Multivariate dynamic analysis of cerebral blood flow regulation in humans

• Published in: IEEE transactions on biomedical engineering Vol. 47; no. 3; pp. 419 - 423
• Main Authors: Panerai, R.B., Simpson, D.M., Deverson, S.T., Mahony, P., Hayes, P., Evans, D.H.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2000; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adult; Arterial blood pressure; Biological and medical sciences; Blood; Blood flow; Blood pressure; Blood Pressure - physiology; Calibration; Carbon Dioxide - blood; Cerebrovascular Circulation - physiology; Circulatory system; Correlation methods; Finite impulse response filter; Flow velocity; Fluctuations; Fourier Analysis; Human engineering; Humans; Input variables; Investigative techniques, diagnostic techniques (general aspects); Laser-Doppler Flowmetry - methods; Least squares approximations; Mathematical models; Mean square error methods; Mean square errors; Medical sciences; Middle Aged; Models, Biological; Monte Carlo Method; Nervous system; Neurology; Numerical analysis; Reference Values; Signal processing; Signal Processing, Computer-Assisted; Testing; Tidal Volume - physiology; Transfer functions; Ultrasonic investigative techniques; Sonography; Doppler ultrasound study; Human; Carbon dioxide; Central nervous system; Multivariate analysis; Blood flow; Cross correlation; Self regulation; Flow velocity; Circulatory system; Hemodynamics; Transfer function; Brain (vertebrata)
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/10.827312

The contributions of beat-to-beat changes in mean arterial blood pressure (MABP) and breath-by-breath fluctuations in end-tidal CO/sub 2/ (EtCO/sub 2/) as determinants of the spontaneous variability of cerebral blood flow velocity (CBFV) were studied in 16 normal subjects at rest. The two input variables (MABP and EtCO/sub 2/) had significant cross-correlations with CBFV but not between them. Transfer functions were estimated as the multivariate least mean square finite impulse response causal filters. MABP showed a very significant effect in explaining CBFV variability (p<10/sup -11/, Fisher's aggregated-p test) and the model mean square error was significantly reduced (p<0.001) by also including the contribution EtCO/sub 2/. The estimated mean CBFV step response to MABP displayed the characteristic return to baseline caused by the cerebral autoregulatory response. The corresponding response to EtCO/sub 2/ showed a gradual rise taking approximately 10 s to reach a plateau of 2.5%/mmHg. This study demonstrated that spontaneous fluctuations in EtCO/sub 2/ can help to explain the CBFV variability at rest if appropriate signal processing techniques are employed to address the limited power and bandwidth of the breath-by-breath EtCO/sub 2/ signal.