CA1134233A - Blood oxygenator with integral heat exchanger - Google Patents

Abstract

BLOOD OXYGENATOR WITH INTEGRAL HEAT EXCHANGER
Abstract of the Disclosure A blood oxygenator includes a heat exchanger wherein heat transfer fluid flows through an aluminum tube having an integral, substantially continuous hollow helical rib along its length providing a substantially continuous helical flute. The tube is positioned within a chamber connected in an extracorporeal blood circuit such that the blood is caused to flow over the anodized exterior surface of the helically 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 forming the helically ribbed tube in a helical configuration mounted between an inner cylindrical column and an outer cylindrical shell 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.

Description

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26 Background of the invention ~
27l Extracorporeal circulation is and has been a routine 281 procedure in the operating room for se~eral years.: An important 291 co~ponent in the extracorporeal blood circuit i5 a heat exchanger ~ol ,. *
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~3~ 33 1 used to lower the temperature of the blood prior to and during 2 a surgical procedure and subsequently re~7arm the blood to normal

3 body temperature. The cooled blood induces a hypothermia which

4 substantially reduces the oxygen consumption of the patient. The published literature indicates that the oxygen demand of the 6 patient is decreased to about one-half at 30C, one-third at 7 ¦ 25C and one-fifth at 20~C. Light (33 to 35C), moderate 8 ¦ (26 to 32C), and deep (20C and below) hypothermia are commonl~
9 ¦ used in clinical practice. Hypothermia is used to protect the vital organs including the kidneys, heart, brain and liver during 11 operative procedures which require interrupting or decreasing 12 the perfusion.
13 A number of different structural configurations for heat 14 exchangers have been used in the extracorporeal blood circuit including hollow metal coils, cylinders and plates through which 16 a heat transfer fluid (typically water) is circulated~ A survey 17 of a number of different type of heat exchangers used in 18 extracorporeal circulation is included in the book entitled 19 "Heart-Lung Bypass" by Pierre M. Galletti, M.D. et alj pages 2P 165 to 170.
21 Notwithstanding the plurality of different t~pes of heat 22 exchanger configurations which have been used in the past, there 23 remains a need for a safe highly efficient heat exchanger deslgn 2~ which is simple to use and yet inexpensive enough to be 25 ¦ manufactured as a disposable item. Thus, it is important that 26 ¦ there not be any leaXage of the heat transfer fluid into the 27 ¦ blood. This fluid is typically circulating water flowing from 28 plumbing fixtures located in the operating room. Certain of the 29 ¦ heat exchangers commonly used today for clinical bypass operations 33 ~ have an uppe pressure limit which is sometimes lower than the ~ . ,. : ., . :. .

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~ 233 1 wa-ter pressures obtainable in the hospital operating room. The 2 person who connects up the heat exch~nger 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, S or an unexpected 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 It is also ir.lportant that the heat exchanger have a high 9 performance factor in order to reduce to a minimum the time 10 required to lo~er the temperature'to induce hypothermia and 11 subsequently raise the blood temperature to normal. Some 12 physiological degradation of the blood occurs after a patient 13 is connected only a few hours to any of the bubble oxygenators 1~ presently in use. Therefore, time saved in cooling and 1~ rewarming the blood is of direct benefit to the patient and 16 also gives the surgeon additional time to conduct the sùrgical 17 procedure if necessary. Heretofore/ stainless steel tu~ing has 18 often been used in blood environments as a heat exchange element 19 b~cause it is biologically compatible with human blood.~ However, 20 heat exchangers made with stainless steel tubing are very 21 expensive and are not economically suitea for a throw away 22 disposable unit.
23 Summary of the Invention 2~ The present invention relates to a heat exchanger for an 25 extracorporeal blood circuit formed by an aluminum tube having 26 one or more integral hollow ribs along its length and having 27 substantially its entire exterior surface electrolytically 28 oxidized to form a hard anodized coating. ~his tube in turn is 29 formed in an overall helical configuration and mounted between 30 an inner cylindrical column extending within the helically 3~

~ ~34z3.~ l 1 configured tube and an outer cylindrical shell. Both the col~n 2 and the shell are sized such that peripheral portions of the rib are in contact with or are closely proximate to the exterior wall of the column and the interior wall of the cylindrical shell.
S The method employed for regulating the temperature of blood using 6 this type of heat exchange element involves flowing a heat transfer 7 fluid through the tube and hollow rib and flowing the blood in a 8 counterflow direction over the exterior surface of the g ribbed tube. The combination of $he rib and the contacting surfaces of the cylinder and chamber confine the flow of blood 11 `substantially within paths of restricted area and extended length 12 provided by the hollow ribbing.
13 The heat exchanger of the present invention enjoys several 1~ significant advantages. Thus, its performance factor is very 15 high due to the long residence time of the blood, the high 16 conductivity of the heat exchange tube, the direct contact o the 17 blood wit`h the hard anodized surface, the counter10w operation, 18 and high flow rate of the heat transfer ~luid through the ribbed 1~ tube.
Heat exchangers constructed in àccordance ~ith the present 21 invention have the reliability necessary for routine use in open 22 heart surgery and other procedures utilizing extracorporeal 23 circulation. The anodized metal heat transfer fluid tube is an 24 integral member which may be completely tested, both before and aft 3 25 assembly into the blood chamber, for leaks under substantially 26 higher fluid pressures than arè ever encountered in an operating 27 room environment. The integral nature oE the heat exchange 28 tube also provides an important advantage in that only the 29 ends of the tube pass through the wall of the blood carrying 31 chamber, thus minimizing the number of openin~s in the chamber . .
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3~33 1 which rnus-t be hermetically sealed, Moreover, no connections ~ need to be made to the tube within the blood chamber since a 3 heat transfer fluid inlet and heat transfer fluid outlet are provided by the ends of the tube ex-tending out from the chamber.
~ Any leak at the connection of the heat exchanger tube and the 6 fluid supply conduit will merely leak water or other heat 7 transfer fluid external of the blood chamber.
8 The hollow ribbed heat exchanger tube may be mounted within 9 a blood chamber separate from the~blood oxygenator or may be 1~ incorporated integxal with the blood oxygenator, e.g., in the 11 venous side within the blood-oxygen mixing chamber or in the 12 outlet side within the defoaming chamber. In the embodiments 13 described below in which the heat exchanger is incorporated 14 within the mixing chamber of a bubble oxygenator the flow o~
15 the blood and blood foam through the lengthy paths of restricted 16 cross-sectional area contributes to the blood-gas -transfer 17 pxocess.
18 The heat exchangers of this invention are sufficiently 19 economical in terms of material and manufacturing costs so 20 that it is disposed of after use, thus avoiding the problems 21 and cost of sterilization in the hospital. Xn additionr the 22 heat exchangers constructed in accordance with this invention 23 may be made biologically inactive and compatlble with human `
2~ blood. A significant advantage o~ this invention is that the 25 anodized exterior surface of the metal heat exchanger is 26 compatible with human blood. Thus, no other coating such as a 2~ plastic coating is required over this andized tube so that the 28 blood may flow directly in contact with this surface and achieve 29 a very high perEormance factor.
~0 Brief Description of the Drawings 31 Figure 1 is a vertical elevational partial sectional vie~

