Abstract: A fluid infusion positive displacement pump includes a plunger driven by a stepping motor which is operated by a motor control system. The control system advances the plunger to expel liquid in a series of incremental steps at a user-set pumping rate and until a preset total dosage has been delivered with the pumping rate being determined by the waiting time between each step. In order to minimize shock to the patient, the pump is operated at a plurality of increasing fractional rates during the start of pumping and at a plurality of decreasing fractional rates at the termination of pumping with the user-set (maximum) pumping rate occurring between such fractional rate pumping periods.

Abstract: An optical module for coupling a fiberoptic catheter to a catheter oximeter processing apparatus. The optical module includes a plurality of light emitting diodes, each of which is mounted on a flat surface at the free end portion of a respective bracket. A plurality of optical fibers, which are adapted to be optically connected to the catheter, have their free ends secured to a mounting substrate in spaced positions and in closely spaced alignment with the diodes. The diodes are each individually provided with electrical connections that can be selectively actuated by the processing apparatus. The brackets, which are fixed at one end, are constructed of thin flexible material so that the diodes can each be adjusted generally in the plane of the receiving end faces of the optical fibers so as to obtain maximum light energy transfer therebetween.

Abstract: An optical module couples a fiberoptic catheter to a catheter oximeter processing apparatus. The module includes a plurality of LED's for coupling the electrical control signals from the processor and converting them to light signals to transmit to the catheter. The module also includes the means to convert the received reflected light signals from the catheter to electrical signals to be transmitted to the processor. The module further includes a memory to store calibration signals and other data so that the module and catheter can be disconnected from the processor and used with a different processor without necessitating a recalibration.

Abstract: A calibrating device for an optical catheter is provided in order to calibrate the catheter for use in a catheter oximeter system. The calibrating device includes a tube having a reference block therein which is spring-loaded into compliant engagement with the distal end of the catheter carrying the fiberoptic light transmitting and receiving guides. A releasable strap tightly secures the catheter to the calibrating device. The packaged catheter is therefore ready for calibration by simply removing the proximal end thereof from a sealed package while the calibrating device and major length of the catheter remain in their sealed and sterilized condition and connecting it to a processor for performing the calibration operation.

Abstract: A surgical instrument includes a handle and a disposable assembly which can be readily replaced after each operation or as necessary. The disposable assembly includes both an electrically heated scalpel blade and an electrosurgical active electrode which are mounted in a spaced parallel arrangement so that they can be used alternately by rotating the instrument by 180 degrees. The mounted ends of both the blade and the electrode are adapted to be received by separate terminals in the instrument handle so that the appropriate external power sources can be selectively connected thereto.

Abstract: A fluid infusion pump driver device for pumping fluid from the chamber of a disposable cassette. The pump driver includes a reciprocatable plunger which is driven by a stepping motor. The motor and plunger are coupled through a universal joint which provides a threaded connection translating the incremental angular movements of the motor into incremental linear movements of the plunger, and the plunger is coupled directly to the frame through a flexible leaf spring to prevent wear in the threaded connection from generating undue noise or creating accuracy problems.

Abstract: An I.V. pump cassette includes an enclosed pumping chamber with an inlet and outlet adapted to be connected to I.V. tubing. A reciprocable plunger extends from the top of the pumping chamber. The cassette is arranged to be received in a semi-cylindrical chamber in a driver mechanism wherein a horizontally extending support portion of the cassette can be supported in a semi-circular recess and clamped thereon by overlying clamp members of the driver mechanism. An upstanding semi-circular fence is provided at the front end of the cassette to activate a laterally pivotable switch in the appropriate driver mechanism and to create an interference with the wall of the semi-cylindrical chamber in an inappropriate driver mechanism.

Abstract: A liquid flow regulator has a housing formed by two parts that snap together. The housing defines an axial bore, an inlet, an outlet and a plurality of axial grooves opening endwise of the inlet and laterally of the housing into the bore. The grooves taper axially so that the cross-sectional area of each groove gradually decreases from the inlet to nothing at a pont where the groove merges with the bore. The grooves have different axial lengths. An elastomeric sock fits within the bore. Means for expanding the sock radially outward into sealing engagement with the housing adjacent the bore is axially movable within the bore. Flow through the grooves and the bore is regulated by the axial position of the sock expanding means and the minimum cross-sectional area of the tapered, axial grooves at the axial location where the sock seals the bore. Axial adjustment of the sock expanding means sequentially opens and closes passage from the grooves through the bore to the bore outlet.

Abstract: A controller for regulating current flow through a resistive heating element in order to adjust the temperature thereof is disclosed. The controller includes a means for periodically measuring the resistance of the heating element. During controller calibration, the rate of change of the measured heating element resistance is ascertained in order to determine whether the heating element is at ambient temperature. Computations are performed on the value of the measured heating element resistance associated with ambient temperature conditions, enabling the controller to predict the value of the heating element resistance at a desired temperature. Current is then conducted through the heating element to generate heat, while periodic measurements of the heating element resistance are performed.

