Hua Chung-Ching, Yu Chung-Chieh
Chang Gung Memorial Hospital, Keelung, Republic of China.
Chang Gung Memorial Hospital, Keelung, Republic of China.
Chest. 2007 Mar;131(3):750-757. doi: 10.1378/chest.06-1624.
Variability of oxyhemoglobin saturation (Spo(2)) during sleep has been utilized as a diagnostic index for sleep apnea. Spectral analysis with its graphical presentation, the periodogram, is an approach for measuring such variability. This work examined the parameters on a smoothed periodogram created from series data for Spo(2) obtained by pulse oximetry during a sleep study.
Spo(2) was recorded during polysomnography study of 273 subjects. Clinical data of subjects were collected retrospectively. A novel automated algorithm was created to measure the low-frequency (< 0.1 Hz) peak and the slope of spectral density vs frequency in the frequency region of 0.1 to 0.5 Hz (slope(0.1-0.5)). Two successive modified Daniell smoothers with span lengths of 3 to 121 in odd numbers were applied to determine the effect of smoothing on these parameters. slope(0.1-0.5) was least affected by smoothing and had a sensitivity of 78% and a specificity of 80% in diagnosing sleep apnea defined by a value of apnea-hypopnea index >/= 5. Combining slope(0.1-0.5) with parameters of the low-frequency peak enlarged the area under the receiver operating characteristic curve. A composite indicator comprised of slope(0.1-0.5) and ratio of the area under the curve of the low-frequency peak to that of whole periodogram (AUCratio) had a positive likelihood ratio of 15.25 in identifying patients with moderate-to-severe obstructive sleep apnea. The algorithm was validated in another 206 patients undergoing polysomnographic studies.
These analytical results demonstrate that the smoothed periodogram of Spo(2) is a useful tool for screening subjects with sleep apnea.
睡眠期间氧合血红蛋白饱和度（Spo₂）的变异性已被用作睡眠呼吸暂停的诊断指标。频谱分析及其图形表示——周期图，是测量这种变异性的一种方法。这项工作研究了在睡眠研究期间通过脉搏血氧饱和度测定法获得的Spo₂系列数据所创建的平滑周期图上的参数。
在对273名受试者进行多导睡眠图研究期间记录了Spo₂。回顾性收集了受试者的临床数据。创建了一种新颖的自动算法来测量低频（<0.1 Hz）峰值以及0.1至0.5 Hz频率区域内频谱密度与频率的斜率（斜率(0.1 - 0.5)）。应用两个跨度长度为奇数3至121的连续改进丹尼尔平滑器来确定平滑对这些参数的影响。斜率(0.1 - 0.5)受平滑影响最小，在诊断呼吸暂停低通气指数≥5定义的睡眠呼吸暂停时，其灵敏度为78%，特异性为80%。将斜率(0.1 - 0.5)与低频峰值参数相结合可扩大受试者工作特征曲线下的面积。由斜率(0.1 - 0.5)和低频峰值曲线下面积与整个周期图曲线下面积之比（AUCratio）组成的复合指标在识别中重度阻塞性睡眠呼吸暂停患者时的阳性似然比为15.25。该算法在另外206名接受多导睡眠图研究的患者中得到验证。
这些分析结果表明，Spo₂的平滑周期图是筛查睡眠呼吸暂停受试者的有用工具。
