Hemodialysis apparatus operating method and hemodialysis apparatus

A hemodialysis apparatus 1 is provided with a dialyzer 2 for performing hemodialysis, a blood circuit 3 connected to the dialyzer, a dialysis solution circuit 4 connected to the dialyzer, a replacement fluid port 31 provided in the dialysis solution circuit and capable of being opened and closed by a lid member, and a replacement fluid passage 6 having its one end connected to the blood circuit and the other end connected to the replacement fluid port.

TECHNICAL FIELD

The present invention relates to a hemodialysis apparatus operating method and a hemodialysis apparatus and, more particularly, to a hemodialysis apparatus operating method and a hemodialysis apparatus in which a replacement fluid passage is connected to a dialysis solution circuit when a dialytic treatment is performed.

BACKGROUND ART

Conventionally, hemodialysis is performed with a hemodialysis apparatus causing blood and a dialysis solution to flow through a dialyzer. A blood circuit through which blood is caused to flow and a dialysis solution circuit through which the dialysis solution is caused to flow are connected to the dialyzer.

As such a hemodialysis apparatus, one capable of performing an online hemodialysis filtration treatment (hereinafter referred to as on-line HDF (hemodiafiltration)) by supplying a dialysis solution to a blood circuit during dialytic treatment (Patent Literature 1) is known.

In the hemodialysis apparatus performing the on-line HDF, a replacement fluid passage is provided between the blood circuit and the dialysis solution circuit, and a replacement fluid port for connection to the replacement fluid passage is provided for the dialysis solution circuit. This replacement fluid port can be opened and closed by a lid member.

When preparatory operations for hemodialysis treatment are performed, the replacement fluid port is in the closed state, with the replacement fluid passage detached from the replacement fluid port. In this state, a dialysis solution substitution step to fill the dialysis solution circuit with the dialysis solution is performed. The lid member is thereafter removed from the replacement fluid port and the replacement fluid passage is connected to the replacement fluid port.

PRIOR ART DOCUMENT

Patent Literature

SUMMARY OF INVENTION

Problem to be Solved by the Invention

In the hemodialysis apparatus having the construction disclosed in Patent Literature 1, the pressure in the dialysis solution circuit is increased as a result of execution of the above-described dialysis solution substitution step, and the dialysis solution overflows to the outside when the lid member is removed from the replacement fluid port, resulting in an unsanitary condition.

In view of this problem, an object of the present invention is to provide a hemodialysis apparatus operating method and a hemodialysis apparatus capable of performing operations in a sanitary manner by preventing overflowing of a dialysis solution.

Means for Solving the Problem

A method of operating a hemodialysis apparatus according to the present invention is a method of operating a hemodialysis apparatus provided with a dialyzer for performing hemodialysis, a blood circuit connected to the dialyzer, a dialysis solution circuit connected to the dialyzer, a replacement fluid port provided in the dialysis solution circuit and capable of being opened and closed by a lid member, and a replacement fluid passage having its one end connected to the blood circuit and the other end connected to the replacement fluid port,

in which after a dialysis fluid substitution step of filling the dialysis solution circuit with a dialysis solution, the lid member is detached from the replacement fluid port to change the replacement fluid port from a closed state to an open state, and the replacement fluid passage is connected to the replacement fluid port in the open state, the method including:

performing, after the dialysis fluid substitution step, a negative pressure forming step to make the pressure in the dialysis solution circuit negative so that the dialysis solution does not overflow when the replacement fluid port is opened, and thereafter changing the replacement fluid port from the closed state to the open state.

A hemodialysis apparatus according to the present invention is a hemodialysis apparatus including a dialyzer for performing hemodialysis, a blood circuit connected to the dialyzer, a dialysis solution circuit connected to the dialyzer, dialysis solution flowing means for flowing the dialysis solution in the dialysis solution circuit, control means for controlling the dialysis solution flowing means, a replacement fluid port provided in the dialysis solution circuit and capable of being opened and closed by a lid member, and a replacement fluid passage having its one end connected to the blood circuit and the other end connected to the replacement fluid port in an open state,

wherein the dialysis solution flowing means has a construction capable of forming a negative pressure in the dialysis solution circuit under the control of the control means, and

wherein the control means makes the pressure in the dialysis solution circuit negative by controlling the dialysis solution flowing means from a state where the replacement fluid port is in a closed state and the dialysis solution circuit is filled with the dialysis solution, thereby enabling prevention of overflowing of the dialysis solution even when the replacement fluid port is opened, and stands by until the replacement fluid port is opened.

