CA1145634A - Blood oxygenator with integral heat exchanger - Google Patents

Abstract

Abstract of the Disclosure A blood oxygenator includes a heat exchanger wherein heat transfer fluid flows through n tube which is ribbed along its length. The tube is positioned within a chamber connected in an extracorporeal blood circuit such that the blood is causes to flow over the exterior surface of the ribbed tube. In the preferred embodiment, the blood flows through a plurality of continuous, restricted area flow paths offering substantially uniform flow impedance to the blood, these restricted flow paths being provided by constructing the tube with an integral, substantially continuous, hollow, helical rib, and by forming the helically ribbed tube in a helical configuration mounted between an inner cylindrical column and an outer cylindrical ?hell such that the blood is caused to flow through the plural paths of restricted cross-sectional area provided by the helical flute. In one embodiment, the heat exchanger tube and blood chamber are formed as an independent unit adapted for use in the desired location of an extracorporeal blood circuit. In the other embodiments, the heat exchanger is formed integral with a blood oxygenator in which oxygen is absorbed into the blood and carbon dioxide is released therefrom. In the preferred embodiment, the heat exchanger also performs substantially all of the transfer of oxygen into the blood and the removal of carbon dioxide from the blood.

Description

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--CIPl 1 BLOOD OXYGENATOR ~ITH INTEGRAL

2 HEAT EXCHANGER
Abstract of the Disclosure A blood oxygenàtor includes a heat exchanger wherein heat transfer fluid flows through a tube which is ribbed along its 6 length. The tube is positioned within a chamber connectea in 7 an extracorporeal blood circuit such that the blood is caused 8 to flow over the exterior surface of the ribbed tube. In 9 the preferred embodiment, the blood flows through a plurali~y of continuous, restricted area ~low paths o fering substant~ally 11 uniform flow impedance to the blood, these restricted flow 12 paths being provided by constructing the tube with an integral~
13 substantially continuous, hollow, helical rib, and by forming 14 the helically ribbed tube in a helical configuration mounted between an inner cylindrical column and an outer cylindrical 16 shell such that the blood is caused to flow through the plural 17 paths of restricted cross-sectional area provided by the 18 helical flute. In one embodiment, the heat exchanger tube 19 and blood chamber are formed as an independent unit adapted for use in the desired location of an extracorporeal blood 21 circuit~ In the other embodiments, the heat exchanger is 22 formed integral with a blood oxygenator in which oxygen is 23 absorbed into the blood and carbon dioxide is released 2~ therefrom. In the p~eferred embodiment, the heat exchanger also perorms substantially all of the transfer of oxygen into 2~ the blood and the removal of carbon dioxide from the blood~

3 sackground of the Invention 3Extracorporeal circulation is and has been a routine 3 procedure in the operating room for several years. An important .~
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1 component in the ex-tracorporeaL blood circuit is a heat exchanger 2 used to lower the temperature of the blood prior to and during 3 a surgical procedure and subsequently rewarm the blood to normal

4 body temperature. The cooled blood induces a hypothermia which substantially reduces the oxygen consumption of the patient. The 6 published literature indicates that the oxygen demand of the 7 patient is decreased to about one-half at 30C, one-third at 8 25C and one-fifth at 20C. Light ~33 to 35C), moderate 9 (26 to 32C), and deep (20C and below) hypothermia are commonly used in clinical practice. Hyp~thermia is used to protect the 11 vital organs including the kidneys, heart, brain and liver during 12 o~erative procedures which require interrupting or decreasing 13 the perfusion.
14 A number of different structural configurations for heat exchangers have been used in the extracorporeal blood circuit 1 16 including hollow metal coils, cylinders and plates through which 17 a heat transfer fluid (typically water) is circulated. A survey 18 of a number of different t~pesof heat exchan~ers used in 19 extracorporeal circulation is included in the book entitled "Heart-~ung Bypass" by Picrr~ M. Gall~tti, M.D. et al, pages 21 165 to 170.
22 Notwithstanding the pLurality oE diEferent types of heat 23 exchanger conigurations which have been usecl in the past, there 2~ remains a need for a safe highly efficient heat exchanger desiyn which is simple to use and yet inexpensive enoug'n to be 26 manufactured as a disposable item. Thus, it is important that 27 there not be any leakage of the heat transfer fluid into the 28 blood. ~his fluid is typically circulating water flowing from 29 plumbing fixtures located in the operating room. Certain of the !
heat exchangers co~nonly used today for clinical bypass operations 31 have an upper pressure limit which is sometimes lower than the ;~ ~
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1 water pressures obtainable in -the hospital operating room. The 2 person who connects up the heat exc:hanger must therefore be 3 very careful to never apply the full force of the water pressure 4 through such a heat exchanger. Failing to take this precaution, ~ or an unexpec~ed increase in water pressure, could cause a 6 rupture within the heat exchanger resulting in contamination 7 of the blood flowing through the blood oxygenator.
8 Xt is also important that the heat exchanger have a high 9 performance factor in order to ~educe to a minimum the time required to lower the temperature to induce hypothermia and 11 subsequently raise the blood temperature to normal. Some 12 physiological degradation oE the blood occ~rs after a patient 13 is connected only a few hours to any of the bubble oxygenators 14 presently in use. Therefore, time saved in cooling and rewarming the blood is of direct benefit to the patient and 16 also giv~s the surgeon additional time to conduc-t the surgical 17 procedure if necessary.
18 Summary _f the Invention 19 The pre~ent invent;on relates to ~I hea-t exchanger for an extracorporeal blood circuit formecl by a mctal tube having 21 int~ralr hollow ribbin~ along its lcngth. l'his tube in turn 22 i5 formed in an over~ll helical configuration and mounted 23 between an inner cylindrical column extending within the 24 helically configured tube and an outer cylindrical shell.
Both the column and the shell are sized such that peripheral 26 portions of the ribbing are in contact with or are closely 27 proximate to the exterior wall of the column and the interior 28 wall of the cylindrical shell. ~he method employed for regulating 29 the temperature of blood using this type of heat exchange element involves flowing a heat transfer fluid through -the tube 31 and hollow rib and flowing the blood in a counterflow direction ~2 :

~1~5639 1 over -the exterior surEace of the ribbed tube. The co~bination 2 of the rib and the contactiny surfaces of the cylinder and 3 chamber confine the flow of blood substantially within pa-ths o~
4 restricted area and extended length provided by the ribbing.
~ The heat exchanger of the present invention enjoys several 6 significant advantages. Thus, its performance factor is very 7 high due to the long residence time of the blood, the high 8 conductivity o the heat exchange tube, the counterflow operation, 9 and high flow rate of the heat transfer fluid through the ribbed tube.
11 Heat exchangers cons-tructed in accordance with the present 12 invention have the reliability necessary for routine use in open 13 heart surgery and other procedures utilizing extracorporeal 14 circulation. The metal heat transfer fluid tube is an integral lS member which may be completely tested, both before and after 16 assembly into the blood chamber, for leaks under substantially 17 hi~hèr fluid pressures than are ever encountcred in an operating 18 room environment. The intcyral naturo o the h~at exchange 19 tube also pxovides an important advantage in that only the ends oE the ~ube pass through the wall o~ the blood carrying 21 chamber, thus minimizing the number of openinys in the chamber ¦ 22 which must be hermetically sealed. ~oreover, no connections 23 need to be made to the tube within the blood chamber since a 24 heat transfer fluid inlet and heat transfer fluid outlet are provided by the ends of the tube extending out from the chamber.
26 Any leak at the connection of the heat exchanger tube and the 27 fluid supply conduit will merely leak water or other heat 28 transfer fluid external of the blood chamber.
29 The ribbed heat exchanger tube may be mounted within a blood chamber separate from the blood oxygenator or may be 31 incorporated integral with the blood oxygenator, e.g., in the `' ~ 11~5~3~ ~

