Integral Blood Oxygenator And Heat Exchanger

Abstract

An integral blood oxygenator and blood temperature controller combination concurrently provides blood oxygenation at a precise blood-gas temperature required by a patient. The integral combination operationally insures that the extra-corporeal circulating blood is equilibrated with oxygen gas at a patient's required blood temperature. Multiple, small diameter aperture, equal length oxygen exchange tubes are adjacently spaced in a patterned, parallel array and secured at the pairs of tube terminus in an opposed pair of tube header plates, forming a blood-gas-energy exchange tube array. The two-phase blood-oxygen-gas mixture flows upward inside each of the single oxygen exchange tubes, absorbing oxygen and evolving carbon dioxide gas. Precisely temperature controlled water circulates through the gas exchange tube array around the exterior of the oxygen exchange tubes, providing precise blood temperature control during oxygenation process. By equilibrating oxygen consumption and carbon dioxide evolution at a precise blood temperature, undesired gas bubble evolution at higher random blood temperature excursions are minimized, lowering the potentiality of gas bubble evolution and gas embolism.

Description

CROSS REFERENCES TO RELATED APPLICATIONS

This application is related to the following applications filed earlier by the sole inventor, Robert C. Brumfield:

U.S. patent application, Ser. No. 175,182 for BLOOD OXYGENATOR AND THERMOREGULATOR APPARATUS, by Robert C. Brumfield, filed Aug. 26, 1971;

U.S. patent application, Ser. No. 196,458 for BLOOD OXYGENATOR FLOW GUIDE, by Robert C. Brumfield, filed Nov. 11, 1971;

U.S. patent application, Ser. No. 202,779 for TWO-PHASE FLUID FLOW GUIDE FOR BLOOD OXYGENATOR, by Robert C. Brumfield, filed Nov. 29, 1971; and

U.S. patent application, Ser. No. 216,649 for LOW PRESSURE HEAT EXCHANGER FOR OXYGENATED BLOOD, by Robert C. Brumfield, filed Jan. 10, 1972.

BACKGROUND OF THE INVENTION

Blood oxygenators and blood temperature controllers useful for oxygenating patient's blood in extra-corporeal circulation are classified in Class 23 Subclass 258.5. The improvement taught in this invention is likewise so classified.

Fuson, in U.S. Pat. No. 3,064,649, issued Nov. 20, 1962, discloses a blood filter and a separate heat exchanger apparatus for use with extra-corporeal blood circulating apparatus. A mechanically separate heat exchanger and blood filter are serially connected. The heat exchanger is taught for the induction of hypothermia, a conventional separate oxygenator being disclosed in the specification.

DeWall in U.S. Pat. No. 3,256,883, issued June 21, 1966, discloses a two dimensional envelope or bag-type oxygenator comprised in large part of thermoplastic resinous sheet material sealed together. The temperature control or heat exchanger means shown is in the form of a channeled internal water jacket, which is heat sealed between walls of the oxygenator in the vicinity of multiple blood channels or conduits, warming or cooling the blood as it passes through those channels. Specifically, this invention teaches the first step of oxygenating the blood at a relatively uncontrolled blood temperature, and then effectively controlling the blood temperature in a second step by circulating the blood through a heat exchanger.

Claff et al in U.S. Pat. No. 3,332,746, issued July 25, 1967, discloses a pulsatile membrane apparatus for oxygenating blood, disclosing a separate heat exchange fluid source which circulates through the oxygenator. Grooved metal plates in combination with the externally pumped heat exchange fluid provide a heat transfer energy input or output source for the blood circulating in the oxygenator. The oxygenation of the blood proceeds by diffusion through a suitable membrane.

Farrant, in U.S. Pat. No. 3,374,066, issued Mar. 19, 1968, teaches a separately disposed thermostabilizer for an extra-corporeal oxygenator of blood. A separate conventional blood oxygenator system is disclosed providing for the oxygenation of the blood, and a heat exchanger is taught for the thermostabilization of the blood temperature.