Advantageous Effects of Invention

According to the present invention, the pressure in the dialysis solution circuit in which the replacement fluid port is provided is made negative by the negative pressure forming step. Therefore, even in a state where the replacement fluid port is opened when the replacement fluid passage is connected to the replacement fluid port, the dialysis solution in the dialysis solution circuit is drawn into the circuit.

Prevention of overflowing of the dialysis solution from the replacement fluid port can thus be achieved to enable the performing of operations in a sanitary manner.

According to the present invention, the pressure in the dialysis solution circuit is made negative under the control of the control means, thereby enabling prevention of overflowing of the dialysis solution even when the replacement fluid port is opened. Also, this condition is maintained until the replacement fluid port is thereafter opened. Prevention of overflowing of the dialysis solution from the replacement fluid port is thus achieved to enable performing operations in a sanitary manner.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below.FIGS. 1 and 2show a hemodialysis apparatus1for performing hemodialysis.FIG. 1is a circuit diagram andFIG. 2is a front view.

The hemodialysis apparatus1in the present embodiment is provided with a dialyzer2with which hemodialysis is performed, a blood circuit3connected to the dialyzer2, and a dialysis solution circuit4(not illustrated inFIG. 2) connected to the dialyzer2. The hemodialysis apparatus1is controlled by control means not illustrated and various operations can be performed on the hemodialysis apparatus1by means of a touch-panel-type monitor5illustrated inFIG. 2.

The hemodialysis apparatus1in the present embodiment is capable of performing on-line HDF by supplying a fresh dialysis solution to a patient through the blood circuit3and is provided with a replacement fluid passage6branching off from the blood circuit3and capable of being connected to the dialysis solution circuit4.

The construction of the hemodialysis apparatus1described in the description of the present embodiment is known per se and a method of operating the hemodialysis apparatus1according to the present invention can be carried out with such a known hemodialysis apparatus1.

The dialyzer2is vertically held on a side surface of a main body7, as shown inFIG. 2. The interior of the dialyzer2is partitioned into a blood chamber and a dialysis solution chamber by a hollow fiber membrane not illustrated. Blood flows in the blood chamber in a top-to-bottom direction as viewed in the figure, while the dialysis solution flows in the dialysis solution chamber in a bottom-to-top direction as viewed in the figure.

The blood circuit3is provided with an artery-side passage11connected to an artery of a patient and to an upper end of the dialyzer2, and a vein-side passage12connected to a vein and to a lower end of the dialyzer2. The replacement fluid passage6is connected so as to branch off from the artery-side passage11.

On the artery-side passage11, a puncturing needle11ato be inserted in a patient, clamp means13for opening/closing the artery-side passage11, a pressure gage14for measuring pressure (not illustrated inFIG. 2), a syringe15containing a blood coagulation preventive agent and a blood pump16constituted by a tube pump (peristaltic pump) for feeding blood are provided.

The syringe15is attached to the main body7, and pressing means7afor pressing a plunger15aof the syringe15is provided on the main body7. The blood coagulation agent is supplied into the artery-side passage11by the pressing means7apressing the plunger15a.

A drip chamber17for removing air from blood and a puncturing needle12ato be inserted in a patient are provided on the vein-side passage12. A pressure gage18for measuring pressure (not illustrated inFIG. 2) is provided on the drip chamber17.

Referring toFIG. 2, the pressure gage14on the artery-side passage11and the pressure gage18on the vein-side passage12are provided inside the main body7, and tubes from the artery-side passage11and the vein-side passage12are respectively connected to pressure ports7band7crespectively communicating with the pressure gages14and18.

The replacement fluid passage6is connected to the artery-side passage11at a position between the blood pump16and the dialyzer2. The replacement fluid passage6is replaced together with the dialyzer2and blood circuit3each time dialysis treatment is performed.

