Extracorporeal circuit

An extracorporeal circuit, which makes it possible to efficiently collect priming solution by displacing the priming solution with blood after the priming solution is fed to the extracorporeal circuit to prime the extracorporeal circuit, includes a circuit body including first and second tubes, a feed bag that feeds the priming solution, a blood reservoir in which a liquid is temporarily stored, a third tube that branches out from the middle of the first tube, and a collection bag which communicates with the third tube and into which the priming solution is collected through the third tube. After the priming solution is fed from the feed bag to prime at least a housing, when the priming solution in the housing is displaced by blood, the priming solution in the housing is transferred and collected in the collection bag due to a height difference between the liquid level and the collection bag.

This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/946,197 filed on Jun. 26, 2007, the entire content of which is incorporated herein by reference. This application is also based on and claims priority to Japanese Application No. 2007-110651 filed on Apr. 19, 2007, the entire content of which is incorporated herein.

BACKGROUND DISCUSSION

The present invention generally relates to a blood circulation system. More specifically, the invention pertains to an extracorporeal circuit.

TECHNOLOGICAL FIELD

U.S. Pat. No. 6,908,446 describes a known extracorporeal circuit that extracorporeally circulates blood. The extracorporeal circuit includes a venous line and an arterial line that are coupled to a patient, a blood reservoir connected on a downstream side of the venous line, an oxygenator connected on an upstream side of the arterial line, and a linkage line linking the blood reservoir and oxygenator.

When the extracorporeal circuit (hereinafter simply referred to as a circuit) described in this patent is used to extracorporeally circulate blood, a priming solution (for example, physiological saline) is fed to the circuit in order to prime the circuit. Thereafter, extracorporeal circulation is performed. When this kind of operation is performed, blood is diluted with the priming solution (hemodilution).

In recent years, a technique has been adopted prior to extracorporeal circulation involving collecting the priming solution as much as possible to hinder hemodilution. The technique is normally referred to as retrograde autologous priming (RAP). This RAP technique involves connecting to the circuit in advance a collection bag into which the priming solution is collected. In this state, blood is drawn from a patient to the circuit in a direction opposite to the direction of the normal flow of blood during extracorporeal circulation, and is used to thrust the priming solution in the circuit into the collection bag.

However, when the priming solution is merely thrust with regurgitant blood, the priming solution may not be fully collected in the collection bag, though it depends on the circuitry of the extracorporeal circuit. Therefore, as an auxiliary way for fully thrusting the priming solution, a pump may be adopted or an additional line may be included. This makes the circuitry complex. Consequently, manipulations to be performed on the circuit from the instant of priming to the instant of extracorporeal circulation (for example, starting or stopping of the pump and switching of lines in the circuit) become complex. Accordingly, it is difficult to quickly achieve the RAP, that is to quickly collect the priming solution.

SUMMARY

According to one aspect, an extracorporeal circuit for extracorporeally circulating blood comprises a circuit body for circulating liquid through a plurality of extracorporeal circuit components, the circuit body comprising a plurality of tube segments, a blood reservoir comprising one of the extracorporeal circuit components, the blood reservoir possessing an interiorly located storage chamber in which a liquid is received, a tube communicating with a first one of the tube segments, the tube possessing a lower end positioned in the storage space of the blood reservoir adjacent the bottom surface of the storage chamber, and a branch line branching out from an intermediate portion of the first tube segment. In addition, a collection container is provided and communicates with the branch line and into which liquid in the storage chamber flows by way of the branch line.

According to another aspect, an extracorporeal circuit for extracorporeally circulating blood comprises a circuit body comprised of a plurality of circuit tubes including a first circuit tube, wherein the first circuit tube is comprised of a plurality of tube segments including a first tube segment constituting a venous line adapted to be connected to a vein of a patient during extracorporeal circulation and a second tube segment constituting an arterial line adapted to be connected to an artery of the patient during extracorporeal circulation. The extracorporeal circuit also includes a blood reservoir connected to the first tube segment and having an interiorly located storage chamber for temporarily storing liquid, a pump connected to the reservoir and positioned along the circuit body to convey liquid in the circuit body, an oxygenator connected to the second tube segment and configured to perform gas exchange on blood flowing through the circuit body, and a priming solution feeding unit containing priming solution and in communication with the blood reservoir. A reservoir tube has one end communicating with the first tube segment constituting the venous line and an opposite end which is open and which is positioned adjacent a bottom of the storage chamber, while a branch line communicates with and branches out from an intermediate portion of the first tube segment constituting the venous line. The extracorporeal circuit also includes a collection container communicating with the branch line and into which the priming solution in the storage chamber is collected by way of the branch line. After the priming solution is fed from the priming solution feeding unit to the storage chamber to prime at least the storage chamber, the priming solution in the storage chamber is displaced by blood and is transferred to the collection container due to a difference in height of liquid in the storage chamber relative to liquid in the collection container.

