US 3630198 A
Description (Le texte OCR peut contenir des erreurs.)
United States Patent 3/1963 Hunter 10/1967 Foderick ABSTRACT: A catheter placement device including a Teflon catheter with an imperforate, generally hemispherical tip and two laterally opening ports adjacent the tip, the catheter being telescoped onto a cannula which bears against an annular internal shoulder behind the tip and communicates with the ports. The device is gripped by handles attached either directly to a hub on the cannula or to an adapter releasably connected to the hub, and is inserted through a shallow incision made with a disposable introducer formed in one piece with a troughlike pointed shank and an integral grip which centers the thrust of insertion on the shank. A capillary tube and a syringe are included as alternative sensing devices for communicating through the cannula with the ports to determine when a change in condition occurs during placement.
PATENTED UEC28 ran SHEET l U? 3 IN VEN TOR. M51. v m1 1. //A/A //v CATHETER PLACEMENT DEVICE BACKGROUND OF THE INVENTION This invention relates generally to catheters and, more particularly, to the placement of catheters in body cavities, passageways and potential spaces for the passage of fluids through the catheter, either the withdrawal or drainage of fluid from the body or the administration of fluid to the body.
I-Ieretofore, the placement of catheters typically has been accomplished with the assistance of a sharply pointed needle for piercing the body tissue. For some procedures, the needle itself serves as the catheter through which fluid is passed, while in other instances, a small-bore internal catheter has been threaded through the bore of a needle into the body, or a larger-bore catheter has been externally positioned on a needle for introduction as an incident to the insertion of the needle. In the latter type of placement units, the needle point protrudes from the tapered leading end of the catheter to pierce the body tissue in advance of the catheter, thereby leading the catheter through the tissue to the selected body cavity or potential space.
Where a sharply pointed needle leads the catheter through the body tissue into, or close to, the ultimate position of the inner end or tip of the catheter, there is a distinct danger of inadvertent puncturing of delicate tissue and organs disposed in the path of the needle but beyond the intended area of penetration. For example, for epidural anethesia, a catheter is inserted into the spinal structure through the interspinous ligaments and the bordering ligamentum and into the epidural space, wherein the point of the needle is very close to the dura. If there is a very slight misjudgment, a dural puncture can occur, with serious results for the patient. There are many similar situations, well known to those skilled in the art, in which the use of sharp needles in the placement of conventional catheters involves a danger of inadvertent and harmful punctures.
SUMMARY OF THE INVENTION The present invention resides in a relatively simple and inexpensive catheter placement device which eliminates the need for a needle for leading the catheter into its final position, which also may be forced with relative ease and control through body tissue, and which provides a ready indication of the arrival of the catheter at the desired position before there has been excessive penetration. More specifically, the preferred embodiment of the invention includes a disposable catheter that is composed of low-friction plastic material and is telescoped over a longitudinally stiff cannula, the catheter being formed with an imperforate tip that covers the leading end of the cannula and is shaped for blunt dissection of tissue. The interior of the cannula communicates through the tip with at least one port that opens laterally out of the catheter adjacent the tip, and the leading end of the cannula bears against an end wall of the catheter behind the tip. For application of the force required to drive the catheter through the tissue to be penetrated, the trailing end of the cannula has a hub with means enabling the user to maintain a firm grip thereon.
To provide a prompt and reliable indication of the entry of the tip into a body cavity, the hub of the cannula also has a seat for attachment of a sensing device, e.g., a capillary tube or a syringe, operable to indicate a change in fluid condition at the tip of the catheter, and thus to signal the entry of the ported portion of the catheter into a body cavity. The grip and sensing device may be mounted directly on the cannula hub, or may be mounted on a special adapter seated against the hub.
