Abstract: A medical pump with a closed loop stroke feedback system and method, for use with a pumping chamber, for example in a cassette, is disclosed. The pump includes a pumping element that intermittently pressurizes a pumping chamber during a pumping cycle. A pressure sensor detects the pressure exerted by the pumping element on the pumping chamber. A position sensor detects the position of the pumping element. A processing unit processes pressure data from the pressure sensor and position data from the position sensor to determine a calculated stroke volume of the pump for a pump cycle, and to adjust a stroke frequency of the pump to compensate for variation in the stroke volume.

Abstract: A medical pump with an improved continuity low flow delivery system and method for use with a pumping chamber, for example in a cassette, is disclosed. The pump includes a pump drive for exerting a force on the pumping chamber and a sensor for sensing the force/pressure exerted by the pump drive on the pumping chamber. The pump drive position sensor senses the position of the pump drive. The medical pump also includes a processing unit and a memory having a programming code adapted to calculate the rate of change of the sensed force/pressure values and determine whether the rate of change of the sensed force/pressure values meets a rate of change threshold. Once the rate of change threshold is met, the programming code is adapted to calculate a remaining pump drive travel value for determining how much farther the pump drive should travel before the end of an effective pump cycle.

Abstract: A drive connector for elastomerically coupling a drive shaft to a driven shaft. An elastomeric coupling includes openings on opposite ends that are generally “D”-shaped forming an interference fit with correspondingly shaped ends of the drive shaft and the driven shaft. A web extends transversely within the interior of the elastomeric coupling, limiting the distance that the drive shaft and driven shaft are inserted within the openings of the coupling. The coupling includes a rib that runs longitudinally along its outer length. A sleeve having a groove corresponding in size and shape to the rib is slipped over the coupling and is connected to the driven shaft. The sleeve includes a rigid interior element that is overmolded with an elastomeric material. A cam bearing is fitted over a cam surface on the sleeve and provides a force in one direction, urging a plunger to displace an elastomeric membrane in a pumping cassette, forcing medicinal fluid to flow through the pumping cassette.

Abstract: A housing for a medicinal pump, which is sealed to prevent damage due to exposure of the housing to water or other liquids. The housing includes an extruded case in which the various components comprising the pump are enclosed. The ends of the extruded case are sealed by a top cap and a bottom cap that are overnolded with an elastomeric material. The elastomeric material seals the top and bottom caps against the extruded case and provides shock resistance to protect the pump from damage. An open side of the pump is sealed with a pump chassis that supports a pump cassette used to infuse medicinal fluids into a patient. A bezel assembly on the front surface of the pump is adhesively attached thereto using a double-sided adhesive sheet. The double sided adhesive sheet seals the openings for a display and a keypad formed in the front surface of the extruded case.

Abstract: In a pump chassis (112), spring-loaded members (108a, 108b) engage a pumping cassette (114) to it in a predetermined position. The members each include pairs of latches (110a, 110b) that are each beveled to form a ramp so that the latches and associated members are forced outwardly to enable the pumping cassette to be seated within the pump chassis. The latches engage the pump cassette as it is seated, holding it securely. A release button (138) is attached to a spring-loaded shaft (144) that extends into the interior of the pump chassis. The shaft has a ramp formed on its inner end. When the user depresses the release button, the ramp rides under inwardly extending arms (162a, 162b) provided on the members, forcing the members and attached latches to move outwardly. As the members move outwardly, the pumping cassette is released and readily removed.

Abstract: A system and a method for detecting the presence of air bubbles in an intravenous (IV) line supplying a medicinal liquid to a patient. An air bubble sensor includes an ultrasonic transmitter acoustically coupled to an ultrasonic receiver to detect the presence of a gas (e.g., air) in a portion of a tube comprising the IV line. The transmitter and receiver are mounted on pivoting transducers that are disposed on opposite sides of the tube. A spring biases the transducers inwardly toward each other so that the transmitter and receiver contact opposite sides of the tubing. This assembly automatically accommodates different sizes of tubing and tubing of a relatively wide range of stiffness. The tube is connected to a disposable pumping cassette that is engaged in a pump chassis on which the transducers are pivotally mounted.

