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Blood Volume Index (BVI)

Why Blood Volume Matters

The brain relies on cerebral autoregulation to maintain stable blood flow despite changes in blood pressure. To accomplish this, blood vessels continuously dilate and constrict, causing changes in cerebral blood volume.

 

These blood volume changes are the physiological mechanism that protects the brain from ischemia, edema, and secondary injury.

 

Because blood volume reflects vascular response to blood pressure, it provides a direct window into autoregulatory function.

What is Blood Volume Index (BVI)?

Blood Volume Index (BVI) is the world's first non-invasive measurement of cerebral blood volume.

 

Using the VO200 NeurOs sensor placed over the temporal lobe, BVI continuously measures changes in cerebral vascular volume caused by vasodilation and vasoconstriction.

 

Unlike traditional autoregulation monitoring methods that estimate blood volume indirectly through intracranial pressure (ICP), BVI directly measures the physiological parameter responsible for autoregulation.

Clinical Validation

BVI was validated against ultrasound measurements of vascular volume changes.

 

The study demonstrated strong agreement between BVI and ultrasound-derived vascular measurements, confirming that BVI accurately reflects changes in cerebral blood volume.

BVI Validation.png

Clinical Applications

  • Personalized Blood Pressure Management: Identify patient-specific blood pressure targets rather than relying on population-based MAP thresholds.

  • Neurocritical Care: Monitor cerebrovascular responsiveness following stroke or brain injury.

  • Cardiac Surgery: Guide blood pressure management before, during, and after cardiopulmonary bypass.

  • ECMO & Critical Care: Assess cerebrovascular function during hemodynamic instability.

Role in Personalized Blood Pressure Management

BVI provides direct insight into how cerebral blood vessels respond to changes in blood pressure.

 

By continuously monitoring cerebral blood volume, clinicians can identify the blood pressure range where autoregulation remains intact and cerebral blood flow is protected.

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