Abstract: A signal filter method and apparatus for removing portions of a signal indicative of erroneous data, an exemplary apparatus including means for receiving the signal, means for adjusting a threshold by increasing the threshold a first predetermined amount when the signal is in a predetermined relationship with the threshold and for decreasing the threshold a second predetermined amount when the signal is in a second predetermined relationship with the threshold, and means for comparing the signal with the adjusted threshold and for transmitting the signal if the signal bears a first predetermined relationship to the threshold. Disclosed herein are digital and analog implementations of the signal filter method and apparatus, particularly suited for use with catheter-type oximeter apparatus.

Abstract: An improved occulsion detection apparatus and method for use in a pumping apparatus wherein a motor control sequencer provides signals adapted to rotate the shaft of a motor and a pump mechanism through a pumping cycle. The motor is advantageouly initially operated at a first higher torque to insure proper starting of the pumping cycle and is subsequently operated at a second lower torque through the remainder of the pumping cycle, the motor stalling if an occlusion within a fluid delivery system causes the back pressure within the delivery system to exceed the torque capabilities of the motor. An occulsion detector times the pumping cycle and if the cycle exceeds a first predetermined time period, an occulsion alarm is generated. The occlusion detector may further cause the motor control sequencer to increase motor torque to attempt to complete the pumping cycle or may de-energize the motor after a second predetermined period to prevent damage to the pumping apparatus.

Abstract: Catheter apparatus having transmitting and receiving optical fibers for photometric analysis of a fluid eliminates the need for individually calibrating each catheter within a population of catheters by making substantially uniform the center-to-center spacing between the outlet aperture of each and every transmitting fiber and the inlet aperture of each and every receiving fiber of an individual catheter for all catheters within a population of catheters; and by making the size and shape of all the outlet apertures of all transmitting fibers generally uniform and the size and shape of the inlet apertures of all receiving fibers generally uniform in each catheter and from catheter to catheter and that the orientation of all transmitting fibers relative to all receiving fibers be similar.

Abstract: A device for precise metering of liquids for intravenous delivery to a patient and its method of use, the device including a pumping chamber with a reciprocable diaphragm positioned therein such that the cross-sectional area of the liquid flow path through this chamber is approximately equal to the cross-sectional area of the inlet and outlet of the chamber. The device also includes check valves positioned at the pumping chamber inlet and outlet and a gas retention chamber having an upper portion providing for the formation of the gas-liquid interface and a lower portion from which liquid free of gas bubbles may be removed.

Abstract: An optical scattering reference medium is formed of a plurality of scattering particles substantially uniformly dispersed in a substantially compliant, non-compressable transparent solid medium which is selectively positionable against the distal end of an optical catheter for use therewith within a sterilizable disposable package for performing repeatable photometric measurements to standardize the performance of the photometric measuring instrument.

Abstract: Catheter apparatus having transmitting and receiving optical fibers for photometric analysis of a fluid eliminates the need for individually calibrating each catheter within a population of catheters by making substantially uniform the center-to-center spacing between the outlet aperture of each and every transmitting fiber and the inlet aperture of each and every receiving fiber of an individual catheter for all catheters within a population of catheters; and by making the size and shape of all the outlet apertures of all transmitting fibers generally uniform and the size and shape of the inlet apertures of all receiving fibers generally uniform in each catheter and from catheter to catheter and that the orientation of all transmitting fibers relative to all receiving fibers be similar.