JPH0357784B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention (1) Technical Field The present invention relates to an oxygenator that performs gas exchange using a porous membrane.

(2) Prior art and its problems For example, when performing cardiac surgery, an oxygenator is attached to an artificial heart-lung extracorporeal circulation circuit. As this artificial lung, one using a gas exchange membrane made of a porous membrane is known. In this case, blood and oxygen supply gas (oxygen-enriched gas) come into contact through the micropores in the porous membrane, so that the oxygen in the oxygen supply gas is supplied to the blood side, and at the same time, the carbon dioxide in the blood is is transferred to the oxygen supply gas side, and so-called gas exchange takes place.

However, the gas exchange membrane of this oxygenator cannot completely prevent the permeation of water vapor in the blood, so if this type of oxygenator is used for a long time,
Water vapor that permeates through the micropores on the gas passage side of the gas exchange membrane (inner wall for hollow fiber membranes) becomes condensed water.
It accumulated in the lower part of the oxygenator, blocking the micropores in that area and further blocking the gas passage formed by the gas exchange membrane, resulting in a significant decrease in the gas exchange ability of the oxygenator.

Therefore, the inventors of the present application investigated a method of removing the above-mentioned dew condensation water.

First, the first method is to increase the flow rate of gas flowing in from the gas inlet and use the resulting pressure to remove condensed water from the gas outlet. Although condensed water can be removed using this method, the differential pressure between the gas passage side and the blood passage side may exceed the bubble point of the porous membrane, and in this case, air bubbles flow into the blood side through the porous membrane. and is extremely dangerous.

The second method is to provide a suction means at the gas outlet to suction and remove the condensed water. According to this method, condensed water can be safely removed without introducing air bubbles into the blood.

Therefore, it was found that the second method described above is preferable.

However, when using the above method, the gas exhaust port cannot be opened because it is necessary to communicate the gas exhaust port with the suction means using a tube or the like.
Therefore, there is a risk that the gas outlet may be blocked by condensed water or the tube may become blocked due to bending of the communicating tube, effectively causing the gas outlet to become blocked, and in such a situation, the gas passage If the pressure increases and exceeds the bubble point, there is a risk that bubbles will flow into the blood.

Purpose of the Invention The purpose of the present invention is to solve the problems of the prior art described above, and to provide a suction circuit for safely and efficiently removing condensed water while avoiding the risk of air bubbles flowing into blood during extracorporeal circulation. The aim is to provide an artificial lung that can be used by attaching a

A device that achieves the above object includes a cylindrical housing, a gas exchange membrane formed of a porous membrane housed in the cylindrical housing and partitioning the inside of the cylindrical housing into a gas passage and a blood passage, and In an artificial lung having a gas inlet port having a gas inlet communicating with a passage, a gas outlet port having a gas outlet, and a blood inflow port and a blood outflow port communicating with the blood passage, the gas outlet port The artificial artificial body is provided with a valve that opens before the pressure difference between the gas passage and the blood passage exceeds the valve point of the porous membrane, and closes when the inside of the gas discharge side port becomes a negative pressure state. It's the lungs.

Furthermore, it is preferable that the valve is normally closed at atmospheric pressure and opens when pressure is applied to the gas discharge side port.

Further, it is preferable that the valve is normally open at atmospheric pressure and closed when the inside of the gas discharge side port becomes negative pressure.

Furthermore, it is preferable that the gas exchange membrane is a hollow fiber membrane bundle, a gas passage is formed inside the hollow fiber membrane, and a blood passage is formed from the outer wall of the hollow fiber membrane and the inside of the cylindrical housing.

DETAILED DESCRIPTION OF THE INVENTION The artificial lung of the present invention will be described in detail using embodiments shown in FIGS. 1 to 5.

The artificial lung 1 of the present invention includes a cylindrical housing 20,
A hollow fiber membrane 4, which is a gas exchange membrane formed from a porous membrane, is housed in the axial direction within the cylindrical housing 20.
and partition walls 12 and 13 that fluid-tightly hold both ends of the hollow fiber membrane 4 in the housing, and the inside of the cylindrical housing 20 is divided into a gas passage and a blood passage 3, Above the partition wall 12, which is a section, is a cap-shaped gas introduction side port 6 having a gas introduction port 5 that communicates with the gas passage, which is the internal space of the hollow fiber membrane 4; A cap-shaped gas exhaust side port 8 having a gas exhaust port 7 communicating with the internal space of the housing is attached.

