NL8000200A - OXYGEN GENERATOR. - Google Patents

Description

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Applicant: Baxter Travend Laboratories, Inc., Deerfield, Illinois United States of America.

Short designation: Oxygen generator.

The invention relates to an oxygen generator for administering oxygen to and regulating the temperature of blood that flows outside the body during a surgical procedure.

Flowing blood outside the body has been a routine practice for several years in performing operations 10 and the like. An important part of the circuit for the diversion of blood outside the body is the oxygen generator for the blood. The function of the oxygen generator is to transfer oxygen into the venous blood, so that the oxygen reacts with the hemoglobin with the resultant absorption of the oxygen and the release of carbon dioxide. A historical overview of blood oxygen generators is provided in the article "Theme and Variations of Blood Oxygenators" by R.A. DeWall et al in Surgery, December 1961.

Three principal types of blood oxygen generators are known. In the oxygen generator equipped with a membrane, a semipermeable membrane separates the blood from the oxygen and gas exchange takes place by diffusion through the membrane.

One type of such an oxygen generator is described in U.S. Patent 3,413,095.

In the film oxygen generator, a thin blood film is exposed to an oxygen atmosphere. One such type of oxygen generator is described in "The Lancet," December 15,1956, p. 1246, in the article "Design of an Artificial Lung Using Polyvinyl Formal Sponge".

The bubble oxygen generator brings bubbles of oxygen directly into the blood. In such a bubble oxygen generator described in U.S. Patent 3,578,411, the bubble chamber has a continuous wound path for promoting the intermixing of the blood and oxygen. U.S. Pat. No. 3,807,958 discloses a bubble-35 oxygen generator using an 800 0 2 00 V * *

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number of vertical tubes through which the mixture of blood and oxygen moves up. US patent 3,898,045 discloses a bubble oxygen generator comprising a slatted chamber in which spherical beads are tightly packed and intended to improve gas exchange. Furthermore, the article "Preliminary Studies on the Sponge-Oxygenator" by Adriano Bencini et al, published in "Surgery" of August 1957, describes a bubble oxygen generator, in which a long multi-perforated needle is arranged in a cylindrical piece sponge made of polyurethane 10,

In the construction of U.S. Patent 4,067,696, an upward flow of a mixture of blood and oxygen moves through a three-dimensional open cell material intended to assist in the gas exchange on the hemoglobin.

For a better understanding of the present invention, koaweg can be said that the invention relates to a bubble oxygen generator which is intended for use in an out-of-body blood circuit in which oxygen bubbles are delivered to the blood to effect foaming thereof 20, while the foaming blood is distributed on a heat exchanger from where it moves downwards under gravity and to a defoaming device. Carbon dioxide is vented upward from the defoamer and the liquid blood thereof flows down under gravity into a venous blood reservoir.

It is therefore an object of the invention to provide a bubble oxygen generator which has a high / beneficial effect and offers significant clinical benefits as well as efficiency in use in a pre-sterilized low cost disposable unit.

It is a further object to obtain a bubble oxygen generator which has a relatively hard shell, so that the generator will retain its structural shape with good appearance, while economical production methods can be used using injection molding synthetic polymeric composite 35 materials.

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It is a further object to obtain a blood oxygen generator which is economical so that it can be discarded after use in order to eliminate the need for cleaning after use and to avoid the possibility of contamination as well as eliminate the cost of cleaning a unit .

It is a further object of the invention to provide a factory-made blood oxygen generator, where assembly can be accomplished with suitable molds and fixtures to achieve quality control in a "clean room" where the oxygen generator can be assembled and may be pre-sterilized later to be ready for use, overcoming the clinical and economic problems of attempting to clean an oxygen generator.

The invention will be explained in more detail below with reference to an exemplary embodiment of an oxygen generator according to the invention shown in the accompanying figures.

Fig. 1 shows a top view of an exemplary embodiment of an oxygen generator according to the invention.

FIG. 2 shows on a smaller scale perspective the manner in which the oxygen generator is arranged and connected to a system.

Fig. 3 is a perspective view of the oxygen generator shown in FIG. 2 mounted on a blank.

