Multimodal pressure-flow method to assess dynamics of cerebral autoregulation in stroke and hypertension
Open Access
- 25 October 2004
- journal article
- research article
- Published by Springer Science and Business Media LLC in BioMedical Engineering OnLine
- Vol. 3 (1), 39
- https://doi.org/10.1186/1475-925x-3-39
Abstract
This study evaluated the effects of stroke on regulation of cerebral blood flow in response to fluctuations in systemic blood pressure (BP). The autoregulatory dynamics are difficult to assess because of the nonstationarity and nonlinearity of the component signals.We studied 15 normotensive, 20 hypertensive and 15 minor stroke subjects (48.0 +/- 1.3 years). BP and blood flow velocities (BFV) from middle cerebral arteries (MCA) were measured during the Valsalva maneuver (VM) using transcranial Doppler ultrasound.A new technique, multimodal pressure-flow analysis (MMPF), was implemented to analyze these short, nonstationary signals. MMPF analysis decomposes complex BP and BFV signals into multiple empirical modes, representing their instantaneous frequency-amplitude modulation. The empirical mode corresponding to the VM BP profile was used to construct the continuous phase diagram and to identify the minimum and maximum values from the residual BP (BPR) and BFV (BFVR) signals. The BP-BFV phase shift was calculated as the difference between the phase corresponding to the BPR and BFVR minimum (maximum) values. BP-BFV phase shifts were significantly different between groups. In the normotensive group, the BFVR minimum and maximum preceded the BPR minimum and maximum, respectively, leading to large positive values of BP-BFV shifts.In the stroke and hypertensive groups, the resulting BP-BFV phase shift was significantly smaller compared to the normotensive group. A standard autoregulation index did not differentiate the groups. The MMPF method enables evaluation of autoregulatory dynamics based on instantaneous BP-BFV phase analysis. Regulation of BP-BFV dynamics is altered with hypertension and after stroke, rendering blood flow dependent on blood pressure.Keywords
This publication has 27 references indexed in Scilit:
- Evaluation of Impaired Cerebral Autoregulation by the Valsalva ManeuverStroke, 1996
- Accuracy of 133-xenon regional cerebral blood flow and quantitative electroencephalography in systemic lupus erythematosusLupus, 1996
- Can Transcranial Doppler Really Detect Reduced Cerebral Perfusion States?Stroke, 1995
- Cerebral blood flow and resistances during hypotensive haemorrhage in the rabbit: transcranial Doppler and laser‐Doppler flowmetryClinical Physiology and Functional Imaging, 1995
- Phase Relationship Between Cerebral Blood Flow Velocity and Blood PressureStroke, 1995
- Effects of the Valsalva Maneuver on Cerebral Circulation in Healthy AdultsStroke, 1995
- Comparison of Static and Dynamic Cerebral Autoregulation MeasurementsStroke, 1995
- Neurogenic cardiac effects of cerebrovascular diseaseCurrent Opinion in Neurology, 1994
- Spontaneous oscillations in cerebral blood flow velocity in normal humans and in patients with carotid artery diseaseNeuroscience Letters, 1991
- Transient changes in cerebral vascular resistance during the Valsalva maneuver in man.Stroke, 1984