Catheter

Abstract

For use in administering continual spinal anesthesia, a catheter for longitudinal movement within the lumen of a relatively large needle used to approach just about to the spinal column to the end of the catheter, a thin needle with a through opening is secured and a stylet is provided in the catheter to advance the small needle relative to the large needle to pierce the wall of the spinal column in a relatively fine opening through which the anesthesia is administered.

Description

FIELD OF THE INVENTION

This invention relates to continuous spinal anesthesia; and, more particularly, this invention relates to an improved needle carrying catheter for use in piercing the spinal column wall and through which anesthesia is to be introduced as required into the column of the spine through a relatively small opening.

BACKGROUND OF THE INVENTION

In the past, it has been learned and subsequently widely recognized that there are advantages to continual spinal anesthesia in that the response to the introduction of anesthesia directly into the spinal column can produce more precise results and control. Albeit recognized however, as a practical matter, actual application of the procedure has been limited because it has heretofore been difficult to pass a needle through the back of a patient to the exact depth required for the procedure and to introduce the anesthesia through an opening small enough so that there are not attendant side effects which are very undesirable, as is explained more fully hereinafter.

OBJECTS OF THIS INVENTION

It is an object of this invention to provide an improved catheter which carries on its end a small needle and means to advance it relative to a larger needle, after the tip of the larger needle has been prepositioned near the spinal column, so that on being advanced, the small needle will pierce the spinal column wall in a fine opening sufficient for introducing anesthesia but not so large as to cause injury to the spinal wall and attendant difficulties described herein.

In accordance with this general object and purpose, the instant invention will now be described with reference to the accompanying drawings in which :

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the improved catheter;

FIG. 2 is a diagrammatic view of the first step in the process of introducing a large needle into the spine area;

FIG. 3 is a view in cross section illustrating the use of the catheter of FIG. 1 and details of its construction; and

FIG. 4 is a view of the spinal area in cross section illustrated in the affected area of the operation in which the improved catheter is employed.

DETAILED DESCRIPTION OF THE INVENTION

Continuous spinal anesthesia is a recognized, accepted and highly effective technique. This invention relates to an improved catheter for use in administering continuous spinal anesthesia. Generally, to perform the task, the anesthesic solution is introduced directly into the dura mater 8 and arachnoid using the improved catheter, to be described, which carries a relatively small needle 19 to pierce the dura wall 21. The wall is pierced by the smaller needle after the extradural space 10 has been reached by a larger needle 12 by advancing the smaller needle carried by the catheter. This is done in the following manner.

First, an appropriate interspinous vertebral space is selected; the surrounding skin is scrubbed with an antiseptic solution and dried completely; and anesthesia of the skin and soft tissues performed. The extradural space 10 is reached with a straight relatively large needle 12, preferably about 15 gauge, with a stylet in place. To the extent possible the bevel 13 of the needle is presented in longitudinal position, for an easier pass through the skin and supra-spinous and interspinous ligaments 14. When the characteristic major resistance of the flavum ligament 15, between the extra dura 10 and the zone 14 is perceived, the stylet, not shown, is removed and the distal end of the big needle is connected to a specially treated, very sensitive, small, 2 cc. syringe of glass filled with air, not shown.

The extradural space 10 on the proximal side of the flavum ligament 15 is reached in the following manner. The needle 12 is very gently advanced or introduced while with the other hand an effort is made to force the penetration of the air in the syringe through the needle. The introduction of air will be unsuccessful until there occurs the penetration of the needle through the favum ligament 15 and penetration begins into the extradural space 10. This will be recognized because, when the extradural space is reached, there will be a sudden lack of resistance which is characteristic of this area contrasting to the resistance offered by the flavum ligament. The lack of resistance confirms that the extradural space has been reached. It is also confirmed because, when the extradural space is reached, the air of the syringe is introduced easily and rapidly and, simultaneously, there occurs a sudden inversion of the resistance against removal of the big needle. This is sometimes referred to as the double inverted resistance sign; in other words, the resistance given by the flavum ligament 15 is overcome and the negative pressure which characterizes the penetration to the extradural space is sensed.

As shown in FIG. 2, once the extradural space 10 is reached by the tip of the 12, the improved catheter 17, shown in FIG. 1 and to be described hereinafter, is introduced through the lumen 18 of the needle 12, with a stylet 16, see FIG. 3, in place in the catheter 17. A firm and quick pressure is then applied to the catheter 17 by means of the stylet 16 which will cause a small needle 19 on the end of the catheter to penetrate the dura wall 21 and enter the dura mater 8 and arachnoid, reaching the subarachnoid space. Thereafter, the stylet 16 is removed. Then, a syringe is connected to the distal end of the needle carrying catheter and a gentle suction is made until the CEF, or spinal fluid, is obtained, confirming the location of the tip of the small needle. The anesthetic solution, which is ready in another syringe, may then be introduced directly into the dura through the catheter in intermittent injections of the anesthetic solution any time it will be needed during the surgical procedure.

It will be helpful to refer to FIG. 3 at this juncture in summary of the procedure. The extradural space 10 between the flavum ligament 15 and the dura wall 21 is reached by a relatively big needle 12; and the location of the tip or bevel 13 of the big needle is sensed in the manner described above. The catheter 17 is inserted through the column 18 of the needle 12 and the wall 21 of the dura is penetrated by a small needle 19 fixed on the tip 20 of the catheter. A preferred embodiment of the small needle carrying catheter will now be more particularly described with reference to FIG. 3 and FIG. 1.