To facilitate initial insertion of the catheter through the skin and to aid in directing it toward the body cavity, the invention includes a novel, disposable introducer for making an incision in the skin and guiding the placement device through the tougher outer tissue layers into the underlying softer tissue. The introducer is of simple construction that may be mass produced at relatively low cost with a sharp and effective point, and has a novel grip for more effective application of the thrust of insertion so as to eliminate torque tending to bend the introducer during use. Accordingly, the introducer is an easily fabricated and inexpensive tool which is disposable after use, and yet is highly effective for its intended purpose, as compared with prior instruments designed for the same general purpose.
Other objects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged side elevational view of a catheter placement device embodying the novel features of the present invention, with part of the central portion broken away for compactness and part shown in cross section for clarity;
FIG. 2 is an enlarged fragmentary cross-sectional view of the tip and the adjacent portion of the device, taken substantially along the line 2-2 of FIG. 1;
FIG. 3 is a view similar to FIG. 2 with the cannula removed;
FIG. 4 is an enlarged cross section taken along the line 4-4 of FIG. 1;
FIG. 5 is a fragmentary perspective view illustrating the insertion of the introducer through the skin;
FIG. 6 is a view similar to FIG. 5 with the catheter placement device positioned for insertion along the introducer;
FIG. 7 is a fragmentary sectional view taken in a plane extending longitudinally of the device and showing the device as it is inserted along the introducer into a body cavity;
FIG. 8 is an exploded view similar to FIG. 7 after the introducer and the cannula have been removed from the patient and the catheter, respectively;
FIG. 9 is an enlarged fragmentary view, partly in cross section and partly in side elevation, showing a modified form of the invention with handles and a capillary tube incorporated in the hub of the cannula;
FIG. 10 is a view similar to FIG. 9 showing a second modified form with a detachable connector releasably coupled to the hub of the cannula and to the barrel of a syringe for communicating through the connector and the cannula with the tip of the catheter;
FIG. 11 is a view similar to FIG. 10 in which a capillary tube has been applied to a detachable connector;
FIG. 12 is an enlarged perspective view of the introducer;
FIG. 13 is an end view thereof;
FIG. 14 is a side elevation thereof including a fragmentary view of a grinding wheel for sharpening the point;
FIG. 15 is a plan view;
FIG. 16 is a plan view of a substantially fiat blank prior to bending and sharpening of the blank to form the introducer; and
FIG. 17 is an enlarged cross-sectional view taken substantially along the line l7l7 of FIG. I6.
DETAILED DESCRIPTION As shown in the drawings for purposes of illustration, the invention is embodied in a device, indicated generally by the number I0, for use in inserting an elongated, tubular catheter 11 through body tissue 12 (FIGS. 5-7) until the inner end portion or tip 13 of the catheter is disposed within a body cavity 12,, (FIG. 7) for the eventual passage of fluid through the catheter 11 into or out of the cavity, as determined by the particular medical treatment being provided for the patient. Examples of the use of catheters are epidural anesthesia, in which the anesthetic is passed through the catheter into the epidural space, paracentesis of pericardial effusion, in which fluid around the heart is withdrawn through a needle serving as a catheter; and cerebral ventricular drainage, in which liquid is drained through a catheter placed in a ventricle of the brain. There are, of course, many other well-known uses of catheters, and including drainage of the bladder, the chest, the abdominal cavity, and subcutaneous wounds.
As previously mentioned, the usual practice has been to use a sharply pointed needle to pierce or cut through the body tissue preparatory to insertion of the somewhat flexible catheter through the tissue, whether the catheter is carried on the outside of the needle to be left in place after the needle is withdrawn, or is small enough to be threaded through the needle into place prior to withdrawal of the needle over the catheter. In some instances, a pointed, hollow needle is used not only to pierce the tissue but also to draw fluid from the body cavity. Where the catheter is externally disposed, it is desirable to use a catheter that is either composed of or coated with a low-friction material like tetrafluoroethylene, obtained commercially under the trademark Teflon of E. I. duPont de Nemours Co., Inc.