The subject invention teaches an integral blood oxygenator and heat exchanger improvement providing blood oxygenation at a precise blood-gas-temperature required by the patient. By concurrently equilibrating the oxygen consumption and the carbon dioxide gas evolution at a required precise blood temperature, undesirable gas bubble evolution resulting from lowered gas solubility at higher random blood temperature excursions are minimized, lowering the potentiality of gas embolism.

SUMMARY OF THE INVENTION

The integral blood oxygenator and heat exchanger combination operationally insures that the extra-corporeal blood is equilibrated with oxygen gas at a patient's required blood temperature. Multiple, small diameter oxygenator tubes having equal tubular lengths, are disposed in a patterned parallel array, having a tubular array base terminus and a tubular array top terminus. A base header plate secures the patterned array of oxygenator tubes at the array base terminus providing a fluid-impervious base plate terminus for the tube array. A top header plate secures the patterned array of oxygenator tubes at the array top terminus, providing a fluid-impervious top plate terminus for the array of tubes. A tubular boundary case secures the base header plate, the top header plate and the multiple oxygenator tubes in a tube exchanger configuration. One heat transfer fluid conduit is conductively secured to the boundary case adjacent to the base header plate. A second heat transfer fluid conduit is secured to the boundary case, and conducts heat transfer fluid adjacent to the top header plate. A two-phase blood-oxygen-gas mixture circulates upwardly inside the multiple oxygenator tubes and a precisely temperature controlled heat transfer fluid circulates exteriorly to the oxygenator tubes inside the tube exchanger configuration. The second heat transfer fluid conduit is conductively secured to the boundary case, disposed to conduct heat transfer fluid in the interior of the case adjacent to the top header plate. The two-phase blood-oxygen flow in the oxygenator can be formed with a minimum of turbulence and damage to the formed elements of the blood by providing an annular blood inlet channel orfice. An inlet blood tubular manifold has a first blood manifold terminus coaxially secured to the blood oxygenator volume boundary case. The first blood manifold terminus has a diameter not less than the external diameter of the boundary case. The blood manifold has a base plate securing the second blood manifold terminus, the plate providing a locus of a multiplicity of gas injection apertures normally disposed through the base plate. A diffusion tube is secured concentrically to the first blood manifold terminus at a first tube terminus of the diffusion tube, the blood diffusion tube having a second tube terminus disposed a spaced small interval from the base plate. The diffusion tube has an internal diameter at least equal to the base plate locus of the multiplicity of gaseous injection apertures, providing an annular blood inlet orfice. By providing a serrated second tube terminus on the blood diffusion tube, further control of the blood input is provided.

Other objects and advantages of this invention are taught in the following description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A description of this invention is to be read in conjunction with the following drawings:

FIG. 1 is an elevation perspective partial sectional view of the integral blood oxygenator and heat exchanger.

FIG. 2 is a sectional view through 2--2 of FIG. 1.

FIG. 3 is a sectional view through 3--3 of FIG. 1.

FIG. 4 is a sectional view through 4--4 of FIG. 1.

FIG. 5 is a sectional view through 5--5 of FIG. 1.

FIG. 6 is a sectional view through 6--6 of FIG. 1.

FIG. 7 is an encircling view through 7--7 of FIG. 1.