According to a further aspect, a method of using an extracorporeal circuit comprises introducing a priming solution into an extracorporeal circuit to prime the extracorporeal circuit before introducing a patient's blood into the extracorporeal circuit, and with the introduction of the priming solution into the extracorporeal circuit introducing the priming solution into the interior of a blood reservoir constituting a part of the extracorporeal circuit. The extracorporeal circuit also comprises a circuit tube connected to the interior of the blood reservoir, a collection bag, and a branch line having one open end opening into the collection bag and an opposite end connected to and communicating with an intermediate portion of the circuit tube. The method further comprises positioning the collection bag relative to the blood reservoir so that the one open end is located elevationally lower than a level of the priming solution in the blood reservoir, and permitting the priming solution in the interior of the blood reservoir to flow into the collection bag by way of the branch line under a siphon principle.

DETAILED DESCRIPTION

FIGS. 1-11illustrate a first embodiment of the circuitry of an extracorporeal circuit as disclosed herein.FIG. 12is a side view of the blood reservoir included in the extracorporeal circuit shown inFIG. 1. For the sake of convenience, the part of the blood reservoir shown in the upper part ofFIG. 12is called the upper part of the blood reservoir and the part of the blood reservoir shown in the lower part ofFIG. 12is called the lower part of the blood reservoir. This same nomenclature also applies to the illustrations inFIG. 13andFIG. 14.

Referring toFIGS. 1-11, an extracorporeal circuit1shown inFIG. 1circulates blood B and is configured to perform retrograde autologous priming (RAP). RAP is a technique for hindering hemodilution by collecting a priming solution P as much as possible before normal extracorporeal circulation of blood B (which may be simply referred to as extracorporeal circulation) is performed (seeFIG. 11) after the extracorporeal circuit1is primed (i.e., filled with the priming solution P).

As shown inFIG. 1, the extracorporeal circuit1includes a circuit body9composed of four transparent tubes (circuit tubes)90,92,93,96, a blood reservoir3connected to several of the tubes, a pump4for drawing blood, and an oxygenator5. Moreover, the extracorporeal circuit1includes, in addition to these components, a feed bag6from which a priming solution P is fed, a transparent tube20linking the feed bag6and the blood reservoir3, a transparent tube (branch line or branch tube)10that branches out from a tube91included in the circuit body9, a collection bag7coupled to the tube10, a collection bag supporting device8that supports the collection bag, and two clamps30to be used to open or close the tube96and the tube10respectively. The illustrated and described embodiment of the circuit shown inFIG. 1, prior to use, is a closed system.

In the present embodiment, for convenience' sake, the portion of the tube (first tube)90extending in an up-and-down direction on the blood reservoir3side (right side) of the tube90inFIG. 1is referred to as the tube or tube segment91. The portion of the tube90extending in the up-and-down direction on the oxygenator5side (left side) of the tube90inFIG. 1is referred to as the tube or tube segment94. The portion of the tube90extending in the right-and-left direction between the tube91and the tube94inFIG. 1is referred to as the tube or tube segment95. Thus, as will become more apparent from the description below, the tube90is comprised of a first tube segment91forming a venous line, a second tube segment94forming an arterial line, and a third tube segment95interconnecting or communicating with both the first and second tube segments91,94.

The blood reservoir3shown inFIG. 12is used to temporarily store a liquid in the extracorporeal circuit1(for example, blood B drawn from the large vein or a priming solution P). The blood reservoir3includes a housing33composed of a housing body31and a cover32. A liquid storage space34in which a liquid (blood) is received and temporarily stored is interiorly located within the housing33.

The housing body31is shaped like a box having a projection311jutting or projecting downward in the left part ofFIG. 12. Thus, the interior of the housing body31includes a larger upper portion (i.e., an upper portion of larger cross-sectional area) and the projection311defining a lower portion of smaller cross-sectional area. The housing body31thus includes a shelf313between the larger upper portion and the smaller lower portion. A tubular connecting port35communicating with the liquid storage space34is formed at the lower end of the projection311.

The cover32is engaged with the upper end of the housing body31so that it covers the upper opening of the housing body31. The tubular connecting ports36,37are formed at predetermined positions in the cover32.

