JPS59103670A - Hollow yarn type artificial lung - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hollow fiber oxygenator using a hollow fiber membrane.

Conventionally known artificial lungs can be broadly classified into bubble-type and model-type, but recently model-type oxygenators have been recommended because they cause less damage to the blood.

Generally, this artificial lung model uses a flat membrane made of silicone rubber to supply oxygen to one side of the flat membrane.
By supplying blood to the other side, oxygen and carbon dioxide are exchanged through the flat membrane.

However, since this type of device uses a flat film, the device itself becomes large. In addition, the flat membrane is easily damaged by contact with the membrane support, and its strength is unstable, and great care must be taken in its handling.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to improve gas exchange efficiency, have stronger membrane strength than flat membranes, and have a compact structure that makes it easy to handle. The object of the present invention is to provide a hollow fiber oxygenator that is easy to use.

The object that achieves the above object includes a housing, and the inner diameter of the housing is about 100 to 1,000 mm.
000μ, wall thickness approximately 10 to 50μ, porosity approximately 20 to 8
a hollow fiber bundle consisting of a large number of hollow fiber membranes for gas exchange made of porous polyolefin needle resin having 0.0% porosity, and an oxygen chamber formed between the outer surface of each hollow fiber membrane and the inner surface of the housing; an inlet and an outlet communicating with the oxygen chamber;
a partition that supports each end of the hollow fiber membrane and isolates the open end of the hollow fiber membrane from the oxygen chamber; a blood inlet and an outlet that communicate with the internal space of each hollow fiber membrane; and the housing. and a restraining portion provided on the inner surface or the inner surface to narrow the periphery of the intermediate portion of the hollow fiber bundle.

Furthermore, the hollow fiber oxygenator has the surface of the hollow fiber membrane that comes into contact with blood coated with an antithrombotic material. Preferably, the hollow fiber membrane is a hollow fiber type oxygenator having an average diameter of about 200 to 1000 people.More preferably, the filling rate of the hollow fiber membrane is about 60 to 80% in the constriction part and about 30% in the other housing. ~60% hollow fiber oxygenator.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 indicates a housing for a hollow fiber oxygenator, and this housing 1 has annular covers 3 and 4 attached to the end of a cylindrical body 2, respectively, and inside this housing 1, A large number spread throughout, for example 10,000 ~
60,000 hollow fiber membranes 5 for gas exchange are arranged in parallel. And this hollow fiber for gas exchange 1! i15
The ends are each supported by a partition 6.7 in the mounting cover 3.4. In addition, the partition wall 6.7
closes the oxygen chamber 8 formed between the outer peripheral surface of the hollow fiber membrane 5 and the inner surface of the housing 1, and also closes the blood circulation space (not shown) formed from the inside of the hollow fiber membrane 5 for gas exchange. This is to isolate the oxygen chamber 8 from the oxygen chamber 8.

Note that in one case, the cover 3 is provided with an inlet 9 for supplying oxygen, and in the other case, the cover 4 is provided with an outlet lo for discharging the gas in the oxygen chamber 8.

On the other hand, the outer surfaces of the partition walls 6 and 7 are respectively covered with navel covers.
11 and 12, respectively, and a blood inflow chamber 13 and blood outflow chamber 14 are formed between the inner surfaces of the head covers 11 and 12 and the surface of the partition wall 6.7, respectively. Furthermore, a blood inlet 15 is formed in the head cover 11, and a blood outlet 16 is formed in the head cover 12.

Furthermore, on the inner surface of the cylindrical body 2 of the housing 1, there is provided a restricting portion 17 for aperture that protrudes from the center in the axial direction. That is, the restraint part 17 is formed integrally with the inner surface of the cylindrical body 2, and tightens the outer periphery of the hollow fiber bundle 18 made up of a large number of hollow fiber membranes 5 inserted into the cylindrical body 2. It looks like this. However, the above hollow fiber bundle 1
8 is constricted at the center in the axial direction to form a constricted portion 19, as shown in FIG. Therefore, the filling rate of the hollow fiber membrane 5 differs in each part along the axial direction, and is highest in the central part. Note that, for reasons to be described later, the desirable filling rate of each part is as follows. First, the filling rate in the central constriction section 19 is approximately 60 to 80%.
, the filling rate in the other parts 2 is about 30 to 60%, and the filling rate at both ends of the hollow fiber bundle 18, that is, on the outer surfaces of the partition walls 6 and 7, is about 20 to 40%.