In any event, safe placement of a catheter is a body cavity in a conventional manner with a pointed needle that cuts through the tissue, requires very careful handling of the needle to avoid penetration to an excessive depth, beyond the desired end point for the catheter. The sharp point of such a needle passes through the body tissue so quickly and smoothly as to give virtually no indication of the type of tissue being penetrated, and thus can pass through the wall of a cavity and puncture delicate tissues beyond the wall before the user realizes the point of the needle has entered the cavity.
In accordance with a primary aspect of the present invention, the catheter 11 is formed with an imperforate tip 13 shaped for blunt dissection of tissue, and is telescoped slidably onto a longitudinally stiff cannula 14 which has a leading end 15 for pressing against an inside abutment surface 17 behind, and closely adjacent, the catheter tip 13, to drive the latter through the body tissue. At least one port 18 opens laterally out of the catheter adjacent the tip and communicates reliably with the interior 19 of the cannula when the latter is in the catheter. A hub 20 is provided on the outer or trailing end of the cannula with means thereon for applying the inserting force to the cannula, and thus to the tip of the catheter, and also for attachment of an appropriate sensing device or indicator communicating through the cannula with the port or ports adjacent the tip of the catheter.
With this arrangement, the resiliently flexible catheter 11 is driven through the body tissue by the force applied through the cannula 14 to the abutment surface 17 immediately be hind the tip 13 so that the catheter sheaths the cannula, and the blunt tip of the catheter actually leads the cannula through the tissue and into the body cavity. Because the tip is blunt, there is sufficient resistance to movement to provide a perceptible variation as the tip moves into a cavity, giving the user a feel" for the progress of the tip, and the blunt catheter penetrates the tissue atraumatically, without the cutting action that is characteristic of a sharpened needle. In addition, no stylet is required to close the port or ports 18 in the catheter, and the interior of the catheter thus remains constantly open to the port or ports for fluid passage through the catheter to the sensing device.
In the present instance, the cannula 14 is simply a flat or blunt ended, hollow needle (see FIG. 8) having a hub 20 of basically conventional construction at its outer or trailing end, the lower end as viewed in FIG. 1 and the right end in FIG. 8. The interior of the needle forms an internal passage 19 extending from the leading end completely through the hub. When the placement device 10 is fully assembled, the catheter 11 is telescoped onto the cannula and covers the latter from the tip to the hub, preferably having a hub 21 on its trailing end in abutment with the leading side 22 of the cannula hub 20.
It will be seen in FIGS. 1-4 that the catheter 1 l is formed by a relatively thin-walled tube, preferably of circular cross section, defining an internal passage 23 which extends from the abutment surface 17, adjacent the upper end of the catheter in FIGS. 1-3, through the catheter to the hub 21 thereon. Through the hub, the passage 23 communicates with a seat 24 in the side of the catheter hub abutting against the cannula hub 20, the seat being formed in the trailing side of the catheter hub in relation to the direction of insertion. This seat preferably is tapered to receive a conventional tapered fitting (not shown) for connecting an instrument or conduit to the catheter after it is placed and the cannula 14 has been removed.
Catheters are made in different' sizes, depending upon the requirements of the particular treatment and ranging, for example from l/l6 of an inch outside diameter, or smaller, to /4 of an inch or larger. For a general appreciation of the illustrative embodiment, the outside diameter may be considered as being on the order of 1/16 of an inch, thus being shown approximately full size in FIGS. 6-8. The cannula 14 has an outside diameter selected to fit within the catheter with a snug, sliding fit.
As shown in FIGS. 2 and 3, the tip 13 is disposed across and closes the leading or upper end of the internal passage 23 of the catheter, has an imperforate, outer leading side that is shaped for the blunt dissection of tissue, and has an inner trailing side extending transversely across the leading end of the passage 23 and forming the abutment surface 17 for engagement with the transverse end surface 15 of the cannula. Preferably, the leading side of the tip is generally hemispherical, and the transverse surfaces 15 and 17 are generally perpendicular to the longitudinal axis of the catheter.