32 of a blood oxygenator having an integral heat exchanger .: ~ ,.

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1 constructed in accordance with the present invention;
2 Fi~ure 2 is a partially sectional view taken along the 3 line 2-2 of Figure l;
4 Figure 3 is a vertical elevational partial sectional view

5 of another embodiment of a blood oxygenator having an integral ~ heat exchanger constructed in accordance with the present 7 invention;
8 Figure 4 is a partially sectional view taken along the 9 line 4-4 of Figure 3;
Figure 5 is a vertical elevational partially sectional 11 ¦view of a heat exchanger constructed in accordance with the 12 ¦present invention for use as a separate component in an 13 ¦extracorporeal blood circuit;
14 ¦ Figure 6 is a partially sectional view taken along the 15 ¦line 6-6 of Figure 5;
16 ~ Figure 7 is a perspective view of the port member providing 17 ¦a fluid conduit, a ridged connector and rods for positioning the 18 ¦centrally located column shown in Figure 5;
19 ¦ Figure 8 is a vertical elevational partial sectional view 20 of another embodiment of a blood ox~genator having an integral 21 heat exchanger constructed in accordance with the present 22 invention;
23 Figure 9a is a partially sectional view taken along the 2~ line 9-9 of Figure 8 showing the heat exchanger tube ends in 25 parallel alignment;
26 Figure 9b is a partially sectional view taken along the 27 line 9-9 of Figure 8 showing the heat exchanger tube ends in 28 a non-parallel alignment;
29 Figure 10 is a vertical elevational sectional vlew of the 33o preferred embodiment of a blood oxygenator having an integral hea' 32 :
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1 exchanger constructed in accordance with ~he present in~ention;
2 Figure 11 is a front ele~ational view of the preferred 3 embodiment of a blood oxygenator having an integral heat exchanger constructed in accordance with the presen~ invention;
~ Figure 12 is a rear elevational view of the preferred

6 embodiment of a blood oxygenator having an integral heat exchanger

7 constructed in accordance with the present invention;

8 Figure 13 is a top plan view taken along line 13-13 of Fig~

9 10; and Figure 14 is a bottom plan view taken along line 14-14 o~
11 Fig. 10.
12 Detailed Description of the Embodiment of Figures 1 and 2 13 Referring to Figures 1 and 2, a blood oxygenator 10 is shown 14 incorporating a heat exchanger in accordance with this invention~
15 In this first embodiment as well as the other embodiments 16 described below and illustrated in Figures 3, 4, and 8 through 14 17 the blood oxygenator 10 is shown constructed in accordance with 18 the invention disclosed and claimed in Canadian Pàtent ,072,849 issued March 14th, 1980 to Robert M. Curtis, entitled BLOOD OXYGENATOR and assigned to Shiley Laboratories, Inc.~ the 21 assignee of the present invention. The bubble oxygenator chamber 22 11 is formed by a cylindrlcal shell 12 having its lower end closed off by a multi-port end cap 13. In the ou~er wall of 2_ the end cap 13 are formed one or more blood inlet ports, one such port 14 being connected to the extracorporeal blood circuit by 26 a flexible venous blood condult 15. In the center of the cap 13 28 and extending through the wall thereof is an oxygen inlet port 20 including an outwardly extending ridged connector 21 for 29 attachment to a flexible oxygen line 22. The oxygen entering the 3 inlet port 20 is caused to form a plurality of oxygen bubbles ~4r 3l I - ?-` ~3~23.~
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1 by means of a- sparger 23. These bubbles flow through the venous 2 blood entering the annular trough 24 formed by the end cap 13 3 and the blood and oxygèn mixture flow upwardly through a three-4 dimensional, open cellular mixing material 25 supported above the sparger 23 within the chamber 11 by a pair of annular 6 retaining rings 26 and 27. The mixing material 25 is formed as 7 a cylinder so as to completely ~ill the cross-sectional space 8 within the cylindrical shell 12 between the annular retainin~
9 rings 26 and 27. ~
A column 30 is coaxiall~ mounted within the upright 11 cylindrical shell 12 and supported by a horizontal rod 29 form~d 12 as an integral cross brace of the annular retaining ring ~7.
13 Both ends of th~ column 30 are hermetically sealed by caps 31.
14 The top of the chamber 11 is open. The arteriali~ed blood in the form of liquid blood and blood foam rises through this 16 opening and is contained in a channel 33 formed by a generally lq half cylindrical shell 35 secured to a flat cover plate 36. As 18 described in the Canadian Patent 1,072,849, 19 supra, the channel 33 leads to a defoamer chamber 37 wherei~
20 the foam is collapsed and the arterialized whole blood collec'ed 21 and returned to the extracorporeal blood circuits.
22~ The heat exchanger comprises a pair of helically ribbed, 23 heat transfer fluid tubes 39 and 41. As shown, the hollow ribs 24 43 on these tubes have a triple helix confi~uration and provide 25 a continuous series o~ helical flutes 45. These helically 26 ribbed tubes 39 and 41 are advantageously constructed from a thin 27 wall tube of metal. Methods and apparatus for ~anufacturing such 28 helically ribbed tubes are described in U.S Patent Nos. RE24,783 29 and 3,015,355.
The heat transfer fluid tubes 39 and 41 are advantageously ~34Z3~ ~

1 formed of a continuous aluminum tube whose exterior surface 2 has been electrolytically oxidized (anodized) to produce a heavy 3 surface oxide coa-ting -to resist corrosion. The resul~ is an 4 inexpensive, reliable, and durable heat exchange element which achieves an efficient transfer of heat from the blood to the heat 6 transfer fluid, and which is compatible'with human blooa.

