CA1260787A - Intraluminal membrane oxygenator - Google Patents

Abstract

THE ABSTRACT
Apparatus and method for intraluminal membrane oxy-genation of internal organs. A catheter having a walled cham-ber is introduced to dispose the chamber against the lumen an internal organ. The wall of the chamber is of a material which is freely permeable to gases, such as oxygen and carbon dioxide, and poorly permeable to liquid. Oxygen is introduced into the catheter and perfused through the walled chamber.
Oxygen passes through the wall of the chamber to the organ while carbon dioxide from the organ passes through the wall of the chamber.

Description

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TECHNICAL FIELD AND BACKGROT)ND
This invention relates to medical treatment appa-ratus and methods and more speciflcally is concerned with an intraluminal membrane oxygenator ~or use in su~taining vitality of an organ in the gastrointestinal tract.
The nature of human ~natomy is such that each indi-vidual organ's vitality is sustained by the circulation of blood through the organ's vascular system. Each organ's vascular system is of course a part of the body's larger cardio-v~s~ular system.
For any of various reasons the circulation, and henc~
oxy~en delivery, to any given organ may become insufficient to ~ustain the full vitality of that organ. For example, partial occlusion of an artery may reduce blood flow to a point where the oxygen supply is insufficient. An occlu~ion, whether ~ull sr partial, may be due entirely to naturally occurring phenom-enon or it ma~ be in consequence of certain procedures. Regard-le88 of ~he cause ~ reduced oxygen delivery csn have potentially devastating ef~ects on a patient.
As ~n example, surgica~ procedures, possibly not even directly related to a particular organ, may have an efect on the organ. For instance, in the case of certaln va~cular sur-gery procedures, it may be nece~sary to interrup~ the blood flow to æ ~iven organ or organæ during the course of procedure~.
External blood pumps may be used to supply the organ or organs during theee procedures or else ~he prooedures must be perormed with suf~icient rapidity th~t the temporary interruption o~
circulation to an organ will not produce grave consequences.
DISCLOSVRE OF INVENTION
The present invention i5 direct~d to a novel apparatus And procedure for sustaining vitality ~- an internal organ in situations such a~ these, p~rticularly with reference to ga3tro intestinal organæ. With the presen~ invention it is unnecess~ry ~o utllize external devices, such as blood pump~, ln assoclation wlth the vascular system. The pre~ent invention oEfers ~ proce-dure and appara~us which can be used at sny desired tlme, for ~L2~

example, pre-operatively, during an operation, or pos-toperatively.
One important advantage over prior techniques and apparatus is that the invention does not directly involve the cardio vascular system. Rather, the invention contemplates the introduction of a catheter into an organ of interest with vitality-sustaning oxygen being introduced through the catheter. The catheter comprises a tube having a walled chamber at one end.
The catheter is introduced to dispose the chamber against the lumen of the organ of interest. The material of the chamber is one which is freely permeable to gas but poorly permeable to liquid.
The tube contains a conduit for delivering fluid to the chamber.
Oxygen is perfused through the chamber via the tube from an external source. The external source may comprise any suitable means to create an oxygen partial pressure gradient between the interior of the chamber and the lumen of the organ whereby oxygen can diffuse through the wall of the chamber and into the organ. Carbon dioxide gas generated by the organ can also diffuse through the wall of the chamber to be conveyed back through the tube for removal.
The chamber and tube are so constructed and arranged as to create an axial flow along the interior of the wall of the chamber along substantially the full length of the chamber. This promotes the maximum area availability for delivering oxygen to an organ particularly in the case where the organ is in the gastrointestinal tract. The diameter of the chamber is less than that of the organ so that the catheter does not block passage through the organ.
The invention also contemplates the use of agents such as the use of blood and/or blood substitutes for oxygen-bearing purposes.
In summary of the above, the present invention provides an apparatus for intraluminal membrane oxygenation of an internal organ of the gastrointestinal tract independent of the vascular supply to the organ. This apparatus comprises a cathether which has a chamber on a tube, the chamber having a wall of material which is freely permeable to gas but poorly permeable to liquid.
Means are provided ~or perfusing the interior of the chamber via the tube with oxygen so as to provide oxygen to the lumen of the organ by diffusion of oxygen thorugh theiiwall of the chamber.