As shown most clearly in FIG. 1, two laterally opening ports 18 herein are formed on opposite side of the catheter 11, immediately behind the tip 13, at the opposite ends of a crosspassage 25 in the tip, and a third port or passage 27 (FIGS. 2 and 3) extends through the central portion of the abutment surface 17 into the center of the cross-passage to establish communication between both ports 18 and the internal passage 19 in the cannula 14 when the latter is in place in the catheter. The connecting port 27 has approximately the same diameter as the inside diameter of the cannula, and is coaxially centered with respect to the cannula and the catheter.
Thus, the abutment surface 17 is any annular internal shoulder surrounding the connecting port 27 and having approximately the same radial width as the radial wall thickness of the cannula. It will be noted, however, that the end surface area of the cannula has been utilized advantageously for the application of driving force through the shoulder 17 to the tip 13, and that the cannula and the connecting port are maintained positively in full communication with each other without regard to any changes in the relative angular positions of the parts.
Although the cross-passage 25 may be made concentric with the curvature of the leading side of the catheter tip 13, the cross-passage of the preferred form of the catheter is offset slightly toward the leading side relative to its center of curvature, as is most readily seen in FIGS. 2 and 3. This reduces the amount by which the tip projects beyond the end 15 of the cannula and correspondingly reduces any tendency the tip may have to bend over during penetration. In addition, the width of the tip longitudinally of the cross-passage 25 is increased slightly, as shown in FIG. 1, to thicken the tip to an almost rectangular cross section with rounded corners. This strengths the tip and assists in keeping the ports 18 generally in longitudinal planes nearly parallel to the longitudinal axis of the catheter 11.
For ease of fabrication, the body of the catheter may be a shrinkable Teflon tube that is shrunk around a mandrel, and the tip 13 may be meltable Teflon that is fused to the end of the tube and shaped between the mandrel and a suitable die (not shown). These and other procedures are within the skill of the art.
It will be seen in FIG. 1 that the trailing end portion of the catheter 11 is telescoped over a tubular flange 28 of the catheter hub 21, and is anchored in an annular recess 29 of the hub. This is merely an illustrative manner of attachment of the catheter to its hub, and it will be evident that various other mountings may be used. The catheter hub 21 simply abuts against the cannula hub 20, and does not interlock therewith. When a nose 30 is formed on the cannula hub as shown in FIGS. and 11, this nose may fit loosely into the tapered seat 24 of the catheter hub, but should not be locked therein.
The means for gripping the placement device 10 and applying the inserting force through the cannula 14 to the tip 13 of the catheter l1 herein comprise two winglike handles 31 projecting in opposite directions from the cannula hub 20 and rigidly secured thereto. These handles may be grasped between the thumbs and forefingers of two hands during placement of the catheter, and provide for convenient application of the force required to insert the catheter. As shown herein, the handles are the opposite end portions of a single, elongated plate of metal or suitably rigid plastic material that is secured to the leading end of the cannula hub.
To facilitate the proper placement of the catheter 11 in a patient, the invention contemplates the use of a novel disposable introducer 32 (See FIGS. 5-7) for making an initial incision through the skin and other outer tissue layers, and guiding the catheter through these layers into the softer inner layers of flesh. In general, the introducer comprises an elongated troughlike shank 33 terminating at one end in a point 34 for making the incision and having a grip 35 on the opposite end portion with which the introducer is held as the point is pressed through the skin and into the position shown in FIGS. 5-7.
With the introducer 32 thus inserted, the leading end portion of the catheter placement device 10 is placed in the upwardly opening trough or groove defined by the shank 33, and is slid along the shank through the incision and into the patient. If desired, a light downward movement of the introducer may be used to open the incision slightly to admit the catheter.
Initially, the force required to move the placement device 10 will be slight, because of the preparatory incision made with the introducer which, it will be seen, is inserted a distance considerably less than the full depth to which the catheter is to be driven. After the catheter tip 13 passes the point 34 of the introducer, the resistance to penetration increases substantially since the tip then is forced bluntly through the imperforate tissue.
