Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions.

Porta A, Gelpi F, Bari V, Cairo B, De Maria B, Tonon D, Rossato G, Ranucci M, Faes L. Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions. IEEE Trans Biomed Eng. 2021 Dec 14;PP. doi: 10.1109/TBME.2021.3135313. Epub ahead of print. PMID: 34905489. Abstract <strong>Objective: </strong>Respiration disturbs cardiovascular and cerebrovascular controls but its role is not fully elucidated. <strong>Methods: </strong>Respiration can be classified as a confounder if its observation reduces the strength of the causal relationship from source to target. Respiration is a suppressor if the opposite situation holds. We prove that a confounding/suppression (C/S) test can be accomplished by evaluating the sign of net redundancy/synergy balance in the predictability framework based on multivariate autoregressive modelling. In addition, we suggest that, under the hypothesis of Gaussian processes, the C/S test can be given in the transfer entropy decomposition framework as well. Experimental protocols: We applied the C/S test to variability series of respiratory movements, heart period, systolic arterial pressure, mean arterial pressure, and mean cerebral blood flow recorded in 17 pathological individuals (age: 648 yrs; 17 males) before and after induction of propofol-based general anesthesia prior to coronary artery bypass grafting, and in 13 healthy subjects (age: 278 yrs; 5 males) at rest in supine position and during head-up tilt with a table inclination of 60. <strong>Results: </strong>Respiration behaved systematically as a confounder for cardiovascular and cerebrovascular controls. In addition, its role was affected by propofol-based general anesthesia but not by a postural stimulus of limited intensity. <strong>Conclusion: </strong>The C/S test can be fruitfully exploited to categorize the role of respiration over causal variability interactions.Porta A、Gelpi F、Bari V、Cairo B、De Maria B、Tonon D、Rossato G、Ranucci M、Faes L. 《呼吸在心血管与脑血管变异性交互作用中的角色分类》，发表于《IEEE生物医学工程汇刊》（IEEE Trans Biomed Eng），2021年12月14日在线优先出版（Epub ahead of print），DOI: 10.1109/TBME.2021.3135313，PMID: 34905489。 【研究目的】：呼吸会干扰心血管与脑血管的调控过程，但其具体作用尚未完全阐明。 【研究方法】：若观测呼吸能够削弱从源变量到目标变量的因果关联强度，则可将呼吸归类为混杂变量（confounder）；若情况相反，则呼吸为抑制变量（suppressor）。本文证明，基于多元自回归建模（multivariate autoregressive modelling）的可预测性框架下，可通过评估净冗余/协同平衡的符号来完成混杂/抑制（C/S）检验。此外，本文提出，在高斯过程假设下，C/S检验也可在传递熵（transfer entropy）分解框架下实现。 【实验方案】：我们将C/S检验应用于两类受试者的生理变异性序列：其一为17名病理受试者（年龄：64.8岁；17名男性），采集其行冠状动脉旁路移植术（coronary artery bypass grafting）前，接受丙泊酚（propofol）全身麻醉诱导前后的生理信号；其二为13名健康受试者（年龄：27.8岁；5名男性），分别采集其仰卧静息状态与倾斜角度为60°的头高脚低位时的生理信号。检测的生理序列包括呼吸运动、心周期、收缩动脉压、平均动脉压以及平均脑血流量。 【研究结果】：呼吸在心血管与脑血管的调控交互作用中系统性地表现为混杂变量。此外，其作用会受到丙泊酚全身麻醉的影响，但不会受到低强度体位刺激的影响。 【结论】：C/S检验可有效用于分类呼吸在因果变异性交互作用中的角色。