Abstract: A system for detecting an occlusion in a fluid line is disclosed which can detect occlusions in the downstream or patient side of a disposable cassette containing a fluid pump thereon. The cassette includes a pressure diaphragm and is for installation onto and use with a main pump unit including a pressure transducer therein for monitoring fluid pressure downstream of the pump. The system utilizes control circuitry to provide an alarm in the event of a patient-side occlusion, and the occlusion detection system works when the system is configured as any of a number of difference device types, including both a flow controller emulation and several different infusion pump configurations.

Abstract: A pressure diaphragm installed in a disposable cassette for use on a main pump unit is disclosed which allows pressure downstream of a fluid pump to be measured with a high degree of accuracy. The pressure diaphragm is located over a raised cylindrical pressure plateau, and is spaced away from the plateau on the top and on the sides thereof to allow for a free movement of the pressure diaphragm. Fluid flow is from one side of the pressure plateau to the opposite side, with fluid flowing between the pressure diaphragm and the top and sides of the pressure plateau, as well as through a channel disposed in the pressure plateau.

Abstract: In a first embodiment, hysteresis is provided in a rate-responsive pacemaker to allow for natural AV synchrony when possible. In the absence of natural SA node signals, the heart is stimulated at a rate determined by the sensing of physiological need. When a natural heart signal is detected, the hysteresis is activated to extend the escape interval by a predetermined amount which is related to the sensed physiological need. The stimulating pulses are inhibited as long as normal heart activity is sensed. The extension of the escape interval under such conditions eliminates possible competition between normal activity and the paced stimulation. In a second embodiment automatic mode switching is provided in a dual chamber pacemaker to allow for more efficient operation at higher heart rates. When the heart rate (natural or paced) exceeds a prescribed level, such as 90 beats per minute, the pacemaker operates in a single chamber mode, such as VVI.

Abstract: A multiple channel medication infusion system is disclosed which has a plurality of disposable pump cassettes mounted on a single main pump unit, thereby making the system compact and resulting in an economic system. The system has a printer which may be connected to the main pump unit to provide a printed record of system operation. Several modes are accessible to set up and program the system, to monitor actual system performance, and to test the system or display warnings indicating system malfunctions or that new cassettes should be installed.

Abstract: A mechanical drive system for use in driving a disposable cassette containing a reciprocating fluid pump and active valves from a main pump unit is disclosed which utilizes a single power module cam to drive both the reciprocating pump and the valves. By using a unitary power module cam, the system completely eliminates the possibility of a timing error between the operation of the reciprocating pump and the valves. A one-way clutch is used to prevent the system from slipping into a reverse operation, and the operation of the valve actuators prevents the possibility of free flow through a cassette installed onto the main pump unit.

Abstract: A pacemaker connector system for the coaxial heart lead of a bipolar pacemaker consists of two connector block assemblies housing circular springs which circumferentially grip the central and outer terminals of the lead. Protruding ends of the springs are covered by rubber septum buttons which, when depressed, open the spring interiors to allow insertion of the heart lead. The problems associated with set screw systems are eliminated, and improved mechanical and electrical contact over other types of spring systems is provided.

Abstract: A telemetry system for use with implantable medical devices is disclosed which utilizes both in-phase and quadrature data components, and frequency modulates both data components into a single transmitted sinusoidal signal which varies in frequency between two selected frequencies. The signal is received and decoded, preferably by a coherent decoder, into in-phase and quadrature components, which are then integrated and sampled to produce the two transmitted in-phase and quadrature data components, which may then be recombined to produce the transmitted data. The system requires only low power, and is capable of operating at a relatively high data rate while retaining a high degree of accuracy due to the splitting of the signal into the in-phase and quadrature data components.

Abstract: A high speed rotary filter device is disclosed which utilizes a shrouded rotor, the shroud located over the central bladed portion of the rotor minimizing secondary flow within the device and thereby enhancing the separation and removal of very small particles from the airstream passing through the device.

Abstract: A high speed rotary filter device is disclosed which utilizes a rotor having a bladeless portion between the inducer and the exducer portions of the rotor, thereby substantially eliminating secondary flow within the high speed rotary filter device.

Abstract: An improved clamp fixture is provided for supporting a medical instrument or the like in a selected orientation relative to a variety of different support structures, such as an upright pole, a tabletop edge, a bed rail, etc. The clamp fixture comprises an open-sided base bracket for receiving the selected support structure to extend through the base bracket along a first axis. A clamp screw is carried by the base bracket and is adjustable to securely retain the support structure against an inner support surface of the base bracket. A frame member is mounted on the base bracket for rotation generally about a second axis perpendicular to the first axis, with a spring-loaded lock pin releasably securing the frame member in one of several preset rotational positions. At least one frame arm extends outwardly from the frame member for connection to the medical instrument or the like in a manner permitting rotation of the medical instrument about a third axis perpendicular to the first and second axes.

