Medical instrument

An Oxygenator as a medical instrument includes at least one first hollow fiber membrane layer comprised of a plurality of integrated first hollow fiber membranes, and forms a shape of a cylindrical body as a whole, and at least one second hollow fiber membrane layer disposed at the outer circumferential side of the first hollow fiber membrane layer in a state of being concentric with the first hollow fiber membrane layer, has a plurality of integrated second hollow fiber membranes, and forms a shape of a cylindrical body as a whole. Moreover, each of the first hollow fiber membranes is wound around a central axis, and each of the second hollow fiber membranes is wound around a central axis. The number of times the second hollow fiber membranes are wound is smaller than the number of times the first hollow fiber membranes are wound.

TECHNICAL FIELD

The present invention relates to a medical instrument.

BACKGROUND DISCUSSION

In the related art, an Oxygenator which performs gas exchange using a hollow fiber membrane layer constituted with a plurality of hollow fiber membranes is known (for example, see U.S. Pat. No. 6,503,451).

The Oxygenator described in U.S. Pat. No. 6,503,451 has a housing, hollow fiber membrane layers which are housed in the housing and form a cylindrical shape as a whole, a blood inlet, a blood outlet, a gas inlet, and a gas outlet. In the Oxygenator, through each hollow fiber membrane, gas exchange between blood and gas, (i.e., a process of adding oxygen and removing carbon dioxide) occurs.

In the hollow fiber membrane layers having a shape of a cylindrical body, a plurality of hollow fiber membranes are integrated and laminated on one another. In each of the layers, hollow fiber membranes are wound one by one around the central axis of the cylindrical body, and in this state, the hollow fiber membranes travel between a partition at one end of the cylindrical body and a partition at the other end of the cylindrical body. In an outward path heading for the partition at the other end from the partition at one end, each hollow fiber membrane is wound at least once around the central axis of the cylindrical body. Moreover, in a homeward path heading for the partition at one end from the partition at the other end, each hollow fiber membrane is also wound at least once around the central axis of the cylindrical body.

In each of the hollow fiber membranes wound as above, a length of the layer wound once around the central axis of the cylindrical body increases toward the outer circumference of the cylindrical hollow fiber membrane layer. The Oxygenator has a problem in that the larger the length of the hollow fiber membrane from one partition to the other partition is, the greater the pressure loss of gas passing through the inside of the hollow fiber membrane becomes.

SUMMARY

The present applications provides a medical instrument in which a length of each of the first hollow fiber membrane and second hollow fiber membrane from one partition to the other partition does not exceed a certain length.

A medical instrument includes at least one first hollow fiber membrane layer comprised of a plurality of integrated first hollow fiber membranes, and configured as a cylindrically-shaped body, and at least one second hollow fiber membrane layer disposed at the outer circumferential side of the first hollow fiber membrane layer concentric with the first hollow fiber membrane layer, the second hollow fiber membrane having a plurality of integrated second hollow fiber membranes, and configured as a cylindrically-shaped body, in which each of the first hollow fiber membranes and the second hollow fiber membranes is wound around the central axis of the cylindrical body, and a total number of times the second hollow fiber membranes are wound is smaller than a total number of times the first hollow fiber membranes are wound.

The medical instrument can be configured so that each of the first hollow fiber membranes passes through an outward path heading for the other end from one end of the cylindrical body and a homeward path heading for one end from the other end, is wound at least once around the central axis in the outward path, and is wound at least once around the central axis in the homeward path.

The medical instrument can also be configured so that each of the first hollow fiber membranes sequentially passes through a starting point which is set at one site of one end of the cylindrical body, a midpoint which is set at one site of the other end of the cylindrical body such that the midpoint is placed in the almost same position as the starting point in the circumferential direction of the cylindrical body, and an endpoint which is set at one site which is in the same position as the starting point or is in a position deviating from the starting point around the central axis, is wound at least once along the circumferential direction of the cylindrical body in the outward path heading for the midpoint from the starting point, and is wound at least once along the circumferential direction of the cylindrical body in the same direction as in the case of the outward path in the homeward path heading for the endpoint from the midpoint.

In each of the first hollow fiber membranes, a series of pathways having the outward path and the homeward path are repeated plural times.

(According to one embodiment, each of the second hollow fiber membranes passes through the outward path heading for the other end from one end of the cylindrical body and the homeward path heading for one end from the other end, and is wound once around the central axis while passing through the outward path and the homeward path.

According to another embodiment, each of the second hollow fiber membranes sequentially passes through a starting point which is set at one site of one end of the cylindrical body, a midpoint which is set at one site of the other end of the cylindrical body such that the midpoint is located in a position opposite to the starting point across the central axis of the cylindrical body, and an endpoint which is set at one site which is in the same position as the starting point or is in a position deviating from the starting point around the central axis, reaches the midpoint from the starting point at the shortest distance while being wound along the circumferential direction of the cylindrical body in the outward path heading for the midpoint from the starting point, and reaches the endpoint from the midpoint at the shortest distance while being wound along the circumferential direction of the cylindrical body in the same direction as in the case of the outward path in the homeward path heading for the endpoint from the midpoint.

