SE441414B - DIFFUSION SYSTEM FOR BLOOD ACIDIZATION - Google Patents

Description

79005 42-7 l0 15 20 '25 30 35 2 good mix. As a further advantage, it can be mentioned that the reservoir, which is included in the system, forms a highly efficient bubble trap, which can remove larger amounts of gas bubbles than the previously known bubble traps.

According to the invention, there is provided a diffusion system for blood, which system comprises a membrane diffusion device with a plurality of first paths for blood, which are arranged between and in diffusion exchange relation to a plurality of second fluid paths on opposite sides of semipermeable membrane elements. The first and second courses communicate with each inlet and outlet.

A heat exchanger with an inlet and an outlet is also provided, together with means for connecting the outlet of the first flow paths of the membrane diffusion device to the inlet of the heat exchanger.

A rigid reservoir, which has an inlet and an outlet, is connected with its inlet to the outlet of the heat exchanger.

The membrane diffusion device, the heat exchanger and the reservoir thus form a circuit for blood flow.

According to the invention, this blood circuit defines a substantially constant width, perpendicular to the direction of the blood flow, from its beginning, at the inlet of the path of the blood flow in the membrane diffusion device, through the reservoir. In other words, there is no congestion of the flow path of the blood in a tubular conduit between the membrane diffusion device and the heat exchanger or between the heat exchanger and the reservoir. This feature provides benefits in both cases.

First, the flow-distributed blood entering the heat exchanger in a wide flow pattern promotes uniform blood flow through each of the flow paths in the heat exchanger. The heat exchanger may be, for example, of the type discussed in U.S. Pat. No. 3,640,340, which has a metal wall in heat exchange relationship with the blood circuit extending through a first set of pockets on one side of the heat exchange wall. In heat exchange fluid passes through intermediate pockets on the other side of the heat exchange wall. Depending on the uniform and wide blood path across the entire width of the heat exchanger, the flow through the individual pockets or the other blood paths in the heat exchanger can be made more uniform. Thanks to this, shielding for flow distribution can be eliminated from the bloodstream in the heat exchanger.

This in turn creates a reduced pressure drop in the heat exchanger, but enables even blood flow.

Second, a reduced width of blood flow from the heat exchanger to the reservoir actually creates an empty, non-turbulent band of blood, which preferably flows along a sloping bottom of the reservoir downwards, towards a blood storage column, the reservoir outlet being at the bottom of columns. The thin, broad band of blood, which flows across the sloping bottom of the reservoir, creates an excellent opportunity for removal of bubbles from the blood, while the relatively stagnant blood column with its bottom outlet port creates an additional opportunity for removal of bubbles. In crisis situations, when abundant bubbles were introduced into the blood, these bubbles can thus be removed from the blood in the reservoir, whereby the gases are discharged from the reservoir via ventilation means.

Consequently, a safe, efficient blood diffusion system, and especially in an oxygenation system, can be created in accordance with the invention, which system has a low pressure drop, enables the use of fewer and weaker capacity pumps in the system and causes less stress on the blood cells.

The invention further represents a further improvement of pleated diaphragm types, where an integral spacer is formed at the opposite ends of the flow paths through the pockets of the pleated diaphragm, thereby eliminating the need for a taped seal or relatively complicated techniques for sealing ducts. the folds of the pleated membrane stack, formed in accordance with the aforementioned patents, are eliminated.

As a result, the pleated membrane stack can be assembled more efficiently, with the same or improved possibility of sealing at the ends, thanks to the integral spacer elements according to the invention.

According to the invention, the membrane diffusion device is folded into a stack for providing a plurality of membrane layers, arranged for blood flow in a plurality of parallel, first flow paths, and for flow of another fluid in a plurality of parallel, second flow paths, arranged between but separated from the first flow paths of the membrane. A rigid, one-piece support with transverse, substantially parallel notched lines is folded along the notch lines into sections, and is arranged on one side of the diaphragm in the other flow path for supporting the diaphragm layers. The support also defines separate ports for fluid flow.

