United States Patent Office 22693,802 2,693,802 BLOOD OXYGENATION John J. Osborn, Woodbury, N. Y. Application May 15, 1951, Serial No. 226,423 6 Claims. (Cf. 128-214) This invention relates to a method and apparatus for oxygenatinblood wherein venous blood is removed from a living animal, oxygenated, and returned to the arterial system of the animal. The apparatus may be referred to as a kind of artificial lung in which blood is spread out in a thin film, exposed to air or oxygen for a short tirne, and then returned to the body of the patient or experimental animal. According to the invention, venous blood is conducted to an oxygenating zone and deposited therein, following which it is quicyly moved, preferably during deposition, to form a layer. The moving layer is rapidly accelerated to spread the blood into a moving fflm of about 50 rnicrons' thickness and this film of blood is quickly passed through the oxygenating zone while oxygen or air is brought into continuous contact with the same, thereby oxygenating the blood. The oxygenated blood is collected and returned to the arterial system of the animal. It is essential to maintain the film of blood at a thickness of about 50 microns in order to oxygenate the blood within a reasonable period of time. For maintaining the i'ilm at the desired thickness, theacceleration imparted to the blood should be equivalent to 2 to 7 times the acceleration of @ravity. If the film is,too thick, theoxygenation is slow and thus, for satisfactory oxygenation, it would be necessary to slow down the moving film; a ,slow moving film, in turn, is apt to clot readily, requirini, the addition of an anticoagulant such as heparin or "ljicurnarol." Tle use of anticoagulants, however, is not favored in circumstances requiring the use of an artificial lung. According to the invention, it is preferred to oxygenate the blood while it is undergoing circular or rotary movement, it having been fotind that the dispersal of the blood into a film of requisite thinness, its oxygenation, and its stibseqtient collection, may be practicably controlled by virtue of subjecting the blood to rotary movement. The blood is deposited in the oxygenating zone and. qtiickly rotated to form an annular ring or layer, and this layer is rapidly spread into an inclined film having a slope iii the range of 0.5 to 6 (as hereinafter described) and a film thickness of about 50 microns by rapidly accelerating the blood along the said slope to a rotational acceleration equivalent to 2 to 7 times the acceleration of gravity. This rotating inclined film of blood is then rapidly advanced through the zone in as short a time as possible consistent with satisfactory oxygenation. Preferably, the blood is present in the oxygenating zone for a period up to two seconds. Ustially not rnore than 6 seconds are required, although oxygenation may be secured within a range of 0.25 to 15 seconds. The oxygenated blood is collected, and then, wbile still rotating, is removed from the zone and returned to the arterial system of the subject. A form of apparatus suitable for carrying out the foregoing method is shown in Figs. I and 2, wherein Fig. I is adiagrammatic, partly sectioned view of the apparattis, and Fig. 2 is a partial view taken along the line 2-2 of Fig. 1. Fig. 3 is a view like Fig. I but showing a modification. Referring to Fig. 1, the apparatus comprises an oxygenating chamber 10 having the shape of an inverted cone which may be truncated, as shown. The lower and upper ends of the chamber are open. Adjacent the lower end is a stationary inlet tube 11 above wbich is a rotatable inlet tube 12 Nvhich extends into the lower end 13 of the chamber. The tube is bent as at 14 to Patented Nov. 9 1954 2 form a lateral portion 15 which extends to a point 16 adjacent the inner lower wall of the chamber. Tube 15 terminates in an opening 17. A liquid-tight joint 18 connects the tubes 11 and 12. Means for rotating tube 12 are provided in the form of a pulley 19 attached to the til-be which is driven through a belt 20 by the puffey 21 attached to the shaft 22, the latter being connected to the shaft of motor 23. In a similar way the chamber 10 is driven by a pulley 24 attached to the downwardly 10 extending portion 25, this pulley being driven through a belt 26 by a pulley 27 d,riven by motor 23. Gear reducers 28, 29 are provided for controlling the speed of pulleys 21 and 27. Extending through the upper end 30 of the chamber is a rotatable outlet tube 31 which is 15 bent as at 32 to form a lateral extension 33 which extepds into an annular pocket or groove 34. Tube 33 has an opening 35 in communication with groove 34. A stationary tube 36 is connected to the rotatable tube through a joint 37, which is similar to joint 18, and which 20 corisists of a flange 38 on the tube 31 and a flange 39 on the tube 36. These flanges have smooth abutting surfaces and are held together by clamps, as shown at 40, inside the housing 37. Tube 31 has a movable connection with flange 38 and is rotated by means of a pulley 25 41 driven through a belt 42 by a pulley 43 on the shaft 44 of motor 45, the latter being provided with a gear reducer 