7 The anodization of aluminum is well known, and various 8 techniques may be employed. It has been found to be most 9` advantageous to anodize the alumi~um tube in the presen-t invention

10 with t~hat is known as a "hard coating," which is produced

11 electrolytically in a sulfuric acid bath, as per Military

12 Specification MIL-A-8625C, as amended~

13 As shown in Figures 1 and 2, the helically ribbed tubes 39 1~ and 41 are formed in a helical configuration and mounted bet~een 15 the central column 30 and the interior wall of the shell 12 16 such that peripheral portions of the ribs are closely proximate 1~ to and advantageously in contact with the exterior surface o 18 the column 30 and the interior wall 51 of the bubble ~x~gen ~9 chamber 11. One end of each of the respective tubes 39 and 41 20 passes through hermetically sealed openings 53 and 55 fo~med in 21 the bottom of the chamber 11 and the opposite ends of the tubes 22 extend through hermetically sealed openings 57 and 59 formed in 23 the cylindrical shell 35. Urethane glue provides an effective 24 sealant between the outer surface of the hard anodized tube and 25 the chamber 11 and shell 35 formed of polycarbonate plastic.
26 Shell 12 is advantageously ex-truded from polycarbonate 27 lastic and includes a longitudinal slit (not shown) such that 28 he shell may be opened up during manufacture to accept the 29 helically ribbed tubes 39 and 41. After these tubes and the 31 inner column~30 are mounted in place, the slit edges of the ' ' ~ .,,''' ` ~ ~L13~Z;3~ ~

1 shell are bonded together by ethylene dichloride.
2 Flexible conduits 61 and 63 are clamped to the upper ends 3 of tubes 39 and 41 for supplying a heat ~rarlsfer fluid, typically 4 wa~er under pressure, at the desired temperature. The lower 5 ends of the ribbed tubes 39 and 41 are connected through flexible 6 conduits 65 and 67 to a drain. In this manner, the flow of heat 7 transfer fluid is opposite to that of the flow of the blood in 8 the oxygenator chamber 11 to produce a counterflow-type heat 9 exchanger. e Since the embodiment of Figu~es 1 and 2 has many features 11 and advantages in comrnon with the other embodimants described 12 below r such features and advantages are described in detail 13 hexeinafter. A primary distinguishing feature of the emboaiment

14 of Figures 1 and 2 is the use of dual heat exchanger tubes 39

15 and ~1. The heat transfer performance of a heat exchanger is

16 related to the flo~ rate of the heat transfer fluid. Although

17 the single tube heat exchanger shown in the ernbodiments described

18 hereinafter has been found to have a most satis~actory performance

19 in all operating room environmnts tested to date~ the double

20 tube embodiment of Figures 1 and 2 would be particularly useful if

21 only very low flow rates of heat transfer fluid were available

22 during the extracorporeal procedure. -

23 Detailed Description of the Embodiment of Figures 3 and 4

24 Another embodiment of a blood oxygenator incorporating 2~ an integral heat exchanger in accordance with this invention is 2~ shown in Figures 3 and 4. In thls embodiment, the bubble 27 oxygenating chamber 70 is formed by a pair of mating plastic 28 shells 71 and 73, each including a flat perlpheral flange 75 and 29 77 which may be joined together to form a cornplete cylindrical 31 shell 80. Shell halves 71 and 73 are advantageously formed by 32 ~
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~L~L34;~3;3 1 vacuum forming or injection moldiny polycarbonate plas`tic.
2 Cylindrical shell 80 includes an upper side opening 81 and ~ a lower side opening 83 each having an integr~l outwardly 4 extending cylindrical boss 85 through which extend the respective 5 ends of a single helically ribbed heat transfer fluid tube 87.
6 The inside wall of these extending cylindrical bosses 85 and the 7 proximate exterior surface OL the heat exchanger tube 87 are 8 bonded together to effect a hermetic seal. Ethylene dichloride 9 forms an excellent bond between ~hell halves formed of polycarbona~
10 plastic. ' 11 A particular advantage of -~he construction shown in Figures 12 3 and ~ is that the heating coil 87 may be easily assembled 13 within the chamber 70. When the ribbed tubè 87 is formed into a 14 helical configuration, it has a tendency to open up, thereby 15 resulting in a certain amount of sliding f~ictional contact with `
16 the inside walls of the chamber 70 and the exterior walls of the 17 column 90 when mounted in a unitary cylindrical shell such as 18 sho~n in Figs. 1 and 2 at 12. In the embodiment of Figs. 3 and 4, 19 the interior column 90 is inserted within the helically form d 21 ribbed tube 87 and both members placed in the shell half 73 such that the two ends of heat exchange tube 87 extend through the 22 openings 81 and 8~. The mating shell half 71 is placed over the 23 heat exchanger tube 87 and the mating flanges 75 and 77 bonded 24 together to provide a completely sealed cylindrical shell unit 80.

25 As in the previously described embodiment, the peripheral portions

26 of the ribs 91 of the tube 87 advantageously contact both the

27 interior wall of chamber 70 and the exterior wall of the column 2 90.
29 A plastic rod 93 or other convenient means is affixed to 3 the opposite portions of one or both of the shell halves 71 and , : ~ :

