JPS63267367A - Hollow yarn type oxygenator - Google Patents

Abstract

PURPOSE:To perform the perfusion of blood due to the head between a patient and an oxygenator and to enhance the oxygen adding capacity of the oxygenator, by constituting the oxygenator so that the inner diameter of the almost central part of a housing in the axial direction thereof is made min. and enlarged from the central part to both end parts thereof to change the outer diameter of a hollow yarn membrane bundle along the inner wall of the housing and the outer diameter of said hollow yarn membrane bundle is minimized at the almost central part thereof. CONSTITUTION:Blood is flowed in an oxygenator 11 from the blood inflow port 27 thereof and impinges against the outer walls of the hollow yarns 16 to flow through an annular blood flow passage 29 and rises through a blood chamber under the gravity given by a head. The inner diameter of the almost central part of a housing 15 receiving an aggregate 17 as a hollow yarn membrane bundle in the axial direction thereof is made min. and gradually enlarged from the almost central part thereof to both end part thereof while the outer diameter of the received aggregate 17 changes along the inner wall of the housing 15 and becomes min. at the almost central part thereof in the axial direction. Therefore, head perfusion is made possible by reducing the pressure drop of the oxygenator 11 and the oxygen adding capacity of the oxygenator 11 can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hollow fiber oxygenator that removes carbon dioxide from blood and adds oxygen to blood during extracorporeal blood circulation.

[Prior Art] Conventionally, a hollow fiber oxygenator used as a demolding oxygenator causes less blood damage such as hemolysis, protein denaturation, blood coagulation, and blood adhesion than a single-bubble oxygenator, and is mechanically less sensitive to living organisms. It is widely recognized as being non-palmative to the lungs.

FIG. 1 shows a blood circuit using a conventional hollow fiber oxygenator, where 1 is an oxygenator, 2 is a pump, 3 is a blood storage tank, and 4 is a heat exchanger. That is, when using the conventional hollow fiber oxygenator 1, the pump 2 is provided on the upstream side (venous side) of the oxygenator 1 when viewed in the blood flow direction.

[Problems to be Solved by the Invention] By the way, when the pump is not provided on the downstream side of the hollow fiber oxygenator in the blood flow direction, but is provided on the upstream side as described above, the following There are drawbacks.

■Human] When blood is forcibly sent towards the second lung, the internal pressure of the human lower lung increases, and ■Hollow fiber membrane and bulkhead material for supporting the hollow fiber membrane bundle (
There is a risk of peeling at the boundary with the potting material (potting material), which may cause blood to leak or blood cells to be destroyed.

■When returning blood from the oxygenator to the living body, it is preferable to use a pulsatile flow pump that pumps out blood at a timing similar to the heartbeat as it does not cause stress to the living body. If this pump is on the side, even if there is a pulsation when it leaves the pump, the pulsation disappears when it passes through the oxygenator, and there is no pulsation when it enters the living body.

■The blood discharged from the pump must be returned to the living body without introducing new air bubbles. However,
If an oxygenator is located downstream of the pump, there is a risk of air bubbles being trapped there.

Therefore, in order to solve the above-mentioned drawbacks (1) to (2), an oxygenator is provided upstream of the pump in the direction of blood flow, and blood perfusion in the oxygenator is achieved by the head difference between the patient and the oxygenator. It is desirable to perform so-called head perfusion.

Here, when performing L head perfusion, it is necessary to reduce the pressure loss in the circuit including the oxygenator, and it is necessary to flow blood outside the hollow fiber membrane housed in the housing and to It is possible to lower the packing density.

However, when the packing density of the hollow fiber membrane is lowered, blood flows on the surface of the hollow fiber membrane and blood flows away from the surface of the hollow fiber membrane, resulting in less oxygen in the blood flowing inside the housing. A concentration gradient is created, reducing the oxygen capacity of the oxygenator.

An object of the present invention is to enable blood perfusion due to the head difference between a patient and an artificial lung, that is, head perfusion, and to improve the oxygen capacity of the artificial lung.