Abstract: A cover for a battery compartment in a medical device such as an ambulatory pump that is used for infusing a medicinal fluid. The battery compartment cover includes a lever that is pivotal between an open and a closed position. The lever is connected to a plunger that applies a compressive force against an O-ring, which is trapped between a shoulder on a washer through which the plunger extends and an end of the plunger. When the lever is pivoted to its open position, the compressive force on the O-ring is released, enabling the battery compartment cover to be removed from the opening into the battery compartment. However, when the lever is pivoted to its closed position, it draws the plunger outwardly, applying a compressive force to the O-ring that causes the O-ring to expand radially outward, sealing the opening into the battery compartment against the intrusion of water or other liquids and securing the battery compartment cover in engagement with the opening.

Abstract: A system and a method for detecting the presence of an occlusion in an intravenous (IV) line supplying a medicinal liquid to a patient. Two pressure occlusion sensors are employed to produce a value for the proximal and distal pressures within an IV pumping cassette that is disposed in the fluid path of the IV line. Each pressure occlusion sensor includes a strain gauge connected to a leaf spring that is fixed at one end within a pump chassis and a rod that is disposed transverse to the leaf spring. Each rod has one end that responds to the force of a portion of an elastomeric membrane inside the pumping cassette and another end that contacts a free end of the leaf spring. When a leaf spring is flexed by the movement of a rod, the strain gauge mounted on the leaf spring produces a differential voltage that corresponds to a fluid pressure within the pumping cassette.

Abstract: A disposable pumping cassette having an integral auxiliary flow control and pressure monitoring member is used for delivering a medicinal fluid to a patient. The pumping cassette includes an elastomeric member mounted in a rigid body having an inlet and an outlet. An inlet valve and an outlet valve on the cassette are opened, and the flow control is positioned to allow the medicinal fluid to flow freely through the cassette, priming it before the outlet is connected to the patient. The cassette is then coupled to an associated pump driver, closing the flow control to disable free fluid flow through the cassette, and the outlet to the cassette is coupled in fluid communication with the patient's body.

Abstract: A modular ambulatory infusion pump comprises a base unit including an integral housing, said base unit including an infusion pump for infusing fluid into a patient's body, a battery power supply for energizing infusion pump and a control for operating the infusion pump to achieve at least one of a desired rate, a desired volume and a desired time interval for infusing the fluid. Disposed on the integral housing is a first electrical connector, said first electrical connector being provided to electrically couple the base unit to a mating connector on one of the plurality of modules, said one of the plurality of modules being coupled to the base unit to add a selected additional port to the base unit and to provide additional capability, said plurality of modules including a data port module that includes a printer interface port.

Abstract: A disposable pumping cassette having an integral auxiliary flow control and pressure monitoring member is used for delivering a medicinal fluid to a patient. The pumping cassette includes an elastomeric member mounted in a rigid body having an inlet and an outlet. An inlet valve and an outlet valve on the cassette are opened, and the flow control is positioned to allow the medicinal fluid to flow freely through the cassette, priming it before the outlet is connected to the patient. The cassette is then coupled to an associated pump driver, closing the flow control to disable free fluid flow through the cassette, and the outlet of the cassette is coupled in fluid communication with the patient's body. The medicinal fluid is drawn into a pumping chamber formed in the rigid body as a plunger of the associated pump driver is drawn up from the elastomeric membrane at a recess formed in the rigid body.

Abstract: A cam assembly and method for providing a substantially constant load to a motor that drives the cam assembly. A torque compensated cam assembly (142,300) includes a plurality of tracks (140,150,152/310,312,314) that are profiled with a surface that varies radially as the cam rotates, thereby actuating cam followers, each of which rolls along a different track. A tangential force developed by the cam followers as they move over rapid radial changes in the surfaces of the tracks produces a total net torque that at times tends to aid the rotation of the cam and at times tends to impede its rotation. In the application of the torque compensated cam assembly disclosed, the cam is used in a volumetric pump (30) that accurately delivers a desired volume of fluid at a desire rate. To assist in maintaining the accuracy of these parameters, the torque compensated cam assembly presents a substantially constant load to a motor (146,304) that drives the cam.

Abstract: A push button flow stop is mounted on a disposable infusion pumping cassette provided for use with a drug infusion pump. The flow stop is operative to enable or to block fluid flow through the cassette in a first mode and to monitor fluid pressure in the cassette in a second mode.

Abstract: A cam assembly and method for providing a substantially constant load to a motor that drives the cam assembly. A torque compensated cam assembly (142,300) includes a plurality of tracks (140,150,152/310,312,314) that are profiled with a surface that varies radially as the cam rotates, thereby actuating cam followers, each of which rolls along a different track. A tangential force developed by the cam followers as they move over rapid radial changes in the surfaces of the tracks produces a total net torque that at times tends to aid the rotation of the cam and at times tends to impede its rotation. The cam is used in a volumetric pump (30) that accurately delivers a desired volume of fluid at a desire rate. To assist in maintaining the accuracy of these parameters, the torque compensated cam assembly presents a substantially constant load to a motor (146,304) that drives the cam.