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1 73 for supporting the interior column 90 in a ~redetermined positio 2 The mating shells 71 and 73 are necked in at their bo~tom 3 and top to form r`espective openings 95 and 97 having cylindrical 4 ~langes 99 and 101. Flange 101 snugly mates with the outside diameter o a cylindrical memher 103 on the bottom and a 6 cylindrical member 105 on the top respectively. As shown, a 7 small annular groove 107 may be formed in each of the 1anges 99 8 and 101 to accommodate an additional amount of bonding material 9 for providing a hermetic seal between the blood ch~mber 80 and the cylinders 103 and 105.
11 Three dimensional, open cellular mixing material 109 is 12 sup~orted within cylinder 103 by a pair of annular rings 111 13 and 113 attached to the inner wall of cylinder 103. This mixing 14 material completely fills the cross sectional interior of the chamber 115 along the length of the mixing material.
16 An end cap 117 is secured to and closes of the bottom of lq cylinder 103. This cap includes one or more blood inlet ports, 18 one such port 119 being connected to the extracorporeal blood ~9 circuit by a flexible venous blood conduit 121. In the center 20 of the cap 117 and extending thxough the wall thereof is an 21 oxygen inlet port 123 attached to a flexible.oxygen line 125.
22 The oxygen entering the inlet port 123 is caused to form a 23 plurality of oxygen bubbles by means of a sparger 127. These.
24 bubbles flow through the venous blood entering the annular 25 trough 129 formed by the end cap 117.
26 The upper cylinde~ 105 is secured within an opening 131 27 formed in a flat cover plate 133. The arterialized whole blood -

28 rises through tnis opening and is contained in a channel formed

29 by the cylindrical shell 35 through which i.t is passed to a . .. . .. .... .....
defoamer chamber 37 as described in the Canadian Patent 1,072,849 of 33~

:L134Z33 1 ¦P~obert 1'~1. Curtis, supra.
2 ¦ Detailed Description of the Embodiment of Figures 5, 6 and 7 31 Although the invention has been described hereinabove as al integral with a blood oxy~enator, the heat exchanger of this ~ ¦invention may be incorporated in a separate unit to be used 6 ¦elsewhere in extracorporeal blood circuits. Referring now to 7 ¦Figures 5, 6, and 7, the same type of helically ribbed heat 8 ¦transfer fluid tube 135 is mounted in a spiral configuration 9 ¦between an interior cylindrical column 137 and within a 10 ¦cylindrical chamber 139. Advantageously, peripheral port~ons 11 ¦of the riDs are in contact with the exterior of the centrally 12 ¦located column 137 and the interior wall of the chamber 139.
13 ¦AS described above with reference to the embodiment of Figures 14 ¦1 and 2, the cylinder 145 is advantageously slit along its length for facilitating insertion of the heat transfer fluid 16 tube, after which the edges of the slit are bonded together.
17 Respective end caps 141 and 143 are secured at opposite 18 ends of the cylinder 145, each with a side opening having an 19 integral outwardly extending cylindrical bosses 147 and 14~
20 through which passes one end of the heat exchanger tube 135. A
Zl suitable hermetic seal is formed between that portion of the 22 exterior wall 151 of the heat transfer flui~ tube 135 and the 23 inside wall of bosses 147 and 149 to prevent any blood leakage.
24 Typically, a suitable adhesive such as urethane glue is used to form a bond bet~een the cylinder 145 and end caps 141 and 143 26 formed of polycarbonate plastic.
27 The end cap members 141 and 143 each have a central aperture 28 153 and 155 concentric with the spirally formed heat exchanger 29 tube 135. In each such aperture, there is mounted a port member

30 157 having a ridged connector portion 159 extending outwardly

31 from the heat exchanger, four support rods 161 extending

32 inwardly into the heat exchanyer, and a through conduit 163 - :~;' :

1 throuyh which blood passes into and out of the heat exchanger.
2 As shown in Figure S, the four rods 161 make cont~ct with the 3 peripheral end surface 167 of the centrally located column 137 to retain its ends equidistant frorn the end caps 141 and 143.
In use, fle~ible water conduits 169 and 171 are attachea 6 as shown to the extending ends 173 of the ribbed heat transfer 7 fluid tube 135, conduit 171 heins connected to a suitable source 8 of heat transfer fluid under pressure. A counterflow of blood is introduced into the heat excha~ger through a flexible conduit 172 attached to the ridged connector 159. The cooled or heated 11 blood flows out of the heat e~changer through port member 157 12 into rlexible conduit 174 attached to the ridged connector 159.
13 Detailed Description of the Embodiment of Figures 8, 9a and 9 1~ Another embodiment of a blood oxygenator incorporating an inteyral heat exchanger in accordance with this invention is 16 shown in Fiyures 8, 9a and 9b. In this eI~odimen-t, the bubble 17 oxyyenator chamber 17S is formed by a cylindrical shell 177 18 having its lower end closed off by an end cap 179 having a side 19 ¦opening 181 having an integrally attached, outwardly extending 20 ¦cylindrical boss 183 formed in its outer wall and a necked-in 21 ¦portion 185 at its bottom including a cylindrical flange 187 22 ¦surroundiny a central aperture 189. This cylindrical flanye of 23 ¦the end cap 179 is sized to mate with the e~ternal diameter of 24 la cylinder 191 and bonded thereto with a suitable material such~
25 ¦as etnylene dichloride. A three-dimensionall open cellular 26 ¦mixing material 193 is supported within cylinder 191 by annular 27 Irings 195 on its underside and 197 on its upper surface.
28 ~As shown, material 193 completely fills the cross-sectional 29 ¦interior of the cylinder 191 alony the lenyth of the mixing 30 material.

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~L3423 1 I The bottom of cylinder 191 is closed off b~ a multi-port 2 end cap 199. In the ou-ter wall of the end cap 199 are formed 3 one or more blood inlet ports, one such port 201 being connected 4 to the extracorporeal blood circuit by a flexible venous blood conduit 202. In the center of the cap 199 and extending through 6 the wall thereof is an oxygen inlet port 203. The oxygen 7 entering the inlet port 203 via oxygen line 2~5 is caused to 8 form a plurality of oxygen bubbles by means of a sparger 207, 9 These bubbles flow through the venous blood entering the annular trough 209 formed by the end cap 199 and the'blood and 11¦ oxygen mixture flow upwardly through the three-dimensional, 12 ¦open cellular mixing material 193 supported above the sparger 13 1~o7 within the cylinder 191.
1~ ¦ An upright column 211 is coaxially mounted within the 15 ¦upriyht cylindrical shell 177 by a horizontal rod 123 supported 16 ¦in appropriate semicircular slots 215 formed in the top surface 17 ¦of the cylinder 191. Column 211 is advantageously formed by 18 la hollow cylindrical member 217 whose ends are sealed by 19 ¦circular discs 219, one of which is shown at the lower end.
20 ¦ The top of the cylindrical shell 177 is closed by a similar 21 ¦end cap 180 having a side opening 132 having an integrally 22 ¦attached~ outwardly extending cylindrical boss 1~4 and a 23 ¦necked-in flanged portion 186 surrounding a central aperture~ ~
24 The inner wall of flange 186 engages the outer wall of a cylindrica: .
25 member 221 whic~ in turn is attached to a flat cover plate 223.-26 As in the previous embodiments of Figures 1, 2, 3, and 4, a 27 generally half cylindrical shell 35 is secured to the top surface .
28 or the cover plate 223 for directing the liquid blood and blood 29 foam into a defoamer chamber 37.

