Critikon, Inc

Josef K Tan

Jeffrey A Baker

John J George

Pawel J Beczkiewicz

A sensor for measuring the oxygen saturation of blood flow within the skull is described. In a first embodiment the sensor comprises a photodetector and a pair of light emitting diodes surface mounted near the end of a length of flexible printed wiring. The sensor is hermetically sealed by a coating of rubber or polymeric material which has an optical window over the photodetector and light emitting diodes. The sensor is inserted through a burr hole drilled in the skull and slides between the skull and the dura of the brain. The light emitting diodes are pulsed to illuminate blood within the dura and brain with light, and light reflected by the blood is received by the photodetector and converted to electrical signals. The signals are processed by a pulse oximeter to provide an indication of blood saturation. In a second embodiment the photodetector and light emitting diodes are mounted at the end of a core of compressible foam extending from the end of a hollow bone screw. As the bone screw is screwed into a burr hole in the skull the photodetector and light emitting diodes will contact the dura and the foam will compress to maintain optical contact between the electrical components and the dura. Light from the diodes is reflected by blood in the dura and brain, received by the photodetector, and the resultant electrical signals are processed by the pulse oximeter.

Epidural oxygen sensor

A sensor for measuring the oxygen availability of blood flow within the skull is described. In a first embodiment the sensor comprises a photodetector and a pair of light emitting diodes surface mounted near the end of a length of flexible printed wiring. The sensor is sealed by a coating of rubber or polymeric material which has an optical window over the photodetector and light emitting diodes. The sensor is inserted through a burr hole drilled in the skull and slides between the skull and the dura of the drain. The light emitting diodes are pulsed to illuminate blood flow in the brain beneath the dura with light, and light reflected by the blood is received by the photodetector and converted to electrical signals. The signals are processed by a pulse oximeter to provide an indication of blood availability. In a second embodiment the photodetector and light emitting diodes are mounted at the end of a core of compressible foam extending from the end of a hollow bone screw. As the bone screw is screwed into a burr hole in the skull the photodetector and light emitting diodes will contact the dura and the foam will compress to maintain optical contact between the electrical components and the dura. Light from the diodes is reflected by blood in the dura and brain, received by the photodetector, and the resultant electrical siganls are processed by the pulse oximeter.

A finger sensor for a pulse oximetry system is provided having a body of flexible, resilient polymeric material formed as a pocket. On the inside walls of the pocket toward the closed end are a LED light source and an opposing photodetector. The space within the pocket transverse to the longitudinal dimension of the pocket exhibits a relatively smaller width and a relatively greater width. As a finger is inserted into the pocket with the fingertip between the LED and the photodetector, the relatively smaller width of the pocket expands and the relatively greater width of the pocket decreases. This expansion and decrease of the pocket dimensions are resisted by the resilient polymeric material, causing the walls of the pocket containing the LED and the photodetector to securely contact and retain the finger within the pocket. The pocket preferably comprises a pocket having major walls containing the light source and photodetector adjoined on the longitudinal sides of the sensor by expansive side panels which expand and contract to engage fingers of varying sizes.

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Tampa, FL, United States of America

Josef K Tan