Abstract: A system for monitoring intracranial pressure by an implantable cavity resonator unit and an associated externally located transceiver unit. The resonator unit includes a dielectric-filled cavity having a predetermined resonance frequency for high frequency electromagnetic waves. The cavity is bounded by a wall having a pair of intersecting slots forming a slot antenna and a deflectable diaphragm in communication with the interior of the cranium to deflect as a function of intracranial pressure. The deflection alters the resonance frequency of the cavity. The transceiver unit includes a linear wave guide having a pair of electrically conductive probes located in it. At least one of the probes is arranged to transmit an electromagnetic excitation wave from an associated transmitter through the slot antenna to cause the cavity to resonate at an altered resonance frequency, whereupon a resonance wave is reflected out of the cavity through the slot antenna.

Abstract: The guidewire attachment assembly comprises a tubing affixed to the proximal end of a guidewire. Inside the tubing is a shoulder and a ramp for directing and positioning a bolt arranged at the end of a resilient shaft affixed to the distal end of the extension wire. The assembly provides a positive locking action for the guidewire and extension wire and direct unlocking thereof.

Abstract: An indwelling catheter having an extremely low profile proximal section. The indwelling catheter of the present invention solves the problems associated with the prior art feeding catheters by providing an extremely low profile proximal section which is situated external to the patient's body when the catheter is in place. The external portion is preferably in the form of a "trap door", including a fiat base portion that lies against the patient's skin and a flat, hinged cover which is operative to seal the proximal opening of the catheter when not in use. In order to retain the catheter and prevent it from being accidentally dislodged, the catheter includes a series of helical coils which are unformed during catheter insertion and then automatically reform in order to hold the catheter in place internally. The catheter is self-adjusting in that fewer or greater loops will automatically reform depending upon the thickness of the patient's abdominal wall.