[Means for Solving the Problems] The present invention comprises a hollow fiber membrane bundle made up of a large number of hollow fiber membranes, which is housed in a cylindrical housing, and a gas containing oxygen flows inside the hollow fiber membranes. The oxygenator is an oxygenator in which blood flows through the outside of a hollow fiber membrane, and the housing has a minimum inner diameter at a substantially central portion in the axial direction, and gradually increases in inner diameter from the substantially central portion to both ends. The outer diameter of the hollow fiber membrane bundle to be housed changes along the inner wall of the housing, and is configured to be smallest at a substantially central portion in the axial direction of the hollow fiber membrane bundle.

[Function] According to the present invention, the housing that accommodates the hollow fiber membrane bundle is configured such that the inner diameter at the substantially central portion in the axial direction is the minimum, and the inner diameter gradually increases from the substantially central portion to both ends,
The outer diameter of the hollow fiber membrane bundle to be accommodated changes along the inner wall of the housing, and is configured to be smallest at a substantially central portion in the axial direction of the hollow fiber membrane bundle. Therefore, the pressure loss within the oxygenator can be reduced, head perfusion can be performed, and the oxygen capacity of the oxygenator can be improved. This is due to the following reasons.

If the hollow fiber membrane bundles are arranged parallel to each other without being squeezed, blood flows parallel to the hollow fiber membranes, forming a laminar flow (see Figure 8 (A)). The flow rate of flowing blood is slow, and the further the distance from the hollow fiber membrane surface, the faster the blood flow rate, resulting in an undesirable oxygen concentration gradient in the blood. It is necessary to increase the packing density of the entire hollow fiber membrane bundle. However, although increasing the packing density improves oxygen addition, pressure loss increases and head perfusion cannot be performed.

Therefore, according to the present invention, by squeezing the middle part of the hollow fiber membrane bundle, the blood flow is not parallel to the axis of the hollow fiber membranes, but intersects them, as shown in FIG. 8(B). For this reason,
Turbulence occurs in the blood flow.

Laminar flow is not formed and oxygen addition is improved. Therefore, the packing density of the hollow fiber membrane can be lowered under conditions that ensure oxygen addition, and as a result, pressure loss can be lowered. This allows head perfusion without the use of a pump.

Note that the method of squeezing the hollow fiber membrane bundle is not to provide a protrusion as shown in FIG. 8(C) in the middle part of the housing, but to tighten the inner wall of the housing toward the middle part as shown in FIG. 8(D). It is best to gradually reduce the diameter.

This makes it possible to reduce the dead volume that does not contribute to gas exchange.

[Example] Fig. 2 is a circuit diagram showing a blood circuit to which the hollow fiber oxygenator according to the present invention is applied, and Fig. 3 is a sectional view showing an embodiment of the hollow fiber oxygenator according to the present invention. , Figure 4 is IV of Figure 3.
5 is a sectional view taken along line VV in FIG. 3, and FIG. 6 is a sectional view taken along line Vl-Vl in FIG. 3.

As shown in FIG. 2, a blood circuit to which the present invention is applied includes an artificial lung 11, a blood reservoir 12, and a blood storage tank 12 extending from the vein side to the artery side.
, a pump 13, and a heat exchanger 14 are installed in this order.

The oxygenator 11 is constructed as shown in FIGS. 3 to 6. That is, in the internal space of the cylindrical housing 15,
An assembly (hollow fiber membrane bundle) 17 of hollow fiber membranes 16 is housed. Both ends of the hollow fiber membrane 16 are held liquid-tightly in the housing 15 via partition walls 18 and 19 with both ends open. Headers 20.21 are joined to both ends of the housing 15. The inner surface of the header 20 and the partition wall 18 define a gas wave inlet chamber 22 that communicates with the inner space of the hollow fiber membrane 16, and the header 20 is formed with a gas inlet port 23 for gas containing oxygen. . header 2
1 and the partition wall 19.