The connecting ports35-37are coupled (connected) as mentioned below in the extracorporeal circuit1. As shown inFIG. 11, the tube91that serves as a venous line during extracorporeal circulation is coupled to the connecting port37. Namely, blood from a patient flows through the connecting port37and into the blood reservoir during extracorporeal circulation.

The tube20is coupled (connected) to the connecting port36. The blood reservoir3and the feed bag6are linked by the tube20, and the priming solution P is fed from the feed bag6to the blood reservoir3.

The tube92is coupled (connected) to the connecting port35. The blood reservoir3and the pump4are linked by the tube92. When the pump4is started, liquid (blood B or priming solution P) is fed from the blood reservoir3to the oxygenator5.

The blood reservoir3having the foregoing structure is used in a posture having the connecting ports36,37located vertically upward and above the connecting port35which is located vertically downward or vertically lower than the connecting ports36,37.

Moreover, a tube (reservoir tube)381is coupled to the connecting port37and is positioned inside the housing33. This allows the tube381to communicate with the tube91on the upper side thereof via the connecting port37. Moreover, the lower end381aof the tube381is open to the interior of the reservoir. As shown inFIG. 12, the lower end381aof the tube381is located near the bottom312of the projection311, and faces the bottom312or bottom surface of the downward projection311. The lower end381aof the tube381is vertically positioned between the bottom surface312of the downward projection311and the shelf313, with the lower end381aof the tube381being preferably vertically closer to the bottom surface312of the downward projection311than the shelf313of the housing body31.

A filter member382shaped like a sac and sheathing or covering the tube381is disposed outside the tube381. The upper end of the filter member382is supported by the cover32.

The filter member382is configured to remove foreign matter or bubbles from blood. The material of the filter member382is a porous material that is fully permeable to blood.

Moreover, a filter member392also shaped like a sac is disposed on the housing33side of the connecting port36. The upper end of the filter member392is supported by the cover32.

The filter member392is configured to remove foreign matter or bubbles from the priming solution P, transfusional blood, or a replacement fluid. The material of the filter member382is a porous material that is fully permeable to the priming solution or blood.

Moreover, an antifoaming member (not shown) is interposed between the tube381and filter member382and disposed inside the filter member392.

The material of the tube381is not limited to any specific material. For example, polycarbonate, polypropylene, polyvinyl chloride, or any other polymeric material will do.

Examples of the porous material to be used to fabricate the filter members382,392include a mesh-type material, a woven fabric, or a nonwoven fabric. These materials may be used individually or may be combined.

Projecting out from the oxygenator5are several ports, including a blood inflow port512via which blood flows into the oxygenator5, a blood outflow port513via which blood flows out of the oxygenator5, a gas inflow port514, a gas outflow port, a heat carrier inflow port515, and a heat carrier outflow port516. In addition, a hollow fiber membrane bundle in which numerous hollow fiber membranes having a gas exchange capability are integrated is stored in the oxygenator5. Further, a filter member having the capability to trap bubbles may be stored to lie on the periphery of the hollow fiber membrane bundle.

The pump4transfers blood within the extracorporeal circuit1(circuit body9). The pump4, preferably in the form of a centrifugal pump, includes a rotator that rotates under the control of a control device to which the pump is operatively connected. The pump4can adjust the quantity of transferred blood according to the number of rotations of the rotator.

The pump4is interposed between the blood reservoir3and the oxygenator5. The pump4is coupled o connected to both the tube92, which is connected to the blood reservoir3, and the tube93, which is connected to the oxygenator5as shown in, for example,FIG. 1.

As mentioned above, the circuit body9includes the tubes90,92,93,96. The tube90may be divided into three regions, namely tubes91,94,95. As shown inFIGS. 1-3, the circuitry defining the extracorporeal circuit1includes the tube91serving as a venous line during extracorporeal circulation, the blood reservoir3, the tube92, the pump4, the tube93, the oxygenator5, the tube94serving as an arterial line during extracorporeal circulation, and the tube95serving as a linkage line linking the ends of the tubes91,94. These parts of the circuit are arranged and connected in the order described.

The tube95is included in the extracorporeal circuit1until the extracorporeal circuit1is primed with the priming solution P (see, for example,FIG. 3). Thereafter, as shown inFIG. 5, as well asFIGS. 6-11, when blood B is extracorporeally circulated, the center part of the tube95that includes a loop951and the part of the tube95on the side of the tube94are cut out and removed, and the remaining parts of the tube95are coupled to indwelling venous-line and arterial-line catheters of a patient. In this state, the blood B is extracorporeally circulated.

