| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Cardiorespiratory and Vascular Dynamics Laboratory, Faculty of Applied Health Sciences, University of waterloo, Waterloo, Ontario, Canada N2L 3G1
Cerebrovascular autoregulation is
evaluated from spontaneous fluctuations in mean flow velocity (MFV) by
transcranial Doppler ultrasound of the middle cerebral artery (MCA)
with respect to changes in arterial blood pressure (BPMCA),
but the effects of spontaneous fluctuations in arterial
PCO2 on MFV have been largely ignored.
Autoregressive moving average analysis (ARMA), a closed-loop system
identification technique, was applied to data from nine healthy
subjects during spontaneous breathing, during inspiration of 10%
CO2 for two breaths once per minute for 4 min, and during sustained breathing of 7% CO2. Cerebrovascular resistance
index (CVRi) was calculated (CVRi = BPMCA/MFV).
Reliable estimates of gain for BPMCA 
MFV were obtained
for spontaneous breathing and the two-breath method. In contrast,
reliable gain estimates for PCO2 MFV or
PCO2 CVRi were achieved only under the
two-breath method. PCO2 MFV gain was
smaller with the two-breath method than during sustained 7%
CO2 (P < 0.05). BPMCA was
elevated by 7% CO2 but not by the two-breath method. The
closed-loop model provides insight into interactions between
BPMCA and PCO2 on cerebrovascular control, but reliable solutions for PCO2
effects with ARMA analysis require perturbation by the two-breath method.
autoregressive moving average analysis modeling; arterial carbon dioxide partial pressure; Doppler ultrasound; cerebral blood flow; autoregulation
This article has been cited by other articles:
|
|
 |
|
  C. Murrell, L. Wilson, J. D. Cotter, S. Lucas, S. Ogoh, K. George, and P. N. Ainslie Alterations in autonomic function and cerebral hemodynamics to orthostatic challenge following a mountain marathon J Appl Physiol, July 1, 2007; 103(1): 88 - 96. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. H. R. Claassen, R. Zhang, Q. Fu, S. Witkowski, and B. D. Levine Transcranial Doppler estimation of cerebral blood flow and cerebrovascular conductance during modified rebreathing J Appl Physiol, March 1, 2007; 102(3): 870 - 877. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. D. Mitsis, R. Zhang, B. D. Levine, and V. Z. Marmarelis Cerebral hemodynamics during orthostatic stress assessed by nonlinear modeling J Appl Physiol, July 1, 2006; 101(1): 354 - 366. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. B. Panerai, M. Moody, P. J. Eames, and J. F. Potter Dynamic cerebral autoregulation during brain activation paradigms Am J Physiol Heart Circ Physiol, September 1, 2005; 289(3): H1202 - H1208. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Serrador, F. A. Sorond, M. Vyas, M. Gagnon, I. D. Iloputaife, and L. A. Lipsitz Cerebral pressure-flow relations in hypertensive elderly humans: transfer gain in different frequency domains J Appl Physiol, January 1, 2005; 98(1): 151 - 159. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. R. Edwards, D. L. Devitt, and R. L. Hughson Two-breath CO2 test detects altered dynamic cerebrovascular autoregulation and CO2 responsiveness with changes in arterial PCO2 Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2004; 287(3): R627 - R632. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