The catheter 17 is composed of a plastic catheter tube 31 of suitable length, which may be similar to a urethral catheter in consistence and calibration and of about 20 gauge. To the tip 20 of the catheter tube 31, a thin needle 19 of about 25 gauge is secured with the needle extending beyond the tube end about 0.5 centimeter, which corresponds for the purposes described above to the extradural and dura space cross sectional dimension and with the catheter and needle being sized so as to be able to pass through the column of the big needle, which is preferably 15 gauge.

Means are provided to secure the smaller needle 19 to the tube; in the embodiment shown the means are as follows. In the plastic wall 31 at the tip 20 of the catheter the surface of the proximal end 33 of the needle 19 is provided with a key surface or pattern in relief 33 to join it to the tube, i.e., the needle is embedded in the tube wall. It will be seen that the lumen 37 of the needle is characterized by converging side walls 39 to the distal end 41, which has an opening or mouth 43.

In use, through the center or column 45 of the catheter 17 the stylet 16 is passed; it has a terminal end of a dimension greater than the mouth 43 of the needle, but less than the inside diamter of the catheter tube, so that, when a longitudinally directed force is applied to the stylet, its leading edge will bear against the inside wall 37 of the needle for use in driving the relatively small needle 19 through the dura wall and into the dura mater.

It is thus seen that the above described needle carrying catheter provides a means for introducing anesthetic solution into the dura through a small opening relative to that which would be made if the big needle were advance through the dura wall, which heretofore, when done has been attendant with great disadvantage because of an increase in the rate of postanesthesia sequalae from the relatively large perforation of the dura wall, dura mater and arachnoid. Because of the relatively large perforation caused by a large needle, in the past, direct introduction of anesthesic solution directly into the dura has been limited to a relatively small number of patients denying to others the recognized benefits of continuous spinal anesthesia introduced directly into the dura which has been widely recognized to have special advantages but for the injury to the dura wall, etc., as explained above. In summary, this invention provides a catheter for subarachnoid anesthesia adopted for wide application in surgery. It will be seen that the catheter comprises a tubular length of plastic material of a diameter small enough to be passed through a larger needle of appropriate size for passage through the skin and supraspinous and interspinous ligaments, including the flavum ligament, which catheter has fixed to its leading end a thin needle which is used to extend through the mouth of the larger needle and is used to pierce the dura wall in a small perforation when advanced using a stylet, or introducer, sized for longitudinal movement of advance through the catheter to bear against the inside wall of the relatively small needle to advance it and the catheter and penetrate the dura wall, which stylet can then be removed for the introduction of anesthetic solution directly into the dura or subarachnoid space through the column of the catheter. In the preferred embodiment means are provided on the inner end 51 of the stylet 16 to coact with the wall of the needle. The means of the embodiment shown are simply the inner end of the stylet being sized so as not to pass through the opening of the small needle but rather to bear against the walls which converge to the tip to apply an advancement force. Other types of mutually intercooperating means may optionally be provided to interconnect the stylet and the catheter. Also, the outer end 61 of the catheter stylet may be provided with means 63 to aid in advancing the catheter, the preferred embodiment including a plastic body 65 having an enlarged outer end and a somewhat smaller end in which the outer end of the stylet is captivated by suitable means.

Claims

What is claimed is:

1. A spinal anethesia administering apparatus comprising in combination, a first big needle defining a lumen and a catheter sized for longitudinal movement removable received in the lumen of said big needle, said catheter including, a tubular length having a first end zone and a second end zone and of a diameter smaller than the lumen of the big needle,

a thin needle portion on the first end zone of said tubular length having a through passageway and a distal end portion having a tissue wall piercing tip and a proximal end portion and with said through passageway being in fluid transmitting engagement with said tubular length,

an elongated stylet having a first end and a second end and with said first end in said tubular length and with said second end being exterior of said tubular length, and said stylet being of a length greater than said tubular length and being sized for longitudinal coaxial movement in the tubular length and being sized less than said through opening in said thin needle portion, and mutually inter-co-operating means on the first end of the stylet and said thin needle for applying a longitudinal force to advance the thin needle and tubular length relative to the big needle after said big needle has been utilized to penetrate to a predetermined depth for a second stage of penetration by said thin needle, whereupon the stylet may be removed from said combination and material be injected through said tubular length and thin needle.

2. The combination as set forth in claim 1 wherein the interco-operating means on the first end of the stylet and said thin needle comprise walls included in said thin needle converging to a constricted opening at the distal end, said opening being of a diameter greater than the diameter of the first end of said stylet and the diameter of said stylet being less than the span between the walls of said thin needle at its proximal end to bear against the wall of the needle for advancing movement of the catheter relative to the big needle when longitudinal force is applied to the stylet.

3. The catheter as set forth in claim 1 wherein the catheter is of about 20 gauge size, the thin needle is of about 25 gauge size and the longitudinal dimension of the small needle is about 0.5cm.

4. The catheter as set forth in claim 1 wherein means are provided securing the proximal end of the thin needle to the first end zone of the tubular length and said means comprise an annular recess in the first end zone of said tubular length and said end zone is of plastic material and a pattern in relief on the proximal end of the needle is provided and said pattern is disposed within said recess and imbedded in the plastic material of said tubular length, with said pattern in relief keying the needle and tubular length together as a unitary piece.

5. The combination as set forth in claim 4 wherein the intercooperating means on the inner end of the stylet and catheter comprises walls included in said thin needle converging to a constricted opening at the distal end of a diameter greater than the diameter of the first end of said stylet and the diameter of said stylet is less than the span between the wall of said thin needle at its proximal end to nest between the walls and thin needle ends and to bear against the needle for advancing movement when longitudinal force is applied to the stylet.