Bloomfield D M, Zweibel S, Bigger J T, Steinman R C
Department of Medicine, Columbia University, New York, New York 10032, USA.
Am J Physiol. 1998 May;274(5):H1761-6. doi: 10.1152/ajpheart.1998.274.5.H1761.
High-frequency power, measured from power spectral analysis of R-R variability, reflects vagal modulation of the sinus node. Unexpectedly, a recent study reported a decrease in high-frequency power during the infusion of phenylephrine despite a prolongation of R-R intervals, indicating an increase in vagal activity. To better define the limitations of high-frequency power to quantify vagal modulation, we measured high-frequency power during the infusion of phenylephrine (0.4, 0.8, and 1.2 micrograms.kg-1.min-1) into 10 normal subjects. We found increasing doses of phenylephrine produced progressive increases in systolic blood pressure from 118 +/- 4 to 129 +/- 5 mmHg (P < 0.005), R-R intervals from 881 +/- 44 to 1,274 +/- 69 ms (P < 0.0001), and the logarithm of high-frequency power from 5.83 +/- 0.22 to 7.73 +/- 0.24 ln(ms2) (P < 0.0001). The conclusion was high-frequency power increases with increasing doses of phenylephrine. These data strongly support the ability of high-frequency power to detect an increase in vagal modulation during baroreceptor activation from an increase in systolic blood pressure with the infusion of phenylephrine.
通过R-R间期的功率谱分析测得的高频功率反映了窦房结的迷走神经调制。出乎意料的是，最近一项研究报告称，在输注去氧肾上腺素期间，尽管R-R间期延长，但高频功率却降低，这表明迷走神经活动增加。为了更好地界定高频功率在量化迷走神经调制方面的局限性，我们对10名正常受试者输注去氧肾上腺素（0.4、0.8和1.2微克·千克⁻¹·分钟⁻¹）期间测量了高频功率。我们发现，去氧肾上腺素剂量增加使收缩压从118±4 mmHg逐步升高至129±5 mmHg（P<0.005），R-R间期从881±44毫秒延长至1274±69毫秒（P<0.0001），高频功率的对数从5.83±0.22升至7.73±0.24 ln(ms²)（P<0.0001）。结论是高频功率随去氧肾上腺素剂量增加而升高。这些数据有力地支持了高频功率能够检测到在输注去氧肾上腺素导致收缩压升高从而激活压力感受器期间迷走神经调制增加的能力。
