US 3738365 A
An extensible catheter comprising a flexible tubular housing with a circularly cylindrical passage extending therethrough. A flexible metallic helical spring having a plurality of identical turns fits in the passage in abutment with the wall. The innermost boundary of the turns forms an axial guideway for guiding a pair of heads, each disposed on a conduit section which projects beyond the tube. A retainer member makes a fluid-sealing structural fit at each end of the housing, holds the heads in the passage, and makes a sliding fluid-sealing fit with the outer wall of the respective conduit section. The relative axial lengths of the passage and of the heads are such as to permit the axial spacing apart of the heads and therefore the total length of the catheter to be varied.
Description (OCR text may contain errors)
[ 1 3,738,365 June 12, 1973 Primary Examiner-Dalton L. Truluck Att0rney D. Gordon Angus and Donald D. Mon
 ABSTRACT An extensible catheter comprising a flexible tubular housing with a circularly cylindrical passage extending therethrough. A flexible metallic helical spring having a plurality of identical turns fits in the passage in abut- CATHETER Inventor: Rudolf R. Schulte, 600 Pine Avenue,
(loleta, Calif. 93017 Filed: Nov. 1, 1971 Appl. No.: 194,308
Related US. Application Data Continuation-impart of Ser. No. 843,517, July 22, 1969, Pat. No. 3,623,484.
United States Patent Schulte SPRING REINFORCED EXTENSIBLE 10 Claims, 3 Drawing Figures 5 5 .km AA iii-E22: w
ment with the wall. The innermost boundary of the turns forms an axial guideway for guiding a pair of heads, each disposed on a conduit section which projects beyond the tube. A retainer member makes a fluidsealing structural fit at each end of the housing, holds the heads in the passage, and makes a sliding fluidsealing fit with the outer wall of the respective conduit section. The relative axial lengths of the passage and of th w I 0 XVfl R R f v -\\i\\ 0 5 o w c BBm w 5 5 m, a 7 79 %88 3 3 4 /ZZ S 4 21 0 81 n l 01 16R n" m n R u n nu o N m n 5 E u ""43 "Hun" "3 d L n u n u D. u 8A a "l n n A n 82 "up t a i. m C e m m m Rm O r. W: n me B WIT l S t "N" "A e w T a mT wm m N m mmm SGFFRS G u H E C T I owm n n mm& 99999 H mm NHHHHH N/ I. .f. 7294 CGO U .l 1 d E Std R 56124 6 9028 5 UIF .m 62733 9 ll] .1 2 9 2 6 MMH% %6 6 PATENIEWZ 3.738.365
I 45 l I 47 INVENTOR. 41/000 R. 50/0475 5Y2 6 z i A TTO/Q/VfVS.
CROSS REFERENCE TO OTHER PATENT APPLICATION This patent application is a continuation-in-part of applicants co-pending U.S. Pat. application, Ser. No. 843,517, filed July 22, 1969, now U.S. Pat. No. 3,623,484, entitled Physiological Shunt Systems.
This invention relates to catheters for use in drainage of fluids within the human body and in particular to a spring-reinforced catheter whose total length can adjustably be varied.
Adjustably varied catheters are known in the art, one example can be found in applicants parent U.S. Pat. No. 3,623,484 referred to above entitled Physiological Shunt Systems. It is an object of such a catheter to lengthen as its user grows, without requiring movement of its ends (which may be affixed to particular regions of the human body), or requiring stretching'of the device, or requiring its removal and replacement by a catheter of a different and more suitable length.
The aforesaid catheter performs well, but in practice its has been found desirable to isolate the relatively sliding members from external compressive and kinking forces, and also to reduce surface-to-surface contacts of like substances such as silicone rubber which might have a tendency to adhere to each other, and cause galling upon movement, or which might tend to become fixed. Accordingly, it is an object of this invention to provide an extensible catheter which is reinforced to resist external forces and kinking and which can provide for relative movement principally between dissimilar substances thereby reducing the tendency of the device to stick or to gall.
An extensible catheter according to this invention comprises a flexible tubular housing which has an interior wall bounding a passage through the housing. The
passage has a central axis. A flexible metallic helical spring has a plurality of identical turns and a constant inner and outer diameter. The spring extends axially in the passage in abutment with the wall. The innermost boundary of said turns forms a guideway. A conduit section is inserted in each end of the passage and a head on each conduit section projects laterally beyond the sections and makes a sliding engagement with the guideway. There is a flow passage through each of the sections and its respective head.