1 venous side within the blood-oxygen mixing chamber or in the 2 outlet side within the defoaminy chamber. In the embodiments 3 described below in which the heat exchanger is incorporated 4 within the mixing chamber of a bubble oxygenator the flow o ~ the blood and blood foam through the lengthy paths of restricted 6 ¦ cross-sectional area Gontributes to the blood-gas transfer 7 ¦ process, and, in one embodiment, this flow of blood and blood foam 8 ¦ effects substantially all of the blood-gas transfer process.
9 ¦ The heat exchangers of thi~ invention are sufficiently 10 ¦ economical in terms of material and manufacturing costs so 11 ¦ that it is disposed of a~ter use, thus avoiding the problems 12 ¦ and cost o sterilization in the hospital. In addition, the ~3 ¦ heat exchangers construc-ted in accordance with this invention 14 ¦ may be made biologically inactive and compatible with human 15 ¦ blood.
16 ¦ Brief Description of the Drawings 17 ¦ Figure 1 is a vertical clevational partial sectional view 18 ¦ of a blood oxygenator having an integral heat exchanger 19 constructed in accordance with the present invention;
Figure 2 is a partially sectional view taken along the 21 line 2-2 of Figure l;
22 Figure 3 is a vertical elevational partial sectional view 23 of another embodiment of a blood oxygenator having an integral 24 heat exchanger constructed in accordance with the present invention;
26 Figure 4 is a partially sectional view taken along the 27 line 4-4 of Figure 3;
28 Figure 5 is a v~rtical elevational partially sectional 29 view of a heat exchanger constructed in accordance with the present invention for use as a separate component in an 33l extracorporeal blood circuit;

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1 Figure 6 is a partially sect;onal view taken along the 2 line 6-6 of Figure 5;
3 Figure 7 is a perspective view o~ the port member providing 4 a fluid conduit, a ridged connector and rods for positioning the centrally located column shown in Figure 5;
6 Figure 8 is a vertical elevational partial sectional view 7 of another embodiment of a blood oxygenator having an integral 8 heat exchanger constructed in accordance with the present 9 invention;
Figure 9a is a par-tially sectional view taken along the 11 line 9-9 of Figure 8 showing the heat exchanger tube ends in 12 parallel alignment;
13 Figure 9b is a partially sectional view ta~en along the 14 line 9-9 of Figure 8 showing the heat exchanger tube ends in a non-parallel alignment;
16 ~igure 10 .is a vertical elevational sectional view along 17 the line 10-10 of ~'icJure 11 o the prcferred embodiment o~ a 18 blood oxyg~nator h~vlng an i.nternal. heat ~xchanger constructed 19 .in accordanc~ with thc prescnt invention;
Figure 11 is a front ~Levational view of -the preferred 21 embodiment o the prosent .inve~ntion;
22 FicJure 12 is a fraclmentary rear elevational view of the 23 defoamer section of the prcferred ~mbodiment of a blood 2~ oxycJenator having an integral heat exchanger constructed in accordance with the present invention;
26 Figure 13 is a hori~ontal partially sectional view taken 27 along line 13-13 o~ Figure 10;
28 Figure 14 is a bottom plan view taken along line 14-14 of 29 Figure 10, of the preferred embodiment of a blood oxygenator having an integral heat exchanger constructed in accordance ~1 with the present inven~ion, and ~5ti3~

1 Figure 15 i5 a vertical elevational partial sectional view 2 of the oxygenating cham~er of the preferred embodiment incorporati 3 a modified form of the heat transfer fluid tube.
4 Detailed Description of the Embodiment of Figures 1 and 2 ~ Referring to Figures 1 and 2, a blood oxygenator 10 is shown 6 incorporating a heat exchanger in accordance with this invention~
7 In this first embodiment as well as the other embodiments 8 described below and illustrated in Figures 3, 4, 8, 9a and 9b, ;
9 the blood oxygenator 10 is shown constructed in accordance with the invention disclosed and claimed in Canadian Patent ~o.
11 1,072,849 issued March 14, 1980 to Robert M. Curtis, entitled 12 BLOOD OXYGENATOR and assigned to Shiley Laboratories, Inc., the 13 assignee of the present invention. The bubble oxygenator chamber 1~ 11 is formed by a cylindrical shell 12 having its lower end closed off by a multi-port end cap 13. In the outer wall of 16 the end cap 13 are formed one or more blood inlet ports, one such 17 port 14 being connected to the extracorporeal blood circuit by 18 a flexible venous blood conduit lS. In the center of the cap 13 19 and extending through the wall thereof is an oxygen inlet port 20 including an outwardly extending ridged connector 21 for 21 attachment to a flexible oxygen line 22. ~he oxygen entering the 22 inlet port 20 is caused to form a plurality of oxygen bubbles 23 by means of a sparger 23. These bubbles flow through the venous 24 blood entering the annular trough 24 formed by the end cap 13 and the blood and oxygen mixture flow upwardly through a three-26 dimensional, open cellular mixing material 25 supported above 27 the sparger 23 within the chamber 11 by a pair of annular 28 retaining rings 26 and 27. The mixing material 25 is formed as 29 a cylinder so as to completely fill the cross-sectional space within the cylindrical shell 12 ~etween the annular retaining 3 rings 26 and 27.

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1 A column 30 is coaxially mounted within the upright 2 cylindrical shell 12 and supported by a horizontal rod 29 formed 3 as an integral cross brace of the annular retaining ring 27.
4 Both ends of the column 30 are hermetically sealed by caps 31.
The top of the chamber 11 is open. The arterializea blood 6 in the form of liquid blood and blood foam rises through this 7 opening and i5 contained in a channel 33 formed by a generally 8 half cylindrical shell 35 secured to a flat cover plate 36. As described in the Canadian Patent 1,072,849 of Robert M. Curtis, supra, the channel 33 leads to ~ defoamer chamb~r 37 wherein 11 the foam is collapsed and the arterialized whole blood collected 12 and returned to the extracorporeal blood circuits.
13 The heat exchanger comprises a pair of helically ribbed, 14 heat transfer fluid tubes 39 and 41. As shown, the hollow ribs 43 on these tubes have a triple helix configuration and provide 16 a continuous series of helical flutes 45 These helically 17 ribbed tubes 39 and 41 are advantageously constructed from a thin 18 wall tube of metal. Methods and apparatus for manufacturing such 19 helically ribbed tubes are described in U.S. Patent ~os. RE24,783 and 3,015,355.
21 An aluminum tube so formed and subsequently externally 22 coated with a thin coating of polyurethane provides a relatively 23 inexpensive, reliable and highly efficient heat exchange element.
24 The polyurethane film coating enables compatibility with human blood, this coating being advantageously applied electrolytically 26 as a powder and subsequently heated to provide a very 27 permanent coating over the exterior surface of the aluminum tube.
28 Stainless steel may also be used and has the advantage-of not 29 requiring any coating for blood compatibility but also has certain inherent disadvantages. Thus, this metal is a 31 substantially poor conductor of heat and is appreciably more 32 expensive than aluminum~ ¦

