Medical fluid pumping systems and related devices and methods

The present disclosure relates to medical fluid pumping systems and related devices and methods.

Dialysis is a treatment used to assist patients with inadequate renal function. There are two main dialysis methods, hemodialysis and peritoneal dialysis. During hemodialysis (HD), the patient's blood is passed through the dialyzer of the dialyzer, while the dialysis solution or dialysate is also passed through the dialyzer. The semipermeable membrane in the dialyzer can separate blood from the dialysate in the dialyzer and allow diffusion and osmotic exchange between the dialysate and the bloodstream. As a result of these exchanges across the membrane, waste products containing solutes such as urine and creatinine are removed from the blood. These exchanges also regulate the concentration of other substances in the blood, such as sodium and water, and in this way the dialysis machine acts as an artificial kidney to wash the blood.

During peritoneal dialysis (PD), the patient's peritoneal cavity is regularly infused with dialysis solution or dialysate. The back of the patient's peritoneum acts as a natural semipermeable membrane that allows diffusion and osmotic exchange between the solution and the bloodstream. As a result of these exchanges on the patient's peritoneum, such as continuous exchanges on the dialyzer in HD, waste products containing solutes such as urine and creatinine are removed from the blood, such as sodium and water in the blood. The concentration of other substances is regulated.

Many PD devices are designed to automatically inject and retain dialysate into the patient's peritoneal cavity and drain the dialysate from the patient's peritoneal cavity. Treatment typically lasts several hours, but often begins with an initial drainage procedure that drains the dialysate used or consumed to empty the peritoneal cavity. The procedure then follows a series of filling, retention, and discharge phases that follow. Each phase is called a cycle.

<figref num="1">A perspective view of a peritoneal dialysis (PD) system with a PD circulator positioned on a portable cart.</figref><figref num="2">The perspective view of the PD circulation device and the PD cassette of the PD system of FIG. The door of the PD circulation device is in the open position to show the inner surface of the PD circulation device that interfaces with the PD cassette during use.</figref><figref num="3">Among other things, the opening of the PD circulation device of FIG. 1 shows a piston having a piston head with a spring-loaded latch mechanism that can be used to mechanically connect the piston head to the associated dome-shaped member of the PD cassette. A perspective view of the cassette compartment.</figref><figref num="4">FIG. 2 is a cross-sectional view of the PD circulation device of FIG. 1 illustrating a single spring-loaded latch mechanism for a piston head.</figref><figref num="5">An exploded perspective view of one of the pistons of the PD circulation device of FIG.</figref><figref num="6">Side view of one latch lock on the piston head of the PD circulation device in Figure 1.</figref><figref num="7">Sectional view of the latch lock cut along line 7-7 in Figure 6.</figref><figref num="8">Top view of one sliding latch of the piston head of the PD circulation device in Figure 1.</figref><figref num="9">Sectional view of the sliding latch cut along line 9-9 in Figure 8.</figref><figref num="10">An exploded perspective view of the PD cassette of FIG. 1 with a dome-shaped tightening member that can be mechanically connected to the piston head of the PD circulation device of FIG.</figref><figref num="11">Sectional perspective view of the fully assembled PD cassette of FIG.</figref><figref num="12">FIG. 10 is a perspective view of the fully assembled PD cassette from the flexible membrane and dome-shaped tightening member side of the PD cassette.</figref><figref num="13">A perspective view of the fully assembled PD cassette of FIG. 10 from the rigid base side of the PD cassette.</figref><figref num="14">Partial perspective view of the PD cassette in the cassette compartment of the PD circulation device of the PD system of Figure 1.</figref><figref num="15A">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="15B">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="15C">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="15D">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="15E">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="15F">Sectional diagram of the PD system of FIG. 1 in which PD cassettes are located within the cassette compartment of the PD circulation device in different phases of pumping operation.</figref><figref num="16">The PD of the PD system of Figure 1, exemplifying a horn, or protrusion, extending from the rear surface of the piston head that allows the piston head to be automatically detached from the dome-shaped tightening member of the PD cassette. One cross-sectional view of the piston head of the PD circulation device of the PD system of Figure 1 mechanically connected to one of the dome-shaped tightening members of the cassette.</figref><figref num="17">The dome shape of the PD cassette in the PD system of Figure 1, exemplifying one, or protrusion, extending from the rear surface of the piston head that allows the piston head to be automatically detached from the dome-shaped tightening member of the PD cassette. One cross-sectional view of the piston head of the PD circulation device of the PD system of Figure 1 mechanically connected to one of the tightening members.</figref><figref num="18">Fig. 1 is mechanically connected to one of the dome-shaped tightening members of the PD cassette of the PD system of Fig. 1, which illustrates the process of automatically disconnecting the piston head from the dome-shaped tightening member of the PD cassette. One double cross section of the piston head of the PD circulation device of the PD system.</figref><figref num="19">Fig. 1 is mechanically connected to one of the dome-shaped tightening members of the PD cassette of the PD system of Fig. 1, which illustrates the process of automatically disconnecting the piston head from the dome-shaped tightening member of the PD cassette. One double cross section of the piston head of the PD circulation device of the PD system.</figref><figref num="20">Sectional diagram of another PD circulation device with a transmissable piston head with a peripheral flange that allows the piston head to be mechanically connected to the dome-shaped tightening member of the PD cassette.</figref><figref num="21A">Sectional diagram of the PD cassette in the cassette compartment of the PD circulation device of FIG. 20 in different phases of pumping operation.</figref><figref num="21B">Sectional diagram of the PD cassette in the cassette compartment of the PD circulation device of FIG. 20 in different phases of pumping operation.</figref><figref num="21C">Sectional diagram of the PD cassette in the cassette compartment of the PD circulation device of FIG. 20 in different phases of pumping operation.</figref><figref num="22">A perspective view of a PD cassette with a dome-shaped tightening member having a peg that allows the dome-shaped tightening member to be mechanically connected to a translatable piston head of the PD circulation device.</figref><figref num="23">The internal features of the piston head are shown by broken lines and engage with one peg of the dome-shaped tightening member of the PD cassette in FIG. 22 to mechanically connect the piston head to the dome-shaped tightening member of the PD cassette. Side view of a translationally movable piston head with a recess including a clamp with elastic fingers that can be fitted.</figref><figref num="24">Front view of the piston head in FIG. 23.</figref><figref num="25">The internal features of the piston head are shown by broken lines and engage with one peg of the dome-shaped tightening member of the PD cassette in FIG. 22 to mechanically connect the piston head to the dome-shaped tightening member of the PD cassette. Side view of a translationally movable piston head with a recess including a clamp with elastic fingers of slightly different configurations to fit.</figref><figref num="26">Front view of the piston head in FIG. 25.</figref>

In one aspect of the invention, the medical fluid pumping system comprises a medical fluid pumping device with a piston head that can be displaced linearly and a medical fluid cassette that can be fixed to the medical fluid pumping device. The medical fluid cassette has a base, a flexible membrane attached to the base such that the flexible membrane and the base cooperate to form a fluid pump chamber at least partially, and a tightening attached to the flexible membrane. It is equipped with a member. The tightening member forms a recess configured to receive the piston head of the medical fluid pumping device, and the tightening member is when the piston head is disposed in the recess and linearly separates from the base of the cassette. To increase the volume of the fluid pump chamber by engaging the engaging surface of the piston head with the engaging surface of the tightening member and pulling the tightening member and the flexible film to which the tightening member is attached away from the base. Has an engaging surface that engages with the engaging surface of the piston head when the piston head is disposed in the recess.

In another aspect of the invention, the medical fluid cassette is a base, a flexible membrane attached to the base such that the flexible membrane and the base work together to form a fluid pump chamber at least in part, and possible. It includes a tightening member attached to the flexible membrane. The tightening member forms a recess configured to receive the piston head of the medical fluid pumping device, and when the piston head is disposed within the recess and linearly separates from the base of the cassette, the piston. The head engages the engaging surface of the tightening member, pulling the tightening member and the flexible film to which the tightening member is attached away from the base, and the piston head is placed in the recess to increase the volume of the fluid pump chamber. It has an engaging surface that engages with the piston head when disposed.

In a further aspect of the invention, the medical fluid pumping device comprises a piston head that can be linearly displaced and is configured to be disposed within a recess formed by a tightening member of the medical fluid cassette. In the piston head, when the piston head is disposed in the recess and linearly separates from the base of the cassette, the engaging surface of the piston head engages with the engaging surface of the tightening member, and the tightening member and The piston head is placed in the recess to pull the flexible film to which the tightening member is attached away from the base and increase the volume of the fluid pump chamber formed in the cassette between the flexible film and the base. It has an engaging surface configured to engage the engaging surface of the medical fluid cassette when disposed.

In an additional aspect of the invention, the medical fluid pumping method involves feeding the piston head into a recessed region of the tightening member of the medical fluid cassette and mechanically connecting the piston head to the tightening member, followed by The piston head is reciprocated to alternately move the tightening member backward and forward, thereby alternately drawing the fluid into the fluid pump chamber of the cassette and forcibly expelling the fluid from the fluid pump chamber of the cassette. Including the steps to be performed.

Implementations can include one or more of the following features: In some implementations, the medical fluid cassette can be secured to the medical fluid pumping device by disposing the medical fluid cassette within a cassette compartment formed by the medical fluid pumping device.

In some implementations, a cassette compartment is formed between the door and the cassette interface of the medical fluid pumping device. In some implementations, the tightening member is approximately centered with respect to the fluid pump chamber of the medical fluid cassette.

In some implementations, the tightening member comprises a substantially dome-shaped member. In some implementations, the engaging surface of the tightening member is the surface of a substantially dome-shaped member that extends radially inward.

In some implementations, the protrusions extend continuously around the peripheral region of the nearly dome-shaped member. In some implementations, the tightening member comprises a peg extending from the surface of the dome-shaped member.

In some implementations, the engaging surface of the tightening member is the surface of the enlarged head of the peg. In some implementations, the piston head comprises a body and a contact surface that extends radially beyond the periphery of the body. The contact surface of the piston head is configured to come into contact with the contact surface of the tightening member of the medical fluid cassette when the piston head is inserted into the recess of the tightening member.

In some implementations, the contact surfaces are angled in the range of about 30 degrees to about 60 degrees with respect to the longitudinal axis of the piston head. In some implementations, the contact surface of the piston head is configured to move radially inward when the piston head is inserted into the recess of the tightening member.