In accordance with the invention, side flaps are provided on each edge of the rigid support, which flaps are folded inwards against other portions of the support and are thereby sealed.

The effect of this is that the support has edge portions with double thickness, which create a distance and a sealing gasket at opposite edges of the folded stack.

Preferably, the rigid support is coated with a thin film of thermoplastic, such as polyethylene. At a suitable time of the folding process, the thermoplastic cover on the flaps is heated, for example by means of hot air, to soften the thermoplastic cover on the flaps next to the edge of the support. The folded flaps can then be pressed into other portions of the support, so that the cover causes the flaps to adhere to the rest of the support.

When the support is then folded along the transversely extending cut lines to provide the above-described stack of membrane layers with intermediate support sections, the double thick edges of the support form a separating and sealing gasket along the support. edges. Preferably, before the folding of the support, a spacer is laid over the support between the separated ports. the diffusion membrane, which has such a width and orientation that it lies over the spacers and the gates, is then laid over the support and the spacers. Then the support, the spacers and the diaphragm can be folded; as described, folded sections by folding along the cutting lines, to provide a diffusion membrane stack with intermediate sections with the support and membrane pockets, the folded flaps serving as a packing element of greater thickness than the rest of the stack, so that insertion of the stack in a tight housing provides a seal at the opposite edges of the stack.

The invention is described in more detail below with reference to the accompanying drawings. Fig. 1 is a view of a diffusion system according to the invention for blood oxygenation. Fig. 2 is a view of the system of Fig. 1, rotated 90 ° about its vertical axis. Fig. 3 is a longitudinal sectional view of a flow-through envelope, showing a portion of the oxygen and blood flow path in the membrane diffusion device used in the embodiment of Fig. 1. Fig. 4 is a plan view of the membrane support and related portions defining the envelope in the device of Figs. Fig. 5 is a perspective view of the diffusion system of Fig. 1. Fig. 6 is a sectional view taken along line 6-6 of Fig. 2.

Reference is now made to the drawings, in which a diffusion system 10 includes a membrane diffusion device 12, which may be designed in accordance with U.S. Pat. Nos. 3,879,293 and 3,757,955.

The membrane diffusion device or oxgenator 12 preferably comprises a porous, hydrophobic membrane, for example of polypropylene and with small pores in the submicron class, which allow unobstructed gas passage through the membrane but prevent passage of liquid blood. The porous, hydrophobic membrane 14 is formed into a large number (preferably about 75) of separate flow envelope 16 by placing the membrane on a flat support 18, as described in the above-mentioned patents. , which support preferably consists of cardboard treated with polyethylene or similar thermoplastic.

In the specific embodiment, a mesh strip 20 is laid over the support 18, whereupon the membrane 14 is laid on the support, and the latter is folded into a series of panels 22 along fold lines 24, so as to form a series of windings, as described in the above-mentioned patents. , which form the interconnected, separate envelopes or pockets 16. The bloodstream runs between sections 14 of the membrane in each envelope 16, from the edge 31 to the edge 33 of the envelope, while the oxygen path is between the support sections 22 and the membrane section 14, below percolation through the network 20.

An additional net 26 can be placed in the path of the blood stream in each connected envelope 16.

The support 18 has longitudinally extending cut-away portions 28 in which the parts of adjacent panels 22 can cooperate with each other, as illustrated in Figs. 20-22 of U.S. Pat. No. 3,757,955, thereby forming continuous distribution channels which facilitate the flow of oxygen. and blood in and out of each envelope.

Additional flaps 30 are provided at each edge of the support 18, which flaps are provided for inward folding along the fold lines 32 to provide a sealing gasket at the ends of each envelope. The carton material in the support 18 can be coated with a relatively low melting polyethylene material or the like, so that the flaps 30 can be heat sealed to a folded position by melting the polyethylene.

