The Effect of Obstructive Sleep Apnea on the Cardiovascular Variability

Sleep apnea is a serious medical condition that influence millions of adults and children in the United States. It is unknown whether or not sleep apnea can cause any abnormalities in cardiovascular variability in patients with no cardiovascular disease. In this study, we investigated new cardiovascular variables which correspond with obstructive sleep apnea. The power spectrum of the electrocardiogram signal (ECG) was studied in healthy aged-matched adults $\boldsymbol{(\mathrm{n}=15)}$ and patients diagnosed with moderate obstructive sleep apnea $\boldsymbol{(\mathrm{n}=15)}$. The power spectral analysis was divided into three main frequency bands: very low frequency $\boldsymbol{(0.0033\sim 0.04\mathrm{Hz})}$; low frequency $\boldsymbol{(0.04\sim 0.15\ \mathrm{Hz})}$; and high frequency $\boldsymbol{(0.15\sim 0.4\mathrm{Hz})}$. Frequency domain analysis revealed that the very low frequency component of the ECG signal was increased in obstructive sleep apnea patients during episodes of obstructive sleep apnea, whereas other frequencies (low and high frequency) showed no significant changes. This new cardiovascular variable can be used as a new important feature in any comprehensive obstructive sleep apnea prediction model (to increase the accuracy of the model) or in any other noninvasive approaches for diagnosing or monitoring obstructive sleep apnea at home.