In some implementations, the contact surface of the piston head is the surface of the latch that is radially movable with respect to the body of the piston head. In some implementations, the contact surface of the tightening member is configured to deflect radially outward when the piston head is inserted into the recess of the tightening member.

In some implementations, the contact surface of the tightening member is the surface of a radially inwardly extending protrusion of the tightening member. In some implementations, the piston head has a latch that is fixed to the body of the piston head, the engaging surface of the piston head is the surface of the latch, and the latch is that the surface of the latch is the surface of the body. It has an extension position that is positioned radially outward from the periphery.

In some implementations, the latch has a retracted position where the surface of the latch is positioned radially inward from the periphery of the body. In some implementations, the piston head is secured to the body of the piston head and the engagement surface of the second latch is radially outwardly positioned from the periphery of the body to engage the latch. It further comprises a second latch having a retracted position whose surface is positioned radially inward from the periphery of the body.

In some implementations, the body portion comprises a front member and a rear member, and the latch is positioned within the space formed between the front member and the rear member. In some implementations, the piston head is the associated first angled surface of the latch such that the radial inward movement of the latch causes the axial movement of the latch lock in the first axial direction. Further equipped with a latch lock with a first angled surface placed adjacent to Eh.

In some implementations, the first angled surface makes an angle ranging from about 30 degrees to about 60 degrees with respect to the longitudinal axis of the piston head. In some implementations, the first angled surface of the latch and the first angled surface of the latch lock form approximately the same angle with respect to the longitudinal axis of the piston head.

In some implementations, the piston head further comprises a spring disposed between the latch lock and the front member, which resists the axial movement of the latch lock in the first axial direction. To do.

In some implementations, the latch and latch lock move the latch radially inward and the spring stretches when the force applied to the latch to move the latch lock axially is released. The latch lock is configured to move in the second axial direction opposite to the first axial direction, causing a radial outward movement of the latch.

In some implementations, the latch lock is the associated second angled surface of the latch such that the axial movement of the latch lock in the second axial direction causes the radial outward movement of the latch. It has a second angled surface that is placed adjacent to it.

In some implementations, the latch forms a slot in which the legs of the latch lock are located, and the first and second angled surfaces of the latch lock are the legs. The first angled surface and the second angled surface of the latch are the surfaces that form the slots.

In some implementations, the piston head comprises a body and a flange that extends at least partially around the periphery of the body, and the engaging surface of the piston head is at the surface of the piston head flange. is there.

In some implementations, the tightening member has a protrusion that extends at least partially around the periphery of the recess, and the engaging surface of the tightening member is the surface of the protrusion of the tightening member. In some implementations, the tightening member is a nearly dome-shaped member.

In some implementations, the protrusions extend continuously around the periphery of the recess. In some implementations, the outer diameter of the piston head flange is greater than the inner diameter of the tightening member flange, and the piston head and tightening member are the piston head so that the piston head can be disposed in the recess. Is made so that at least one of the flanges is radially deflected with respect to the other of the flanges when the is inserted into the recess of the tightening member.

In some implementations, the piston head is provided with a clamp, the tightening member is provided with a peg configured to be releasably engaged by the clamp, and the engaging surfaces of the piston head and tightening member are respectively. , Clamps and peg surfaces.

In some implementations, the clamp is positioned within the bore formed by the body of the piston head. In some implementations, the clamp comprises a first elastic finger and a second elastic finger that are configured to deflect and separate from each other when the pegs are received within the clamp.

In some implementations, each of the first elastic finger and the second elastic finger has a first protrusion extending radially inward from the base portion of each elastic finger. In some implementations, the anterior surface of each first protrusion of the elastic finger is angled with respect to the longitudinal axis of the piston head, whereby the first elastic finger and the second elastic finger are pegged. Are received in the clamps and deflect away from each other as they slide along the anterior surface of each first protrusion.

In some implementations, the anterior surface of each first protrusion of the elastic finger forms an angle ranging from about 30 degrees to about 60 degrees with respect to the longitudinal axis of the piston head. In some implementations, the posterior surface of each first protrusion of the elastic finger is angled with respect to the longitudinal axis of the piston head, whereby the first elastic finger and the second elastic finger are pegged. Are removed from the clamps and deflect away from each other as they slide along the rear surface of each first protrusion.

In some implementations, the posterior surface of each first protrusion of the elastic finger forms an angle ranging from about 30 degrees to about 60 degrees with respect to the longitudinal axis of the piston head. In some implementations, each of the first and second elastic fingers extends radially inward from the base of each elastic finger and is axially offset from the first protrusion of each finger. It further comprises a second protrusion that allows the peg to rest between the respective first and second protrusions of the elastic finger when the peg is disposed within the clamp.

In some implementations, the piston head further comprises a shaft, the clamp and body are axially movable with respect to the shaft, and the shaft is retracted a certain distance with respect to the shaft. Sometimes the elastic fingers of the clamp are configured to deflect away from each other.

In some implementations, the rear surface of each second protrusion of the elastic finger is positioned to contact the shaft when the body of the piston head and the clamp are retracted by that distance with respect to the shaft. The rear surface of each second protrusion of the elastic finger is angled with respect to the longitudinal axis of the piston head so that the first elastic finger and the second elastic finger are the body of the piston head. And when the clamps are retracted by that distance with respect to the shaft, they deflect away from each other.

In some implementations, the back surface of each second protrusion of the elastic finger forms an angle ranging from about 30 degrees to about 60 degrees with respect to the longitudinal axis of the piston head. In some implementations, the anterior surface of each second protrusion of the elastic finger is approximately perpendicular to the longitudinal axis of the piston head.

In some implementations, the piston head and tightening member are mechanically connected as the piston head is moved towards the base of the cassette and detached as the piston head moves away from the base of the cassette. It will be manufactured.

In some implementations, the piston heads are located within the recesses of the tightening members, and the engaging surfaces come into contact with each other when the piston heads and the tightening members are mechanically connected. In some implementations, the piston head and tightening member is approximately 22.24N (5.0) to dispose the piston head within the recess of the tightening member so that the piston head and tightening member are mechanically connected. Manufactured to require an axial force of approximately 222.4N (50lbf) from lbf).

In some implementations, the piston head and tightening member have at least 22.68 kg (50 lbs) of axial force to remove the piston head from within the tightening member recess so that the piston head and tightening member are separated from each other. Manufactured to require.

In some implementations, the medical fluid pumping device is a dialysis device. In some implementations, the dialysis machine is a peritoneal dialysis machine. In some implementations, the tightening member is mechanically attached to the piston head as the piston head is moved towards the base of the cassette and from the piston head as the piston head moves away from the base of the cassette. Manufactured to be separated.

In some implementations, the medical fluid cassette is a dialysis fluid cassette. In some implementations, the dialysis fluid cassette is a peritoneal dialysis fluid cassette. In some implementations, the piston head is advanced into the recessed area of the tightening member with an axial force of about 22.24N (5lbf) to about 222.4N (50lbf).

In some implementations, the medical fluid pumping method further comprises the step of retracting the piston head by a distance after the reciprocating motion of the piston head to separate the piston head from the tightening member of the medical fluid cassette.

In some implementations, the piston head is retracted from the recessed area of the tightening member with an axial force of at least 22.68 kg (50 lbs). In some implementations, the medical fluid cassette has a base, a flexible membrane attached to the base such that the flexible membrane and the base work together to form a fluid pump chamber at least partially, and a flexible membrane. It includes a tightening member attached to the membrane. The tightening member is such that when the piston head is disposed in the recess and linearly separates from the base of the cassette, the engaging surface of the piston head engages with the engaging surface of the tightening member and the tightening member and tightening. The piston head when the piston head is placed in the recess to pull the flexible film to which the member is attached away from the base, increase the volume of the fluid pump chamber, and draw fluid into the fluid pump chamber. Has an engaging surface that engages with the engaging surface of the.

Implementations can include one or more of the following advantages: In some implementations, relatively simple mechanical connections, such as snap-fitting connections, can be used to connect the piston head of the medical fluid pumping device to the tightening member of the medical fluid cassette. As a result, the system should be easier to use, cheaper, and quieter than some medical fluid pumping systems that utilize a vacuum-based connection between the medical fluid pumping device and the medical fluid cassette. Can be done.

In some implementations, the piston head of the medical fluid pumping device is automatically mechanically coupled to the tightening member of the medical fluid cassette by simply advancing the piston head a certain distance with respect to the cassette for medical fluid pumping. The piston head of the device can be automatically mechanically detached from the tightening member of the medical fluid cassette by simply retracting the piston head a distance with respect to the cassette. As a result of performing the automatic connection and disconnection process, the operator of the device does not have to perform a manual process of connecting and disconnecting the piston head and the tightening member, thus making the system easier to use and treatment. The risk of human error that may adversely affect the system is reduced.

In some implementations, the piston head tightens the mechanical connection and disconnection of the piston head and its associated tightening members on the cassette with the piston head. It is provided with a retractable latch mechanism that allows it to be performed while reducing (eg, minimally) the amount of force that must be applied to the squeeze member. This arrangement configuration can reduce (eg, minimize) deformation of the piston head and tightening members resulting from the connecting and disconnecting steps, thus increasing the pumping accuracy of the system. In particular, reducing the deformation of the piston head and the tightening member makes it easier to ensure a snug fit between the piston head and the tightening member and therefore the piston head during the pumping process. The movement, such as slippage, that occurs between the and the tightening member can be reduced (eg, minimized).

In some implementations, the engagement surface of the latch is angled with respect to the longitudinal axis of the piston (eg, about 60 to about 70 degrees with respect to the longitudinal axis of the piston). This angled arrangement allows the piston head to be mechanically connected to tightening members of slightly different sizes (eg, due to manufacturing process tolerances). In particular, on angled engagement surfaces, the latch can be snugly engaged with tightening members of slightly different sizes by extending radially outwards by slightly different distances.