The side edges of the support 18 can be covered with a double-sided adhesive tape. The relatively narrow net 20 is laid between the taped edges. Then the membrane 14 is applied with edges adhering to the tape. The assembly is then folded into an accordion fold along the lines 24, and the net 26 can be fed to the envelope 16 formed in this way, connected 10 15 20 25 30 35 7900542-7 7. While the assembly is folding, strands of RTV sealant can be applied along the membrane edges for improved sealing.

The heat sealing step can be performed simply by blowing hot air on the flaps 30 and the edges of the support 18, so that the polyethylene coating melts. The folded paper support 18 can pass through the hot air jet, whereupon the folded flaps 30 are pressed down into the rest of the support 18 for adhesion, when the polyethylene cools.

The technique described above eliminates the need to use an tape to provide end spacers and end seals for the envelope and replaces the manual process required for this use with such a process, which can be performed fully automatically.

Alternatively, the hot air technique can be replaced by spraying glue, if desired, to adhere the flaps 30 to the support 18.

The hot air blowing can also be used to attach the nets 20 to the carton by softening the polyethylene in the central portion of the carton or by softening the nets.

As shown in Fig. 4, it is preferred that the net 20 have such proportions that it can be laid between the separate, longitudinally extending portions cut away in the vicinity of the opposite edges of the support 18. This prevents the openings 28 from being blocked by the net 20.

Similarly, the flaps 30 are preferably proportioned so that they also do not overlie the cut-away portions 28. In contrast, the membrane 14 which is laid on the support after the net 20 is preferably so proportioned that it approx. corresponds to the width of the support 18, after the flaps 30 have been folded inwards, as shown in Fig. 4, in order to facilitate the sealing of the edges of the membrane 14.

The assembly of the stacks of semipermeable membranes and supports forming individual envelopes 15 can be a continuous, automated process, using rollers of the support 18, the net 20 and the membrane 14 and conventional new rollers and the like are provided to control the progress of the assembly.

The one-piece stack of interconnected envelopes 16 is placed in a canister 34, which is closed by a lid 36, in accordance with U.S. Pat. No. 3,879,293, so that the overlying flaps 30 in the stack are tightly clamped during sealing of the ends. A gas inlet 35 is provided for connection to an oxygen source, which inlet directs gas through a gas inlet opening 37 to the envelope stack. A gas outlet 38 receives the exhaust gas from a gas outlet opening 39 in the device and diverts the exhaust gas from the apparatus.

A blood inlet 40 also has a wide opening, as shown in Fig. 2, and receives blood from a vertical conduit 42, which has means for fixation on a flexible conduit, which receives venous blood from the patient. A connector 44 communicates with the blood inlet 40 and can be connected to a cardiotomy suction for surgery.

The purpose of the vertical line 42 is to provide a pressure level created by the blood in the line 42 and thereby always a predetermined blood pressure in the ox generator 12, when the line 32 is filled with blood. The blood enters the ox generator, passes through the wide inlet opening 40 which, as shown in Fig. 2, extends over substantially the entire width of the ox generator. The blood then flows in the direction of the arrows 46 to the interconnected envelope 16 and then passes in a wide front in the direction of the arrows 48 over the length of the envelope. The blood then moves in the direction of the arrows 50 and leaves the envelope 16 at their other end through the wide blood outlet 52, which communicates directly with the wide blood inlet 58 to the heat exchanger 54.

The blood flow path through the heat exchanger 54 has the same width as the flow path as the ox generator 12, in the direction perpendicular to the directions 48, 50 and 54 for the blood flow, as shown in Fig. 2. This is equal to the width of the corresponding blood flow path through the envelope 16, the outlet port 52 from the ox generator, and the inlet port 58 to the heat exchanger.

The heat exchanger 54 may have the same design as the wall-mounted heat exchanger according to US-PS 3,640,340, but the heat exchanger used here preferably contains about 58 pockets or blood passages 59 in the pleated wall for the blood flow and thus has a substantially greater width. and less flow resistance than the embodiment shown in the aforementioned patent specification.