Next, the hollow fiber membrane 5 for gas exchange and the partition wall 6.degree. 7 will be described. First, the hollow fiber membrane 5 is made of porous polyolefin resin, such as polypropylene or polyethylene.

Particularly suitable is polypropylene. This hollow fiber membrane 5 has a large number of pores communicating between the inside and outside of the wall. The inner diameter is about 100-1000μ, the wall thickness is about 10-50μ, the average pore diameter is about 200-1000μ,
And the porosity is about 20 to 80%. therefore.

Unlike conventional silicone film formation, where gas movement occurs through dissolution and diffusion, gas movement occurs as a volumetric flow, so there is less membrane resistance during gas movement, and its gas exchange performance is significantly improved. be.

By the way, when blood is flowed into the internal space of the hollow fiber membrane 5 to perform gas exchange, the inner diameter becomes a particular problem. Generally, when the inner diameter is about 100 μm or less, hydrodynamic resistance becomes large and clogging is likely to occur. For this reason, it is desirable that the inner diameter be larger than this. On the other hand, the upper limit of the inner diameter was able to be determined through experiments and will be described here.

Wall thickness: 30μ, pore weight: 45-50%, average pore diameter: approximately 50
We measured the relationship between blood volume and oxygenation capacity, and blood volume and oxygen saturation at the outlet of the artificial lung for three types of polypropylene hollow fiber membranes with inner diameters of approximately 200μ, approximately 300μ, and approximately 400μ, respectively, from 0 to 650 people. The results are shown in Figures 2 and 3.
The results were obtained as shown in the figure. Note that the oxygen saturation of the blood sent to this device at the inlet of the artificial lung is approximately 60%.

According to the results shown in Figure 2, which shows the relationship between blood volume and oxygenation capacity, it is clear that for a given blood volume per minute for a membrane area of 1 I, the one with an inner diameter of 200μ gives the best results, and the larger the inner diameter. It shows that it gets worse as the condition increases. Furthermore, based on the results shown in Figure 3, which shows the relationship between blood flow and oxygen saturation at the outlet of the artificial lung, a blood volume of 41/min is processed (
It is necessary to process something like this before the trial. ) The membrane area, priming amount, and contact time of the hollow fiber membrane required for (the difference in oxygen saturation between the inlet and outlet ends of the hollow fiber membrane is 35% (a value practically required for an oxygenator)) Table 1 shows the required residence time of blood in the hollow fiber membrane for this purpose.

Table 1 According to Table 1, when the inner diameter exceeds about 400 μm, the contact time becomes significantly longer, and the amount of priming and film area also increase. As the membrane area increases, the scale of the device increases, the membrane cost increases, and water vapor evaporation in the blood increases.

Problems arise with adhesion of blood components, and if the amount of priming increases, it places a considerable burden on the patient.

From the above results, when blood is allowed to flow inside the hollow fiber membrane, it can be concluded that the practical range of the inner diameter is about 100 to 300 μm.

Furthermore, 1 hollow fiber Il! Other factors regarding the membrane pores of 1li5, ie, wall thickness, average pore diameter, and porosity, were determined to the above-mentioned values based on considerations such as gas permeation and membrane strength.

Furthermore, rather than using porous polypropylene, polyethylene, or the like as the material for the hollow fiber membrane 5 in the oxygenator, it is desirable to coat the surface that comes into contact with blood with an antithrombotic material. For example, materials such as polyalkyl sulfate/ethyl cellulose and polydimethylsiloxane, which have excellent gas permeability, are used to
Coat to about 20 μm.

In this case, the membrane pores should be covered to the extent that the gas permeability of the hollow fiber membrane 5 is not affected.

Water vapor transpiration in the blood can be prevented.

Also, while the oxygenator is operating, the pressure on the blood side of the deceased is higher than that on the oxygen side, but this may reverse for some reason. If like this.

There is a risk that microbubbles may flow into the blood, but if the membrane pores of the wax described above are coated with an antithrombotic material, this risk does not occur. Furthermore, it goes without saying that blood coagulation (occurrence of microclots)
It is also useful in preventing.

Next, the formation of the partition wall 6.7 will be described.

