US 3142296 A
Description (OCR text may contain errors)
Julyzs, 1964 J. w. LOVE.
, BLOOD OXYGENATORII.
Filed May 31, 1962 linen r01? flm M Mm irrakme vs,
United States Patent 3,142,296 BLUGD OXYGENATOR Jack W. Love, 38 Faculty Lane, University City, Mo. Filed May 31, 1962, Ser. No. 198,815 6 (Iiaims. (Cl. 128-214) This invention relates to extracorporeal blood oxygena .tion.
The subject of apparatus and methods for oxygenating blood has been well summarized in a two-part article entitled Theme and Variations on Blood Oxygenators which appeared in Surgery in December 1961 (vol. 50, No. 6, pages 931 et seq.), and February 1962 (vol. 51, No. 2, pages 251 et seq.).
In some of the prior art devices illustrated in this article, domed vessels have been used for various purposes, positive displacement pumps are shown, and though the use of the arrangement is not indicated, the piping is such as to permit shunting of the blood (cf. 50:6, page 932, Jacobi, FIG. 4, page 935, Issekutz, FIG. 9, page 936, Euler and Heymans, FIG. but these devices were characterized by complication, the production of froth, or considerable violence to the blood.
One of the objects of this invention is to provide apparatus and method, for oxygenating blood, which are simple, safe, inexpensive, gentle and effective.
Another object is to provide such apparatus which requires so little priming as to permit the use of saline solution rather than blood to prime.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.
In accordance with this invention, generally stated, oxygen-poor (venous) blood is oxygenated by filming it gently on the underside of a dome of a container which is swept by oxygen-rich gas. Preferably, a part of the oxygenated (arterial) blood is recirculated with additional venous blood, through the oxygenating container. The carbon dioxide released in the container from the venous blood is swept out with excess oxygen-rich gas. The system is closed, which makes for sterility, and the gentle filming, along with the construction of the closed system, substantially eliminates frothing of the blood, minimizes the danger of embolism, and produces relatively little damage to the elements of the blood as compared with the apparatus and method of Euler and Heymans, supra, or Hooker (Surgery 51:2, page 252, FIG. 3), for example.
The construction of the apparatus and simplicity of the method make it possible easily to provide for heating or cooling of the extracorporeal blood, its oxygenation or degasification under reduced or augmented pressures, the addition of drugs or other materials, or for other variations on the simple oxygenation of the blood.
The preferred form of apparatus of this invention is a sphere with a blood reservoir at the bottom, resembling an inverted Florence flask. While its theory forms no part of this invention, it is considered that the stretching and contracting of the film first as it approaches the horizontal diameter, and then as it approaches the reservoir causes a gentle but elfective tumbling or turbulence of the blood and its red cells, which makes the apparatus particularly effective. As has been indicated in the objects, a result of this effectiveness, both in the oxygenation, and in the non-frothing aspect, is that the apparatus can be made relatively small, and the reservoir of blood can be small, so that little priming is necessary, and, even with recirculation, the loss of the blood to the subject during the bloods extracorporeal circulation, is not untoward.
In the drawing, FIGURE 1 is a sectional view along the longitudinal axis of one embodiment of aerating container of this invention; with certain appurtenances shown somewhat diagrammatically;
FIGURE 2 is a diagrammatic view of one embodiment of apparatus of this invention; and
FIGURE 3 is a diagrammatic view of another embodiment of apparatus of this invention.
Referring now to the drawing for an illustrative embodiment of apparatus of this invention, reference numeral 1 indicates an oxygenating container, spherical except for a cylindrical reservoir 2 at its lower end.
A venous blood conduit 3 extends through the reservoir 2, and diametrically into, and through substantially the full height of the container 1, terminating with an outlet 4 positioned adjacent the underside of the uppermost point of the dome of the container, in filming relation thereto. A conical drip shield 6 is secured to and around the outside of and near the upper end of the conduit 3.
Concentric with and spaced radially outwardly from the venous blood conduit 3 is a gas outlet tube 10, open at its upper end to form an inlet 11, and sealed at its lower end, below the blood reservoir 2, around the venous blood conduit. Near its lower end, below the reservoir 2, the tube 10 communicates with a waste gas outlet tube, which may be vented to the atmosphere, or, if super or sub-atmospheric pressure is indicated in the container 1, to a pressure valve or vacuum source, as the case requires. In the embodiment illustrated, it is vented to the atmosphere.