Other aspects, features, and advantages will become apparent from the description and drawings, as well as the claims. Elastic finger Elastic finger The present disclosure generally relates to medical fluid pumping systems and related devices and methods. In some cases, a medical fluid pumping system (eg, a peritoneal dialysis (PD) system) has a piston with a piston head that can be mechanically connected to a medical fluid cassette (eg, a PD fluid cassette). It is equipped with a medical fluid pumping device (for example, a PD circulation device). Typically, the cassette comprises a flexible membrane and a tightening member attached to the membrane (eg, a dome-shaped tightening member). The membrane and tightening member rest on the recessed area of the rigid body base of the cassette to form a fluid pump chamber, and the piston of the medical fluid pumping device is designed to be mechanically connected to the tightening member of the cassette. To. When the piston of the medical fluid pumping device is mechanically connected to the tightening member of the cassette and the piston reciprocates, the tightening member and membrane are pulled away from the recessed area of the base, and then the tightening member and membrane are recessed in the base. By advancing towards the region, the fluid alternates between being drawn into the fluid pump chamber and being forced out of the fluid pump chamber. As described below, in some cases, the piston is a cassette by simply moving the piston towards the base of the cassette and engaging with a tightening member prior to treatment (eg, PD treatment). It is automatically mechanically connected to the tightening member of the cassette, and after the treatment is completed, the piston is automatically separated from the tightening member of the cassette by simply moving the piston away from the base of the cassette and engaging and disengaging with the tightening member. sell.

With reference to FIG. 1, it can be seen that the PD system 100 includes a PD circulation device (also referred to as a PD device) 102 mounted on the cart 104. Also referring to FIG. 2, the PD circulation device 102 is disposed in a cassette compartment 114 in which the housing 106, the door 108, and the cassette 112 are formed between the cassette interface 110 and the closed door 108. It can be seen that it includes a cassette interface 110 that sometimes contacts the disposable PD cassette 112. The heating device tray 116 is positioned above the housing 106. The heating device tray 116 has a size and shape that accommodates a bag of dialysis solution (eg, a 5 liter bag of dialysis solution). The PD circulator 102 also includes a touch screen 118 and an additional control button 120 that can be operated on the user (eg, patient) side to allow, for example, the setup, start, and / or end of PD treatment.

The dialysis solution bag 122 is suspended from a finger on the side of the cart 104 and is heated. The storage bag 124 is positioned on the heating device tray 116. The dialysis solution bag 122 and the heating device bag 124 are connected to the cassette 112 via the dialysis solution bag line 126 and the heating device bag line 128, respectively. The dialysis solution bag line 126 can be used to pass the dialysis solution from the dialysis solution bag 122 to the cassette 112 during use, and the heating device bag line 128 can be used to pass the cassette 112 and heating device bag during use. The dialysis solution can be moved back and forth between the 124 and the dialysis solution. In addition, the patient line 130 and the drainage line 132 are connected to the cassette 112. The patient line 130 is connected to the patient's abdomen via a catheter and can be used to move the dialysis solution between the cassette 112 and the patient during use. The drainage line 132 is connected to the drainage or drainage receptor and can be used to pass the dialysis solution from the cassette 112 to the drainage or drainage receptor during use.

FIG. 3 shows a more detailed view of the door 108 of the cassette interface 110 and the PD circulation device 102. As shown, the PD circulation device 102 is axially movable within piston access ports 136A, 136B formed within the cassette interface 110, piston shafts 135A, 135B (piston shaft 135A). Is provided with pistons 133A, 133B to which piston heads 134A, 134B are attached). The piston shafts 135A, 135B are connected to a motor that can operate the piston heads 134A, 134B to move axially inward and outward within the piston access ports 136A, 136B. PD when cassette 112 (shown in FIGS. 2 and 10-13) is positioned in cassette compartment 114 of PD circulation device 102 with door 108 closed, as described below. The piston heads 134A, 134B of the circulation device 102 are the pump chambers 138A, 138B of the cassette 112 so that the piston heads 134A, 134B can be mechanically connected to the tightening member of the cassette 112 resting on the pump chambers 138A, 138B. Is aligned with. As a result of this arrangement, the piston heads 134A and 134B move toward the cassette 112 during treatment, reducing the volume of the pump chambers 138A and 138B and forcing the dialysis solution to be expelled from the pump chambers 138A and 138B. However, when the piston heads 134A and 134B are retracted from the cassette 112, the volumes of the pump chambers 138A and 138B increase, and the dialysate solution is drawn into the pump chambers 138A and 138B.

FIG. 4 is a cross-sectional diagram of the PD circulation device 102 illustrating the piston 133A disposed within the piston access port 136A. FIG. 5 is an exploded perspective view of the piston 133A. Since the pistons 133A and 133B are structurally and functionally the same, the piston 133B will not be described in detail separately. As shown in FIGS. 4 and 5, the piston 133A comprises a piston shaft 135A to which the piston head 134A is attached. The piston head 134A comprises a rear member 137A and a front member 139A, between which a latch lock 141A, a latch lock spring 143A, and two sliding latches 145A, 147A are positioned. The rear member 137A and the front member 139A are secured together to hold the latch lock 141A, the latch lock spring 143A, and the two sliding latches 145A, 147A in the accommodation position between them. Typically, the rear member 137A and the front member 139A are fastened together with screws. However, any of a variety of other tightening techniques such as riveting, welding, gluing, etc. can be used in place of or in addition to this.

The piston shaft 135A has a reduced diameter front portion 149A having a size and shape that fits within a bore formed within the stem 151A of the rear member 137A of the piston head 134A. Typically, the piston head 134A has a stem 15 on the inner surface of the front portion 149A and the stem 151A, which have a smaller diameter of the piston shaft 135A. It has threads on the outer and inner surfaces, respectively, so that it is secured to the piston shaft 135A by screwing 1A onto the reduced diameter front portion 149A of the piston shaft 135A. This arrangement allows the piston head 134A to be easily removed from the piston shaft 135A for cleaning, repair, or replacement. Alternatively or additionally, any of a variety of other fixing techniques such as clipping, welding, gluing, etc. can be used to secure the piston head 134A to the piston shaft 135A.

Still referring to FIGS. 4 and 5, the front end region of the latch lock spring 143A enters the recess 153A formed in the front member 139A of the piston head 134A, and the rear end region of the spring 143A , Latch lock 141A can be seen to come into contact with the front facing surface. Latch lock 141A includes legs 155A, 157A that fit into slots 169A, 171A of sliding latches 145A, 147A. Slots 169A and 171A are arranged adjacent to the inner and outer surfaces of the legs 155A and 157A, respectively, and are formed by the inner and outer surfaces of sliding latches 145A and 147A having approximately the same angular direction.

The sliding latches 145A, 147A are slidably positioned within the space 173A, 175A (shown in FIG. 4) formed between the rear member 137A and the front member 139A. Spaces 173A, 175A have a size and shape that allows the sliding latches 145A, 147A to slide radially inward and radially outward. As described in more detail below, when the latch lock 141A moves forward relative to the front member 139A and compresses the spring 143A, the inner surfaces of the legs 155A, 157A of the latch lock 141A slide. It contacts the correspondingly angled adjacent surfaces of the latches 145A, 147A. Due to the angle of these adjacent surfaces, when the latch lock 141A moves forward, the sliding latches 145A, 147A move radially inward. Similarly, when a radial inward force is applied to the sliding latches 145A, 147A, the surfaces of the sliding latches 145A, 147A, which are placed adjacent to the outer surfaces of the legs 155A, 157A of the latch lock 141A, are affected. It contacts the latch lock 141A and applies a radial inward force to the latch lock 141A. Due to the geometric shape of these mating surfaces, when a radial inward force is applied to the outer surfaces of the legs 155A and 157A of the latch lock 141A, the latch lock 141A advances toward the front member 139A. , Compress spring 143A. When the radial inward force applied to the sliding latches 145A and 147A that compress the spring 143 to the latch lock 141A is relaxed, the spring 143A expands and moves the latch lock 141A backward, and the sliding latch. Move 145A and 147A outward in the radial direction.

With reference to FIGS. 5-7, it can be seen that the latch lock 141A includes a U-shaped member 180A forming one 170A, 172A extending rearward. The legs 155A, 157A extend forward from the U-shaped member 180A at an acute angle with respect to the longitudinal axis of the piston 133A when the piston 133A is fully assembled. The feet 182A and 184A are positioned near the front ends of the legs 155A and 157A, respectively. The feet 182A, 184A have a front surface that is approximately perpendicular to the longitudinal axis of piston 133A. The front of the feet 182A, 184A is the surface facing the back of the front member 139A of the piston head 134A when the latch lock 141A has moved completely forward and the spring 143A is fully compressed. Can come in contact. The latch lock 141A extends forward from the central region of the U-shaped member 180A and also has a protrusion 186A (shown in FIG. 7) that extends to the inner surface of the legs 155A, 157A or is integrally formed. Be prepared. The protrusion 186A supports the rear end of the spring 143A.

The dimensions of the piston head 134A and its various components depend on a number of factors, including the type of cassette intended to be used together. Referring to FIG. 6, the latch lock 141A has a total length L.₁It can be seen that this is measured from the frontmost point to the rearmost point along the longitudinal axis of the piston 133A. Length L₁Can range from about 1.27 centimeters (0.5 inches) to about 2.54 centimeters (1.0 inches) (eg, 1.905 centimeters (0.75 inches)). Axial length L of the part of the latch lock 141A extending forward from the front point of the U-shaped member 180A₂Can range from about 0.762 centimeters (0.3 inches) to about 1.016 centimeters (0.4 inches) (eg, 0.89662 centimeters (0.353 inches)). Length L of linear segment of 170A and 172A respectively₃Can range from about 0.635 centimeters (0.25 inches) to about 0.889 centimeters (0.35 inches) (eg, 0.73914 centimeters (0.291 inches)). Height H of legs 155A, 157A measured perpendicular to the longitudinal axis of piston 133A₁Can range from about 1.27 centimeters (0.5 inches) to about 2.54 centimeters (1.0 inches) (eg, 1.905 centimeters (0.75 inches)). Distance D between the bottom of the top 170A and the top of the bottom 172A₁Can range from about 1.27 centimeters (0.5 inches) to about 3.81 centimeters (1.5 inches) (eg, 2.413 centimeters (0.95 inches)). Distance D between the top of the top 170A and the bottom of the bottom 172A₂Can range from about 1.905 centimeters (0.75 inches) to about 3.175 centimeters (1.25 inches) (eg, 2.921 centimeters (1.15 inches)).