The cylindrical housing 20 further includes a blood inflow port 9 and a blood outflow port 1 that communicate with the blood passageway 3.
It has 0. A valve 1 that communicates with or shuts off the inside of the port 8 and the outside is connected to the gas discharge side port 8.
1 is provided.

The porous membrane may be either the above-mentioned hollow fiber membrane or flat membrane, but preferably a hollow fiber membrane.

Therefore, the oxygenator 1 may be either a flat membrane type or a hollow fiber membrane type, or may be a normal type of oxygenator in which blood flows inside the hollow fibers. Preferably, the oxygenator is of the type that allows blood to flow outside the hollow fiber membrane as described above, and if this oxygenator is used, there is no need to provide a blood pump in front of the oxygenator in the circulation circuit because the pressure loss is small. Blood can be sent to the artificial lung by removing blood only by the drop from the human body.

The hollow fiber membrane 4 is a porous membrane, and has an inner diameter of 100~
1000μm, wall thickness 5-200μm, preferably 10-200μm
100μm, porosity 20-80%, preferably 30-60
%, and the pore diameter is 0.01 to 5 μm, preferably 0.01 to 5 μm.
It is 1 μm. Further, as the material used for the porous membrane, hydrophobic polymeric materials such as polypropylene, polyethylene, polysulfone, polyacrylonitrile, polytetrafluoroethylene, polyacrylonitrile, and cellulose acetate are used. Preferably, it is a polyolefin resin, particularly preferably polypropylene, and one in which micropores are formed in the wall by a stretching method or a solid-liquid layer separation method is more preferred.

The cylindrical housing 20 is formed of, for example, a cylindrical transparent body. The reason why it is made of transparent material is that it is easy to check the inside.

A large number of hollow fiber membranes 4 of about 5,000 to 100,000 are housed in the housing 20 in the axial direction. They are each fixed in a liquid-tight state by partition walls 12 and 13 in an open state. The partition walls 12 and 13 are made of polyurethane,
It is formed using a potting agent such as silicone rubber. A blood inflow port 9 and a blood outflow port 10 are provided near both ends of the housing 20.
Therefore, the partition walls 12 and 13 inside the housing 20
The portion sandwiched between them is partitioned into a gas passage inside the hollow fiber membrane 4 and a blood passage 3 outside the hollow fiber membrane 4.

A gas inlet port 6 having a gas inlet 5 is attached to the outside of the partition wall 12, and a gas outlet port 8 having a gas outlet 7 is attached to the outside of the partition wall 13. This is done using a ring 15. Further, without using a tightening ring, the housing 20 may be fused using ultrasonic waves, high frequencies, etc., bonded using an adhesive, or mechanically fitted.

A valve 11 is attached to the gas discharge side port 8 to communicate or cut off communication between the inside of the port and the outside. The valve 11 is opened before the pressure difference between the gas passage and the blood passage exceeds the bubble point of the porous membrane forming the gas exchange membrane.
The valve is also closed when the inside of the gas discharge side port becomes negative pressure.

The bubble point of a porous membrane is the differential pressure between the gas and liquid sides when air bubbles flow into the liquid side from the porous membrane when gas is brought into contact with one side of the porous membrane and liquid is brought into contact with the other side. means. In other words, valve 11
is opened at least before air bubbles flow from the gas passage side to the blood passage side via the porous membrane during use of the oxygenator.

The bubble point differs depending on the porous membrane.

There are two possible valve configurations that satisfy the above conditions.

The first type is a type that is closed in a normal state, that is, when gas is flowing in and the gas outlet is not blocked, and opens when the gas outlet is blocked. In this case, the valve 11 must open before the differential pressure between the gas passage and the blood passage exceeds the bubble point of the gas exchange membrane. By providing such a valve 11, it opens when the gas outlet is blocked for some reason, or when the tube of the condensed water suction means attached to the gas outlet bends and becomes blocked, and the internal pressure of the gas passage increases. .

The structure of the valve used in the first embodiment may be of any type as long as it functions as described above. The bubble point of a porous membrane is approximately 10 to 10 ³ cmAq, the pressure on the blood passage side is usually about 0 to 50 cmAq, and the pressure on the gas passage side is usually 0 to 10 cmAq.
That's about it. Therefore, it is preferable that the valve opens when the pressure inside the gas discharge side port becomes 10 cmAq or more, or more safely, 5 cmAq or more.

