DD141456A5 - METHOD AND DEVICE FOR BLOOD DIFFUSION - Google Patents

Description

The invention relates to a membrane diffusion device for blood diffusion systems.

Membrane oxygenators are currently being widely used in so-called heart / lung machines to maintain the patient's respiratory and circulatory systems in open-heart surgery and the like.

It is also known to provide a built-in heat exchanger for blood oxygenators to allow convenient oxygenated blood temperature control (see, for example, U.S. Patent No. 3,998,593).

For blood diffusion systems, such as oxygenators, the pressure drop in the blood flow path should preferably be as small as possible from the beginning to the end of the system. In addition, the mixing and flow characteristics of the blood should be as good as possible to ensure optimal oxygenation.

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oxygenation and heat exchange properties.

In particular, in membrane oxygenation, it is also highly desirable to provide a highly effective means for separating gas bubbles from the blood prior to its return to the patient. Gas bubbles may appear in the blood as a result of detachment of air bubbles trapped in the bloodstream after prefilling the device; Similarly, gas bubbles may enter the blood flow line via the venous line during surgery, which can be quite common. Especially in the case of using porous, hydrophobic oxygenating membranes, a highly effective bladder separation function in the device ensures safe protection of the patient from blisters which penetrate through the pores of the oxygenation membrane due to an increase in pressure on the gas side of the membrane, although in such a plant there are others , commercially available safety devices may be provided.

Object of the invention:

The object of the invention is to provide an integrated or unitized diffusion system for blood, in particular an oxygenation system, which ensures a low pressure drop in connection with a highly effective oxygenation or oxygenation and a very efficient heat exchange as an indication of a good mixing of the blood , Advantageously, while the container of the device is a very effective bubble trap, which is able to separate large amounts of gas bubbles, which can exceed the capacity of other bubble traps previously used in the membrane oxygenation.

This object is achieved according to the invention in a membrane diffusion device for a blood diffusion system

first blood flow paths arranged in nested diffusion exchange relation to a plurality of second fluid flow paths on opposite sides of a semipermeable membrane and communicating with an inlet and an outlet, respectively, through an inlet and outlet heat exchanger and an outlet of the first flow paths connecting device to the inlet of the heat exchanger, by a rigid container with inlet and outlet and a device connecting the outlet of the heat exchanger with the container inlet for defining a Blutströmungskreislaufs by the membrane diffusion device, the heat exchanger and the container, and in that the blood circulation perpendicular to the Directions of blood flow from inlet (7 \ nfang) to the outlet (Ende.) Has a substantially constant width.

Thus, the blood flow circle has a substantially constant width perpendicular to the direction of blood flow from its beginning at the inlet in the membrane diffusion device through the container. In other words, there is no constriction of the blood flow path to a pipeline between the membrane diffusion device and the heat exchanger, any more than between the heat exchanger and the vessel. This training offers advantages in two cases:

First, the blood entering the heat exchanger with further flow distribution favors a uniform flow of blood through the individual flow paths of the heat exchanger, which in turn may be, for example, of the general type disclosed in US Pat. No. 3,640,340, in which the heat exchanger means is a tortuous metal heat exchange wall with the bi-flow circuit extending through a first set of pockets in one side of the heat exchange wall, while the heat exchange medium flows through the pockets interleaved therewith on the other side of the heat exchange wall.

Due to the uniform and wide flow distance of the blood over the entire width of the heat exchanger, the flow through the individual pockets or other blood flow paths of the heat exchanger can be made uniform. As a result, differences in the flow distribution in the blood flow paths of the heat exchanger can be avoided. This in turn ensures a reduced pressure drop in the heat exchanger in conjunction with a uniform blood flow.