A pair of retainer members each makes a fluidsealing structural joinder with the housing adjacent to a respective end thereof, and projects away from the housing. It has an inner peripheral surface which surrounds its respective conduit section so as to make a sliding fluid-sealing fit with the other wall of the respective conduit section and retains the head in the passage. The relative axial lengths of the passage and of the heads are such as to permit the axial spacing apart of the heads to be varied. The heads slide in the guideway and make sliding contact only with the said spring.
According to a preferred but optional feature of this invention, the conduit sections, heads and the housing are made of silicone rubber.
According to still another preferred but optional feature of the invention, the spring is indented into the interior wall of the housing.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings in which:
FIG. 1 is a perspective view of a drainage system for hydrocephalus utilizing the present invention;
FIG. 2 is an axial cross-section taken at 22 in FIG. 1; and
FIG. 3 is a cross-section taken at 33 of FIG. 2.
FIG. 1 shows an infant 10 which is afflicted with hydrocephalus, which is an ailment in which cerebrospinal fluid does not drain properly from the head, with consequent compressive pressure on the brain and enlargement pressure inside the skull.
The shunt system 11 is provided to drain away excess fluid, and ordinarily utilizes a catheter 12 such as that shown in the applicants presently co-pending patent application Ser. No. 47,657 filed June 19, 1970, now U.S. Pat. No. 3,626,950, entitled Catheter With Augmented Drainage Means, which is thrust into the region of the brain to be drained and which drains to a combined check valve and pump 13 which may be of the type generally shown in Schulte U.S. Pat. No. 3,111,125 issued Nov. 19, 1963 entitled Drainage Device.
A catheter 14 according to this invention is joined to the outlet of pump 13 and will extend through various veins 15 to the heart 16 into which the fluid is discharged. The catheter includes a pair of conduit sections l7, 18 which are joined together by means yet to be described.
Conduit section 18 will customarily be provided at its end with slit valves 19 of the type generally shown in Heyer U.S. Pat. No. 3,020,913 issued Feb. 13, 1962, entitled Surgical Drain. Protuberances 20 may be formed on the outer wall of conduit section 18 so as to aid in fixing the end at some desired location. The details of the slit valves and protuberances form no part of the present invention.
The foregoing system receives excess fluid at catheter 12, passes it through the check valve and pump 13 catheter 14, and discharges into the heart. It is a feature of the ailment known as hydrocephalus that while it af fects adults it is generally an ailment of children and the children of course will grow in stature. As can be appreciated from FIG. 1, the length between the pump and the tip within the heart will change as the child grows. Until the catheter shown in the aforesaid Shulte U.S. Pat. No. 3,623,484 was invented, it was common practice to remove and replace the catheter from time to time in order to accommodate the child's growth. This of course is an undesirable procedure to repeat any more often than necessary if at all, and it is therefore an object of this invention to avoid this situation by providing means whereby the device can elongate or extend as the child grows. It will also be understood that this device may be located in such a manner that change in length can occur on either or both sides of its central point and that the method or place of installation as shown in FIG. 1 is not limiting in any manner.
Catheter 14 is shown in full detail in FIG. 2. It has a housing 25 with an interior wall 26 which forms a tubular passage 27 extending from end to end of the housing. Within the housing there is disposed a flexible metallic helical spring 30 which has an inner diameter 31 and an outer diameter 32. The spring has a plurality of turns 33, 34 which are equally spaced apart by spacing 35 (sometimes called the pitch of a spring). The inner and outer diameters of all the turns are equal and are defined by the outermost boundaries, of the spring wire. The spring at its outermost diameter bears in abutment against wall 26 of the passage. ln manufacturing the device, the tube may be softened with xylene and the spring inserted. Then as the xylene evaporates, the tube shrinks upon the spring so as to indent the spring into the wall forming a wavy pattern in the wall of the tube. However, waves such as wave 36 will not extend inwardly beyond the inner diameter for reasons yet to be described. The spring terminates short of both of the ends of the housing.
The conduit sections 17, 18 have respective heads 40, 41 on their ends inside the passage, the outer diameter of the heads is substantially equal to the inner diameter of the spring and the axial spacing 35 is smaller than the axial length 42 of the heads. The heads project laterally beyond the outer wall of the respective conduit section. Accordingly the turns, or rather the innermost boundary of the turns, comprise a guideway for the heads, and the relative dimensions are such that the heads cannot become trapped between the coils of adjacent turns.