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1 ~s shown in Figures 1 and 2, the helicall~ ribbed tubes 39 2 and 41 are formed in a helical configuration and mounted between the cen-tral column 30 and the interior wall of the shell 12 such that peripheral portions o~ the ribs are closely proximate to and advantageously in con-tact with the exterior surface o 6 the column 30 and the interior wall 51 of the bubble oxygen 7 chamber 11. One end of each of the respective tubes 39 and 41 8 passes through hermetically sealed openings 53 and 55 formed in 9 the bottom of the chamber 11 and the opposite ends of the tubes i 10 extend through hermetically sea~ed openings 57 and 59 fo~med in ¦ 11 the cylindrical shell 35. Urethane glue provides an effective 12 sealant between the outer surface of the polyurethane coated 13 tube and the chamber 11 and shell 35 formed of polycarbonate 14 plastic.
1~ Shell 12 is advantageously extruded from polycarbonate 16 plastic and includes a longitudinal slit (not shown) such that 17 the shell may be opened up during manufacture to accept the 18 helically ribbed tubes 39 and ~ fter these tubes and the 19 inner column 30 are mounted in place, the slit edges of the shell are bonded togethcr by ethylene d~chloride.
21 Flex.iblQ conduits 61 and 63 are clamped to the upper ends 22 oE tubes 39 and 41 for suppl~ing ~ heat transEer fluid, typically 23 water under pressure, at the desired tempera~ure. The lower 2~ ends of the ribbed tubes 39 and ~1 are connected through 1exible conduits 65 and 67 to a drain. In this manner, the flow of heat 26 transEer fluid is opposite to that of the flow of the blood in 27 the oxy~enator chamber 11 to produce a counterflow-type heat 2 exchanger.
29 Since the embodiment of Figures 1 and 2 has many features 3 and advantages in common with the other embodiments described 3 below, such features and advantages are described in detail ~ ... 1 11~563~ ~

1 hereinafter. ~ primary di~tinguishin~ feature of -the embodiment 2 of F:igures 1 and 2 is the use of dual heat exchanger tubes 39 3 and 41. The heat transfer performance of a heat exchanger is 4 related to the flow rate of the heat transfer fluid. Although the single tube heat exchanger sho~m in the embodiments described he~einafter has been found to have a most satisfactory performance 7 in all operating room environments tested to date, the double 8 tube embodiment of Figures 1 and 2 would be particularly useful if 9 only very low flow rates oE heat transfer fluid were available during the extracorporeal procedure.
11 Detailed Description of the Embodiment of Figures 3 and 4 ' .
12 Another embodiment of a blooc oxygenator incorporating an 13 integral heat exchanger in accordance with this invention is 1~ sho~rn ln Figures 3 and 4. In this embodiment, the bubble oxyyenating chamber 70 is formed by a pair oE mating plastic 16 shells 71 and 73, each including a flat peri~heral flange 75 and 17 77 which may be joined together to form a complete cylindrical 18 sheJ.l 80. Shell halves 71 and 73 are advantag~ously formed by 19 vacuuln ~orminy or in~e~ction moldincJ polycarbonate plastic.
Cylinclrical ~h~ll 80 :includc ~n upp~r s.ide opening 81 and 2~ a lower s.idc-~ opening 83 each havin~ an inteyral outwardly 22 extending cylindrical boss 85 through which extcnd the respective 23 en~s o~ a si.ngle helically ribbed heat transfer fluid tube 87.
24 The inside wal]. oE these eY~tendi.ng cylindrical bosses 85 and the.
proximate exterior surface of the heat exchanger tube 87 are 26 bonded together to effect a hermetic seal. Ethylene dichloride 27 forms an excellent bond between shell halves formed of polycarbon t 28 plastic~
29 ~ particular advantage of the construction shown in Figures 3 and 4 is that the heating coil 87 may be easily assembled 31 within the chamber 70. When the ribbed tube 87 is formed into a ~ t;34 1 ¦ helical configuration, i-t has a tendency to open up, thereby 2 resulting in a certain amount of sliding frictional contact 3 with the inside walls of the chamber 70 and the exterior walls 4 of the column 90 when mounted in a unitary cylindrical shell such as shown in Figures 1 and 2 at 12. In the embodiment of 6 Figures 3 and 4, the interior column 90 is inserted within the 7 helically formed ribbed tube 87 and both members placed in the 8 shell half 73 such that the two ends of heat exchange tube 87 9 extend through the openings 81 and 83. The mating shell half 71 is placed over the heat excha~ger tube 87 and the mating 11 flanges 75 and 77 bonded together to provide a completely sealed 12 cylindrical shell unit 80. As in the previously described 13 embodiment, the peripheral portions of the ribs 91 of the tube 14 87 advantageously contact both the interior wall of chamber 70 and the exterior wall of the column 90.
16 A plastic rod 93 or other convenient means is affixed to .
17 the opposite portions of one or both of the shell halve~ 71 and 18 73 for supportîng the interior column 90 in a predetermined positi on 19 The mating shells 7l and 73 are necked in at their bottom and top to :Eorm respective openings 95 and 97 having cylindric~l 21 flanges 99 an~ 101. E`lange 101 snugl~ mates with the outside 22 diameter of a cylindrical member 103 on the bottom and a 23 cylindrical member lOS on th~ top respectively. As shown, a 24 small annular groove 107 may be formed in each of the flanges 99 and 101 to acc~mmodate an additional amount of bonding material 26 for providing a hermetic seal between the blood chamber 80 and 27 the cylinders 103 and 105.
28 Three dimensional, open cellular mixing material 109 is 29 supported within cylinder 103 by a pair of annular rings 111 and 113 attached to the inner wall of cylinder 103. This mixing 31 material comple.ely fills the cross-sectional interior of the 32 chamber 115 along the length of the mixing material.