FIG. 8 is a further improvement, in a section view similar to the sectional view of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An extra-corporeal integral blood oxygenator and temperature controller 10 is shown in elevational sectional perspective view in FIG. 1, and is suitable for rapidly absorbing oxygen gas in the patient's circulating blood, replacing the carbon dioxide. Multiple oxygenator tubes 11, having equal tubular lengths 12 and small tubular diameters 13, are disposed in a patterned parallel array 14, as further illustrated in FIG. 3. The tubular array 14 has a tubular array base terminus 15 and a tubular array top terminus 16. A base header plate 17 secures the patterned tubular array 14 of oxygenator tubes 11 at the array base terminus 15, providing a fluid-impervious plate terminus for the array of tubes 14. A top header plate 18 secures the patterned array 14 of oxygenator tubes 11 at the array top terminus 16, providing a fluid-impervious plate terminus for the array of tubes 14. A tubular boundary case 19 secures the base header plate 17, the top header plate 18, and the multiple oxygenator tubes 11 in a tubular exchanger configuration 20. At least one heat transfer fluid conduit 21 is conductively secured to the boundary case 19 adjacent to the base header plate 17. At least one heat transfer fluid conduit 22 is conductively secured to the boundary case 19, disposed to conduct heat transfer fluid from the interior of the tubular boundary case 19 adjacent to the top header plate 18. At least one heat transfer fluid tube 24 is conductively secured to the heat transfer fluid manifold 23, the at least one heat transfer fluid tube 24 conductively terminating adjacent to but spaced from the top header plate 18, thus providing a conduit means for the flow 64 of heat transfer agent through the tubular exchanger configuration 20, from the heat transfer conduit 21 to the heat transfer conduit 22. Obviously the heat transfer conduit 21 can be used as the heat transfer fluid inlet, and the heat transfer conduit 22 can be used as the heat transfer conduit outlet, or vice versa; the conduit 22 can be used as an inlet and 21 as the outlet. As shown in FIG. 1 and in further detail in FIG. 7, the heat transfer fluid manifold 23 provides a conductive header fitting for the one or more heat transfer fluid tubes 24, together comprising the composite heat transfer conduit means 25.

An inlet blood tubular manifold 26 has a first blood manifold terminus 27 which is coaxially secured to the tubular boundary case 19, adjacent to the base header plate 17. As shown in FIG. 1, the blood manifold 26 fits snugly around the external diameter of the boundary case 19, the first blood manifold terminus 27 having an inside diameter 28 precisely snugly greater than the boundary case 19. The blood manifold 26 has a base plate 29 forming the second blood manifold terminus. The base plate 29 provides a locus 36 of a multiplicity of gas injection apertures 30 normally disposed through the base plate, as shown in greater detail in the cross sectional view of FIG. 2. The remainder of the blood-oxygen mixer combination is a blood diffusion tube 31 secured concentrically to the first blood manifold terminus 27 at a first tube terminus 32 of the first diffusion tube 31. The diffusion tube 31 has a second tube terminus 33 disposed a small spaced interval 34 from the base plate 29. The diffusion tube 31 has an internal diameter 35 at least equal to the locus 36 of the multiplicity of gas injection apertures 30 in the base plate 29, providing an annular blood inlet orifice 63, typically having an 0.020 inch wide spaced interval 34.

A pair of blood inlet conduits 37 are shown in FIGS. 2 and 3 in plan view, and in FIG. 1 in elevation. More than one blood inlet conduit 37 is provided in the event of an emergency stoppage of one conduit, preventing catastrophic stoppage of blood flow to the patient. The conduits are secured to the blood inlet manifold 26. An oxygen gas manifold 38 is concentrically secured to the blood manifold second terminus, adjacent to the base plate 29. An oxygen gas inlet conduit 39 is conductively secured to the gas manifold 38. Plural support ribs 40 are shown disposed in the oxygen gas storage aperture 62, providing rigidity for the manifold 38, adding structural strength to the manifold when the blood oxygenator 10 is used in a vertical standing position. FIG. 1, taken together with FIGS. 2 and 3 illustrate the blood inlet flow 41 through the pair of blood inlet conduits 37. The oxygen gas inlet flow 42 is shown introduced through the gas inlet conduit 39.