With the second hollow fiber membrane configured as described above, in each of the second hollow fiber membranes, a series of pathways having the outward path and the homeward path are repeated plural times.

The inner diameter of the first hollow fiber membranes can be the same as the inner diameter of the second hollow fiber membranes.

The outer diameter of the first hollow fiber membranes can be the same as the outer diameter of the second hollow fiber membranes.

It is possible to configure the gap between the first hollow fiber membranes adjacent to each other to be the same as the gap between the second hollow fiber membranes adjacent to each other.

Moreover, the materials constituting the first hollow fiber membranes can be the same as materials constituting the second hollow fiber membranes.

The length of the first hollow fiber membrane layer extending along the central axis direction is preferably the same as a length of the second hollow fiber membrane layer extending along the central axis direction.

The medical instrument can be configured to include a plurality of the first hollow fiber membrane layers and a plurality of the second hollow fiber membrane layers, in which a first laminate is constituted with the plurality of the first hollow fiber membrane layers, and a second laminate is constituted with the plurality of the second hollow fiber membrane layers.

Each of the first hollow membrane layer and the second hollow membrane layer has either a function of performing gas exchange or a function of performing heat exchange.

The medical instrument is preferably an Oxygenator.

The number of times the second hollow fiber membranes, which constitute the second hollow fiber membrane layer positioned at the outer side, that is, the second hollow fiber membrane layer having a larger diameter between the first hollow fiber membrane layer and the second hollow fiber membrane layer, are wound is smaller than the number of times the first hollow fiber membranes, which constitute the first hollow fiber membrane layer having a smaller diameter, are wound. Consequentially, increase in the length of the second hollow fiber membranes from one partition to the other partition is prevented. As a result, it is possible to inhibit pressure loss from occurring in the second hollow fiber membranes when fluid passes through the inside of the second hollow fiber membranes.

Moreover, in the first hollow fiber membrane layer positioned in the inner side, the length of the first hollow fiber membranes from one partition to the other partition is controlled to be within a prescribed length. Accordingly, it is possible to inhibit pressure loss from occurring in the first hollow fiber membranes when fluid passes through the inside of the first hollow fiber membranes.

A production method of a medical instrument is disclosed where the medical instrument includes a first hollow fiber membrane layer comprised of a plurality of integrated first hollow fiber membranes, and a second hollow fiber membrane layer comprised of a plurality of integrated second hollow fiber membranes. The production method comprises configuring the first hollow fiber membrane layer as a cylindrically-shaped body by helically winding each of the first hollow fiber membranes around a central circumferential axis, wherein each helical winding of the first hollow fiber membrane layer traverses a central axis extending along an axial direction of the cylindrically-shaped body a first set number of times, and helically winding each of the second hollow fiber membranes to encircle the first hollow fiber membrane layer, wherein each helical winding of the second hollow fiber membrane layer traverses a central axis a second set number of times different that the first set of number of times.

DETAILED DESCRIPTION

Hereinafter, the medical instrument will be described in detail, based on preferable embodiments shown in attached drawings.

The left side inFIGS. 1, 3, 4, and 7 to 9will be described as “left” or “left-hand side”, and the right side in the drawings will be described as “right” or “right-hand side”. Furthermore, inFIG. 1toFIG. 7, the inside of the Oxygenator will be described as “blood inlet side” or “upstream side”, and the outside of the Oxygenator will be described as “blood outlet side” or “downstream side”.

An Oxygenator10shown inFIG. 1toFIG. 5has a columnar shape. The Oxygenator10is an Oxygenator equipped with a heat exchanger that includes a heat exchange portion10B disposed in the inside and performs heat exchange with blood, and an Oxygenator portion10A disposed at the outer circumferential side of the heat exchange portion10B and performs gas exchange with blood. The Oxygenator10is installed in an extracorporeal blood circulation circuit.

The Oxygenator10has a housing2A, and the Oxygenator portion10A and the heat exchange portion10B are housed in the housing2A.

The housing2A is constituted with a cylindrical housing main body21A, a dish-shaped first cap (left-side cap)22A that seals a left-end opening of the cylindrical housing main body21A, and a dish-shaped second cap (right-side cap)23A that seals a right-end opening of the cylindrical housing main body21A.

The cylindrical housing main body21A, the first cap22A, and the second cap23A are constituted with a resin material. The first cap22A and the second cap23A are fixed to the cylindrical housing main body21A, by a method such as fusion or bonding utilizing an adhesive.

In the outer circumferential portion of the cylindrical housing main body21A, a tubular blood outlet port28is formed. The blood outlet port28protrudes in a direction approximately tangential to the outer circumferential surface of the cylindrical housing main body21A (seeFIG. 5).

