Abstract: An I.V. catheter is described, including a catheter and hub assembly and a needle and hub assembly. A needle guard, including a tubular distal portion and a split proximal flange, is located about the needle at the distal end of the needle hub. The needle includes a slot near the needle tip. As the needle assembly is withdrawn from the catheter, the needle guard slides along the needle until the split flange engages the needle slot, which locks the tubular distal portion of the guard over the needle tip.

Abstract: A dual source parenteral infusion system includes a primary controller which controls the flow rate of a parenteral solution, a display which displays parameters associated with the delivery of a primary solution, and pushbuttons for entering solution delivery parameters into the controller. The primary controller communicates with a secondary infusion module which is programmed to deliver solution from a secondary source, with the flow rate being controlled by the primary controller. The secondary infusion module includes a display for displaying parameters associated with the delivery of the secondary solution and a drop detector, and mounts about a drip chamber for the secondary solution. The module may also include pushbuttons for entering fluid delivery parameters for the secondary solution into the module.

Abstract: A flash plug for an I.V. catheter is formed of a body of polymeric material, and has a narrow distal end for insertion within a catheter flash chamber and a larger proximal end which extends from the flash chamber. The flash plug has an aperture extending through it from the distal to the proximal end. An insert of a porous material is located within the aperture, and is capable of passing air and blocking the flow of blood. The catheter body is compatible with flash chamber material so as to remain securely located within the flash chamber and provides protection for the insert. The aperture diameter is sized to retain the porous insert securely within the flash plug body.

Abstract: A catheter assembly is provided to facilitate taping of the emplaced catheter onto the patient's body. The assembly comprises a catheter extending distally from a catheter hub. The hub has a hub axis co-axially aligned with the catheter and provided with a pair of opposed wings integral with the hub. Each of the wings having a proximal edge and a distal edge are such that a portion of at least one of these edges forms an acute angle with the axis of the hub of from about 35.degree. to about 55.degree. whereby the taping operation of the wings to the patient's body may be facilitated.

Abstract: A pump control system is described in which the pumping mechanism causes corresponding movement of a pair of capacitor plates. The plates are energized by an a.c. signal, and the signal produced by the plates is amplitude detected, with the amplitude modulation representing pumping force. The pumping force is converted to pumping pressure. The pumping pressure peak during pumping and the pressure minimum during filling are detected to determine the portion of a pumping cycle required to make the transition between these two pressure levels. The difference between the two pressure levels divided by the transition portion of the pumping cycle gives a measure of the compliance of the pump chamber. The ratio of the compliance measure to the total cycle, when multiplied by the nominal chamber volume, gives a measure of unpumped volume, which is subtracted from the nominal volume to give the volume actually pumped during a pump cycle.

Abstract: A pulse oximeter is provided including two light emitting diodes. Each LED is energized by a unique modulation signal. Light produced by the LEDs passes through the tissue of a subject and is detected by a photodiode. The photodiode signal is separated by tuned circuits resonant at the two modulation signal frequencies and physiological information signals are recovered from the separated signals by amplitude demodulation. The inventive arrangement provides identification of back-to-back coupled LEDs and narrow band filtering for good noise immunity.

Abstract: A disposable diaphragm pump cassette comprises a flexible diaphragm member comprising hinged, rigid plates hingingly mounted on an inflexible plate and opposed to a pumping chamber surface to form a pumping chamber. The pump includes check valve means comprising movable circular plates integrally connected with the inflexible plate by flexible, extendable webs. The flexible diaphragm member comprises at least three inflexible diaphragm plates with edges in a common plane, each diaphragm plate having at least two straight diaphragm plate hinge edges. Each diaphragm plate hinge edge is adjacent to and aligned with a second diaphragm plate hinge edge of an adjacent diaphragm plate. The adjacent edges of each diaphragm plate hinge edge and second diaphragm plate hinge edge are attached together by a flexible hinge strip.

Abstract: A parenteral solution container spike is provided which accesses a solution container with a pointed end, provides means for attaching a drip chamber at the other end with a drop former extending from the spike into the drip chamber, and an annular projection extending outward from the drip chamber end of the spike for attaching to a droplet detector with the drip chamber properly positioned in the droplet detector.

Abstract: An improved over-the-needle catheter assembly is provided with means for facilitating one-handed separation of the catheter hub from the needle hub. The improvement comprises providing the catheter with a top outside surface presenting a generally smooth surface interrupted by a depression. The depression has a bearing wall for transmitting a force component applied by the finger of a user; such force component having a distal, coaxial direction with respect to the catheter hub.