Moreover, in the extracorporeal circuit1, an intermediate portion (e.g., middle) of the tube91and an intermediate portion (e.g., middle) of the tube94are linked by the tube (second tube)96. The tube96serves as a recirculation line when the extracorporeal circuit1is used to re-circulate blood B.

The tube10is coupled to the tube91at a region between the part to which the tube96is coupled to the tube91and the part to which the tube96is coupled to the blood reservoir3. The tube10is coupled to the collection bag7which will be described in more detail later. The priming solution P is collected into the collection bag7by way of the tube10.

The clamps30are attached to an intermediate portion of the tube96and an intermediate portion of the tube10. The clamps30operate to press and close the tubes externally. Consequently, the tubes10,96are brought to a closed state. When the pressing and closing by the clamps30is lifted or removed (i.e., when the clamps are opened), the tubes96,10are brought to an open state.

The feed bag6is used to feed the priming solution P. The priming solution P is poured to such an extent that it can be fed to the entire extracorporeal circuit1. Assuming that the lengths of the tubes91,94which occupy a majority of the circuit body9range from, for example, 100 cm to 200 cm, the quantity of the poured priming solution P preferably ranges from 750 ml to 1500 ml.

The feed bag6is connected to the blood reservoir3at a position vertically above the tube20. When the priming solution P flows into the liquid storage space34of the housing33of the blood reservoir3, bubbles which may have flowed in together with the priming solution P are trapped by the filter member392. Consequently, the bubbles can be inhibited or prevented from flowing out to the downstream side of the filter member392.

Examples of suitable priming solution P include physiological saline or a lactated Ringer's solution.

The collection bag7is used to collect the priming solution P. The collection bag7is, similar to the feed bag6, produced by fusing (heat fusion or high-frequency fusion) or bonding the perimeters of layered sheets, made of a soft resin such as polyvinyl chloride and flexible, in the form of a sac. The priming solution P is stored in spaces between the sheet layers. The volume of the collection bag7is nearly equal to or slightly larger than the volume of the feed bag6.

The shape of the collection bag7is not limited to any specific shape. However, when the priming solution P is poured into the collection bag7, that is, when the collection bag7is dilated, the collection bag should preferably be elongated.

The collection bag7may be placed so that the longitudinal direction of the bag is nearly parallel to a horizontal direction or will extend in a vertical direction. In the present embodiment, the collection bag7is placed so that the longitudinal direction thereof will extend nearly in the vertical direction.

Moreover, the open end101of the tube10(i.e., the liquid inflow port of the collection bag7) should be located in the upper portion of the collection bag7. The opening direction of the open end101should be a horizontal direction or a bit upward with respect to the horizontal direction. When the open end101of the tube10opens downward, if a liquid drips from the open end101, air may enter the tube10by a volume equivalent to the quantity of the liquid. That is, if the open end101of the tube10is opened in the downward direction and a liquid drop falls from the open end101of the tube10, an air drop generally equal in volume to the quantity or volume of the liquid drop may enter the tube, resulting in an air bubble in the tube. To avoid this potential problem, the opening direction in which the open end101of the tube10opens should preferably be restricted as mentioned above. As long as the opening direction is horizontal or upward, the open end101side of the tube10may invade into the collection bag7from the side wall of the collection bag or the top portion (upper wall) of the collection bag.

Moreover, when the collection bag7is used, the collection bag7is supported by (placed on) the collection bag supporting device8. The collection bag supporting device8includes a placement unit81on which the collection bag7is placed, and a link mechanism82serving as a height adjusting means for adjusting the height of the placement unit81.

In the illustrated embodiment, the placement unit81is in the form of a flat plate. The collection bag7is placed on the placement unit81.

The link mechanism82includes two elongated members83a,83bsupported to pivot on the center part831. The upper end832of the elongated member83ais supported so that it can pivot with respect to the placement unit81, and the upper end832of the elongated member83bis engaged with an engagement piece84disposed at a lower side of the placement unit81. The engagement piece provides a mechanism permitting adjustment of the upper end832of the elongated member83brelative to the placement unit81. For example, three recesses (concave parts)841are formed in the engagement piece84. By engaging the upper end832of the elongated member83bin a selected one of the recesses841, the height of the placement unit81can be appropriately set and adjusted.

By adjusting the height of the placement unit81, the height of the liquid level L1in the blood reservoir3can be adjusted. In other words, the height of the open end101of the tube10in the collection bag7can be set to a target height of the liquid level L1(shown inFIG. 11) in the blood reservoir3. Consequently, the priming solution P can be collected based on the principle of a siphon that will be described later.

Next, the operation of the extracorporeal circuit1will be described below.

