Abstract: A blood extraction and reinfusion flow control system includes a blood pump coupled to pump intravenous fluid to or from a subject, a pressure sensor coupled to sense extra veinous pressure at the subject, and a microprocessor based flow control subsystem. The flow control subsystem optimizes the flow rate by sensing pressure at at least two different fluid flow test points and extrapolating and translating the test point data to generate a flow control curve. The blood pump is then operated at a maximum speed that is limited by a desired maximum flow command and the flow control curve to maximize flow without vein collapse or damage during both blood extraction and reinfusion.

Abstract: A detector for automatically determining the presence of air in a fluid line comprises a plurality of ON-OFF optical sensors selectively disposed in series along the axis of a portion of an I.V. tube according to their relative light sensitivity and according to their dependence upon direct or refracted light for activation. An alarm condition indicates air-in-line when predetermined individual sensors change their ON or OFF condition in accordance with a microprocessor programmed logic sequence.

Abstract: For use independent of a stand, a monolithic, miniaturized gravity infusion regulating apparatus comprises a single casing (6) housing the photoelectric drop detector (7), the electronics with controls (8) and the regulating mechanism and which can be fitted to the drop chamber (1) of an infusion instrument (FIG. 2).

Abstract: The infusion of intravenous fluid into a patient is indirectly measured by monitoring the decreasing weight of an intravenous fluid receptacle as fluid flows from the receptacle to the patient. The method hereof includes the steps of taking a plurality of samples of the weight of the receptacle, calculating the difference between succeeding weight samples, comparing the weight difference against predetermined quality control criteria, taking additional samples if the criteria are not met, and converting the weight loss difference into volume of fluid infused into a patient. The apparatus hereof includes a transducer for sensing the weight of the fluid containing receptacle, circuitry for converting the analog signal generated by the transducer into a digital electronic electrical signal, and a processor for calculating the volume infused into a patient as a function of the sensed weight of the receptacle.

Abstract: An angiographic injector having a separable console selecting and displaying injector functions and parameters. Microprocessors provide serial data transmission between console and injector base, and between injector head and injector base. A microprocessor in the base controls the injector.

Abstract: An infusion system for infusing a flowable material into a patient comprising an infusion device for delivering the flowable material in both a normal delivery pattern and a test pulse and a conduit for conducting the flowable material from the infusion device to the patient. The test pulse creates a pressure wave response in the conduit. The pressure wave response is monitored and used to detect if the infiltration has occurred.

Abstract: Automatically monitoring the volume of blood removed from a patient during the arterial phase of a control cycle of single venipuncture needle apparatus, and switching from the arterial phase to the venous phase when a predetermined stroke volume has been achieved.

Abstract: A piggyback IV administration system uses a solenoid actuated sequence valve to control the flow of fluid from a pair of IV fluid sources to the inlet of an IV pump or controller. The sequence valve pinches off a first tube while allowing fluid to flow through the second tube and then, in response to a control signal, changes state so that the second tube is pinched off and fluid can flow through the first tube unimpeded. The sequence valve automatically senses conditions which indicate a failure of the sequence valve to occlude the second tube when the valve changes state.

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: The weight monitoring system provides a visual read-out to compare an actual weight change in a patient undergoing a change of weight treatment against the elapsed time of treatment. In one embodiment, the actual weight loss is displayed in bar form against the elapsed time also in bar form. In a second embodiment, the read-out uses a display screen for graphically displaying a chronological sequence of differences between a programmed weight change and an actual weight change.The monitoring system can be used to automatically control a dialysis unit or may provide readings which permit a manual adjustment in a dialysis unit.

Abstract: A medication infusion system provides redundant safety and includes condition detecting and informational alarm signal generating apparatus for indicating if (1) a fluid leak occurs in different portions of the system; (2) a programmable input from a patient or physician would result in exceeding a safe dosage limit; (3) the reservoir containing medication has been filled; (4) the intended medication pumping does not correlate with the pumping actually effected; (5) battery voltage is low; (6) the medication reserve is low; and (7) the system has been switched off. The apparatus may provide subcutaneous electrical, thermal, or audible stimulation to the patient and also provides a signal which a physician may monitor. The stimulation may be coded to separately identify each above-listed deviation in nominal system performance. In addition, the number of medication requests are correlated with actual medication dispensing to assure proper operation.