As shown in FIGS. 2 and 3, a valve that is closed in the normal state and opens at the pressure described above has a hole 34 in the gas discharge side port and a flexible valve that covers the hole 34. A valve member 36 made of a flexible material (for example, a rubber such as silicone rubber or latex rubber, or an elastomer such as a polyolefin elastomer, a polyamide elastomer, or a polyurethane elastomer) is fixed to the surface of the gas discharge side port. Further, the fixation is performed not over the entire circumference of the valve member 36 but only on a portion thereof. Thus, the valve member 36 can be opened in the unsecured portion. Further, the valve 11 is not limited to the above-mentioned form,
For example, instead of the valve member described above, a valve member made of a hard material is fixed to the gas discharge side port with a hinge, and the valve member is further pressed against the hinge portion in the closing direction, and the pressure inside the gas discharge side port is reduced. 10cm
A valve with a spring that opens when the pressure exceeds Aq, or more safely, 5 cmAq or above, and a spherical valve member that closes the hole of the gas discharge side port instead of the above-mentioned valve member. A valve that contains a spring that presses the valve member against the hole in the port, and is further provided with a rib that protrudes outward around the entire circumference of the hole in the gas discharge side port, and is made of a hard member that contacts the entire circumference of the rib and closes the hole. It is conceivable that the member is fixed using a plurality of springs that connect the gas discharge side port and the valve member.

The second form is open in the normal state, that is, when gas is flowing in and the gas outlet is not blocked, and is closed when the suction means is activated and the inside of the gas outlet port becomes negative pressure. It is of type. In this case, it is necessary that the valve 11 closes when the pressure inside the gas discharge side port becomes lower than atmospheric pressure to some extent. By providing such a valve, it is open under normal conditions, so
Even if the gas outlet is blocked for some reason or the tube of the condensed water suction means attached to the gas outlet is bent and blocked, the pressure inside the gas outlet port will not increase and air bubbles will flow into the blood. There's nothing to do.

Furthermore, since it is closed when the suction means is activated to remove condensed water, it is possible to reliably remove condensed water. The structure of the valve used in the second embodiment may be any structure as long as it functions as described above.
Normally, the pressure inside the gas exhaust port is approximately equal to atmospheric pressure, and when the suction means is activated to suck up condensed water, the pressure inside the gas exhaust port is −
5 to 1000 cmAq, which is lower than atmospheric pressure,
The internal pressure of the valve on the gas discharge side is 5cmAq below atmospheric pressure.
More reliably, it is preferable that the occlusion occurs when the temperature drops to 1 cmAq or more. As shown in FIGS. 4 and 5, the valve that is open under normal conditions and closed when the above pressure is reached is provided with a hole 34 in the gas discharge side port.
A plurality of spacers 38 are spaced apart (preferably equally spaced) and fixed at positions slightly apart from each other to surround the hole 34. Further, a valve member 36 made of a flexible material (for example, a rubber such as silicone rubber or latex rubber, or an elastomer such as polyolefin elastomer, polyamide elastomer, or polyurethane elastomer) is fixed onto the spacer. Therefore, the valve is open in the area where there is no spacer. In addition, the valve member 36 has a recessed hole 34 in the gas discharge side port when the pressure inside the gas discharge side port becomes lower than atmospheric pressure by 5 cmAq, more certainly by 1 cmAq or more.
occlude.

Moreover, the valve is not limited to the above-mentioned form, for example,
Instead of the above-mentioned valve member, a valve member made of a hard member is fixed to the gas discharge side port with a hinge, and the valve member is pulled on the hinge portion in the direction of opening, and the inside of the gas discharge side port is made large. 5cmAq from atmospheric pressure,
More reliably, a spring is provided that closes the hole with a valve member when the temperature drops to 1 cmAq or more, and a spherical valve member that can close the hole of the gas discharge side port in place of the valve member and its valve. It houses a spring that grips the member to prevent the hole from being blocked in the normal state, and a rib that protrudes outward is provided around the entire circumference of the hole of the gas discharge side port, and this rib is in contact with the entire circumference to prevent the hole from being blocked. It is conceivable that a valve member made of a flexible hard material is fixed to the gas discharge side port and the valve member using a plurality of springs that connect the valve member so that the valve member does not close the hole in a normal state.