In the embodiment shown, the inlet 11 of the tube 10 is positioned near the horizontal diametric plane of the container 1. As is clearly shown in FIGURE 1, the tube 10 is sufficiently spaced from the conduit 3 to leave a clear passageway 12 between them.
An oxygen admitting tube 20 surrounds and is concentric with the gas outlet tube 10, and is spaced radially from it to provide a passage 21 between them. The oxygen admitting tube 20 ends, at its upper end, with an open outlet 22, positioned substantially below the waste gas inlet 11. At its lower end, below the reservoir 2, the oxygen tube 20 is sealed to and around the Waste gas outlet tube 10, and, below the reservoir 2, it communicates with an oxygen pipe 24, which, in turn, communicates with a source of oxygen-rich gas 26. An oxygen-rich gas deflection shield 25 is secured to and around the tube 10 above the open outlet 22 at a distance such as not to impede the flow of gas from the outlet 22 but to tend to deflect its course radially outwardly.
An arterialized blood conduit 30, which communicates with the bottom of the reservoir 2, completes the fittings of the oxygenating container. I 7
Outside of the container 1 and its fittings, the system of this invention includes a venous blood supply line 40, an arterial blood return line 50 connected to the arterialized blood conduit 30, a shunt line 54, with a valve 55 in it and a blood pump 45, which may be a standard DeBakey roller pump, connected in the venous blood line 40, to pump blood from a subject 100 and into the venous blood conduit 3, and also connected in the return line 50, to pump arterial blood from the reservoir 2 and into the subject 100. The valve 55 may be a simple cock or clamp, or it may be a check valve permitting flow only toward the venous supply line 40, or it may I be an adjustable pressure-responsive valve, and is preferably the latter. A flow meter 56 is also in line 54. i
The venous blood supply line 40 is connected, inuse, to a vein of the subject the arterial blood return line 50, to an artery. The operation of the simple device illustrated in FIG- URE 2, will be illustrated in terms of actual laboratory use with dogs. This is, of course, merely by way of illustration, and is not to be considered limitative.
For a 20 kilogram female dog, upon which an operation was to be performed, a 12 inch diameter globe was used, primed with 500 milliliters of saline solution. The venous blood conduit 3 had an internal diameter of approximately inch, and was cut off squarely. The outlet 4 was positioned approximately inch from the inside surface of the axial center of the dome.
The venous blood line 40 was connected to the superior and inferior venae cavae of the animal and the arterial blood return line 50 was connected to the animals left femoral artery. The valves 41 and 51 were closed and the valve 55 opened. The pump 45 was started and regulated to deliver 4 liters per minute of flow as indicated by the flowmeter 56. The saline solution was circulated through the shunt line 54, venous blood line 40, venous blood conduit 3, arterialized blood conduit 30 and arterial blood return line 50, filming on the inside surface of the dome, wetting the container wall and preparing the system for the reception of the animals blood. The sweep of oxygen-rich gas through the container was then begun. In this instance, pure oxygen was supplied to the interior of the globe at the rate of 4 liters per minute, and exhaust gases were vented to the atmosphere. The pressure in the interior of the container 1 was less than 14 pounds p.s.i.g. The valves 41 and 51 were then opened and the shunt valve 55 adjusted so as to supply blood or, initially, a mixture of blood and saline solution, to the animal, and to remove blood from the animal at the rate of about 1 liter per minute. In this way, in a relatively short time after the extracorporeal circulation was begun, most of the blood was recirculated through the oxygenating container about three times before its return to the animal.
In a series of tests, the simple apparatus shown and described has been used for periods of total cardiopulmonary by-pass during operations on dogs, varying in length from 5 to 70 minutes, with no operative mortality attributable to the design and function of the apparatus.
It can be seen that with different animals, including human beings, it may be necessary or desirable to change the rate of flow of gas or blood or both, the size of the container, and the composition, volume and perhaps pressure of the oxygen-rich gas. These changes, in turn, may require different dimensions of the various tubes and conduits, but these are mechanical adjustments which will be readily understood by those skilled in the art.
