Obstructive sleep apnea (OSA) is associated with cardiovascular diseases and increased sympathetic tone. We previously demonstrated that OSA patients have increased skin sympathetic nerve activity (SKNA).
To test the hypothesis that continuous positive airway pressure (CPAP) treatment reduces SKNA.
The ECG, SKNA, and polysomnography were recorded simultaneously in 9 OSA patients. After baseline recording, CPAP titration was performed and the pressure was adjusted gradually for the optimal treatment, defined by reducing the apnea-hypopnea index (AHI) to ≤ 5/h. Otherwise the treatment was considered suboptimal (AHI > 5/h). Fast Fourier transform (FFT) analyses were conducted to investigate the frequency spectrum of SKNA.
There were very low frequency (VLF), low frequency (LF) and high frequency (HF) oscillations in the SKNA. The HF oscillation matched the frequency of respiration. OSA episodes were more frequently associated with the VLF and LF than HF oscillations of the SKNA. Compared with baseline, CPAP significantly decreased the arousal index, AHI, and increased the minimal and average O saturation. Optimal treatment significantly increased the dominant frequency (DF), and reduced the heart rate, average SKNA (aSKNA), SKNA burst duration and total burst area. The DF negatively correlated with aSKNA.
VLF, LF and HF oscillations are observed in human SKNA recordings. Among them, VLF and LF are associated with OSA while HF is associated with normal breathing. CPAP therapy reduces the aSKNA and shifts the frequency of SKNA oscillation from VLF or LF to HF.

Copyright © 2021. Published by Elsevier Inc.