CA1225896A - Methods and apparatus for intravenous therapy and hyperalimentation - Google Patents

Abstract

21314 Foreign METHODS AND APPARATUS FOR
INTRAVENOUS THERAPY AND HYPERALIMENTATION
ABSTRACT
Methods and apparatus for short term and long term intravenous therapy including hyperalimentation are disclosed. The proximal end of a flexible catheter having a one way valve adjacent its proximal end is inserted through the skin of a patient and into a vein having a suitably large flow of blood therethrough.
The distal end of the catheter has a threaded male coupler for connecting it to a flow reducing adaptor and thence to a source of intravenous solution. The solution flows by gravity through the catheter and into the vein. A passer which can be connected to the male coupler is provided for subcutaneously threading the catheter during long term catheter placement.

Description

21314 foreign ~L225~6 The present invention relates to the intra-venous administration of nutrients and therapeutic agents to patients and, more particularly, to methods and apparatus for administering intravenous hyperalimentation.
Ingestion, digestion, and absorption of food and assimilation of resulting substrates into the body cell mass are vital functions of the gastrointestinal tract.
These functions may be impaired in a variety of ways. For e~ample, infants born with ~as~rointestinal abnormalities, adults who develop gastrointestinal diseases, burn or accident victims, cancer patients, etc., may be unable to maintain their nutritional and fluid balance by oral intake. Without proper trea-tment they may die from starYation and dehydration.
Traditional intravenous feeding, i.e., through relatively small veins in the li~bs, has severe limita-tions. A patient with one of the above described maladies may initially require eight liters or more of intravenous fluid per day with enough fats, proteins, and carbohy-drates to meet the bodyis nu~tritional requirements andmaintain positive nitrogen balance. Beyond three liters per day, however, the excess fluid strains the cardio-vascular system. A diuretic may be given so that the kid-neys can process the additional fluid. However, this method is dangerous.
Another approach is to increase the concentra-tion of nutrients in the intravenous solutions. However, such solutions cannot be dripped into a relatively small vein in the arm or lég without severe pain coupled with the risk of vein inflammation and/or thrombosis.

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21314 foreign ~2~
In the early 196()'s Dr. S-tanley J. Dudrick and his colleagues developed a method of intravenous nutri-tional support (referred to in the medical profession as a hyperalimentation or total parenteral nutrition) by which normal growth and development as well as a positive ~itro-gen balance could be maintciined. An open ended catheter was threaded through a moderate sized vein such as the subclavian, accessible under the collarbone, and into a very large vein, the superior vena cava. Because of the very lar~e flow of blood through the superior ~ena cava a concentrated solutior! deli~e:red through the catheter is rapidly diluted, thus allc~ing administration of a high concentration of nutrients without risk of pain, venous inflammation, or thrombosis.
Since Dr. Dudrick's initial work extensive research and development has been done with intravenous nutritional solutions. It has been possible to supply up to 7000 calories per day intravenously. Different appa-ratus and methods have evolved for short and long term intravenous therapy. With the latter, the distal end of the catheter is routed subcutaneously to an exit point midway down the anterior wall of the chest. The patient can then couple the catheter to a source of nutrients in the home and thus avoid prolonged hospitalization while still obtaining in-tensive intravenous nutritional therapy.
Serious problems heretofore encountered with hyperalimentation include pol,entially fatal air embolism which may occur when the distal end of the catheter be-comes disconnected; severe or fatal hemorrhage which 21314 foreign ~LZ~B~

may also occur if the end of the catheter becomes discon~
nected; and blood reflux into the open proximal end of the catheter which may result in blood clots which inter-fere with and stop the flo~ of intravenous solution through the catheter. These clots may also form the nidus for bacterial or fungal growth which may then give rise to serious or fatal septicemias. If blood clots from the catheter enter the circulatory system the consequences may be serious or fatal. Therefore, it has been necessary to flush out the catheter with an anti-coagulant as often as every four hours.
In order to avoid metabolic disorders due to excesses or deficiencies in the administration of intravenous nutritional therapy it is necessary to control the amounts of nutrients and fluids supplied.
Heretofore, every known apparatus for intravenous hyper-alimentation has utilized costly pumps and flow sensing devices for controlling the rate of fluid administration, both to prevent too rapid administration which would result in severe metabolic disorders, and to prevent flow stoppage which may result in clottiny in the catheter, making it unusable. A photoelectric sensor or some other device must be used to shut off the pump when the solution bottle has emptied otherwise a serious and possibly fatal air embolus ~will occur. ~f the pump is non-operative for just a short period of time, blood will reflux into the open proximal end~of the catheter, causing a blood clot which ~ay render the catheter inoperative or lead to other previously described com-plications.

