Arterial infusion catheter

Abstract

A catheter for prolonged infusion of medication into an artery. The catheter has a unique tip design employing the flap valve principle to assure uniform and steady diffusion of the medication into the bloodstream and also to inhibit retrograde flow of blood into the catheter thereby minimizing clotting and the resulting blockage of the medication flow.

Description

BACKGROUND OF THE INVENTION

In the care and treatment of hospitalized patients, catheters of various types are used to carry out the necessary treatments. Some catheters are used for drainage, some for infusion and some for both purposes. Also, depending upon the particular treatment, the catheters may be used for either short term or prolonged treatment. In the area of regional intra-arterial infusion, catheters are used to inject or infuse medication into the bloodstream. For example, in certain malignant tumors, arterial catheters are used for the regional infusion of chemotheraputic agents over prolonged periods. Thus, once the catheter has been inserted, it can be fixed in place and utilized for continuous infusion or for periodic infusion over prolonged periods. In this manner, the trauma of repeated punctures and re-insertions of the catheter can be kept to a minimum. However, in using prolonged intra-arterial infusion several difficulties are encountered. Quite frequently, the blood will clot around the distal end of the catheter and cause premature cessation of the treatment. Also, with arterial catheters of presently known design, there is an inadequate mixing of the medication with the bloodstream which results in sporadic and unpredictable drug levels at the sight of the lesion. When clotting around the end of the catheter occurs resulting in blockage of the flow of medication, the catheter must be withdrawn, cleaned and reinserted. Since clotting is unpredictable, the infusion process must be closely watched so that cessation of the flow of medication can be quickly detected and corrective action taken. Thus, patients receiving medication through intra-arterial infusion must be closely watched and if problems result the patient quite often must suffer the trauma of withdrawal and re-insertion of the catheter a number of times during the course of the treatment. It is a principal object of my invention to overcome these disadvantages of prior art catheters so that more effective treatment can be accomplished with a minimum of trauma and pain to the patient.

SUMMARY OF THE INVENTION

The invention provides a catheter design in which the distal end inserted into the artery is provided with a flexible portion containing one or more slits which serve as valves. When positive pressure is applied to start the infusion process, the slits will open and allow the medication to enter the arterial flow of blood. During the time that positive pressure is being applied, clotting cannot occur to block the flow, and if the positive pressure is withdrawn the slits will close to shut off the flow of medication and inhibit the retrograde flow of blood into the catheter thereby preventing blockage of the catheter. Also, with the multiple valve design of the catheter, and using positive pressure to inject the medication, greatly improved diffusion of the medication into the bloodstream is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a portion of an artery, partly in section, and showing a catheter employing the principles of the invention in place in the artery;

FIG. 2 is a perspective view of the end of the catheter and showing the valves in a closed position;

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2;

FIG. 4 is a perspective view similar to FIG. 2 but showing the valves in an open position;

FIG. 5 is a sectional view taken on the line 5--5 of FIG. 4;

FIG. 6 is a perspective view showing the tip of a catheter employing the principles of the invention as disclosed in another embodiment thereof; and

FIG. 7 is a view similar to FIG. 6 but showing the valves of the catheter of the second embodiment in an open position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

In FIG. 1 there is shown in section the wall 10 of an artery 12 in which the flow of blood is in the direction indicated by the arrows. In employing the technique of intra-arterial infusion, the artery in punctured by a suitable instrument (not shown) and then the tip of a catheter 14 is inserted to the desired depth and with its distal end 16 pointing downstream. The catheter 14 consists of a cannula or hollow tube 18 the proximal end 19 of which is attached to a source of medication (not shown). By force of gravity or other means of applying a positive pressure, the medication flows through the tube 18 and is discharged through the distal end 16 into the bloodstream.