Abstract: A dual mode peristaltic device is provided for infusing I.V. solutions to a patient through an I.V. tube. In a first mode of operation, the device functions as a peristaltic pump and in the second mode of operation it functions like a controller. Included in the device and associated with the I.V. tube is a pressure sensing strain gauge assembly that monitors dimensional changes in the outer diameter of the I.V. tube as an indication of fluid pressure changes in the tube. The strain gauge assembly is positioned relative to the device's peristaltic means to alternately monitor fluid pressure in a patent I.V. tube upstream and downstream from the gauge assembly. In the first mode (pump mode), the device is programmed to alarm and cease operation when fluid pressure downstream from the gauge assembly reaches a preselected value.

Abstract: A bio-medical injector apparatus comprising a base unit having a skin engaging portion disposed at an angular orientation with respect to the longitudinal axis of the base unit for supporting and maintaining a hypodermic needle at an optimum angular orientation for effecting an injection procedure, a carriage assembly reciprocally mounted on the base unit and carrying the hypodermic needle simultaneously therewith, a motor drive unit operably connected with the hypodermic needle for the preloading thereof with a suitable medication, a solenoid secured to the base unit and operably connected with the carriage assembly for a controlled reciprocation thereof for effecting the injection operation of the needle, and an electronic circuitry operably connected between a power supply and the motor drive and the solenoid for creating the logic necessary to perform the functions of the injector apparatus.

Abstract: A flow rate sensing device, particularly for use in regulating the rate of flow in a system for parenteral administration of liquids to patients. The liquid emerges from a storage reservoir and is fed into a housing through an upstream flow passage portion and then is made to pass through a narrow throat passage wherein the velocity of the liquid increases while its pressure decreases. The liquid then emerges into a downstream flow through passage and flows through an outlet from the housing. In an intravenous fluid administration system, the housing outlet is connected to a terminal tubing section and an intravenous needle. A pressure transducer, consisting of two chambers separated by a resilient deformable diaphragm, has its upstream chamber in fluid and pressure communication with the upstream flow path portion and its downstream chamber in fluid and pressure communication with the flow emerging from the throat passage.

Abstract: A volumetric infusion actuator providing a slot means for receiving a valved cassette having exposed valve pads. An actuation means for automatically moving individual arms into and out of engagement with the valve pads according to a predetermined cycle which governs flow through the cassette.

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: In combination with a blood reservoir, a blood volume detecting apparatus is used to ensure safe operation of the reservoir which includes a conduit in fluid communication with a lower part of said blood reservoir, a diaphragm associated with the other end of the conduit and movable by a differential hydraulic pressure applied by the blood through the conduit, and means for detecting the swelling and contracting movement of the diaphragm.

Abstract: A blood flow system for processing blood has two phases of operation, an arterial phase and a venous phase. During the arterial phase, the system is filled with blood through operation of an arterial blood pump. When a predetermined blood pressure level in the system has been attained, the arterial blood pump is inactivated and a venous blood pump removes blood from the system for a given number of pump turns. By accurately monitoring both arterial and venous pumps operating cycles, ultrafiltration volume and rate may be determined.

Abstract: A continuous flow peritoneal dialysis system and process is disclosed which includes a source of sterilized peritoneal dialysis system in the form of a gravity feed head vessel (32). A by-pass valve (34) connects the head vessel to an inflow/outflow directional valve 40 which controls the inflow and outflow of the sterilized dialysis fluid to a peritoneal catheter (12). The peritoneal catheter is implanted into the peritoneal membrane (14) of the peritoneal cavity (15). A connectable/disconnectable inflow line (42) and outflow line (48) are connected to an inflow catheter (44) and outflow catheter (46), respectively, of the double peritoneal catheter (12). A pressure monitor (50) in the outflow line (48) monitors the pressure within the cavity (15) and adjusts the inflow and outflow accordingly to maintain a predetermined volume and pressure of dialysis fluid in the cavity to maintain the membrane (14) properly distended at all times for maximum dialysis efficiency and patient comfort.