The blood channels 59 in the heat exchanger 54 are preferably free from current distribution shielding or: nets or other means for increasing the flow resistance in order to achieve a more even flow in the various current channels in the heat exchanger. This is possible by the wide connection opening on the blood outlet 52 from the ox generator 12 and the blood inlet 58 to the heat exchanger 54 greatly reducing the non-uniformity of the flow in the passages 59, so that shielding is made impossible.

The blood passages or channels 59 may, for example, be 1.58 mm thick, 12.7 mm deep and 108 mm long in the heat exchanger.

The blood flows from the channels 59 in the heat exchanger 54 through an outlet slot 60, which also has a substantial width 56, and to a rigid reservoir 62, which may consist of a transparent plastic material, so that the blood flows in the form of a wide, substantially flat band. , as it flows through the reservoir 62.

Heat exchange solution can be pumped to the heat exchanger 54 through the inlet 64, which solution is distributed by means of a distributor 66 to the opposite set of pockets 68, which are defined by the heat exchanger wall which lies between and in heat exchange relationship to the blood streams. Network 69 can be used if desired. In this embodiment, the distributor 66 has the same width 56 as the blood flow path. The spent heat exchanger solution flows from the heat exchanger 54 to the collector 68, which also has the width 56, and is collected in a conduit 70, which in turn may be connected to a receiving conduit for transport. port of spent heat exchanger solution back to a suitable temperature control device for heating or cooling the fluid for renewed flow through the heat exchanger 54.

The reservoir 62 has a downwardly sloping floor 72 which receives the wide band of oxygenated and temperature controlled blood flowing from the outlet of the heat exchanger 54. The blood in the reservoir 62 flows in a narrow band through the outlet 60 of the heat exchanger, through the inlet 61 to the reservoir. which has the same width as the outlet 60, and then on the inclined floor 72. This causes the blood to flow in a narrow band, until it reaches the pool of blood 74, which is in a vertical, tubular leg 76 for the reservoir.

If desired, a blood-foaming plastic sponge material can be placed as a mat on the floor 72 in order to promote bubble removal and uniform flow.

The outlet 78 from the reservoir is arranged at the bottom of the vertical, tubular bone, and can be connected to an arterial conduit for returning the blood to the patient.

Consequently, when the blood flows down the floor 72 in a thin strip, there are plenty of opportunities for the removal of microbubbles from the blood, before the blood reaches the relatively still pool 74, where bubbles can also be removed.

It is preferred that the inflow velocity and outflow rate of the blood through the diffusion system of the invention be adjusted so that the level of the blood pool 74 slightly overflows the vertical leg 76, as shown, in order to give the blood a long flow path across the floor 72 and to unite the blood. with the pool 74 without bubbles which creates unnecessarily large turbulence. Preferably, the maximum depth 63 in the reservoir 62 at locations separate from the leg portion 76 is not greater than half the width 56.

Gas bubbles can be vented through ventilation openings 78 in the upper wall of the reservoir 62. Preferably, the openings 78 are closed by means of a microporous, hydrophobic material, which has an effective pore size of not more than about 5 μm, for example polypropylene paper or the like. Consequently, gases can escape from the reservoir 62, while contaminants outside the reservoir are prevented from entering the reservoir through the ventilation openings 78.

A shunt line 80 preferably consists of a flexible hose, which at the ends is provided with a rigid connection piece 82, 84, which in turn are connected to the blood inlet 40 of the ox generator or to the bottom of the vertical leg 76 in the reservoir 62. The shunt line 80 is normally clamped by means of a hemostat or other clamping element. The line 80 can be opened at the completion of the oxygenation process to facilitate complete draining of blood from the diffusion system through the outlet 78.

The blood flow paths in the envelope 16 of the oxygenator 12 are approximately 108 mm long and 0.64 mm thick (as shown in Fig. 2), and 152 mm deep (as shown in Fig. 1), thereby providing the desired membrane area for the respiratory needs of an adult patient.

