Vagal modulation of RR intervals during head-up tilt and the infusion of isoproterenol.
Vagal modulation of RR intervals during head-up tilt and the infusion of isoproterenol.
复制标题
抬头倾斜和异丙肾上腺素输注期间迷走神经对 RR 间隔的调节。
DOI：
10.1016/s0002-9149(99)80747-4
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Steinman,RC
中科院分区：
文献类型：
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作者：
Bloomfield,DM;BiggerJr,JT;Pavri,BB;Han,J;Fleiss,JL;Rolnitzky,LM;Steinman,RC
本研究的目的是描述2种干预措施（头高位倾斜和异丙肾上腺素输注）的自主神经效应，这些干预措施通过不同的机制改变自主神经平衡，但产生相同的RR间期。我们比较了头高位倾斜与异丙肾上腺素对自主神经平衡的影响，通过RR变异性的功率谱分析来测量。15名正常受试者进行基线测量，然后进行头高位倾斜。恢复至基线仰卧位值后，以1 μg/min的速率输注异丙肾上腺素（低剂量异丙肾上腺素），然后将速率增加至2.1 ± 0.5 μg/min（高剂量异丙肾上腺素）。所有受试者在高剂量异丙肾上腺素治疗期间接受第二次倾斜，9例受试者完成了第二次倾斜研究。在实验过程中，记录正常RR间期，并使用5分钟片段计算功率谱。使用高频（HF）功率（0.15至0.40 Hz）作为迷走神经活动的测量。将头高位倾斜的效果与小剂量异丙肾上腺素的效果进行比较。尽管平均RR间期几乎相同（倾斜时为784 ms，低剂量异丙肾上腺素时为792 ms，p = NS），但在无药物状态下头高位倾斜时的HF功率（172 ms 2）显著（p < 0.05）低于仰卧位低剂量异丙肾上腺素时的HF功率（307 ms 2）。在输注高剂量异丙肾上腺素期间进行第二次头高位倾斜。在高剂量异丙肾上腺素治疗期间，倾斜导致RR间期缩短（从573至491 ms; p < 0.01）和HF功率降低（从68至28 ms 2; p < 0.05）。倾斜的自主反应，测量RR间期和HF功率的相对变化，是相似的，无论是在无药状态下进行倾斜或在输注异丙肾上腺素，总之，有较少的迷走神经调制RR间期倾斜期间比低剂量异丙肾上腺素输注，尽管相似的RR间期。尽管高剂量异丙肾上腺素可使RR间期缩短，但倾斜引起迷走神经活动显著减少。RR变异性的功率谱分析可以区分产生相似RR间期的不同自主神经状态。
The objective of this study was to characterize the autonomic effects of 2 interventions, head-up tilt and isoproterenol infusion, which alter autonomic balance by different mechanisms but produce the same RR intervals. We compared the effect of head-up tilt with the effect of isoproterenol on autonomic balance as measured by power spectral analysis of RR variability. Fifteen normal subjects had baseline measurements and then underwent head-up tilt. After return to baseline supine values, isoproterenol was infused at a rate of 1 μg/min (low-dose isoproterenol), which was then increased to 2.1 ± 0.5 μg/min (high-dose isoproterenol). All subjects underwent a second tilt during high-dose isoproterenol, and 9 subjects completed this second tilt study. During the experiment, normal RR intervals were recorded and 5-minute segments were used to calculate power spectra. High-frequency (HF) power (0.15 to 0.40 Hz) was used as a measure of vagal activity. The effects of head-up tilt were compared with the effects of low-dose isoproterenol. Despite nearly identical mean RR intervals (784 ms with tilt vs 792 ms with low-dose isoproterenol, p = NS), there was significantly (p < 0.05) less HF power during head-up tilt in the drugfree state (172 ms2) than during low-dose isoproterenol in the supine position (307 ms2). A second head-up tilt was performed during the infusion of high-dose isoproterenol. During high-dose isoproterenol, tilt caused a decrease in RR intervals (from 573 to 491 ms; p < 0.01) and a decrease in HF power (from 68 to 28 ms2; p < 0.05). The autonomic response to tilt, as measured by relative changes in RR interval and HF power, was similar whether tilt was performed in the drugfree state or during the infusion of isoproterenol, In conclusion, there was less vagal modulation of RR intervals during tilt than during low-dose isoproterenol infusion despite similar RR intervals. Despite the short RR intervals achieved with high-dose isoproterenol, tilt caused a striking decrease in vagal activity. Power spectral analysis of RR variability can distinguish between different autonomic states that produce similar RR intervals.