A coupler6a(seeFIG. 5) for connection to a below-described replacement fluid port31provided on the main body7is provided on an end portion of the replacement fluid passage6. A replacement fluid pump19constituted by a tube pump like the blood pump16is provided on the replacement fluid passage6.

The replacement fluid passage6may alternatively be connected to the vein-side passage12according to a judgment made by a doctor in charge.

The dialysis solution circuit4is provided with first and second dialysis solution chambers21and22, each of which the dialysis solution is supplied to or discharged from and are identical in shape to each other, a solution feed passage23through which the fresh dialysis solution is fed to the first or second dialysis solution chamber21or22, a dialysis solution supply passage24through which the fresh dialysis solution is supplied from the first or second dialysis solution chamber21or22to the dialyzer2, a dialysis solution recovery passage25through which the used dialysis solution having passed through the dialyzer2is recovered into the first or second dialysis solution chamber21or22, and a drain passage26through which the used dialysis solution is discharged from the first or second dialysis solution chamber21or22to a drain tank not illustrated. These components are housed in the main body7.

In the present embodiment, pumps and opening/closing valves constituting the dialysis solution circuit4constitute dialysis solution flowing means for causing the dialysis solution to flow through the dialysis solution circuit4and are controlled by the above-mentioned control means.

Each of the interiors of the first and second dialysis solution chambers21and22is partitioned by one diaphragm, thereby forming supply sections21aand22awhich contain the fresh dialysis solution and the recovery sections21band22bwhich contain the used dialysis solution.

A solution feed pump which feeds the fresh dialysis solution, and which is not illustrated, is provided on the solution feed passage23. A downstream portion of the solution feed passage23diverges into divergent portions extending in two directions to connect respectively to the supply sections21aand22bof the first and second dialysis solution chambers21and22. Solution feed valves V1and V2are respectively provided in the divergent portions.

An upstream portion of the dialysis solution supply passage24diverges into divergent portions extending in two directions to connect respectively to the supply sections21aand22bof he first and second dialysis solution chambers21and22. A coupler24a(seeFIG. 5) to be connected to the dialyzer2is provided on a downstream end of the dialysis solution supply passage24. Supply valves V3and V4are respectively provided in the divergent portions.

A coupler25a(seeFIG. 5) to be connected to the dialyzer is provided on an upstream end of the dialysis solution recovery passage25. A downstream portion of the dialysis solution recovery passage25diverges into divergent portions extending in two directions to connect respectively to the recovery sections21band22bof the first and second dialysis solution chambers21and22.

A dialysis solution pump27for feeding the dialysis solution is provided on the dialysis solution recovery passage25upstream of the divergent portions, and recovery valves V5and V6are provided in the divergent portions.

An upstream portion of the drain passage26diverges into divergent portions extending in two directions to connect respectively to the recovery sections21band22bof the first and second dialysis solution chambers21and22. A downstream portion of the drain passage26is connected to the drawn tank not illustrated. Drain valves V7and V8are respectively provided in the divergent portions.

Flowing of the dialysis solution in the above-described dialysis solution circuit4will be described. The solution feed pump on the solution feed passage23and the dialysis solution pump27on the dialysis solution recovery passage25are operated. In this state, with respect to the first dialysis solution chamber21, the solution feed valve VI and the drain valve V7are opened and the supply valve V3and the recovery valve V5are closed.

The fresh dialysis solution then flows from the solution feed passage23into the supply section21aof the first dialysis solution chamber21to deform the diaphragm and reduce the capacity of the recovery section21b. The used dialysis solution contained in the recovery section21bis thereby discharged to the outside through the drain passage26.

On the other hand, with respect to the second dialysis solution chamber22, the supply valve V4and the recovery valve V6are opened and the solution feed valve V2and the drain valve V8are closed. The used dialysis solution then flows into the recovery section22bto deform the diaphragm and reduce the capacity of the supply section22a. The fresh dialysis solution contained in the supply section22ais thereby flowed through the dialysis solution supply passage24to be supplied to the dialyzer2.