21314 ~oreign ~2~5~3~3!6 Other problems involve the amount of hardwarewhich must remain coupled t:o the distal end of the catheter after insertion. This inhibits the patient's mobility and increases the .risk of accidental dislodg-ment, kinking, or cutting o:f the catheter. Furthermore, if intravenous therapy is temporarily suspended, the ca-theter must be flushed with an ant.icoagulant solution as frequently as every four hours to prevent blood clots from forming in the catheter. F:inally, methods of passing the catheter through the subcutaneous tissue for permanent placement have been cumbersome and require separate tunnelling and threading procedures.
Catheters with one way valves adjacent their closed proximal ends have been used to deliver cerebro-spinal fluid to the atrium of the heart. However, cathe-ters with proximal one way valves have not heretofore been utilized to accomplish intravenous administration of nutrients or therapeutic aglsnts, including total parenteral nutrition.
Summary of t~le Invention It is an object o.l- the present invention to provide methods and apparatus for intravenous aclministra-tion of nutrients or therapc-~utic agents, includinc~ total parenteral nutrition, that ~7ilI substantially eliminate any risk of loss of blood through the catheter as well as problems resulting from the~formation Orc blood clots inside or outside the cathel.:er.
It is another obj~i~ct of the present invention to provide methods and apparatus for~intravenous admin-istration of nutrients and 1:.herapeutic agents, including 21314 foxeign total parenteral nutrition, which will reduce the incidence of infection in, on, or around the catheter.
It is another object of the present invention to provide methods and apparat~ls for administration of nutrients or therapeutic agents, including total parenteral nutrition, that will substantially reduce the risk of air embolism.
I~ is a further object of the present inven-tion to provide methods and apparatus for intravenous administration of nutrients or therapeutic agents, including total parenteral nutrition, which do not require pumps and other comple~ flow control devices.
It is yet a further object of the present inven~
tion to provide methods and apparatus for intravenous administration of nutrients or therapeutic agents including total parenteral nutrition, such that any equipment used to insert the catheter, other than the catheter itself, can be easily and completely removed after insertion of the catheter.
It is another object of the present invention to allow intermittent temporary ter.mination of intra-venous therapy, including total parenteral nutrition, with - disconnection from the sourcle of intravenous therapy.
without the danger of catheter occlusion by blood clots and without the need for repeated flushing with heparin or other anticoagulant substances.
It i5 yet another ~?bject o~ the present invention to allow determination of the venous pressure, preferably in the superior vena cava (central venous pressure) of the vessel the cstbeter tip :is posit~one~ in without :

~ 9 ~ 3198-897 allowing blood reflux into the catheter and without the need for additional apparatus or manometers.
It is a further object of the present invention to allow easy subcutaneous passage of the catheter utilizing a passer which can be readily connected to the distal end of the catheter and used to simultaneously form a subcutaneous tunnel and thread the catheter therethrough.
The apparatus according to the present invention comprises a flexible catheter having a closed end adapted to be inserted in a vessel of a patient and a valve adjacent such end.
The opposite end of the catheter is open and has a male coupler secured thereto. A passer is provided for threading the catheter subcontaneously in a patient, the passer including an elongated tube adapted to slide over the male coupler and the open end of the catheter, a sharp tip adapted to be releasably connected to one end of the tube, and means releasably to attach the coupler to the tip.
According to the present invention the proximal end of a ~lexible catheter having a one way valve or valves adjacent its ~0 proximal end is inserted through the skin or through a surgical incision in the skin of a patient and into a vein having a suitable large blood flow therethrough. The catheter preferably has a coating of heparin or other anticoagulant substance on its internal and external surfaces, radiopaque markings and metric indicia, and a removable internal stiffener. The distal open end of the catheter has a male threaded fitting or coupIer which is threadably coupled to a flow reducing adaptor which is, in turn, ;~ .r ~2~ 6 coupled to a source of in~ravenous fluid having the desired concentration of nutrients or kherapeutic agents, via a standard intravenous drip connector. A11 extraneous apparatus necessary for the insertion of the catheter is easily removed after insertion. The intravenous solution flows by hydrostatic pressure through the catheter and into the vein, the maximum flow rate bein~ limited to a safe level by the valve and by the flow reducing adaptor. The venous pressure inside the vein (venous pressure) is easily determined by finding the fluid pressure at which flow just stops and subtracting the opening pressure of the catheter valve or valves. The 21314 foreign iD5jl~9~