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yl,/sd - 2-~26~7~7 The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the sd ~ ~ -2A-.

~L~6~:)787 be~t mode contemplated at the present time in carrying out the inventlon.
BRlEF DESCRIPTION OF DRAWINGS
Fig. 1 is a view, partly schematlc, illustrating app~-5 ratus for practice of the present invention.
Fig. 2 is an enlarged transverse cross sectional view taken ln the direction of arrows 2-2 in Fig. 1 and enlsrged.
Fig. 3 is a tran~verse cross sectional view taken in the direction of arrows 3-3 in Fig. 1, Fig. 4 is a transverse cross sectional view taken in the direction of arrows 4-4 in Fig. 1 and enlàrged.
BEST ~IODE: FOR CARRYING OUT THE INVENTION
Fig. 1 illustrates a presently preferred exempl~ry embodiment of apparatus 10 for practice of the invention.
Apparatus 10 C~mprises a catheter designated by the g~neral reference numeral 12. As~ociated with catheter 12 i8 any suitable oxygen~60urce designated by the general reference numeral 14.
Catheter 12 comprises a tube 16 on the distal end of which is disposed a walled chamber 18. The opposite proxi-mal end of tube 12 is adapted for connection with apparatu~ 14.
Chamber 18 i9 provided by a tubular element having a nominal diameter greater than that of tube 1~. Fig. 1 illus-trate~ a repreMentative shape butthe invention is not limited ~o the particular shape or proportions illustrated. The tubular element 20 constitutes a membrane which forms chamber 18 and i8 fitted over the distsl end of tube 16. The opposite axisl ends of element 20 are closed onto the outside of ~ube 16 a~
at 22 and 24. In this way the chamber 18 define~ an annular 30 space 26 aro~d the ou~side of ~cube 16.
Tube 16 is a soft pliabls material, Milicone for example, which has a circular cross sec~cional shape. Tu~e 16 is provided wlth a pair of axially extending conduits, or pa~-sages, 28 and 30 respectively. These extend the full length of the tube and the cathe~er includes any suitable clo~ure means, ~ Z 6 ~