Thereafter, the solution feed valves V1and V2, the supply valves V3and V4, the recovery valves V5and V6and the drain valves V7and V8are alternately opened and closed to supply the fresh dialysis solution from the first or second dialysis solution chamber21or22to the dialyzer2through the dialysis solution supply passage24to retrieve the used dialysis solution having passed through the dialyzer2to the first or second dialysis solution chamber21or22through the dialysis solution recovery passage25, thereby maintaining the flowing of the dialysis solution.

A concentration measurement device28for measuring the concentration of the dialysis solution is provided on the dialysis solution supply passage24downstream of the divergent portions. A first dialysis solution filter F1for removing detrimental ingredients in the dialysis solution and first and second opening/closing valves V11and V12are also provided in the dialysis solution supply passage24. The first and second opening/closing valves V11and V12are provided by being spaced apart by a predetermined distance from each other.

The first dialysis solution filter F1is partitioned into an upstream section and a downstream section by a semipermeable membrane. When the dialysis solution permeates through the semipermeable membrane from the upstream section into the downstream section, the semipermeable membrane removes detrimental ingredients.

A first bypass passage29for communication between the dialysis solution supply passage24and the dialysis solution recovery passage25is connected to the upstream section of the first dialysis solution filter F1. A third opening/closing valve V13is provided in the first bypass passage29.

A second bypass passage30for communication between the dialysis solution supply passage24and the dialysis solution recovery passage25is connected to a point between the first and second opening/closing valves V11and V12. In the second bypass passage30are provided in order from the upstream side a second dialysis solution filter F2, the replacement fluid port31connected to the replacement fluid passage6and a fourth opening/closing valve V14.

The second dialysis solution filter F2is also partitioned into an upstream section and a downstream section by a semipermeable membrane, as is the first dialysis solution filter F1. A third bypass passage32for communication between the dialysis solution supply passage24and the dialysis solution recovery passage25through the second bypass passage30is connected to the upstream section. A fifth opening/closing valve V15is provided in the third bypass passage32.

At the time of dialysis treatment, the replacement fluid passage6is connected to the replacement fluid port31, which is described below in detail, and the dialysis solution is supplied into the replacement fluid passage6. When preparations for dialysis treatment are made, the replacement fluid passage6is not connected; the dialysis solution is flowed through the second bypass passage30without being supplied into the replacement fluid passage6.

In the dialysis solution recovery passage25there are provided in order from the dialyzer2side a sixth opening/closing valve V16, a pressure sensor33for measuring pressure, the dialysis solution pump27for feeding the dialysis solution and a deaeration tank34for removing air in the dialysis solution.

A downstream end portion of the first bypass passage29is connected at a position adjacent to the upstream side of the pressure sensor33; a downstream end portion of the second bypass passage30is connected at a position adjacent to the downstream side of the sixth opening/closing valve V16; and a downstream end portion of the third bypass passage32is connected between the first bypass passage29and the second bypass passage30.

On the deaeration tank34described below in detail, a fourth bypass passage35for communication between the dialysis solution recovery passage25and the drain passage26is provided. A seventh opening/closing valve17is provided on the fourth bypass passage35.

A fifth bypass passage36for communication between the dialysis solution recovery passage25and the drain passage26is further provided downstream of the deaeration tank34. A water removal pump37for removing water when dialysis treatment is performed is provided on the fifth bypass passage36.

The replacement fluid port31provided in the second bypass passage30will be described with reference toFIG. 3. Referring toFIG. 3, the replacement fluid port31is in a state of being closed with a lid member44described below, with the replacement fluid passage6not connected thereto.

The replacement fluid port31has a base member41fixed on the main body7, an outer port42in the form of a cylinder closed at its bottom, fixed to the base member41, an inner port43provided in the outer port42, the lid member44which closes the inner port43as well as the outer port42, a lever45for moving the lid member44, and opening/closing detection means46for detecting an open/closed state of the lid member44.

The base member41is a member in the form of a disk such as illustrated inFIG. 2. The lever45is provided so as to be rotatable on a through hole formed approximately at a center of the base member41.

The outer port42is provided so that its bottom surface faces in a lateral direction and is fixed so as to open at an end surface of the base member41. A ring seal47in which the lid member44is fitted is provided in a distal end portion of an inner circumferential surface of the outer port42.

