DE3001018A1 - BLOOD OXIGATOR - Google Patents

Description

PATENT LAWYERS
Dlpl, Ing. P. WIRTH Dr. V. SCHMIED-KOWARZIK

Dlpl.-lng. G. DANNENBERG Dr. P. WEiNHOLD ■ Dr. D. GUDEL Dipl.-Ing. S. Schubert

281134 ti. GR. ESCHENHEIMER STR. 39

* 6000 FRANKFURT AM MAiN

January 11, 1980 Gu / Ar / ki

Baxter Travenol
Laboratories, Inc.
One Baxter Parkway

Deerfield, Illinois 60015 USA

Blood oxygenator

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Description :

The invention relates to a blood oxygenator with which the Blood outside the body can be enriched with oxygen and heated in a controlled manner during operations.

Such blood oxygenators are common in operations. she serve to enrich the venous blood with oxygen so that the oxygen reacts with the hemoglobin of the blood, whereby the oxygen is then absorbed and carbon dioxide is given off. A historical overview of blood oxygenators is in the December 1961 issue of Surgery magazine under the title "Theme and Variations of Blood Oxygenators "by R.A. DeWall et al.

There are three types of blood oxygenators. With the so-called membrane oxygenator a semi-permeable membrane is provided that separates the blood from the oxygen. The gas exchange takes place through Diffusion takes place through the membrane. Such an oxygenator is described, for example, in U.S. Patent 3,413,095.

The second type of blood oxygenator involves exposing a thin film of blood to an atmosphere of oxygen. An example of one such blood oxygenator is in the issue of December 15, 1956 The Lancet, page 1246, under the heading "Design of An Artificial Lung Using Polyvinyl Formal Sponge", described.

The third type of blood oxygenator delivers oxygen vesicles directly to the blood. In the case of a vesicle oxygenator of the US-PS 3,578,411, the vesicle chamber has a continuous, tortuous flow path that allows the blood to mix with the oxygen is supported. U.S. Patent 3,807,958 describes a vesicle oxygenator comprising a plurality of vertical tubes used, through which the mixture of blood and oxygen

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increases. U.S. Patent 3,898,045 describes a blood oxygenator with a lattice chamber that is tightly packed with balls that are supposed to improve the gas exchange. With the one in one Article from August 1957 in "Surgery" described vesicle oxygenator with the title "Preliminary Studies On the Sponge Oxygenator" by Adriano Bencini et al there is a long needle with many openings in a cylindrical piece a sponge made of polyurethane. U.S. Patent 4,067,696 describes a blood oxygenator wherein an upward flow a mixture of blood and oxygen flows through a three-dimensional material with open cells, creating the Gas exchange on the hemoglobin is to be improved.

The invention is based on the object of proposing a high-performance blood oxygenator that, as a structural unit brings significant clinical benefits. The assembly should be inexpensive to manufacture and prior to use can be sterilized. It should therefore be available quickly. The novel blood oxygenator should also be an essential have rigid housing so that it essentially maintains its dimensions. It should look good and inexpensive can be produced by the injection molding process of synthetic polymer. He should also go to Can be thrown away so that it no longer needs to be cleaned. This removes impurities when next use avoided. The unit should be able to be assembled at the manufacturer in such a way that the Quality control can be done in a clean room. Here the oxygenator is put together and then pre-sterilized so that it is ready for use and thus the clinical and economic problems of the There are no efforts to clean the oxygenator.

This problem is solved by the characterizing measures of claim 1. It is therefore important that that the blood foam formed in the oxygenator has a

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Heat exchanger is distributed, from where the blood foam under the action of gravity flows down and to a Defoaming device arrives. Carbon dioxide is made from the Defoamer released upwards, and the liquid blood flows under the action of gravity from the defoamer down into a reservoir for arterial blood.

Preferred embodiments of the invention are specified in the subclaims.