Referring to FIG. 7, the angle α measured between the anterior surface of the feet 182A, 184A and the outer and inner surfaces of the legs 157A, respectively.₁And α₂Can be found to be in the range of about 15 to about 75 degrees (eg, the range of about 30 to about 60 degrees, about 45 degrees). The other leg 155A of the latch lock 141A is a mirror image of the leg 157A. As pointed out above, the anterior surfaces of the feet 182A, 184A are approximately perpendicular to the longitudinal axis of piston 133A (ie, the horizontal axis as shown in FIGS. 4 and 7). Therefore, the outer and inner surfaces of the legs 155A and 157A are at angles of about 15 to about 75 (for example, about 30 to about 60, about 45) with respect to the longitudinal axis of the piston 133A. Make up. Distance D from the outer surface of the leg 155A to the outer surface of the leg 157A at the front ends of the legs 155A, 157A₃Can range from about 2.032 centimeters (0.8 inches) to about 2.54 centimeters (1.0 inches) (eg, 2.29616 centimeters (0.904 inches)). The thickness T of the leg 155A, which is almost the same as the thickness of the leg 157A.₁Is typically slightly smaller than the sliding latches 145A, 147A slots 169A, 171A (eg, about 0.0254 centimeters (0.01 inches) to about 0.0508 centimeters (0,02 inches) smaller). Leg 155A thickness T₁Can be, for example, from about 0.1778 centimeters (0.07 inches) to about 0.3556 centimeters (0.14 inches) (eg, 0.28702 centimeters (0.113 inches)).

Then referring to FIGS. 5, 8 and 9, the sliding latch 145A is first used when the piston head 134A is mechanically connected to the dome-shaped member 161A, as described below. It can be seen that it has a retracted surface or a front angled surface 188A that contacts the dome-shaped member 161A. The sliding latch 145A also comprises a lead-out or rear angled surface 190A that contacts the dome-shaped member 161A when the piston head 134A is detached from the dome-shaped member 161A. The outer edge of the rear angled surface 190A and the outer edge of the central portion of the sliding latch 145A extending from the rear angled surface 190A are arched. These outer edges are dome-shaped members 161A It may have a radius of curvature close to the radius of curvature of the inner surface of the. The sliding latch 145A is located adjacent to slot 169A and has a notch sized and shaped to accommodate part of the protrusion 186A extending from latch lock 141A when the piston head 13A is fully assembled. Further equipped with part 192A.

With reference to Figure 8, in some implementations the sliding latch 145A ranges from about 2.286 cm (0.9 inches) to about 2.794 (1.1 inches) (eg 2.4765 cm (0.975 inches) or 2.5019 cm. (0.985 inch)) total length L₃, And / or full width W ranging from about 1.651 centimeters (0.65 inches) to about 1.778 (0.7 inches) (eg 1.7018 centimeters (0.67 inches))₁It can be seen that it has. The slot 169A of the sliding latch 145A is typically slightly larger than the leg 155A of the latch lock 141A, which is located in the slot 169A when the piston head 134A is fully assembled. Slot 169A is, for example, a length L ranging from about 1.778 centimeters (0.7 inches) to about 2.286 centimeters (0.9 inches) (eg 2.032 centimeters (0.8 inches)).₄Can have. As shown in Figure 9, slot 169A ranges from about 0.254 centimeters (0.1 inches) to about 0.381 centimeters (0.15 inches) (for example, 0.3175 centimeters (0.125 inches) or 0.3429 centimeters (0.135)). Inch)) width W₂Can have.

Still referring to Figure 9, the rear angled surface 190A has a width W ranging from about 0.381 centimeters (0.15 inches) to about 0.508 centimeters (0.2 inches) (eg 0.43434 centimeters (0.171 inches)).₃It can be seen that can have. The front angled surface 188A has an angle α ranging from about 15 degrees to about 75 degrees (eg, about 30 degrees to about 60 degrees, 45 degrees) with respect to a plane perpendicular to the longitudinal axis of piston 133A.₃It is arranged by. Thus, the front angled surface 188A forms an angle ranging from about 15 degrees to about 75 degrees (eg, a range from about 30 degrees to about 60 degrees, 45 degrees) with respect to the longitudinal axis of piston 133A. The rear angled surface 190A has an angle α ranging from about 15 degrees to about 45 degrees (eg, 20 degrees, 25 degrees, or 30 degrees) with respect to a plane perpendicular to the longitudinal axis of piston 133A.₄Arranged in. Thus, the rear angled surface 190A makes an angle ranging from about 45 degrees to about 75 degrees (eg, 60 degrees, 65 degrees, or 70 degrees) with respect to the longitudinal axis of piston 133A. The inner and outer surfaces of the sliding latch 145A forming slot 169A are at an angle typically approximately the same as the angle at which the inner and outer surfaces of the legs 155A of the latch lock 141A are located, with respect to the longitudinal axis of the piston 133A. Measured angle α₅, Α₆It is arranged by. Angle α₅, Α₆Can be, for example, an angle in the range of about 15 degrees to about 75 degrees (eg, a range of about 30 degrees to about 60 degrees, 45 degrees).

The latch lock spring 143A typically has a spring constant ranging from about 6.7868 kg / cm (38 lbs / inch) to about 11.9662 kg / cm (67 lbs / inch) and typically A radial inward force of approximately 6.67N (1.5lbf) to approximately 42.26N (9.5lbf) applied to the sliding latches 145A, 147A compresses the spring, causing the sliding latches 145A, 147A to be radially inward. Provides enough resistance to prevent it from moving in the direction.

Piston head 134A and piston shaft 135A can be formed from a variety of different polymers, metals, and / or alloys. The rear member 137A, front member 139A, and latch lock 141A are typically formed from materials that are comparatively rigid, wear resistant, and have a relatively low coefficient of friction. Suitable materials for these components Examples of materials include polyoxymethylene (eg Delrin), aluminum, steel, bronze, brass, and PTFE. However, other metals and plastics with a relatively low coefficient of friction can be used in place of or in addition to this. The sliding latches 145A, 147A are similarly typically formed from materials with comparative stiffness, wear resistance and a relatively low coefficient of friction. In some implementations, the sliding latches 145A, 147A are formed from a polytetrafluoroethylene coated 6061 aluminum alloy. Other examples of materials capable of forming sliding latches 145A, 147A include steel, bronze, brass, POM, and PTFE. However, it will be appreciated that some other materials and plastics can be used in place of or in addition to this.

The various components of the piston head 134A and piston shaft 135A can be formed using any of a variety of different techniques, including machining techniques, molding techniques, and / or casting techniques.

With reference to FIG. 3 again, it can be seen that the PD circulation device 102 also includes a plurality of inflatable members 142 positioned within the inflatable member port 144 in the cassette interface 110. The inflatable member 142 aligns with the pressable dome region 146 of the cassette 112 (shown in FIGS. 10-13) as the cassette 112 is positioned within the cassette compartment 114 of the PD circulation device 102. Although only one of the inflatable members 142 is labeled in FIG. 3, it is understood that the PD circulation device 102 includes an inflatable member associated with each of the pressable dome regions 146 of the cassette 112. Will be done. The inflatable member 142 acts as a valve for directing the dialysate solution through the cassette 112 in a desired manner during use. In particular, the inflatable member 142 expands outward beyond the surface of the cassette interface 110 when inflated, contacts the pressable dome region 146 of the cassette 112, and retracts into the inflatable member port 144 when withered. No contact with 112. By inflating some inflatable member 142 and pressing the associated dome region 146 onto the cassette 112, some fluid channels within the cassette 112 can be blocked. Thus, the PD solution is pumped into the cassette 112 by operating the piston heads 134A, 134B and selectively inflates and shrinks the inflatable member 142 into the desired flow path within the cassette 112. It can be guided along.

Still referring to FIG. 3, it can be seen that the positioning pin 148 extends from the cassette interface 110 of the PD circulation device 102. When the door 108 is in the open position, the cassette 112 is on the cassette interface 110 by positioning the top of the cassette 112 below the positioning pin 148 and pushing the bottom of the cassette 112 towards the cassette interface 110. Can be loaded. The cassette 112 is sized to maintain a fixed position between the positioning pin 148 and the spring-loaded latch 150 extending from the cassette interface 110 so that the door 108 can be closed over the cassette 112. .. The positioning pin 148 helps ensure that the cassette 112 in the cassette compartment 114 is properly aligned during use.

The door 108 of the PD circulation device 102, as shown in FIG. 3, forms cylindrical recesses 152A, 152B that are substantially aligned with the pistons 133A, 133B when the door 108 is in the closed position. When the cassette 112 (shown in FIGS. 10-13) is positioned within the cassette compartment 114, the hollow protrusions 154A, 154B of the cassette 112, whose inner surface partially forms the pump chambers 138A, 138B, , Fits in recesses 152A, 152B. The door 108 further comprises a pad that expands in use to compress the cassette 112 between the door 108 and the cassette interface 110. When the pad expands, the part of the door 108 that forms the recesses 152A, 152B is the cassette 11. Supporting the protrusions 154A, 154B of 2, the plane of the door 108 supports the other area of the cassette 112. The door 108 can oppose the force applied by the inflatable member 142, which allows the inflatable member 142 to actuate the pressable dome region 146 on the cassette 112. The engagement between the door 108 and the hollow protrusions 154A, 154B of the cassette 112 holds the cassette 112 in the desired fixed position within the cassette compartment 114, and the pistons 133A, 133B and the fluid pump chamber 138A of the cassette 112, It can also help to further ensure alignment with the 138B.

10 is an exploded perspective view of the cassette 112, FIG. 11 is a cross-sectional perspective view of the fully assembled cassette 112, and FIGS. 12 and 13 are from the membrane side and from the rigid base side, respectively. It is a perspective view of the assembled cassette 112. With reference to FIGS. 10-12, it can be seen that the cassette 112 includes a flexible film 140 attached to the periphery of a rigid body base 156 that resembles a tray. The rigid dome-shaped tightening members 161A and 161B are positioned within the recessed regions 162A and 162B of the base 156. The dome-shaped members 161A, 161B have a size and shape that accommodate the piston heads 134A, 134B of the PD circulation device 102. In some implementations, the domed members 161A, 161B are about 3.81 It has a diameter measured from the outer edge of flanges 164A, 164B, ranging from centimeters (1.5 inches) to about 6.35 centimeters (2.5 inches) (eg, about 5.08 centimeters (2.0 inches)) and has a recessed area 162A. , 162B occupies an area ranging from about 2/3 to about 3/4 of the area. The annular flanges 164A, 164B of the rigid dome-shaped members 161A, 161B are attached to the inner surface of the membrane 140 surrounding the substantially circular openings 166A, 166B formed in the membrane 140 so as to be liquidtight. Apertures 166A, 166B expose rigid dome-shaped members 161A, 161B so that piston heads 134A, 134B can directly contact and mechanically connect to dome-shaped members 161A, 161B during use. To do.