A flow inlet42ato which upstream piping30aconstituting the second bypass passage30is connected is formed outside the bottom surface of the outer port42. A discharge outlet42bto which downstream piping30bconstituting the second bypass passage30is connected is formed below an outer circumferential surface of the outer port42.

The inner port43is a tubular member provided coaxially with the outer port42. A base portion of the inner port43is fixed on a bottom surface of the outer port42and communicates with the flow inlet42a.

A distal end of the inner port43projects out of the main body7from the outer port42. A helical groove for connection of the coupler6aof the replacement fluid passage6is formed in an outer circumferential surface of the inner port43.

The lid member44has the shape of a cylinder closed at its bottom. In a closing state illustrated inFIG. 3, an outer circumferential surface of the lid member44is maintained in close contact with the ring seal47provided in the inner circumferential surface of the outer port42, thereby forming a space in the outer port42and the lid member44.

In this closing state, a gap is formed between the inner port43and the lid member44, thereby enabling the dialysis solution discharged from the inner port43to flow through the space formed by the lid member44and the outer port42to be discharged out of the discharge outlet42b.

That is, in the replacement fluid port31in the state of being closed with the lid member44, the dialysis solution having flowed into the upstream piping30aof the second bypass passage30passes through the space formed by the lid member44and the outer port42and is discharged through the downstream piping30band fed into the dialysis solution recovery passage25.

Conversely, when the replacement fluid passage6is connected to the inner port43in the open state after removing the lid member44from the outer port42, the opening portion of the outer port42is exposed to the outside and the dialysis solution flows from the inner port43into the replacement fluid passage6and flows into the artery-side passage11of the blood circuit3.

The lever45is pivotally supported by a rod45aprovided approximately at a center so as to be rotatable relative to the base member41. The lid member44is fixed on the lever45at one end of the same, and a pin48is provided on an end portion of the lever45at the opposite side.

The rod45apasses through the base member41. A spring49is resiliently interposed between a portion of the rod45aprojecting inwardly in the main body7and the base member41. The lever45is constantly urged in a direction toward the main body7by the spring49.

Stopper holes41aeach closed at its bottom and adapted to receive the pin48and regulate the lever45from rotating are formed in two places in the base member41. The pin48is received in one of the stopper holes41awhen the lever45is positioned in the closing state shown inFIG. 3.

The other stopper hole not illustrated is formed at a position at which the lever45is held at such an angle as not to hinder attachment of the replacement fluid passage6.

The opening/closing detection means46is constituted by a magnet provided on the distal end of the pin48, which magnet is not illustrated, and a magnetism sensor50attached to the base member41on the reverse side opposite from the stopper hole41a.

In the closing state illustrated inFIG. 3, the pin48is inserted in the stopper hole41a, the magnet is close to the magnetism sensor50, and the state in which the replacement fluid port31is closed is recognized by detecting the magnetic force of the magnet with the magnetism sensor50.

When the lever45is turned from the state shown inFIG. 3, the pin48is detached from the stopper hole41aand the magnetic force of the magnet cannot be detected with the magnetism sensor50. As a result, the state in which the replacement fluid port31is open is recognized.

The deaeration tank34provided in the dialysis solution recovery passage25will be described with reference toFIG. 4. the deaeration tank34has a case51containing the dialysis solution, a cap52tightly closing the case51and a float53which moves upward or downward by following the liquid level of the dialysis solution in the case51.

Upstream piping25aof the dialysis solution recovery passage25is connected to a bottom surface of the case51, and downstream piping25bof the dialysis solution recovery passage25is connected to a side surface higher to some extent than the bottom surface. The fourth bypass passage35is also connected at a position higher to some extent than the position of connection of the downstream piping25b.

A rod53apassing through the cap52and slidable on the cap52is provided on the float53. When the liquid level of the dialysis solution in the case51is changed, the float53moves upward or downward by following the liquid level.

A contactless switch (not illustrated) is provided on the cap52. When the liquid level of the dialysis solution in the case51is moved downward and when the float53is moved apart from the cap52by a distance equal to or larger than a predetermined distance, it is recognized by means of the switch that a volume of air equal to or larger than a predetermined volume is contained in the case51.