A tubular blood inlet port201and a gas outlet port27protrude from the first cap22A. The blood inlet port201is formed in the end surface of the first cap22A such that the central axis of the blood inlet port201becomes eccentric with respect to the center of the first cap22A. The gas outlet port27is formed in the outer circumferential portion of the first cap22A such that the central axis of the gas outlet port crosses (i.e., is coaxial with) the center of the first cap22A (seeFIG. 2).

In the second cap23A, a tubular gas inlet port26, a heat medium inlet port202, and a heat medium outlet port203are formed in a state of protruding from the second cap23A. The gas inlet port26is formed at the edge of the end surface of the second cap23A. The heat medium inlet port202and the heat medium outlet port203are respectively formed in a portion approximately corresponding to the central portion of the end surface of the second cap23A. Moreover, each of the centerline of the heat medium inlet port202and the centerline of the heat medium outlet port203is slightly oblique to the centerline of the second cap23A.

Note that, the housing2A does not need to form a shape of a complete cylinder as a whole. For example, the housing2A may form a partially defective shape or form a shape to which a portion having different shape has been added.

As shown inFIG. 3andFIG. 5, the Oxygenator portion10A, having a cylindrical shape along the inner circumferential surface of the housing2A, is housed in the housing2A. The Oxygenator portion10A is constituted with a first laminate30A that has a cylindrical body as a whole, a second laminate30A′ that forms a shape of a cylindrical body as a whole, and a filter member41A as air bubble-removing means4A.

As shown inFIG. 7, at the outer circumferential side (blood outlet portion side) of the first laminate30A (first hollow fiber membrane layer3A), the second laminate30A′ is disposed in a state of being concentric with the first laminate30A. That is, the second laminate30A′ surrounds or encircles the first laminate30A. Moreover, at the outer circumferential side of the second laminate30A′, the filter member41A is disposed.

The first laminate30A includes a plurality of first hollow fiber membrane layers3A. In addition, the second laminate30A′ includes a plurality of second hollow fiber membrane layers3A′.

As shown inFIG. 6, each first hollow fiber membrane layer3A is constituted with a plurality of first hollow fiber membranes31having a gas exchange function. In each first hollow fiber membrane layer3A, these first hollow fiber membranes31are integrated. In the first laminate30A, the plurality of first hollow fiber membrane layers3A, which are constituted with the plurality of first hollow fiber membranes31having a gas exchange function, are laminated on one another. Accordingly, gas exchange can be performed in the first laminate30A.

Furthermore, each second hollow fiber membrane layer3A′ is constituted with a plurality of second hollow fiber membranes31′ having a gas exchange function. In each second hollow fiber membrane layer3A′, these second hollow fiber membranes31′ are integrated. In the second laminate30A′, the plurality of second hollow fiber membrane layers3A′, which are constituted with the plurality of second hollow fiber membranes31′ having a gas exchange function, are laminated on one another. Accordingly, gas exchange can be performed in the second laminate30A′.

In the Oxygenator portion10A, the hollow fiber membrane layers for gas exchange are constituted with the first laminate30A and the second laminate30A′. A total number of the layers laminated on one another is not particularly limited, and is preferably, for example, 3 to 40.

Moreover, a length L1of the first hollow fiber membrane layers3A (first laminate30A) extending along the central axis is the same as a length L2of the second hollow fiber membrane layers3A′ (second laminate30A′) extending along the central axis. For example, L1and L2are preferably 30 mm to 250 mm, and more preferably 50 mm to 200 mm (seeFIG. 8). The first hollow fiber membrane layer3A and the second hollow fiber membrane layer3A′ satisfying the aforementioned conditions exhibit an excellent gas exchange function.

The first hollow fiber membranes31constituting the first hollow fiber membrane layer3A and the second hollow fiber membranes31′ constituting the second hollow fiber membrane layer3A′ are the same as each other in terms of the size and constituting materials, except for the way they are wound. Therefore, the first hollow fiber membranes31will be described representatively. Note that, the way the first hollow fiber membranes31are wound and the way the second hollow fiber membranes31′ are wound will be described later.

An inner diameter φd1of each of the first hollow fiber membranes31is preferably 50 μm to 700 μm, and more preferably 70 μm to 600 μm (seeFIG. 10). An outer diameter φd2of each of the first hollow fiber membranes31is preferably 100 μm to 900 μm, and more preferably 120 μm to 800 μm (seeFIG. 10). Moreover, a ratio d1/d2between the inner diameter φd1and the outer diameter φd2is preferably 0.5 to 0.9, and more preferably 0.6 to 0.8. In each of the first hollow fiber membranes31satisfying such conditions, strength of the membranes can be maintained, and at the same time, a degree of pressure loss occurring when gas is caused to flow in the lumen (flow path32) of the first hollow fiber membrane31can be suppressed to a relatively low level. For example, if the inner diameter φd1is larger than the aforementioned upper limit, the thickness of the first hollow fiber membrane31is reduced, and depending on other conditions, the strength of the membrane is reduced. Furthermore, if the inner diameter φd1is smaller than the aforementioned lower limit, depending on other conditions, a degree of pressure loss occurring when gas flows in the lumen of the first hollow fiber membrane31becomes relatively high.