Secondly, by the undiminished width of the blood flow from the heat exchanger to the container, a thin, turbulence-free blood ligament is effectively formed which preferably flows down a sloping bottom of the container to a type of blood storage column; the container outlet is located at the bottom of the column. The thin, broad band of blood flowing over the sloping container bottom provides enough opportunity for escape of bubbles contained within it, while the comparatively calm or stagnant column of blood with the bottom withdrawal opening provides another opportunity for bladder removal. In an emergency, in which a large proportion of bubbles enters the blood, the bubbles can thus be removed from the blood in the container, wherein the gases are discharged through venting elements from the container.

Thus, according to the present invention, there is provided a safe, effective diffusion system for blood, particularly an oxygenation system, which has a low pressure drop, allows for the use of a smaller number of lower power pumps, and subjects the blood cells to lower loads.

The invention also provides an improvement in the assembly of so-called zig-zag membrane oxygenators in which a one-piece spacer is provided at the respective opposite ends of the flow paths

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the. Membrane pockets is formed; eliminating the need for a sealing tape or other

moderately complex measures to seal the ends of the per se conventionally constructed Membranstapeis is avoided.

Due to the inventively provided, molded spacers, the folded membrane stack can be combined with the same or better reliability of the seal at the ends' economical.

The invention also provides a diffusion device for blood having a diffusion-transmitting semipermeable membrane folded into a stack in the form of a plurality of membrane layers having a blood flow over a plurality of first parallel flow paths and a flow of another fluid over a plurality of second parallel flow paths disposed between the first flow paths and separated by the membrane therefrom, and having a rigid, one-piece pad having transverse, substantially parallel fold or crease lines and folded in sections along these crease lines and in the second mentioned flow paths is disposed on one side of the membrane to support the membrane layers, and which is provided with spaced-apart openings to allow a fluid passage, which is characterized by vorg at both edges of the rigid pad itehene, laterally or transversely arranged tabs, which are folded inwards against the inner portions of the pad and bonded to form double dikker edge portions of the pad with this, so that they form at the opposite membrane edges spacers and sealing elements.

Preferably, the rigid, one-piece backing may be coated with a thin film of a thermoplastic material, such as polyethylene. At a convenient time during the folding process, the thermoplastic coating on the tabs is heated by, for example, hot air and thereby softened on the tabs at the edge of the base. The folded tabs can then be pressed against the other portions of the pad, so that the thermoplastic coating adheres the tabs flat with the rest of the pad.

Thus, when the pad is folded along the transverse score lines to form the said stack of membrane layers with the interposed pad portions, the double thickness possessing edges of the pad will form spacers and sealants along those edges.

The pad is preferably covered with spacers prior to folding at locations between the spaced apertures in the pad. Then, a diffusion membrane of such width and in such an arrangement is placed on the base and the spacers that it comes to rest over the spacers and the openings. Then pad, spacer and membrane can be merged into convoluted, folded sections, the folding being along the crease lines. In this way, a diffusion membrane stack is formed with interleaved pad and membrane pockets, the folded tabs serve as sealing elements with - compared to the rest of the stack ~ enlarged Dikke, so.dass when inserting the stack in a tight-fitting housing a seal to the opposite edges of the stack is produced.

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In the following a preferred embodiment of the invention is explained in more detail with reference to the accompanying drawings. Show it:

1 is a side view of a membrane diffusion device according to the invention for the oxygenation or oxygenation of blood,

2 is a side view of the device of FIG. 1, rotated by 90 ° about its vertical axis,

3 shows a longitudinal section through a flow envelope for illustrating a part of the oxygen and blood flow path in the interior of the membrane diffusion device according to FIG. 1, FIG.

4 is a plan view of the diaphragm pad and associated parts used to define the various flow pockets of the device of FIG. 1;

Fig. 5 is a perspective view of the apparatus of FIG. 1 and

6 is a partial section along the line 6-6 in Fig. 2nd

The diffusion system 10 shown in the figures comprises a membrane diffusion device 12 which may be constructed substantially in accordance with U.S. Patents 3,879,293 and 3,757,955.