The width 56 can be 190 mm to provide a system with extremely low pressure drop, uniform flow and with highly efficient oxygenation and temperature control possibilities. The reservoir 62 may also be 190 mm wide for receiving the band-shaped stream of blood without creating turbulence and for removing gas bubbles along the sloping floor 72.

Claims (10)

É7900542-7 LO 15 20 25 30 '12 PATENTKRAV 1. 'l. Blood diffusion system with a membrane diffusion device comprising a plurality of first blood flow paths arranged between and in a diffusion exchange relationship to a plurality of second fluid flow paths on opposite sides of a semipermeable membrane element, the first and second flow elements lanes communicate with their respective inlets and outlets; heat exchange means having an inlet and an outlet; and means connecting the outlet of the first flow paths with the inlet to the heat exchange means, characterized in that the diffusion system further comprises a rigid reservoir with an inlet and a means connecting the outlet of the heat exchange so that the car outlet; the means with the inlet to the reservoir, a blood flow circuit is passed through the membrane diffusion device, the heat exchange means and the reservoir; wherein said blood circuit has a substantially constant width, perpendicular to the directions of the blood flow, from its beginning to its end. 2. A system according to claim 1, characterized in that said width is at least twice as deep as the depth of the blood circuit through the heat exchange means and that the reservoir has a floor sloping down from the inlet of the reservoir. System according to claim 1 or 2, characterized in that the reservoir has, at an end remote from the reservoir inlet, a substantially vertical, tubular channel part, the outlet of the reservoir being arranged at the bottom of this channel part. 2 or 3, as a result of which the heat exchange means are defined A system according to claim 1, characterized in that a pleated heat exchange wall of metal, that said blood circuit extends through a first set of pockets on one side of the heat exchange wall and that the heat exchange means of the heat exchange means outlet during use is located at a vertically elevated level above the membrane diffusion device. System according to any one of claims 1 to 4, characterized in that the membrane diffusion device is a blood oxygenator, which comprises a compressible shunt line for blood, which line extends between the inlet of the blood flow path to the membrane diffusion device and the outlet from the reservoir, and a vertical blood line, which communicates with the inlet of the blood flow path to the membrane diffusion device. System according to claim 3 or according to claim 4 or 5 in combination with claim 3, characterized in that the maximum depth of the reservoir at a position separate from the substantially vertical channel part is not more than half the width of said blood flow. circuit and that the rigid reservoir at an upper part has ventilation openings towards the surroundings, which openings are closed by means of a porous, hydrophobic material, the pores of which have an effective diameter of not less than substantially 5 μm, so that gases can be vented away and supply of pollutants from the surroundings to the reservoir can be prevented. A diffusion system according to any one of claims 1-6, wherein said membrane diffusion device has a flexible, semipermeable membrane folded into a stack to provide a plurality of membrane layers arranged for blood flow in a plurality of parallel, first flow paths, and for flowing another fluid in a plurality of parallel, second flow paths, which are located between and separated from the first flow paths by the membrane, and a rigid, one-piece support, which in the transverse direction has substantially parallel cut lines and which is folded along these lines to sections and arranged on one side of the membrane in the other flow path for supporting the layers, as well as separate ports in the support for enabling fluid flow, characterized therefrom, 14 to laterally separate flaps on each edge of the rigid f the support are folded inwards and sealed at the inner parts of the support to provide double tenc k ant portions on the support, which form a spacer and a sealing gasket at opposite edges of the stack. 8. A system according to claim 7, characterized in that the spacer is arranged between the support and the membrane to facilitate fluid flow between them. 9. A system according to claim 8, characterized in that the spacer lies over the rigid, one-piece support in a position between said ports and that the semipermeable membrane lies over the rigid one-piece support and the spacer, which membrane has such a width and orientation, that it lies over the spacer and the gates. 10. A system according to claim 9, characterized in that the folded, rigid, single-piece spacer and the semipermeable membrane are arranged in a tight-fitting housing, whereby the spacer and the sealing gasket, formed by the folded flaps, are subjected to an increased compression in relation to the rest of the folded stack, and that the flaps are so dimensioned that they do not lie over the gates.