JP2002204827A - Venous blood storage tub with cardiotomy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a venous blood storing tub with a cardiotomy which properly removes bubbles having flown into the blood storing tub without flowing out to the downstream of the blood storing tub and easily controls the surface of stored blood. SOLUTION: The tub is provided with a housing 2 having a venous blood flow-in port 4, an intracardiac blood flow-in port 5 and a blood flow-out port, a venous blood filtering net 8 existing extending from the bottom part of the housing to an upper part within the housing so as to be communicated with the venous blood flow-in port and the intracardiac blood flow-in port, a venous blood introduction tube 7 which is connected to the venous blood flow-in port and the tip of which is extended to the neighborhood of the bottom part within the venous blood filtering net, a defoaming member 11 installed above the venous blood filtering net to hold defoaming agent, and an intracardiac blood filtering and defoaming part 10 installed above the defoaming member to be communicated with the intracardiac blood flow-in port. A distance between the tip of the venous blood introduction tube and the venous blood filtering net is >=7 mm and the opening size of the venous blood filtering net is 20 to 55 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood reservoir installed in an extracorporeal circulation circuit for removing air bubbles and the like in blood, and in particular, air bubbles flowing into the blood reservoir are not discharged downstream of the blood reservoir. The present invention relates to a cardiotomy-equipped venous blood reservoir suitably removed.

[0002]

2. Description of the Related Art During cardiac surgery, extracorporeal circulation using an artificial lung extracorporeal blood circuit is performed as an alternative to the function of the heart and lungs. The blood circuit includes an artificial lung for adding oxygen to venous blood removed from a patient's vein and a blood reservoir for temporarily storing blood removed from the vein (called a venous blood reservoir). Also, a blood reservoir (called an intracardiac blood reservoir) is provided for aspirating and collecting blood overflowing into the heart cavity (operating field), filtering foreign substances, and temporarily storing the collected foreign substances. Intracardiac blood is better than venous blood,
In order to contain a large amount of foreign substances such as clots and air bubbles, the intracardiac blood storage tank has an intracardiac blood filtration and defoaming section comprising a defoaming layer for defoaming blood and a filtration layer for removing foreign substances. (Cardiotomy section). In recent years, a blood reservoir has been devised in which the cardiotomy section and the venous blood reservoir are integrated,
One example of the structure is disclosed in Japanese Patent Application Laid-Open No. 5-317420.

[0003] Such a blood reservoir has a buffer function for adjusting the amount of blood in the circuit and keeping the amount of blood returned constant. In addition, a filter (filtration net) for removing foreign substances and bubbles in blood supplied to the blood reservoir is provided. The venous blood is introduced into the blood storage chamber through a venous blood inlet tube having one end connected to the venous blood inlet and the other end extending to near the bottom of the blood reservoir. The venous blood introduction tube is surrounded by a filtration network around the venous blood introduction tube, and minute foreign substances and bubbles are removed from the venous blood by the filtration network. On the other hand, the intracardiac blood is introduced from the intracardiac blood inlet, and after the foreign substances such as meat pieces, fat, and clot are removed in the cardiotomy section and the air bubbles, the venous blood merges with the venous blood in the blood reservoir. An antifoaming device is provided above the blood reservoir to provide a function of defoaming air bubbles collected on the surface of the blood stored in the blood reservoir. As a defoaming device, generally,
A configuration in which a silicone antifoaming agent is supported on an antifoaming member is known.

[0004]

However, existing venous blood reservoirs with cardiotomy have the following problems.

First, since the cross-sectional area inside the filter at the position where the tip of the venous blood introducing tube is located is relatively small,
Turbulence is likely to occur at the place where venous blood supplied from the venous blood introduction tube flows into the blood storage chamber, and therefore, foaming tends to increase.

In addition, when blood flows out of the venous blood introduction tube, the filter surface is present at a position close to the outflow point, so that air bubbles flowing in together with the blood or air bubbles generated by turbulence flow into the blood storage chamber. Before it rises to the liquid level, it easily flows out through the filter.

On the other hand, it is conceivable to prevent the outflow of air bubbles by reducing the pore size of the filter. However, if the pore size is too small, the resistance to the passage of blood through the venous blood filtration network increases. The amount of extra blood stored in the filtration network (hereinafter referred to as "dynamic filling volume")
And it becomes difficult to control the blood storage surface.

Accordingly, it is an object of the present invention to provide a blood reservoir in which bubbles flowing into the blood reservoir are appropriately removed without flowing out to the downstream of the blood reservoir, and the surface of the blood reservoir is easily controlled.

[0009]

To solve the above-mentioned problems, a cardiotomy-equipped venous blood reservoir of the present invention comprises a housing having a venous blood inlet, an intracardiac blood inlet and a blood outlet, and a housing having a blood outlet. A venous blood filtration network, which extends from the bottom to the top and is installed so as to communicate with the venous blood inlet and the intracardiac blood inlet; A venous blood introduction tube extending to the vicinity of the bottom, an antifoaming member installed above the venous blood filtration network and carrying an antifoaming agent, and an intracardiac installed above the antifoaming member and communicating with the intracardiac blood inlet. A blood filtration and defoaming unit. The venous blood filtration network has a structure that wraps around the venous blood introduction tube, and the venous blood introduction tube extends to near the bottom of the venous blood filtration network.
The distance between the tip of the venous blood introduction tube and the venous blood filtration network is 7 mm or more, and the opening size of the venous blood filtration network is 20 mm.
５５55 μm.