Abstract: A test device for use with a pacemaker to simulate the load of a heart. The device is designed for telemetering control and includes in its circuit a magnetic reed switch which opens and closes a load circuit in response to a remotely applied magnetic field. The device is intended to be disposable and is installed in circuit with the pacemaker terminals which normally connect to the heart leads. The device as thus installed is packaged in the sterile shipping package with the pacemaker and both permit the final checking of the pacemaker within its sterile pack prior to shipment and testing of the pacemaker in preparation for implantation without the necessity of opening the sterile package to conduct the test.

Abstract: Circuitry for quantitatively determining the level of processed heart signals relative to actual sensing sensitivity level (threshold) in an implantable pacemaker. The measurement is useful for adjusting the settable threshold, polarity, filtering or amplification parameter settings for safe operation and noise rejection of the pacemaker.

Abstract: An implantable catheter for use in delivering insulin or other therapeutic fluids is disclosed which uses a novel terminator design to prevent the growth of fibrotic tissue from obstruction the catheter. The catheter takes advantage of fibrotic encapsulation by utilizing a depression in the surface of the terminator which will effectively keep fibrotic tissue spaced sufficiently away therefrom to allow fluid to be infused. In addition to being capable of long term implant, the catheter is implantable in the omentum, enabling the body's natural absorption of insulin to be successfully mimicked.

Abstract: Programmable timing and logic circuitry is provided to detect crosstalk between paced chambers of the heart and to provide compensation in the event crosstalk is detected. Signals sensed during a prescribed time window early in the cardiac cycle following an atrial pulse are presumed to be crosstalk. If crosstalk occurs, a shortened AV delay is triggered. If crosstalk does not occur, a programmed AV delay is maintained. Absent the occurrence of a ventricular event after the prescribed time window up to the end of the AV delay, a ventricular stimulation pulse is provided. If a ventricular event is sensed during this time, the ventricular stimulation pulse is inhibited.

Abstract: A system for determining P-wave or R-wave capture in response to pacemaker supplied electrical stimuli. One embodiment includes a conventional bipolar atrial lead having a tip electrode, connected to an atrial pulse generator circuit within an implantable pacemaker, and a ring electrode, spaced apart from the tip electrode, connected to a P-wave sensing EGM amplifier within the pacemaker. The bandpass characteristics of the P-wave sensing EGM amplifier allow detection of all electrical frequencies in the atrium within the bandpass chosen. The output signal from this amplifier is selectively telemetered to an external receiver, as is a signal indicating the generation of an atrial stimulation pulse, where the occurrence of atrial stimulation pulses and P-waves can be monitored. In operation, if constant time intervals between the monitored atrial stimulation pulses and P-wave occurrences are present, P-wave capture has occurred.

Abstract: A medication infusion system having a disposable cassette including a piston pump and active valves for installation on a main pump unit including a mechanical drive system for operating the cassette is disclosed which has a unique system for loading the cassette onto the main pump unit and latching the cassette in place on the main pump unit. The cassette includes a slide latch which closes the fluid path when the cassette is to be installed, the slide latch only being opened when the cassette is properly installed on the main pump unit with the valve actuators of the main pump unit preventing fluid freeflow. Latching the cassette in place causes a latch head on the main pump unit to grasp the piston on the cassette in a driving relationship.

Abstract: An implantable medical sensor (42) determines the oxygen content of blood. The sensor includes a miniaturized hybrid circuit (130) that includes light-emitting diode means (32), phototransistor means (34, 36), and a substrate (110) to which the light-emitting diode means and phototransistor means are bonded in a desired circuit configuration. The hybrid circuit is hermetically sealed within a cylindrical body (140) made from a material that is substantially transparent to light, such as glass. Feedthrough terminals (132, 134) provide means for making an electrical connection with the hybrid circuit. The light-emitting diode means is driven with a stair-stepped current pulse. In one embodiment, the sensor is embedded within a bilumen pacemaker lead (60) and positioned near the distal electrode (66) of the lead so that the sensor resides within the heart when the lead is implanted within a patient, thereby allowing the sensed oxygen content (MVO.sub.

Abstract: A power converter for use in converting a variable DC input voltage into a variable DC output voltage is disclosed which uses control circuitry on both the input and the output to optimize converter performance. By charging the inductor up nearly to the saturation point, but completely avoiding saturation of the inductor, power capability at the input end is maximized. By discharging the inductor completely without either losing power capability by continuing to attempt to discharge the inductor after the charge is depleted or by failing to nearly discharge the inductor thereby presenting the possibility of saturation to the boosting of current through the inductor during the next charge cycle.

Abstract: An analyzer-programmer system (30) for use with an implantable medical device, such as a cardiac pacemaker (20). The system facilitates non-invasive communications with the implantable device and makes analysis of the operation of the implantable device easier to understand and perform. The system includes conventional processor means (42) for processing a sequence of stored instructions stored in programmable read-only memory, or ROM (40). The ROM, although designed to be accessed through predefined page of information, and blocks within such pages, is configured to allow in-page addressing within any of a plurality of pages in a linear fashion. Programmed intervals to be sent to the implantable device are displayed by the system in tabular form or as scaled time-lines or bars (FIG. 9A), with each separate interval beginning and ending in proper timed sequence, thereby providing a prediction of the expected performance. Such programmed intervals can overlay or sidelay measured performance (FIG.