Cerebral hemodynamics during graded Valsalva maneuvers
نویسندگان
چکیده
منابع مشابه
Cerebral hemodynamics during graded Valsalva maneuvers
The Valsalva maneuver (VM) produces large and abrupt changes in mean arterial pressure (MAP) that challenge cerebral blood flow and oxygenation. We examined the effect of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation responses during (phases I-III) and following (phase IV) a VM. Healthy participants (n = 20 mean ± SD: 27 ± 7 years) completed 30 and 90% of...
متن کاملCritical closing pressure explains cerebral hemodynamics during the Valsalva maneuver.
The Valsalva maneuver (VM), a voluntary increase in intrathoracic pressure of approximately 40 mmHg, has been used to examine cerebral autoregulation (CA). During phase IV of the VM there are pronounced changes in mean arterial blood pressure (MABP), pulse interval, and cerebral blood flow (CBF), but the changes in CBF are of a much greater magnitude than those seen in MABP, a finding to date a...
متن کاملCerebral hemodynamics during the Valsalva maneuver: insights from ganglionic blockade.
BACKGROUND AND PURPOSE The aim of this study was to differentiate the mechanical effects of the Valsalva maneuver (VM) from the effects of changes in autonomic neural activity on cerebral hemodynamics in humans. METHODS Nine healthy subjects performed the VM before and after autonomic ganglionic blockade with trimethaphan. Blood pressure (BP) was measured in the radial artery with an indwelli...
متن کاملThe cerebrovascular response to graded Valsalva maneuvers while standing
The Valsalva maneuver (VM) produces large and abrupt increases in mean arterial pressure (MAP) at the onset of strain (Phase I), however, hypotension, sufficient to induce syncope, occurs upon VM release (phase III). We examined the effect of VM intensity and duration on middle cerebral artery blood velocity (MCAv) responses. Healthy men (n =10; mean ± SD: 26 ± 4 years) completed 30%, 60%, and ...
متن کاملCerebral versus systemic hemodynamics during graded orthostatic stress in humans.
BACKGROUND Orthostatic syncope is usually attributed to cerebral hypoperfusion secondary to systemic hemodynamic collapse. Recent research in patients with neurocardiogenic syncope has suggested that cerebral vasoconstriction may occur during orthostatic hypotension, compromising cerebral autoregulation and possibly contributing to the loss of consciousness. However, the regulation of cerebral ...
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ژورنال
عنوان ژورنال: Frontiers in Physiology
سال: 2014
ISSN: 1664-042X
DOI: 10.3389/fphys.2014.00349