According to this configuration, the turbulence of the blood flow in the blood reservoir is small, the flow velocity is slow, and the residence time of the blood is long, so that the outflow of air bubbles downstream of the blood reservoir is sufficiently reduced. Is done. Therefore, the air bubbles that have flowed into the blood storage tank are appropriately removed without flowing out downstream of the blood storage tank, and the control of the blood storage surface is easy.

[0011]

FIG. 1 is a front view showing a blood reservoir according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a side structure at a position indicated by AA in FIG.

As shown in FIGS. 1 and 2, the blood reservoir 1 has a housing 2 and a blood reservoir 3 for storing blood therein. In the upper part of the housing 2, a tubular venous blood inlet 4 and an intracardiac blood inlet 5 which are in communication with the blood storage chamber 3 are formed. The venous blood inlet 4 is connected to a tube of a blood removal line of a blood circuit for extracorporeal circulation. The intracardiac blood inlet 5 is connected to a tube of an intracardiac blood suction line.
A tubular blood outlet 6 communicating with the blood storage chamber 3 is formed in a lower portion of the housing 2. The blood outlet 6 is connected to a tube of a blood supply line of a blood circuit for extracorporeal circulation.

Reference numeral 7 denotes a venous blood introduction tube connected to the venous blood inlet 4, and a venous blood filtration network 8 is arranged around the tube. The venous blood filtration network 8 has a structure that wraps around the venous blood introduction tube 7. The venous blood introduction tube 7 extends to near the bottom of the venous blood filtration network 8, and its tip is fixed at a predetermined position by the holder 13. Have been. The venous blood flowing from the venous blood inlet 4 is supplied to the lower part of the venous blood filtration network 8 through the venous blood introduction pipe 7. The supplied blood flows out of the blood outlet 6 after being filtered by the venous blood filtration network 8. The venous blood filtration network 8 functions as a filter for removing foreign substances and bubbles in blood. As a constituent material of the venous blood filtration network 8, a metal material such as aluminum or stainless steel, a plastic, or a combination thereof can be used, and polyester, polypropylene, polyethylene, or stainless steel is particularly preferable.

As shown in FIG. 2, the venous blood filtration network 8 is fixed and supported on a lattice-shaped frame 9. In the upper part of the housing 2, an intracardiac blood filtration and defoaming part 10 and a defoaming member 11 are installed. The intracardiac blood flowing from the intracardiac blood inlet 5 is supplied to the inside of the venous blood filtration network 8 after foreign substances and bubbles are removed by the intracardiac blood filtration and defoaming unit 10. The defoaming member 11 is made of urethane foam, and is coated with an antifoaming agent. Reference numeral 12 denotes an air vent communicating with the blood storage chamber 3, from which air after defoaming by the defoaming member 11 or the like is discharged to the outside. In addition, the inflow and outflow of air accompanying the increase and decrease of blood in the blood storage chamber 3 are performed through the air vent 12.

FIG. 3 is a sectional view showing a planar structure at a position indicated by BB in FIG. As shown in FIG. 3, the distal end of the venous blood introduction tube 7 is arranged so as to have a sufficient distance from the venous blood filtration network 8 to suppress disturbance of blood flow in the blood reservoir. You.

With regard to the blood reservoir having the above configuration,
Conditions for suppressing and removing bubbles and facilitating control of the blood storage surface were studied. That is, as the conditions for obtaining such a result, the opening size of the mesh of the venous blood filtration network 8 and the distance between the tip of the venous blood introduction tube 7 and the venous blood filtration network 8 are set to appropriate values. We thought that it was necessary, and conducted an experiment to determine the setting range.

1) Opening size Regarding the opening size of the venous blood filtration network 8,
In order to check the upper limit, an experiment using the apparatus shown in FIG. 4 was performed. In FIG. 4, reference numeral 1 denotes a blood reservoir having the above configuration. Reference numeral 40 denotes a blood reservoir, which contains citrated or heparinized bovine blood Ht 35% (referred to as experimental blood). The experimental blood stored in the blood storage container 40 is supplied to the pump 4
The blood reservoir 42, the blood reservoir 1, and the air trap 43 are circulated by 1 and 44. However,
From the blood reservoir 42, the blood is supplied to the blood reservoir 1 by a head. In addition, air is mixed while the liquid is sent from the blood storage container 42 to the blood storage tank 1.

The flow rate of the experimental blood was 4 L / min, the amount of air mixed was 1 L / min, and the circulation time was 60 minutes. The amount of blood stored in the blood reservoir 1 was 200 mL (minimum blood storage level). After circulating under these conditions, the amount of air collected from the air trap 43 was measured as the amount of bubbles sent. As a result of measurement in which the opening size was changed, it was found that, when the opening size exceeded 55 μm, the amount of bubbles fed rapidly increased.

