Cerebral hemodynamics during graded Valsalva maneuvers

Area of Science:

• Physiology
• Neuroscience
• Cardiovascular Science

Background:

• The Valsalva maneuver (VM) induces substantial, rapid alterations in mean arterial pressure (MAP), impacting cerebral blood flow and oxygenation.
• Understanding the intensity-dependent effects of VM on cerebral hemodynamics is crucial for assessing cerebrovascular health.

Purpose of the Study:

• To investigate the influence of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation.
• To analyze cerebral hemodynamic responses during and after varying intensities of the VM.

Main Methods:

• Twenty healthy participants performed 30% and 90% maximal VM while standing.
• Beat-to-beat measurements of MCAv, cortical oxygenation (using NIRS), and MAP were recorded.
• Data were analyzed across different phases of the VM relative to baseline.

Main Results:

• Significant interactions between VM phase and intensity were observed for MCAv, total oxygenation index (TOI), and MAP.
• MCAv and TOI decreased during phases II and III, with greater reductions at 90% VM intensity.
• Phase IV demonstrated a reactive hyperemia, with increased MCAv, MAP, and TOI, while cerebral autoregulation was least effective.

Conclusions:

• Intense Valsalva maneuvers profoundly affect cerebral hemodynamics.
• Modest cerebral ischemia during VM phases II-III is followed by reactive hyperemia in phase IV.
• Cerebral autoregulation is impaired during the recovery phase (IV) post-VM.