Baxter Travenol Laboratories, Inc.

Nick Zissimopoulos

William L Rudzena

Lee K Kulle

Thurman S Jess

Scott T Garrett

Vincent L Knigge

John Baron

In a flow metering apparatus a bubble detector for detecting bubble formation in tubing subject to deformation from internal fluid pressure includes a light source and a light detector. The light detector is positioned on the opposite side of the tubing from the light source such that the light transmitted through the tubing to the detector is dependent on the presence of fluid in the tubing and on the shape of the lumen of the tubing. A control circuit responsive to the output of the detector interrupts operation of the metering apparatus when the light transmitted through the tubing falls below a predetermined minimum level. False interruptions resulting from deformation of the tubing by pressure changes in the fluid are prevented by forming members which engage the wall of the tubing adjacent the light source and light detector.

Bubble detector

Improvements in infusion controlling apparatus used in limiting the flow rate of an intravenous solution to a patient. The improvements provide coarse and fine orientations of a casette through which the solution passes relative to a controller which valves the casette's inlet and outlet to provide measured volumes of fluid. The coarse alignment device includes spaced apart metal sections which grasp onto the casette and move it towards the controller's valving members. As the casette reaches the valving members, protuberances on the controller fit into indentations on the casette, as the fine adjustment. The indentations into which the protuberances fit form part of the casette's base section of plastic notwithstanding the location of a cover slip between these two items. The valving members couple to a rocker arm which pivots about a point located at its middle and has magnetic poles at its ends. The rocker arm's pivot point over the center leg of an E-frame electromagnet allows the arm to rotate between two orientations in which one of its magnetic poles contacts a side leg of the E-frame electromagnet. Current passing through a coil located on the center leg of the electromagnet moves the rocker arm between these positions, depending upon the current's direction. With no current in the coil, the arm's magnets and the E-frame provide a bistable magnetic device in which the rocker arm forces one of the valving members to close either the casette's inlet or its outlet. This prevents the uncontrolled passage of fluid through the casette to the patient.

Fluid-flow limiting apparatus for use with intravenous-solution

Valving configurations between the valve seat in a cassette and the valve members in a controller used to limit the flow rate of an intravenous solution to a patient. The configurations minimize the criticality of the alignment between the components. The cassette forms part of the flow path of the solution on its way to the recipient. The controller's valve member may stretch a membrane in the cassette and cause it to contact a flat surface surrounding the opening through which the fluid must flow. Alternately, the end of the valve member may be appreciably smaller than the opening, pass through it, and stretch the membrane until the latter contacts all of the opening's edge. The membrane meeting the edge of the opening in a closed loop prevents the flow of fluid through it. As a further possibility, the valve member may place the membrane in contact with one or more edges provided between two segments of a straight channel through which the solution flows.

Noncritically aligned valving devices for flow rate-limiting cassettes

Controller for an intravenous fluid delivery apparatus

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Schaumburg, IL, United States of America

Nick Zissimopoulos