Retainer members 45, 46 are closely fitted into the respective ends of the passage in abutment with the ends of the spring. The retainer members may be cemented or otherwise joined to the housing to make a continuous peripheral fluid-sealing joint such as joint 47 and 48.
Each retainer member has an inner peripheral surface 49, 50 respectively which surrounds its respective conduit section and makes at two places a sliding fluidsealing fit 51, S2, S3, 54. There is thereby formed a substantially fluid tight arrangement. It will be noted that when the heads move axially in the housing, fluid can bypass them through the spacing between adjacent turns so that there is no pressure developed in the fluid as while the heads are being moved which might cause leakage of the device.
Formation of the retainer member as shown provides grooves 55, 56 to which sutures may be tied for fixation of the housing if desired.
The heads, conduit sections, and housing will be made of medical grade silicone rubber. This material is flexible and permits substantial relatively easy bending and compression which will be resisted by the flexible spring. The spring may be made from round stainless steel wire of approximately 0.010 inches diameter wound with an outer diameter of approximately 0.110 0.l 15 inches with a pitch spacing of approximately l/32 inches.
The indentation of the spring turns into the wall of the housing will not be sufficient to cause the material of the wall of the housing to abut against the head. Therefore there is provided a closely-sized guideway for the heads in which there is no sliding surface-tosurface contact between the heads and another silicone rubber surface which might tend to seize or to gall. Instead contact is between the rubber head and the metal of which the spring is made. This causes only a light drag, and is not subject to adherence or galling. The spring protects the head from binding compressive forces.
The relatively smaller line contact between the conduit sections and the retainer members at the sealing fits 51-54 do not cause much drag, and do form a sliding fluid-seal. Furthermore, the retainer members are preferably made of a different material from that of the housing, one which will be inherently stiffer, such as cast nylon in order that it cannot be compressed against the wall of the conduit section so as possibly to occlude or drag on it. Also, it is a different material than that of the conduit segment so there is no tendency to adhere or to gall. The retainer members can conveniently be made of relatively stiff nylon so as to make a light interference fit on the order of perhaps a few thousands of an inch with the wall of the tubing. The stiff retainer member will provide good support for sutures which may be tightly tied to the respective grooves.
There is provided by this invention an extensible catheter for drainage of fluids from the human body such as hydrocephalus fluids in which ease of sliding of the telescoping members is provided, in which surfaceto-surface contact of materials which may tend to adhere to one another or to gall one another, is eliminated, and in which the possible effect of external forces in limiting relative internal movement is reduced if not entirely eliminated.
This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of illustration and not of limitation but only in accordance with the scope of the appended claims.
I. An extensible catheter for use in a physiological fluid shunt system, said catheter comprising: a flexible tubular housing; an interior wall bounding a passage through the housing, the passage having a central axis; a flexible metallic helical spring having a plurality of identical turns and a constant inner and outer diameter, the said spring extending axially in the passage in abutment with said wall, the innermost boundary of said turns forming a guideway; a pair of conduit sections slidably mounted in apposition with one another within said passage, a head on each conduit section laterally projecting beyond the sections and making a sliding engagement with the said guideway, there being a flow passage through each sections and its head; and a pair of retainer members each making a fluid-sealing structural joinder with the housing adjacent to a respective end thereof, and projecting away from said housing, and having an inner peripheral surface which surrounds its respective conduit section so as to make a sliding, fluid-sealing fit with the outer wall of the respective conduit section and to retain the head in the passage, the relative axial lengths of the passage and ofthe heads being such as to permit the axial spacing apart of the heads to be varied, the heads sliding in the guideway and making sliding contact only with the said spring.
2. A catheter according to claim 1 in which the spring is indented into the interior wall of the housing.
3. A catheter according to claim 1 in which the conduit sections, heads and the housing are made of silicone rubber.
4. A catheter according toclaim 3 in which the spring is indented into the interior wall of the housing.
5. A catheter according to claim 3 in which the retainer members are made of nylon, and are stiffer than the housing. I
6. A catheter according to claim 5 in which the spring is indented into the interior wall of the housing.
7. A catheter according to claim 1 in which the axial length of the heads is greater than the axial spacing of the turns of the spring whereby the heads cannot be trapped between adjacent turns.
10. A catheter according to claim 9 in which the retainer members are made of nylon, and are stiffer than the housing.