~ 5~j34 ~., 1 An end cap 117 is secured to and closes off the bottom of 2 cylinder 103. ~his ca~ includes one or more blood inlet ports, 3 one such port 119 being connected to the extracorporeal blood 41 circuit by a flexible venous blood conduit 121. In the center 51 of the cap 117 and extending through the wall thereo~ is an 61 oxygen inlet port 123 attached to a flexible oxygen line 125.
71 The oxygen entering the inlet port 123 is caused to form a 81 plurality of oxygen bubbles by means of a sparger 127. These 9¦ bubbles flo~J through the venous blood entering the annular 10¦ trough 129 formed by khe end ca~ 117.
11 ¦ The upper cylinder 105 is secured within an opening 131 12 ¦ formed in a flat cover plate 133. The arterialized whole blood 13 ¦ rises through this opening and is contained in a channel formed 14 ¦ by the cylindrical shell 35 through which it is passed to a 15 ¦ defoamer chamber 37 as described in the Canadian Patent 1,072,849 o 16 ¦ Robert M. Curtis, supra.
17 ¦ Detailed Description of the Embodiment of Figures 5, 6 and 7 18 ¦ Although the invention has been described hereinabove as 19 ¦ integral with a blood oxygenator, the heat exchanger of this 20 ¦ invention may be incorporat~d in a separate unit to be used 21 ¦ elsewhe~e in extracorporeal blood circuits. Refexring now to 22 ¦ Figures 5, 6, and 7, the same type of helically ribbed heat 23 transfer fluid tube 135 is mounted in a spiral configuration 24 between an interior cylindrical column 137 and within a cylindrical chamber 139. Advantageously, peripheral portions 26 of the ribs are in contact with the exterior of the centrally 27 located column 137 and the interior wall of the chamber 139.
28 As described above with reference to the embodiment of Figures 29 1 and Z, the cylinder 145 is advantageously slit along its length for facilitating insertion of the heat transfer fluid 31 tube, after which the edges of the slit are bonded together.
32 Respective end caps 141 and 143 are secured at opposite .j ~S~4 -1 ends of the cylinder 145, each with a side opening having an 2 integral outwarclly extending cylindrical bosses 147 and 149 3 through which passes one end of the heat exchanger tube 135. A
4 suitable hermetic seal is formed between that portion of the S exterior wall 151 of the heat transfer fluid tube 135 and the 6 inside wall of bosses 147 and 149 to prevent any blood leakage.
7 Typically, a suitable adhesive such as urethane glue is used to 8 form a bond between the cylinder 145 and end caps 141 and 143 9 formed of polycarbonate plastic.
The end cap members 141 and`143 each have a central aperture 11 153 and 155 concentric with the spirally formed heat exchanger 12 tube 135. In each such aperture, there is mounted a port member 13 157 having a ridged connector portion 159 extending outwardly 14 from the heat exchanger, four support rods 161 extending inwardly into the heat exchanger, and a through conduit 163 1 16 through which blood passes into and out of the heat exchanger.
17 As shown in Figure 5, the four rods 1~1 make contact with the 1~ peripheral end surfacc 167 oE the centrally located column 137 19 to retain its ends equidistant Erom the end caps 1~1 and 143.
In use, flcxible water conduits 169 and 171 are attached 21 as shown to the extending ends 173 of the ribbed heat transfer 22 fluid tube 135,conduit 171 being connected to a suitable source ~3 of heat transfer fluid under pressure~ A counterflow of blood 2~ is introduced into the heat exchanger through a flexible conduit Z5 172 attached to the ridged connector 159. The cooled or heated 26 blood flows out of the heat exchanger through port member 157 27 into flexible conduit 174 attached to the ridged connector 159.
28 Detailed Description of the Embodiment of Figures 8, 9a and 9b _ . . . .
29 Another embodiment of a blood oxygenator incorporating an 30 ¦ integral heat exchanger in accordance with this invention is 31 ¦ shown in Figures 8, 9a and 9b. In this embodiment, the bubble 32 l ~ 5~ii3~1 ` `

1 ¦ oxygenator chamber 175 is formed by a cylindrical shell 177 21 having its lower end closed off by an end cap 179 having a side 31 opening 181 having an integrally attached, outwardly extending 41 cylindrical boss 183 formed in its ou-ter wall and a necked-in ~¦ portion 185 at its bottom including a cylindrical flange 187 61 surrounding a central aperture 189. This cylindrical flange of ql the end cap 179 is sized to mate with the external diameter of 81 ~ cylinder 191 and bonded thereto with a suitable material such 9¦ as ethylene dichloride. A three~-dimensional, open cellular lO ¦ mixing material 193 is supporte~ within cylinder 191 by 11¦ annular rings195 on its underside and 197 on its upper suriace~
1 12 ¦ As shown, material 193 completely fills the cross-sectional 1 13 ¦ interior oE the cylinder 191 along the length of the mixing 14 ¦ material.
15 ¦ The bottom of cylinder 191 is closed off by a multi-port 16 ¦ end cap 199. In the outer wall o the end cap 199 are ormed 17 ¦ one or more blood inlet E~orts, one such port 201 being connected 18 ¦ to the extracorporeal blood circuit by a flexible venous blood 19 conduit 202. In th~ c~nter of th~ cap 199 and extending through the wall thereoE is an oxygen inlet port 203. '~he oxygen 21 ~ntering the :inlet port 203 v:;a oxyg~n line 205 is caused to 22 o.rm a plurality of o~ycJen bubble~ by means of a sparger 207.
23 These bubbles 1OW through the venous blood entering the 2~ annular trough 209 formed by the end cap 199 and the blood and oxygen mi~ture flow upwardly through the three-dimensional, 26 open cellular mixing material 193 supported above the sparger 27 207 within the cylinder 191.
28 An upright column 211 is coaxially mounted within the 29 upright cylindrical shell 177 by a horizontal rod 213 supported in appropriate semicircular slots 215 formed in the top surface 3~ ¦ of the cylinder 191. Column 211 is advantageously formed by 32 ~

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a hollow cyclindrical member 217 whose ends are sealed by circular discs 219, one of which is shown at the lower end.
The top of the cylindrical shell 177 is closed by a similar end cap 180 having a side opening 182 having an integrally attached, outwardly extending cyclindircal boss 184 and a necked-in flanged portion of 186 surrounding a central aperture.
The inner wall of flange 186 engages the outer wall of a cylin-drical member 221 which in turn is attached to a flat cover plate 223. As in the previous embodiments of Figures 1, 2, 3, and 4, a generally half cylindrical shell 35 is secured to the top surface of the cover plate 223 for directing the liquid blood and blood foam into a defoamer chamber 37.
The helically ribbed heat transfer fluid tube 225 is formed into a helical configuration and mounted in the space between the central colum 211 and the inner wall of the cylin-drical chamber 177 such that peripheral portions of the ribs 227 of the tube 225 advantageously contact or are in very close proximity to the exterior wall of the column 211 and the interior wall of the chamber 177.
The configuration of Figure 8 is conveniently assembled by inserting the helically ribbed tube 225 along with the centrally located column 211 into the cylindrical shell 177. As described above with reference to the embodiments of Figures 1, 2, 5, 6, and 7, the shell 177 is advantageously slit along its length for facilitating insertion of the heat transfer fluid tube 225, after which the edges of the slit are bonded together.
As shown, the respective heat exchanger tube ends will then ex-tend above and below the shell 177. These ends are then inserted into the respective openings 181 and 182 formed in the upper and lower end caps 179 and 180.
A particular advantage of this construction is illustrated in Figures 9a and 9b. It has been found that after the helically