A gas outflow chamber 24 communicating with the internal space of the hollow fiber membrane 16 is defined, and a gas outflow boat 25 containing oxygen is formed in the header 21 . That is, in one oxygenator 11, the gas inflow boat 23 also allows gases such as oxygen and air to be supplied into the hollow fiber membrane 16. Note that the header 21 is not particularly provided, and the hollow fiber 11'2 is not provided with the gas outflow chamber 24 and the gas outflow port 25.
The gas flowing out from 16 may be directly released into the atmosphere.

The partition walls 18 and 19, the inner surface of the housing 15, and the outer surface of the hollow fiber membrane 16 form a blood chamber 26, and a blood inflow port 27 and a blood outflow port are provided at both ends of the housing 15, respectively, and communicate with the blood chamber 26. A boat 28 is formed. That is, for the person 111+till, blood is allowed to flow around the hollow fiber membrane 16 in the blood chamber 26 in a turbulent state.

Here, the inner surface of the portion of the housing 15 where the blood inflow port 27 is provided is an inner surface that expands outward from the inner surface of the axially intermediate portion of the housing 15, and is An annular blood flow path 29 as shown in FIG. 5 is formed between the outer circumference and the blood flow path 29 so that blood can be smoothly distributed to each hollow fiber membrane 16 from the entire periphery of the assembly 17 facing the blood flow path 29. There is. The expanded inner surface of the housing 15 also provides a blood inflow port 27 for the assembly 17.
The blood wave path 29 facing the blood inflow port 27 has a larger flow path area. That is, the flow path area of the blood flow path 29 is determined by the blood inflow port 27.
The amount of blood distributed from the blood flow path 29 is made uniform in the circumferential direction of the assembly 17, and the flow rate of blood in the axial direction of the housing 15 within the blood chamber 26 is increased in the circumferential direction of the assembly 17. It is assumed that uniformity can be achieved.

Further, the inner surface of the portion of the housing 15 where the blood outflow port 28 is provided is an inner surface that expands outward from the inner surface of the intermediate portion of the housing 15, and is
As shown in FIG. 6, an annular blood flow channel 30 is formed between the outer circumference of the aggregate 17 of No. 6 and the outer circumference of the aggregate 17 facing the blood flow channel 30. From all around the
The introduction tube □□□ smoothly faces the blood outflow port 28.

Moreover, the expanded inner surface of the housing 15 is as follows.

A blood flow path 30 is arranged eccentrically in a direction including the blood outflow port 28 with respect to the aggregate 17 and faces the blood outflow port 28.
The flow path area is made larger. That is, blood wave path 3
By gradually increasing the flow path area of 0 toward the blood outflow port 28, the safety of the living body is ensured without making the volume of the housing 15 too large and causing an excessive amount of extracorporeal blood circulation (priming volume) from the living body. Below, the blood flow path 30
The amount of blood introduced into the blood chamber 26 is equalized in the circumferential direction of the assembly 17, and the blood flow 1j) directed in the axial direction of the housing 15 within the blood chamber 26 can be made uniform in the circumferential direction of the assembly 17.

Further, the housing 15 has a tapered shape in which the inner diameter is minimized at the substantially central portion in the axial direction, and the inner diameter gradually increases from the substantially central portion to both ends, so that the outer diameter of the aggregate 17 is adjusted along the inner wall of the housing 15. It is narrowed down so that it is smallest at approximately the center in the axial direction. That is, the artificial lung 11 uniformizes the flow of blood in the cross section of the assembly 17 by constricting the assembly 17 applied by the housing 15, and also reduces turbulence by changing the blood flow velocity in the axial direction of the assembly 17. This promotes the generation of a flow state and improves gas exchange efficiency. Note that the inner surface of the housing 15 is formed into the tapered shape, and
Since the tapered inner surface and the inner surface defining the serum flow path 29,30 are connected by a tapered connecting surface as shown, the air to be exhausted during priming can be drawn into the blood chamber 26. Housing 15 without stagnation
It moves smoothly along the inner surface of the air vent, and can be reliably ejected from an air vent port 31, which will be described later. In addition, when the inner surface of the housing 15A defining the blood chamber 26A has portions P1 and P2 that protrude discontinuously in the blood flow direction, as in the oxygenator 11A shown in FIG. Air flows through these protruding portions P1. The air is trapped by P2, making it impossible to completely exhaust the air from the blood chamber 26A.