46. Venous blood is introduced into the oxygenating chamber throiigh the tubes 11 and 12, The chambet is 30 first set in motion, and preferably the tube 12 is also rotated in the same direction as the chamber but at a different speed. Blood is deposited on the walls of the ch@imber and, due to the rotation, is rapidly spread into an inclined layer or film which moves upwardly along 35 the walls of the rotating chamber, the area of the film being rapidly and continuously increased as the blood adiauces upwardly. Oxygen introduced to the chamber comes in contact with the blood and oxygenates it, this phenomenon taking piace while the blood is dispersed in 40 filrn form between the poi-nt of introduction of the blood and the groove 34. At groove 34 the blood is collected and removed through opening 35 in the tube 33, the tube being rotated at a sdeed less than that of the chamber. Opening 35 points in a direction opposite the direc45 tion of spin of the chamber, and as may be apparent, the blood i)asses into the opening by virtue of its own momentum. In order to decrease the upward rate of flow of the blood as it approaches the enlarged end of the chamber and so render it more easily controllable, the upper 50 chamber wall is made more nearly vertical, -,s shown in Fig. 1, and the annlilar groove 34 is dispose,d in this vertical portion of the wall. This change in the slope occurs jtist below the groove, as at the point generally indicated at 50. The greater portion or length of the 55 wall, however, has a slope in the range of 0.5 to 6. An annular lip or flange 47 is provided on the upper enlarged end of the chamber to prevent the blood from passing over the top of the chamber. The inner surface of the chamber should be as smooth 6o as practicable to facilitate the flow of blood. As one example, a chamber made of aluminum having its inner stirface coated with paraffin gave satisfactory results. The chamber may be made of other materials, and non-wettable agents such as tetrafluoroethylene and silicone resins 65 may be used to coat the inner surface of the same. A -lass chamber coated with a silicone polymer, preferably in fli-iid form, is suitable. The flanges 38, 39 of the joint 37,- particularly the abutting surfaces of the flanges, should be made of nonwettable material. If desired, Vo these surfaces may be coated with ihe same type of nonwettable agent employed to coat the chamber 10. Of course, the flanges should have smooth abutting surfaces prior to application of any agent. The inlet and outlet tubes should also have non-wettable internal surfaces, 75 and these tubes may either be fabricated of non-wettable material, stich as plastic, or coated with a non-wettable agent of the kind described. Oxygen may be admitted to the chamber in any desired way, either to the upper enlarged end or to the So lower restricted end. Jf oile end of the chamber is closed, as it may be if desired, the oxygen may enter and leave

2,693,802 3 through the open end. Pure oxygen or air is suitable. If desired, the chamber may be placed in an incubator in which an atmospbere of oxygen is constantly maintained. The slope of the inclined film, or to say the same 5 thing, the slope of 'the wall of the char@-ib@-r, should be in the range of 0.5 to 6. That is to say, the wall of the chamber, when vewed in cross sect;on as iii Fi.-. 1, is inclined to the horizontal, a-@id the,tan-ent of the inclination an,-I-- is in the range of 0.5 to 6; or stated 10 another way, the inelination angle has a rise and a run, and the rise/run ratio is i-n the ra-,ige of 0.5 to 6.. For this purpose, the wall 6f the r-hamber, as viewed in Fig. 1, is assilmed to be straight, although actual@ly it is collvex in an outward direction. It will be noted that the 15 slope ;s positive. For purposes oj' this application, the chamber wall or the film of blood on it will be referred to as having a slope in the ran,-e of 0.5 to 6. The significance of such a sloped wall ;.s that it en--lblcs an effective dispersal of the blood to be obtained, and 20 further it aids the blood to be r@loved through the chamber, i. e , it facilitates the throughput o' blood. If the slope is too low, that is, below abrut 0.5, the - dispersal and throughput of the blood can not be very well controlled, and if the slope is too hig'@i, the blood cannot 25 be adequately dispersed. The acceleration imparted to the blood is a!..ng I"iz@ slope of the chamber wall, and as described, shou'ld be in the range of 2 to 7 times the acc-,Ieration o' gravi'@y. This acceleration is the net accelera,-ion. That is, it ".3 30 the value after s-Libtracting from the -,pplied accelera.ion the acceleration due to gravity, since in Fig. 1 the blood is moving against the action of graviiy. Accelerating the blood along the walls of the chamber is important because, as in the case of the slope, -.,'he acceleration 35 helps to disperse tle blood and to mov.-- ;t throlj,-h the chamber at a sufficient rate. If the acceleration is too low, the blood moves too slowly and rray clot; also, oxygenation is not efficient because the blood film is apt to be too thick. If the acceleration is ' oo high,! 