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Fig. 4 is a sectional view of FIG. 1, taken along line 4-4-4 in FIG. 1, with certain parts omitted for clarification of the figure.

Fig. 5 shows partly in elevation and partly in section a part of FIG. 4, seen along line 5-5 in FIG. 4.

Fig. 6 is a larger-scale perspective view of part of a support clamp.

Figures 1-4 show a preferred embodiment of an oxygen generator 10 according to the invention. The oxygen generator 10 is manufactured as a permanently assembled inexpensive disposable unit, which is at least substantially made of injection molded parts to provide a relatively rigid construction.

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which can be sterilized beforehand. The use of injection-molded parts permits the manufacture of high-quality reliable parts, which can be cheaply produced and assembled, while still providing cleanliness and reproducibility, which is important in such a construction.

When studying the oxygen generator 10 with regard to its constructional and functional details, it will look in the direction of blood flow through the oxygen generator during use.

A venous blood inlet connection 12 is directed downward. This makes it possible to suspend the venous blood connection tube 14 (fig. 2), which is directly connected to a vein channel in the patient, making it impossible for gas bubbles to escape from the oxygen generator and flow back into the patient.

A side fitting 16 also forms an inlet fitting and is for connecting a tube 18 of a cardiotomy reservoir if such a reservoir is used. If such a reservoir is not used, the tube 18 is clamped.

A sample port 19 is connected to the connector 12 by means of a conduit 21 for obtaining a sample of the venous blood. A Luer opening is provided for the sample syringe.

A flushing assembly 20 shown in cross-section in Fig. 4 comprises a cylindrical tubular body in which a flushing tube 22 is arranged. An outer cylindrical tubular space surrounding the flushing tube is open to receive oxygen from an oxygen port 24. The interior of the flushing tube 22 is approximately the internal diameter of the venous blood inlet 12.

The flushing tube 22 is a porous flushing tube. The porosity of the flushing tube 22 is critical because it determines the size of the bubbles released. A porosity on the order of 90 "Tegraglas" as manufactured by the 3M Company of Minneapolis, Minnesota is suitable, although other similar structures may use worker. If the oxygen bubbles are too small, 80 0 0 2 00 • 1 ♦ * -

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oxygen is introduced into the blood, but no carbon dioxide is removed. If the bubbles are too large, the opposite occurs, because oxygen dioxide is removed, but the oxygen supply is insufficient. With the indicated porosity, a less than 1: 1 gas to blood flow ratio produces the correct bubble size. A smaller oxygen flow produces small bubbles and more oxygen supply and vice versa.

The tubular form of the flushing tube ensures that the entire volume of oxygen is evenly mixed with blood in a non-traumatic manner. As the oxygen bubbles flow into the blood, the blood is practically forced up over the inner surface of the flushing tube.

Flushing tube 22 can be made of or covered with hydrophobic material. This will prevent outward flow of blood through the tube if the oxygen supply were to suffer a pressure loss.

Furthermore, a cover may be provided on the outside of the flushing tube 22, which serves as an anti-bacteria filter for filtering oxygen debris particles larger than 0.2 micron. The cover is a paeta layer which dries to a porous surface.

Part of the introduction of oxygen and consequent removal of carbon dioxide takes place in the initial bubble phase, as the blood foams in the flush tube 22 and the foaming mass moves upward. The blood with the oxygen bubbles entrained (starting with oxygen-CO exchange) moves upwards, driven by the gas flow, buoyancy and by inflow of venous blood.

A manifold 26 guides the upwardly flowing foaming blood into the top of a dome 28 of the main body 30 of the oxygen generator 10. The dome forms part of a lid of the lower part of the body. Within the dome 28, a flat distribution plate 32 receives the foaming blood. The foaming blood moves horizontally forward over the distribution plate 32. If the blood foam flows over the flat distribution plate 32, it is visible because the cover of the dome 35 is transparent. Thus, it is easy to inspect the blood to observe that it turns bright red compared to the dark red venous blood at the inlet, because the blood gets more oxygen.