5~34 formed tube 225 is inserted in the chamber 177, the tube 225, even when manufactured in conformance with the particular set of specifications, does not always ultimately provide an identical helical configuration. In particular, as noted above, there is a tendency on the part of the spirally formed tube 225 to uncoil such that it may be difficult to orient the tube ends along the parallel axes as illustrated in Figure 9a. In the embodiment shown, the upper and lower end caps 179 and 180 may be oriented along non-parallel axes as shown in Figure 9b to accommodate whatever orientation the particular heat exchanger coil 225 assumes when inserted whithin the chamber 177.
Detailed Description of the Preferred Embodiment of a Pediatric Blood Oxygenator of Figures 10 Through 15 The preferred embodiment of a blood oxygenator incorporating an integral heat exchanger in accordance with this invention is shown in Figures 10 through 15. In the embodiment illustrated, a pediatric blood oxygenator comprises a bubble oxygenating chamber 240 formed by a pair of mating plastic shells, front shell 242 and rear shell 244, each including a flat peripheral 20 flange 246 and 248 which are joined together to form a complete cylindrical shell 250. Shell halves 242 and 244 are advanta-geously formed by vacuum forming polycarbonate plastic, and may be advantageously bonded together with ethylene dichloride.
Rear shell half 244 includes a blood outlet opening 252 hav.ing an integral rearwardly extending, tapered neck 254, which is generally elliptical in cross section. Front shell half 242 includes an upper side opening 256 and a lower side opening 258, each having an integral forwardly extending cylindrical boss 260 throu~h which extend the respective ends of a single helically ribbed heat transfer fluid tube 262.
The inside wall of these extending cylindrical bosses 260 and the proximate exterior surface of the heat exchanger X

~L11S~3'l 1 ~ tube 262 are bonded together to effect a hermetic seal.
2 ¦ ~s with the embod,ment illustrated in Figures 3 and 4, 3 ¦ the preferred embodiment is advantageously assembled by 4 ¦ inserting an extruded cylindrical interior column 264 within the 5 ¦ helically formed ribbed tube 262. Both ends of the column

6 ¦ 264 are hermetically sealed by end caps 265. The column

7 ¦ 264 and the tube 262 are placed in the front shell half 242

8 ¦ such that the two ends of the heat exchange-tube 262 extend

9 ¦ through the openings 256 and 258; The mating shell hal 244

10 ¦ is placed over the heat exchànge~r tube 262 and the mating flanges

11 ¦ 246 and 248 are bonded together to provide a completely sealed, .

12 ¦ cylindrical shell unit 250. The peripheral portion of the

13 ¦ ribs 266 of the tube 262 are closely proximate to and

14 ¦ advantayeously in contact with both the interior wall of the chamber 2~0 and the exterior wall of the column 264.
16 The mating shells 2~2 and 244 are necked in at the bottom 17 to form a passage 268 defin~d by a hollow cylindrical neck 270.
18 The neck 270 snugly mate~ with the exterior wall of a hollow~
19 injection~molded cylindrical membe~ 272. As shown, a small, annular ~roove 27~ may be ~ormed in the neck 270 to accommodate 21 additional bonding mater.ial to provide a hermetic seal between 22 the cylindrical shell unit 250 and the member 272.
23 The cylindrical member 272 includes one or more blood 2~ inlet ports 276, one such port 276 being connected to the extracorporeal blood circuit by a flexible venous blood 26 conduit (not shown).
27 An end cap 278 is secured to and closes of the bottom 28 of the cylindrical member 272. In the center of the cap 278 29 and extending from the bottom thereof is an oxygen inlet port 280 which is attached to a flexible oxygen line (not shown).
31 The oxygen entering the inlet port 280 is caused to form a ~ 5~ 3 ~ `

l plurality of oxygen bubbles by means of a sparger 282. These 2 bubbles flow through the venous blood en-tering the cylindrical 3 member 272. The sparger 282 fills the entire cross-section of 4 the cylindrical member 272, and rests on an annular support 283. The sparger 282 is sealed around its periphery to the 6 inner wall of the cylindrical member 272. Advantageously, the 7 sparger 282 will be selected to produce small sized oxygen 8 bubbles, e.g., of the order of .3 cm or smaller, for most 9 efficient oxygenation in this embodiment.
The venous blood and oxygen bubbles then rise into the 11 oxygenating chamber 240, where they contact the extericr of the 12 tuhe 262. The combination of the tube ribbing 266 and the 13 contacting surfaces of the cylinder 264 and the chamber 240 confin 3 l~ the flow of blood and oxygen bubbl~s substantially within paths o restricted area and extcnded length provided by the ribbing, thus 16 providing a tortuous path for the blood and axygen bubbles which 17 eff~ct a medically adequate transfcr of oxyg~n into the blood and 18 removal of carbon dioxide from th~ blood, without additional 19 mixing me~ns in the oxyg~nakor fluid path, ~ith~r upstxeam or downstream o the ribbed tubing.
21 The arterialized blood, in the form of blood and 22 blood fo~lmr then flows Ollt of thc oxygenating chamber through 23 the outlet opening 252 and the taperedr elliptical cross-section 2~ neck 254 into a defoamer chamber 284.
The neck 254 communicates with an opening 286 in a flat 26 vertical plate 288 forming a side ~ortion defoamer chamber top 27 cap 290, which may advantageously be formed by injection-molded 2 plastic polycarbonate. The opening 286 in turn communicates with 29 a fluid channel member 292r located within the top cap 290 I

1 ¦ which empcies.the arterialized blood into an annular defoamer 2 inlet chamber 294. ~ .
3 Sealingly fixed to the underside of the top cap 290 is an extruded hollow cylindrical cascade column 296 which runs through a central axial void 298 in a tubular defoamer 300. The 6 defoamer 300 is contained within a cylindrical injection-molded, 7 polycarbonate plastic defoamer shell 302 which is bonded 8 hermetically around its upper periphery to a downwardly extending 9 peripheral flange 304 depending from the top cap 290. The bottom of the defoamer shell 302 is sealed by a vacuum-formed, 11 polycarbonate plastic bottom cap` 306, which includes an inner 12 upwardly concave portion forming an annular seat 308 for a 13 defoamer lower support member 309. At the inner periphery of 14 the annular seat 308, the bottom cap extends still further upwardly to form a circular, centrally raised portion 310.
16 The support member 309 bends appropriately so as to contact the 17 inner surface of the raised portion 310, forming a circular 18 centrally.raised platform 311, the inner surface of which closes 19 the bottom portion of the axial void 298 and seals thè bottom of the cascade column 296.
21 The defoamer 300 shown is essentially as described in 22 the previously mentioned Canadian Patent 1,072,849. The defoamer 23 300 consists of an annular tube of reticulated porous sponge 24 materlal, such as polyurethane foam, and ls enclosed in a filter cloth 312 of nylon tricot or dacron mesh. The filter clot~ 312 26 is secured by nylon cable ties 314 to an annular upper flange 27 315 which extends upwardly from an annular defoamer upper 28 support member 316, which, in turn, is bonded to a downwardly 29 extending cylindrical boss 317 in the top cap 290; and a lower ~1 ~ c lindrical flange 318 extending downward ,~ -19-from the defoamer lower uppvrt member 309. soth -the ~loth 2 312 and the defoamer 300 are advan-tageously trea-ted with a 3 ¦ suitable antifoam compound.
4 ¦ The arterialized blood and blood foam flow from the inlet 1 5 ¦ chamber 294 int~ the annular axial void 298 through an annular ¦ 6 ¦ inlet 320. The majority of liquid blood entering the void 298 7 ¦ is guided by the column 296 to fill up the bottom of the void 298~ This liquid blood flows through the defoamer 300, as ¦ ~enerally shown by arrows 322. The blood and blood foam er.ter lO I at the upper end oE the defoamer 300 so that a substantial 11 ¦ portion of the interior wall surface of the defoamer 300 is . 12 contacted by the blood foam. As a result, a subs-tantial portion 13 of the defoamer 300 is used to separate the blood foam from the 1 14 entrapped gas such that the foam collapses and fluid blood flows 1 15 into an annular reservoir 32~ between the defoamer 300 and the 16 interior wall of the dcfoamer chamber 28~ and settles at the 17 bottom of the ch~mber 28~ and in the bottom cap 306. The 18 entrapped gclsr pr.im~r.ily c~xy~n ~nd CO2, which the defoamer 19 separatcs ou~ pass ~u~ o:E the ch~mber 284 ~hrough a vent 326 located in the upper end of the chamber at the juncture of the 21 top cap 290 and the cylindrical shell 302. ~s a result, only 22 whole liquid blood collccts i.n the reservoir 324, after having 23 been cleansed oE any particulate matter, such as blood 24 fragments and microemboli, by the filter cloth 312. The oxygenated, filtered whole blood then passes through one or 26 more outlet ports 328 located in the lower-most portion oE the 27 bottom cap 306 and is returned to the patient by a flexible 28 arterial conduit (not sho~n).
29 The defoamer chamber 284 advantageously includes externally applied indicia 330 of the volume oE blood contained therein.
311 The oxygena-tor may also include one or more externally threaded ~ ~5~3~