The membrane diffusion device or the oxygenator 12 comprises a porous, hydrophobic membrane, such as polypropylene, which has tiny pores in the submicron range (size below 1 μπι), which allow gas easily pass through the membrane, but retain blood fluid.

The membrane 14 is collapsed in the manner described in said US-PSen to a plurality of (preferably about 75) separate Strönvungshüllen 16 or bags 16, wherein it is placed on a flat pad 18, preferably made of polyethylene or a similar thermoplastic material treated cardboard.

In the illustrated embodiment, a strip of mesh or screening material 20 (screening) is placed on the paperboard pad 18, whereupon the membrane 14 is placed on the pad and the latter along fold lines 24 according to said US patents in a series of panels 22 is folded into a series of (zigzag) convolutions to form the interconnected sheaths 16. In this case, the blood path runs between sections of the membrane 14 in each pocket 16 from one edge 31 to the other edge 33, while the oxygen flow path with interposed sieve material 20 lies between the base sections 22 and a membrane section 14.

In the bloodstream of the individual, interconnected pockets 16 more mesh or sieve material 26 can be used.

The pad 18 has longitudinal cutouts 28 in which portions of adjacent sheets 22 of Figures 20 to 22 of U.S. Patent 3,757,955 can cooperate to form contiguous manifold flow passages for controlling the flow of gaseous oxygen and blood into and out of each shell to favor.

At the edges of the pad 1.8 additional tabs 30 are provided, which are folded along folding lines 32 inside to the. Ends of each shell a seal

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manufacture. The paperboard material of the pad 18 may be coated with a polyethylene having a comparatively low melting point or the like, so that the tabs 30 may be welded by fusing this material and thus adhesively bonded and sealed in its folded-over position. The side edges of the pad 18 may be coated with a double-sided adhesive tape. The comparatively narrow screen material 26 is inserted between the edges provided with adhesive tape. Then the membrane 14 is placed with its edges adhering to the tape. The assembly is then folded harmonically along the score lines 24, whereby screen material 26 can be inserted into the interconnected envelopes or pockets 16 formed therewith. When folding the assembly, beads of an RTV sealant (RTV sealant) may be applied along the membrane edges to improve sealing.

The (thermal) welding can be done simply by blowing hot air against the flaps 30 and the edges of the pad 18 to melt the polyethylene coating. The folded Karton- pad 18 can be guided by the hot air jet, whereupon the folded tabs 30 are pressed down against the remaining portions of the pad 18 to stick together after cooling of the polyethylene.

The described method avoids the need for the use of adhesive tape or tapes to make the end spacers and seals of the molded envelopes or pockets; moreover, it replaces the generally manual operation with a method that is fully automated.

Alternatively, instead of the hot air, a Klebmittei be sprayed to glue in this way the tabs 30 with the main part of the pad 18.

In addition, by means of the hot air jet, the mesh or Siebmaterialstücke 26 are glued to the carton by the polyethylene in the central region of the cardboard panels or if desired, the Siebmaterialstücke be melted.

Referring to FIG. 4, the screen material 26 is preferably sized to lie between opposed, spaced, longitudinal cutouts or openings 28 at the two edges of the pad 18. As a result, closing the openings or cutouts 28 through the screen material 26 is prevented. Likewise, the tabs 30 are preferably sized so that they do not overlap the cutouts 28. On the other hand, the membrane 14, which is placed after the screen material 26 on the pad, according to FIG. 4 advantageously has a width which almost corresponds to that of the pad 18 after folding the tabs 3 0, thereby adhering the edges of the membrane 14 facilitate.

The inventive stacking arrangement of the semi-permeable membrane and the pads, through which the individual envelopes or pockets 16 are formed, can be assembled by a continuous, automated process, are used in the rolls of material of the pad 18, the screen material 16 and the membrane 14 and conventional transport rollers or the like are provided for the control of the feed of the arrangement.

