Browsing by Author "He, Wenbo"

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    Skin sympathetic nerve activity in patients with obstructive sleep apnea
    (Elsevier, 2020) He, Wenbo; Tang, Yuzhu; Meng, Guannan; Wang, Danning; Wong, Johnson; Mitscher, Gloria A.; Adams, David; Everett, Thomas H., IV.; Chen, Peng-Sheng; Manchanda, Shalini; Medicine, School of Medicine
    Background: Obstructive sleep apnea (OSA) is associated with increased cardiac arrhythmia and sudden cardiac death. We recently developed a new method (neuECG) to noninvasively measure electrocardiogram and skin sympathetic nerve activity (SKNA). Objective: The purpose of this study was to test the hypothesis that SKNA measured during sleep study is higher in patients with OSA than in those without OSA. Methods: We prospectively recorded neuECG and polysomnography in 26 patients undergoing a sleep study. Sleep stages were scored into rapid eye movement (REM), and non-REM sleep stages 1 (N1), 2 (N2), and 3 (N3). Average voltage of skin sympathetic nerve activity (aSKNA) and SKNA burst area were calculated for quantification. Apnea/hypopnea index (AHI) >5 per hour was used to diagnose OSA. Results: There was a positive correlation (r = 0.549; P = .018) between SKNA burst area and the arousal index in OSA but not in the control group. aSKNA during sleep was 0.61 ± 0.09 μV in OSA patients (n = 18) and 0.53 ± 0.04 μV in control patients (n = 8; P = .025). Burst area was 3.26 (1.90-4.47) μV·s/min in OSA patients and 1.31 (0.67-1.94) μV·s/min in control (P = .047). More apparent differences were found during N2, when the burst area in OSA (3.06 [1.46-5.52] μV·s/min) was much higher than that of the control (0.89 [0.79-1.65] μV·s/min; P = .03). Conclusion: OSA patients have higher SKNA activity than control patients, with the most pronounced differences observed during N2. Arousal at the end of apnea episodes is associated with large SKNA bursts. Overlaps of aSKNA and SKNA burst area between groups suggest that not all OSA patients have increased sympathetic tone.
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    Successful continuous positive airway pressure treatment reduces skin sympathetic nerve activity in patients with obstructive sleep apnea
    (Elsevier, 2022) Meng, Guannan; He, Wenbo; Wong, Johnson; Li, Xiaochun; Mitscher, Gloria A.; Adams, David; Everett, Thomas H., IV; Manchanda, Shalini; Liu, Xiao; Chen, Peng-Sheng; Tang, Yuzhu; Medicine, School of Medicine
    Background: Obstructive sleep apnea (OSA) is associated with cardiovascular diseases and increased sympathetic tone. We previously demonstrated that patients with OSA have increased skin sympathetic nerve activity (SKNA). Objective: The purpose of this study was to test the hypothesis that continuous positive airway pressure (CPAP) treatment reduces SKNA. Methods: The electrocardiogram, SKNA, and polysomnographic recording were recorded simultaneously in 9 patients with OSA. 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 analyses were performed to investigate the frequency spectrum of SKNA. Results: There were very low frequency (VLF), low frequency (LF), and high frequency (HF) oscillations in SKNA. The HF oscillation matched the frequency of respiration. OSA episodes were more frequently associated with the VLF and LF than with the HF oscillations of SKNA. Compared with baseline, CPAP significantly decreased the arousal index and AHI and increased the minimal and mean oxyhemoglobin levels. Optimal treatment significantly increased the dominant frequency and reduced the heart rate, average SKNA (aSKNA), SKNA burst duration, and total burst area. The dominant frequency negatively correlated with aSKNA. Conclusion: VLF, LF, and HF oscillations are observed in human SKNA recordings. Among them, VLF and LF oscillations are associated with OSA while HF oscillations are associated with normal breathing. CPAP therapy reduces aSKNA and shifts the frequency of SKNA oscillation from VLF or LF to HF.