Abstract: 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.

Abstract: A pulse oximetry system is provided in which LEDs of two different wavelengths illuminate tissue containing arterial blood flow. A photodiode receives light from the LEDs and produces electrical signals containing pulsatile components. The components of the two wavelengths are separated and the pulsatile waveforms are monitored until signal peaks are detected at the end of diastole. The waveforms are then integrated over the systolic interval, and the integrals are combined with the signal peak values to determine an index value. The index value is used to select a value representative of oxygen saturation from a look-up table.

Abstract: A communication protocol is provided to enable one of a number of transmitters using a common transmission line to independently gain exclusive use of the line. Before transmitting data, a transmitter first monitors the line to establish that it is idle. If it is, the transmitter then asserts the line for an interval unique to that given device. Thereafter the transmitter monitors the device momentarily to determine that no other transmitter is asserting the line and, if so, the transmitter may then gain exclusive control of the line.

Abstract: A back pressure sensor for a positive displacement pump comprises at least one flexible beam having a pivot end and a drive connector end, and a pump actuator mounted between the pivot end and the drive connector end. The pump actuator connects with a positive displacement member of a pump. At least one sensor beam is connected to the flexible beam at a mounting position between the distal end and vibration damping end thereof. A first capacitor plate is mounted on the flexible beam at a position adjacent to the pivot end thereof, and a second capacitor plate is mounted adjacent the distal end of the sensor beam in a position facing the first capacitor plate at a distance which permits a capacitance coupling between the capacitor plates. A vibration damping mass is secured to the vibration damping end of the sensor beam for damping drive motion vibrations in the sensor beam.

Abstract: A back pressure sensor comprising a flexible beam having a pivot end with a pivot pin and a drive connector end with a means for engaging a pump drive. A pump actuator is connected to the flexible beam at a position intermediate the ends and connects with a positive displacement pumping member. A sensor beam is attached to the flexible beam at a connecting point spaced from said pivot end. A first capacitor plate is mounted on the flexible beam at a point which is spaced from the connecting point. A second capacitor plate is mounted on the sensor beam in a position facing and spaced apart from the first capacitor plate at a distance therefrom which permits formation of a capacitance coupling therebetween.

Abstract: A disposable diaphragm pump cassette comprises a flexible diaphragm member comprising hinged, rigid plates hingingly mounted on an inflexible plate and opposed to a pumping chamber surface to form a pumping chamber. The pump includes check valve means comprising movable circular plates integrally connected with the inflexible plate by flexible, extendable webs. The flexible diaphragm member comprises at least three inflexible diaphragm plates with edges in a common plane, each diaphragm plate having at least two straight diaphragm plate hinge edges. Each diaphragm plate hinge edge is adjacent to and aligned with a second diaphragm plate hinge edge of an adjacent diaphragm plate. The adjacent edges of each diaphragm plate hinge edge and second diaphragm plate hinge edge are attached together by a flexible hinge strip.

Abstract: A hinged plate diaphragm pump comprising a pumping chamber defined by an inflexible member and a flexible member opposed thereto. The flexible member has at least three inflexible plates with edges in a common plane. Each plate has at least two straight plate hinge edges, each plate hinge edge being adjacent to and aligned with a second plate hinge edge of an adjacent plate, the adjacent edges of each plate hinge edge and second plate hinge edge is attached together by a flexible hinge strip. Preferably, the plates comprise at least one array of plates positioned about an axial center of symmetry perpendicular to the common plane. The hinged plates can be hingedly connected to a surrounding support plate and an axially central plate positioned at the axis of symmetry.

Abstract: A blood pressure cuff is applied about a subject's artery, and inflated above the systolic level thus fully occluding the artery for a full heart cycle. The cuff pressure is thereafter reduced to permit an increasing flow through the progressively less occluded artery, and a measure of the peak amplitudes of the successively encountered blood flow (oscillatory complex) pulses stored in memory. Also retained is the cuff pressure obtaining for each stored complex peak. In accordance with varying aspects of the present invention, the stored complex peak-representing data ensemble is corrected for aberrations; and improved data processing operates on the stored (and advantageously corrected) pulse peak data and the corresponding cuff pressure information to determine the subject's mean arterial blood pressure.

Abstract: A dual parenteral solution apparatus for delivering predetermined volumes of two solutions at predetermined flow rates with increased accuracy. The apparatus has a shut-off valve in the supplementary solution supply system which is immediately activated when the supplemental solution supply is depleted.