As further illustrated in FIGS. 1, 2 and 3, the blood inlet annular channel 43 is conductively filled with patient blood which flows through the annular blood inlet orifice 63 into the blood-oxygen mixing aperture 44. The oxygen stream 42 flows through the oxygen gas storage aperture 62, through the multiple gas injection apertures 30 in the base plate 29, forming in the blood-oxygen mixing aperture 44 a two-phase mixture of oxygen and blood. The two-phase mixture of blood and oxygen is earlier taught and disclosed in detail in the prior art references cited above, which are by reference made a teaching of this invention. The two-phase blood-oxygen-carbon dioxide gas mixture changing composition is lifted up through the multiple oxygenator tubes 11 of the tubular array 14, emerging at the tube array top terminus 16 as an oxygenated blood-gas foam 45. Concurrently with the oxygen absorption-carbon dioxide gas evolution exchange process which is occurring in the multiple oxygenator tubes 11, there is a heat transfer process. The oxygenated blood-gas foam 45, and its predecessor inside the oxygenator tube 11, exchanges energy with the heat transfer fluid typical flow 64 on the exterior of the tube 11 in the tubular exchanger configuration 20. The heat transfer fluid flow channel 46 vents the plural heat transfer fluid tubes 24, conducting the heat transfer fluid through the conduit 22 to the outside of the blood oxygenator 10. FIGS. 4 and 7 illustrate in detail view the configuration of the fluid conduit means 25 comprising the heat transfer fluid manifold 23 and the plural heat transfer fluid tubes 24, in relationship to the multiple oxygenator tube 11.

A blood defoaming chamber volume 47 is disposed above the tubular exchanger configuration 20. The blood-gas foam 45 venting from the oxygenator tubes 11 collapses in the volume 47, as the foam 45 contacts the defoaming sponge envelope 48 which surrounds the defoaming chamber volume 47. As taught in the prior cross references listed above, the defoaming sponge envelope is treated with a very thin film of a silicone composition which is known to collapse blood foam, without adding toxic chemical constitutents to the blood stream. The pair of collars 49, together with a pair of compression rings 50, seal the sponge envelope 48 to the case 19, thus requiring the blood-gas foam composition 45 to penetrate the envelope 48 and hence to become degassed. The degassed blood collects in the blood reservoir 65. The tubular blood reservoir case 51 has a reservoir base closure 52 secured thereto, having a pair of oxygenated blood outlets 53, shown in FIGS. 1, 4 and 5. When the blood oxygenator 10 is operated in the normally vertical upright position, the defoamed blood will collect in the blood reservoir 65 and exit through one or both of the pair of blood outlets 53, as indicated by the blood flow 54.

The tubular blood reservoir case 51 has a reservoir top closure 55 which is shown in more detail in FIG. 6. The top closure 55 has plural gas vent apertures 56 alternately disposed in the closure 55, allowing the venting of exchanged carbon dioxide gas and the excess oxygen gas, along with water vapor, from the blood oxygenator 10. The indexing pins 57 are shown molded in the reservoir top closure 55, providing securing means for centrally indexing and holding the sponge envelope 48. Apertures 59, 60 and 61 are disposed in the top closure 55, the reservoir base closure 52, and the blood manifold 26 respectively. The apertures 59, 60 and 61 are sized and shaped for acceptance of the Luer fitting of a hypodermic syringe, providing apertures for the introduction of medicament that may be required. The apertures may be closed with conventional rubber plug closures.

A further modification illustrated in FIG. 8 provides an annular blood inlet serrated orfice. As illustrated in FIG. 8, the further two-phase blood oxygen mixer combination improvement has most of the components as illustrated in FIGS. 1, 2 and 3 and a serrated diffusion tube 80. The serrated diffusion tube 80 has a first tube terminus 81 secured to a header plate 17 and a second tube terminus 82 disposed a spaced interval 83 from the base plate 29. The spaced interval 83 between the second tube terminus 82 and the base plate 29 can be that value which provides a suitable serrated annular blood inlet orfice 84 between the diffusion tube 31 and the base plate 29. The annular blood inlet orfice 84 provides an additional safety means for spreading and controlling the inlet blood flow 41. The numerical value of the annular inlet orfice serrations can be those values required width. Likewise, the spaced interval 83 can be typically 0.020 to 0.025 inches.

The structural members of the blood oxygenator and blood temperature controller 10 can be plastic tube and molded structures whose chemical compositions are physiologically compatible with blood, doing a minimum of damage to the patient's extra-corporeal blood circulation. Typically polycarbonate, polypropylene, polyethylene and selected plasticized polyvinyl chloride compositions can be utilized. Structural components such as the reservoir top closure 55, the reservoir base closure 52, the base header plate 17, the top header plate 18, the blood inlet manifold 26 and the oxygen gas manifold 38 are injection molded components. The tubular components 51, 19 and 11 can be extruded tubing. It is important for the patient's safety that the components of the blood oxygenator and temperature controller 10 be assembled and secured together by the appropriate fluid-impervious joints as are required. The components can be secured together by cementing with suitable compatible cement, by ultrasonic sealing of the chemically compatible components, or by dielectric sealing as is suitable. Specific attention must be given to the selection of chemically compatible and physically compatible plastics throughout the component assemblage, to provide for long term stability of the apparatus 10 in storage and for safety in its usage.

