Blasi Anna, Jo Javier Antonio, Valladares Edwin, Juarez Ricardo, Baydur Ahmet, Khoo Michael C K
Department of Biomedical Engineering, University of Southern California, Los Angeles 90080, USA.
IEEE Trans Biomed Eng. 2006 Jan;53(1):74-82. doi: 10.1109/TBME.2005.859789.
Recent studies suggest that exposure to repetitive episodes of hypoxia and transient arousal can lead to increased risk for cardiovascular disease in patients with obstructive sleep apnea syndrome (OSAS). To obtain an improved understanding of and to quantitatively characterize the autonomic effects of arousal from sleep, a time-varying closed-loop model was used to determine the interrelationships among respiration, heart rate and blood pressure in 8 normal adults. A recursive least squares algorithm was used in combination with the Laguerre expansion technique to estimate the time-varying impulse responses of the 4 model components. We found that during arousal: 1) respiratory-cardiac coupling gain increases in nonrapid-eye movement (NREM) but not in REM sleep; 2) in both NREM and REM sleep, baroreflex gain shows an initial increase, but this is followed by a more sustained decrease below pre-arousal baseline levels, allowing sympathetic tone to be elevated over a relatively long duration; 3) the gains of other model components show increases with arousal that are consistent with the increased sympathetic modulation of systemic vascular resistance and contractility of the heart. These findings establish a normative database against which further measurements of cardiovascular arousal responses in OSAS may be compared.
最近的研究表明，阻塞性睡眠呼吸暂停综合征（OSAS）患者反复暴露于缺氧发作和短暂觉醒中会导致心血管疾病风险增加。为了更好地理解并定量表征睡眠觉醒的自主神经效应，我们使用了一个时变闭环模型来确定8名正常成年人呼吸、心率和血压之间的相互关系。递归最小二乘算法与拉盖尔展开技术相结合，用于估计4个模型组件的时变脉冲响应。我们发现，在觉醒期间：1）非快速眼动（NREM）睡眠期间呼吸-心脏耦合增益增加，而快速眼动（REM）睡眠期间则不然；2）在NREM和REM睡眠中，压力反射增益最初都会增加，但随后会持续下降至觉醒前基线水平以下，从而使交感神经张力在相对较长的时间内升高；3）其他模型组件的增益随着觉醒而增加，这与全身血管阻力和心脏收缩力的交感神经调节增加一致。这些发现建立了一个标准数据库，可用于比较OSAS患者心血管觉醒反应的进一步测量结果。