The invention is illustrated below using an exemplary embodiment explained in more detail, from which other important features result. It shows:

Fig. 1 is a plan view of a novel blood oxygenator; Figure 2 is a perspective view of the blood oxidizer

together with a fastening device; FIG. 3 is a view corresponding to FIG. 2, with the blood oxygenator attached to the tripod;

Figure 4 is a section along line 4-4 of Figure 1; Fig. 5 is a partially sectioned view in the direction

the arrows 5-5 of Fig. 4;
6 shows the holding device for the blood oxygenator in detail.

A blood oxygenator 10 is a completely assembled unit with low manufacturing costs, essentially consisting of injection molded parts made so that the oxygenator can be thrown away after use. The housing is essentially rigid. The oxygenator can be pre-sterilized. Because injection molded parts are used, the Oxigenator has the necessary Quality and can be manufactured and assembled cheaply. The parts are clean and of reproducible quality, which is important with such oxygenators.

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In the following the structure and the mode of operation of the new type of oxygenator in the direction of flow of the flowing through it Blood described. Venous blood flows through an inlet 12 which is directed downward. An inlet hose 14 (cf. FIG. 2) can therefore be connected directly to a venous cannula in the patient in such a way that the inlet tube as a half loop so that gas bubbles from the oxygenator do not flow backwards to the patient can. A side connector 16 is provided for connecting a tube 18 from a cardiotome reservoir, when this is used. Without such a cardiotome reservoir, the tube 18 is pinched off. A sample port 19 is Connected via a line 21 to the connection 12, so that venous blood samples can be taken. For the sample syringe a Luer opening is provided.

A mixing device 10 (see in particular FIG. 4) has a cylindrical, tubular body into which a porous tube 22 is used. An outer, tubular cylinder space surrounds the tube and is open to receive oxygen from an oxygen port 24. The interior of the porous tube 22 has substantially the same inner diameter as that the inlet 12 for the venous blood. The tube 22 is porous and serves as a mixing device. The porosity of the tube 22 is critical because it reduces the size of the vesicles supplied is determined. A porosity in the range of "TEGRAGLAS" manufactured by 3M Company, Minneapolis, Minnesota, USA, is correct, although other similar structures can be used. If the oxygen bubbles are too small, the blood is oxygenated but carbon dioxide is not removed. If the oxygen bubbles are too big, so the opposite happens, i.e. sufficient carbon dioxide is drawn off, but the oxygen enrichment is sufficient not from. With the specified porosity, a ratio of the gas flow to the blood flow of less than 1: 1 generates the

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correct bubble size. A smaller flow of oxygen is generated smaller vesicles and a stronger oxygenation, or vice versa.

The tubular shape of the mixer ensures that the entire volume of oxygen is evenly mixed with blood without any traumatic symptoms «Because the oxygen vesicles to flow inward to the blood, the blood will flow over the Saturated inner surface of the porous tube

The porous tube 22 can consist of a hydrophobic material or be coated with such a material »This prevents the blood from flowing out through the tube when the oxygen pressure drops» The outside of the tube 22 can also have a coating ₉ that is antibacterial Filter is used to filter out particles larger than 0.2 microns from the oxygen flow. «This coating is a layer of paste that, after drying, results in a porous surface.

Part of the oxygen enrichment and depletion with Carbon dioxide takes place during the initial admixing of the bubbles, namely the blood in the tube 22 foams and when enlarging the foamed mass »The blood with the enclosed oxygen vesicles at the beginning of the oxygen-COg exchange flows upwards, under the action of the gas flow and the buoyancy as well as the inflowing venous blood. A conduit 26 directs this upward flow of blood foam into the top of a dome 28 of a main body 30 of the oxygenator 10 “The dome 28 is part of the cover of the lower part of the housing. Within the dome 28, a flat manifold plate 32 takes the Blood foam on. The blood foam flows horizontally across " the distribution plate 32. Here, the blood foam can be viewed through the transparent dome 28 Degree of oxygen enrichment due to the different red

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See the color of the blood. If the flow of venous blood is uneven, for example because the suction is too strong, are Foam waves visible, which run over the distributor plate 32. This thus makes a good display means for the doctor who then the inflow rate throttles.