By utilizing the flexural rigidity of the polycarbonate plastic it is possible to fabricate a tubular exchanger configuration 20 utilizing multiple polycarbonate oxygenator tubes 11 together with the tubular boundary case 19 and a pair of header plates 17 and 18. Typically polycarbonate oxygenator tubes 11 having a tube internal diameter 13 of 0.270 inch, a wall thickness of 0.015 inch, and a 14 inch length, has a collapse pressure of 89 lbs psi. A similar polypropylene tube having 0.282 inch internal diameter, a 0.009 inch wall, and a 14 inch length has a collapse pressure of approximately 12 psi. Since the polypropylene has about 60 per cent of the thermal conductivity of the polycarbonate, the polycarbonate tubing wall of 0.015 inch thickness has the same thermal conductivity as the 0.009 inch thick polypropylene tubing wall. It is desirable to use a thicker polycarbonate oxygenator tube, insuring safety from wall collapse due to fluid pressure from a typical water heat transfer fluid which can be circulated through the tubular exchange configuration 20.

The extra-corporeal circulation of patient blood carries inherent hazards, as the loss of circulation for a few seconds can be catastrophic for the patient. The patient's blood should circulate a minimum of time outside of the patient's body and the blood should be maintained at the temperature required by the appropriate surgical procedure. By concurrently equilibrating the oxygen consumption and the carbon dioxide gas evolution at a precisely controlled blood temperature, the potentiality of saturating the blood with oxygen and carbon dioxide at a lower blood temperature than is required by the surgical procedure can be eliminated. The elimination of the excessive oxygen consumption and carbon dioxide gas evolution can further eliminate the potential for undesired gas bubble evolution at higher blood temperature excursions, resulting in bubble evolution forming a gas embolism in the patient's body. Typically by utilizing 33 oxygenator tubes 11, having internal diameters 13 of 0.270 inches, and a 14 inch length, blood flow rates up to 7,500 ml/min can be oxygenated, utilizing oxygen-blood flow ratios of typically from 1:1 to 4:1. By plugging one or more of the oxygenator tubes 11, the same oxygenator size can be utilized for oxygenating of patients ranging in size from juveniles to adults.

Many modifications and variations in the improvement in the integral blood oxygenator and heat exchanger apparatus can be made in the light of our teaching. It is therefore understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

We claim:

1. An extra-corporeal blood oxygenator and blood temperature controller suitable for exchanging oxygen for carbon dioxide in patient circulating blood, wherein the improvement combination comprises:

a multiplicity of small diameter, oxygenator tubes, disposed in an equal length patterned parallel tubular array, said tubular array ranging from 4 to 24 inches long and said tubes ranging from one-sixteenth to five-sixteenths inches in a single tube diameter, said tubular array having a base terminus and a top terminus;

a base header plate securing said patterned array of oxygenator tubes at said array base terminus, providing a fluid impervious plate terminus for said array of tubes;

a top header plate securing said patterned array of oxygenator tubes at said array top terminus, providing a fluid impervious plate terminus for said array of tubes;

a tubular boundary case securing said base header plate, said top header plate and said multiple oxygenator tubes in a tube exchanger configuration;

a pair of heat transfer fluid conduits conductively secured to said boundary case adjacent to said base header plate, one said conduit draining said boundary case adjacent to said base header plate, and the second said conduit extending inside and terminating inside said boundary case adjacent to said top header plate, draining said boundary case; and

mixing means providing two-phase blood-oxygen gas mixture flow into said blood oxygenator adjacent to said tubular array base terminus;

whereby a two-phase blood-oxygen-carbon dioxide gas mixture circulates inside said multiple oxygenator tubes, and a precisely temperature controlled heat transfer fluid circulates exteriorly to the oxygenator tubes inside the tube exchanger configuration.