In FIGURE 3, a system is shown, in highly diagrammatic form, which incorporates several attachments to or variations in the simple system shown in FIGURE 2. In the venous blood supply line 40, between the shunt line 54 and the pump 45 there is shown a reservoir 70, connected with the venous blood line 40 by a line 71 in which is a valve 72. The reservoir 70 has been used as a coronary sinus reservoir for coronary blood collected by suction. Drugs, saline solution, nutrients, or the like, can also be introduced to the blood stream from the reservoir 70. Several such reservoirs or their equivalents can be provided, if desired.
In FIGURE 3, the oxygenating container 1 is shown as being used as a heat-exchanger also. This has been found to be an excellent arrangement. The container may be provided with a jacket 80, as shown, with thermal fluid inlet and outlet pipes 84 and 85, connected to suitable sources of warm or cold fluid and drain or return lines, respectively. Alternatively, thermal fluid, e.g. warm or cold water, may simply be flowed over the outer surface of the container, or coils can be provided around it, or it can be positioned in an open bath. Since the blood is filmed, the heat transfer between the thermal fluid and blood has been found to be quite efficient. It may be found desirable, from the gas exchange point of view, or to minimize damage to the blood, to both cool and heat the blood, at different stages. To these ends, a
4 separate heat exchanger may be provided in the line 40 or 50 or both.
A pressure equalization tank is also shown. The tank 90 can be used either in conjunction with the heating and cooling system, or, if the blood is aerated at super or sub-atmospheric pressures, it can serve as a safety device to ensure that the blood immediately before it is pumped back to the body is at atmospheric pressure. Super-atmospheric pressure can be had by putting a valve on the excess gas outlet and thus restricting the escape of gas, permitting the pressure to build up toward the pressure of the source of oxygen-rich gas. Sub-atmospheric pressure can be had by attaching a vacuum pump to the excess gas outlet, and putting a restricting valve in the oxygen rich gas inlet 24. The blood is preferably pumped out, into a tank such as tank 90, by a pump synchronized with the pump 45, or by the pump 45 itself, if the tubing can be so arranged.
The provision of the shunt line and valving providing a variable resistance to flow through the shunt, has been found to be a great importance. With a pressure differential type valve in the shunt line, responsive to either a build-up of pressure in the arterial blood return line 50 or a drop in pressure in the venous blood supply line 40, there is partically no danger of producing a dangerously high pressure on the arterial side or dangerously low pressure on the venous side. The pressure on the venous side is normally practically atmospheric.
The flowmeter 56 is preferably provided with one inverted scale. By positioning the flowmeter in the shunt line, the operation of the pump 45 can be checked at the onset, and the rate of flow regulated. The pump can then be left at one setting, since it receives and delivers exactly the same amount of liquid, and the perfusion rate is governed by varying the resistance in the shunt line. While it is conceivable that the shunt line might be blocked, this is highly improbable, because there is always a substantial flow through it. For safety, an attachment to the differential valve can be used to shut off the pump 45, but, unlike most present commercial aerators, a temporary blockage will not shut down the entire machine. The presence of a blockage in the subject on either the venous or arterial side will be signaled immediately by the flowmeter, because the flow through the shunt line will increase.
This will appear as a decrease on the inverted scale, which will read the difference between the total flow and the flow through the shunt line, which must be the perfusion rate.
For some reason, believed to be related to the substantial absence of priming blood and to the gentleness of the system, it has been found that pure oxygen can be used satisfactorily as the oxygen-rich gas in the operation of the system with laboratory dogs. However, the usual oxygen-carbon dioxide mixture may be found desirable in other circumstances, or different mixtures of gases, but they do not form a part of this invention.
Numerous variations in the construction and operation of the apparatus and method of this invention respectively, within the scope of the appended claims, will occur to those skilled in the art in the light of the foregoing disclosure. For example, the container is preferably made of glass or transparent or translucent plastic, so that the filming and oxygenating of the blood can be checked visually, but other materials may be used. Similarly, the piping can be made of various different materials. Different forms of pumps are operative. Valves of various sorts may be employed in the system. While the spherical type domed container is preferred, an inverted pear-shaped, ovoid, acorn-shaped or even conedomed container may be used, if the blood can be filmed gently from a central point, substantially circularly. The volume of recirculating blood can be altered both in absolute amounts and relative to the circulation of fresh blood, and various amounts and mixtures of oxygenrich gases can be used. These are merely illustrative.
