Acute effects of obstructive sleep apnea on autonomic nervous system, arterial stiffness and heart rate in newly diagnosed untreated patients

Introduction In order to realize the acute effects of obstructive sleep apnea, we investigated newly diagnosed untreated patients with whole night PSG test. The ECG (ElectroCardioGraphy), EEG (ElectroEncephaloGraphy), and Plethysmography were analyzed to generate estimation of variables by methods which include HRV (Heart Rate Variability), DFA (Detrend Fluctuation Analysis), EEG Power Spectrum, QT corrected (QTc) intervals, PTT (Pulse Transit Time), PWV (Pulse Wave Velocity), and CoHrR (Coherence of Heart rate/Respiration). Materials and methods We investigated 226 newly diagnosed untreated patients on the sleep structures and apnea/hypopnea events. For HRV analysis, 5-min good ECG was needed to generate stable biomarkers because there are only 13 subjects with 5-min good EKG data during SWS (Slow Wave Sleep) with apnea or hypopnea. Therefore, we focused the analysis only on sleep stage 2 (S2) and REM (Rapid Eye Movement). In order to compare the states with/without apnea or hypopnea, we only chose the first good 5-min ECG epoch from begin of S2 and REM period with or without apnea/hypopnea respectively. Then we performed a pair-to-pair T -test by subject self-comparison of with/without sleep apnea for each estimation of variables. Results For S2 with apnea/hypopnea, we found that HR, VLF, LF, LFnu, HF, SDNN, RMSDD, NN50, pNN50, DFA alpha, QTc SD, EEG beta, EEG gamma, PWV and PTT SD are increased with statistical significance. And that CoHrR, QTVi, PTT, and EEG theta are decreased with statistical significance. We inferred that the acute effects of sleep apnea on S2 increased the tension of ANS (Autonomic Nervous System) and arterial stiffness and decreased the coherence of heart rate/respiration. For REM with apnea/hypopnea, we found that HR, VLF, SDNN, NN50, DFA alpha, QTc SD, EEG beta percentage, and PWV are increased with statistical significance. And that CoHrR, QTVi, and PTT are decreased with statistical significance. We inferred that the acute effects of sleep apnea on REM contribute to increase on heart rate and arterial stiffness. Conclusion The most different results of apnea effects on REM to S2 were REM affects HR while S2 affects ANS. And the common effects are increased on arterial stiffness, DFA alpha and decreased on coherence of heart rate/respiration.