[1] In an initial state shown inFIG. 1, the pump4is stopped. The clamp30attached to the tube96is left open, and the clamp30attached to the tube10is closed.

Three forceps40are attached to, or provided at spaced apart positions along, the tube91in the initial state. With respect to these three forceps40, the positions (attached positions) of two of the forceps40along the tube are, in the circuitry shown inFIG. 1, between the joint where the tube91and the tube95join each other, and the joint where the tube91and tube96join each other. Stated differently, the two forceps40are positioned along the tube91at a position near the tube95(on the side of the tube95) and at a position near the tube96(on the side of the tube96) respectively. Moreover, the position (attached position) of the third forceps40is between the joint at which the tube91and the tube96join each other and the joint at which the tube91and the blood reservoir3(connecting port37) join each other. Hereinafter, the parts of the tube91to which the three forceps40are attached are referred to as the forceps-attached part911, the forceps-attached part912, and the forceps-attached part913in that order from the tube95side thereof (the upper side inFIG. 1).

Two additional forceps40are attached to, or provided at spaced apart positions along, the tube94in the initial state. The attached positions of these two additional forceps40along the tube94are, in the circuitry shown inFIG. 1, between the joint where the tube94and the tube95join one another and the joint where the tube94and the tube96join each other. That is, the two additional forceps are positioned along the tube94at a position near the tube95(on the side of the tube95) and at a position near the tube96(on the side of the tube96) respectively. Hereinafter, the portions of the tube94to which the forceps40are attached are referred to as the forceps-attached part941and the forceps-attached part942in that order from the tube95side thereof (the upper side inFIG. 1).

The collection bag7is placed on the collection bag supporting device8. The height at which the collection bag7is disposed is a height permitting the height of the open end101of the tube10in the collection bag7to square with (be even with or at the same height as) the target height of the liquid level L in the blood reservoir3(shown inFIG. 11). In the collection bag supporting device8, the engagement of the elongated member83bof the link mechanism32with the engagement piece84is adjusted so that the collection bag will be disposed at the desired height.

When the height of the collection bag7is designated as mentioned above, the priming solution P can be readily and quickly collected into the collection bag7according to the principle of a siphon to be described later.

[2] Thereafter, the tube20is coupled to the feed bag6. Consequently, the priming solution P in the feed bag6flows into the blood reservoir3by way of the tube20due to a difference in height, and further flows in the direction of the arrow shown inFIG. 2. At this time, the pump4is started.

In other words, when the tube20is coupled to the feed bag6, the priming solution P in the feed bag6sequentially passes through the tube20and the connecting port36of the blood reservoir3and is introduced into the housing33. The priming solution P introduced into the housing33flows out through the connecting port35. The priming solution P sequentially passes through the tube92, pump4, and the tube93, and is fed to the oxygenator5. The priming solution P further passes through the oxygenator5and flows into the tube94. The priming solution P in the tube94is divided into two portions, one portion flowing into the tube96from an intermediate portion of the tube94and another portion continuing to flow in the tube94toward the end (downstream side) of the tube94in a direction towards the tube95.

The priming solution P that flows into the tube96from the tube94sequentially passes through the tube96and the tube91, and once again flows into the blood reservoir3. In the tube10, the air in the tube is displaced by the priming solution. The tube10is filled with the priming solution up to the position of the clamp30. Moreover, the priming solution P that heads for or flows toward the tube95sequentially passes through the tube95and the tube91, merges into the priming solution P, which has passed through the tube96, in the intermediate portion of the tube91, and once again flows into the blood reservoir3. The liquid level L1of the priming solution P in the blood reservoir3lies at a position higher than the position of the open end101of the tube10.

Through the foregoing process, the entire extracorporeal circuit1is filled with the priming solution P, that is the entire extracorporeal circuit1is primed. Moreover, in the extracorporeal circuit1, the liquid level L1of the priming solution P in the blood reservoir3is set to a position above the lower end381aof the tube381as seen inFIGS. 2-11. Consequently, when the priming solution P in the blood reservoir3is collected, the principle of a siphon can be utilized.

Moreover, as mentioned above, the tube10is occluded by the clamp30. Therefore, the priming solution P in the extracorporeal circuit1can be reliably prevented from being unexpectedly collected into the collection bag7.

In the state shown inFIG. 2, the priming solution P in the projection311of the blood reservoir3, that is the quantity of priming solution equivalent to a depth from the liquid level L1shown inFIG. 2to the liquid level L1shown inFIG. 3represents an excess. At the next step [3], the excessive quantity is collected in the collection bag7.