40 damage to the blood results. As indicated, the time durinp, vihich the blood is present in the oxy.-enating zone is preferably about 2 seconds and usually not triore thati 6 seconds. ITi this range, rapid oxygenation may be accomplished while 15 avoiding clotting. Oxygenation may also be carried out employing a time range of 0.25 to 15 Recoilds. If a lower time is used, there is apt to be no apprec;able oxygenation, while if the time is too lo-@ig, clo',ting is apt to occur. A;Vith the slope of the film of b@'ood in the range of 50 0.5 to 6, and the net acceleration in the range of 2 to 7 times the acceleration of gravity, i' has been fotind th,@it the blood film will have a thickess on the order of about 50 microns, and that the blood can be advanced through the oxygenating zone within a satisfactory interval of time ind witho,,it dama@e. At a film thickness 50 of about 50 -@nicrons the oxygenation is rapid and complete and the tendency to clot is min@@'mized. Satisfactory oxygenation may be carried out at a film thic-.@-ness as low as 20 microns, so that a preferred rpnge of thick( ness is 20 to 50 microns. A blood film having a thick6 ness up to 100 microns can be handled. If the film is too thick, i. e., more than 100 microis, the oxygenation will not be satisfactory and in addition the tendency to cl6tting will be greatly increased. 6- The acceleration rpay be varied by varying the speed a of rotation of the chamber. It has been foiind that the speed of rotation need not bf, -r-ore than about 400 R@ P. M. and may be as low as 30 R. P. M. As will be utiderstood, the temperature at whic4i the oxygenation is carried out sho,,ild approximate the body 70 temperature of the patient or czperimental animal. If desired, the oxygenation of the blood may be carried out with the chqmber 10 in a reversed position. That is, tle end 13 may be the upper end instead of the lower. In this case, the blood will be introdlilr-ed to 73 the chamber in the same manner as described above and will be spread into an incliit-d layer or film on the wall of the chamber. The film in this case will move down,@vardly and will be collected in the groove 34 and removed from the chamber by means of tube 33. The riet 80 acceleration applied to the blood along the slope of the chamber will be 'the sarne as before, namely, 2 to 7 ti-(nes the acceleration of gravily. The applied acceleration will be less than that applied in the first case since in thepresent instance the blood is moving downwardly 85 4 and its movement will be aided by the acceleration of gravity. The latter value is, added to the applied acceleration so that the net@ acceleration is in the range of 2 to 7 times the aeceleration of gravity. The slope of the wall of the chamber will be in the range of 0.5 to 6, but will be a negative slope. In Fig. 3 the apparat-as comprises a plurality of nested oxygenating chambers 60, - 61, 62, 63, and 64, each having the shape of an inverted cone and each having walls that are convex i-ii an outward direction and that have a slope in the raqge of 0.5 to 6. The outermost chamber 60 is s-,ibstantially the:same as that sho-,@,7D in Fig. 1, being provided with a groove 65 and means 66 by which it may be rotated. The upper ends 67, 68, 69, and 70 of chambers 61, 62, 63, and 64 are disposed at varying heights below groove 65, and are flared so as to feed the blood either directly to groove 65 or to the wall of chamber 60 immediately below the groove from whence the blood passes to the groove. The lower ends 71, 72, 73, and 74 of @the chambers are disposed at varyin- heights above the lower res,ricted end 75 of chamber 60. Chamber 61 is spaced from atid supported on the chamber 60 by means of a series of spaced upper and lower struts, several of which are shown at 76, 77, 78, and 79. These struts may have a streamlined cross section to avoid the possibility of blood beiig obstructed by them or depositing along their edges. In a siynilar way, charnber 62 is spaced from and supported on chamber 61; chambet 63 is spaced from and suoported on chamber 62; and chamber 64 is spaced from and supported on chamber 63. As in the ca,,e of Fig. 1, a stationary inlet tube 80 is prov-ded which is connected by means of the joint 81 to a rotatable inlet tube 82, the latter having means for rotating the same of the kind described in Fig. 1. Tube 82 is provided with a number of branches 83, 84, 85, and 86, each extending to a point adjacent the inner wall of one of the chambers at the lower portion of the same. Each branch terminates in an opening for introducing blood to the chambers. At the upper end of chamber 60 a rotatable tube 87, having an inlet 88, is connected to a stationary tlibe 89 by a joint 90, by means of which blood may be removed from the apparatus in the manner described. A pump 91 may aid in returning the bj',ood to its source, or may be omitted and the blood returned tmder the force acquired by it in the oxygenating chamber. A pump may also be employed with the apparatus of Fig. 1. Essentially the operation of the apparatus of Fig. 3 is like ttiat of the apparatus of Fig. 1. In the light of the foregoing description, the following is