Of course, a plurality of oxygenating containers may be employed, in series or parallel, but the greatly increased surface area obtained with an increase in diameter of a spherical container makes it possible to accommodate and oxygenate a large volume of blood with relatively little increase in size of a single oxygenating container, so that a plurality of containers need not ordinarily be employed.
Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:
1. Apparatus for oxygenation of blood, comprising a stationary, light permeable container having a dome; venous blood conduit means extending within, and directed upwardly toward the upper inner surface of the dome of said container, and outlet for said conduit opening upwardly at the upper inner surface of the dome of said container and spaced therefrom an amount whereby a flowing stream containing blood at discharge velocity from said outlet can produce a gentle filming on the inner surface of said dome from a central point of the stream substantially circularly over the inner dome surface; an arterialized blood conduit means communicating with a part of said container lower than said dome, in which blood accumulates; an oxygen admit-ting tube above said part of the container and below the venous blood conduit outlet; a gas outlet, and pump means for forcing blood through said venous blood conduit means and for removing an equal volume of arterialized blood from said container through said arterialized blood conduit means.
2. The apparatus of claim 1, wherein shunt means are provided, interconnecting the venous blood conduit means and the arterialized blood conduit means, whereby arterialized blood is recirculated through said venous blood conduit means, and metering means operatively connected to said shunt means for regulating the perfusion rate of the apparatus while maintaining the pump output constant.
3. The apparatus of claim 1 wherein thermal liquid means are provided for bathing at least a portion of the exterior surface of the blood-filming wall of the container in thermal liquid at a controlled temperature diflerent from the ambient temperature of the space in which the apparatus is.
4. The combination as defined in claim 1 in which said pump means have equal flow rates and a shunt line having a variable restriction connects the output side of one of said pump means with the input side of the other pump means, whereby the volume of liquid withdrawn from, and introduced into the subject remains constant for a given setting of said restriction.
5. Apparatus for oxygenating fluent blood comprising a hemispherically domed light permeable container, the dome being uppermost, and, in order of height of opening and radial distance from the center, a venous blood conduit means extending within, and directed upwardly toward the upper inner surface of the dome of said container, an outlet for said conduit opening upwardly at the upper inner surface of the dome of said container and spaced therefrom an amount whereby a flowing stream containing blood at discharge velocity from said outlet can produce a gentle filming on the inner surface of said dome from a central point of the stream substantially circularly over the inner dome surface, a gas venting tube concentrically arranged about said venous blood conduit and having an outlet concentric with the opening of the venous blood conduit, and an oxygen admitting tube concentrically arranged about said gas venting tube, and having an outlet concentric with the gas venting tube outlet, the outlets of the gas venting and oxygen admitting tubes being oflset vertically from one another and from the venous blood conduit opening, with the gas venting tube outlet intermediate the other two.
6. Apparatus for oxygenation of blood, comprising an oxygenating container having a dome, venous blood conduit means leading to and extending within said container, said venous blood conduit means including a tube extending within and directed upwardly toward the upper surface of the dome of said container and provided with an outlet opening upwardly at the upper inner surface of the dome of said container, spaced therefrom an amount whereby a flowing stream containing blood at discharge velocity from said outlet can produce a gentle filming on the inner surface of said dome, from a central point of the stream substantially circularly over the inner dome surface, arterialized blood conduit means leading from said container, pump means in the venous blood and arterialized blood conduit means arranged to pump an equal flow rate of liquid through both said conduit means, a shunt line connected between the venous blood conduit and arterialized blood conduit means on the suction side of the pump means in the venous blood conduit means and the discharge side of the pump means in the arterialized blood conduit means whereby the blood is recirculated without build up of pressure in said arterialized blood conduit means, and variable resistance means in the shunt line, whereby with a constant output of said pump means, a variable flow of blood through the shunt line can be effected.
References Cited in the file of this patent UNITED STATES PATENTS 2,659,368 Gibbon et al Nov. 17, 1953 2,760,922 Williams Aug. 28, 1956 2,827,901 Jones Mar. 25, 1958 2,896,620 Tremblay July 28, 1959 2,927,582 Berkman et al. Mar. 8, 1960 3,017,885 Robicsek Ian. 23, 1962 OTHER REFERENCES Dickson et al.: A System for Ven-Arterial Pumping, Surgery, vol. 45, No. 2, February 1959, pages 288-291.