As described above, the partition walls 6 and 7 perform the important function of isolating the inside and outside of the hollow fiber membrane 5. Generally, this partition wall 6.7 is constructed by applying a highly polar polymer bottling agent such as polyurethane, silicone, or epoxy resin to the inner wall surface at both ends of the housing 1 using a centrifugal injection method. It is made by pouring from the outlet 16 side and hardening. Further, in detail, first, a large number of hollow fiber membranes 51. which are longer than the length of the housing 1. are prepared, and after sealing both open ends with a highly viscous resin, they are placed side by side in the cylindrical body 2 of the housing 1. After that, attach the hollow fiber membrane 56. with a cover (mold) having a diameter larger than that of the cover 3.4. completely covering each end of the
While rotating the housing 1 about the central axis of the housing 1, the inflow chamber 13. The polymer botting agent flows in from the outflow chamber 14 side. Once the resin has hardened after pouring,
Remove the cover and cut the outer end surface of the resin with a sharp knife to remove the hollow fiber membrane 54. The partition walls 6 and 7 are thus formed by exposing both open ends to the surface.

As mentioned above, the hollow fiber oxygenator is used, for example, in surgical procedures, and is placed in the middle of a blood circulation circuit (not shown) that takes blood from the patient's vena cava and returns the blood to the patient's aorta. will be installed. In addition, blood is usually 47! It is taken out at a flow rate of /min.

Therefore, when the 9 oxygenator is used, blood flows from the blood supply port 15 into the inflow chamber 13 and then from the open end facing the inflow chamber 13 to each hollow fiber membrane 5. .

The hollow fiber membrane 59. The water flows through the internal space toward the outflow chamber 14 side. Then, it is collected again on the outflow chamber 14 side and flows out through the blood outlet 16. On the other hand, since oxygen gas is supplied to the oxygen chamber 8 as described later, each hollow fiber membrane 50. Gas exchange takes place via. That is, the carbon dioxide gas in the blood moves to the oxygen chamber 8 side, and the oxygen gas in the oxygen chamber 8 side moves to the hollow fiber membrane 50. It moves into the blood within the body.

In this case, blood is transferred to each hollow fiber membrane 50. Since blood is regulated to flow uniformly into the internal space of the blood, channeling (unbalanced flow) of blood does not occur.

However, since the flow inside the oxygen chamber 8 is a gas flow, the gas exchange hollow fiber membrane 50. If the distribution of gas is not uniform, channeling will occur immediately, which will impede gas exchange. In the case of an oxygenator, the driving force for gas movement
= partial pressure difference between blood side and gas side) is approximately 680 for oxygen gas
The fin weighs 11g, and the carbon dioxide gas is approximately 46tmHg. Therefore, the channeling within the oxygen chamber 8 has a strong influence on the degree of movement of carbon dioxide gas.

However, in the above embodiment, since the central portion of the hollow fiber bundle 18 is squeezed by the restricting portion 17 and expanded at both ends, the hollow fiber membrane 58. As the filling rate of each hollow fiber membrane 53. increases, each hollow fiber membrane 53. is evenly distributed. Therefore, compared to the case where the constriction part 19 is not formed, a stable flow is formed in which the M gas is uniformly dispersed, and as a result, the exchange efficiency of oxygen and carbon dioxide gas is increased. Additionally, since the internal cross-sectional area of the housing 1 changes rapidly at the constricted portion 19 in the center, the flow velocity at this portion changes rapidly, resulting in turbulence in the flow and an effect of increasing the gas movement speed. .

Note that the hollow fiber membrane 58. The filling rate is about 60
It is desirable to set it to ~80%, and the reason for this is as follows. That is, if the filling rate is about 60% or less, there will be a portion where the restricting portion 17 cannot be narrowed down, and the hollow fiber membrane 5
1. The distribution becomes uneven, exceeding channeling and deteriorating performance. Furthermore, it becomes difficult to position the hollow fiber bundle 18 at the center of the cylindrical portion, which poses a processing problem. on the other hand,
When the filling rate is about 80% or more.

A hollow fiber membrane 50 in contact with the restraining portion 17. is pressed too hard and collapses, preventing blood from flowing, which not only reduces efficiency but also causes residual blood. Furthermore, processing hollow fiber bundle 1
This is because when inserting 8, it becomes difficult to work tightly.

In addition, the filling rate in the cylindrical body 2 was set to about 30% to 60%, but the reason for this is that if the filling rate is about 30% or less, the hollow fiber membrane 52. is biased within the cylindrical body 2.

As a result, exchange efficiency decreases. In addition, it becomes difficult to process. On the other hand, when the filling rate is about 60% or more, the hollow fiber membrane 51. Close contact between them occurs.

This is because it still has a negative effect on performance.

