Patent ID: 8394025

Claim:
An apparatus for non-invasively determining the absolute value of intracranial pressure of a living body comprising: a Doppler device for noninvasively sensing blood flow in an ophthalmic artery extending from inside the cranium into an eye of the living body; a steering device for electronically directing ultrasonic pulses generated by said Doppler device at a plurality of depths and a plurality of steering angles in a plurality of planes passing through a central axis of said Doppler device; said Doppler device being adapted to receive said ultrasonic pulses from said plurality of depths and said plurality of steering angles in said plurality of planes passing through a central axis of the Doppler device and generate a Doppler signal representative thereof; a scan-mode processing unit adapted to receive said Doppler signal and noninvasively locate an intracranial segment of said ophthalmic artery and an extracranial segment of said ophthalmic artery; said scan-mode processing unit further adapted to select an intracranial steering parameter representative of a steering angle and a depth corresponding to said intracranial segment of the ophthalmic artery and select an extracranial steering parameter representative of a steering angle and a depth corresponding to said extracranial segment of the ophthalmic artery and generate an intracranial steering vector and an extracranial steering vector from said intracranial steering parameter and extracranial steering parameter, respectively; a multiplexer for directing said ultrasonic pulses in an alternating fashion at said intracranial segment of the ophthalmic artery and said extracranial segment of the ophthalmic artery according to said intracranial steering vector and said extracranial steering vector, respectively; a spectral-mode processing unit adapted to concurrently generate intracranial velocity and extracranial velocity signals representative of measured velocities of blood flow in the intracranial segment and extracranial segment, respectively, of the ophthalmic artery; a device for applying an external pressure against said eye and measuring and storing the applied external pressure; a processor adapted to calculate intracranial and extracranial angle-independent blood flow factors from said intracranial velocity signals and extracranial velocity signals and identify the absolute value of the intracranial pressure as that external pressure which causes the ratio of the intracranial angle-independent blood flow factor and the extracranial angle-independent blood flow factor to be equal to 1.