31 The helically ribbed hea~ transfer fluid tube 225 is 32 ' ' ' .
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- -113~Z33 1 formed into a helical configuration and mounted in the space 2 between -the central column 211 and the inner wall of the cylindrica:
3 chamber 177 such that peripheral por-tions of the ribs 227 of 4 the tube 225 advantageously contact or are in very close proximity to the exterior wall of the column 211 and the interior wall of 6 the chamber 177.
7 The configuration of Figure 8 is conveniently assembled ~y 8 inserting the helically ribbed tube 225 along with the centrally 9 located column 211 into the cylindrical shell 177. As described above with referen~e to the el~odiments of Figures 1, 2, 5, 6, 11 and 7, the shell 177 is advantageously slit along its length ~or 12 acilitating insertion of the heat transfer fluid tube 2257 a~ter 13 which the edges of the slit are bonded together. As shown, the 14 respective heat exchanger tube ends will then extend above and below the shell 177. These ends are then inserted into the 16 respective openings 181 and 182 formed in the u~per and lower 17 end caps 179 and 1~0.
18 A particular advantage of this construction is illustrated 19 in Figures 9a and 9b. It has been found that after the helically formed tube 225 is inserted in the chamber 177, the tube 22.5, 21 even when manu~actured in conformance with the particular se-t 22 of specifications, does not always ultimateIy provide an 23 identical helical configuration. In particularr as noted above, 2~ there is a tendency on the part of the spirally formed ~ube.225 25 to uncoil such that it may be difficult to orient the tube ends 26 along the parallel axes as illustrated in Figure 9a. In the 27 ernbodiment shown, the upper and lower end~caps 179 and 180 may be 28 oriented along non-parallel axes as shown in Pigure 9b to 29 accommodate whatever orientation the particular heat exchanger 30 coil 225 assumes when inserted within the chal-~er 177.
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113~233 1 I Detailed Description of the Preferred Embodiment of 2 ¦ Fig~res 10 through 14 3¦ The preferred embodiment of a blood oxygenator incorporating ~ ¦an integral heat exchanger in accordance with this invention is 5¦ shown in Figures 10 through 14. In this embodiment, the bubble 6 ¦oxygenating chamber ~40 is formed by a pair of mating plastic 7 ¦shells front shell 242 and rear shell 244. The front shell half 8 12~4 includes a grooved female peripheral flange 246, into which 9 ¦fits a male peripheral 1ange 248 on the rear shell hal 24~ to lO ~form a complete cylindrical shell 250. Shell halves 242 and 244 11 ¦are advantageously formed by injection molding polycarbonate 12 ¦plastic, and may be advantageously bonded together with ethylene 13 ¦dichloride.
l* ¦ Rear shell half 244 includes a blood outlet opening 252 having 15 ¦an integral rearwardly èxtending neck 254, which i5 generally 16 ¦rectangular in cross-section. Front shell half 242 includes an 17 ¦upper side opening 256 and a lower side opening 258, each having 18 ¦an integral forwardly extending cylindrical boss 260 through 19 which extend the respective ends of a single helically ribbed heat 20 transfer fluid tube 262. The inside wall of these extending 21 cylindrical bosses 260 and the proximate exteriox surface of the 22 heat exchanger tube 262 are bonded together to effect a hermetic 23 seal. Each of the bosses 260 terminates in a tube connectar 263, 24 and redundant se.aling between the bosses 260 and the heat transfer 25 fluid tube 262 is provided by an annular sealing member 259, which 26 may advantageously include an "O" ring (not shown.) 27 As with the embodiment illustrated in Figures 3 and 4, the 28 preferred embodiment ls advantageously assembled by inserting a 29 cylindxical extruded polycarbonate plastic interior column 264 ~O within the helically formed ribbed tube 262. Both ends of the 31 ;

4Z;~l 1 ¦column 264 are hermetically sealed by end caps 265. TAe column 21 26~ and the tube 262 are placed in the front shell half 2~2 such 31 that the two ends of the hea-t exchanye tube 262 extend through ~¦ the openings 256 and 258. The mating shell half 244 is placed 51 over the heat exchanger tube 262 and the mating flanges 246 and 61 248 are bonded together to provide a completely sealed, 71 cylindrical shell ~lit 250. The peripheral portion of the ribs 81 266 of the tube 262 are closely proximate to and advantag~ously 9¦ contact both the interior wall of the chamber and the exterior wall 10 ¦of the column 264.
11 ¦ The mating.shells 242 and 244 are necked in at the bottom 12 ¦to form a hollow cylindrical neck 268. The neck 268 snugly mat~s 13 ¦with the exterior wall of a hollow, injection molded cylindrical 14 ¦member 270. A cylindrical layer 272 of three-dimensionalr open 15 ¦cellular mixing material is located in the neck 268 and extends 16 ¦into the cylindrical member 27~. The mixing material layer 272.
17 ¦completely fills the cross-sectional interior of the nec~ 268 18 ¦and is supported between an upper plurality of fingers 273, 19 ¦extending radially inward from the inner wall of the neck 268, 20 and a lower plurality of fingers 274 extending radially inward 21 from the inner wall of the cylindrical member 270.
22 The cylindrical member 270 includes one or more blood inlet 23 ports 276, one such port 276 being connected to the 24 extracorporeal blood circuit by a flexible ~enous blood conduit (not shown).
26 An end cap 277 has an upwardly extending cylindrical boss 27 278, the exterior surface of which is bonded to the interior wall 2~ of the cylindrical member 270, thus closing off the bottom of 29 the cylindrical member 270. A channel 279 is formed in the bottom 31 of the end cap 278 and extends through the side thereof to form . - ~ .