The flow path for the blood foam is tortuous, which ensures good mixing and good gas exchange will. As a result, small amounts of oxygen can be used per unit volume of blood. These small proportions in turn cause less movement of the blood and thus less traumatic damage to the blood cells. This Furthermore, a low ratio produces less foaming, so that less defoaming is necessary; Besides that this reduces the cost of oxygen.

A flat manifold plate 32 is approximately 1/4 "from that Outer wall of the dome 28 is arranged. The blood foam is thus distributed over the edges and flows from there by means of gravity onto a perforated distributor plate 34. The flow space 36 around the edge of the flat distributor plate 32 allows that the blood foam flows downwards without a large accumulation of gas bubbles occurring. Holes 38 of the plate are circular or designed as slots. If slots are provided, these can be radial or be provided angularly or also distributed arbitrarily, so that the foam is distributed uniformly when it passes through the holes 38 flows downwards.

A thin, disk-shaped dispersion layer 39 made of a foam material can be attached to the underside of the distributor plate 34 and be provided above a heat exchanger 40. The foam has open cells so that the blood foam can flow through it can. The layer 39 does not need to be coated and therefore acts as a distributor for the blood foam over the heat exchanger 40 evenly distributed. However, it is preferred

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when layer 39 is coated with silicon. This silicon coating conducts the gas / liquid separation from the blood foam. This improves the contact of the liquid blood with the coils of the heat exchanger, whereby the efficiency of the heat exchanger is increased. But the shift is not always necessary "

The heat exchanger 40 consists of a pair of spirally wound flat tubes. A cone 42 in the center of the coil is provided so that the blood through the central part of the heat exchanger can not pass therethrough. The coils of the heat exchanger 40 are in mutually opposite spirals in the two layers wrapped ₉ and indeed on a mandrel, whereby the inner Opening is formed into which the cone 42 is inserted. The coils have small spaces 44 between their layers. If they are wound in opposite directions, small spaces arise between the windings of the two layers. These spaces allow the blood foam to flow downwards between the coils, in which case the heat exchange then takes place.

The coils are laid out horizontally, this results in a slow, parallel blood flow on the surface of the coils and through the openings between the windings. Also because of this the blood cells are damaged less. The horizontal arrangement of the heat exchanger reduces the overall height of the oxygenator and increases the volume of the arterial blood reservoir. The coils can be coated with silicon, whereby the wetting of the coils with the blood is improved without the entrained gas bubbles preventing the heat transfer hinder.

The points at which the tubes of the heat exchanger pierce the housing of the oxygenator are above the level of the blood in the oxygenator. This simplifies the seal leadthrough there, and this results in leadthroughs

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no blood loss. There are no connecting pipes within the housing 30, but rather both free ends of the heat exchanger are led out of the housing. 1-4 show that the coil ends 46 and 48 are bent downward. Through this Connections for water, for example connections 50 and 52 (see FIG. 2) for heating water, can be connected. Because no connection pieces are provided within the housing, no water can penetrate into the blood. because the coil ends are bent down, the water can be drawn off by gravity. As a material for the heat exchanger Aluminum tubes with an outside diameter of 3/8 "or 1/2" are preferred. This material can be deformed easily and sterilized. It is inexpensive and has good heat transfer. However, other materials can also be used be used.

A defoaming device 54 is located in the housing 30 below the heat exchanger 40. The blood foam flows off Heat exchanger over its entire surface to the defoaming device 54. For this purpose, an open-pored synthetic Polymerisate provided, for example "Scottfoam", i. a silicon-coated polymer. Due to the surface effect of the silicon, trapped gas is released liquid blood separated so that the gas escapes upwards and can be run out of the housing. There is one for this Ventilation opening 56 provided in the dome or cover 28, through fluids and drugs can be delivered. A gap 60 is provided on the circumference of the dome 28, which is around extends the tip of the main body of the oxygenator.

