September 1, 1998Journal of Applied Physiology
Deterioration of cerebral autoregulation during orthostatic stress: insights from the frequency domain
Key result
Orthostatic stress via maximal lower body negative pressure significantly reduced steady-state cerebral blood flow velocity by 24% and mean arterial pressure by 9.4% (P < 0.05).
Why the study?
Does orthostatic stress induced by lower body negative pressure impair dynamic cerebral autoregulation in healthy subjects?
Population
12 healthy subjects
Comparison
Ramped maximal lower body negative pressure to… vs Baseline (rest)
Design
Other
Authors
Discussion
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Implication
Does not support practice change in patients; leaves open cerebral autoregulation's role in clinical presyncope.
Study Design
Type
Observational (n=12)
Structured PICO
Does orthostatic stress induced by lower body negative pressure impair dynamic cerebral autoregulation in healthy subjects?
P
Population
12 healthy subjects undergoing ramped maximal lower body negative pressure to presyncope to evaluate cerebral autoregulation.
E
Exposure
Ramped maximal lower body negative pressure (LBNP) to presyncope
C
Comparator
Baseline (rest)
O
Outcome
Changes in cerebral blood flow (CBF) velocity and mean arterial pressure (MAP), and their dynamic relationship (transfer function gain)surrogate
Main Result
p-value: p=<0.05
Orthostatic stress diminishes the damping effects of cerebral autoregulation on variations in cerebral blood flow velocity, which may contribute to the development of presyncope.
Cite This Study
Zhang et al. (1998) conducted an observational in Healthy subjects (n=12). Orthostatic stress (lower body negative pressure) vs. Baseline (rest) was evaluated on Change in cerebral blood flow velocity at maximal lower body negative pressure (p=<0.05). Orthostatic stress via maximal lower body negative pressure significantly reduced steady-state cerebral blood flow velocity by 24% and mean arterial pressure by 9.4% (P < 0.05).