Although the resulting resistance to penetration is perceptible, it is not so high as to make the placement difiicult, and the use of Teflon or the like reduces the frictional drag on the catheter to a negligible amount. Accordingly, relatively firm insertion pressure is all that is required for the blunt dissection of underlying tissue, and the variations in resistance in going through different types of tissueincluding muscle, fascia, ligaments and other connective tissue, and the walls of organs such as the urinary bladder-are not significant. The tip of the catheter is shown in FIG. 7 as being disposed just inside the wall 37 of the body cavity 12a.
After serving its purpose of making the initial incision and directing the catheter 11 into the patient the introducer 32 is removed as indicated in FIG. 8. When the tip 13 of the catheter 11 has been advanced to its intended final position, the cannula 14 also is withdrawn as shown in FIG. 8, leaving the catheter ready for connection to a syringe or other instrument for the intended treatment.
The modified placement devices 10a, 10b and 10c partially shown in FIGS. 9-11 illustrate various ways in which sensing devices may be incorporated in, or connected to, the cannula of the placement device to provide a ready indication of a change in condition at the tip 13 of the catheter, which is not shown in these views. In the form shown in FIG. 9, a transparent capillary tube 38 is secured to the hub 39 of the cannula 14a with the passage 40 in the capillary tube in communication with the interior 19a of the cannula and, therefore, arranged for communication with the ports 18 adjacent the tip of the catheter 11, when the latter is in place on the cannula. Handles 31 are attached to the hub 39, just as in the first embodiment.
Accordingly, a drop 41 of liquid placed in the capillary tube 38 will remain substantially stationary as the catheter passes through tissue, but will move in response to a pressure differential within the tube to indicate exposure of the ports 18 either to an increased pressure or to a reduced pressure. For example, a reduced pressure would occur in the epidural space as a result of deflection or tenting of the dura by the blunt tip 13, and this would cause the drop 41 to move inwardly toward the tip of the catheter. The opposite result, an outward movement, will be obtained as the catheter tip enters as cavity filled with fluid, either liquid or gas, under positive pressure.
It will be seen in FIG. 9 that the handles 31 are attached directly to the hub 39 of the cannula 14a, as in the first embodiment. The cannula 14b in the third form 10b, shown in FIG. 10, has a modified hub 42 without any handle, but combined with an adapter 43 forming a releasable extension of the hub and having a tapered fitting 44 as its leading end for seating releasably in a tapered socket 45 in the hub 42. Another tapered socket 47 is formed in the trailing end of the adapter for receiving the tapered end 48 of a syringe, only the barrel 49 of which is shown in FIG. 10. A passage 50 in the adapter connects the socket 47 to the socket 45 to establish communication between the syringe barrel 49 and the bore 51 of the cannula 14b.
In this instance, handles 52 are securely attached to the adapter 43 as the opposite end portions of an elongated plate through which the body of the adapter extends. Accordingly, the handles are detachable from the cannula 14 with the adapter for possible reuse if desired.
In FIG. 11, the same concept has been applied to the placement device to incorporate handles 53 and a capillary tube 54 in an adapter 55 similar to the adapter 43 of FIG. 10. In this case, the capillary tube has a tapered end 57 that is seated, either permanently or detachably, in a tapered socket 58 in the adapter, and the adapter has a tapered fitting 59 that is releasably engaged in a tapered seat 60 in the hub 61 of the cannula 14c. Again, this arrangement permits removal of the adapter, including the handles 53 and the sensing device 54, from the cannula after the latter has served its purpose.