catheter may be intermittently disconnected from the source of intravenous fluids and capped without danger of blood clots forming in or on the catheter. A tubular passer can be readily connected to the male coupler at the distal end of the catheter and used to simultaneously form a subcutaneous tunnel and retrogradedly thread -the catheter therethrough.
Brief Description of the Drawings Fig. lA is a fragmentary view of -the catheter forming a part of the short term intravenous therapy apparatus of the present invention. Shown in Fig. lA are the removable internal stiffener and the threaded male coupler at the distal end of the catheter which threadably engages the flow reducing adaptor;
Fig. lB is a fragmentary view of the catheter forming a part of the long term intravenous therapy ap-paratus of the present invention. The one way valve at the proximal end of the catheter is shown open or expanded which occurs when 1uid inside of the catheter is a-t a pressure sufficiently greater than that outside of the catheter. Also shown in Fig. lB is the cuff which surrounds the catheter and is imbedded in the subcutaneous tissue near the point where the catheter exits the body Fig. 2A shows the,flow reducing adaptor which is threadably engaged with the male coupler at the distal end of the catheter. A cap may be screwed over the distal end of the adaptor to seal the same;
Fig. 2B shows the standard male fitting of an intravenous drip mechanism ;inserted into the distal end of the adaptor;

-7~-21314 foreign ~2~5B9'6 Fig. 3A shows a hypodermic needle and a sleeve which fits over the same, both forming part of the short term intravenous therapy apparatus. The hypodermic needle hub accepts the male fitting of a standard syringe;
Fig. 3B shows a fragmentary view of the catheter of Fig. lA being guided through the sleeve of the short term intravenous therapy apparatus with the aid of the internal stiffener;
Fig. 4A shows a ragmentary view of the passer forming a part of the long term intravenous therapy apparatus;
Fig. 4B shows the manner in which the passer of Fig. 4A is connected to the distal end of the catheter of Fig. lB;
Figs. 5A-5D are simplified anatomical views of a patient illustrating the manner in which the short term intravenous therapy or hyperalimentation apparatus is utilized; and Figs. 6A-6H are simplified anatomical views of a patient illustrating the manner in which the long term intravenous therapy or hyperalimentation apparatus is utilized.
Description of the Preferred Embodiments The term 'prox1mcll end' when used in reference to a needle, sleeve, or catheter, refers to the forward end thereof which is inserted into the patient's body.
The term 'distal end' when used in reference to a needle, sleeve, or catheter, refers to the rearward end thereof which is situated externally of the patient's body.

~ Accordlng to the present invention, -the apparaius 2131~ foreign ~2~
utilized to perform short term intravenous therapy or hyperalimentation has certain mechanical elements in common with the apparatus utili~ed to perform long term intravenous therapy or hyperalimentation. Specifically, both preferably include a flexible catheter having a one way valve or valves adjacent its proximal end, internal and external coatings of heparin or other anticoagulant substance, radiopaque markings and metric indicia, a male threaded coupler at the distal end of the catheter, a l~ removable internal stiffener, and a flow reducing adaptor which threadedly engages th~_ male coupler at the distal end of the catheter and which accepts the male itting of a standard intravenous d:rip mechanism at its distal end~
and may threadedly accept a cap at its distal end when intravenous therapy is temporarily interrupted. In addi-tion, the short term intravenous therapy apparatus includes a syringe, needle, and external sleeve which are hereafter described. The long term apparatus includes a passer and a DACRON (trademark) cui-f which is hereafter described.
Referring to Fig. lA, the catheter 10 which is to be inserted into the patiLent is made of a durable flexible, biocompatible material such as, but not necessar-ily, silicon rubber. One suitable material is sold under the registered trademark SI]~STIC. Preferably the catheter is translucent so th~t the physician can determine the presence of ai.r bubbles within the catheter. When used for short term intravenous ther~py, the catheter preferably has sufficient length to extend from the skin of the pa-tient to a vein~which will not be adversely affected by the intravenous ther3p. or therapeutic agent administered.