Should the inflow of venous blood be uneven, for example due to a suction that is too high, waves of foam moving over the flat distribution plate 32 can be observed. This serves as a good indication to the operator, which will then reduce the inflow rate.

The path over which the blood foam travels is tortuous, ensuring total mixing and gas exchange. This makes it possible to use small amounts of oxygen per volume of blood. Too low an oxygen-to-blood ratio means less agitation of the blood and thus less trauma to the blood cells.

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The lower oxygen ratio also produces less foaming, so that less defoaming is required, while also reducing the oxygen cost.

The planar distribution plate 32 is spaced about 1/4 inch from the exterior of the dome 28 and thus the foaming blood is distributed along the edges where it moves downward on the perforated distribution plate 34 under the influence of gravity. flowspace 36 around the edge of the flat distribution plate 32 allows the blood foam to flow downward without allowing a large gas bubble build-up. Perforations 38 can be formed by circular holes or slots. The slots can be angled radially or at an angle or otherwise distributed to evenly dispense the foam as it travels down through the perforations 38. A thin saucer-shaped foam spreading layer 39 may be disposed below the distribution plate 34 and above the heat exchanger 40. The foam has open cells to allow blood to flow through it. The layer 39 may be uncovered to act as a distributor for evenly distributing the blood foam over the heat exchanger, but preferably the foam layer 39 is silicone coated. The silicone coating starts the vapor-liquid separation of the blood foam. This improves the contact of the liquid blood with the windings of the heat 800 0 2 00

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exchanger 40 to improve the efficiency of the heat exchange. This layer is not always necessary.

The heat exchanger is formed by a pair of coils wound in the form of a flat coil of a heat exchanger.

A cone 42 is inserted into the heart of the windings to prevent blood from escaping through the heart of the windings without heat exchange occurring. The windings of the heat exchanger 40 are wound in opposite coils in the two layers and are wound on a mandrel, which forms the internal opening into which the cone 42 ie is inserted. There are small spaces 44 between the turns of the heat exchanger in a layer, and since the turns are wound in opposite directions, there are inevitably also small spaces between the turns in the two layers. These spaces allow a deliberate flow of the blood foam between the turns, while the small space between them makes the heat exchange efficient.

The arrangement of the wound heat exchanger tube is horizontal. The planar arrangement provides for slow, parallel blood flow on the surface of the turns and through the gaps between the turns. This also results in less damage to the cells. The horizontal arrangement of the heat exchanger 4 is useful for manufacturing a small-sized construction and for maximizing the arterial reservoir volume. The windings may be silicone coated to promote the moist blood flow directly on the heat exchanger windings without the insulating effect of entrained gas bubbles, which form the foam.

Another design feature given by the present heat exchanger construction 30 is that the point where the heat exchanger tube enters and exits the jacket of the oxygen generator is above the blood level line at its highest point.

In this way, no complicated sealing structures are required and there is no blood loss at the pipe connection and the body. There are no tube connections within the body 30 of the oxygen generator, 800 0 2 00

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but both free ends of the heat exchanger tube are formed from the body.

As shown in Figures 1-4, the winding ends 46 and 48 are provided with downwardly directed connections. This allows the connection of a water pipe, such as pipes 50 and 52 (fig. 2), whereby the water circulation through the heat exchanger pipe is effected.

Without a connection in the tube within the jacket, there is no risk of water leakage into the blood. The downwardly directed water connections allow the water-filled heavily loaded pipes to drape naturally. Aluminum tube with an external diameter of 3/8 or ½ inch is preferable to be used as Heat Exchanger material. Such material is easily formed and sterilized, is inexpensive and has good heat exchange properties. However, other suitable materials can be used as an alternative.

A defoamer 54 is located in the interior of the body 30 below the heat exchanger 40. The flow of foaming blood, which is distributed throughout the heat exchanger winding, moves from the heat exchanger winding down onto the defoamer 54. An open cell synthetic polymer composite material, such as "Scottfoara", which is covered with silicone, is used as a defoamer . The surface effect of the silicone separates the entrained gas from the liquid blood so that the gas is moved upwards and can be vented. The outlet 56 is an opening in the lid of the cup 28 for the addition of fluids and medicaments. A slit 60 is provided at the periphery of the dome 28, where it extends downwardly around the top of the oxygen generator main body.