Here, a microporous membrane is used as the hollow fiber membrane 16. That is, the hollow fiber membrane 16 is made of a porous polyolefin resin such as polypropylene or polyethylene, with polypropylene being particularly suitable. This hollow fiber membrane 16 has a large number of pores communicating between the inside and outside of the wall. The inner diameter of the pore is approximately 100-1
000 p-1 wall thickness is about 10-50, average pore diameter is about 2
00-2000 people and the porosity is 20-80%. When using the hollow fiber membrane 16 made of this microporous membrane, gas movement is performed as a volumetric membrane, so the membrane resistance in gas movement is reduced, making it possible to obtain high gas exchange performance. Note that the hollow fiber membrane 16 is not necessarily a microporous membrane, but may be one using a silicone membrane or the like that performs gas movement by dissolution and diffusion.

By the way, the partition walls 18 and 19 are formed by the following centrifugal injection method. That is, first, prepare a large number of hollow fiber membranes 16 that are longer than the length of the housing 15,
After sealing both open ends with a highly viscous resin, they are placed side by side in the housing 15. Thereafter, the housing 15 is rotated with both ends of the hollow fiber membrane 16 completely covered and the central axis of the housing 15 placed in the rotation center opening defined in the longitudinal direction of the housing 15 in the radial direction of rotation. At the same time, the polymer botting material is introduced from the blood inflow port 27 and the blood outflow port 28 side. After the resin has hardened after pouring, the outer end surface of the resin is cut with a sharp knife to expose both open ends of the hollow fiber membrane 16 to the surface, thereby forming partition walls 18 and 19. Therefore, the surface of the septum 18, 19 facing the blood chamber 26 becomes a cylindrical concave surface as shown in FIGS. 3 and 4.

In the above embodiment, the housing 15 is provided with an air vent port 31 that is located above the blood outflow port 28 and communicates with the inside of the blood chamber 26 under use. A removable breathable and bacteria-impermeable filter 32 is attached to the air vent port 31. It is removed during priming and attached after priming, and when the air generated during use of the oxygenator is vented, bacteria are removed from the oxygenator 11. During priming, the air vent port 31 releases the air inside the blood circuit and the artificial lung, which is removed by the filling fluid such as physiological saline, to the outside, and after evacuation,
It is equipped with a stopper and can be sealed airtight.

Next, the operation of the above embodiment will be explained.

The artificial lung is used, for example, in surgical procedures, and is installed in the middle of the blood circulation circuit (FIG. 2). Note that blood is usually taken out at a flow rate of 4 cycles/inch.

First, before blood flows into the artificial lung 11, physiological saline mixed with heparin is introduced from the blood inflow boat 28 to remove all the air in the blood chamber 26 within the artificial lung 11. At this time, connect the tube connected to the blood storage tank to the air purge boat 31 (remove the filter 32), and connect the tube to the blood outflow boat 28 in the same way as the air purge boat 31, or if not, use a cap etc. After the air in the oxygenator lung 11 is sealed, the filter 32 is attached to the air vent 31 and the cap (not shown) is placed on the cap (not shown). is caused to flow in from the blood inflow boat 27 of the oxygenator 11.

The inflowing blood hits the outer wall of the hollow fiber 16 near the blood inflow boat 27, flows through an annular blood flow path 29 provided inside one oxygenator, and moves up the blood chamber 26 due to the gravity given by the head. Further, a gas containing oxygen such as oxygen or air is supplied from the gas inflow boat 23 into the hollow fiber membrane 16 . This gas passes through the inside of the hollow fiber membrane 16,
The gas is discharged from the gas inflow boat 25 to the outside. At this time, the blood exchanges oxygen flowing from the gas inflow boat through the hollow fiber +1'J l 6 with carbon dioxide in the blood. Then, the oxygenated blood flows out from the blood outflow boat 28 through the blood flow path 30, is stored in the blood storage tank 12, and is heated or cooled to an appropriate temperature through the blood pump 13 and the heat exchanger 4. blood is sent to the human body.