A vent port 58 is provided so that negative pressure can be applied to remove harmful gases from the oxygenator suck off. It has been shown that anesthetic gases trapped in the blood together with the carbon dioxide escape, so that the operating personnel through these gases

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Can be damaged. The vent connection 58 enables the gases to be sucked off separately. The dome 28 seals the main body 30, with the exception of the gap 60, which serves as a vent opening so that the gases can freely escape into the atmosphere. This deduction is provided ^ when the gases to escape into the operating room ", when negative pressure applied to the vent port 58 v / ith ₉ so free air is sucked into the gap 60 ,, v / odurch a lowering of the internal pressure in the oxygenator 10 prevents

The cathedral 28 has a downwardly extending apron 62 " The apron guides the downwardly flowing blood foam onto the top of the defoaming device 54. Simultaneously a line is thereby formed through which the separated gases can escape. There is also a Defoaming sponge 64 in the annular space formed there provided so that no blood foam enters a chamber 82 or outside the oxygenator through the connections 58 or 60 can flow.

A shell 66 supports the lower part of the body of the defoaming device 54. An outer wall 68 of the shell holds the sponge on the outer periphery. The shell 66 has feet 99, with which the shell rests on the housing of a reservoir 82 of the body 30th Gases or blood can flow between the upper and lower parts of the oxygenator 10. A filter section 72 is a part of the shell and is conical or cylindrical and has a bottom 74. The filter section 72 has its interior space open to the space above the shell 66 and can hold a defoaming body 76. A filter 80 made of woven material has a low flow resistance for the blood flowing through there, which flows from the defoaming body 54 downwards into the interior of the filter section 72. Alternatively, the filter section can be shaped as a homogeneous, porous structure. That through the filter

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80 from the filter section 72 outwardly flowing blood therefore subjected to a final filtration. The filter 80 is preferably a woven mesh structure made of a blood compatible material Polymer with a preferred porosity between 100 and 250 microns. The filter material is soaked in the blood, so that When wet, the gas bubbles cannot flow through the filter. So this is where the last separation takes place of the gas takes place from the blood, the gas remaining on the inside of the filter section 72. The reservoir 82 for arterial Blood is open at the top, so that gas that may still get there through the opening between the bowl and the shoulder 70, which opening is formed by the feet 99, can be derived through it.

The arterial blood reservoir 82 has a larger volume at the top, which is formed by shoulders 108 and 84 and a smaller volume at the bottom formed by the tapered body 86 of the reservoir will. This shape gives greater resolution at the bottom and greater storage capacity at the top. the The top suddenly widens at shoulder 84. This, however, is at a level that is above normal blood levels is located. So if additional blood capacity is suddenly required, it is available there, little additional vertical space is required for this. There is more space in shoulder 84 up to Overflow of the reservoir through gap 60.

An outlet pocket 88 is formed on the underside of the tapered body 86 of the reservoir. Outlet connections 90 and 92 are provided for connection to outlet hoses 94 and 96. The connection 92 for arterial blood and he connection 96 for arterial blood deliver blood to the arterial pump and from there to the patient. The connections 90 and 94 serve as coronal perfusion outlets. A plate 98 prevents turbulence and is located above the outlet

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pocket 88 to prevent the formation of eddies “The blood flow is undisturbed around the edges of the plate. The plate enables “that the blood level can be lowered considerably lower in the reservoir 82 ₉ without the risk _{9 of} air being sucked into the outlet line by any turbulence” The connections 90 and 92 are directed downwards so that the outlet downwards he follows. The connecting hoses can therefore hang down in a natural curve without kinking.

A sample tube 110 has a Luer opening for taking arterial Blood samples. The samples are taken through a tube that extends inside and near the filter 80 Bottom of the reservoir 82 is located. When air is drawn in through the sample tube 110, the bubbles can be inside of the filter 80 remain and do not get into the reservoir for the arterial blood.

In operation, a console for a heart-lung pump usually has a support rod 100 to which a bracket 102 carrying an open bracket 104 is connected. The bracket 104 fits under a shoulder 70 of the housing 30. The bracket 104 is around a pin 105 pivotable so that the oxygenator can be pivoted. A gap 106 in the bracket enables the Oxigenator can be withdrawn with its hoses. This enables easy operation and positioning of the Oxygenators.

