Impact of respiration on cardiovascular coupling using Granger causality analysis in healthy subjects

• Published in: Biomedical signal processing and control Vol. 43; pp. 196 - 203
• Main Authors: Helen Mary, M.C., Singh, Dilbag, Deepak, K.K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2018
• Subjects: Deep breathing; Respiration; RR interval; Spectral analysis; Systolic blood pressure; RR interval; Systolic blood pressure; Deep breathing; Respiration; Spectral analysis
• ISSN: 1746-8094; 1746-8108
• DOI: 10.1016/j.bspc.2018.03.008

Directed coherence (DC) analysis can separate each component (RESP, SBP and RR) of recorded signal but the traditional power spectral density (PSD) cannot show the individual frequency distribution of each component. [Display omitted] •Detect interaction changes among cardiac, vascular and respiratory system during deep breathing.•Interaction is evaluated using frequency domain Granger causality based on directed coherence.•Respiration affects the cardiac system during both normal and deep breathing.•Deep breathing increases respiration effect on vascular system hence blood pressure reduces. This quantitative study delineates the influence of respiratory rate on cardiovascular signal in healthy subjects using granger causality approach. Electrocardiogram (RR), arterial blood pressure (SBP) and respiration (RESP) were simultaneously recorded for 5 min from 20 subjects during normal (13–20 cycles/min) and deep breathing (5 cycles/min) with equal inspiration and expiration time. During deep breathing mean RR remains same but the variance increases. Also deep breathing lowers blood pressure, increases baroreflex sensitivity and improves oxygen saturation. The traditional frequency domain methods based power spectrum analysis and coherence analysis lacks to measure coupling changes among physiological subsystems. Therefore, frequency domain Granger causality method based on directed coherence is proposed to detect the changes in coupling strength among cardiovascular signals under different respiration rates. Directed coherence spectrum can separate RESP, SBP and RR components from each recorded signals. The RESP component of both RR (RRRESP) and SBP (SBPRESP) increases (coherence > 0.5) significantly during deep breathing indicate that respiration affects both cardiac and vascular system but at normal breathing only cardiac system (RRRESP) get affected by respiration. Also a significant increase in coherence is observed on baroreflex direction (RRSBP) indicating that deep breathing controls blood pressure. Hence, the observed directed coherence spectrum helps to detect coupling changes among cardiac, vascular and respiratory signal during autonomic regulation.