1 venous blood sampling ports 332 proximate the venous bloo~
2 inlet 276, and one or more arterial blood sampling ports 334 3 in the lower portion of the defoamer chamber 284~ One or more 4 priming ports 336 may also be provided in the top cap 290. Each of the ports 332, 334, and 336 is conveniently sealed by 6 screw caps 338.
7 Figure 15 shows a modification of the preferred embodLment 8 wherein the helically ribbed heat transfer fluid tube is .
9 replaced by a tube 340 having discrete spaced annular hollow ribs 342 formed in the wall of ~he tube along its length.
11 As with the heli.cally ribbed tube 262 shown in Figures 10 ,hrough 12 14, the peripheral portions of the annular ribs 342 are closely 13 proximate to and advantageously in contact with both the interior l* wall of the chamber 240 and the exterior wall of the column 264. These discrete spaced annular ribs provide a plurality 16 of discontinuous flute passages around the tube whichr when their 17 individual lengths are added, total a distance considerably 18 longer than the length of the ~luid conduit. The combination 19 of the ribs 342 and the contacting surfaces o the column 264 and the chamber 240 confine the flow of blood and oxygen bubbles 21 substanti~lly wit:hin extended length, restricted area paths and 22 prov.ide a thorough mixi.ng o the blood and o~ygen bubb~esl therebs 23 cffecting a medically adequato transfer of oxygen into the blood 2~ and CO2 from the blood w:ithout addi-tional mixing means. Except for the configuration of the ribbing on the tuber the embodiment 26 illustrated in Fiyure 15 is in all other respects iden-tical to 27 that illustrated in Figures 10 through 14.
28 The helically-ribbed heat transfer fluid tube 262t shown 29 in Figures 10 through 14 r is advantageously formed of a continuou length of aluminum tubing with the exterior coated with a 33l polyurethane coat.ng, as discussed above or, alternativelyr the I( ~ ~s~3~a ..

1 the exterior surfaces are electrolytically oxidized, or anodizedr 2 to form a "hard anodized" coating, as disclosed and claimed in 3 applicant's copending Canadian application Serial No. 317,615, 4 filed December 8, 1978.
~ The annular-ribbed heat transfer fluid tube 340, shown in 6 Figure 15 r may likewise be formed of anodized or polyurethane 7 coated aluminum. Alternativelyr it may be formed of brass or 8 bronze tubing having a blood compatible coating.
9 The preferrèd embodiment of~ Figures 10 through lS is suited for use in both adult and pediatric applications. It is 11 advantageous to construct the oxygenating chamber with as small 12 a volume as possible, consistent with the requirements for heat 13 and gas transfer so as to minimize the amount of blood contained 14 in the oxygenating chamber during use.
~y way of specific example, a pediatric oxygenator with an 16 integral heat exchanger constructed in accordance with the 17 preferred embodiment comprises an oxygenating chamber 240 ha~ing 18 an inside diameter of approximately two inches, and contains a 19 central cylindrical column 264 having an outside diameter of approximately one inch. The heat exchanger tube 262 is formed 21 of h~lf-inch outside diameter aluminum tubing, which, when 22 twisted to form the helical ribbing, has an outside diameter of 23 .490 inches from ridge to ridge of the ribs and .340 inches from 24 groove to groove between the ribs. The wall thickness of the tube 262 is approximately .014 inches. The tubing is anodized, 26 as hereinabove described, and the anodized coating adds 27 approximately .001 inches to the wall thic~ness and approximately 28 .002 inches to the respective outside diameter measurements.
29 When completely assembled, and incorporating the heat exchanger tube 262 and the central column 264, the oxygenating chamber has 332 a capacity of approximately 100 milliliters. The adult sized , -22-~ 1145ti3 ~

¦ unit is larger in scale with a capacity of approximatèly 450 2 I milliliters.
3 ¦ In constructing the oxygenating chamber, it is necessary to ~¦ coil the tube 262 tightly so as to have the peripheral portions 51 of the ribbing come into contact with, or at least be closely 6 ¦ proximate to, the exterior surface of the central column 264.
7 ¦ The hollow ribbing on the tube enables the tube to be so coiled 8 ¦ without kinking. Any kinking would be quite deleterious since it 9 ¦ would result in obstructed fluid flow and also a weakened wall 10 ¦ structure, which would make the tube prone to leaks. This ll ¦ ability to be tightly coiled displayed bY the ribbed tubing 12 ¦ makes possible an oxygenating chamber having the relatively small 13 ¦ capacity of lO0 milliliters, and such a capacity has been found l~ ¦ to be particularly advantageous in pediatric applications.

15 ¦ Tes-ts conducted on both adult and pediatric units constructed

16 ¦ in accordance with this embodiment show a medically adequate

17 ¦ transfer of oxygen into ~he blood and removal of carbon dioxide

18 ¦ thereErom. In general, tests conducted on identical units with

19 and without the~ mixing material of the prior e~bodiments show that to achicve a given lcvel of oxygenation compared to these previous i 2~ described embodiments, a higher level of ox~gen flow rate is 22 required Eor a ~iven blood fLow rate. Ln addition these tests 23 ~how that the level of ox~genation increases with an inc~ease of the blood flow rate, e.g., at a blood flow oE 6 liters per minute , the-oxygen gas content of the arterialized blood output 26 from the embodiment oE Figures 10-14 with a l:l o~ygen to blood 27 ratio closely approaches the oxygen gas content achieved with the 28 prior embodiments, whereas at a blood flow rate of 2 liters per 29 minute, a ratio of greater than 1:1 is required to achieve oxygen gas content levels which are comparable to those achieved with 32 l ~ -23-lll5~i3/~ ~

1 the prior embodiments of Fic3~lres 1, 2, 3, 4, 8 and 9.
2 sy way of specific ~Y.ample, th2 gas transfer da-ta obtained 3 duriny a specific tes-t are listed in Table 1. This test was 4 conducted November 1, 1977, on a female Suffolk lamb weighing ~ 26 kg which underwen-t a six-hour, partial veno-arterial 6 cardiopulmonary bypass using the oxygenator o~ the preferred 7 embodiment. The data indicate efficient oxygenation with ~2 8 removal in an oxygenator having an integral heat exchanger 9 constructed in accordance with the present invention, and lacking any additional mixing structure in the oxygenating 11 chamber. ~he oxygenator used in these tests used a heat exchanger anodized aluminum as previously described.