[3] As shown inFIG. 3, the clamp30attached to the tube96is closed. The forceps40are attached to the forceps-attached part912of the tube91, and the forceps40are attached to the forceps-attached part942of the tube94. At this time, the pump4is stopped.

Thereafter, the clamp30attached to the tube10is opened. This causes the tube91and collection bag7to communicate with each other by way of the tube10. The priming solution P is transferred and collected in the collection bag7as described below due to a difference in height of the liquid level L1in the blood reservoir3from the liquid inflow port of the collection bag7(the open end101of the tube10), that is due to the principle of a siphon. The open end101of the tube10through which liquid flows into the collection bag7is located at the target height of the liquid level L1.

When the clamp30of the tube10is opened, the priming solution P in the tube10flows into the collection bag7. When the priming solution P begins flowing into the collection bag7, the priming solution P in the blood reservoir3passes through the tube381accordingly, and is then introduced (thrust) into the tube91. The priming solution P introduced into the tube91flows into the collection bag7by way of the tube10. This phenomenon persists until the liquid level L1in the blood reservoir3reaches (is lowered to) the same height as the height of the open end101of the tube10in the collection bag7(the principle of a siphon). Consequently, the excessive quantity of priming solution P in the blood reservoir3can be readily and quickly collected.

As mentioned above, in the extracorporeal circuit1, once the height of the open end101of the tube10in the collection bag7is appropriately adjusted, a quantity of the priming solution P determined by this height flows into the collection bag7. Consequently, when the extracorporeal circuit1is manipulated, an operator need not be conscious of whether the position of the liquid level L1in the blood reservoir3is lowered below a predetermined position.

[4] After the priming solution P is collected, the clamp30attached to the tube10is reclosed as shown inFIG. 4, meaning that the clamp30is once again closed. Also, the forceps40are attached to the forceps-attached part911of the tube91, and the forceps40are attached to the forceps-attached part941of the tube94.

In this state, the tube95is cut as mentioned above, and coupled to an arterial-line catheter that is one of the two indwelling catheters of a patient.

[5] In the state shown inFIG. 4, two forceps40are detached from the tube94. At this time, blood B flows from the patient to the tube94in the direction of the arrow inFIG. 5due to blood pressure. The flow of the blood B is opposite to that in normal extracorporeal circulation.

The blood B flowing into the tube94sequentially passes through the oxygenator4, tube93, pump4, and tube92, and flows into the projection311of the housing33through the connecting port35of the blood reservoir3. Due to the blood B, the priming solution P in the tube94, oxygenator4, tube93, pump4, and tube92is thrust into the housing33. In other words, the priming solution P in the tube94, oxygenator4, tube93, pump4, and tube92is displaced by the blood B.

Moreover, when the blood B flows into the projection311, the blood B is mixed with the priming solution P in the projection311. Namely, part of the priming solution P in the projection311is colored in red that is lighter than the color of the blood B. InFIG. 5, a mixture M having the priming solution P and blood B mixed together is shown positioned between the vertically higher priming solution P and the vertically lower blood B in the projection311.

[6] After the coloring is recognized, the forceps40are once again attached to the forceps-attached part942of the tube94as shown inFIG. 6. Consequently, the flow of the blood B into the tube94ceases. Accordingly, the rise of the liquid level L1in the blood reservoir3stops.

In the state shown inFIG. 6, the priming solution P in the tube94, the oxygenator5, the tube93, the pump4, and the tube92is reserved in the blood reservoir3. Further, the priming solution P is left intact in a range from the tube381in the blood reservoir3to the part of the tube91to which the tube10is coupled. At the next step [7], the priming solution is collected in the collection bag7.

[7] The clamp30attached to the tube10as shown inFIG. 6is reopened as illustrated inFIG. 7. Consequently, the priming solution P (including the mixture M) in the blood reservoir3, and the priming solution P in the range from the tube381in the blood reservoir3to the part of the tube91to which the tube10is coupled flow into the collection bag7by way of the tube10based on the principle of a siphon similar to the process [3] described above. The inflow of the priming solution P continues until the liquid level L1in the blood reservoir3comes to the same height as the height of the open end101of the tube10in the collection bag7.

As mentioned above, at the step [7], the priming solution P can be readily and quickly collected by performing the simple manipulation of opening the clamp30.

[8] After the inflow of the priming solution P ceases, the clamp30attached to the tube10is closed again as shown inFIG. 8. Thereafter, the forceps40are detached from the forceps-attached part942of the tube94.

