Chaicharn Jarree, Lin Zheng, Chen Maida L, Ward Sally L D, Keens Thomas, Khoo Michael C K
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089-1111, USA.
Sleep. 2009 Jul;32(7):927-38. doi: 10.1093/sleep/32.7.927.
To quantitatively assess daytime autonomic cardiovascular control in pediatric subjects with and without obstructive sleep apnea syndrome (OSAS).
Respiration, R-R intervals, and noninvasive continuous blood pressure were monitored in awake subjects in the supine and standing postures, as well as during cold face stimulation.
Sleep disorders laboratory in a hospital setting.
Ten pediatric patients (age 11.4 +/- 3.6 years) with moderate to severe OSAS (obstructive apnea-hypopnea index = 21.0 +/- 6.6/1 h) before treatment and 10 age-matched normal control subjects (age 11.5 +/- 3.7 years).
Spectral analysis of heart rate variability revealed that high-frequency power was similar and the ratio of low- to high-frequency power was lower in subjects with OSAS vs control subjects. The closed-loop minimal model allowed heart rate variability to be partitioned into a component mediated by respiratory-cardiac coupling and a baroreflex component, whereas blood pressure variability was assumed to result from the direct effects of respiration and fluctuations in cardiac output. Baroreflex gain was lower in subjects with OSAS vs control subjects. Under orthostatic stress, respiratory-cardiac coupling gain decreased in both subject groups, but baroreflex gain decreased only in controls. The model was extended to incorporate time-varying parameter changes for analysis of the data collected during cold face stimulation: cardiac output gain increased in controls but remained unchanged in OSAS.
Our findings suggest that vagal modulation of the heart remains relatively normal in pediatric subjects with OSAS. However, baseline cardiovascular sympathetic activity is elevated, and reactivity to autonomic challenges is impaired.
定量评估患有和未患有阻塞性睡眠呼吸暂停综合征（OSAS）的儿科受试者白天的自主心血管控制情况。
在清醒受试者处于仰卧位和站立位时以及冷脸刺激期间，监测呼吸、R-R间期和无创连续血压。
医院环境中的睡眠障碍实验室。
10名中度至重度OSAS患儿（治疗前，年龄11.4±3.6岁，阻塞性呼吸暂停低通气指数=21.0±6.6/1小时）和10名年龄匹配的正常对照受试者（年龄11.5±3.7岁）。
心率变异性的频谱分析显示，OSAS受试者的高频功率与对照受试者相似，低频与高频功率之比更低。闭环最小模型可将心率变异性分为由呼吸-心脏耦合介导的成分和压力反射成分，而血压变异性被认为是由呼吸的直接影响和心输出量波动导致的。OSAS受试者的压力反射增益低于对照受试者。在直立应激下，两个受试者组的呼吸-心脏耦合增益均降低，但压力反射增益仅在对照组中降低。该模型被扩展以纳入时变参数变化，用于分析冷脸刺激期间收集的数据：对照组的心输出量增益增加，而OSAS组保持不变。
我们的研究结果表明，患有OSAS的儿科受试者心脏的迷走神经调节相对正常。然而，基线心血管交感神经活动升高，对自主神经挑战的反应性受损。