for examp~e an end closure element 32 to close off the distal end of the tube for the purpose of closing conduits 2B and 30 at that end.
Conduits 28 and 30 are communicated with the interlor chamber space 26 by means of respect1va apertureQ 34 and 36 as shown in Figs. 4 and 3 raspectively. Each aperture i8 pro-vided as a transversely extending hole from the exterior of the wall of tube 16 to intercept the corresponding conduit as shown in the drawing figures.
In use oxygen is introduced into one of the two con-duits and conveyed through tube 16 to exit the tube at the corre~ponding aperture into chamber space 26. The interior of the chamber ~pace is thereby perfused with oxygen. The oppo-site aperture provides for return conveyance of gasses via the other conduit through tube 16.
Hence, if oxygen is introduced into conduit 28, it will flow through that conduit, exit ~ia aperture 34 and pa~s into the far distal end o~ chamber space 26. The flow wlll continue axially through the annular chamber space 26 toward the proximal end of the chamber to enter aperture 36 ~nd sub sequently pass via conduit 30 back through tube 16.
If the direc~ion o~ low were to be reversed, flow through chamber space 26 would be distally, exiting tube 16 at aperture 36, passing axially through the chamber space to re-enter tube 16 at aperture 34 for return via tube 16.
In accordance with principles o~ the invention, the material of tube 20 i8 one which is freely permeable to gas but poorly permeable to liquid, so that tube 20 is a membrane. A
~uitable material is polydimethylsiloxane which is reely per-meable to oxygen and carbon dioxide gases. The o~ygen in the cathQter chamber ha~ a partial pressure so that oxygen can dif-fu~e through the wall of the chamber 18.
In use, cathete`r 12 is introduced into a patient such that chamber la i~ placed against the lumen of a hollow lnternal organ of interest. The elongate shape illustrated in Fi~. 1 i8 ~2607~97 intended for placement in the gastrointestinal tract, partl-cularly the intestines. The placement mRy be made preopera-tively or intraoperativelyl and the catheter may remaln in place even into a postoperative period.
S ~pparatus 14 i9 of any ~uitable configuration which i8 capable of perfusing oxygen through tube 16 and chamber 18 at a suitable partial pressure. For example, the apparatus may compri~e a ~tandard hospital oxygen supply givi~g a pres-sure of 760 mm.Hg. It could also alternately comprise a pump wh~ch delivers oxygen-enriched fluid. For example, the fluid may be a s~line solution which i~ pumped by the pump through the catheter with provisions being made for oxygenatlng the saline solution prior to introduction into the catheter 80 that the fluid bears a dissolved oxygen gas at suitable partial pressure.
With the wall of chamber 18 being placed against the lumen of an intèrnal organ, the flow of oxygen axially along the interior of the wall of tube 20 cr~ates a condition whereby oxygen can diffuse through the wall o tube 20 and into the lumen of the organ 80 that the catheter does not block flow through the tract. In this way, oxygen may continue to be supplied to the organ so as to sustain its vi~ality under con-ditions which o~herwise might render the organ moribund. Be-cause the org~n will also generate carbon dioxide ~as a~ a wa~te product, that waste gas can diffuse from the lu~en throu~h the wall of ~ube 20 and into the fluid which is being conveyed through chamber space 26.
The carbon dioxide gas is conveyed from chamber space 26 with the exiting fluid flow which passes proximally through tube 16 to the proximal end. In this w~y not only is oxygen made available to the organ but a wa~te product from the organ i8 also removed.
Dependin~ upon ~he degree o sophistlcation of appa-ratus 14 the carbon dioxide may be removed from the fluid and the fluid recirculated so as to form a closed system or other-. ~.

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~L%6~7~37 wise the apparatus may be an open system in which the fluidwhich returns from tube 16 i5 discarded.
In order to sustain vitality of the intestine, the P02 .of the oxygen introduced into chamber 26 must be high enough to create ~ certain gradient aeroæ~ the wall of the chamber and the lumen of the organ. In the lumen of ,a healthy intestine the P02 is about 100 mm.Hg. If the organ becomes ischemic, this figure drops to about 60 mm.Hg. Therefore, the P02 of the fluid delivered ~o the catheter should certain-ly exceed 100 mm.Hg. At the present time the use of 760 mm.Hg.
oxygen gas as the sole fluid lntroduced into the catheter ap-pear~ to be very effective. The return flow is merely exhausted.
The invention is al~o preferably practiced such th~t the material of tube 20 is not significantly stretched, or ex-panded, when in u~e, so that blockage of the pas~age through the tract may be a~oided.
The mater~al of tube 20 will b~ perm~able to mole-cules ha~r~n~ mol~cular weights o less than about 3000.. The~e-for¢, i~ i~ alæo possible to use the catheter to introducedrugs, nutrients, and/or other agents having molecular weight~
of less than about 3000.
Certain agents enhance the effectiveness of the ~ro-~ cedure. For example it is pos~ible to in~roduce lator via the catheter to enhance the local oxygenation. Iti8 al80 contempl~ted that blood or blood sub6titute~ could be used in an oxygen-bearing fluld to enhance the oxygen carry~ng capacity .
A si~nificant advantage of the in~ention i8 that it is unneceæsary to directly involve the'circulatory system for practice o the invention. Thus, the invention i9 different in principle from prior ~ascular oxygenation procedureæ which m~rely oxygenate the blood. With the invention, oxyg~n 1~
made available directly at the lumen of th~ organ. The oxygen æo delivered may be a~ tive of ~he,current vascular ~low, or ,, ~6~37l~7 it may be the ~ole source of oxygen.
The present disclosure illus~rates one preferred em-bodiment of the invention in a form which is especially useful for the intestine. O~her embodlments and forms are contem pla~ed within the scope of the invention. For example, tha catheter could be constructed with a full nasoanal extent th~ough the tract with oxygen being lntroduced at one end and the flow being discharged at the opposite end.
The invention has been shown to provide for perfusion of oxygen through a hollow internal organ o~ the gastrointesti-nal tra¢t independently of the vascular system. The oxygen 80 delivered may be assistive of current blood flow to the organ or it may be the sole source. While the invention may be prac-ticed alone, it may also be practicad in con~unction with other procedure~. The perfusion i8 accomplished w~th direct oxygen delivery to the lumen o~ the organ in a controlled manner wlthout blockag'e of the tract.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for intraluminal membrane oxygenation of an internal organ of the gastrointestinal tract independent of the vascular supply to the oxygen comprising a catheter hav-ing a chamber on a tube with said chamber comprising a wall of material which is freely permeable to gas but poorly permeable to liquid, and means for perfusing the interior of the chamber via said tube with oxygen so as to provide oxygen to the lumen of the organ by diffusion of oxygen through the wall of the chamber.