Moreover, the position of the valve 11 may be any position as long as it is a gas discharge side port.

Next, the condensed water suction means used by being attached to the gas discharge port 7 will be explained.

The suction means consists of a trap 22, a tube 24 that communicates the trap 22 and the gas outlet 7, a suction device 26, and a connecting tube 28 that connects the suction device 26 and the trap 22.
The trap 22 is for capturing and storing condensed water removed from the oxygenator 1. Suction device 2
Reference numeral 6 is equipped with, for example, a pump, which makes the inside of the gas discharge side port 8 negative pressure, generates a negative-pressure high-flow airflow in the gas passage, and sucks the condensed water inside to the trap 22. The suction device 26 is located in the gas passage.
It is preferable to have the ability to generate an airflow of 1/min or more.

Further, the gas inlet 5 is an air inlet port 3 having a valve (for example, a manual opening/closing valve) 32 in the middle of communicating with an oxygen enriched gas supply device (not shown).
It is preferable to provide 0. This is because when the above-mentioned suction means is operated, by opening the valve 32 without removing the oxygen-enriched gas supply device from the gas inlet, the inside of the gas passage can be reliably brought to negative pressure. Further, this air introduction port 30 may be directly attached to the gas introduction side port 6. In this case, the gas introduction side port 6 is provided with an air introduction port 30 in addition to the gas introduction port 5.

Next, an embodiment of the artificial lung of the present invention will be described.

Example 1 Approximately 50,000 porous hollow fiber membranes (inner diameter 150 μm, outer diameter 240 μm) were housed in a cylindrical housing (inner diameter 80 mm), and both ends were fixed to the housing in a liquid-tight manner using polyurethane. The membrane area of the oxygenator was approximately 3 m ² . A gas introduction side port was attached to one side of the partition wall formed of polyurethane using a tightening ring.

In addition, as shown in Figures 2 and 3, the other partition wall has a hole with a diameter of 7 mm, and the hole is covered with a semi-elliptical shape (the length of the straight part is approximately 20 mm, and the length of the straight part is approximately 20 mm). The valve member is made of silicone rubber (thickness: 3mm) with a length of about 20mm to the top of the valve member, and about 3mm from the end of the straight part is attached to the surface of the gas discharge side port using room temperature curing silicone rubber. The stuck gas exhaust port was attached using a tightening ring. Note that the valve could be opened in the unfixed portion.

Using this artificial lung, oxygen-enriched gas was allowed to flow in from the gas inlet at a rate of 10/min, and bovine blood was allowed to flow in from the blood inlet port at a rate of 5/min, and the gas outlet was closed by hand. At that time, the valve was opened and no air bubbles were allowed to flow into the bovine blood.

Example 2 The same structure as in Example 1 was used except for the valve provided at the gas discharge side port.

As shown in Fig. 4 and Fig. 5, the valve is provided with a hole in the gas discharge side port, and a 6mm hole is placed around the hole at a position approximately 10 mm away from the center of the hole.
Spacers (about 1 mm thick) were fixed at regular intervals, and a disk-shaped valve member (about 30 mm in diameter) made of silicone rubber was fixed on top of the spacers. This valve is open where there is no spacer.

Using this artificial lung, oxygen-enriched gas was allowed to flow in at 3/min from the gas inlet, and bovine blood was allowed to flow in at 3/min from the blood inflow port. After about 4 hours, condensed water was observed inside the oxygenator. Therefore, a suction means was attached to the gas discharge port of the gas discharge side port and the suction device was activated.

At this time, the valve attached to the gas inlet was opened. It is thought that the operation of this suction device generates an airflow of about 20/min in the gas passage. Further, when the pressure inside the gas exhaust port at this time reached approximately -10 cmAq, the valve member was able to close the recessed hole on the gas exhaust side port side and remove the condensed water.

Specific Effects of the Invention The oxygenator 1 of the present invention is installed in an extracorporeal circulation circuit, and blood flowing in from the blood inflow port 9 of the oxygenator 1 is formed between the housing 20 and the hollow fiber membrane 4 which is a gas exchange membrane. Carbon dioxide is removed and oxygen is added while passing through the blood passageway 3. At this time, gas containing oxygen is flowed from the gas inlet 5 into the hollow fiber membrane 4, which is a gas exchange membrane. When the gas outlet 7 is blocked for some reason, the gas is discharged from the valve 11 of the gas outlet port 8, so the pressure in the gas passage does not become too high and the gas is discharged through the hollow fiber membrane 4. No air bubbles enter the blood. In addition, when the suction means attached to the gas outlet 7 is in operation to remove condensed water generated in the gas passage of the oxygenator, the valve 1 is
1 is closed so that condensed water can be removed reliably.