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2131~ ~oreign :~ ~2~ 6 In the case of administration of concentrated hyperali-mentation fluids, this length should be sufficient to extend from the site of insertion to the superior vena cava. The length will depend upon the size of the patient and the intended therapy to be administered. When used for long term intravenous therapy or hyperalimentation, the catheter preferably has sufficient length to extend from the superior vena cava to the deltopectoral groove or anterior lateral neck and further to a point midway down the anterior wall of the chest.
The catheter must have a relatively small outside diameter so that it can be readily inserted into a vein, such as the subclavian vein, without causing undue trauma to the vein and the surrounding tissues. Preferably the catheter has an outside cliameter no greater than four millimeters. The inside diameter of the catheter mus-t be large enough to permit intravenous solution to flow there-through at a rate sufficient to allow the required amount of nutrients or therapeutic agents to be delivered. An example of a suitable size is an outside diameter of 2.2 mm and an inside diameter of 1.3 mm~
The catheter has a one way valve 12 (Fig. lA) adjacent its proximal end. The valve may be ~ormed by one or more individual slits precisely cut into the catheter wall. Multiple slits may be circumferentially spaced. As shown in Fig. lB, the valve :L2 opens when the fluid pressure inside the catheter is greater than the fluid pressure outside the catheter by a predetermined amount.
The minimum amount of pressure needed to open the valve may be varied from catheter to catheter by varying the .

21314 foreign ~225B~36 number of slits, length of the slits, the thickness of the catheter wall, or the elasticity of the catheter wall.
A catheter with this type of one way valve will resist retrograde flow of fluids into the proximal end of the catheter. That is, when the hydrostatic pressure inside the catheter is greater than the pressure outside the ca-theter by a given amount, the opening(s) defined by the slit(s) 12 will expand ~Fig. lB), thereby allowing fluid to flow out of the catheter. However, when there is fluid pressure outside the proximal end of the catheter which is greater than the fluid pressure inside the catheter, the valve opening(s) will close and prevent retrograde flow into the catheter. One suitable catheter is the PUDENZ
~trademark) cardiac catheter manufactured by Heyer Schulte, Inc., a subsidiary of American Hospital Supply Export Corporation. It is available in several different valve opening pressures.
The catheter preferably has a coating 13 of anti-coagulant substances, such as sodium heparin, on its internal and external surfaces to prevent the formation of blood clots thereon. The suri-aces defined by the slit(s) 12 should preferably be coated in this manner to prevent blood clots from form1ng on the valve openings(s).
The proximal end 14 (Fig. lA) is preferably pointed to facilitate insertion and advancement of the catheter in the vein. It may contain a quantity~of radio-paque materlal 15, such as barium~sulfate, so that the position of the proximal end of the~catheter within the patient can~be determined by x-ray. Alternatively, the entire catheter may be impregnated with a radiopa~ue ., --].1--, ~1314 foreign 5~ 6 material. The catheter preferably has indicia in the form of a metric scale 17 which can be observed by the physician to determine the extent to which the catheter has been inserted.
The distal end of the catheter is open. An externally threaded, tubular male coupler 16 is tightly se-cured in the open distal end of the catheter. Preferably the coupler 16 is glued in place -to prevent its accidental dislodgement. To facilitate insertion of the catheter into a vein a removable stiffener 18, such as a stainiess steel wire, may be positioned in the catheter during insertion and removed through the open end of the catheter after the catheter is installed.
Referring to Fig. 2A, the coupler 16 is adapted to be threadably engaged with the internally threaded proximal female end of a tubular flow reducing adaptor 20.
Adaptors with different flow red~cing characteristics are available. The adaptor 20 has an internal fitting 21 with a small flow reducing orifice typically in the~range of 16 to 27 gauge. The distal end of the adaptor 20 is fashion~d to be coupled to the standard male fitting 22 (Fig. 2B) of an intravenous drip mechanism. The flow reducer is additionally threaded on its distal external surface so as to threadably accept a cap 24 (Fig. 2A) which may be utilized when no intravenous fluid therapy is being administered.
When the catheter lS being used for long term therapy the intermediate section oE the catheter may have a surrounding cuff 26 (F1g. lB) made of a fabric material such as that sold under the registered~trademark DACRON. As ' 21314 forelgn ~L2~5~
shown in Figs. 6G and 6H the cuff 26 is placed on the long term catheter such that it will be located in the subcu-taneous tissue under the skin where the catheter 10 e~its from the body.
Referring to Fig. 3A, a standard syringe 28 has a needle 30 preferably with a coating 32 of TBFLON
(trademark). A tubular sleeve 34 has an inside diameter slightly greater and a length slightly less than that of the coated needle. The sleeve can be slipped over the coated needle and the proximal end of the needle will be exposed (Fig. 5A). As shown in Figs a 3B and 5C, the catheter 10 is guided through the sleeve 34 and into the vein with the aid of the internal stiffener 18.
; Referring to Figs. 4A and 4B, the passer includes an elongate tube 36 adapted to slide over the male coupler 16 and the distal end of the catheter 10. The passer also has a tubular tip 38 having a sharp forward end. The rearward end of the tip has a cylindrical hub 40 with internal threading for threadedly engaging the malecoup-ler 16 and external threads f~r threadedly engaging internal threads in either end of the tube 36.
When the catheter is to be installed on a short term basis, e.~., for a period of roughly three weeks or less, the following method may be utilized. A
clearer understanding may be had by reference to Figs.
5A-SD. With the patient in the lying position a vein whlch has been chosen in which to insert the catheter is dilated as much as possible, either by applying a proximal tourniquet or~positioning the patient in a~