The unitary stack with the interconnected sheaths or pockets 16 is inserted, substantially in accordance with US Pat. No. 3,879,293, into a canister 34 closed by a lid 36, which

is sized so that it presses firmly against the folded tabs 30 in the stack and seals against their ends.

A gas inlet 3 5 connectable to an oxygen supply serves to supply the gaseous oxygen via a gas inlet port 37 to allow the gas to flow through the envelope or pocket stack. The gas flowing out of the device via a gas outlet opening 39 is discharged from the device via a gas outlet (neck) 38.

A blood inlet 40 (Figure 2), in the form of a wide or wide opening, draws blood from a Utrecht-extending conduit 4 2 provided with means for connection to a flexible conduit via which venous blood is accepted by the patient. With the blood inlet 4 0 is a port 44 in communication, which may be connected during surgery with a Herzschnittabsauger.

The purpose of the vertically extending line 4 2 is to constantly maintain a certain stagnation or drop pressure in the oxygenator 12 in the case of line 4 2 filled with blood.

The blood flows through the wide inlet opening 40, which extends as shown in FIG. 2 substantially over the entire width of the oxygenator, in the latter, and then in the direction of arrows 46 in the interconnected sheaths or pockets 16 to flow and then in a wide distribution in the direction of arrows 48 to flow through the length of the cases or pockets. For discharging the blood at the other ends of the pockets 16, the blood flows out of the pockets in the direction of the arrows 50 to be withdrawn via the wide blood outlet 52, which communicates directly with a wide blood inlet 58 of a heat exchanger 54 ,

The blood flow path through the heat exchanger 54 has the same width as the flow path in the oxygenator 12, in a direction perpendicular to the directions 4 8 , 50 and 54, as shown specifically in FIG. This width corresponds to the width of the respective blood flow paths through the pockets 16, through the outlet slot 52 of the oxygenator and the inlet slot 58 of the heat exchanger.

However, the heat exchanger 54 preferably includes about 58 pockets or blood channels 59 in its convoluted or folded wall so as to have a significantly increased width and width compared to the known heat exchanger has a significantly reduced flow resistance. The blood channels 59 of the heat exchanger 54 are preferably free of flow distribution screens or other flow resistance increasing means so as to ensure more uniform flow in the various flow channels to the heat exchanger. This is because the large connection widths of the blood outlet 52 from the oxygenator 12 and the blood inlet 58 of the heat exchanger 54 substantially reduce uneven flow in the flow channels 59, so that such sieving becomes unnecessary for distribution.

The blood channels 59 in the heat exchanger may, for example, have a thickness of 1.6 mm, a depth of 12.7 mm and a length of 1.08 mm.

The blood flows from the channels 59 of the heat exchanger 54 via an outlet slot 60, again having a substantial width 56, into a rigid container 62, which may be made of a transparent plastic and through which the blood flows in the form of a broad, substantially flat belt or film ..

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Through an inlet 64 heat exchange solution is conveyed into the heat exchanger 54 and introduced via a manifold 66 in the blood flow paths opposite and interleaved pockets 68 which are defined by the heat exchanger wall and in which, if desired, sieves 69 may be provided. In the illustrated embodiment, the manifold 66 also has the same width 56 as the blood flow path.

The spent heat exchange solution enters from the heat exchanger 54 into a manifold 56, also of width 56, to be collected by a conduit 70, which in turn is connected to a discharge conduit through which the spent solution can be passed to a suitable temperature control device for a further passage through the heat exchanger 54 to be heated or cooled.

The container 62 has a downwardly sloping bottom 72, on which flows out of the outlet of the heat exchanger 54 wide band of oxygenated and temperature-controlled blood. The blood flows in a thin ribbon through the. Outlet 60 of the heat exchanger and with the same width as at the outlet 60 through the inlet 61 into the container 62 and over its sloping bottom 72, to a blood mass 74, which is contained in a vertical tube leg 76 of the container 62.

