Journal of Applied Physiology Journal of Neurophysiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
 QUICK SEARCH:   [advanced]


     


J Appl Physiol (October 30, 2008). doi:10.1152/japplphysiol.90822.2008
This Article
Right arrow Full Text (PDF) Free
Right arrow All Versions of this Article:
106/1/153    most recent
90822.2008v1
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Claassen, J. A.H.R.
Right arrow Articles by Zhang, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Claassen, J. A.H.R.
Right arrow Articles by Zhang, R.
Submitted on June 27, 2008
Revised on October 15, 2008
Accepted on October 28, 2008

Dynamic cerebral autoregulation during repeated squat-stand maneuvers

Jurgen A.H.R. Claassen1, Benjamin D. Levine2, and Rong Zhang3*

1 Radboud University Nijmegen Medical Center
2 University of Texas Southwestern
3 Presbyterian Hospital of Dallas

* To whom correspondence should be addressed. E-mail: rongzhang{at}texashealth.org.

Transfer function analysis of spontaneous oscillations in blood pressure (BP) and cerebral blood flow (CBF) can quantify the dynamic relationship between BP and CBF. However, such oscillation amplitudes are often small and of questionable clinical significance, vary substantially, and cannot be controlled. At the very low frequencies (< 0.07Hz) coherence between BP and CBF often is low (< 0.50) and their causal relationship is debated. Eight healthy subjects performed repeated squat-stand maneuvers to induce large oscillations in BP at frequencies of 0.025 and 0.05 (very low frequency) and 0.1 Hz (low frequency) respectively. BP (Finapres), CBF velocity (CBFV, TCD), and end-tidal CO2 (capnography) were monitored. Spectral analysis was used to quantify oscillations in BP and CBFV and to estimate transfer function phase, gain and coherence. Compared with spontaneous oscillations, induced oscillations had higher coherence (mean 0.8 SD 0.11, > 0.5 in all subjects at all frequencies) and lower variability in phase estimates. However, gain estimates remained unchanged. Under both conditions, the "high-pass filter" characteristics of dynamic autoregulation were observed. In conclusion, using repeated squat-stand maneuvers, we were able to study dynamic cerebral autoregulation in the low frequencies under conditions of hemodynamically strong and causally related oscillations in BP and CBFV. This enhances not only the confidence of transfer function analysis as indicated by high coherence and improved phase estimation, but strengthens also the clinical relevance of this method as induced oscillations in BP and CBFV mimic those associated with postural changes in daily life.




This article has been cited by other articles:


Home page
Am. J. Physiol. Heart Circ. Physiol.Home page
A. J. Ocon, M. S. Medow, I. Taneja, D. Clarke, and J. M. Stewart
Decreased upright cerebral blood flow and cerebral autoregulation in normocapnic postural tachycardia syndrome
Am J Physiol Heart Circ Physiol, August 1, 2009; 297(2): H664 - H673.
[Abstract] [Full Text] [PDF]




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Visit Other APS Journals Online
Copyright © 1948 by the American Physiological Society.