Analysis of Heart Rate and Heart Rate Variability Immediately After Continuous Positive Airway Pressure Titration in Patients With Moderate to Severe Obstructive Sleep Apnea

Abstract

Background and Objectives Recurrent hypoxia, hypercapnia, and arousal during sleep can induce hyperactivity of the sympathetic nervous system (SNS) in patients with obstructive sleep apnea (OSA), which contributes to the development of hypertension and cardiovascular disease. This study was designed to compare changes in heart rate (HR) and heart rate variability (HRV), both of which reflect the activity of the autonomic nervous system (ANS) in OSA patients before and immediately after continuous positive airway pressure (CPAP) titration.Subjects and Method Thirty-five OSA patients (47.8±12.3 years) and 16 healthy subjects (43.2±12.5 years) were enrolled in this study. A night CPAP titration was performed on the OSA patients, and HRV was calculated by RR intervals from the electrocardiogram signals during the total sleep time.Results The mean age of OSA patients was 47.8 years (M:F=34:1), and the control group was 43.3 years (M:F=14:2). The mean AHI of OSA patients was 53.4±31.9, and decreased 17.3±19.4 after CPAP titration, and 4.3±1.6 in the normal controls. During CPAP titration, the mean HR of OSA patients was 68.0±8.9, which was significantly higher than that of the normal controls, 59.5±9.0 (<i>p</i>=0.003). For HRV, standard deviation of all NN intervals (<i>p</i>=0.001), root mean square of the successive NN intervals (<i>p</i><0.001), and low frequency (LF) (<i>p</i>=0.006) values were significantly decreased after CPAP titration compared to the baseline. After CPAP titration, LF (<i>p</i>=0.017) and LF/HF (<i>p</i>=0.003) values were still significantly higher than those of the normal controls.Conclusion HRV analysis revealed that CPAP titration for one day caused decreased SNS activity but did not induce a balance in ANS when compared to the normal controls.