Abstract: An IV fluid control system having an IV set and a control device (such as an IV controller or fusion pump) includes a flow sensor which senses the flow of fluid through the IV set. Fluid runaway is prevented by an interlock which prevents removal of the IV set from the control device unless the fluid flow through the IV set is stopped. As a result, the medical personnel must clamp the outlet tubing of the IV set to stop fluid flow before removing the IV set from the control device.

Abstract: The present invention provides an accurate method and apparatus for monitoring the drop flow rate from a fluid source. The drops are indirectly sensed by piezoelectric means mounted on a drip chamber when the drops impinge on a fluid surface in the chamber. The chamber can include a second differential piezoelectric sensing element, which provides a noise reference signal which can be subtracted from the drop sensing signal. The volume of the fluid drops sensed can be determined. The sensing element can be incorporated in open and closed loop disposable chamber modules which can include both monitoring and occlusion valving functions integral therewith.

Abstract: An air bubble detecting and discriminating circuit arrangement especially suitable for use in a peristaltic infusion pump assembly is disclosed herein. This arrangement not only detects air bubbles in the fluid flowing through the tubing forming part of the assembly, but distinguishes between those bubbles which are sufficiently large to create a problem and smaller, micro bubbles which need not be detected. The arrangement also automatically compensates for changes in the flow rate of the fluid through the pump assemblies tubing without requiring any modifications at the time the flow rate is changed.

Abstract: A pump-actuated sequencing valve for sequentially administering, to a patient, two fluids contained in separate respective reservoirs, wherein the fluid is pumped from a first one of the two reservoirs by means of a pump associated therewith. The valve comprises a first portion connected to the first reservoir, a second portion connected to the second reservoir, and a third portion connected between the first and second portions, on the one hand, and the patient, on the other hand. The second portion includes a ball valve which is pressure-responsive to operation of the pump for blocking flow of fluid to and from the second reservoir, thus blocking both forward flow from the second reservoir and backflow from the sequencing valve toward the second reservoir.

Abstract: A medical fluid injection system comprises a flexible conduit, a supply device, a movable element, and a blocking condition detection device. The supply device supplies a pressurized medical fluid through the flexible conduit. The movable element is moved for forcing the flexible conduit in a stressing direction to cause creep in the flexible conduit. The blocking condition detection device detects whether or not the flexible conduit is forced in an anti-stressing direction opposed to the stressing direction. In a specific form of the present invention, a monitor may be provided for monitoring whether the movable element is exactly moved or not.

Abstract: Bubble detecting infusion apparatus for infusing a liquid from a source into a patient through the lumen of a light transmissive conduit member, which lumen has a flat wall surface portion contacted by the liquid in the lumen, the conduit member having an operative position within a yoke in which it is removable disposed, the yoke having a light source for directing a light beam through the conduit member wall toward the flat lumen wall surface portion thereof and having a light sensor positioned to receive light from the source reflected through the conduit member wall by the flat lumen wall surface portion, the angularity between the incident light beam and the normal to the flat lumen wall surface portion being such that when a gas bubble is in contact with the lumen flat wall surface portion, substantially all light from the source incident thereon is reflected by said surface portion toward the light sensor, and when a bubble-free liquid is in contact with the lumen flat wall surface portion, said surfac

Abstract: A controller (34) is disclosed for use with a dual delivery system including a primary fluid container (12) and a secondary fluid container (14). The display (48) on the controller (34) presents a representation of the primary and secondary containers and prompts the operator to input the desired primary and secondary fluid flow rates and primary and secondary fluid volumes to be infused. During operation of the controller, a series of flow lines displays (118, 126, 144) represent motion of fluid from the container being drained to indicate to the operator which fluid is being infused. An alarm will be sounded upon the detection of an occlusion within the flow lines, the presence of air within the flow lines or an open door on the controller. During the flow from a particular container, the displays associated with the other container are deactivated to prevent confusion to the operator.

Abstract: An intravenous set is described which includes a housing which defines three separate chambers: an uppermost valve chamber, an intermediate volumetric chamber, and a lowermost drip chamber. The valve chamber is provided with an externally actuated structure for interrupting the flow of fluids into the volumetric chamber. In alternate embodiments, this valve member can include a magnetically responsive element, a diaphragm, or a pinch tube. A volumetric chamber is provided with a predetermined volume and is adapted for remote sensing of the fluid level inside the volumetric chamber. Fluids pass from the volumetric chamber into the drip chamber where they are formed into individual drops. The drip chamber is adapted to allow remote detection of drop formation and drop counting. A controller is described which, when used in conjunction with the described intravenous set, provides extremely accurately controlled rates of infusion.