In addition, a gap g between the first hollow fiber membranes31adjacent to each other is preferably 1/10 to 1/1 of the outer diameter φd2(seeFIG. 10). If the gap g is within the above range, as shown inFIG. 6, a blood flow path33, which makes it possible for blood to easily flow down toward the lower side from the upper side in the drawing, can be reliably formed in a void between the first hollow fiber membranes31.

A method for producing such a first hollow fiber membrane31is not particularly limited. For example, by using a drawing process, a solid-liquid phase separation process, or the like and by appropriately regulating conditions such as a spinning speed and the amount of resin to be ejected, the first hollow fiber membrane31having prescribed inner diameter φd1and outer diameter φd2can be produced.

As a material constituting each of the first hollow fiber membranes31, polypropylene is preferable. Moreover, it is more preferable for the first hollow fiber membrane31to have micropores formed in the wall portion by a drawing process or a solid-liquid phase separation process. That is, it is more preferable for the first hollow fiber membrane31to be constituted with porous polypropylene. If the first hollow fiber membrane31is formed of such a material, gas exchange between blood and the first hollow fiber membrane31reliably occurs.

As shown inFIG. 3, both ends of the first laminate30A or both ends of the second laminate30A′, that is, a left end (one end) and a right end (the other end) of the first laminate30A and the second laminate30A′ are respectively fixed to the inner surface of the cylindrical housing main body21A by partitions8and9. As a result, both ends of each of the first hollow fiber membranes31are in a state of being fixed to the cylindrical housing main body21A. The partitions8and9are constituted with, for example, a potting material such as polyurethane or silicone rubber or an adhesive.

Moreover, a space between the cylindrical housing main body21A and the heat exchange portion10B is filled with the first laminate30A and the second laminate30A′. Accordingly, each of the laminates forms approximately a cylindrical shape as a whole. Consequentially, for the cylindrical housing main body21A having the similar shape, a high packing efficiency resulting from the first laminate30A and the second laminate30A′ is obtained (a dead space is reduced), and this makes a contribution to miniaturization and improvement of performance of the Oxygenator portion10A.

A blood inlet space24A that is in communication with the blood inlet port201is formed at the upstream side of the blood flow path33(i.e., at the upstream side from the heat exchange portion10B positioned at the inner circumferential side of the Oxygenator portion10A). The blood inlet space24A is a blood inlet portion for the blood flowing in from the blood inlet portion201. (seeFIG. 3andFIG. 5).

The blood inlet side space24A is a space constituted with a first cylinder member241that forms a cylindrical shape and a plate piece242that is disposed inside the first cylinder member241while facing a portion of the inner circumferential portion of the first cylinder member241. The blood flowing into the blood inlet side space24A can flow down toward the entire blood flow path33through a plurality of side holes243formed in the first cylinder member241.

At the downstream side of the blood flow path33, a cylindrical void is formed between the outer circumferential surface of the filter member41A and the inner circumferential surface of the cylindrical housing main body21A. The void forms a blood outlet side space25A. The blood outlet side space25A and the blood outlet port28which is in communication with the blood outlet side space25A constitute a blood outlet portion. The blood outlet portion has the blood outlet side space25A. Accordingly, a space that allows the blood having passed through the filter member41A to flow toward the blood outlet port28is secured, whereby the blood can be smoothly discharged.

Moreover, between the blood inlet side space24A and the blood outlet side space25A, the first hollow fiber membrane layer3A, the filter member41A, and the blood flow path33are provided.

Furthermore, at the downstream side (blood outlet portion side) of the second hollow fiber membrane layer3A′, the air bubble-removing means4A, which captures air bubbles in the blood and removes the air bubbles from the blood, is disposed. The air bubble-removing means4A has the filter member41A.

The filter member41A captures air bubbles present in the blood flowing in the blood flow path33.

The filter member41A is a sheet-like member (hereinafter, also simply referred to as “sheet”) that forms approximately a rectangular shape. The filter member41A is formed of the sheet wound up in the form of cylinder. Both ends of the filter member41A are fixed by the partitions8and9respectively, and as a result, the filter member41A is fixed to the housing2A (seeFIG. 3).

The filter member41A is disposed such that its inner circumferential surface comes into contact with the surface of the downstream side (blood outlet portion side) of the second hollow fiber membrane layer3A′. The filter member41A covers approximately the entire surface of the downstream side of the second hollow fiber membrane layer3A′. If the filter member41A is disposed as above, an effective area of the filter member41A can be increased, and the ability to capture air bubbles can be sufficiently demonstrated. Moreover, if the effective area of the filter member41A is increased, even when the filter member41A is partially clogged (for example, even when blood clots and the like adhere to the filter member41A), it is possible to prevent overall blood flow from being impeded.