In this state, blood B flows from the patient in the direction of the arrow inFIG. 8due to blood pressure. Consequently, in the extracorporeal circuit1, the tube94, the oxygenator5, the tube93, the pump4, the tube92, and the blood reservoir3are filled with the blood B as depicted inFIG. 8.

[9] After a predetermined quantity of the blood B is poured into or enters the blood reservoir3, the forceps40are reattached to the forceps-attached part942of the tube94. Consequently, the inflow of the blood B to the tube94ceases. Moreover, the forceps40are attached to the forceps-attached part913of the tube91. Thereafter, the tube91is coupled to the indwelling venous-line catheter of the patient.

In this state, the clamp30attached to the tube10is reopened as shown inFIG. 9.

[10] In the state shown inFIG. 9, the forceps40are detached from the forceps-attached parts911,912of the tube91. At this time, the blood B flows from the patient into the tube91due to a blood pressure. The blood B having flowed into the tube91thrusts the priming solution P in the tube91in the direction of the arrow inFIG. 10. Consequently, the priming solution P in the tube91is collected in the collection bag7by way of the tube10.

[11] After the priming solution P in the tube91is displaced by the blood B, the clamp30attached to the tube10is re-closed. Thereafter, both the forceps40attached to the forceps-attached part913of the tube91and the forceps40attached to the forceps-attached part942of the tube94are detached.

In this state, the blood B flows in the direction of the arrow inFIG. 11due to a difference in height and a patient's blood pressure. Moreover, at this time, the pump4is restarted.

Specifically, when the pump4is started, the blood B drawn from the patient passes through the tube91(venous line), and flows into the blood reservoir3. In the blood reservoir3, bubbles are removed from the blood B owing to the operation of the filter member382. The blood B having bubbles removed therefrom flows out of the connecting port35of the blood reservoir3, passes through the pump4, and is fed to the oxygenator5. In the oxygenator5, the blood B is subjected to gas exchange (oxygenated and decarboxylated). The blood B having been subjected to gas exchange passes through the tube94(arterial line) and returns to the patient.

Owing to the above operation, after the extracorporeal circuit1is primed, when the priming solution P is displaced by the blood B, the priming solution P can be readily and quickly collected by performing the relatively simple operation of manipulating the clamp30attached to the tube10. Consequently, the procedure can quickly proceed to the extracorporeal circulation step (step [11]) at which the extracorporeal circuit1is employed or put into operation.

Moreover, the extracorporeal circuit1can thrust the priming solution P into the collection bag7using the blood B, that is the system can perform RAP. The blood B in the extracorporeal circuit1can be prevented from being diluted with the priming solution P.

Moreover, in the extracorporeal circuit1, in the state shown inFIG. 11, after the forceps40are attached to the forceps-attached part912of the tube91and the forceps-attached part942of the tube94respectively, the clamp30of the tube96can be opened. In this case, the blood B coming out of the oxygenator5sequentially passes through the tube96(recirculation line) and blood reservoir3, and then returns to the pump4. The blood B is therefore repeatedly circulated (re-circulated) over an annular path including the pump4and oxygenator5.

FIG. 13is a perspective view of a blood reservoir and a collection bag included in an extracorporeal circuit according to a second embodiment.

The second embodiment will be described below, primarily with reference to features in this embodiment that differ from the features in the first embodiment. Features in this second embodiment that are similar to those in the first embodiment are designated by common reference numerals and a detailed description of such features will not be repeated here.

The second embodiment is identical to the first embodiment except that the structures of the blood reservoir and the collection bag are different.

A collection bag7A of an extracorporeal circuit1A shown inFIG. 13is produced by fusing (or bonding) the perimeters of layered sheets, which are flexible and made of a soft resin such as polyvinyl chloride, in the form of a sac, and then forming two holes71in the fused perimeters. The holes71are formed in spaced apart relation to one another and are located in the upper part of the collection bag7A in a use state of the collection bag7A.

A holding member50that holds the collection bag7A (on which the collection bag is hung) is disposed on the flank of the blood reservoir3A (the housing33). The holding member50includes a plate-shaped support element501and two hooks502borne on and extending outwardly away from the face of the support plate501.

The support element501is made of the same material as, for example, that of the housing body31of the blood reservoir3A. A double-sided adhesive tape is bonded to the back of the support plate501. Owing to the presence of the double-sided adhesive tape, the holding member50can be attached to or detached from the blood reservoir3A. The height at which the holding member50is disposed on the blood reservoir3A can be changed (as indicated by the two positions shown in FIG.13—the solid line position and the position represented by alternating long and two short dash lines).