If desired, a blood defoaming sponge element in the form of a plastic mat may be placed on the floor 72 to promote bubble separation and uniform flow.

The outlet 78 from the container, which is located at the bottom of the vertical tube leg 76, may be connected to an arterial line for the return of the blood to the patient.

Thus, as the blood in the form of the thin ribbon flows down over the sloping bottom 72, there is sufficient opportunity for separation of minute bubbles from the blood before it reaches the comparatively quiescent blood mass 74, in which blistering may also occur.

Advantageously, the inflow and outflow flow rate of the blood are adjusted by the diffusion device according to the invention so that the level of the blood mass 74, as shown, overflows slightly above the vertical tube leg · 76, so that the blood must cover a large flow path over the bottom 72 and reached the blood mass 74 without excessive, bubble-producing turbulence.

Preferably, the largest depth 63 of the container 62 adjacent to the tube leg 76 is not more than half of the width 56th

The gas bubbles may escape through vent openings 78 provided in the top of the container 62, which are preferably defined by a microporous, hydrophobic material having an effective pore size of at most about 5 μm, e.g. .Polypropylenpapier or the like, are closed. In this way, gases can be vented from the container 6 2 while preventing entry of contaminants into the container via the vent openings 78,

A shunt or bypass line 80 is advantageously comprised of a flexible tube or tube having rigid fittings 82, 84 provided at the ends, which in turn are connected to the blood inlet 40 of the oxygenator and to the lower end of the vertical tube leg 76 of the container 6 2, respectively. Shunt 80 is normally terminated by a hemostat or the like.

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stuck. However, upon completion of the oxygenation process, this conduit may be opened to facilitate complete outflow of the blood from the diffuser through the outlet 78.

The oxygenator 12 may be conveniently configured such that the blood flow paths of the sheaths 16 are about 108 mm long, 0.64 mm thick (Figure 2), and 152.4 mm deep (Figure 1), in this manner provide the required membrane surface that meets the ventilation needs of an adult patient. '

The width 56 may be 190.5 mm, thus providing a system with extremely low pressure drop, uniform flow, and highly efficient oxygenation and temperature control performance. The container 6 2 may also have a width of 190.5 mm, so that it can flow through the band-shaped blood stream without turbulence and .Gasbläschen can be separated on the sloping bottom 72.

Of course, the invention is by no means limited to the illustrated and described embodiment, but numerous changes and modifications accessible.

Claims (20)