As shown inFIG. 3, at the inside of the first cap22A, a rib291forming an annular shape protrudes from the inside of the first cap22A. Moreover, a first chamber221ais constituted with the first cap22A, the rib291, and the partition8. The first chamber221ais a gas outlet chamber from which gas flows out. The left-end opening of each of the first hollow fiber membranes31and the second hollow fiber membranes31′ is opened to and is in communication with the first chamber221a.

Meanwhile, at the inside of the second cap23A, a rib292forming an annular shape protrudes from the inside of the second cap23A. Moreover, the second cap23A, the rib292, and the partition9constitute a second chamber231a. The second chamber231ais a gas inlet chamber into which gas flows. The right-end opening of each of the first hollow fiber membranes31and the second hollow fiber membranes31′ is opened to and is in communication with the second chamber231a.

The lumen of each of the first hollow fiber membranes31and the lumen of each of the second hollow fiber membranes31′ constitute the flow path32which is a gas flow path. The gas inlet port26and the second chamber231aconstitute the gas inlet portion positioned at the upstream side of the flow path32. Moreover, the gas outlet port27and the first chamber221aconstitute the gas outlet portion positioned at the downstream side of the flow path32.

The heat exchange portion10B is disposed inside the Oxygenator portion10A. Similarly to the Oxygenator portion10A, the heat exchange portion10B has the first laminate30A which is constituted with the first hollow fiber membrane layers3A and a second laminate30A′ which is disposed at the outer circumferential side of the first laminate30A and constituted with the second hollow fiber membrane layers3A′. The first laminate30A and the second laminate30A′ in the heat exchange portion10B are the same as the first laminate30A and the second laminate30A′ in the Oxygenator portion10A respectively, except that the first laminate30A and the second laminate30A′ in the heat exchange portion10B perform heat exchange. That is, similarly to the first hollow fiber membrane layers3A of the Oxygenator portion10A, the first laminate30A and the second laminate30A′, which perform heat exchange in the heat exchange portion10B, are constituted with a plurality of the first hollow fiber membranes31or the second hollow fiber membranes31′. Furthermore, in the first laminate30A, the first hollow fiber membranes31are integrated, and a void (space) between the first hollow fiber membranes31becomes the blood flow path33. In addition, in the second laminate30A′, the second hollow fiber membranes31′ are integrated, and a void (space) between the second hollow fiber membranes31′ becomes the blood flow path33.

In the heat exchange portion10B, the first laminate30A and the second laminate30A′ constituting the heat exchange portion10B constitute the hollow fiber membrane layers for heat exchange.

Herein, regarding the first laminate30A and the second laminate30A′ in the heat exchange portion10B, differences between these laminates and the first laminate30A and the second laminate30A′ in the aforementioned Oxygenator portion10A will be mainly described.

As shown inFIG. 3, in the heat exchange portion10B, each of the two ends of the first laminate30A and each of the two ends of the second laminate30A′ (that is, the left end (one end) and the right end (the other end) of each of the first laminate30A and the second laminate30A′) are respectively fixed to the inner surface of the cylindrical housing main body21A by the partitions8and9. Moreover, the inner circumferential portion of the first laminate30A engages a concave-convex portion244formed in the outer circumferential portion of the first cylinder member241. By being engaged in this manner and being fixed by the partitions8and9, the first laminate30A is fixed to the cylindrical housing main body21A. As a result, it is possible to prevent or inhibit occurrence of positional shift of the first laminate30A when the Oxygenator10is being used.

At the inside of the first cylinder member241, a second cylinder member245is disposed concentrically with the first cylinder member241. Moreover, as shown inFIG. 3, a heat medium (for example, water) having flowed in from the heat medium inlet port202sequentially passes through the flow path32(heat medium flow path) of each of the first hollow fiber membranes31of the first hollow fiber membrane layer3A positioned at the outer circumferential side of the first cylinder member241or the flow path32(heat medium flow path) of each of the second hollow fiber membranes31′ of the second hollow fiber membrane layer3A′ and the inside of the second cylinder member245, and is then discharged out of the heat medium outlet port203. Furthermore, when the heat medium passes through the flow path32, heat exchange (heating or cooling) is performed between the blood, which comes into contact with the hollow fiber membrane forming the flow path32, and the heat medium.

If the heat exchange portion10B is disposed inside the Oxygenator portion10A as described above, the following effects are exerted. That is, first, the Oxygenator portion10A and the heat exchange portion10B can be efficiently housed in a single housing2A, and a dead space is reduced. Accordingly, gas exchange can be efficiently performed in the small Oxygenator10. Second, the Oxygenator portion10A and the heat exchange portion10B are disposed close to each other. Accordingly, it is possible to allow the blood having undergone heat exchange in the heat exchange portion10B to flow into the Oxygenator portion10A while preventing the blood from releasing or absorbing heat as far as possible.