Abstract: A monitor is described for use with an intravenous injection system of the type that includes an accumulator (18) located between the pump (14) and the needle (28) that connects to the patient's vein. The monitor generates an alarm when there is infiltration (no resistance to outflow, as when the needle withdraws from a vein) or occlusion (the needle is blocked). The monitor includes a pressure sensor (32) coupled to the accumulator, and a circuit (34) which responds to the rate of change of the pressure to operate an alarm when the rate of change exceeds a predetermined amount such as 5 mm Hg, but only when it exceeds that value over a particular time period such as 10 seconds or one minute.

Abstract: The present invention provides an accurate method and apparatus for sensing and monitoring any buildup in the downline tubing pressure in a fluid infusion system. The initial fluid pressure as indicated by the tubing location is sensed after a delay period and is utilized as a base pressure if it is within allowable limits. The infusion tubing location or pressure is then monitored and compared with the base location or pressure. The system will alarm if a preset differential location or pressure change is exceeded.

Abstract: A controller for an intravenous set is disclosed which operates both to maintain the instantaneous drip rate through a drip chamber included in the IV set at a desired value, and to modify this value repeatedly during the course of an infusion. The desired drip value is modified in accordance with the measured volumetric flow rate through the intravenous set such that if a particular infusion fluid produces abnormally small volume drops in the drip chamber, then the controller automatically increases the drip rate to compensate. In this way, extremely accurate control of the fluid flow rate is obtained without the need for complex infusion pumps. A disclosed embodiment operates to provide separate alarms for open line errors, air in line errors, and occlusion errors.

Abstract: An infusion control apparatus senses drops of an infusion liquid by way of a variation in the quantity of light received from a light source after the light passes through a drop chamber. When drops of the liquid are not sensed over a predetermined period of time, a cut-off operation for closing off an infusion liquid flow passage starts and takes priority over other forms of control. When a drop-wise flow of the liquid is sensed during the cut-off operation, the flow passage closing action is interrupted and a transition is made to resume control wherein the liquid drop interval is computed from an input signal based on the variation in received light, and the liquid flow passage is adjusted so that the drop interval is made to approach a set value.

Abstract: An infusion monitor for feeding liquids to patients which is light weight so that it may be easily hung on a liquid dripper and which is provided with means for pre-setting the volume infused and the rate of infusion. Means are also provided for automatically varying the rate of infusion, for automatically cutting-off the infusion and for sounding an alarm to alert an attendant if any variation from pre-set limits occur.

Abstract: A flow monitor including an optical sensing chamber and an electronic controller which allows determination of exact drop volumes and flow rates. In one embodiment, the flow monitor forms part of a gravity fed volumetric controller in an IV system. In another embodiment, the flow monitor takes the form of a urinary output monitor in a urine collection system. Basically, the flow monitor comprises a microcontroller which responds to parametric information fed into the system through a keyboard and variable information detected by a novel drop diameter detector. The electronic controller, in response to the parametric and variable information being fed into it, is able to determine the precise volume of IV solution or urine passing through the respective systems. In the volumetric controller, the microcontroller causes a linear actuator to control the diameter of a flexible pinch tube found in the IV system. Under one mode of operation, the diameter of the pinch tube is regulated to control drop size.

Abstract: A monitoring arrangement is provided for detecting for extreme pressure conditions in blood tubing lines of a hemodialysis system. The arrangement includes a first pushbutton switch and a pivoted lever arm. A clamping means is located at a first end of the lever arm for clamping the blood tubing line against the first pushbutton switch, and the other end of the lever arm opposes a second pushbutton switch. Under low pressure conditions, the blood pressure in the tubing is no longer sufficient to hold the first pushbutton switch closed. The switch then opens to signal a low pressure condition. Under high pressure conditions, the blood tubing pressure causes the lever arm to pivot so that the far end of the lever activates the second pushbutton switch, which signals a high pressure condition.