head down position so that the vein fills by hydrostatic 21314 foreign ~L~2~ 6 pressure.
Veins with a suitably large flow of bloodtherethrough and which are readily accessible include -the cephalic, subclavian, internal jugular, external jugular, basilic, and median cubital veins. The skin over the vein is surgically prepared in the usual manner. Local anesthetic may be lnjected around the area of insertion.
Referring to Fig. 5A, the needle 30 fitted to the syringe 28 is inserted into the tubular sleeve 34.
The proximal ends of the needle and sleeve are inserted through the skin and advanced until the proximal ends of the needle and sleeve enter the desired vein. The plunger of the syringe is slightly withdrawn. If blood is readily drawn into the syringe, the physician can be reasonably sure that the ne~edle 30 and the sleeve 34 have entered the vein. The sleeve is then advanced slightly, held firmly, and the needle is withdrawn from the sleeve (Fig. 5B). The physician o;bstructs the distal end of the sleeve, e.g., with his i~r her finger, in order to stop the flow of blood therefrom. Prior to insertion of the catheter, which preferably has the internal stiffener 18 in place, it is filled with intra~enous solution to elim-inate air from its interior. The solution will not flow out the proximal end of the catheter through the one way valve 12 without a pressure head supplied by the solution in an IV bottle yreater than the valve opening pressure.
At this point the catheter is preferably not connected to the IV bottle. ~
Referring to Flg. 5C, the proximal end of the catheter 10 is inserted through the sleeve 34 into the 21314 foreign ~2Z5~

chosen vein, e.g. the subc]avian, and advanced an appro-priate distance as requirecl by the type of intravenous fluids to be administered. Next, -the sleeve 34 is slid out of the patient and over the distal end of the catheter (Fig. 5D)~ If an internal stiffener 18 had been used it is withdrawn at this time (Fig. 5D)~ The flow reducing adaptor 20 is then threadably secured to the threaded male coupler 16 at the distal end of the catheter (Figs.
6G-6H). The male fitting 22 of the IV drip mechanism is then secured to the distal end of the flow reducing adaptor 20 and the solution flows from the IV bottle solution through the drip m~_chanism, through the flow reducing adaptor, through the catheter, out the one way valve and into the vein.
It is also possib;Le to insert the catheter into the patient without filling the catheter with intravenous solution before insertion. The one way valve at the catheter tip will remain closed during the insertion and prevent air from flowing through the catheter and causing an air embolism. Once the catheter is in place a syringe partially filled with intravenous ~olution may be used to aspirate air from the catheter. The catheter may be fully injected with the intravenous solution in the syringe prior to coupling the flow reducing adaptor tc>
the drip mechanism and the bottle of intravenous solu~
tlon.
When the cathstsr is in correct position it is secured to the skin nsar its point o insertion. This may be accomplished by sutures snd/or bandages. Proper loca-tion of the proximal end of the catheter is preferablyconfirmed by x-ray.