As materials constituting the first hollow fiber membranes31that constitute the heat exchange portion10B, it is possible to use, for example, polyethylene terephthalate, polycarbonate, polyurethane, nylon, polystyrene, and vinyl chloride, in addition to those exemplified as the materials constituting the first hollow fiber membranes31that constitute the aforementioned Oxygenator portion10A.

Next, blood flow in the Oxygenator10of the present embodiment will be described.

In the Oxygenator10, the blood having flowed in from the blood inlet port201sequentially passes through the blood inlet side space24A and the side holes243, and flows into the heat exchange portion10B. In the heat exchange portion10B, the blood keeps flowing in the blood flow path33toward the downstream side, and in this state, the blood undergoes heat exchange (heating or cooling) by coming into contact with the surface of each of the first hollow fiber membranes31or the surface of each of the second hollow fiber membranes31′. The blood having undergone heat exchange in this manner flows into the Oxygenator portion10A.

Thereafter, in the Oxygenator portion10A, the blood flows in the blood flow path33toward the downstream side. Meanwhile, the gas (oxygen-containing gas) having been supplied from the gas inlet port26is distributed to each flow path32of each of the first hollow fiber membranes31and second hollow fiber membranes31′ from the second chamber231a. After flowing in the flow path32, the gas is introduced in the first chamber221aand discharged out of the gas outlet port27. The blood flowing in the blood flow path33comes into contact with the surface of each of the first hollow fiber membranes31or with the surface of each of the second hollow fiber membranes31′, whereby gas exchange (addition of oxygen or removal of carbon dioxide) is performed between the blood and the gas flowing in the flow path32.

When there are air bubbles in the blood having undergone gas exchange, these air bubbles are captured by the filter member41A. As a result, the air bubbles are prevented from flowing out toward the downstream side of the filter member41A.

The blood, which has undergone gas exchange and removal of air bubbles as described above, flows out of the blood outlet port28.

As described above, the first hollow fiber membranes31constituting the first hollow fiber membrane layer3A differ from the second hollow fiber membranes31′ constituting the second hollow fiber membrane layer3A′, in terms of the way they are wound (seeFIG. 8andFIG. 9). Hereinafter, the way they are wound will be described. Note that, inFIG. 8(a)andFIG. 9(a), one out of the plurality of first hollow fiber membranes31, which constitute the first hollow fiber membrane layer3A positioned at the outermost side of the first laminate30A, is described representatively. Furthermore, inFIG. 8(b)andFIG. 9(b), one out of the plurality of second hollow fiber membranes31′, which constitute the second hollow fiber membrane layer3A′ positioned at the outermost side of the second laminate30A′, is described representatively.

As shown inFIG. 8(a)andFIG. 9(a), the first hollow fiber membrane layer3A forms a cylindrical body. Moreover, the first hollow fiber membrane31is helically wound around a central axis300of the cylindrical body, in the direction indicated by the arrow inFIG. 8(a)andFIG. 9(a). The first hollow fiber membrane31sequentially passes through three points set on the outer circumference of the cylindrical body.

A first point (starting point)301is set at one site of the left-end side (one end) of the cylindrical body.

A second point (midpoint)302is set at one site of the right-end side (the other end) of the cylindrical body, such that the second point302is located in almost the same position as the first point301in the circumferential direction of the cylindrical body. Accordingly, provided that a line orthogonal to the central portion of the central axis300in the longitudinal direction is taken as a line of symmetry, the first point301and the second point302have a positional relationship in which they are symmetrical to each other relative to the line of symmetry.

A third point (endpoint)303is set at a site which is almost the same as the first point301. Note that, the third point303may be set at one site which deviates from the first point301by a predetermined angle (for example, 0.5° to 15°) around the central axis300. Herein, “almost” means that the third point303is not overlapped with the first point301and is in a position adjacent to the first point301.

As shown inFIG. 8(a), in the outward path heading for the second point302(the other end) from the first point301(one end), the first hollow fiber membrane31is wound once along the circumferential direction of the cylindrical body (FIG. 9(a)shows the same constitution). The first hollow fiber membrane31is then folded in the second point302. In the homeward path heading for the third point303(one end) from the second point302(the other end), the first hollow fiber membrane31is wound once along the same direction as the circumferential direction of the cylindrical body, as the first hollow fiber membrane31is wound in the outward path. In this way of winding, the first hollow fiber membrane31is wound twice (around the central axis300) along the circumferential direction of the cylindrical body while it is passing through the outward path and homeward path. Moreover, in the first hollow fiber membrane31, the middle of a portion311of the outward path and the middle of a portion312of the homeward path cross each other at one site (seeFIG. 9(a)).

Note that, in the Oxygenator10, it is preferable to provide a first engagement portion, which makes the first hollow fiber membrane31folded by being engaged with this portion, to the second point302.

