Cross-Frequency Coupling Between Cerebral Blood Flow Velocity and EEG in Ischemic Stroke Patients With Large Vessel Occlusion

Background: External counterpulsation (ECP) is a noninvasive method used to augment cerebral perfusion but the optimal use of ECP in ischemic stroke has not been well documented. We aim to investigate the effects of increasing ECP treatment pressure on cerebral blood flow and blood pressure (BP). Methods: We recruited 38 acute ischemic stroke patients with large artery occlusive disease and 20 healthy elderly. Mean cerebral blood flow velocities (CBFV) of bilateral middle cerebral artery were monitored using transcranial dopper. Continuous beat-to-beat BP was measured via finger cuffs. We started ECP treatment pressure from 150mmHg, then gradually increased to 187.5mmHg, 225mmHg and 262.5mmHg. CBFV and BP were recorded before ECP and during each pressure increment respectively for 3 minutes. CBFV data of patients was analyzed based on whether it was ipsilateral or contralateral to the infarct. Results: Median NIHSS of stroke patients was 5.5 and mean time after stroke onset was 5.24 days. Mean BP was significantly elevated from baseline in both groups after ECP started. BP increase percentages of two groups similarly kept augmented following raised ECP pressure and reach maximium at 262.5mmHg (patients 16.9% vs. controls 16.52% compared with baseline). Under different ECP pressures, ipsilateral mean CBFV of stroke patients increased 5.15% (150mmHg), 4.35% (187.5mmHg), 4.55% (225mmHg) and 3.52% (262.5mmHg) from baseline. All were significantly higher than baseline but did not differ among different pressures. Contralateral mean CBFV changed likewise (5.16%, 4.02%, 3.7% and 3.34% increase from baseline). Mean CBFV of controls under ECP pressures did not increase from baseline. Conclusion: The increasing treatment pressure of external counterpulsation continuously augments blood pressure but not cerebral blood flow velocity of ischemic stroke patients with large artery occlusive disease. Cerebral blood flow velocity of stroke patients significantly increases from baseline under ECP pressure of 150mmHg but it reaches a plateau as ECP pressure further raises. Among 4 ECP pressures above, 150mmHg is the optimal treatment pressure for ischemic stroke due to higher risks of hypertension-related complications in acute stroke with higher ECP pressure.

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HOBOE (Head-of-Bed Optimization of Elevation) Study: Association of Higher Angle With Reduced Cerebral Blood Flow Velocity in Acute Ischemic Stroke

Physical Therapy ◽

10.2522/ptj.20100271 ◽

2011 ◽

Vol 91 (10) ◽

pp. 1503-1512 ◽

Cited By ~ 24

Author(s):

Abigail Jade Hunter ◽

Suzanne J. Snodgrass ◽

Debbie Quain ◽

Mark W. Parsons ◽

Christopher R. Levi

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Ischemic Stroke ◽

Flow Velocity ◽

Blood Flow Velocity ◽

Cerebral Blood Flow Velocity ◽

Mean Flow ◽

Study Association ◽

Blood Flow Velocities ◽

Flow Velocities

BackgroundCerebral autoregulation can be impaired after ischemic stroke, with potential adverse effects on cerebral blood flow during early rehabilitation.ObjectiveThe objective of this study was to assess changes in cerebral blood flow velocity with orthostatic variation at 24 hours after stroke.DesignThis investigation was an observational study comparing mean flow velocities (MFVs) at 30, 15, and 0 degrees of elevation of the head of the bed (HOB).MethodsEight participants underwent bilateral middle cerebral artery (MCA) transcranial Doppler monitoring during orthostatic variation at 24 hours after ischemic stroke. Computed tomography angiography separated participants into recanalized (artery completely reopened) and incompletely recanalized groups. Friedman tests were used to determine MFVs at the various HOB angles. Mann-Whitney U tests were used to compare the change in MFV (from 30° to 0°) between groups and between hemispheres within groups.ResultsFor stroke-affected MCAs in the incompletely recanalized group, MFVs differed at the various HOB angles (30°: median MFV=51.5 cm/s, interquartile range [IQR]=33.0 to 103.8; 15°: median MFV=55.5 cm/s, IQR=34.0 to 117.5; 0°: median MFV=85.0 cm/s, IQR=58.8 to 127.0); there were no significant differences for other MCAs. For stroke-affected MCAs in the incompletely recanalized group, MFVs increased with a change in the HOB angle from 30 degrees to 0 degrees by a median of 26.0 cm/s (IQR=21.3 to 35.3); there were no significant changes in the recanalized group (−3.5 cm/s, IQR=−12.3 to 0.8). The changes in MFV with a change in the HOB angle from 30 degrees to 0 degrees differed between hemispheres in the incompletely recanalized group but not in the recanalized group.LimitationsGeneralizability was limited by sample size.ConclusionsThe incompletely recanalized group showed changes in MFVs at various HOB angles, suggesting that cerebral blood flow in this group may be sensitive to orthostatic variation, whereas the recanalized group maintained stable blood flow velocities.

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