When a volume of air equal to or larger than the predetermined volume is contained in the case51in dialysis treatment, the contactless switch is operated to open the seventh opening/closing valve V17in the fourth bypass passage35, thereby causing the air in the case51to be discharged into the drain passage26through the fourth bypass passage35.

The deaeration tank34is capable of flowing the dialysis solution through the fourth bypass passage35by forcibly flowing the dialysis solution into the case51when the seventh opening/closing valve17is open, as described below.

The method of operating the hemodialysis apparatus1having the above-described construction will be described. A procedure for preparations for dialysis treatment with the above-described hemodialysis apparatus1will be described with reference toFIGS. 5 to 8. In each ofFIGS. 5 to 8, the color of a circuit attached to each opening/closing valve indicates the open/closed state, the white circle indicating the open state, the black circle indicating the closed state.

The following is assumed unless otherwise noted: the solution feed pump and the dialysis solution pump27are operating; the solution feed valves V1and V2, the supply valves V3and V4, the recovery valves V5and V6and the drain valves V7and V8are alternately opened and closed by the control means; and the dialysis solution is being flowed through the dialysis solution flowing means.

FIG. 5is a diagram for explaining a dialysis solution substitution step of replacing a cleaning liquid filling the dialysis solution circuit4with the dialysis solution.

After the completion of preceding dialysis treatment, the dialyzer2and the blood circuit3are detached from the hemodialysis apparatus1, and the dialysis solution supply passage24and the dialysis solution recovery passage25are directly connected to each other by the couplers24aand25a.

Since the replacement fluid passage6branches off from the blood circuit3, the replacement fluid passage6is detached from the replacement fluid port31, and the replacement fluid port31is closed with the lid member44.

In this state, the interior of the dialysis solution circuit4is cleaned with the cleaning liquid. The interior of the dialysis solution circuit4is filled with the cleaning liquid before dialysis treatment is newly performed. This dialysis solution substitution step is a step of replacing the cleaning liquid filling the dialysis solution circuit4with the dialysis solution.

This step will be concretely described. The dialysis solution supplied from the first or second dialysis solution chamber21or22flows through the dialysis solution supply passage24, passes through the couplers24aand25a, and thereafter flows through the dialysis solution recovery passage25. The cleaning liquid contained in these passages is replaced with the fresh dialysis solution.

Simultaneously, the third to fifth and seventh opening/closing valves V13to V15and V17and the water removal pump37are operated as desired to also replace the cleaning liquid contained in the first to fifth bypass passages29,30,32,35, and36with the dialysis solution.

At this time, the replacement fluid port31of the second bypass passage30is in the closed state and the outer port42is closed with the lid member44. Therefore, the dialysis solution discharged from the inner port43fills the space formed by the outer port42and the lid member44.

Therefore, if the lid member44is opened when the dialysis solution substitution step is completed, the dialysis solution filling the space formed by the outer port42and the lid member44overflows to the outside.

In the deaeration tank34provided in the dialysis solution recovery passage25, the interior of the case51is also filled with the dialysis solution when the fourth bypass passage35is filled with the dialysis solution.

FIG. 6is a negative pressure forming step of making the pressure in the dialysis solution circuit4negative.

Overflowing of the dialysis solution to the outside when the replacement fluid port31is opened from the closed state can be prevented by performing this negative pressure forming step and a negative pressure maintenance step described below.

The step will be specifically described. In a state where the dialysis solution is supplied from the first or second dialysis solution chamber21or22, the second opening/closing valve V12in the dialysis solution supply passage24, the sixth opening/closing valve V16in the dialysis solution recovery passage25and the third opening/closing valve V13in the first bypass passage29are closed.

On the other hand, the fourth opening/closing valve V14in the second bypass passage30and the fifth opening/closing valve V15in the third bypass passage32are opened to cause the dialysis solution to flow through the second bypass passage30and the third bypass passage32. Further, the seventh opening/closing valve V17in the fourth bypass passage35is opened.

At this time, since the deaeration tank34to which the fourth bypass passage35is connected is filled with the dialysis solution, the dialysis solution flows from the deaeration tank34into the fourth bypass passage35and is thereafter discharged into the drain passage26.