The annular flanges 164A, 164B of the dome-shaped members 161A, 161B, as shown in FIG. 11, are from the side walls of the annular protrusions 168A, 168B and the dome-shaped members 161A, 161B extending inward in the radial direction. Cyclic protrusions 176A and 176B extending outward in the radial direction are formed. When the piston heads 134A, 134B are mechanically connected to the dome-shaped members 161A, 161B, the radially inward protrusions 168A, 168B are the sliding latches 145A, 147A of the piston heads 134A, 134B. Engage with the rear angled surface to securely secure the dome-shaped members 161A, 161B to the piston heads 134A, 134B. Since the membrane 140 is attached to the dome-shaped members 161A and 161B, it is possible if the dome-shaped members 161A and 161B enter and exit the recessed regions 162A and 162B of the base 156 (for example, by the reciprocating motion of the pistons 133A and 133B). The flexible film 140 also goes in and out of the recessed regions 162A and 162B of the base 156. This movement causes the fluid to form between the recessed regions 162A, 162B of the base 156 and the dome-shaped members 161A, 161B and the portion of the membrane 140 resting on the recessed regions 162A, 162B, a fluid pump. It is forcibly taken out of chambers 138A and 138B and drawn into it.

Referring to FIGS. 10 and 12, the ridge 167 is a flexible membrane from the nearly planar surface of the base 156 when the cassette 112 is compressed between the door 108 and the cassette interface 110 of the PD circulation device 102. Extending and contacting the inner surface of the 140, forming a series of fluid passages 158, and an extended portion of the fluid passage 158 (eg, a nearly circular expanded portion) as shown in FIG. It can be seen that it forms a plurality of pressable dome regions 146 (parts). The fluid passage 158 fluidly connects the fluid pipeline connector 160 of the cassette 112, which acts as an inlet / outlet port of the cassette 112, to the fluid pump chambers 138A and 138B. As pointed out above, the various inflatable valve members 142 of the PD circulation device 102 act on the cassette 112 during use. During use, the dialysis solution is fluid pathway 158 and It flows through the dome area 146 to the pump chambers 138A and 138B and from the pump chambers 138A and 138B. At each pressable dome region 146, the membrane 140 can be deflected so that the ridge 167 contacts the planar surface of the base 156 extending from it. Such contact can substantially impede (eg, impede) the flow of dialysate along the region of pathway 158 associated with its dome region 146. Therefore, the flow of the dialysis solution through the cassette 112 can be controlled by selectively expanding the inflatable member 142 of the PD circulation device 102 by utilizing the selective pressing of the pressable dome region 146.

Still referring to FIGS. 10 and 12, it can be seen that the fluid pipeline connector 160 is located along the bottom edge of the cassette 112. As pointed out above, the fluid path 158 in the cassette 112 leads from the pumping chambers 138A, 138B to the various connectors 160. The connector 160 is asymmetrically located along the width portion of the cassette 112. The asymmetrical position of the connector 160 ensures that the cassette 112 is properly positioned within the cassette compartment 114 with the film 140 of the cassette 112 facing the cassette interface 110. The connector 160 is configured to receive fittings at the ends of the dialysis solution bag line 126, the heating device bag line 128, the patient line 130, and the drainage line 132. One end of the fitting can be inserted and joined into each conduit and the other end can be inserted and joined into the associated connector 160. In use by allowing the dialysis solution bag line 126, the heating device bag line 128, the patient line 130, and the drainage line 132 to be connected to the cassette, as shown in FIGS. 1 and 2. The connector 160 allows the dialysate solution to flow in and out of the cassette 112.

The rigidity of the base 156 holds the cassette 112 in place within the cassette compartment 114 of the PD circulation device 102, and the base 156 is brought to the protrusions 154A, 154B by the dome-shaped members 161A, 161B. It helps prevent bending and deformation in response to the applied force and in response to the force applied by the inflatable member 142 to the planar surface of the base 156.

The dome-shaped members 161A, 161B of the base 156 and the cassette 112 can be formed from a variety of relatively rigid materials. In some implementations, the components of the cassette 112 are made from one or more polymers such as polypropylene, polyvinyl chloride, polycarbonate, polysulfone, and other medical grade plastic materials. In some implementations, these components may be formed from one or more metals or alloys, such as stainless steel. These components may instead be formed from a variety of different combinations of materials of the polymers and metals described above. These components of the cassette 112 can be formed using a variety of different techniques, including machining, forming, and casting techniques.

As pointed out above, the membrane 140 is attached to the periphery of the base 156 and to the annular flanges 164A, 164B of the dome-shaped members 161A, 161B. The portion of the membrane 140 that rests on the rest of the base 156 is typically not attached to the base 156. Rather, these portions of the membrane 140 are loosely placed on the ridges 165A, 165B, 167 extending from the planar surface of the base 156. Various attachment techniques, such as adhesive adhesion and thermal adhesion, can be used to attach the membrane 140 to the periphery of the base 156 and to a dome-shaped member. The thickness and material (s) of the membrane 140 are selected so that the membrane 140 is flexible enough to bend to the base 156 in response to the force applied to the membrane 140 by the inflatable member 142. In some implementations, the film 140 has a thickness from about 0.100 microns to 0.150 microns. However, various other thicknesses may be sufficient, depending on the type of material used to form the film 140.

The membrane 140 can be formed using a variety of different materials that can deflect the membrane 140 in response to the movement of the inflatable member 142 without breaking. In some implementations, Membrane 140 comprises a three-layer laminate. In some implementations, for example, the inner and outer layers of the laminate consist of a compound composed of 60% Septon® 8004 thermoplastic rubber (ie, styrene block copolymer hydride), and 40% ethylene. The intermediate layers formed are 25% Tuftec® H1062 (SEBS: Styrene Hydroplastic Elastomer), 40% Engage® 8003 Polyethylene Elastomer (Ethylene Octene Copolymer), and 35% Septon. (Registered Trademark) 8004 Formed from a compound composed of thermoplastic rubber (ie, styrene hydride block copolymer). Membranes can instead include more or less layers and / or can be formed from different materials.

As shown in FIG. 14, prior to treatment, the door 108 of the PD circulator 102 was opened to expose the cassette interface 110, where the cassette 112 had dome-shaped members 161A, 161B pistons of the PD circulator 102. The film 140 is positioned so as to be aligned with 133A and 133B and adjacent to the cassette interface 110. To ensure alignment of the domed members 161A, 161B with the pistons 133A, 133B, the cassette 112 is located between the positioning pin 148 and the spring-loaded latch 150 extending from the cassette interface 110. Positioned to. The asymmetrically positioned connector 160 of the cassette has the probability that the cassette 112 will be mounted with the membrane 140 and the dome-shaped members 161A, 161B facing in the wrong direction (eg, facing outward towards the door 108). Works as a key function to reduce. Alternatively or additionally, the positioning pin 148 is the maximum of protrusions 154A, 154B to prevent the cassette 112 from contacting the positioning pin 148 when the membrane 140 faces outward toward the door 108. It can have dimensions smaller than the protrusion. The pistons 133A, 133B are typically retracted into the piston access ports 136A, 136B when mounting the cassette 112 so that there is no interference between the pistons 133A, 133B and the dome-shaped members 161A, 161B. This simplifies the task of positioning the cassette 112 within the cassette compartment 114.

In FIGS. 15A-15F, the PD cassette 112 is the cassette of the PD circulation device 102 in different phases of pumping operation used to draw the dialysis solution into the pump chamber 138A and forcibly expel the dialysis solution from the pump chamber 138A. -It is a cross-sectional view of the PD system 100 arranged in the compartment 114. The techniques for pumping a solution to and out of another pump chamber 138B are the same and therefore will not be described in detail separately.

FIG. 15A shows a cassette 112 positioned within the cassette compartment 114 immediately after installation. As shown, the cassette 112 is positioned adjacent to the cassette interface 110, and the door 108 is such that the cassette 112 is housed in the cassette compartment 114 between the door 108 and the cassette interface 110. Closed on cassette 112. The piston head 134A is retracted into the piston access port 136A so that the piston head 134A does not interfere with the cassette 112 during installation. With the cassette 112 positioned in the cassette compartment 114, the inflatable pad in the door 108 expands to compress the cassette 112 between the door 108 and the cassette interface 110. This compression of the cassette 112 held the protrusion 154A of the cassette 112 within the recess 152A of the door 108 and pressed the membrane 140 against the ridge 167 extending from the planar surface of the rigid base 156 to be contained. Form fluid path 158 and dome region 146 (shown in Figure 12) To do.

After the cassette 112 is mounted in the cassette compartment 114 of the PD circulation device 102, as shown in FIG. 15B, the piston 133A advances to bring the piston head 134A of the PD circulation device 102 into the dome of the cassette 112. The process of mechanically connecting to the shaped member 161A is started. Piston 133A has velocities ranging from about 2.032 centimeters (0.8 inches) / minute to about 27.94 centimeters (11 inches) / minute, and axes ranging from about 22.24N (5.0lbf) to about 222.4N (50lbf). You can move forward with force. As the piston 133A advances, the front angled surface 188A of the sliding latch 145A and the front angled surface 191A of the sliding latch 147A extend radially inward from the domed member 161A, the annular protrusion 168A. Contact the rear surface. The rear surface of the annular protrusion 168A is approximately perpendicular to the longitudinal axis of piston 133A.

As the piston 133A continues to move forward, the dome-shaped member 161A contacts the inner surface of the portion of the rigid body base 156 that forms the recessed region 162A, as shown in FIG. 15B. The rigid base 156 prevents the dome-shaped member 161A from moving further forward. The film 140 attached to the peripheral flange 164A of the dome-shaped member 161A is also stretched and moved into the recessed region 162A as the piston 133A advances. Due to the angled geometry of the front angled surfaces 188A, 191A of the sliding latches 145A, 147A and the resistance that the rigid base 156 exerts on the forward movement of the dome-shaped member 161A, the sliding latches 145A, 147A Is moved radially inward (ie, towards the longitudinal axis of piston 133A) as the piston head 134A continues to move relative to the dome-shaped member 161A. More specifically, the forward movement of the sliding latches 145A, 147A is advanced by sliding the front angled surfaces 188A, 191A of the sliding latches 145A, 147A, which hit the rear surface of the annular protrusion 168A of the dome-shaped member 161A. It is converted into a combination of motion and radial inward motion. The sliding inward movements of the sliding latches 145A and 147A are then positioned adjacent to the outer surfaces of the legs 155A and 157A of the latch lock 141A and the outer surfaces of the legs 155A and 157A. The mating geometry of the surfaces of the sliding latches 145A and 147A in contact causes forward movement of the latch lock 141A. The forward movement of the latch lock 141A is subject to the resistance of the spring 143A.