2. An extra-corporeal blood oxygenator and blood temperature controller suitable for exchanging oxygen for carbon dioxide in patient circulating blood, wherein the improvement combination comprises:

a multiplicity of small diameter, oxygenator tubes, disposed in an equal length patterned parallel tubular array, said tubular array ranging from 4 to 24 inches long and said tubes ranging from one-sixteenth to five-sixteenths inches in a single tube diameter, said tubular array having a base terminus and a top terminus;

a base header plate securing said patterned array of oxygenator tubes at said array base terminus, providing a fluid impervious plate terminus for said array of tubes;

a top header plate securing said patterned array of oxygenator tubes at said array top terminus, providing a fluid impervious plate terminus for said array of tubes;

a tubular boundary case securing said base header plate, said top header plate and said multiple oxygenator tubes in an exchanger configuration;

a pair of heat transfer fluid conduits conductively secured to said boundary case adjacent to said base header plate, one said conduit draining said boundary case adjacent to said header plate, and the second said conduit extending inside and terminating inside said boundary case adjacent to said top header plate, draining said boundary case;

an inlet blood tubular manifold having a first blood manifold terminus coaxially secured to said boundary case adjacent to said base header plate, said first blood manifold terminus having an internal diameter at least equal to the internal diameter of said boundary case, said blood manifold having a base plate securing the second blood manifold terminus, providing a multiplicity of gas injection apertures normally disposed through said base plate;

an inlet oxygen gas manifold having a first gas manifold terminus concentrically secured to said blood manifold adjacent to said blood manifold base plate, said first gas manifold terminus having an internal diameter equal to the diameter of said base plate, a closure sealing the second gas manifold terminus opposite said blood manifold base plate;

at least one blood inlet conduit conductively secured to said blood manifold; and,

at least one oxygen gas inlet conduit conductively secured to said oxygen gas manifold;

whereby a two-phase blood-oxygen-carbon dioxide gas mixture circulates inside said multiple oxygenator tubes, and a precisely temperature controlled heat transfer fluid circulates exteriorly to the oxygenator tubes inside the tube exchanger configuration.

3. An extra-corporeal blood oxygenator and blood temperature controller suitable for exchanging oxygen for carbon dioxide in patient circulating blood, wherein the improvement combination comprises:

multiple, small diameter oxygenator tubes, having equal tubular lengths disposed in a patterned parallel array having a tubular array base terminus and a tubular array top terminus;

a base header plate securing said patterned array of oxygenator tubes at said array base terminus, providing a fluid impervious plate terminus for said array of tubes;

a top header plate securing said patterned array of oxygenator tubes at said array top terminus, providing a fluid impervious plate terminus for said array of tubes;

a tubular boundary case securing said base header plate, said top header plate and said multiple oxygenator tubes in an exchanger configuration;

at least one heat transfer fluid conduit conductively secured to said boundary case adjacent to said base header plate;

at least one heat transfer fluid conduit means conductively secured to said boundary case adjacent to said top header plate;

an inlet blood tubular manifold having a first blood manifold terminus coaxially secured to said boundary case adjacent to said base header plate, said first blood manifold terminus having an inside diameter at least equal to the external diameter of said boundary case, said blood manifold having a base plate securing the second blood manifold terminus, providing a locus of a multiplicity of gas injection apertures normally disposed through said base plate; and,

a blood diffusion tube secured concentrically to said first blood manifold terminus at a first tube terminus of said diffusion tube, said blood diffusion tube having a second tube terminus disposed a small spaced interval from said base plate, said first diffusion tube having an internal diameter at least equal to that of the base plate locus of said multiplicity of gas injection apertures, providing an annular blood inlet orifice;

whereby a two-phase blood-oxygen-gas mixture circulates inside the multiple oxygenator tubes and a precisely temperature controlled heat transfer fluid circulates exteriorly to the oxygenator tubes inside the tube exchanger configuration.