Tilt testing and paced breathing significantly altered the causal couplings between heart period, systolic arterial pressure, and respiration, reflecting modifications in cardiovascular and cardiopulmonary mechanisms.
Observational (n=30)
No
Does an information domain approach detect changes in cardio-vascular, cardio-pulmonary, and vasculo-pulmonary causal couplings during tilt testing and paced breathing in healthy subjects?
An information domain approach can effectively quantify changes in cardiovascular and cardiorespiratory control systems during physiological stressors like tilt testing and paced breathing.
The physiological mechanisms related to cardio-vascular (CV), cardio-pulmonary (CP), and vasculo-pulmonary (VP) regulation may be probed through multivariate time series analysis tools. This study applied an information domain approach for the evaluation of non-linear causality to the beat-to-beat variability series of heart period (t), systolic arterial pressure (s), and respiration (r) measured during tilt testing and paced breathing (PB) protocols. The approach quantifies the causal coupling from the series i to the series j (C(ij)) as the amount of information flowing from i to j. A measure of directionality is also obtained as the difference between two reciprocal causal couplings (D(i,j) = C(ij) - C(ji)). Significant causal coupling and directionality were detected respectively when the median of C(ij) over subjects was positive (C(ij) > 0), and when D(i,j) was statistically different from zero (D(i,j) > 0 or D(i,j) 0). During head-up tilt (up, sp), C(rs) was preserved, C(rt) decreased to zero median, and C(st) and C(ts) increased significantly; directionality vanished between r and t (D(r,t) = 0) and raised from s to t (D(s,t) > 0). During PB (su, pa), C(rs) increased significantly, C(rt) and C(ts) were preserved, and C(st) decreased to zero median; directionality was preserved from r to t (D(r,t) > 0), and raised from r to s (D(r,s) > 0). These results suggest that the approach may reflect modifications of CV, CP, and VP mechanisms consequent to altered physiological conditions, such as the baroreflex engagement and the dampening of respiratory sinus arrhythmia induced by tilt, or the respiratory driving on arterial pressure induced by PB. Thus, it could be suggested as a tool for the non-invasive monitoring of CV and cardiorespiratory control systems in normal and impaired conditions.
Faes et al. (Sat,) conducted a observational in Healthy (n=30). Tilt testing and paced breathing vs. Supine position and spontaneous breathing was evaluated on Causal coupling (C) and directionality (D) indices between heart period, systolic arterial pressure, and respiration. Tilt testing and paced breathing significantly altered the causal couplings between heart period, systolic arterial pressure, and respiration, reflecting modifications in cardiovascular and cardiopulmonary mechanisms.