According to the embodiment described above, the inner diameter of the housing 15 that houses the assembly 17 as a hollow fiber membrane bundle is minimized at approximately the center in the axial direction, and the inner diameter gradually increases from the approximately center to both ends. The outer diameter of the assembly 17 to be housed changes along the inner wall of the housing 15, and is configured to be smallest at approximately the center of the assembly 17 in the axial direction. Therefore, the pressure loss of the artificial lung 11 can be reduced, head perfusion can be performed, and the oxygen capacity of the artificial lung 11 can be improved.

That is, by squeezing the middle part of the aggregate 17, the blood flow is not parallel to the axis of the hollow fiber 1lI216, but intersects with it, as shown in FIG. 8(B). This causes turbulence in the blood flow, prevents the formation of a calendar, and improves oxygenation. Therefore, the packing density of the hollow fiber membranes 16 can be lowered under conditions that ensure oxygen addition, and as a result, pressure loss can be lowered. This allows head perfusion without the use of a pump.

Therefore, blood perfusion due to the head difference between the patient and the artificial lung 11, that is, head perfusion, can be made possible, and oxygenation of the artificial lung 11 can be directed.

[Effects of the Invention] As shown in L below, the present invention has a hollow fiber membrane bundle made up of a large number of hollow fiber membranes housed in a cylindrical housing, and a gas containing oxygen inside the hollow fiber membranes. An artificial lung in which blood flows outside the hollow fiber membrane, the housing having a minimum inner diameter at approximately the center in the axial direction, and gradually increasing the inner diameter from the approximately center to both ends. However, the outer diameter of the hollow fiber membrane bundle to be accommodated changes along the inner wall of the housing, and is configured to be smallest at approximately the center in the axial direction of the hollow fiber membrane bundle. Therefore, blood perfusion due to the head difference between the patient and the oxygenator, that is, head perfusion, can be made possible, and the oxygen capacity of the oxygenator can be improved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a blood circuit to which a conventional demolding oxygenator is applied, and FIG. 2 is a circuit diagram showing a blood circuit to which a hollow fiber oxygenator according to the present invention is applied. 3 is a cross-sectional view showing an embodiment of the hollow fiber oxygenator according to the present invention, FIG. 4 is a cross-sectional view taken along the line ■-■ in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 3. 6 is a cross-sectional view taken along Vl-Vl in Fig. 3.
7 is a sectional view showing a conventional hollow fiber oxygenator, and FIGS. 8(A) to 8(D) are schematic diagrams illustrating the present invention in detail. 11... Artificial lung, 15... Housing, 16... Hollow fiber membrane. 17...Aggregation, 18.19...Bulkhead, 23...Gas inflow boat. 26...Blood chamber, 27...Blood demon port, 28...Serum wave mountain boat, 29.30...Blood channel.

Claims (2)

[Claims] (1) An oxygenator in which a hollow fiber membrane bundle consisting of a large number of hollow fiber membranes is housed in a cylindrical housing, gas containing oxygen flows inside the hollow fiber membranes, and blood flows outside the hollow fiber membranes. The housing has a minimum inner diameter at approximately the center in the axial direction, and gradually increases the inner diameter from the approximately center to both ends, such that the outer diameter of the hollow fiber membrane bundle to be accommodated is the same. A hollow fiber oxygenator characterized in that the hollow fiber membrane bundle changes along the inner wall of the housing and becomes smallest at a substantially central portion in the axial direction of the hollow fiber membrane bundle. (2) The hollow fiber oxygenator according to claim 1, wherein the hollow fiber membrane is a microporous membrane.