The hooks502are L-shaped and made of a metallic material, for example stainless steel. The hooks502are inserted into the respective holes71in the collection bag7A, whereby the collection bag7A is hung on the support element (the hooks502of the supporting element) while being used.

The adhesive strength of the double-sided adhesive tape is set to such a level that when the collection bag7A is hung on the holding member50, even if the priming solution P is poured into the collection bag7A, the holding member50will not come off the blood reservoir3A.

As mentioned above, in the extracorporeal circuit1A, the holding member50is designed so that the disposed height of the collection bag7A on the blood reservoir3A can be adjusted. Consequently, a quantity of the priming solution P collected into the collection bag7A can be appropriately designated according to the situation.

FIG. 14is a perspective view of a blood reservoir and a collection bag included in an extracorporeal circuit according to a third embodiment.

The third embodiment will be described below, primarily with reference to features in this embodiment that differ from the features in the second embodiment. Features in this third embodiment that are similar to those in the second embodiment are designated by common reference numerals and a detailed description of such features will not be repeated here.

This embodiment is identical to the second embodiment except for differences in the structure of the blood reservoir.

A holding mechanism60that holds the collection bag7A (on which the collection bag7A is hung) is disposed on the flank of a blood reservoir3B (housing33) included in an extracorporeal circuit1B shown inFIG. 14. The holding mechanism60includes a column601having the lower end thereof borne by the blood reservoir3B, a moving member602that is movable in the longitudinal direction of the column601, two hooks603borne by and extending outwardly away from the moving member602, and a setscrew (locking member)604that locks the moving member602to the column601. The column601has a cylindrical shape.

The moving member602is formed as an elongated member. One end of the elongated member forming the moving member602has a hole602athrough which the column601penetrates. A female screw that reaches (i.e., communicates with) the hole602ais threaded in the flank of the moving member602.

The hooks603are L-shaped, and made of a metallic material, for example stainless steel. Moreover, the hooks603are disposed is spaced apart relation to one another in the longitudinal direction of the moving member602. When the hooks603are inserted into the holes701in the collection bag7A, the collection bag7A can be used while being hung on the blood reservoir (or abutting against the blood reservoir).

The setscrew604includes a male screw portion604a, and a head portion604battached to one end of the male screw portion604a. The setscrew604has the male screw portion604thereof meshed with the female screw threaded in the moving member602, and has the other end of the male screw portion604thereof engaged with the periphery of the column601. Consequently, the moving member602can be locked to the column601(i.e., the vertical position of the moving member602can be fixed relative to the column601). Thus, the collection bag7A can be held at a predetermined position (height).

Moreover, when the setscrew604is loosened, the moving member602is unlocked and can be moved. Consequently, the disposed height of the collection bag7A on the blood reservoir3B can be changed.

As mentioned above, in the extracorporeal circuit1B, the holding mechanism60is designed so that the disposed height of the collection bag7A on the blood reservoir3A can be adjusted by moving the moving member602. Consequently, the quantity of priming solution P to be collected into the collection bag7A can be appropriately designated according to the situation.

Moreover, since the column601has a cylindrical shape, the moving member602unlocked from the setscrew604can be turned on (i.e., can rotate relative to) the axis of the column601. Consequently, the orientation of the held collection bag7A can be varied depending on, for example, the standing position of a user. Eventually, the state of the priming solution P being collected into the collection bag7A can be readily discerned (checked).

The invention here is not limited to the embodiments of the extracorporeal circuit which are shown in the drawings and described above. The components of the extracorporeal circuit may be replaced with alternative features which exhibit the same or similar functions. In addition, components or features beyond those shown and described here can be provided.

The extracorporeal circuit may be a combination of two or more of the aforesaid embodiments (constituent features).

Also, the feed bag and collection bag are not limited to those made of a soft resin material but may be bags made of a hard resin material such as polypropylene. Additionally, in the embodiments, clamps are used to open or close tubes. However, other features such as valves can be utilized instead.

The extracorporeal circuit disclosed here makes it possible to relatively quickly collect a priming solution when the priming solution is displaced by blood after the priming solution is fed to the extracorporeal circuit in order to prime the extracorporeal circuit. After the extracorporeal circuit is primed, when a priming solution is displaced by blood, that is retrograde autologous priming (RAP) is performed, the priming solution can be readily and quickly collected by performing simple manipulations on the extracorporeal circuit. Consequently, when the extracorporeal circuit is used to perform extracorporeal circulation, a procedure can quickly proceed to the next step (extracorporeal circulation step). Also, in the extracorporeal circuit, since the priming solution is collected, hemodilution caused by the priming solution can be inhibited or prevented.