2. Apparatus as set forth in claim 1 in which said wall has permeability to allow carbon dioxide from the organ to diffuse from the lumen of the organ through the wall of the chamber for conveyance with returning flow from the chamber via the tube.

3. Apparatus as set forth in claim 1 in which said chamber wall comprises an elongate tube telescoped onto said first-mentioned tube and having axially spaced apart ends which are closed onto the outside of said first-mentioned tube, said first-mentioned tube comprising a pair of conduits extending axially therethrough, an aperture for communicating one of said pair of conduits to the interior of the chamber just inwardly of one axial end of said chamber wall and a second aperture for communicating the other of said pair of conduits to the interior of the chamber just inwardly of the other axial end of the chamber wall, and in which oxygen is conveyed through said tube via said one conduit into the cham-ber and removed from the chamber via the other conduit with the perfusion of oxygen having a flow through the chamber which is axially between said apertures.

4. Apparatus as set forth in claim ? in which the oxygen is carried in a fluid which is perfused by means of a pump connected to an end of the first tube opposite said cham-ber, said pump having an outlet connected to said one conduit and an inlet to the other conduit.

5. Apparatus as set forth in claim 1 in which the material of said chamber wall comprises polydimethylsiloxane.

6. A catheter for use in intraluminal membrane oxygenation of an internal organ independent of the vascular blood supply to the organ which comprises a soft pliable tube containing a pair of conduits, a walled chamber on said tube constructed of a material which is freely permeable to gas but poorly permeable to liquid, means for communicating one conduit to the interior of said chamber adjacent one axial end of the chamber, and means for communicating the other conduit to the interior of the chamber adjacent the opposite axial end.

7. A catheter as set forth in claim 6 including means to pump oxygen through said tube so as to cause flow axially through the interior of said chamber along the wall thereof.

8. Apparatus for intraluminal membrane oxygenation of an internal organ of the gastrointestinal tract independent of the vascular supply to the organ comprising a catheter having a closed cylindrical wall chamber on a tube with said chamber comprising a wall of material which is freely permeable to at least oxygen gas but poorly permeable to liquid, said wall adapted to be disposed in intimate contact with a lumen of a gastrointestinal organ, said tube having an entrance for pumping of fluid into said chamber and an exit for pumping of fluid from said chamber, said entrance and exit being disposed axially spaced apart along the length of the catheter and means for perfusing the interior of the chamber with oxygen, by pumping of a fluid containing oxygen in through the entrance and out through said exit so as to provide a flow of oxygen axially through the chamber and along said wall and to provide oxygen to the lumen of the organ by diffusion of oxygen through the wall of the chamber.