At or near the distal end 16 of the catheter 14 the tube 18 is provided with a plurality of cutout portions or windows 20 which are formed in between connecting ribs 22 that interconnect the tube 18 and the distal end 16 of the catheter 14. Each of the windows 20 is covered with a material having a modulus of elasticity less than the material from which the tube 18 is made. Formed in the material covering each of the windows 20 is a plurality of cuts or slits 24 which provide valves through which fluid introduced into the catheter 14 may be discharged. As best seen in FIGS. 2 and 3, when the pressure inside of the catheter 14 is approximately that of the blood in the artery 12, the valves 24 will be closed thus preventing both the flow of medication from the catheter 14 and retrograde flow of blood into the catheter 14. However, when the pressure applied to the medication in the catheter 14 is slightly greater than the blood pressure, the valves 24 will open, as best seen in FIGS. 4 and 5. Opening of valves 24 allows the medication of flow outwardly through each of the valves 24 and into the bloodstream of artery 12. Because there are a plurality of valves 24 provided around the entire circumference of the catheter 14 near its distal end 16, this allows the medication to be discharged uniformly and evenly thus providing greatly improved diffusion of the medication into the bloodstream and eliminating sporadic and unpredictable drug levels at the injection site. If the prolonged treatment requires repeated, regular injections of medication for limited periods of time, the catheter 14 is left in place, and the positive pressure applied to infuse the medication is stopped after each injection and the valves 24 will close preventing the retrograde flow of blood into the catheter 14. With prior art devices, the blood in the artery 12 would tend to clot at the site of the lesion sometimes even during treatment, and would start to clot immediately after treatment was discontinued if the catheter was left in place. The invention eliminates these problems by allowing the catheter 14 to be inserted and left in place during the entire time of the treatment without clogging even though the treatment may be quite prolonged.

In FIGS. 6 and 7 there is shown another embodiment of the invention, and parts corresponding to those of the first embodiment will be referred to by the same reference numeral followed by the latter a. Thus, in the second embodiment, the catheter 14a includes a cannula or tube 18a having a distal end 16a. At the distal end 16a of tube 18a there is provided a valve tip 30 which is formed of a material having a modulus of elasticity less than the material from which the tube 18a is formed. The valve tip 30 is affixed to the distal end 16a in any suitable manner and completely encloses the otherwise open end of the tube 18a. Formed around the periphery of the valve tip 30 are a plurality of slits or valves 24a. In FIG. 6, the slits or valves 24a are shown in a closed position which is their condition if the pressure inside of the catheter 14a is approximately that of the blood inside of the artery 12. In FIG. 7, the valves 24a are shown in an open position which will occur if the pressure applied to the medication inside of the catheter 14a is greater than the blood pressure in the artery 12. The second embodiment of FIGS. 6 and 7 has all of the advantages and features of the first embodiment, the only difference being that the catheter 14 of the first embodiment has a distal end 16 of a relatively hard material thus facilitating insertion. On the other hand, the catheter 14a of the second embodiment has a soft easily deformable valve tip 30. In either case, the insertion technique is the same with the catheter being inserted immediately after the artery wall 10 is punctured with a suitable instrument.

A catheter employing the principles of the inveniton is of tremendous benefit in any procedure requiring the prolonged infusion of medication into the arterial tree either continuously or periodically over a prolonged time. Also, a properly designed catheter employing the principles of the invention may be used for intermittent intravenous administration of all types of medications including such techniques as the scalp-vein heparin lock technique. It will be obvious to those skilled in the art that a variety of techniques and treatments can be employed with a catheter made according to the principles of the invention.

I have described my invention in connection with two preferred embodiments thereof. It will be obvious to those skilled in the art that the materials used in the catheter can be of any suitable material, it being important only that the valve portion have a modulus of elasticity less than the cannula. the number, size and actual placement of the slits which form the valves can be varied as will be obvious to those skilled in the art. Obviously, catheters can be built according to the invention in various diameters with various specified rates of flow, the rate of flow being a function of the infusion pressure, the modulus of elasticity of the valve segment, the thickness of the valve segment, diameter of the catheter and number and size of the slits forming the valves.

It will be further obvious that various revisions and modifications can be made in the specific preferred embodiments disclosed herein without departing from the spirit and scope of the invention. It is my intention, however, that all such revisions, modifications and uses will be included within the scope of the following claims.

Claims

I claim:

1. A catheter for use in arterial infusion of fluids and the like, said catheter comprising a cannula formed of a material sufficiently rigid to facilitate insertion thereof into an artery, said cannula having a distal end and a proximal end, a part of said cannula at the distal end having a plurality of cutout portions spaced around the circumference of said cannula and separating said distal end from the main body of the cannula, said cutout portions being separated by ribs extending longitudinally between the main body of said cannula and its distal end which ribs are formed integrally with said cannula, a flexible material extending completely over each of said cutout portions along the inside surface of said cannula and having a modulus of elasticity less than the modulus of elasticity for the material which forms said cannula, the flexible material covering each of said cutout portions having a plurality of slits therein to provide for discharge of fluid from inside of said cannula through said slits when the fluid pressure in said cannula exceeds the pressure on the outside of said cannula which preventing the retrograde flow of fluid into said cannula regardless of the pressure difference between the inside and outside of said cannula.

2. The catheter of claim 1 in which there is at least one row of slits in the flexible material covering each of said cutout portions, the said row extending longitudinally along the cutout portion, and said cutout portions extend around the entire circumference of said cannula between said ribs.