Abstract: A volumetric pump and method for displacing a predetermined quantity of fluid at a predefined cracking pressure, independent of supply and output pressures. The volumetric pump (30) includes an inlet cracking valve (46), an outlet cracking valve (52), and a plunger (48)for displacing fluid from a pumping portion (34b) of flexible tubing (34) that extends through the volumetric pump. The pumping portion of the flexible tube fills with liquid when the inlet cracking valve is fully opened and is urged to expand by jaws (236) on pivotally-mounted arms (234). The arms are forced to pivot, as tubing reshaper rollers (160), disposed on the plunger, roll along the inner surface (232) of each arm.

Abstract: A volumetric pump and method for displacing a predetermined quantity of fluid at a predefined cracking pressure, independent of supply and output pressures. The volumetric pump (30) includes an inlet cracking valve (46), an outlet cracking valve (52), and a plunger (48) for displacing fluid a pumping from a pumping portion (34b) of flexible tubing (34) that extends through the volumetric pump. The pumping portion of the flexible tube fills with liquid when the inlet cracking valve is fully opened and is urged to expand by jaws (236) on pivotally-mounted arms (234). The arms are forced to pivot, as tubing reshaper rollers (160), disposed on the plunger, roll along the inner surface (232) of each arm.

Abstract: A method for determining if fluid is being displaced by a volumetric pump. The volumetric pump (30) includes an inlet cracking valve (46) and an outlet cracking valve (52) disposed on opposite sides of a plunger (48) used to displace fluid by compressing flexible tubing (34). During a pumping segment of a pumping cycle for the volumetric pump, the outlet cracking valve is closed with a cracking force that compresses the flexible tubing until the pressure of the fluid displaced by the plunger exceeds a cracking pressure, at which time the outlet cracking valve opens to enable fluid flow from the volumetric pump. A cracking flexure (182) provides the cracking force. As the outlet cracking valve opens in response to the fluid pressure exceeding the cracking pressure, a flow detector (54) mounted to the cracking flexure responds to the stress generated in the cracking flexure thereby, producing a signal indicative of fluid flow from the volumetric pump.

Abstract: A volumetric pump and method for displacing a predetermined quantity of fluid at a predefined cracking pressure, independent of supply and output pressures. The volumetric pump (30) includes an inlet cracking valve (46), an outlet cracking valve (52), and a plunger (48) for displacing fluid from a pumping portion (34b) of flexible tubing (34) that extends through the volumetric pump. The pumping portion of the flexible tube fills with liquid when the inlet cracking valve is fully opened and is urged to expand by jaws (236) on pivotally-mounted arms (234). The arms are forced to pivot, as tubing reshaper rollers (160), disposed on the plunger, roll along the inner surface (232) of each arm.

Abstract: A method and apparatus for detecting proximal and distal occlusions of flexible tubing in a positive displacement pump. A volumetric pump (30) includes a motor (146) that rotatably drives a cam assembly (142). The rotating cam assembly actuates a plunger (48), causing it to compress a pumping portion (34b) of a flexible tubing (34), compression of the tubing displaces fluid trapped within the pumping portion, causing it to flow past an outlet cracking valve (52). A proximal pressure sensor (44) and a distal pressure sensor (56) each produce signals indicative of the pressure within the proximal portion and distal portion of the flexible tubing, which are used to determine whether a proximal or distal occlusion of the flexible tubing has occurred. Both pressure sensors comprise strain gauges connected to flexures that apply a spring-biased force against the proximal and distal portions of the flexible tubing.

Abstract: A "cracking valve" for use in a volumetric pump. A volumetric pump (30) includes a plunger (48) for compressing a pumping portion (34b) of a flexible tubing that extends through the pump. An inlet cracking valve (46) and an outlet cracking valve (52) are disposed so that they compress the flexible tubing to control fluid flow therethrough. The inlet cracking valve operates in three modes, including a fully open mode, a closed mode that stops fluid flow through the flexible tubing, and a cracking mode. The outlet cracking valve only operates in the closed mode and the cracking mode. As the plunger compresses the flexible tubing, fluid pressure within the pumping portion of the flexible tubing initially builds until it exceeds a predefined cracking pressure, forcing open the inlet cracking valve, which is in its cracking mode, so that excess fluid is forced back to a container (32).