Invention claim: A blood diffusion system membrane diffusion device characterized by first blood flow paths (16) disposed in nested diffusion exchange relationship with a number of second fluid flow paths on opposite sides of a semipermeable membrane (14) and communicating with an inlet and an outlet, respectively through a heat exchanger (54) with inlet and outlet and with a device connecting the outlet of the first flow paths with the inlet of the heat exchanger, through a rigid container (62) with inlet and outlet and the outlet of the Wärmetauscherε (54) with the Container inlet connecting means for defining a blood flow circuit through the membrane diffusion device, the heat exchanger and the container, and in that the blood circulation perpendicular to the directions of blood flow of inlet. (Start) to the outlet (end) has a substantially constant width. , 2. Device after point. 1, characterized in that said width is at least twice as large
the depth of the blood (circulation) cycle through the heat exchanger. 3. Device according to item 1 or 2, characterized in that the container has a container from the inclination obliquely downwardly inclined bottom. 4. The device according to item 3, characterized in that the container has at its end remote from its inlet end a substantially vertical, tubular channel or conduit section, on whose .Unterseite the container outlet is arranged. 5. The device according to item 4, characterized in that the heat exchanger has a tortuous metal heat exchange wall that the blood circulation through a first set
runs from pockets on one side of this wall and
that the outlet of the heat exchanger during operation in a position perpendicular to the membrane diffusion device is alignable. 6. Device according to item 5, characterized in that it represents an oxygenator for blood. 7. A device according to claim 6, characterized in that an abblirunbare blood shunt line is provided, which between the blood path inlet of the Membranbriffusionsvor- , direction and the container outlet runs. 8. The device according to item 7, characterized in that a vertically arranged blood line is provided, which communicates with the bloodstream inlet of the membrane diffusion device
communicated. 9. Device after funk't; 4, characterized in that the greatest depth of the container at a location remote from the substantially vertical pipe (76) or not located thereon is not more than half the width of the blood circulation through the container. 10. The device according to item 5, characterized in that the pockets of the heat exchanger, through which the blood (flow) circuit runs, are free of sieve elements. 11. The device according to item 10, characterized in that the rigid container is vented in an upper region thereof to the outside. 12. The device according to item 11, characterized in that the vents are closed with a porous, hydrophobic material having pores with an effective diameter of virtually not greater than 5 microns to allow leakage of gases, an ingress of contaminants from the outside in However, to prevent the container. 13. A blood diffusion device, in particular according to one of the preceding points, comprising a diffusion-transmitting, semipermeable membrane folded into a stack in the form of a plurality of membrane layers, having a blood flow over a plurality of first parallel flow paths and a flow of another fluid via a plurality of second parallel flow paths disposed between the first flow paths and separated by the membrane therefrom, and with a rigid, one-piece pad having transverse substantially parallel flight or crease lines and folded in sections along these crease lines and in the second mentioned flow 105 5 5 is arranged on one side of the membrane to support the membrane layers, and which is provided with spaced-apart openings for facilitating a fluid passage, characterized by provided on both edges of the rigid pad, laterally or transversely arranged tabs which inwardly against the inner portions of the pad folded over and glued to form double thick edge portions of the pad with this, so that they form at the opposite membrane edges spacers and sealing elements. ' 14. The device according to item 13, characterized in that the spacers between the pad and the membrane are arranged so that they favor a fluid flow between the two. 15. Device according to _: Item 14, characterized in that the spacers overlap the rigid, one-piece pad each between the openings and that the pad and the spacers are in turn occupied by the semi-permeable membrane, which is so wide and oriented so that they Spacer and the openings overlaps. 16. Device after point. 15, characterized in that the folded base, the Abstand..and the membrane are housed in a close fitting to this arrangement housing, wherein the spacers formed by the folded tabs and sealing elements compared to the rest of the folded stack of an increased compression are subjected. 17. Device according to one of the points 13 to 16, characterized in that the tabs are dimensioned so that they do not cover the openings in the pad. 18. A process for treating a rigid, one-piece, thermoplastic-coated substrate provided with transverse substantially parallel fold or crease lines and spaced apertures to permit fluid flow through the diffusion system after folding into one flexible arrangement with a flexible, semipermeable membrane, characterized in that the edges of the rigid support are crimped inwards, to form on their edges a double thickness of the support defining overlapping tabs, that the thermoplastic coating on the tabs at the edge of Pad thermally softens or is melted and that the folded tabs are pressed against the rest of the pad, so that the tabs bonded by means of the thermoplastic coating surface with the adjacent areas of the pad and thereby at the edges of the base Absta ndhalte-sealing elements are set. 19. The method according to item 18, characterized in that the substrate is then covered with spacers in areas between the openings distributed at intervals, on which a diffusion membrane of such width and in such an arrangement is placed on the substrate and the spacers that they the spacers and the apertures overlap and that then the pad with the spacers and the membrane is folded together by folding along the substantially parallel fold or crease lines to (or zigzagged) pleated sections which form a diffusion membrane stack; Let dense sealing elements form compared to the rest of the stack of increased thickness, so that when inserting the stack into a tight-fitting housing a seal to the opposite edges of the stack is produced. 20. The method according to item 19, characterized in that the tabs are dimensioned so that they do not overlap the openings of the pad. drawings