Data_Sheet_2_Slow 0.1 Hz Breathing and Body Posture Induced Perturbations of RRI and Respiratory Signal Complexity and Cardiorespiratory Coupling.docx

Objective: We explored the physiological background of the non-linear operating mode of cardiorespiratory oscillators as the fundamental question of cardiorespiratory homeodynamics and as a prerequisite for the understanding of neurocardiovascular diseases. We investigated 20 healthy human subjects for changes using electrocardiac RR interval (RRI) and respiratory signal (Resp) Detrended Fluctuation Analysis (DFA, α1RRI, α2RRI, α1Resp, α2Resp), Multiple Scaling Entropy (MSERRI1−4, MSERRI5−10, MSEResp1−4, MSEResp5−10), spectral coherence (CohRRI−Resp), cross DFA (ρ1 and ρ2) and cross MSE (XMSE1−4 and XMSE5−10) indices in four physiological conditions: supine with spontaneous breathing, standing with spontaneous breathing, supine with 0.1 Hz breathing and standing with 0.1 Hz breathing. Main results: Standing is primarily characterized by the change of RRI parameters, insensitivity to change with respiratory parameters, decrease of CohRRI−Resp and insensitivity to change of in ρ1, ρ2, XMSE1−4, and XMSE5−10. Slow breathing in supine position was characterized by the change of the linear and non-linear parameters of both signals, reflecting the dominant vagal RRI modulation and the impact of slow 0.1 Hz breathing on Resp parameters. CohRRI−Resp did not change with respect to supine position, while ρ1 increased. Slow breathing in standing reflected the qualitatively specific state of autonomic regulation with striking impact on both cardiac and respiratory parameters, with specific patterns of cardiorespiratory coupling. Significance: Our results show that cardiac and respiratory short term and long term complexity parameters have different, state dependent patterns. Sympathovagal non-linear interactions are dependent on the pattern of their activation, having different scaling properties when individually activated with respect to the state of their joint activation. All investigated states induced a change of α1 vs. α2 relationship, which can be accurately expressed by the proposed measure—inter-fractal angle θ. Short scale (α1 vs. MSE1−4) and long scale (α2 vs. MSE5−10) complexity measures had reciprocal interrelation in standing with 0.1 Hz breathing, with specific cardiorespiratory coupling pattern (ρ1 vs. XMSE1−4). These results support the hypothesis of hierarchical organization of cardiorespiratory complexity mechanisms and their recruitment in ascendant manner with respect to the increase of behavioral challenge complexity. Specific and comprehensive cardiorespiratory regulation in standing with 0.1 Hz breathing suggests this state as the potentially most beneficial maneuver for cardiorespiratory conditioning.研究目的：本研究旨在探究心肺振荡器（cardiorespiratory oscillators）非线性运行模式的生理学基础，该模式是心肺内稳态动力学（cardiorespiratory homeodynamics）的核心问题，亦是理解神经心血管疾病的必要前提。本研究纳入20名健康受试者，在四种生理状态下，采用心电RR间期（electrocardiac RR interval, RRI）、呼吸信号（respiratory signal, Resp）的去趋势波动分析（Detrended Fluctuation Analysis, DFA，含α1RRI、α2RRI、α1Resp、α2Resp）、多尺度熵（Multiple Scaling Entropy，含MSERRI1−4、MSERRI5−10、MSEResp1−4、MSEResp5−10）、频谱相干性（CohRRI−Resp）、交叉去趋势波动分析（cross DFA，含ρ1与ρ2）以及交叉多尺度熵（cross MSE，含XMSE1−4与XMSE5−10）等指标，分析各指标的变化情况。四种生理状态分别为：自主呼吸仰卧位、自主呼吸直立位、0.1Hz节律呼吸仰卧位、0.1Hz节律呼吸直立位。 主要结果：直立位状态下，主要表现为RRI参数发生显著改变，呼吸参数无明显变化，CohRRI−Resp水平降低，且ρ1、ρ2、XMSE1−4与XMSE5−10无显著改变。仰卧位0.1Hz节律呼吸状态下，两类信号的线性与非线性参数均出现变化，反映了迷走神经对RRI的主导性调控作用，以及0.1Hz慢呼吸对呼吸参数的影响。该状态下CohRRI−Resp与自主呼吸仰卧位相比无明显变化，但ρ1有所升高。直立位0.1Hz节律呼吸状态则呈现出自主神经调控的质性特异性改变，对心脏与呼吸参数均产生显著影响，且伴随特异性心肺耦合模式。 研究意义：本研究结果表明，心脏与呼吸的短期、长期复杂度参数呈现出不同的状态依赖性模式。交感-迷走神经的非线性相互作用依赖于其激活模式，当单独激活与联合激活时，其尺度特性存在差异。所有被研究的生理状态均会改变α1与α2的比值关系，这一关系可通过本研究提出的指标——分形间夹角θ（inter-fractal angle θ）进行精准量化。在0.1Hz节律呼吸直立位状态下，短期尺度（α1与MSE1−4）与长期尺度（α2与MSE5−10）的复杂度指标呈现出相互关联的关系，同时伴随特异性心肺耦合模式（ρ1与XMSE1−4）。上述结果支持心肺复杂度机制具有层级化组织的假说，且该机制会随着行为挑战复杂度的提升以递进方式被募集。0.1Hz节律呼吸直立位状态下特异性且全面的心肺调控效应，提示该状态或许是心肺功能训练中潜在的最优干预方式。