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, α 1RRI , α 2RRI , α 1Resp , α 2Resp), Multiple Scaling Entropy (MSE RRI1−4 , MSE RRI5−10 , MSE Resp1−4 , MSE Resp5−10), spectral coherence (Coh RRI−Resp), cross DFA (ρ 1 and ρ 2) and cross MSE (X MSE1−4 and X MSE5−10) 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 Coh RRI−Resp and insensitivity to change of in ρ 1 , ρ 2 , X MSE1−4 , and X MSE5−10. 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. Coh RRI−Resp did not change with respect to supine position, while ρ 1 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 α 1 vs. α 2 relationship, which can be accurately expressed by the proposed measure-inter-fractal angle θ. Short scale (α 1 vs. MSE 1−4) and long scale (α 2 vs. MSE 5−10) complexity measures had reciprocal interrelation in standing with 0.1 Hz breathing, with specific cardiorespiratory coupling pattern (ρ 1 vs. X MSE1−4). These results support the hypothesis of hierarchical organization Matić et al. RRI-Respiratory Complexity and Cardiorespiratory Coupling 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.
Objective: In this research we explored the (homeo)dynamic character of cardiorespiratory coupling (CRC) under the influence of different body posture and breathing regimes. Our tool for it was the pulse respiration quotient (PRQ), representing the number of heartbeat intervals per breathing cycle. We obtained non-integer PRQ values using our advanced Matlab® algorithm and applied it on the signals of 20 healthy subjects in four conditions: supine position with spontaneous breathing (Supin), standing with spontaneous breathing (Stand), supine position with slow (0.1 Hz) breathing (Supin01) and standing with slow (0.1 Hz) breathing (Stand01).Main results: Linear features of CRC (in PRQ signals) were dynamically very sensitive to posture and breathing rhythm perturbations. There are obvious increases in PRQ mean level and variability under the separated and joined influence of orthostasis and slow (0.1 Hz) breathing. This increase was most pronounced in Stand01 as the state of joint influences. Importantly, PRQ dynamic modification showed greater sensitivity to body posture and breathing regime changes than mean value and standard deviation of heart rhythm and breathing rhythm. In addition, as a consequence of prolonged supine position, we noticed the tendency to integer quantization of PRQ (especially after 14 min), in which the most common quantization number was 4:1 (demonstrated in other research reports as well). In orthostasis and slow breathing, quantization can also be observed, but shifted to other values. We postulate that these results manifest resonance effects induced by coupling patterns from sympathetic and parasympathetic adjustments (with the second as dominant factor).Significance: Our research confirms that cardiorespiratory coupling adaptability could be profoundly explored by precisely calculated PRQ parameter since cardiorespiratory regulation in healthy subjects is characterized by a high level of autonomic adaptability (responsiveness) to posture and breathing regime, although comparisons with pathological states has yet to be performed. We found Stand01 to be the most provoking state for the dynamic modification of PRQ (cardiorespiratory inducement). As such, Stand01 has the potential of using for PRQ tuning by conditioning the cardiorespiratory autonomic neural networks, e.g., in the cases where PRQ is disturbed by environmental (i.e., microgravity) or pathologic conditions.
Due to the fact that respiratory breath-to-breath and cardiac intervals between two successive R peaks (BBI and RRI, respectively) are not temporally concurrent, in a previous paper, we proposed a method to calculate both the integer and non-integer parts of the pulse respiration quotient (PRQ = BBI/RRI = PRQint + b1 + b2), b1 and b2 being parts of the border RRIs for each BBI. In this work, we study the correlations between BBI and PRQ, as well as those between BBI and mean RRI within each BBI (mRRI), on a group of twenty subjects in four conditions: in supine and standing positions, in combination with spontaneous and slow breathing. Results show that the BBI vs. PRQ correlations are positive; whereas the breathing regime had little or no effect on the linear regression slopes, body posture did. Two types of scatter plots were obtained with the BBI vs. mRRI correlations: one showed points aggregated around the concurrent PRQint lines, while the other showed randomly distributed points. Five out of six of the proposed aggregation measures confirmed the existence of these two cardio-respiratory coupling regimes. We also used b1 to study the positions of R pulses relative to the respiration onsets and showed that they were more synchronous with sympathetic activation. Overall, this method should be used in different pathological states.
The document The Church — Towards a Common Vision (TCTCV) of the Commission for Faith and Order within the World Council of Churches was published in Serbian, as a book, co-published by the Christian Cultural Center “Dr. Radovan Bigović,” Institute for Systematic Theology of the Faculty of Orthodox Theology at the University of Belgrade and Biblical Cultural Center, 2020, at the height of the coronavirus pandemic. Both the TCTCV book and the pandemic represent a spiritual and existential challenge. They provoke reception, reflection. Therefore, it is necessary to capture the contemporary context and meaning of publishing and researching literature dedicated to the topic of ecumenism in our Church. It is also expedient to look at history and significance of ecumenism as a general mission of the Church. The notable ecclesiocentricity of the book TCTCV can arouse our greater interest in orthodox and ecumenical ecclesiology, their comparative research, as well as in re-examining our own role and invocation in the ecumenical movement. Through statistical, epistemological, and contextual analysis of the concepts of the text of the book, we noticed some specifics and possibilities of encouragement for inclusive lay, consultative-democratic, and political-theological approaches in ecumenism. The grace of reading the book TCTCV is manifested, among other things, through arousing contemplation over the mystery of the Church, unity, communion. This secret could be explored mentally and spiritually, through a personal relationship, together, based on the experience of participating in a concreate community of the Church. The axiom about the Church as a community is at the heart of the content of this book, as well as the universal call to the Christ-loving hearts of many to use the book as an instrument for mutual acquaintance, rapprochement, and striving for a common, Eucharistic understanding of the Church and universal Christian unity. In general, this was the vision of Bishop Nicholai Velimirovich while participating in the ecumenical movement and infusing in it his own orthodox experience of the Church. It was also very impactful on prof. Dr. Radovan Bigović, who further elaborated modern ecumenical attitudes, clear and solid guidelines for our contemporary orthodox ecumenical orientation. Both of them, bishop Nicholai and Dr. Bigović are ecumenical and inclusive (unifying) persons and as such our encouraging paragons for ecumenical mission and above all ecumenical love. Relied on them and other ecumenical theologians we are gifted with an opportunity to get involved and to continue building our ecumenical tradition in which publishing plays a significant role.
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