In addition to the frictional coupling accomplished by the tapered parts in the various embodiments, conventional, positive interlocks may be provided on the parts for selective use in the usual manner. In addition, other well-known features may be incorporated, as desired, for special purposes, For example, specially shaped sockets may be provided in the hubs or connectors for connections to special-purpose instruments or fittings, or a so-called Foley catheter-type balloon and inflation tube may be incorporated along the length of the catheter in a well-known manner to aid in retaining the catheter in a cavity. Moreover, the leading end portion of the catheter may be trained or prestressed into a laterally bent shape which it assumes as soon as the cannula is withdrawn, again in a manner that is known. While the catheter has been described as having one or two holes adjacent the tip, it will be apparent that additional holes (not sown) may be spaced along the catheter from the tip to be opened as the cannula is withdrawn, thereby to reduce the change of plugging in use and to increase the flow area where it is desirable to do so. These and other modifications will suggest themselves readily to those skilled in the art as being within the spirit and scope of the invention.
The novel introducer 32 is shown most clearly in FIGS. 12-17, wherein it will be seen that the shank 33 is in the form of an elongated channel, preferably semicircular in transverse cross section, and that the grip 35 is formed by two finger pieces including flaps 62 which extend both above and below the longitudinal axis of the shank, on opposite side thereof, and have two opposed, laterally facing holes or recesses 63 for the gripping thumb and finger of the user. These recesses are centered on the longitudinal axis of the shank 33, and thus align the thrust of the users fingers with the shank to facilitate skin penetration by, and proper direction of, the shank, without significant danger of bending as a result of development of torque during insertion.
Each gripping flap 62 preferably is integrally joined to an upper longitudinal edge 64 of the shank 33, adjacent the end thereof remote from the point 34, by an inner leg 65 extending upwardly from the shank and connected by an outwardly and reversely curving bend 67 to the flap 62, which extends downwardly from the bend to a level well beyond the shank. The inner legs 65 preferably flare or diverge upwardly to facilitate the placing of the catheter 11 into the groove of the shank, and the flaps preferably have slightly concave outer sides formed with somewhat elongated finger recess 63 which are centered vertically on the shank to receive the tips of the thumb and finger of the user, as shown in FIG. 5. This assures the alignment of the thrust with the shank and the point.
This configuration makes it possible to form the introducer 32 inexpensively from a single sheet metal stamping 68 shown in FIG. 16, beginning as a T-shaped blank with a relatively narrow strip 69 for forming the shank, joined at a right angle to the center of a wider strip 70 for the finger pieces. The finger recesses 63 may be depressions that are stamped into theopposite end portions of the wider strip 70 as an incident to the initial stamping operation. As a first shaping operation, the blank may be curved, longitudinally of the narrow strip 69, to form the trough of the shank 33, leaving the opposite end portions of the wide strip 70 in the planes-indicated at 71 in FIG. 13. Then the reverse bends 67 are formed and the concavity is applied to the flaps 62 to complete the introducer except for its point 34.
As shown in FIGS. 12, 14 and 15, the point 34 is defined substantially on the longitudinal centerline of the shank 33 by two arcuate, upwardly facing edges 72 curving concavely downwardly and converging to the point. The edges 72 are substantially arcs of a cylinder that is tangent to the bottom surface of the trough or channel defined by the shank.
Conventional needle-pointing techniques are not practically applicable on a mass production basis to a shank that is open sided and, thus, effectively fiat on one side. Moreover, conventional flat" grinding of the end of a semicylindrical shank on an angle with the longitudinal axis of the shank will produce a generally elliptical cutting edge rather than a point, requiring additional shaping operations to reduce the edge to a point. As shown in FIG. 14, a grinding wheel 73 rotating about an axis 74 and having a rounded edge 75 is passed transversely across the end of the shank 33 while the latter is held generally parallel to the axis 74 of the wheel, and with the centerline of the shank (the bottom of the trough) generally tangent to the arc of the rounded wheel edge 75. Of course, a large number of introducers can be clamped in side-by-side relation to grind points on all the shanks in a single pass. Thus, the novel introducer may be mass produced at low enough cost to be disposable, and yet has a sharp, effective and noncoring point.