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21314 foreign ~2~

When long term int:ravenous therapy or hyperali-mentation is contemplated, e.g. for periods ranging from three weeks to several months or longer, the fol]owing method may be utilized. Referring to Fig. 6A, the patient is put in the supine position; the shoulder and desired catheter exit point prepared for surgical inci-sion by shaving and scrubbing with antiseptic solutions.
Sterile surgical drapes are applied to isolate the area of the deltopectoral groove and -the desired catheter exit point. Local anesthetic is injected intradermally and subcutan:eously in the area of the proposed incision, the path of the subcutaneous tunnel, and the proposed cathe-ter exit site. An incision is made through the skin and the subcutaneous tissue dissected to reveal -the cephalic vein. Again, other readily accessible veins, such as the jugulars or subrlaviarl, which empty into the superior vena cava, may be utilized depending on cir-cumstances.
Control of the vein is obtained by means of ligatures, clamps, or other means. The proximal end of the catheter is inserted into the vein such as the cepha-lic, either directly through an incision in the vein or via the hypodermic needle 313 and~external sleeve 34 as previously described. The proximal end of the catheter, preferabIy with the internaL stiffener 18 in place, is advanced into the superior ~ena cava. Proper location of the catheter is determined by x-ray as previously de-saribed. A ligature is tie~iaround the cephalic or other vein distal to the point at which the catheter enters the vein. The internal stiffener, if present, is then re-; -1i5-- ~

2131~ foreign ~225~39~

moved (Fig. 6B). Another ligature is tied around the cephalic or other vein and cclthe-ter to anchor the position of the catheter in the vein, Referring to Fig. 6C, the male coupler 16 at the distal end of the catheter ic; inserted through the tube 36 of the passer and is threadedly secured to the tip 38 of the passer. The tip is in turn threadedly secured to the distal end of the tube 36. Referring to Flgs. 6D
and 6E, the physician grasps the passer and threads it subcutaneously from the incisio~ in the shoulder to an exit point substantially midway down the anterior wall of the chest or some other selected location on the pa-tient. The passer is guided through the skin at the exit point. The proximal portion of the catheter is firmly held at the incision in the shoulder while the passer is pulled to draw slack portions of the catheter through the subcutaneous tunnel. The passer, with cathe-ter attached, is pulled until the cuff 26 of the catheter is located subcutaneously near the opening in the skin at the ,exit poin-t.
Referring to Fig. 6F, the tip 38 of the passer is unscrewed from the tube 36 and from the male coupler 16. The tube 36 is slid off the catheter over its distal end (Fig. 6G). Air in<,ide the catheter is aspir-ated with a syringe and the catheter is filled with an intravenous solution as prev:iousLy described. The male coupler 16 is threadedly engaged with the flow reducing adaptor 20 which in turn is connected to the male itting 22 of the drip mechanism coup:Led to the IV bottle. A1-ternatively, a cap 24 may threaded1y~engage the distal .