Specific Effects of the Invention The artificial lung of the present invention includes a cylindrical housing and a gas exchange membrane formed of a porous membrane housed within the cylindrical housing and partitioning the inside of the cylindrical housing into a gas passage and a blood passage. and an oxygenator having a gas inlet port having a gas inlet that communicates with the gas passage, a gas outlet port having a gas outlet, and a blood inflow port and a blood outflow port that communicate with the blood passage. A valve that opens before the differential pressure between the gas passage and the blood passage exceeds the valve point of the porous membrane at the gas exhaust side port, and closes when the inside of the gas exhaust side port becomes a negative pressure state. This artificial lung is equipped with a suction means to safely and efficiently remove condensed water, avoiding the risk of air bubbles flowing into the blood during extracorporeal circulation.

Furthermore, if the valve is normally closed at atmospheric pressure and opens when pressure is applied to the gas exhaust port, it will prevent the gas exhaust port from closing when the gas exhaust port is blocked for some reason. Since the tube of the attached dew water suction means is bent and closed and opened when the internal pressure of the gas passage increases, it is possible to reliably avoid the risk of air bubbles flowing into the blood during extracorporeal circulation.

In addition, if the valve is normally open at atmospheric pressure and closes when the inside of the gas exhaust port becomes negative pressure, the valve will be closed when the gas exhaust port is blocked for some reason and the gas exhaust port will close. Even if the tube of the attached dew water suction means is bent and blocked, the gas flows out from the valve, so the pressure in the gas passage does not increase and no air bubbles flow into the blood. Further, when the suction means is operated to remove condensed water, the valve is closed, so that condensed water can be reliably removed.

Furthermore, if the gas exchange membrane is a hollow fiber membrane bundle, a gas passage is formed inside the hollow fiber membrane, and a blood passage is formed between the outer wall of the hollow fiber membrane and the inside of the cylindrical housing, the pressure loss Since the amount of blood is small, there is no need to provide a blood pump in front of the oxygenator in the circulation circuit, and blood can be sent to the oxygenator by removing blood only by the drop from the human body.

[Brief explanation of drawings]

FIG. 1 is a cutaway side view showing an artificial lung according to an embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of a gas discharge side port having a valve used in the artificial lung of the present invention.
FIG. 3 is a cross-sectional view showing the valve portion of the gas exhaust side port in FIG. 2, FIG. FIG. 5 is a sectional view showing the valve portion of the gas discharge side port in FIG. 4. 1... Artificial lung, 3... Blood passage, 4... Hollow fiber membrane, 5... Gas inlet, 6... Gas inlet port, 7... Gas outlet, 8... Gas outlet port, 9 ... Blood inflow port, 10 ... Blood outflow port, 11 ... Valve, 20 ... Cylindrical housing, 2
6... Suction device, 30... Air introduction port, 34
...hole, 36...valve member.

Claims (1)

[Scope of Claims] 1. A cylindrical housing, a gas exchange membrane formed of a porous membrane housed within the cylindrical housing and partitioning the inside of the cylindrical housing into a gas passage and a blood passage, and the gas passage. In the oxygenator, the oxygenator has a gas inlet port having a gas inlet communicating with the oxygen source, a gas outlet port having a gas outlet communicating with the blood passageway, and a blood inflow port and a blood outflow port communicating with the blood passageway, A valve is provided that opens before the differential pressure between the gas passage and the blood passage exceeds a bubble point of the porous membrane and closes when the inside of the gas discharge side port becomes a negative pressure state. Characteristic artificial lung. 2. The artificial lung according to claim 1, wherein the valve is normally closed at atmospheric pressure and opens when pressure is applied inside the gas discharge port. 3. The artificial lung according to claim 1, wherein the valve is normally open at atmospheric pressure and is closed when the inside of the gas discharge port becomes negative pressure. 4. The gas exchange membrane is a hollow fiber membrane bundle, a gas passage is formed inside the hollow fiber membrane, and a blood passage is formed between the outer wall of the hollow fiber membrane and the inside of the cylindrical housing. The artificial lung according to any of paragraph 3.