Moreover, the filling rate on the outer surface of the partition wall 6.7 is about 20 to 40
%, but the reason for this is that if the hollow fiber membrane is about 20% or less, the hollow fiber membrane 50. The distribution of open edges tends to be uneven due to processing,
As a result, problems such as uneven blood flow distribution and blood clots occur. On the other hand, when the filling rate is 40% or more, the hollow fiber membrane 50. This is because they come into close contact with each other, and some parts are not filled with the potting agent, which is the material of the partition walls 6.7, causing leaks.

In addition, in the above embodiment, only the restraining portion 17 was made not to partially protrude from the inner surface of the housing 1, but the present invention is not limited to this, and a ring-shaped member may be provided as a separate member. The inner diameter of the comb may be the smallest at the center, and may be tapered to become larger at both ends.

As explained above, in the present invention, the peripheral surface of the intermediate portion of a hollow fiber bundle consisting of a large number of hollow fiber membranes arranged in an oxygen chamber in a housing is narrowed by a constraint part, so that the hollow fiber bundle is narrowed around the narrowed part. The filling rate of the fiber membranes increases, and each hollow fiber membrane is uniformly dispersed. Therefore, as a result of forming a stable flow in which oxygen gas is uniformly dispersed, the exchange efficiency of oxygen and carbon dioxide gas is increased. Further, by providing the throttle restricting portion, a rapid change in flow velocity occurs in this portion, thereby promoting the movement of gas. Therefore, the above effects prevent the channeling phenomenon.

Uniform gas exchange can be performed on the entire surface of the hollow fiber membrane, and the gas exchange efficiency can be increased.

In addition, since the center part of the hollow fiber bundle is squeezed by the restricting part for squeezing and the hollow fiber membranes are distributed uniformly, a higher manufacturing system is not required compared to the case where the restricting part for restricting is not provided, and the manufacturing process is easier. becomes easier. For example, even if the distribution at both ends is relatively non-uniform, it can be made uniform overall.

Furthermore, since the hollow fiber oxygenator of the present invention has the above-described structure, it is compact overall and easy to handle, and unlike those using a flat membrane, it is possible to improve the strength. It has excellent practical effects.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a side sectional view of the oxygenator, FIG. 2 is a graph showing the relationship between the inner diameter of the hollow fiber membrane, oxygenation capacity, and blood volume, and FIG. The figure is a graph showing the relationship between the inner diameter of the hollow fiber membrane and the oxygen saturation and blood volume at the outlet of the artificial lung. 1. Housing, 2. Cylindrical body. 3.4... Installation is with a cover. 5.Hollow fiber membrane for gas exchange. 6.7... Bulkhead, 8... Oxygen chamber. 9...Entrance, 10...Exit. 11.12...Head cover. 13...Inflow chamber, 14...Outflow chamber. 15...Entrance, 16...Exit. 17...Restriction part, 18...Hollow fiber bundle. 19...Aperture section. Applicant: Chill Seven Co., Ltd.

Claims (5)

[Claims] (1) A housing with an inner diameter of about 100 to 1000μ and a wall thickness of about 10 to 50μ, which are arranged side by side in this housing.
μ, between a hollow fiber bundle consisting of a large number of hollow fiber membranes for gas exchange made of porous polyolefin resin having a porosity of about 20 to 80%, and the outer surface of each of the hollow fiber membranes and the inner surface of the housing. an oxygen chamber formed by the oxygen chamber; an inlet and an outlet communicating with the oxygen chamber; a partition wall that supports each end of the hollow fiber membrane and isolates the open end of the hollow fiber membrane from the oxygen chamber; A blood inlet and an outlet communicating with the internal space of the hollow fiber membrane, and a restraining portion provided on or on the inner surface of the housing to squeeze the periphery of the intermediate portion of the hollow fiber bundle, further comprising a blood inlet and an outlet communicating with the inner space of the hollow fiber membrane. A hollow fiber oxygenator characterized in that the contacting surface is coated with an antithrombotic material. (2) The hollow fiber oxygenator according to claim 1, wherein the hollow fiber membrane has an average diameter of about 200 to 1000 people. (3) The filling rate of the hollow fiber membrane is approximately 60 to 8 in the restraint part.
0%, and about 30 to 60% in the other housing. (4) The hollow fiber oxygenator according to claim 3, wherein the filling rate of the hollow fiber membrane within the partition wall is about 20 to 40%. (5) The hollow fiber oxygenator according to any one of claims 1 to 4, wherein the antithrombotic material is silicone.