FIG. 15C shows the sliding latches 145A, 147A within the radial direction by a sufficient distance to allow the sliding latches 145A, 147A to cross the annular protrusion 168A extending radially inward from the dome-shaped member 161A. It shows the piston head 134A at a certain point during the connecting process that is deflected in the direction. At this position, the outer peripheral surfaces of the sliding latches 145A, 147A, which are approximately parallel to the longitudinal axis of piston 133A, are also approximately parallel to the longitudinal axis of piston 133A, the protrusion 168A of the dome-shaped member 161A. It comes into contact with the inner surface of the piston and slides along the inner surface. The spring 143A is further compressed due to the radially inwardly deflected positions of the sliding latches 145A, 147A.

With reference to FIG. 15D, it can be seen that when the sliding latches 145A, 147A exceed the protrusion 168A, the spring 143A is allowed to extend. Extension of spring 143A causes backward movement of latch lock 141A. As a result, the outer surfaces of the legs 155A, 157A of the latch lock 141A come into contact with the corresponding angled adjacent surfaces of the sliding latches 145A, 147A, whereby the sliding latches 145A, 147A are radially outward. And go under the protrusion 168A of the dome-shaped member 161A. Sliding latches 145A, 147A rear angled surfaces 190A, 193A When the idling latches 145A, 147A move radially outward, they are slightly angled towards the rear of the dome-shaped member 161A (eg, about 88 degrees with respect to the longitudinal axis of the piston head 133A. (At an angle), rest along the front of the protrusion 168A of the dome-shaped member 161A. The sliding latches 145A, 147A wedge under the protrusion 168A as the sliding latches 145A, 147A move radially outward.

The rear angled surfaces 190A, 193A of the sliding latches 145A, 147A allow the piston head 134A to be securely locked within a slightly different sized dome-shaped member. For example, due to imperfections in manufacturing technology, the thickness of the annular protrusion 168A along the longitudinal axis of the piston 133A may be slightly (eg, from about 0.076 mm (0.003 inch)) among the different molded dome-shaped members. It may differ by about 0.127 mm (only 0.005 inch). The rear angled surfaces of the sliding latches 145A, 147A can help ensure that they fit snugly against these domed members.

FIG. 15E illustrates a complete mechanical connection between the piston head 134A and the dome-shaped member 161A in which the sliding latch 145A has moved to the maximum outward displacement position within the dome-shaped member 161A. There is. In this configuration, the overhang 168A of the dome-shaped member 161A is effectively pinched between the rear member 137A of the piston head 134A and the sliding latches 145A, 147A, resulting in the piston head 134A and the dome shape. A secure engagement is made with the member 161A of. As a result of the piston head 134A being securely engaged with the dome-shaped member 161A, the amount of slip of the piston head 134A with respect to the dome-shaped member 161A is reduced (eg, minimized) and therefore accurate pumping is achieved. Can be executed.

As described above, when the piston 133A is mechanically connected to the dome-shaped member 161A, the dome-shaped member 161A has the dome-shaped member 161A in the recessed region 162A of the base 156 of the cassette 112. Advance into the recessed region 162A of the rigid base 156 until it comes into contact with the inner surface. This movement reduces the volume of the pump chamber 138A formed between the dome-shaped member 161A, the membrane 140, and the recessed region of the base 156, thus reducing the fluid in the pump chamber 138A (eg, nominal). The fluid) is forced out of the pump chamber 138A from the fluid path 158 of the cassette through the inlet port 185A (shown in FIG. 10).

Referring to FIG. 15F, it can be seen that after the piston 133A is mechanically connected to the dome-shaped member 161A, the piston 133A is retracted to draw the dialysate solution into the pump chamber 138A. The piston head 134A is mechanically connected to the dome-shaped member 161A, and the dome-shaped member 161A is attached to the membrane 140 of the cassette 112, so that when the piston 133A is retracted, the dome-shaped member 161A and the dome. The portion of the membrane 140 attached to the shaped member 161A moves rearward. As a result, the volume of the pump chamber 138A is increased and the fluid is drawn into the pump chamber 138A.

Since the volumes of the fluid pump chamber 138A and the piston head 134A are known, the linear distance traveled by the piston 133A can be used to determine the volume of dialysis solution drawn into the fluid pump chamber 138A. The linear distance traveled by the piston 133A can be determined based on the number of rotations or steps of the motor used to drive the piston 133A (eg, a stepper motor). Therefore, the volume of solution drawn into the fluid pump chamber 138A can be determined based on the rotation of the motor or the number of steps. This is because the piston head 134A and the dome-shaped member 161A fit together exactly. The accuracy of the volume of the solution as determined by the method is guaranteed.

After drawing the dialysis solution into the pump chamber 138A, the dialysis solution is forcibly expelled from the pump chamber 138A by advancing the piston 133A again and reducing the volume of the pump chamber 138A. Piston 133A typically has a dome-shaped member 161A in contact with or nearly in contact with the inner surface of the recessed region of base 156, with nearly all of the dialysate being exposed to outlet port 187A (shown in FIG. 10). ) To be forcibly expelled from the fluid pump chamber 138A.

This step of drawing the dialysis solution into the fluid pump chamber 138A and then forcibly expelling the dialysis solution from the fluid pump chamber 138A involves the desired amount of dialysis solution to or from a location (eg, to the patient). Repeated until pumped (or from the patient).

As pointed out above, while forcibly pumping the dialysis volume into the pump chambers 138A, 138B and expelling it from the pump chambers 138A, 138B, it selectively inflates some inflatable members 142 of the PD circulation device 102. The pumped dialysis solution can be routed along the desired pathway within the cassette 112.

Referring again to FIGS. 1 and 2, during PD treatment, the patient line 130 may be connected to the patient's abdomen via a catheter and the drainage line 132 to the drainage or drainage receptor. Understand. PD treatment typically begins with draining the patient from the used dialysis solution that remains in the patient's abdomen from the previous treatment. To this end, the pump of the PD circulation device 102 is operated to reciprocate the pistons 133A and 133B to inflate the selected inflatable member 142 and the used dialysis solution from the patient in the fluid pump chamber 138A of the cassette 112. , Pull into 138B. Next, the used dialysis solution is pumped from the fluid pump chambers 138A and 138B to the discharge section via the drainage pipe line 132.

After draining the used dialysis solution from the patient, the heated dialysis solution is transferred from the heating device bag 124 to the patient. To do so, one or more motors of the PD circulation device 102 are operated to reciprocate the pistons 133A, 133B, inflating some inflatable members 142 of the PD circulation device 102, and heating device bag. The warmed dialysis solution is drawn from the heating device bag 124 into the fluid pump chambers 138A and 138B of the cassette 112 through the pipe line 128. The warm dialysis solution is then pumped from the fluid pump chambers 138A, 138B through the patient line 130 to the patient.

After the dialysis solution is pumped from the heating device bag 124 to the patient, the dialysis solution remains in the patient for a period of time. During this residence period, toxins that cross the patient's peritoneum enter the dialysis solution from the patient's blood. As the dialysate stays in the patient, the PD circulator 102 prepares a new dialysate to administer to the patient in subsequent cycles. In particular, the PD device 102 pumps a new dialysis solution from the four full dialysis solution bags 122 into the heating device bag 124 for heating. To this end, the pump of the PD circulation device 102 is actuated to reciprocate the pistons 133A, 133B, inflating some inflatable members 142 of the PD circulation device 102, and through the associated conduit 126. The dialysis solution is drawn from the selected dialysis solution bag 122 into the fluid pump chambers 138A and 138B of the cassette 112. Next, the dialysis solution is pumped from the fluid pump chambers 138A and 138B to the heating device bag 124 via the heating device bag conduit 128.

After the dialysis solution stays in the patient for a desired period of time, the used dialysis solution is pumped from the patient to the drain. The heated dialysis solution is then pumped from the heating device bag 124 to the patient, where the dialysis solution stays for a desired period of time. These steps are the three remaining dialysis Repeat with dialysis solution from two of the solution bags 122. The dialysis solution from the last dialysis solution bag 122 is typically delivered to the patient and left in the patient until subsequent PD treatment.

The dialysis solution is described as being pumped from a single dialysis solution bag 122 into the heating device bag 124, whereas the dialysis solution is replaced by a plurality of dialysis solution bags 122 to the heating device bag 124. Can be pumped inside. Such techniques include, for example, the concentration of dialysis solution in which the dialysis solution in bag 122 has different concentrations (eg, different glucose concentrations) and the concentration desired for treatment is in two or more of bags 122. It is considered to be advantageous when it is in the middle of.

After the PD treatment is complete, the pistons 133A, 133B are retracted by separating the piston heads 134A, 134B from the dome-shaped members 161A, 161B of the cassette. This method will be described with reference to FIGS. 16-19. Since the piston heads 134A and 134B are almost the same, the disconnection step will be described in detail only for the piston head 134A. As shown in FIGS. 16 and 17, which are different cross-sectional views of the piston head 134A connected to the dome-shaped member 161A, one (horn) or protrusion 170A, 172A of the latch lock 141A is a piston. It extends posteriorly through an opening formed within the rear member 137A of the head 134A. One 170A, 172A, one 170A, 172A extends slightly from the rear surface of the rear member 137A, or the rear surface of the rear member 137A, when the latch lock 141A advances to the full front position and the spring 143A is compressed. It has a length that is coplanar with.

Two 170A, 172A can be used to pull the sliding latches 145A, 147A radially inward to separate the piston head 134A from the dome-shaped member 161A of the cassette 112. FIG. 18 is a double cross-sectional view of the piston head 134A mechanically connected to the dome-shaped member 161A. As shown in FIG. 18, when the piston head 134A and the dome-shaped member 161A are mechanically connected, one 170A, 172A penetrates the opening of the rear member 137A and passes through the rear surface of that member. It extends beyond and backwards. At this position, the spring 143A of the piston head 134A extends to hold the latch lock 141 in the rearmost position, whereby the two 170A, 172A protrude through the opening of the rear member 137A.