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1 ¦ an oxyyen inlet port 280 which is attached to a flexible oxygen 2 ¦ line (not shown). The oxy~en enteriny the inlet port 2~0 is ¦ caused to form a plurality of oxygen bubbles by means of a spa~ger 282. These bubbles flow through ~he venous blood entering the 5 ¦ cylindrical member 270. The sparger 282 fills the entire cross-6 ¦ section o the cylindrical member 270 and rests on the upper edge q ¦ o the boss 278. Alternatively, ~he sparger may be seated in an 8 ¦ annular groove (not shown) in the interior wall of the c~lindrical 9 ¦ member 270. In either case, the sparger 282 is sealed around 10 ¦ its periphery to the inner wall o~ the cylindrical member 270.
11 ¦ The venous blood and the oxygen bubbles then rise into the 12 ¦ oxygenating chamber 240, where they contact .the exteriar of the 13 ¦tube 262. The combination of the tube ribbing 266 and the 1~ ¦contacting suraces of the cylinder 264 ana the chamber 240 confine 15 ¦the flow of blood and oxygen bubbles substantially within paths 16 ¦o restricted area and extended length provided by the ribbing, 17 ¦thus providing a tortuous path for the blood and oxygen bubbles 18 ¦which, in cornbination with the mixing material layer 272, efects 19 la thorough mixing thereof, resulting in a substantially .complete 20 ¦transer of oxygen into the blood and removal of carbon dioxide 21 ¦from the blood.
22 The arterialized blood, in the form of blood and 23 blood oam, then 1Ows out o the oxygenating chamber through 24 the outlet opening 252 and the rectangular cross-section neck 254 25 into a defoamer chamber 284.
26 The neck 254 communicates with a rectangular opening 286 in 27 a rectangular cross-section boss 288 which is formed in the side 28 of a deoamer chamber top cap 290, which is advantageously formed 29 o injection molded polycarbonate plastic. The opening 286 in 30 turn communicates with a fluid channel member 292 located within .

32 .

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~ the top cap 290 as best shown in Fig. 13, which define~-an annular 2 defoamer inlet chamber 294.
3 Sealinqly fixed to the underside of the top cap 290 is an 4 extruded hollow cylindrical cascade column 296 which runs through a central axial void 298 in a tubular defoamer 300. The de~oamer 6 300 is contained within a cylindrical injection-moldedpolycarbonate 7 plastic defoamer shell 302 having an integral closed bottom, 8 and which is bonded hermetically around its upper periphery to 9 a downwardly extending peripheral flange 304 depending from the top cap 290. The bottom o the defoamer shell 302 includes an 11 inner upwardly concave portion forming an annular seat 308 for 12 a defoamer lower support member 309. At the inner periphery of 13 the annulàr seat 308, the bottom o the defoamer shell 302 14 extends still further upwardly to form a circular, centrally 15 raised portion 310. The support member 309 bends appropriately, 16 so as to contact the inner surface of the raised portion 310-17 forming a circular centrally raised platform 311, the inner surface 18 of which closes the bottom portion of the axial void 298 and 19 seals the bottom of the cascade column 296.

22 The defoamer 300 shown is e=sentially as described in Canadian 23 Patent 1,072,849. The defoamer 300 consists of an annular tube of 24 reticulated porous sponge material, such as polyurethane foam, 25 and is closed in a filter cloth 312 of nylon tricot or dacron 26 mesh. The filter cloth 312 is secured by nylon cable ties 314 27 to an annular upper flange 315 which extends upwardly from an 28 annular defoamer upper support member 316, which in turn is 29 bonded to a downwardly extending cylindrical boss 317 in th~ top 30 cap 290; and a lower cylindrical flange 318 extending dot~nwardly 31 _ ~7 _ ~

:~3~33 1 from the defoamer lower support member 309. Both the cloth 312 2 and ~he defoamer 300 are advantageously treated with a suitable 3 antifoam compound.
4 The arterialized blood and blood foam flow from the inlet chamber 294 into the annular axial void 298 through an annular 6 inlet 320. The majority of liquid blood entering the void 2~8 7 is guided by the column 296 to fill up the bottom of the voi~
8 298. This liquid blood flows through the defoame~ 300, as 9 generally shown by arrows 322. The blood and blood oam enter at the upper end of the defoamer ~00 so that a substantial 11 portion of the interior wall surace of the deoamer 300 is 12 contacted by a blood foam. As a result, a su~stantial portion 13 of the defoamer 300 is used to separate the blood foam from the 14 entrapped gas such that the foam collapses and ~luid blood ~lows into an annular reservoir 324 between the defoamer 300 and the 16 interior wall of the deoamer chamber 284 and settles at the 17 bottom of the chamber 284. The entrapped gas, primarily oxygen 18 and C02, which the defoamer separates out pass out o the chamber 19 284 through a vent 326 located in the upper end of the chamber a-t 20 the juncture of the top cap 290 and the cylindrical shell 302.
21 As a result, only whole li~uid blood collects in the reservoir 22 324, after having been cleaned of any particulate matter, such 23 as blood fragments and microemboli, by the filter cloth 312.
24 The oxygenated, filtered whole blood then passes through one 25 or more outlet ports 328 located in the lo~er-most portion o the 26 defoamer shell 302 and is returned to the patient by a 1exible 27 arterial conduit (not shown).
28 The defoamer chamber 28~ advantageously includes externally 29 applied indicia 330 of the volume of blood contalned therein.
30 The oxygenator may also include an externally threaded venou3 .: ` ~L~3~3~3 .P ,~

