米汞柱和12.4±7.1毫秒/毫米汞柱）相似。两次就诊时，在倾斜开始后的前20秒内，血压和脉搏间期迅速下降，同时心脏BRS值也下降，并且在倾斜后90秒内一直保持降低（p<0.01）。
使用连续时域分析获得的心脏BRS值与使用频谱方法计算的值非常吻合，可用于评估BRS对血压快速扰动（如倾斜时发生的情况）的动态变化。