Abstract: An intravenous monitoring system in which dynamic reference threshold circuitry is used to provide output signals indicating the presence of liquid passing through the drip chamber of an intravenous feeding apparatus. A light sensor that detects the presence of liquid passing through the drip chamber generates a detecting signal that is amplified and processed by the dynamic reference threshold circuitry. The dynamic reference threshold circuitry comprises a comparator circuit, and a D.C. component reference circuit that provides the reference threshold to the comparator circuit. The amplified detecting signal is directed both to an input of the comparator circuit and the D.C. component reference circuit. The D.C. component reference circuit uses a diode to produce a voltage drop in the amplified detecting signal and an RC circuit to both store and emit a residual signal when there is a sudden drop in the amplified detecting signal.

Abstract: An infusion monitor for feeding liquids to patients which is light weight so that it may be easily hung on a liquid dripper and which is provided with means for pre-setting the volume infused and the rate of infusion. Means are also provided for automatically varying the rate of infusion, for automatically cutting-off the infusion and for sounding an alarm to alert an attendant if any variation from pre-set limits occur.

Abstract: An intravenous drip rate control device includes a control valve having horizontally oriented valve members each provided with valve elements arranged in interdigitating relation with respect to each other. A drip rate sensor senses each intravenous drip and produces an electrical signal in response to each drip. A microprocessor unit compares the sensed drip rate to a preset drip rate and controls operation of an actuating unit which causes one of the valve members to shift toward and away from the other valve member. When one of the valve members is shifted toward the other valve member, a horizontal portion of the drip tube is progressively stretched to narrow the opening through the stretched portion of the tube and thereby reduce the drip rate. When the valve member is shifted away from the other valve member, the tension on the stretched portion of the tube will be progressively released, thereby increasing the opening in the tube and increasing the drip rate.

Abstract: A two-pump single needle hemodialysis system is provided in which a flexible blood accumulator bag is located between the dialyzer and the second, venous blood pump. The accumulator bag is filled as the first, arterial blood pump is operated. Blood is pumped through the dialyzer and into the bag until the bag is full and taut. At this time, a rise in pressure is detected and the venous blood pump is activated to withdraw blood from the accumulator bag. The use of the accumulator bag assures that low blood pressures are maintained in the system.

Abstract: An intravenous monitoring system in which dynamic reference threshold circuitry is used to provide output signals indicating the presence of liquid passing through the drip chamber of an intravenous feeding apparatus. A light sensor that detects the presence of liquid passing through the drip chamber generates a detecting signal that is amplified and processed by the dynamic reference threshold circuitry. The dynamic reference threshold circuitry comprises a comparator circuit, and a D.C. component reference circuit that provides the reference threshold to the comparator circuit. The amplified detecting signal is directed both to an input of the comparator circuit and the D.C. component reference circuit. The D.C. component reference circuit uses a diode to produce a voltage drop in the amplified detecting signal and an RC circuit to both store and emit a residual signal when there is a sudden drop in the amplified detecting signal.

Abstract: A bubble detector system is provided which dynamically responds to changes in energy transmission efficiency. The output of a detector is coupled to a dynamic reference level circuit, which develops a reference level that changes slowly in a time-varying manner with changes in the energy level received by the detector. The output of the detector is also coupled to a bubble detector circuit which produces a detection signal that changes rapidly when gas is present between an energy source and the detector. The detection and reference levels are compared to detect the presence of gas in the flow of fluid between the energy source and the detector.

Abstract: The present invention provides an accurate method and apparatus for monitoring the drop flow rate from a fluid source. The method and apparatus allows for an intermittent drop flow rate by accumulating a weighted drop period rate error factor which is adjusted for each drop period detected.A drop period window is adjusted by each drop period and is utilized to determine if the current drop period is within the window indicating a normal operation. Drop periods outside the window cause a factor to be added to the accumulated error factor and drop periods within the window cause a factor to be subtracted from the accumulated error factor. This allows good periods to offset bad periods, so that minor fluctuations in the drop periods during normal operation can be ignored.

Abstract: In a method and apparatus for controlling the concentration of glucose in the blood stream of a subject at a desired level (BI) including controlling the supply of insulin (IR) by periodically measuring the blood glucose concentration (G) and selecting a predetermined basal infusion rate (RI) for the desired level, the step of selecting a predetermined basal infusion rate comprises periodically searching for the value of the basal infusion rate RI required for BI in accordance withRI=RI.sub.LAST (GY/BI)where (GY) is the present blood glucose level corrected to fit a least squares regression line, when the slope of the least squares regression line fit for the last five G values is less than 0.5 and GY is within .+-.50% of the desired BI level, and wherein the period between searches is equal to or greater than the period between glucose measurements.