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A number of factors contribute to the excellent heat trans-fer efficiency of the present invention and ir.clude the following:
1. ihe combination of the flutes of the heat transfer fluid tube and proximate inner and outer surface walls of the blood chamber provides a plurality of continuous, restricted area flow-paths offering substantially uniform flow impedance to the blood and blood foam. As a result, the blood and blood foam have a long residence time in the heat exchanger. Mbreover, this structure avoids areas of stagnation which otherwise hinder heat transfer from the blood and are also undesirable from a physiological standpoint. In the tests conducted to date on the embodiments of Figures 3, 4, 8, 9, and 10 through 14, the blood and blood foam was observed to be in constant circulation through these restricted flow paths and having extensive contact with and long residence time with the heat exchanger tube. Only minimal areas of stagnation were evident.
2. The extensive hollow ribs of the heat transfer fluid tube provide a substantial surface area for transferring heat from the heat transfer fluid to the blood and blood foam. The tubes used in the above-described embodiments typically have an external surface area of the order of 200 to 300 square inches.
The surface area of the tubes ued in the pediatric units is on the order of 100 square inches.
3. Although the direction of fluid flow through the heat exchanger tube may be in either direction, the heat transfer performance is optimized by operating as a counterflow exchanger, i.e., in the manner described above wherein the blood and heat transfer fluid flow in generally opposite directions.
4. The wall thickness of the ribbed tube may be relatively thin, e.g., .014 to .016 inch, so as to further improve its heat transfer properties. As disclosed and claimed in the copending application Serial No. 317,615, supra, very high thermal ccnductivity is achieved using an anodized aluminum tube. The 3'~

polyurethane coated aluminum tubes described herein also have a high thermal conductivity, notwithstanding that the polyurethane coating reduces the overall thermal conductivity of the aluminum tube by some 15 percent.
5. The ribbed heat exchanger tube has a sufficiently large average internal diameter, e.g., approximately 0.5 inch, for providing a high rate of flow of the heat transfer fluid, e.g., 21 liters/minute of water. The average inside diameter of the tubes used in pediatric units is approximately 0.34 inch and accommodates a proportionately lower flow rate.
Although the integral heat exchanger embodiments described above have incorporated the heat exchanger within the oxygenation chamber, it will be apparent to those knowledgeable in the art that the significant features of the heat exchanger tube which contribute to its high heat transfer efficiency will be beneficial in other locations within the blood oxygenator.
Thus, by way of specific example, the ribbed heat transfer fluid tube may be located within the defoamer column such that the blood flowing within or through the defoamer member is caused to circulate through the flutes of the heat exchanger tube.
The integral nature of the heat exchanger tube also pro-vides an important advantage in providing an effective seal for preventing any possible contamination of the blood by the heat transfer fluid. Thus, in the present invention, the heat exchanger tube is advantageously constructed as a continuous member with no connections being made to the tube within the blood chamber. Any leak at the connection of the heat exchanger tube and the flexible water or other heat transfer fluid conduit 11451j39L

I ~ill merely leak water or other fluid external of the blood chamber.
In addition, the thickness of the heat exchanger tube, 4 af.ter being formed into a ribbed configuration, is ample to ~ handle fluid pressures considerably higher than those encountered 6 in clinical practice. This is important since typically the 7 heat exchanger tube is connected directly to a water faucet in 8 the operating room which, turned full on, may deliver water at a 9 pressure as high as 60 psi. Inadvertent closing of the drain discharge can then build up pressure within the heat exchanger 11 to 60 psi. Such high pressures can rupture certain prior art 12 heat exchanger configurations concurrently in extensive use in 13 extracorporeal blood circuits. In contrast, in the present 14 invention, the ribbed tubes have been tested at substantially high pressures, i.e., 120 psi without any indication of structural 16 damage or rupture.
17 In add.iti.on to its excellcnt heat transEer characteristics, ~ 18 the present .invent.ion is efficiently and economically manufactured .
I 19 Thus, the ribbed tube is an integral unit which may be completely tested for leaks before and/or after assembly into the blood 21 carrying chamber. ~lso, .it has been found that pin hole or 22 other small leaks in the aluminum heat exchanger tube are sealed 2 by the polyurethane coating. Advantageously, the coa~iny covers 24 the entire tube includiny those portions extending through the 26 sealed openings of the blood chamber so as to provide this 2 additional protection against leakage.

L~/HJK:Pb32 -28-

Claims (24)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for regulating the temperature of venous blood in an extracorporeal blood circuit and simultaneously oxygenating said venous blood comprising the steps of:
introducing said venous blood and oxygen bubbles into a chamber;
oxygenating said venous blood by flowing the blood and said oxygen bubbles over the exterior surface of a conduit in said chamber, said conduit having an integral hollow rib means along its length providing a flute passage means whose total length is considerably longer than the length of said conduit; and regulating the temperature of said blood by flowing heat transfer fluid of a predetermined temperature through the interior of said conduit and hollow rib means during said oxygenating step.

2. A method for regulating the temperature of venous blood in an extracorporeal circuit and simultaneously oxygena-ting said venous blood comprising the steps of:
introducing said venous blood and oxygen bubbles into a chamber;
oxygenating said venous blood by flowing the blood and said oxygen bubbles through paths of restricted area and extended length provided by a flute means formed by an integral hollow rib means along the length of a tube in said chamber; and regulating the temperature of said blood by flowing heat transfer fluid of predetermined temperature through the interior of said tube and said hollow rib means during said oxygenating step.

3. A method for regulating the temperature of venous blood in an extracorporeal blood circuit and simultaneously oxygenating said venous blood comprising the steps of:
oxygenating said blood by flowing the blood and oxygen bubbles through a plurality of paths of restricted area and extended length provided by a flute means formed by (i) an integral, hollow rib along the length of a tube and (ii) a wall of a chamber connected in said extracorporeal blood circuit which is in contact with or located proximate to peripheral portions of said rib, and simultaneously regulating the temperature of said blood by flowing heat transfer fluid of predetermined temperature through the interior of said tube and hollow rib during said oxygenating step.