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: The controller of the present invention regulates the flow of current through a resistive heating element by computing the predicted resistance R.sub.hot of the heating element at the desired temperature and then adjusting the voltage drop across and current flow through the resistive heating element until the relationship V=IR.sub.hot is satisfied. In an analog embodiment of the present invention, measurement of the voltage drop is obtained from a voltage amplifying circuit connected across the resistive heating element, while a measure of the current flow through the resistive heating element is obtained from a current amplifying circuit connected across a current measuring resistor in series with the resistive heating element. The output of the current amplifying circuit is multiplied by first and second variable gain amplifier circuits to produce a signal output representing the product of the current flow and the predicted resistance at the desired temperature.

Abstract: A portable infusion device includes a disposable syringe which is located in a removable section of a compact package that comprises the device. In order to conserve space, a flexible piston rod assembly is provided wherein the syringe plunger head is connected to a thin flexible plunger stem which is reversely bent about the upstream end of the syringe body so that the outer end of the stem lies directly adjacent and parallel to the syringe body. A small motor located in the non-removable portion of the package drives the plunger through a screw which sequentially engages closely spaced teeth on the face of the plunger stem as it moves along the outer surface of the syringe. When the syringe contents have been discharged, the removable section, including the syringe and plunger stem assembly, can be readily removed and replaced.

Abstract: The cutting instrument of this invention is adapted to be heated to a predetermined temperature range and includes a steel substrate having a cutting edge, a copper composition having a yield strength of at least 25,000 p.s.i. laminated to the steel substrate and an electrical heater means secured to the copper composition laminate. The cutting edge of the cutting instrument and at least a part of the copper composition and heater means may be coated with a non-stick composition in order to prevent the cutting instrument from sticking to the subject upon which the cutting operation is performed with the cutting instrument.

Abstract: The cutting instrument of this invention is made by threading a heater assembly through a hollow cutting instrument body. A blade having a shank and a blade body including a cutting edge is secured within the hollow cutting instrument body at its shank portion such that the blade body extends from the hollow cutting instrument body. The heating assembly is secured to the blade body and to the cutting instrument body. The blade body is coated with a non-stick means.

Abstract: A control procedure for governing the incremental step operation of a pump stepping motor (74) employed in conjunction with a parenteral fluid metering device (2) is disclosed. The control procedure enables fluid to be pumped from the metering device (2) in non-pulsatile, essentially continuous fashion by suitably adjusting the stepping motor speed to compensate for the interruption of fluid flow which occurs during the refill phase (P.sub.R) of each pumping cycle (C). Adjustment of the stepping motor speed also compensates for non-linearities otherwise introduced into the fluid flow as a result of the camming mechanism (76,78) utilized to convert rotary stepping motor movement into rectilinear pumping movement.

Abstract: A microprocessor-based controller for regulating the operation of a fluid pump motor is disclosed, wherein the controller includes a protection circuit which prevents fluid over- or under-delivery conditions from occurring by shutting down the pump motor whenever the actual speed of the pump motor differs from a desired pump motor speed by more than a predetermined amount. A simulation means interconnected with the protection circuit simulates fluid over- or under-delivery conditions to test the accuracy of protection circuit operation.

Abstract: An optical connector for connecting photometric analysis equipment which includes a transmitting and receiving light pipe to a material such as flowing blood wherein the blood is not contaminated by the light pipe. The connector has a flow passage therethrough for connection to the blood flow conduit and a light pipe receiving passage extending at a right angle thereto. At the intersection of the passages there is provided an image transferring window, and the light pipe is arranged to be snugly received in the pipe receiving passage in abutment with the window. The image transferring properties of the window are such that no optical distortion occurs as light is transmitted from one face to the opposite face thereof. This is accomplished by forming the window of a coherent bundle of optical fibers of very small individual diameters in the order of 0.003 inches or less.

Abstract: An improved intravenous metering device (1a) having a measuring chamber (77) for use in measuring the discharge pressure of fluid exiting the device (1) is disclosed. The discharge pressure measuring chamber (77), which operates in conjunction with a pin (63) and flexure beam (65) arrangement to provide an indication of fluid discharge pressure, is incorporated into the fluid flow path through the device in order to permit sweeping of gas bubbles from the chamber (77) during device priming operations. Thus, complete removal of gas bubbles from the device (1a) prior to employing the device with a patient is more easily attainable.

Abstract: A device for precise metering of liquids for intravenous delivery to a patient, the device including a pumping chamber with a reciprocable diaphragm positioned therein. The device also includes check valves positioned at the pumping chamber inlet and outlet, and a gas retention chamber located upstream of the pumping chamber and having an upper portion providing for the formation of a gas-liquid interface and a lower portion from which liquid free of gas bubbles may be removed and directed into the pumping chamber.

Abstract: A device for precise metering of liquids for intravenous delivery to a patient, the device including a pumping chamber with a reciprocable diaphragm positioned therein. The device also includes valves positioned at the pumping chamber inlet and outlet, the valve at the pumping chamber inlet being operated independently of the pressure within the pumping chamber. The device also includes 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.