Abstract: A computer-controlled medical care system for use in the treatment and diagnosis of patients provides for either automatic or manual control of a wide variety of medical procedures including diagnostic procedures. The system accepts modular vessel structures, each type of structure being adapted for carrying out a specific procedure and matching programs for carrying out the specific procedures. A microcomputer accepts a program which may be designed to fit the needs of a specific patient and which must watch the modular vessel structure. The microcomputer monitors the progress of the process and the physiological status of the patient and provides for the taking of appropriate steps should difficulties be encountered in carrying out the procedure. The system can also be programmed to analyze a fluid taken from an individual, to treat the fluid and return same to the individual and to schedule the infusion of appropriate medications.

Abstract: A combination load and latch mechanism for fluid flow control apparatus, wherein a latch mounted for pivotal movement may be manually opened to disengage an electromechanical manipulating device to permit loading or unloading a feeding tube, the latch automatically closing and the device re-engaging upon release of the latch. The latch includes a slotted side wall that defines a retaining surface for capturing the tube relative to the manipulating device, and a cam surface upon which the tube acts during loading to cam the latch open. Means are included for sensing movement of the latch prior to any disengagement of the manipulating device.

Abstract: A control system for an intravenous feed tube is provided that functions by sensing weight changes with respect to time, i.e., dw/dt, of an intravenous solution supplied to a patient, the solution being maintained as a free hanging load. The weight changes are detected by strain gauge sensors, and then applied as signals to a microprocessor that is programmed to produce suitable control responses. These responses are fed to a motor which applies a constrictive force to the intravenous tube and maintains the solution flow at the desired rate.

Abstract: Implantable variable flow infusion apparatus comprises a collapsible infusate chamber having an outlet conduit leading to the infusion site by way of series-connected fixed and variable fluid flow restrictors. The infusate in the chamber is maintained under substantially constant pressure by a nonelectric energy storage cell to establish flow from the chamber to the site. The variable restrictor is controlled by commands from a preprogrammed microprocessor and programmable memory powered by a small long-lived battery. The processor sets the variable restrictor to the proper setting to establish the correct infusate flow for the particular time of day. A pressure transducer connected across the fixed restrictor senses the pressure differential across the fixed restrictor which differential indicates actual infusate flow from the chamber.

Abstract: A programmable implantable infusion pump includes a housing containing a variable volume infusate chamber and variable volume control fluid pressure and displacement reservoirs. A conduit conducts infusate from the chamber exteriorly of the housing. A restricted fluid path exists between the two reservoirs which are filled with an incompressible control fluid. A loaded spring applies a constant force to the pressure reservoir causing fluid flow between the two reservoirs. The differential pressure across the flow restriction is sampled by a microprocessor which computes the fluid flow rate, that rate being proportional to the infusate flow rate from the chamber. When the fluid flow rate deviates from a programmed value, the processor issues an error command to a battery-driven motor which reloads the spring to reestablish the constant force on the pressure reservoir.

Abstract: A system for sensing flow faults in a membrane system for intravenous fluid introduction is provided. A scanner is pulsed to generate reflected energy signals representative of the position of a membrane within a chamber. The scanner is pulsed both before and after the membrane is commanded to move within the chamber. The signals are then compared by an electronic circuit to determine the difference between them. If there exists a sufficiently large difference between the signals, this indicates that the membrane is moving in response to the command signals and the system is functioning properly. If there exists little or no difference between the signals, this indicates that there is a flow fault in the system, and an alarm is sounded.

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: A drop sensing unit and associated, disposable drip chamber for dedicated use with the sensing unit in an IV fluid administration system, the sensing unit being adapted for convenient installation on and removal from the drip chamber, with cooperable engaging means on the sensing unit and chamber serving to locate and retain them in the desired relative position during use. Such engaging means provide for contact between the sensing unit and chamber at vertically spaced locations for effective retention, and are constructed and arranged to aid in preventing use of the sensing unit on drip chambers which differ from the specially designed chamber.