It will be evident that the relationship of the radius of curva ture of the rounded edge 75 will determine the sharpness of the point, the ease of penetration, and the length of the point. In addition, the point configuration has the advantage of tending to lift the penetrated wall of a vessel while making a fine, slitlike incision. Although the one-piece construction of the introducer, including the integral grip, is preferred for econo my of manufacture, it will be apparent to those skilled in the art that the grip 35 might be fabricated separately and attached to the shank 33.
From the foregoing, it should be evident that the present invention provides a catheter placement device 10, and cooperating introducer 32, for safe and convenient placement of a catheter 11 in a body cavity 12a without need for a sharp needle of the type that has been used to lead the catheter through the body tissue, with risk of inadvertent puncture of delicate tissue and organs of the body. Instead, the novel and disposable introducer 32 is used simply to open a relatively shallow and fine incision through the tougher outer layers of tissue, and the blunt-end catheter 11 is placed in the body through the incision, leading the stiffer cannula through the tissue andpenetrating beyond the depth of the incision by blunt dissection of tissue.
It has been seen that this is made possible by using a lowfriction resiliently flexible material for the catheter, forming a generally hemispherical, imperforate tip on the catheter, and applying the inserting force immediately behind the tip with a longitudinally stiff, blunt-ended cannula that not only forces the catheter through the tissue into the desired location, but also communicates constantly with at least one laterally opening port near the tip of the catheter. Moreover, the secondary features of the several modified forms add flexibility to the placement device with regard to the manner of attachment of the handle and the different representative sensing devices.
I claim as my invention:
1. A catheter placement device having, in combination:
an elongated resiliently flexible plastic catheter having an imperforate tip at one end shaped for blunt dissection of tissue, a central passage extending through said catheter from the opposite end thereof to said tip, said passage terminating adjacent said tip in a transverse end wall, and at least one laterally opening port adjacent said tip communicating with said passage;
an elongated cannula disposed in said catheter in sliding,
telescoped relation therewith and having a transverse end surface engaging said end wall, the other end portion of said cannula projecting through said opposite end of the catheter;
means on said other cannula end forming a grip for said placement device whereby said imperforate tip is pressed through tissue by a force applied through the cannula against said transverse end wall; and
said cannula having a longitudinal passage opening through the transverse end surface thereof toward said end wall, and said port in said catheter being connected to said cannula passage by means including a connecting passage opening through the central portion of said end wall.
2. A catheter placement device having, in combination:
an elongated catheter having an imperforate rounded tip at one end, a longitudinal passage of preselected diameter extending through said catheter from the end thereof opposite said tip and terminating in a transverse end wall adjacent said tip, and a connecting passage extending from said end wall into said tip, and opening laterally therefrom to form at least one port communicating through said connecting passage with said longitudinal passage;
an elongated cannula having an outside diameter approximately equal to said inside diameter, a longitudinal internal passage, and opposite ends through which the internal passage opens, said cannula being disposed within said catheter with a sliding fit with one of its ends abutting against said wall and with said internal passage communicating with said port through said connecting passage; and
means on the other end of said cannula forming a strip for said placement device whereby said tip is pressed through tissue by a force applied through said cannula and said end wall while said port remains in communication with said cannula passage.
3. A catheter placement device having, in combination:
an elongated resiliently flexible plastic catheter having an imperforate tip at one end shaped for blunt dissection of tissue, a central passage extending through said catheter from the opposite end thereof to said tip, said passage terminating adjacent said tip in a transverse end wall;
an elongated cannula disposed in said catheter in sliding, telescoped relation therewith and having a traverse end surface engaging said end wall, the other end portion of said cannula projecting through said opposite end of the catheter;
means on said other cannula end forming a grip for said placement device whereby said imperforate tip is pressed through tissue by a fore applied through the cannula against said transverse end wall; and
which said tip is generally hemispherical in shape and said cross-passage is offset from the center of curvature toward said tip, said tip being thickened longitudinally of said crosspassage to a nearly rectangular shape to dispose said laterally opening ports in planes extending substantially longitudinally of said catheter.
Citations de brevets