On the other hand, with respect to the lower limit of the opening size, an experiment was conducted in which the experimental blood was circulated at a higher flow rate than the above using the same apparatus as in FIG. At that time, blood reservoir 1
The control was performed so that the liquid level in the sample did not exceed an appropriate range, the opening size was changed, and the stability of the control was confirmed at each set value of the opening size. As a result, when the opening size was smaller than 20 μm, the control of the liquid level became extremely unstable. The reason is that when the opening size is smaller than 20 μm, the blood filtration resistance increases, and the dynamic filling amount of blood in the venous blood filtration network 8 increases.

Based on the above results, the practically suitable range of the opening size of the venous blood filtration network 8 is 20
５５55 μm. When it is smaller than 20 μm, it is difficult to control the liquid level. On the other hand, when it is larger than 55 μm, bubbles are easily removed, and the filtration performance becomes insufficient.

2) Distance between tip of venous blood introduction tube 7 and venous blood filtration network 8 Using venous blood filtration network 8 having an opening size within the above range, change distance s shown in FIG. Then, an experiment was performed to observe the occurrence of turbulence in the blood flow in the blood reservoir.

As a result of experiments, it has been found that good results can be obtained if the horizontal distance s between the tip of the venous blood introduction tube 7 and the venous blood filtration network 8 is set to 7 mm or more. With such a setting, the tip of the venous blood introduction tube 7 and the venous blood filtration network 8
Can be large enough to suppress the generation of turbulence due to the supplied venous blood, and the bubbles in the blood are unlikely to collide with each other, so that the generation of bubbles is small. Furthermore, the air bubbles that have flowed in along with the venous blood can rise to the liquid level before adhering to the surface of the venous blood filtration network 8, and the passage of the air bubbles from the venous blood filtration network 8 is reduced.

Note that the vertical distance between the tip of the venous blood introduction tube 7 and the bottom of the venous blood filtration network 8 is usually sufficiently larger than the horizontal distance s (for example, 33 mm), so that the above condition is satisfied. Is done.

As described above, the distance between the tip of the venous blood introduction tube 7 and the venous blood filtration network 8 is 7 mm or more, and the opening size of the venous blood filtration network 8 is 20 to 55 mm.
μm is the optimum condition for suppressing and removing air bubbles and easily controlling the blood storage surface. That is, since the turbulence of the blood flow in the blood reservoir is small, the flow velocity is slow, and the residence time of the blood is long, the outflow of air bubbles downstream of the blood reservoir is sufficiently reduced.

If the above-mentioned set value for the distance between the tip of the venous blood introduction tube 7 and the venous blood filtration network 8 is satisfied,
On the premise of the above-mentioned set value of the opening size of the mesh of the venous blood filtration network 8, good results were obtained even when the blood flow velocity was the maximum value normally predicted.

[0026]

According to the venous blood storage tank with cardiotomy of the present invention, the air bubbles flowing into the blood storage tank are appropriately removed without flowing out downstream of the blood storage tank, and the control of the blood storage surface is easy. is there.

[Brief description of the drawings]

FIG. 1 is a front view showing a venous blood reservoir with cardiotomy according to an embodiment of the present invention.

FIG. 2 is a side sectional view at a position indicated by AA in the blood reservoir of FIG. 1;

FIG. 3 is a plan sectional view at a position indicated by BB in the blood reservoir of FIG. 1;

FIG. 4 is a schematic diagram showing an experimental device for examining an appropriate range of the opening size of the mesh of the venous blood filtration network.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blood storage tank 2 housing 3 blood storage chamber 4 venous blood inlet 5 intracardiac blood inlet 6 blood outlet 7 venous blood introduction tube 8 venous blood filtration network 9 frame 10 intracardiac blood filtration defoamer 11 defoaming member 12 air vent 13 Holder 40, 42 Blood storage container 41, 44 Pump 43 Air trap

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Yoshida 12-17 Kakocho, Naka-ku, Hiroshima-shi, Hiroshima FMS term in JMS Co., Ltd. 4C077 AA11 BB02 BB10 CC04 DD13 EE01 KK19 KK25 NN01 PP14

Claims (1)

[Claims] 1. A housing having a venous blood inlet, an intracardiac blood inlet, and a blood outlet, and a housing extending from a bottom to an upper part of the housing and connected to the venous blood inlet and the intracardiac blood inlet. A venous blood filtration network installed so as to communicate with a venous blood introduction tube connected to the venous blood inflow port and having a tip extending to near the bottom in the venous blood filtration network,
An antifoaming member installed above the venous blood filtration network and carrying an antifoaming agent, and an intracardiac blood filtering and antifoaming unit installed above the antifoaming member and communicating with the intracardiac blood inlet port, The distance between the tip of the venous blood introduction tube and the venous blood filtration network is 7
mm, and the opening size of the venous blood filtration network is 20 to 55 μm.