As shown inFIG. 8(b)andFIG. 9(b), the second hollow fiber membrane layer3A′ forms a shape of a cylindrical body (cylindrical shape). Moreover, the second hollow fiber membrane31′ is helically wound around a central axis300′ of the cylindrical body, in the direction indicated by the arrow inFIG. 8(b)andFIG. 9(b). The second hollow fiber membrane31′ sequentially passes through three points set on the outer circumference of the cylindrical body.

A first point (starting point)301′ is set at one site of the left-end side (one end) of the cylindrical body.

A second point (midpoint)302′ is set at one site of the right-end side (the other end) of the cylindrical body, such that the second point302′ is located in a position almost opposite to the first point301′ across the central axis300′. Accordingly, provided that the central portion of the central axis300′ in the longitudinal direction is taken as a center of symmetry, the first point301′ and the second point302′ have a positional relationship in which they are practically symmetrical to each other around the center.

A third point (endpoint)303′ is set at a site which is almost the same as the first point301′. Note that, the third point303′ may be set at one site which deviates from the first point301′ by a predetermined angle around the central axis300′. Herein, “almost” means that the third point303′ is not overlapped with the first point301′ and is in a position adjacent to the first point301′.

As shown inFIG. 8(b), in the outward path heading for the second point302′ (the other end) from the first point301′ (one end), the second hollow fiber membrane31′ is wound along the circumferential direction of the cylindrical body by 0.5-circumference (semi-circumference), and reaches the second point302′ from the first point301′ at the shortest distance (FIG. 9(b)shows the same constitution). Moreover, the second hollow fiber membrane31′ is folded at the second point302′. In the homeward path heading for the third point303′ (the other end) from the second point302′ (one end), the second hollow fiber membrane31′ is also wound along the circumferential direction of the cylindrical body in the same direction as in the case of the outward path by 0.5-circumference (semi-circumference), and reaches the third point303′ from the second point302′ at the shortest distance. In this way of winding, the second hollow fiber membrane31′ is wound once (around the central axis300′) along the circumferential direction of the cylindrical body while it is passing through the outward path and homeward path.

Note that, in the Oxygenator10, it is preferable to provide a second engagement portion, which makes the second hollow fiber membrane31′ folded by being engaged with this portion, to the second point302′.

As described above, in the Oxygenator10, while passing through the outward path and the homeward path, the first hollow fiber membrane31is wound twice along the circumferential direction of the cylindrical body. Moreover, while passing through the outward path and the homeward path, the second hollow fiber membrane31′ is wound once along the circumferential direction of the cylindrical body. That is, in the Oxygenator10, the total number of times the second hollow fiber membrane31′ is wound is smaller than the total number of times the first hollow fiber membrane31is wound.

Oxygenators of the related art include an Oxygenator which has hollow fiber membrane layers consisting of a plurality of hollow fiber membranes laminated on one another and forming a shape of a cylindrical body as a whole. In each of the layers, the hollow fiber membranes travels between one end and the other end of the cylindrical body while being helically wound one by one around the central axis of the cylindrical body. Moreover, in this Oxygenator, each of the hollow fiber membranes is wound at least once around the central axis of the cylindrical body, in an outward path heading for the other end from one end of the cylindrical body. In a homeward path heading for one end from the other end, each of the hollow fiber membranes is also wound at least once around the central axis of the cylindrical body. In each of the hollow fiber membranes wound as above, a length of the layer wound once around the central axis of the cylindrical body increases toward the outer circumference of the cylindrical hollow fiber membrane layer. As a result, a length of some of the membranes from one partition to the other partition exceeds a prescribed length (certain length). In this case, in the hollow fiber membranes having a length exceeding a prescribed length, pressure loss of the gas passing through these hollow fiber membranes becomes greater than in hollow fiber membranes having a length that is within a prescribed length.

However, in the Oxygenator10disclosed here, the total number of times the second hollow fiber membranes31′, which constitute the second hollow fiber membrane layer3A′ positioned at the outer side (that is, the second hollow fiber membrane layer3A′ having a larger diameter between the first hollow fiber membrane layer3A and the second hollow fiber membrane layer3A′) are wound is smaller than the total number of times the first hollow fiber membranes31, which constitute the first hollow fiber membrane layer3A having a smaller diameter, are wound. Accordingly, since the number of times the second hollow fiber membranes31′ are wound is reduced, the length of the second hollow fiber membranes31′ from one partition to the other partition is prevented from exceeding the prescribed length. Consequentially, it is possible to inhibit pressure loss from occurring in the second hollow fiber membranes31′ when gas passes through the inside of the second hollow fiber membranes31′.

Moreover, in the first hollow fiber membrane layer3A positioned at the inner side, the length of the first hollow fiber membranes31is controlled to be within a prescribed length. Consequentially, it is possible to inhibit pressure loss from occurring in the first hollow fiber membranes31when gas passes through the first hollow fiber membranes31.

