Abstract: A system detecting the presence of successive drops of fluid in a fluid path has a system input for connection to a photoelectric transducer so situated as to have a change in electrical output on the presence of a drop in the fluid drop path. The system includes an arrangement for storing a quantity related to the value of the photoelectric transducer output in the absence of a drop. The quantity stored can then be compared with the present value of the output of the photoelectric transducer, and in the event of a sufficient difference, an output may be provided. In a preferred embodiment, the output signal itself may be used to disconnect the storage system from receiving input information that pertains to the presence rather than the absence of a drop.

Abstract: An arrangement for improving the detection of drops in a drip chamber has a mirror element configured to focus light from a source to a detector in such a manner that a falling drop occludes a significant portion of the light reflected to the detector. In a preferred embodiment the mirror is located slightly below the drop forming orifice of the drip chamber and is shaped like an arcuate band of a curved surface. In a further preferred embodiment, a rotary motor with an eccentric weight is briefly energized to vibrationally clear any accumulation of droplets from the chamber wall. Other embodiments utilize a plurality of mirror elements to define an optical path from the source to detector which traverses the region throught which a drop falls 3 or more times.

Abstract: An infusion pump has a removable reservoir including a piston and drive member. The drive member is an internally threaded elongated portion of the piston. A motor rotates a short drive screw, which engages the threads of the drive member to displace the piston in the reservoir. In one embodiment the piston is attached to the drive member by a severable central stem which breaks away to allow engagement with the drive screw. With the stem severed, the piston cannot be retracted, or the reservoir refilled. Other safety features are shown for locking the displaced piston in the reservoir. A digital metering system has a safety circuit to prevent dangerous failure modes of the rotation sensor and motor drive systems.

Abstract: A modular clamp system in one embodiment has a case having an inlet and an outlet port, forming a housing for a resilient flow tube. Attached to the housing is a clamping member having two arms between which the flow tube passes. One end of the pair of arms fits within and is engaged by the hollow bore of threaded adjuster which is guided by the case. Turning the adjuster advances it, causing the arms to be pushed closer together, so as to progressively constrict the flow tube at a controllable rate. The arms may be tapered and the bore a right cylindrical bore, or the bore may be tapered and the arms untapered, in which case the tips of the arms contact with the interior face of the bore. The fineness of the screw threads and the degree of taper of the adjuster contacting surfaces may be so chosen that a full rotation of the adjuster causes a very small adjustment in flow rate.

Abstract: An intravenous flow control system includes a programmed microprocessor which receives information from a drop sensor and varies the adjustment of a clamp to control the infusion rate. The system accepts total dose and infusion duration, or dose rate and time information keyed in by the user, and periodically develops a target rate, based on the amount of infusate already delivered, such target rate being calculated to correct the actual delivered dose to that determined by the user keyed data. The target rate differs from the programmed rate by an amount equal to the programmed rate times an adjustment factor. In a preferred embodiment a series of tolerance bands corresponding to delivered volume errors are defined, with the adjustment factor a constant in each tolerance band. For high rate discrepancies, slewing is used to correct the clamp adjustment. Inability to attain the target rate before the delivery of a threshold volume of fluid triggers an alarm.

Abstract: A sheet with inlet and outlet ports forms a housing, with a flow tube disposed between the ports. In a preferred embodiment, a plurality of arms affixed at one end to the housing are adjustably spaced by a threaded tapered nut which mates with the other end of the arms. The flow tube passes between the arms and is constricted by the arms as the nut is advanced. The thread pitch, the degree of taper, and the point where the tube crosses the arms all determine the rate of constriction. In a further preferred embodiment the tube passes through a transverse indentation in the arms and is bonded thereto. In another preferred embodiment the housing is adapted to removably mount on an automatic flow sensing and adjusting module, which engages the tapered nut to adjust the flow rate through the tube.

Abstract: In a system for controlling fluid flow from a reservoir to a patient, a first signal representative of reservoir weight and a second signal representative of desired weight are compared digitally to generate a signal representative of their dissimilarity. An analog strain gauge may be used together with an analog-to-digital converter for generating the reservoir weight signal.

Abstract: A unitary sheet device for removably securing a catheter to the skin of a patient includes a pair of flaps for being affixed to the skin and a central portion performed in a contour conforming to the catheter hub. When affixed, the central portion and the patient's skin together form a receptacle for securely holding the catheter against movement. The central portion may be a tapered conical sheet and the flaps may have adhesive for ease of attachment. A detent is provided, which may include a hole through the central portion of the sheet for engaging a protrusion from the catheter hub. Flexing of the sheet disengages the detent. A non-adhesive tab on one flap aids in removing the device.

Abstract: A device for reducing the rate of flow from a reservoir as the reservoir empties requires only a single chamber having an input, for receiving fluid from a reservoir, and an output port. There is a provision for sensing fluid level in the chamber, and a separate provision for reducing the flow through the output port when fluid level in the chamber has fallen to a predetermined level. In a preferred embodiment of the invention, fluid level is sensed by a float, which, after falling to a predetermined level, actuates a plunger that reduces flow through an aperature at the bottom of the chamber.

Abstract: In a fluid flow control system a weight detector generates a signal representative of the weight of the fluid in the reservoir. A second signal is generated indicative of the desired fluid weight over time, and a first comparator produces an output indicative of the dissimilarity of the two signals. A programmed drop rate signal is modified by the first comparator's output to produce a desired drop rate signal. A drop detector produces a signal indicative of the actual drop rate. A second comparator is operative upon the desired drop rate signal and the actual drop rate signal to produce an output for operating the flow controller.

Abstract: In a system for controlling flow of fluid from a reservoir to be delivered intravenously to a patient, a valve adjustably constricts a fluid path and maintains a given adjustment until the adjustment is changed. In a preferred embodiment, a valve assembly is insertable into a servo assembly that controls flow through the valve. The valve can be removed from the servo assembly and, when so removed, will retain its last adjustment. A preferred embodiment of the valve utilizes a screw to compress a tube of resilient material.