1 blood sampling port 332 proximate the venous blood inlet 276, 2 and an arterial blood sampling port 334 in the lower portion of the 3 defoamer chamber 284. One or more priming ports 336 may also be provided in the top cap 290. The ports 332, 334, and 336 are ~ conveniently sealed by screw caps 338.
6 By way of specific example, an adult blood oxygenator with an integral heat exchanger has been constructed in accordance 8 with the perferred embodiment shown in Figs. 10 through 14.
9 The oxygenating chamber 240 has ~n inside diameter of approximately three inches, while the hollow central column 264 in the oxygenatin 11 chamber has an outside diameter of approximately 1 625 inches. The 12 aluminum tubing used to form the heat exchanger tube 262 has an 13 outside diameter of 3/4 inch, which, when twisted to form the 14 helical rib 266, yields an outside diameter of approximately .65 inches from ridge to ridge of the ribbing and approximately 1~2 16 inch from groove to groove between the ribbing. The wall thickness 17 of the tube is approximately .01~ inches. The hard anodized 18 coating adds approximately .002 inches to the outside diameter 19 measurements and .001 inches to the wall thickness. When fully `
assembled, with the central column 264 and the heat exchange tube 21 262 in place, the oxygenating chamber 240 has a capacity of 22 approximately 450 milliliters.
23 A still smaller capacity oxygenating chamber 2~ employing an anodized heat exchange tubeisdisclosedin co-pending li 25 application Serial No. 317,611 filed December 8, 1978.
26 Detailed Description of the Advantages of the Invention 27 Heat exchangers constructed in accordance with this invention 28 offer significant advantages for use in extracorporeal blood 29 circuits.
One such advantage is a highly efficient transfer of heat 31 from the blood to the heat transfer fluid. This is of substantial 32 importance since the quicker the patient 1 5 blood is cooled and a .`. ....
.. ~ 33 1 rewarmed, thé shorter the time the patient has to be connected 2 to the bypass extracorporeal blood circuit.
3The efficiency of a heat exchanger normally expressed as a performance factor P/F in accordance with the following equation:

Temperature Temperature 6 P/F = Blood Out Blood In Temperature Temperature 7 H2O In ~ Blood In 8Heat exchangers constructed in accordance with this invention 9 and integral within a blood oxygenator as in the preferred embodiment of Figs. 10 through 14 consistently achievea excellent 11 perormance factors when functionally tested in vitro A series 12 of in vitro tests conducted in May and July, 197~ produced 13 performance factors ranging from ~681 to .698 for a blood flow rate 14 of two liters/minute and from .413 to .421 for a blood flow rate of 15 six liters/minute. Although early tests of units employing a 16 polyurethane-coated fluted aluminum heat transfer fluid tube tas .. . . . .. ... .. .. . . .....
17 described in Canadian Patent 1,086,714 issued September 1 ~0, 1980) showed performance factors of this order, it 19 has been found that the performance factors of production units 20 using a polyurethane-coated tube are measurably lower, although 21 still excellent as compared with prior ar~ heat exchange~s for 22 extracorporeal blood circuits. Thus, production units employing 23 polyurethane-coated hollow fIuted tubes in the same series of 24 in vitro tests conducted in May and July, 1977 and under the same 25 conditions, displayed performance factors ranging from ~503 to 26 .528 for a blood flow rate of two liters/minute and from .272 27 to .275 for a blood flow rate of six liters/minute.
28 The enhanced and consistent heat exchange performance of the 29 units embodying the anodized heat transfer fluid tube is attribute 30 to the greater thermal conductivity of the hard anodized coating~
31 ~~3~
32 ~

1~34z;~3 1 ¦ A nun~er of factors contribute to the excellen~ heat 2 ¦ transfer efficiency of ~he present invention and include ~he 3 ¦ followin~:
4 ¦ 1. The cor,~ination of the flutes of the heat transfer 1uid ~ ¦ tube and ~roximate inner and outer surface walls of the blood 6 ¦ chamber provides a plurality of continuous, restricted area flow 7 ¦ paths offering substantially uniform flow impedance to ~he ~lood 8 ¦ and blood foam. As a result, the blood and blood foam have a 9 ¦long residence time in the heat e~changer. Moreover, this 10 ¦structure avoids areas of stagnation which otherwise hinder heat 11 ¦transfer from the blood and are also undesirable from a 12 ¦physiological standpoint. In the tests conducted to date on the 13 ¦embodiments of Figures 3J 4, and 8 through 14, the blood a~d blood 14 ¦foam was observed to be in constant circulation through 15 ¦these restricted flow paths and having extensive con-tact 16 ¦with and long residence time with the heat exchanger tube.
17 ¦Only minimal areas of stagnation were evident.
18 ¦ 2. The extensive helical hollow ribs of the heat transfer 19 ¦Eluid tube provide a substantial surface area for trans-Eerring heat 20 ¦from the heat transfer fluid to the blood and blood foam. The 21 ¦tubes used in the above-described embodimtents typically have ~&
22 ¦an external surface area of the order o ~300 square inches. i 23 3. Although the direction of fluid flow through the heat 24 e~changer tube may be in either direction, the heat transfer ~
25 performance is optimi2ed by operating as a counterflow exchanger, 26 i.e., in the manner described above wherein the blood and heat 27 transfer fluid 10w in generally opposite directions~