The oxygenator has a shape ₉ that it can be arranged in use near the bottom in such a manner. The blood can therefore be introduced into the oxygenator very effectively. Only a small volume of initial blood is required before the actual operation, which in turn reduces the risk of contamination. The dynamic processes are reduced and the oxygenator responds quickly.

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A recess 97 carries the filter and can be a temperature sensor for the arterial reservoir.

It is therefore essential that the oxygenator can be fully assembled and sterilized by the manufacturer. It can be produced inexpensively and has a high degree of efficiency. It can therefore serve as a disposable unit. The patient's blood is enriched with oxygen as it passes through the center of a tubular, porous mixing device which supplies optimally sized oxygen bubbles Top of the housing of the oxygenator, from where the blood foam flows by gravity downwards past the tube of a heat exchanger ^ The heat exchanger is wound as a flat coil. All its connections are outside the oxygenator housing. A silicon-coated sponge is located below the heat exchanger, so that the blood foam flowing down from there is defoamed when it flows through the sponge.Carbon dioxide and other gases are released to the outside, and the liquid blood flows by gravity into a reservoir for arterial blood that tapers downwards.

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Claims (10)

Patent claims or protection claims: 1J blood oxygenator, marked by - a substantially rigid housing (30), - A foaming device (20, 22) attached to the housing and having a venous blood line (12; 16), an inlet line (24) for oxygen and a porous mixing device (20) in connection with the blood line and the inlet line through which oxygen bubbles are mixed with the venous blood and a venous one Blood foam is generated, - a blood foam line (26) between the foaming device and an upper part of the housing, - A heat exchanger (40) in the housing below the upper part of the housing, with which the temperature of the Blood foam is controlled, with a line (36, 39) for the blood foam to the heat exchanger, - A defoaming device (54) in the housing below the heat exchanger to which the blood foam is fed from the heat exchanger by gravity, and in which the foam is separated into liquid blood and gas, whereby the blood is defoamed, - And through a reservoir (82) for arterial blood with an outlet (92) which maintains in the housing) the Defoaming device is provided and in which the liquid blood is removed from the by gravity Defoamer collects. 030029/0891 2. blood oxygenator according to claim 1,
characterized in that the mixing device (20) consists of hydrophobic material and is essentially tubular, the inlet line (12; 16) for the venous blood extending through the mixing device. 3. blood oxygenator according to claim 2,
characterized in that an oxygen filter (22) is provided on the outside of the mixing device (20), with which the oxygen flowing through there is filtered. 4. blood oxygenator according to claim 1,
characterized in that the heat exchanger (40) is arranged horizontally and essentially spans the flow path of the blood between the blood foam line (26) and the defoaming device (54). 5. blood oxygenator according to claim 4,
characterized in that the heat exchanger (40) consists of a flat wound coil. 6. blood oxygenator according to claim 1,
characterized in that a distribution system (28, 32, 39) is provided which is located above the heat exchanger (40) to which the venous blood foam is fed from the blood foam line (26) and which distributes the blood foam to the heat exchanger, the distribution system has a substantially flat distribution plate (32) without holes, which is located next to the blood foam line (26), and underneath a perforated distribution plate (39), whose 030029/0891 Holes (38) are arranged above the heat exchanger (40) so that the blood foam passes the heat exchanger evenly is fed. 7. blood oxygenator according to claim 1,
characterized in that the heat exchanger (40) has a continuous tube, the ends of which extend through the housing (30) above the level of the blood foam in the housing. 8. blood oxygenator according to claim 1,
characterized in that a funnel-shaped support (78) is provided in the housing (30) below the heat exchanger (40), which supports the defoaming device (54) at the upper end and which tapers downwards and thereby the blood enters the reservoir (82) directs. 9. blood oxygenator according to claim 8,
characterized in that a filter (80) is provided at the lower end of the support (78) with which the blood received from the support is filtered on its way to the reservoir (82). 10. blood oxygenator according to claim 9, that the filter (80) is designed as a filter tube which hangs down from the support (78) and which is a filter fabric from a polymer carries. The patent attorney Dr. ψ Gudel i / 030029/0891