FIG. 19 is a double cross-sectional view of the piston head 134A configured to be mechanically separated from the dome-shaped member 161A. In this configuration, one 170A, 172A is pushed into the opening of the rear member 137A. As a result, the latch lock 141A is moved to the foremost position and the spring 143A is compressed.

As the piston 133A reciprocates during treatment, the two 170A, 172A line up anteriorly apart from the vertical stopper or surface 174 (shown in FIGS. 15A-15F) of the PD circulation device 102. As a result, one 170A, 172A remains in a fully rearwardly extended position throughout the pumping process. However, after the treatment is complete, the piston 133A is retracted enough distance so that one 170A, 172A backs into the stopper or surface 174 of the PD circulation device 102. As shown in FIG. 19, the operation of retracting the piston 133A is continued, pushing the 170A and 172A into the opening of the rear member 137A and moving the latch lock 141A forward relative to the front member 139A. And thereby compresses the spring 143A. As a result, the angled inner surfaces of the legs 155A, 157A of the latch lock 141A are pressed against the adjacent, similar angled surfaces of the sliding latches 145A, 147A, thereby causing the sliding latches 145A, 147A to The protrusion 168A of the dome-shaped member 161A, which is pulled inward in the radial direction (Fig. 15A). The sliding latches 145A and 147A are disengaged from (shown on ~ 15F). When the piston 133A is further retracted, the piston head 134A backs out of the dome-shaped member 161A of the cassette 112. Alternatively or additionally, due to the elasticity of the stretched membrane 140, the membrane 140 and the dome-shaped member 161A engage the sliding latches 145A, 147A from the protrusion 168A of the dome-shaped member 161A. It can be snapped forward to prevent contact with the piston head 134A.

After the pistons 133A, 133B are separated from the dome-shaped members 161A, 161B of the cassette 112 and backed up in the manner described above, the door 108 of the PD circulation device is opened and the cassette 112 is placed in the cassette compartment 114. Removed from and destroyed.

Since the PD system 100 does not require a vacuum system to draw the liquid into the fluid pump chambers 138A, 138B, a nearly airtight seal between the door 108 and the cassette interface 110 is typically not needed. .. Therefore, the door sealing mechanism of the PD circulation device 102 is simpler and more cost effective than a system with a vacuum system adapted to retract a portion of the cassette membrane that rests on the pump chamber. In addition, less decompression is used compared to some conventional circulation devices, which can result in quieter operation.

We have described some implementations, but other implementations are possible. The piston heads 134A, 134B can be moved radially inward and outward to allow the piston heads 134A, 134B to be mechanically connected to the domed members 161A, 161B of the cassette 112. Although described as having a spring-loaded latch mechanism with sliding latches 145A, 145B, simpler piston heads without such sliding latches may be used instead. it can. FIG. 20 illustrates a PD circulation device 202 comprising a piston 233A in which one such type of piston head 234A is connected to a piston shaft 135A. The PD circulation device 202 is essentially the same as the PD circulation device 102 described above, except that the piston comprises a different type of piston head than the piston in the PD circulation device 102 described above. .. Like the PD circulation device 102, the PD circulation device 202 also comprises a second piston having substantially the same structure and function as the piston 233A illustrated in FIG. 20, and is therefore not described in detail separately.

Still referring to FIG. 20, the piston head 234A is a cassette dome shape that mechanically connects the piston head 234A to a cassette to allow the type of fluid pumping process described above to be performed. It can be seen that it is an integral structure including a peripheral flange 245A that can be engaged with the annular protrusion of the member. The rear surface of the flange 245A may be arranged at an angle ranging from about 45 degrees to about 75 degrees (eg, about 60 degrees) with respect to the longitudinal axis of the piston. Piston head 234A can be formed using any of the materials and techniques described above for piston head 134A. Similarly, the piston head 234A can be secured to the piston shaft 135A using any of the mounting techniques described above for mounting the piston head 134A to the piston shaft 135A.

21A-21C show the PD circulation device 202 in different phases of pumping operation used to draw the dialysis solution into the pump chamber 238A of the cassette 212 and forcibly expel the dialysis solution from the pump chamber 238A of the cassette 212. FIG. 5 is a cross-sectional view of a PD system 200 comprising a PD cassette 212 disposed within a cassette compartment 114 of the. The cassette 212 is very similar to the cassette 112 described above. To. However, the cassette 212 includes a rigid dome-shaped member 261A having a slightly different shape from the dome-shaped member 161A described above. The techniques for pumping the solution to and out of the other pump chambers of the cassette 212 are the same and therefore will not be described in detail separately.

After the cassette 212 is mounted in the cassette compartment 114 of the PD circulation device 202, as shown in FIG. 21A, the piston 233A advances and the piston head 234A of the PD circulation device 202 is dome of the cassette 212. The process of connecting to the shaped member 261A is started. As the piston 233A advances, the flange 245A of the piston head 234A contacts the retractable chamfer or rear surface of the annular protrusion 268A that extends radially inward from the dome-shaped member 261A and pushes the dome-shaped member 261A. Contact the rigid base 156 of the cassette 212. The front surface of the flange 245A of the piston head 234A and the rear surface of the annular protrusion 268A of the dome-shaped member 261A are generally configured to substantially fit together. The preceding anterior surface of the flange 245A of the piston head 234A is typically angled rearward in the range of about 45 degrees to about 75 degrees (eg, about 60 degrees) with respect to the longitudinal axis of the piston 233A. The posterior surface of the annular protrusion is typically angled forward in the range of about 45 to about 75 degrees (eg, about 60 degrees) with respect to the longitudinal axis of piston 233A. Due to the geometry and rigidity of the flange 245A of the piston head 234A, when the piston head 234A is fed into the dome-shaped member 261A of the cassette 212, the protrusion 268A diameters the peripheral side wall of the cassette 212 extending from it. It can be deflected outward so that the flange 245A slides over the protrusion 268A. The dome-shaped member 261A of the cassette 212 is elastic so that the protrusion 268A slides over the protrusion 268A and then the protrusion 268A returns to fit behind the flange 245. The engagement between the flange 245A and the protrusion 268A secures and holds the piston head 234A to the dome-shaped member 261A of the cassette 212, which allows pumping action to be applied to the cassette 212 by the piston 233A. ..

When the piston head 234A is mechanically connected to the dome-shaped member 261A in the manner described above, the dome-shaped member 261A advances into the recessed region 162A of the base 156 and thus is dome-shaped. The volume of the pump chamber 238A formed between the member 261A and the membrane 140 is reduced, which forces the fluid (eg, nominal fluid) in the pump chamber 238A to be expelled from the pump chamber 238A.

With reference to FIG. 21C, it can be seen that the piston 233A is retracted to draw the dialysate solution into the pump chamber 238A. The piston head 234A is mechanically connected to the dome-shaped member 261A, and the dome-shaped member 261A is attached to the membrane 140 of the cassette 212 so that when the piston 233A is retracted, the dome-shaped member 261A and the dome. The portion of the membrane 140 attached to the shaped member 261A moves rearward. As a result, the volume of the pump chamber 238A is increased and the fluid is drawn into the pump chamber 238A.

After drawing the dialysis solution into the pump chamber 238A, the dialysis solution is forcibly expelled from the pump chamber 238A by advancing the piston 233A again and reducing the volume of the pump chamber 238A. As explained above, this step of drawing the dialysis solution into the fluid pump chamber 238A and then forcibly expelling the dialysis solution from the fluid pump chamber 238A is where the desired amount of dialysis solution is present during PD treatment. Repeated until pumped to or from a location (eg, to or from a patient).

After treatment, the piston 233A is retracted more than it is retracted during treatment in order to mechanically disconnect the piston head 234A from the dome-shaped member 261A. This pull Due to the inclusion, the rear surface of the peripheral flange of the dome-shaped member 261A contacts the surface 174 of the PD circulation device 202, thereby preventing the dome-shaped member 261A from further moving backwards. Piston 233A continues to retract such that piston head 234A slides rearward with respect to dome-shaped member 261A. The rear surface of the flange 245A of the piston head 234A is typically angled forward in the range of about 60 to about 80 degrees (eg, about 70 degrees) with respect to the longitudinal axis of the piston 233A. The anterior surface of the annular protrusion 268A is typically angled rearward in the range of about 60 to about 80 degrees (eg, about 70 degrees) with respect to the longitudinal axis of piston 233A. Due to the orientation of these surfaces and the inability of the dome-shaped member 261A to move further rearward, the backward movement of the piston head 234A causes the annular protrusion 268A to extend from it the dome-shaped member 261A. The part of is deflected outward in the radial direction. This allows the flange 245A of the piston head 234A to slide over the annular protrusion 268A, so that the piston head 234A is mechanically separated from the dome-shaped member 261A.

The piston head 234A and the cassette 212 are arranged so that the peripheral side wall of the cassette 212 is deflected outward as the piston head 234A advances into the dome-shaped member 261A and retracts from the dome-shaped member 261A. These are described as being configured in, but in place of or in addition to this, the wall of the piston head 234A extending from the flange 245A is deflected radially inward to the piston. The flange 245A of the head 234A can be designed to slide over the protrusion 268A of the cassette 212.

The cassette 212 and PD circulation device 202 described above are designed so that the rear surface of the peripheral flange of the dome-shaped member 261 contacts the surface 174 of the PD circulation device 202 during the disconnection process. In mounting, the membrane 140 itself may provide sufficient resistance to the rearward movement of the dome-shaped member 261A so that the piston head 234A can be separated from the dome-shaped member 261A.

Other structures can also be used to allow mechanical connection between the piston head and the cassette. As shown in FIG. 22, for example, a cassette 312 that is structurally very similar to the cassette 112 described above is disposed within recessed regions 162A, 162B of the base 156 of the cassette 112. Includes pegs 368A, 368B extending from rigid dome-shaped members 361A, 361B, attached to membrane 140 of cassette 312 in the same manner as the dome-shaped members 161A, 161B of cassette 112 described above. .. Are the pegs 368A and 368B attached to the ends of the stems 370A and 370B attached to the associated dome-shaped members 361A and 361B of the cassette 312 and the stems 370A and 370B opposite the dome-shaped members 361A and 361B, respectively? , Or an enlarged head 372A, 372B integrally formed with its end. As described below, the pegs 368A, 368B may engage the piston head of the PD circulation device in a manner that mechanically connects the dome-shaped members 361A, 361B to the piston head.