In this way, part of the dialysis solution flowing through the dialysis solution circuit4is forcibly discharged from the dialysis solution recovery passage25into the fourth bypass passage35. The pressure in the entire dialysis solution circuit4is thereby made negative. The pressure in the second bypass passage30in particular is thereby made negative so that the pressure in the space formed by the outer port42and the lid member44is negative.

When this negative pressure forming step is started, the negative pressure in the dialysis solution passage25is measured with the pressure sensor33provided on the dialysis solution recovery passage25. When a negative pressure is reached such that the dialysis solution does not overflow when the replacement fluid port31is opened, transition to the subsequent negative pressure maintenance step is made.

If the negative pressure is reduced below the pressure for preventing the dialysis solution from overflowing when the replacement fluid port31is opened, there is a risk of external unclean air intruding into the circuit.

The degree of negative pressure described above may be set by experimentally determining a suitable value with reference to factors including the outside diameters of the outer port42and the inner port43.

FIG. 7is a diagram for explaining the negative pressure maintenance step of maintaining the negative pressure in the dialysis solution circuit4.

In this negative pressure maintenance step, the negative pressure condition in the replacement fluid port31provided in the second bypass passage30having the internal pressure made negative by the above-described negative pressure forming step is maintained until the replacement fluid passage5is connected.

More specifically, in contrast with the negative pressure forming step described with reference toFIG. 6, the first, fourth, fifth and seventh valves V11, V14, V15, and V17are closed and only the third opening/closing valve V13in the first bypass passage29is opened.

As a result, the dialysis solution flows from the dialysis solution supply passage24into the dialysis solution recovery passage25through the first bypass passage29. On the other hand, a negative pressure state in which flowing of the dialysis solution is prevented is maintained in the second bypass passage30since the adjacent first and second opening/closing valves V11and V12and fourth and fifth valves V14and V15are closed.

As a result, also in the replacement fluid port31provided in the second bypass passage30, the negative pressure in the space formed by the outer port42and the lid member44is maintained.

After the completion of this negative pressure maintenance step, the control means notifies the monitor5of the state where the replacement fluid passage6can be connected to the replacement fluid port31.

FIG. 8is a diagram for explaining a replacement fluid passage dialysis solution supply step (priming) of connecting the replacement fluid passage6to the replacement fluid port31and filling the replacement fluid passage6with the dialysis solution.

An operator first attaches the new dialyzer2and the blood circuit3to the main body7and connects the dialysis solution supply passage24and the dialysis solution recovery passage25in the dialysis solution circuit4to the dialyzer2by using the couplers24aand25a.

Subsequently, the operator changes the lid member44from the closed state to the open state by operating the lever45of the replacement fluid port31and connects the end of the replacement fluid passage6to the replacement fluid port31.

Since at this time the pressure in the second bypass passage30is maintained at a negative value by the negative pressure maintenance step shown inFIG. 7, parts of the dialysis solution in the outer port42and the inner port43are respectively sucked to the upstream piping30aand downstream piping30bof the second bypass passage30even when the lid member44is detached from the outer port42. Therefore, the dialysis solution does not overflow out of the replacement fluid port31.

After the replacement fluid passage5is connected in this way, the first opening/closing valve V11in the dialysis solution supply passage24is opened and the replacement fluid pump19is operated in this state, thereby supplying the dialysis solution from the replacement fluid port31provided in the second bypass passage30into the replacement fluid passage6so that the replacement fluid passage6is filled with the dialysis solution.

On the other hand, a blood transfusion bag54containing physiological saline is connected to the artery-side passage11in the blood circuit3and the blood pump16is operated, thereby filling the blood circuit3with physiological saline from the blood transfusion bag54. The preparations for dialysis treatment are thus completed.

In the above-described embodiment, a negative pressure forming step to make the pressure in the dialysis solution circuit4negative is provided after the dialysis solution substitution step to fill the dialysis solution circuit4with the dialysis solution, thereby enabling the prevention of the overflowing of the dialysis solution in the replacement fluid port31when the replacement fluid port31, closed with the lid member44, is opened.

