Patwardhan A R, Evans J M, Bruce E N, Eckberg D L, Knapp C F
Center for Biomedical Engineering, University of Kentucky, Lexington 40506, USA.
J Appl Physiol (1985). 1995 Jun;78(6):2087-94. doi: 10.1152/jappl.1995.78.6.2087.
Variations in respiratory pattern influence the heart rate spectrum. It has been suggested, hence, that metronomic respiration should be used to correctly assess vagal modulation of heart rate by using spectral analysis. On the other hand, breathing to a metronome has been reported to increase heart rate spectral power in the high- or respiratory frequency region; this finding has led to the suggestion that metronomic respiration enhances vagal tone or alters vagal modulation of heart rate. To investigate whether metronomic breathing complicates the interpretation of heart rate spectra by altering vagal modulation, we recorded the electrocardiogram and respiration from eight volunteers during three breathing trials of 10 min each: 1) spontaneous breathing (mean rate of 14.4 breaths/min); 2) breathing to a metronome at the rate of 15, 18, and 21 breaths/min for 2, 6, and 2 min, respectively; and 3) breathing to a metronome at the rate of 18 breaths/min for 10 min. Data were also collected from eight volunteers who breathed spontaneously for 20 min and breathed metronomically at each subject's mean spontaneous breathing frequency for 20 min. Results from the three 10-min breathing trials showed that heart rate power in the respiratory frequency region was smaller during metronomic breathing than during spontaneous breathing. This decrease could be explained fully by the higher breathing frequencies used during trials 2 and 3 of metronomic breathing. When the subjects breathed metronomically at each subject's mean breathing frequency, the heart rate powers during metronomic breathing were similar to those during spontaneous breathing. Our results suggest that vagal modulation of heart rate is not altered and vagal tone is not enhanced during metronomic breathing.
呼吸模式的变化会影响心率频谱。因此，有人建议应使用节拍呼吸法，通过频谱分析来正确评估心率的迷走神经调节。另一方面，据报道，按照节拍器呼吸会增加高频或呼吸频率区域的心率频谱功率；这一发现导致有人提出节拍呼吸会增强迷走神经张力或改变心率的迷走神经调节。为了研究节拍呼吸是否会通过改变迷走神经调节而使心率频谱的解读变得复杂，我们记录了8名志愿者在每次持续10分钟的三次呼吸试验中的心电图和呼吸情况：1）自主呼吸（平均呼吸频率为14.4次/分钟）；2）分别以15、18和21次/分钟的频率跟随节拍器呼吸2、6和2分钟；3）以18次/分钟的频率跟随节拍器呼吸10分钟。我们还收集了另外8名志愿者的数据，他们自主呼吸20分钟，然后以各自的平均自主呼吸频率跟随节拍器呼吸20分钟。三次10分钟呼吸试验的结果表明，节拍呼吸期间呼吸频率区域的心率功率低于自主呼吸期间。这种降低完全可以由节拍呼吸试验2和试验3中使用的较高呼吸频率来解释。当受试者以各自的平均呼吸频率跟随节拍器呼吸时，节拍呼吸期间的心率功率与自主呼吸期间相似。我们的结果表明，节拍呼吸期间心率的迷走神经调节没有改变，迷走神经张力也没有增强。