Moreover, in the heat exchange portion10B, a length of the second hollow fiber membrane31′ of the second hollow fiber membrane layer3A′ from one partition to the other partition is prevented from exceeding a prescribed length. Consequentially, it is possible to inhibit pressure loss from occurring when a heat medium passes through the inside of the second hollow fiber membrane31′. As a result, heat exchange can be easily and reliably performed through the second hollow fiber membrane31′.

In order to produce the first hollow fiber membrane layer3A by helically winding the first hollow fiber membranes31or to produce the second hollow fiber membrane layer3A′ by helically winding the second hollow fiber membranes31′, for example, a system including a rotary apparatus that rotates a cylindrical core, around which the hollow fiber membranes are wound, and a winder apparatus is used. At least one of the rotary apparatus and the winder apparatus moves in the axial direction of the core. Moreover, the rotary apparatus and the winder apparatus are moved relative to the axial direction of the core. In this state, the hollow fiber membranes are wound off from the winder apparatus, and the core is rotated by the rotary apparatus. In this manner, the hollow fiber membranes are helically wound around the core. Note that, the hollow fiber membranes may be wound around the core one by one, or alternatively, a plurality of the membranes may be simultaneously wound around the core.

Up to now, the medical instrument has been described in regard to the embodiments shown in the drawings, but the medical instrument disclosed here is not limited in this way. Each portion constituting the medical instrument can be replaced with a portion having any constitution that can perform the same function. Moreover, any constituent may be added to the medical instrument.

In addition, in the aforementioned embodiments, each of the first hollow fiber membrane layer and the second hollow fiber membrane layer is in the form of a laminated layer in the Oxygenator. However, the present application is not limited in this way, and for example, at least one of the first hollow fiber membrane layer and the second hollow fiber membrane layer may be a single layer.

Moreover, in the aforementioned embodiments, each of the hollow fiber membranes constituting each of the hollow fiber membrane layers of the Oxygenator portion is the same as each of the hollow fiber membranes constituting each of the hollow fiber membrane layers of the heat exchange portion. However, the hollow fiber membranes are not limited to this configuration, and for example, one (the former) hollow fiber membrane may be finer than the other (the later) hollow fiber membrane, or alternatively, both the hollow fiber membranes may be constituted with different materials.

Furthermore, inside the heat exchange portion, a hollow fiber membrane layer having the same function as each of the hollow fiber membrane layers of the Oxygenator portion, that is, a hollow fiber membrane layer having a gas exchange function may be disposed.

In addition, in the aforementioned embodiments, the heat exchange portion includes hollow fiber membrane layers having a heat exchange function. However, the heat exchange portion may include a so-called bellows-type heat exchanger. The exchanger can be constituted with metal materials such as stainless steel and aluminum or resin materials such as polyethylene, polyethylene terephthalate, polycarbonate, polyurethane, and nylon.

Moreover, in the aforementioned embodiments, in each of the outward path heading for the second point from the first point and the homeward path heading for the third point from the second point, the first hollow fiber membrane is wound once along the circumferential direction of the cylindrical body. However, the medical instrument disclosed here is not so limited, and the first hollow fiber membrane may be wound twice or more times.

Furthermore, in each of one first hollow fiber membrane and one second hollow fiber membrane, a series of pathways having an outward path and a homeward path may be repeated plural times. If the pathways are repeated plural times, each of the first hollow fiber membranes or each of the second hollow fiber membranes can be continuously wound, and accordingly, the production efficiency of the first hollow fiber membrane layer or the second hollow fiber membrane layer is improved.

The medical instrument includes at least one first hollow fiber membrane layer which has a plurality of first hollow fiber membranes, obtained by integrating the plurality of first hollow fiber membranes, and forms a shape of a cylindrical body as a whole, and at least one second hollow fiber membrane layer which is disposed at the outer circumferential side of the first hollow fiber membrane layer in a state of being concentric with the first hollow fiber membrane layer, has a plurality of second hollow fiber membranes, is obtained by integrating the plurality of second hollow fiber membranes, and forms a shape of a cylindrical body as a whole, in which each of the first hollow fiber membranes and the second hollow fiber membranes is wound around the central axis of the cylindrical body, and a number of times the second hollow fiber membranes are wound is smaller than a number of times the first hollow fiber membranes are wound. Accordingly, each of the first hollow fiber membranes and the second hollow fiber membranes is prevented from exceeding a certain length.

The detailed description above describes embodiments of a medical instrument and a method for producing a medical instrument representing examples of the medical instrument and method of the present invention. The invention is not limited, however, to the precise embodiments and variations described. Various changes, modifications and equivalents can be effected by one skilled in the art without departing from the spirit and scope of the invention as defined in the accompanying claims. It is expressly intended that all such changes, modifications and equivalents which fall within the scope of the claims are embraced by the claims.