TY - JOUR

T1 - Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation

AU - Larsen, F S

AU - Olsen, K S

AU - Hansen, B A

AU - Paulson, O B

AU - Knudsen, G M

PY - 1994/10

Y1 - 1994/10

N2 - BACKGROUND AND PURPOSE: This study validates transcranial Doppler sonography (TCD) for determination of the lower limit of cerebral blood flow (CBF) autoregulation and establishes a relation between global CBF and mean flow velocity (Vmean) in the middle cerebral artery.METHODS: Relative changes in CBF and in Vmean were compared in 12 normal volunteers (2 women and 10 men; median age, 30 years [range, 21 to 61 years]). Catheters was placed in the left radial artery and in the bulb of the right internal jugular vein, respectively. Baseline CBF was measured by single-photon emission computed tomography scanning; concomitantly, blood samples were drawn for calculation of the cerebral arteriovenous oxygen difference. Then changes in mean arterial pressure (MAP) were induced, and relative changes in global CBF were calculated according to Fick's principle assuming a constant cerebral oxygen metabolism. MAP was increased 30 mm Hg by norepinephrine infusion and was decreased by lower body negative pressure. Vmean was measured in the right middle cerebral artery by a 2-MHz probe, and blood samples were drawn at intervals of 5 mm Hg.RESULTS: MAP values between 122 (range, 110 to 140) and 48 (range, 34 to 75) mm Hg were measured. The lower limit of autoregulation (the blood pressure under which autoregulation is off) as determined by Vmean did not differ significantly from that determined by relative changes in global CBF: 91 (range, 41 to 108) and 79 (range, 53 to 113) mm Hg, respectively. A significant correlation between Vmean and relative changes in global CBF was demonstrated below the lower limit of autoregulation (R2 = .73, P < .001; CBF = -6.3 + 1.0.Vmean). Above the lower limit both values were stable.CONCLUSIONS: TCD is valid for determination of the lower limit of CBF autoregulation, and changes in CBF may be reliably evaluated by TCD during changes in cerebral perfusion pressure in normal subjects.

AB - BACKGROUND AND PURPOSE: This study validates transcranial Doppler sonography (TCD) for determination of the lower limit of cerebral blood flow (CBF) autoregulation and establishes a relation between global CBF and mean flow velocity (Vmean) in the middle cerebral artery.METHODS: Relative changes in CBF and in Vmean were compared in 12 normal volunteers (2 women and 10 men; median age, 30 years [range, 21 to 61 years]). Catheters was placed in the left radial artery and in the bulb of the right internal jugular vein, respectively. Baseline CBF was measured by single-photon emission computed tomography scanning; concomitantly, blood samples were drawn for calculation of the cerebral arteriovenous oxygen difference. Then changes in mean arterial pressure (MAP) were induced, and relative changes in global CBF were calculated according to Fick's principle assuming a constant cerebral oxygen metabolism. MAP was increased 30 mm Hg by norepinephrine infusion and was decreased by lower body negative pressure. Vmean was measured in the right middle cerebral artery by a 2-MHz probe, and blood samples were drawn at intervals of 5 mm Hg.RESULTS: MAP values between 122 (range, 110 to 140) and 48 (range, 34 to 75) mm Hg were measured. The lower limit of autoregulation (the blood pressure under which autoregulation is off) as determined by Vmean did not differ significantly from that determined by relative changes in global CBF: 91 (range, 41 to 108) and 79 (range, 53 to 113) mm Hg, respectively. A significant correlation between Vmean and relative changes in global CBF was demonstrated below the lower limit of autoregulation (R2 = .73, P < .001; CBF = -6.3 + 1.0.Vmean). Above the lower limit both values were stable.CONCLUSIONS: TCD is valid for determination of the lower limit of CBF autoregulation, and changes in CBF may be reliably evaluated by TCD during changes in cerebral perfusion pressure in normal subjects.

KW - Adult

KW - Blood Flow Velocity/drug effects

KW - Blood Pressure/drug effects

KW - Cerebral Arteries/diagnostic imaging

KW - Cerebrovascular Circulation/drug effects

KW - Female

KW - Homeostasis/drug effects

KW - Humans

KW - Labetalol/pharmacology

KW - Male

KW - Middle Aged

KW - Norepinephrine/pharmacology

KW - Regional Blood Flow/drug effects

KW - Trimethaphan/pharmacology

KW - Ultrasonography, Doppler, Transcranial

KW - Vascular Resistance/drug effects

U2 - 10.1161/01.str.25.10.1985

DO - 10.1161/01.str.25.10.1985

M3 - Journal article

C2 - 7916502

VL - 25

SP - 1985

EP - 1988

JO - Stroke

JF - Stroke

SN - 0039-2499

IS - 10

ER -