An outlet opening 58 is provided so that a vacuum can be applied to divert noxious gases from the oxygen generator. Some of the anastic gases used in an operating room are introduced into the blood and are discharged into the operating room along with the carbon dioxide if no other provisions are made. This could be harmful to the operating room personnel. PR are cases of staff trauma in 800 0 2 00

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operating theaters reported as a result of exposure to such anasthetic gases.

The display device 58 allows the use of negative pressure to discharge the released gases from the operating room. The dome 28 engages over the body 30 and closes against it except for the slit 60, which is a discharge opening, which allows the free escape of the spent gases to the atmosphere. This escape has been made for those cases where it is not necessary to discharge the gases from the operating room. When negative pressure is used through the connector 58, free air is drawn into the exhaust port 60, thereby preventing a drop in the pressure in the oxygen generator to below atmospheric pressure.

The dome 28 has an apron 62 depending on the dome.

The apron guides the downflowing blood foam onto the top of the defoamer 54 and simultaneously forms an outer passage through which the separated gases can escape.

Another circumferentially extending defoaming sponge body 64 is disposed in this annular opening to ensure that no blood foam reaches chamber 84 or exits the oxygen generator through the discharge port 58 or the discharge port 60.

A tray 66 supports the lower portion of the defoaming body 54 and has an outer wall 68 enclosing the sponge around its outer circumference. The tray 66 comprises a base 99 with the aid of which the tray rests on the reservoir 84 of the body 30 of the oxygen generator. Gas or blood can move between the upper and lower parts of the oxygen generator 10. A filter section 72 is part of the tray and has a conical or cylindrical construction 72 with a bottom 74. The interior of the filter section is open to the space above the tray 66 and may contain a defoaming body 76. A filter 80 is formed by a woven filter, which has little resistance to the flow of blood moving from the defoaming body 54 downwardly into the interior of the filter section 72.

Alternatively, the filter may have a shaped homogeneous porous structure. It from the filter section 72 through the filter 80 to the outside 80 0 0 2 00

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flowing blood is thus subjected to a final filtering action here. The filter is preferably a woven fabric made of blood-compatible synthetic polymer composite material with a preferred porosity between 100 and 250 microns. The filter material is wettable with blood, so that when wetted with blood prevents gaseous bubbles from moving through it.

Here, therefore, a final separation of gas and blood is effected, the gas being retained on the inside of the filter section 72. Despite this retaining the gas, the top 10 of the arterial reservoir 82 is also open for discharge of gas through an opening between the fitting of the saucer 66 on the shoulder 70 using the foot 99.

The arterial reservoir 82 has an increased volume at the top obtained by shoulders 108 and 84 and a small volume at the bottom obtained by a tapered body 86 of the reservoir. This shape provides more solution at the bottom end with greater storage capacity at the top. The upper end suddenly widens at the shoulder 84, but this is at a level normally above the usual blood level. Thus, if sudden reservoir capacity is required, it is available in a manner that takes up little vertical space.

Further space is present in shoulder 84 until the reservoir overflows through the discharge opening 60. *

An outlet bag 88 is formed on the bottom of the tapered body 86 of the reservoir. Outlet fittings 90 and 92 are provided for connection to outlet tubes 94 and 96. The arterial outlet fitting 92 and the arterial conduit 96 connected thereto supply blood to the arterial pump and so to the patient.

The arterial fitting 90 and the tube 94 connected thereto 50 serve as a coronary outlet.

An anti-vortex plate is positioned above the outlet 88 to prevent vortex formation. Blood flow is unimpeded around the edges of the plate. The vortex plate makes it possible to draw the blood level significantly lower into the reservoir 82 without introducing air into the outlet line through the vortex formation.