23 and 24 are fixed to the piston shaft 135A of one of the PD circulation devices described above, with the recessed region of the base 156 of the cassette 312 and the dome-shaped member 361A and as the piston reciprocates. Illustrates a piston head 334A that can engage the peg 345A of a cassette 312 that can generate a pumping action in the pump chamber formed between the membrane 140. The same piston head can be fixed to another piston shaft 135B of the PD circulation device to generate a similar pumping action in the pump chamber adjacent to the other dome-shaped member 361B. Will be understood. As shown in FIGS. 23 and 24, the piston head 334A has a clamp mechanism 338A with two elastic spring fingers 345A, 347A. Equipped with a bore 336A to accommodate. The central portion of the spring fingers 345A, 347A can be attached, for example, to the annular protrusion 390A extending radially inward of the piston head 334A. The spring fingers 345A, 347A can be attached to the annular protrusion 390A using any of a variety of other attachment techniques such as adhesive bonding, thermal welding, and / or mechanical tightening techniques.

Still referring to FIGS. 23 and 24, the spring finger 345A comprises a front protrusion 349A and a rear protrusion 351A extending radially inward from the base portion of the finger 345A, respectively. , It can be seen that the front protrusion 353A and the rear protrusion 355A, which extend radially inward from the base portion of the finger 347A, are provided, respectively. The front protrusions 349A and 353A are angled with respect to the longitudinal axis of the piston in the range of about 15 to about 75 degrees (eg, in the range of about 30 to about 60 degrees, about 45 degrees). It has a chamfered surface at the front end. In order to mechanically connect the piston head 334A to the peg 368A, the piston head 334A is advanced and placed in the dome-shaped member 361A, and the front surfaces of the protrusions 349A and 353A of the spring fingers 345A and 347A are the peg 368A. Make contact with the enlarged head 372A. Continuing to advance the piston head 334A by the angled orientation of the front surface of the protrusions 349A, 353A causes the spring fingers 345A, 347A to deflect radially outward, thereby causing the protrusions 349A, 353A to bend outward. Sliding along the enlarged head 372A of the peg 368A spreads and separates. The spring fingers 345A and 347A allow the enlarged head 372A of the peg 368A to slide forward beyond the protrusions 349A and 353A, and the expanded head 372A with the front protrusions of the spring fingers 345A and 347A. Spread and separate by a sufficient distance that can be fixed in the space formed between it and the rear protrusion. The anterior surfaces of the rear protrusions 351A and 355A are approximately perpendicular to the longitudinal axis of the piston, which allows the enlarged head 372A of the peg 368A to have the front and rear protrusions of the spring fingers 345A and 347A. Even if the piston head 334A advances further when it is arranged in the space between the spring fingers 345A and 347A, the spring fingers 345A and 347A expand. Never leave. With the piston head 334A and peg 368A magnified in this way, the reciprocation of the piston head 334A moves the perimeter of the dome-shaped member 361A and the membrane 140, thus the fluid is described above. In the same way as above, it is pumped into the pump chamber of cassette 312 and expelled from the pump chamber of cassette 312.

Similar to the front surface of the front protrusions 349A, 353A of the spring fingers 345A, 347A, the rear surface of the rear protrusions 351A, 355A ranges from about 15 degrees to about 75 degrees (eg, about 30 degrees to about 60 degrees). It can be angled in the range up to, about 45 degrees). The internal shaft 357A is located in the axial bore formed within the piston head 334A positioned behind the bore 336A in which the clamp mechanism 338A is housed. The internal shaft 357A is fixed to the housing of the PD circulation device so that the piston head 334A moves relative to the shaft 357A as the piston head 334A reciprocates. In order to disconnect the piston head 334A from the peg 368A after treatment, the piston head 334A is placed in the PD circulation device long enough for the shaft 357A to contact the rear surfaces of the spring fingers 345A, 347A with the posterior protrusions 351A, 355A. Withdrawn. When this contact occurs, the spring fingers 345A, 347A spread apart due to the angled rear surface orientation of the rear protrusions 351A, 355A. When the piston head 334A is further retracted, the front protrusions 349A and 353A return beyond the peg 368A.

Figures 25 and 26 are anchored to the piston shaft 135A of one of the PD circulation devices described above and have a recess in the base 156 of the cassette 312 as the piston reciprocates. Illustrates a slightly different piston head 434A that can engage the peg 345A of the cassette 312 that can generate a pumping action in the pump chamber formed between the region and the dome-shaped member 361A and the membrane 140. ing. As shown in FIGS. 25 and 26, the piston head 434A comprises a bore 436A that houses a clamp mechanism 438A with two elastic spring fingers 445A, 447A. The central portion of the spring fingers 445A, 447A is attached to the annular protrusion 490 extending radially inward of the piston head 434A. The spring fingers 445A, 447A can be attached to the annular protrusion 490A using any of a variety of other attachment techniques such as adhesive bonding, thermal welding, and / or mechanical tightening techniques.

Still referring to FIGS. 25 and 26, it can be seen that the spring fingers 445A, 447A include protrusions 449A, 453A extending radially inward from the base portion of the fingers 445A, 447A. The protrusions 449A, 453A are angled in opposite directions with respect to the longitudinal axis of the piston in the range from about 15 degrees to about 75 degrees (eg, in the range from about 30 degrees to about 60 degrees, about 45 degrees). It has chamfered surfaces at the leading front end and the trailing rear end. Piston head 434A is mechanically coupled to cassette 312 in much the same way as piston head 334A described above. In particular, the piston head 434A is advanced into the dome-shaped member 361A, and the protrusions 449A and 453A of the spring fingers 445A and 447A come into contact with the enlarged head 372A of the peg 368A, and the protrusions 449A, The angled orientation of the front surface of the 453A causes the spring fingers 445A, 447A to deflect radially outward. The spring fingers 445A, 447A are formed by the enlarged head 372A of the peg 368A sliding forward beyond the protrusions 449A, 453A and between the spring fingers 445A, 447A behind the protrusions 449A, 453A. Spread and leave enough distance to slide into the space.

To disconnect the piston head 434A from the peg 368A after treatment, the piston head 434A is retracted into the PD circulator. When the piston head 434A is retracted, the resistance of the membrane 140 pulling the dome-shaped member 361A reaches a position where it is greater than the force required to spread and release the fingers 445A, 447A. At this position, as the piston head 434A continues to retract, the chamfered rear surfaces of the protrusions 449A and 453A slide axially along the enlarged head 372A of the pegs 368A of the cassette 312 of the spring fingers 445A and 447A. This allows the spring fingers 445A, 447A to spread apart, allowing the pegs 368A to be released from the space behind the protrusions 449A, 453A of the fingers 445A, 447A.

The cassette interface 110 of the PD circulation device 102 includes a positioning pin 148 that helps ensure that the dome-shaped member of the cassette and the pistons 133A, 133B are aligned when the cassette is positioned within the cassette compartment 114. Although described as, other structures or techniques may also be used to ensure this alignment. In some implementations, for example, the cassette contacts the PD circulator door with a hollow protrusion of the cassette disposed in the recess of the PD circulator door, and the cassette is a retainer attached to the door. -The clip holds it in this position. When the door is closed, the position of the piston of the PD circulation device and the position of the dome-shaped member of the cassette are aligned.

Each door 108 of the PD circulation device described above is described as comprising an inflatable pad capable of pressing the cassette against the cassette interface when inflated, whereas the inflatable pad is an alternative to the cassette. The spine of the cassette interface so that the interface can be moved towards the door 108 and the cassette in between can be compressed. Can be positioned later. Similarly, as an alternative to the inflatable pad, use any of the various mechanisms that can be manipulated to move the surface of the door 108 towards the cassette interface or the cassette interface towards the surface of the door 108. Can be done.

The PD circulator door 108 described above is illustrated as being positioned in front of the PD circulator, but the doors are instead placed in various other locations on the PD circulator. It can also be positioned. For example, it is possible to position the door on the top surface of the PD circulation device so that the cassette slides into the cassette compartment in a nearly horizontal orientation rather than a nearly vertical orientation. In some implementations, the door and the cassette interface of the PD circulation device are positioned at an angle of about 10 to about 35 degrees with respect to the vertical when the PD circulation device is placed in a horizontal plane. It has been found that this configuration facilitates the user to load the cassette into the cassette compartment.

The cassette described above has two pump chambers, but the cassette can have more or less pump chambers instead. Each of the cassette pump chambers described above has been described as having a fluid inlet port and a fluid outlet port, but in some implementations the pump chamber is simply used as both an inlet and an outlet. It has one port. In such an implementation, the inflatable valve members of the PD circulation device acting on the valve portion of the cassette are actuated and stopped in a slightly different order, which draws the fluid from the desired location into the pump chamber and then. , Can be forced out of the pump chamber to the desired location.

While some PD circulators described above have been described as having a touch screen and associated buttons, PD circulators have alternative or, in addition, other types of screen and user data entry. Can be equipped with a system. In some implementations, for example, the circulator is a button configured on the console adjacent to the display screen (eg, feather touch). It has a display screen with buttons)). Some buttons can be arranged and configured to align with the operation options displayed on the screen during use, which allows the user to align the desired operation option with the button aligned with that operation option. Can be selected by pressing. Additional buttons in the form of arrow buttons can also be provided to allow the user to navigate different display screens and / or different items displayed on a particular screen. Other buttons may take the form of a numeric keypad that allows the user to enter a number, for example, to enter an operating parameter. Select or enter buttons to allow the user to select behavior options that the user navigated using the arrow keys and / or to allow the user to enter values that the user has entered using the numeric keypad. Can also be provided.

The mechanically connectable piston heads and cassettes described above are described as being part of a PD system, but these types of piston heads and cassettes are of various other types. Can be used in medical fluid pumping systems. Other examples of medical fluid pumping systems that can use the piston heads and cassettes described herein include hemodialysis systems, hemoperfusion systems, and intravenous injection systems.

Similarly, many of the above systems are described as being used to pump dialysis solutions, but other types of dialysis fluids can also be pumped through the cassette. For example, in the case of a cassette used with a hemodialysis machine, blood can be pumped through the cassette. In addition, priming fluids such as saline can also be pumped through the cassette using the various different systems and techniques described above. Similarly, depending on the type of medical fluid pumping device in which the cassette is used as an alternative to dialysis fluid. , Various other types of medical fluids can be pumped through the cassettes described above.