That is, in the dialysis solution substitution step, the dialysis solution circuit4has a positive low internal pressure as a result of the feeding of the dialysis solution from the first and second dialysis solution chambers21and22. There is, therefore, a problem that if the replacement fluid port is opened immediately after the dialysis solution substitution step, the dialysis solution is ejected and attached to the main body7, the floor, etc., and an unsanitary condition results.

In the above-described embodiment, the second bypass passage30for communication between the dialysis solution supply passage24and the dialysis solution recovery passage25is provided and the dialysis solution flows through the second bypass passage30when the replacement fluid port31is closed.

Even in this arrangement, the pressure in the replacement fluid port31can also be made negative by making the pressure in the second bypass passage30negative by the above-described negative pressure forming step, thus preventing the dialysis solution from overflowing from the replacement fluid port31when the replacement fluid port31is opened.

Further, when the negative pressure forming step is performed, the dialysis solution can be discharged through the deaeration tank34and the fourth bypass passage35used at the time of ordinary dialysis treatment, thus enabling making the pressure in the dialysis solution circuit4negative when the well-known hemodialysis apparatus1is used.

When the negative pressure forming step is performed, the pressure is measured with the pressure sensor33provided on the dialysis solution recovery passage25. Transition to the negative pressure maintenance step is made after a detection result indicating that the pressure in the dialysis solution circuit4has reached a predetermined negative pressure is recognized, thus achieving prevention of an excessive negative pressure in the dialysis solution circuit4.

The pressure is measured with the pressure sensor33and, when a detection result indicating that the pressure in the dialysis solution circuit4has reached a predetermined negative pressure is recognized, the monitor5is notified of the state where the replacement fluid passage6can be connected to the replacement fluid port31, thus enabling an operator to attach the replacement fluid passage6by suitable timing.

Further, when a detection result indicating that the replacement fluid port31has been opened is recognized with the magnetism sensor50, a message to urge the operator to start the replacement fluid passage dialysis solution supply step (priming) can be displayed on the monitor5by the control means.

FIG. 9is a circuit diagram of a hemodialysis apparatus1according to a second embodiment. The same portions as those of the hemodialysis apparatus1according to the first embodiment will not be described in the following description.

The hemodialysis apparatus1according to the present embodiment has intermediate sections21cand22ccontaining silicone oil between the supply sections21aand22band the recovery sections21band22bin the first and second dialysis solution chambers21and22constituting the dialysis solution circuit4, while the fifth bypass passage36and the water removal pump37in the first embodiment are not provided. The intermediate sections21cand22care connected to each other by a silicone oil pump61.

In the hemodialysis apparatus1having such first and second dialysis solution chambers21and22, the capacity of one of the intermediate sections21cand22cis reduced by the silicone oil pump61provided as the dialysis solution flowing means to produce a negative pressure in the recovery section21bor22badjacent to the intermediate section, thus enabling removal of water during dialysis treatment.

The hemodialysis apparatus1having such a construction is also capable of preventing the dialysis solution from overflowing out of the replacement fluid port31provided in the second bypass passage30when the replacement fluid passage6is connected to the replacement fluid port31, as is the hemodialysis apparatus1in the first embodiment.

More specifically, in the negative pressure forming step to make the pressure in the dialysis solution circuit4negative in the first embodiment, the seventh opening/closing valve V17is opened to cause the dialysis solution to flow through the fourth bypass passage35. In the present embodiment, however, there is no need to open the seventh opening/closing valve V17.

Instead, the silicone oil pump61is operated to reduce the capacity of one of the dialysis solution chambers, thereby producing a negative pressure in the dialysis solution circuit4. The pressure in the replacement fluid port31can be made negative in this way.

In the negative pressure forming step shown inFIG. 6, in the above-described embodiment, the dialysis solution is caused to flow through the fourth bypass passage35connected to the deaeration tank34provided in the dialysis solution recovery passage25to make the pressure in the dialysis solution circuit4negative. However, another bypass circuit and an opening/closing valve for opening/closing the bypass circuit may be provided between the dialysis solution recovery passage25and the drain passage26.

In the hemodialysis apparatus1removing water by using the water removal pump37as in the first embodiment, the water removal pump37may be operated in the negative pressure forming step to make the pressure in the dialysis solution circuit4negative.

REFERENCE SIGNS LIST