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The outlet fittings 90 and 92 face downward so that the outflow occurs straight down. This allows the arterial tubes to naturally bend from the reservoir without kinking. Sample port 110 has a Luer 5 opening for taking arterial blood samples. The sample is taken through a tube placed within the filter 80 and near the bottom of reservoir 82. When air is injected through the sample port 110, the bubbles remain within the filter 80 so that they do not move into the main arterial blood reservoir.

During use in an operating room, the heart-lung pump console generally has a vertical support rod 100. A clamp 102 carries an open metal loop 104. The loop 104 fits under shoulder 70 of the body 30. The loop 104 is rotatable about a pin 105 so that the oxygen generator can be rotated to any suitable position.

The open slit makes it possible to remove the oxygen generator while the hoses or tubes are still attached to it, so that it is not necessary to remove or cut off these hoses or tubes before that. This makes removal and cleaning more efficient, while the operator can still rotate the oxygen generator to the desired position. The oxygen generator 10 is thus easy to use.

The shape of the oxygen generator is such that, when in use, it can be positioned close to the floor, so that the blood therein can be easily drained. A small fill volume is required so that the biological fill fluid or blood used for filling prior to surgery has a small volume, resulting in less cost, weight and less material contamination. Dynamic hold-up is reduced to produce a quick response.

A pushed-through portion 97 of the reservoir supports the filter construction and can incorporate a sensor for sensing temperature into the arterial reservoir.

Although a preferred embodiment of the invention has been described, it will be understood that numerous additions and / or modifications may be made to it within the spirit and scope of the invention.

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Claims (10)

1. Blood oxygen generator having an at least substantially rigid housing and deflation means carried by the housing comprising a venous blood inlet passage, an oxygen inlet passage and a porous flushing means associated with the blood and oxygen inlet passage to provide a flow of vein bubbles in the venous blood to form venous blood foam, a passageway for the blood foam extending between the blood foaming agents and an upper part of the housing and a heat exchanger incorporated in the housing under the upper part for controlling of the temperature of the blood foam and a passage is provided for delivering blood foam to the heat exchanger, and a defoamer is further incorporated in the housing under the heat exchanger, which defoamer receives the blood foam from the heat exchanger under the influence of gravity flow to separate 15 fluid blood and gas for defoaming the blood and further an arterial venous blood reservoir is provided, bounded by the body below the defoamer for collecting liquid blood, which moves away from the defoamer under the force of gravity. Oxygen generator according to claim 1, characterized in that the flushing member is made of hydrophobic material and is at least substantially tubular, with the venous blood inlet passage extending through it. Oxygen generator according to claim 1 or 2, characterized in that the oxygen generator is further provided with an oxygen filter on the exterior of the flushing means for filtering the oxygen moving therethrough. Oxygen generator according to any one of the preceding claims, characterized in that the heat exchanger is arranged horizontally and spans substantially the flow path of the blood foam between the blood foam passage and the defoamer. Oxygen generator according to any one of the preceding claims, characterized in that the heat exchanger is provided with a flat wound tubular coil. Oxygen generator according to any one of the preceding claims, characterized in that 800 02 00 - 13 - 21800 / CV / lU, that distributing means are arranged above the heat exchanger for receiving the venous blood foam from the passage for this venous blood foam and distributing the blood foam over the heat exchanger, the distribution means comprising an at least substantially flat unperforated distribution plate near the passage for the blood foam and a perforated distribution plate located below, the perforated plate being provided with perforation above the heat exchanger deliver blood foam evenly to the heat exchanger. Oxygen generator according to any one of the preceding claims, characterized in that the heat exchanger is provided with a through tube, the ends of which extend through the housing above the level of the blood foam in the housing. Oxygen generator according to any one of the preceding claims, characterized in that the oxygen generator is provided with an internal funnel-shaped support member, which is carried in the housing under the heat exchanger, this member supporting the defoaming member near its top end and tapering in the direction of its bottom end for conducting blood into the reservoir. Oxygen generator according to claim 8, characterized in that a filter member is carried at the lower end of the support member for filtering blood coming out of the support member during the movement of ha: blood in the reservoir. Oxygen generator according to claim 9, characterized in that the filter member is provided with a tubular frame, which depends on the support element and carries a synthetic polymer filter fabric. 800 0 2 00