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1 4. The wall thickness of the helically ribbed tube may 2 be relatively thin, e.g. .016 in., so as to further improve i's 3 heat transfer properties. The anodized aluminum tubes have a 4 high thermal conductivity.
S
6 5. Th~ hollow ribbed heat exchanger tube has a su~ficientl~
7 large average internal diameter, e.g.~ approximately 0.5 inch, 8 for providing a high rate of flow of the heat transfer fluid, ~ e.g. 21 liter/minute of water.
In addition to providing a highly efficient heat exchanger, 11 the helically ribbed heat exchanger tube in combination with the 12 inner and outex wall surfaces of the blood chamber has been found 13 to contribute to the oxygenation process. Thus, the blood and 14 blood foam mixture emerging from the top of the three-dimensional 15 mixing material in the embodiments of Figures 1, 2, 3, 4, 8, 16 9a and 9b, and 10 thr~ugh 14, is subjected to additional oxygen 17 transfer to the-blood and carbon dioxide removal rom the blood by lô virtue of the lengthy paths of restricted cross~sectional area 19 through which the blood and blood foam pass through the heat 20 exchanger. Tests conducted to date indicate for example that in 21 the blood oxygenators of Figures 3~ 4, 8, 9, and 10 - 14, a one-inc~
22 thick by two-inch diameter cylinder of mixing material in 23 combination with the heat exchanger accomplishes approximately the 24 same blood-gas interchange as a two-inch thick by three-inch 25 diameter cylinder of foam without the inteyral heat exchanger 26 incorporated in the blood chamber.
27 Further, the copending application, Serial No. 317,611 v/
28 filed December 8, 1978, disclosed and claims a blood oxygenator 29 in which substantially all the mixing of the blood and oxygen is 30 provided by a hollow ribbed heat exchanger tu~e in combination 32 wieh the wall surfaces. ~5 ~3~23~
1 Although the in-tegral heat exchanyer embodiments described 2 above have incorporated the heat exchanger within the oxyyenation 3 chamberr it will be apparent to those knowledgeable in the art 4 that the significant features of the heat e~changer tube which 5 contribute to its high heat transfer efficiency will be bene~icial 6 in other locations within the blood oxygenator. Thus, by way 7 of speciic example, the helically ribbed heat transfer 8 fluid tube may be located within the defoamer column such that 9 the blood flowing within or thro~gh the defoamer member is lO caused to circulate -through the flutes of the heat exchanger 11 tube.
12 The integral nature of the heat exchanger tube also provides 1~ an important advantage in providing an effective seal for 1~¦ preventing any possible contamination of the blood by the heat 151 transfer fluid. Thus, in the present invention, the heat 161 exchanger tube is advantageously constructed as a continuous 17¦ member with no connections being made to the tube within the 18¦ blood chamber. Any leak at the connection OL the heat exchanger ~91 tube and the flexible water or other heat transfer fluid conduit 211 will merely leak water or other fluid external of the blood 221 chamber.
~ In addition, the thickness of the heat exchanger tube, af~er 23 ¦formed into a ribbed configuration, is ample to Ihandle fluid pressures considerably higher than those encountered 25 ¦in clinical practice. This is important since typically the 26 ¦heat exchanger tube is connected directly to a water faucet in Ithe operating room which, turned full on, may deliver water at a 28 ¦pressure as hiyh as 60 psi. Inadvertent closing of the drain 2g ¦discharge can then build up pressure within the heat exchanger 31 to 60 psi. Such high pressures can rup-ture certain prior art I , - , I , ,, ~
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~ Z33 1 heat exchanger configurations concurrently in extensive use in 2 extracorporeal blood circuits. In contrast, in the present 3 invention, the ribbed~tubes have been tested at substantially 4 high pressures, i.e., 120 psi without any indication of structural damage or rupture.
6 In addi~ion to its excellent heat transfer characteristics, 7 the present invention is efficiently and economically manufactured.
8 Thus, the helically ribbed tube is an integral unit which may be 9 completely tested for leaks before and~or after assembly into the bl d carrying cha~ber.

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31 ~7 ..

Claims (10)

WHAT IS CLAIMED IS;

1. 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 for forming blood foam within said chamber; and second means for both (a) contributing to the transfer of oxygen into the blood and removing carbon dioxide from the blood and (b) regulating the temperature of said blood comprising:
an anodized 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 fluid conduit, said helical rib being integral with the wall of the conduit and located in contact with or closely proximate to wall means in 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 helical flute passage in combination with said wall means prior to any substantial defoamin of the blood foam and with minimal areas of stagnatior said blood and blood foam with a resulting long residence time of the blood and blood foam in contact with said heat transfer fluid conduit.

2. The blood oxygenator having an integral heat exchanger of Claim 1 wherein said heat transfer fluid conduit is a continuous length of formed aluminum tubing whose substantially entire exterior surface is electrolytically oxydized to form a hard anodized coating thereon.

3. The blood oxygenator having an integral heat exchanger of Claim 2 wherein said heat transfer fluid conduit has an overall helical configuration.

4. The blood oxygenator having an integral heat exchanger of Claim 3 wherein said wall means includes the interior wall of said oxygenating chamber and the exterior wall of a centrally located cylindrical column located within said chamber, said helically configured heat transfer fluid conduit being located between said column and said 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 hollow rib means.

5. A blood oxygenator having an integral heat exchanger comprising:
an oxygenating chamber;
means for introducing blood and bubbles of oxygen into said oxygenator chamber for forming blood foam;
means for (a) contributing to the transfer of oxygen into the blood and removal of carbon dioxide from the blood and (b) regulating the temperature of said blood, said means comprising:
an aluminum heat transfer tube whose substantially entire exterior surface is electrolytically oxydized to form a hard anodized coating thereon, said tube including heat exchange fluid inlet and outlet means and having substantially continuous hollow helical rib along its length and integral with the wall of said tube, providing a substantially continuous helical flute passage considerably longer than the length of said tube, said tube having an overall helical configuration with peripheral portions of said rib in contact with or closely proximate to a wall of said oxygenating chamber so that substantially all of said 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 blood and blood foam and formed by said helical 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.

6. An economical, disposable heat exchanger having a high performance factor which is compatible with direct contact of blood flowing in an extracorporeal blood circuit comprising:
a continuous length of aluminum tubing formed with an integral hollow rib along its length, said ribbed tube having substantially its entire exterior surface electrolytically oxidized to form a hard anodized coating thereon, said rib being located in contact with or closely proximate to wall means so that a plurality of restricted area, extended length blood flow paths around and in direct contact with the anodized exterior of said aluminum tubing are provided by said rib in combination with said wall means.

7. A blood oxygenator having an integral heat ex-changer 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 for forming blood foam within said chamber; and second means for both (a) contributing to 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:
a heat transfer fluid conduit substantially entirely composed of highly thermal conductive, blood compatible material, and including heat exchange fluid inlet and outlet means, and having rib means integral with the wall of the conduit and disposed along its length for a blood flow passage considerably longer than the length of said fluid conduit, 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 pro-duced by said first means flows in contact with the 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 blood flow passage 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 long residence time of blood and blood foam in contact with said heat transfer fluid conduit.

8. The blood oxygenator having an integral heat exchanger of Claim 7, wherein said heat transfer fluid conduit is a continuous length of metal tubing whose exterior surface is substantially entirely electrolytically oxidized to form a hard anodized coating thereon.

9. The blood oxygenator having an integral heat exchanger of Claim 8, wherein said heat transfer fluid conduit is a continuous length of formed aluminum tubing whose exterior surface is substantially entirely electrolytically oxidized to form a hard anodized coating thereon.

10. The blood oxygenator having an integral heat exchanger of Claim 7, wherein said rib means is a continuous hollow helical rib providing a continuous helical flute passage.