4. A blood oxygenator having an integral heat exchanger for regulating the temperature of the blood flowing in an extracorporeal blood circuit comprising:
an oxygenating chamber;
first means for introducing blood and bubbles of oxy-gen into said oxygenating chamber for forming blood foam within said chamber, and second means for both (a) oxygenating the blood flowing in said blood circuit by transferring oxygen into the blood and removing carbon dioxide from the blood and (b) simultaneously regulating the temperature of said blood, said second means comprising a heat transfer fluid conduit including heat exchange fluid inlet and outlet means and having rib means along its length, said rib means being located in contact with or closely proximate to the inner wall of said oxygenating chamber so that substantially all of said blood and blood foam produced by said first means flows in contact with external surfaces of said heat transfer fluid conduit through a plurality of restricted area, extended length flow paths around the exterior of the heat transfer fluid conduit provided by said rib means in combination with said inner wall prior to any substantial defoaming of the blood foam and with minimal areas of stagnation for said blood and blood foam with a resulting relatively long residence time of the blood and blood foam in contact with said heat transfer fluid conduit.

5. The blood oxygenator having an integral heat exchange of claim 4, wherein said rib means provide a flute passage means whose total length is considerably longer than the length of said conduit.

6. The blood oxygenator having an integral heat exchanger of claim 5 wherein said continuous helical flute passage is considerably longer than the length of said fluid conduit.

7. The blood oxygenator having an integral heat exchanger of claim 4 wherein said rib means is a plurality of discrete hollow annular ribs disposed along the length of said heat transfer fluid conduit.

8. The blood oxygenator having an integral heat exchanger of claim 7 wherein said annular ribs provide a plurality of annular flute passages around the tube which total a distance considerably longer than the length of the fluid conduit.

9. The blood oxygenator having an integral heat exchanger of claim 4, wherein said second means effects substantially all of the transfer of oxygen into the blood and the removal of carbon dioxide from the blood while said blood and blood foam are in contact with second means.

10. The blood oxygenator having an integral heat exchanger of claim 9 wherein said chamber has first and second sealed openings through which extend the opposite ends of said heat transfer fluid conduit whereby connections to said heat exchange fluid inlet and outlet means are made outside said chamber.

11. The blood oxygenator having an integral heat exchanger of claim 9 wherein the flow of heat transfer fluid through said heat transfer fluid conduit is substantially opposite the direction of the flow of said blood to provide a counterflow operation.

12. The blood oxygenator having an integral heat exchanger of claim 9 wherein said heat transfer fluid conduit has three substantially equally spaced, substantially continuous hollow helical ribs along its length in a triple helix configuration providing plural of said continuous helical flute passages considerably longer than the length of said fluid conduit.

13. The blood oxygenator having an integral heat exchanger of claim 9 wherein said heat transfer fluid conduit is a continuous length of metal tubing having said rib means formed integrally therein.

14. The blood oxygenator having an integral heat exchanger of claim 9 wherein said heat transfer fluid conduit has an overall helical configuration.

15. The blood oxygenator having an integral heat exchanger of claim 14 wherein a centrally located cylindrical column is located within said chamber and said helically configured heat transfer fluid conduit is located between said column and the interior wall of said chamber so that said exterior wall of said column is located in contact with or closely proximate to peripheral portions of said rib means.

16. The blood oxygenator having an integral heat exchanger of claim 9 wherein said chamber comprises two halves mated along a seam, said halves being located over and surrounding said heat transfer fluid conduit and bonded together to form a hermetic seal along said seam.

17. The blood oxygenator having an integral heat exchanger of claim 12 wherein one of said chamber halves includes first and second openings through which extend the opposite ends of said heat transfer fluid conduit.

18. A blood oxygenator having an integral heat exchanger comprising:
an oxygenating chamber;
first means for introducing venous blood and bubbles of oxygen into said oxygenator chamber for forming blood foam; and second means for (a) oxygenating said venous blood by transferring oxygen into the venous blood and removing carbon dioxide from the venous blood and (b) simultaneously regulating the temperature of said venous blood, said second means comprising:
a heat transfer tube including heat exchange fluid inlet and outlet means and having integral rib means along its length for providing a flute passage means whose total length is considerably longer than the length of said tube, said tube having an overall helical configuration with peripheral portions of said rib means in contact with or closely proximate to a wall of said oxygenating chamber so that substantially all of said venous blood and blood foam flows in contact with external surfaces of said heat transfer tube through a plurality of flow paths of restricted area and extended length around the exterior of said tube prior to any substantial defoaming of the blood foam, said flow paths being with minimal areas of stagnation for said venous blood and blood foam and formed by said flute passage in combination with a wall of said oxygenating chamber for achieving long residence time of the blood and blood foam in contact with said heat transfer tube.

19. The blood oxygenator having an integral heat exchanger of claim 18, wherein said rib means is a plurality of discrete hollow annular ribs disposed along the length of said heat transfer fluid conduit.

20. The blood oxygenator having an integral heat exchanger of claim 18 wherein said second means effects substantially all of the transfer of oxygen into the blood and the removal of carbon dioxide from the blood while said blood and blood foam are in contact with said second means.

21. The blood oxygenator of claim 20 wherein a centrally located column is located in a chamber of said oxygenator and said heat transfer tube is formed in a helical confi-guration located in the space between the exterior wall of said column and the interior wall of said chamber so that peripheral portions of said rib means are in contact with or closely proximate to the exterior wall of said column and the interior wall of said chamber.

22. The oxygenator of claim 20 wherein said oxygenating chamber comprises two halves mated along a seam, one of said halves having first and second sealed openings through which extend the opposite ends of said heat transfer fluid conduit.

23. A blood oxygenator having an integral heat exchanger for regulating the temperature of the blood flowing in an extracorporeal blood circuit comprising:
an oxygenating chamber;
first means for introducing blood and bubbles of oxy-gen into said oxygenating chamber; and second means for both (a) effecting substantially all of the transfer of oxygen into the blood and the removal of carbon dioxide from the blood and (b) simultaneously regul-ating the temperature of said blood, said second means comprising:
a heat transfer fluid conduit including heat exchange fluid inlet and outlet means and having a substantially continuous hollow helical rib along its length providing a continuous helical flute passage considerably longer than the length of said flute conduit, said helical rib being located in contact with or closely proximate to wall means of said blood oxygenator so that substantially all of said blood and blood foam produced by said first means flows in contact with external surfaces of said heat transfer fluid conduit through a plurality of restricted area, extended length flow paths around the exterior of the heat transfer fluid conduit provided by said helical flute passage in combination with said wall means prior to any substantial defoaming of the blood foam with a resulting relatively long residence time of the blood and blood foam in contact with said heat transfer fluid conduit.

24. A blood oxygenator having an integral heat exchanger for regulating the temperature of the blood flowing in an extracorporeal blood circuit comprising:
an oxygenating chamber;
first means for introducing blood and bubbles of oxygen into said oxygenating chamber;
second means for both (a) effecting substantially all of the transfer of oxygen into the blood and the removal of carbon dioxide from the blood and (b) simultaneously regulating the temperature of said blood, said second means comprising:
heat transfer means having a plurality of annular ribs along its length providing a blood flow passage considerably longer than the length of said heat transfer means, said ribs being located in contact with or closely proximate to wall means of said blood oxygenator so that substantially all of said blood and blood foam produced by said first means flows in contact with external surfaces of said heat transfer means through a plurality of restricted area, extended length flow paths around the exterior of the heat transfer means provided by said blood flow passage in combination with said wall means prior to any substantial defoaming of the blood foam with a resulting relatively long residence time of the blood and blood foam in contact with said heat transfer means; and third means coupled to said heat transfer means for supplying or removing heat energy from said heat transfer means.