Response of Autonomic Nervous System to Body Positions:
Abstract
Two mathematical methods, the Fourier and wavelet transforms, were used to study the short term cardiovascular control system. Time series, picked from electrocardiogram and arterial blood pressure lasting 6 minutes, were analyzed in supine position (SUP), during the first (HD1) and the second parts (HD2) of 90° head down tilt, and during recovery (REC). The wavelet transform was performed using the Haar function of period T=2j (j=1,2,...,6) to obtain wavelet coefficients. Power spectra components were analyzed within three bands, VLF (0.003-0.04), LF (0.04-0.15) and HF (0.15-0.4) with the frequency unit cycle/interval. Wavelet transform demonstrated a higher discrimination among all analyzed periods than the Fourier transform. For the Fourier analysis, the LF of R-R intervals and VLF of systolic blood pressure show more evident difference for different body positions. For the wavelet analysis, the systolic blood pressures show much more evident differences than the R-R intervals. This study suggests a difference in the response of the vessels and the heart to different body positions. The partial dissociation between VLF and LF results is a physiologically relevant finding of this work.
- Publication:
-
Modern Physics Letters B
- Pub Date:
- 2005
- DOI:
- 10.1142/S0217984905008025
- arXiv:
- arXiv:physics/0310125
- Bibcode:
- 2005MPLB...19...59X
- Keywords:
-
- 87.10.+e;
- 87.80.-y;
- 87.90.+y;
- General theory and mathematical aspects;
- Biological techniques and instrumentation;
- biomedical engineering;
- Other topics in biological and medical physics;
- Physics - Biological Physics;
- Physics - Medical Physics;
- Quantitative Biology - Tissues and Organs
- E-Print:
- RevTex,8 figures