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2131~ foreign ~.2'~S~

end of the flow reducing adaptor 20. The catheter is secured to the skin near the exit point with sutures and/
or bandages. The incision in the shoulder i6 closed.
The intravenous nut:rient or therapeutic so-lution flows by gravity from the solution bottle through the flow reducer and catheter and into the vein. The flow is driven by the hydrost:atic pressure deriving from the position of the bottle of intravenous solution in relationship to the tip of the catheter within the pa-tient. The maximum f low rate! is restricted to a safelevel by a flow reducing ada~tor connected to the distal end of the catheter. Further control is provided by the specific opening pressure of the one way valve. When the bottle of intravenous solution is empty, there is no longer a pressure head sufficient to keep the one way valve open and thus the risk of air embolism is substan-tially eliminated. The one way valve at the proximal end of the catheter prevents retrograde flow of blood into the catheker and the problem of blood clotting in the ca~
theter and thus stopping the intravenous solution flow is substantially eliminated~ It is no longer necessary to have continuous flow of fluid through the catheter to prevent clot formation, nor is it necessary to periodi-cally flush out the catheter wlth anticoagulant sub-stances. This device thus eliminates the need for costly pumping and flow control devices and eliminates one of the major hazards of systems requiriny such devices.
Even if the distal~end of the catheter becomes :
uncoupled, the patient cannot lose blood through the catheter because ;the one~way valve closes in the absence :

21314 ~oreign ~225~96 of internal fluid pressure. Furthermore, the risk of air embolism in such cases is minimal since air cannot travel through the closed end of the catheter without being under pressure.
The presence of an anticoayulant coating on the surface of the catheter prevents the formation of blood clots on the inside or outside of the catheter which might impede intravenous solution flow, serve as a nidus of bacterial growth leading to bacterial septisemias, or serve as a source of septic emboli when the catheter is withdrawn.
It is easily possible to measure the patient's central venous pressure without aIlowing reflux of blood into the catheter and without the use of additional manometers or other equipment. This is done by determin-ing the vertical distance be!tween the fluid level in the bottle of intravenous solution and the proximal tip of the catheter at which flow through the catheter just stops or starts. The opening pressure, which is known, of the one way valve at the catheter tip is substracted from this value to give the venous pressure outside the tip of the catheter. When the catheter tip is in the super-ior vena cava this value is the central venous pressure to a clinically accurate value.
The apparatus utilizes a minimum number of components. The sleeve of the short term catheter apparatus can be completely removed from the patient, thus reducing ex-traneous hardware~ and the hazards associated therewith. A passer can readily be coupled to the distal end of the long term catheter and allows for simultaneous 21314 foreign :~Z~5~

subcutaneous tunneling and threading of the catheter to an exit site on the anterior chest wall.
The distal end of the long term catheter can be readily manipulated by the patient because of its con-venient location, i.e., micLway down the anterior wall of the chest or other suitable site. This arrangement is desirable because it allows the patient to self~administer nutrient or other therapeutic solutions on an inter-mittent basis.
As shown in Fig. 6H, upon completion of a particular infusion the cat.heter may be filled with an anticoagulant solution and the cap 24 threadedly connected to the distal end of the fluid flow reducing adaptor.
The patient now has the freedom to ambulate without the constraint of an infusion apparatus connected to him/her.
The patient may avoid prolonged hospitalization by con-veniently self-administering nutrient or other therapeu-tic agents, including total parenteral nutrition, on an intermitten~ basis outside the hospital.
Having described the preferred embodiments of the invention, it will be apparent that the invention permits modification in arrangement and detail.

Claims (4)

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

1. An apparatus for performing intravascular therapy including hyperalimentation comprising:
a flexible catheter having a length sufficient to extend from a vessel in a patient having a suitably large flow of blood therethrough and through an exit site in the skin of the patient, the catheter having a valve adjacent its proximal end;
a male coupler secured to the open distal end of the catheter, and a passer for threading the catheter subcutaneously, the passer including an elongate tube adapted to slide over the male coupler and the distal end of the catheter, a tip adapted to be releasably connected to the forward end of the tube, and means releasably to attach the distal end of the catheter to the tip.

2. An apparatus as set forth in claim 1, said catheter having a valve adjacent its proximal end.

3. An apparatus as set forth in claim 1, wherein said tip is provided with a sharp edge for cutting a passageway through the body tissue of a patient to enable the passer to be passed subcutaneously beneath the skin of a patient whereby after emergence of the tip from the skin and removal of the tip from said tube, said catheter may be advanced within said tube, and said tube may be withdrawn from the body by sliding the same over said catheter leaving the catheter within the passageway formed by the passer beneath the skin of the patient.

4. The apparatus of claim 1 or 2, wherein said tip is threadedly engaged to said coupler and to said tube.