Catheter shield and test structure

Equipment is disclosed for shielding a catheter such as a balloon-tipped vascular catheter from contamination during testing and insertion and for shielding a substantial reserve catheter section for use if catheter re-positioning is necessary. As shown, the structure includes two interconnecting envelopes which physically isolate the catheter. One envelope is designed to shield the distal end portion of the catheter during testing for luman patency and balloon inflation. The other envelope is extendible to cover the entire length of catheter intended for insertion into the patent upon completion of required tests. The second envelope thereafter provides a means for advancement or re-positioning of the catheter or withdrawal of the same without physical contact by the hands or exposure to airborne contaminants.

FIELD OF THE INVENTION 
This invention relates to catheters such as intravascular catheters and 
more particularly to equipment for maintaining the sterility of such 
catheters by physically isolating all portions of a catheter intended for 
insertion into a patient's blood vessel or other body cavity from the time 
the seal or the container in which the catheter is stored is broken, 
during testing and insertion and during subsequent use. 
BACKGROUND OF THE INVENTION AND THE PRIOR ART 
The development of apparatus and techniques for maintaining the sterility 
of catheters, such as thermodilution flow-directed balloon catheters used 
for measuring cardiac output and for obtaining other diagnostic data, has 
received critical attention as the use of such products has expanded. The 
packaging of the catheter in gas-sterilizable containers and in single-use 
kits having all of the items needed for insertion of the catheter and for 
use in carrying out the required procedure and by rigorously following 
sterile procedures have all contributed to a substantially reduced risk of 
contamination and infection. However, even when following the most 
rigorous procedures contamination may occur, particularly when the patient 
is being treated under emergency conditions. At best, a potentially 
contaminated catheter may have to be discarded prior to use when sterile 
procedures have not been followed. 
A form of sterility sleeve used to maintain a portion of an indwelling 
catheter free from contamination for later use when it becomes necessary 
to re-position the catheter is disclosed in U.S. Pat. No. 4,327,723 to 
Paul L. Frankhouser. This sleeve is extended over a length of catheter 
immediately adjacent to the portion inserted into the vascular system of 
the patient, thereby physically isolating a reserve section of catheter 
from the atmosphere for use should it later become necessary to reposition 
the catheter. 
U.S. Pat. No. 4,568,334 to Lawrence Lynn discloses a means for more 
comprehensive treatment of the contamination problem. In the Lynn patent, 
a combined storage, dispensing and preparation container is provided for 
an intravascular balloon catheter. The container includes a plurality of 
interconnected compartments in which different parts of the catheter are 
housed. Lynn's compartments include a test chamber for testing the 
integrity of the catheter balloon, an adjacent section in which a pleated 
sleeve is housed in what is termed a "trough compartment," a main 
compartment in which a substantial section of catheter may be stored and a 
connector compartment in which the proximal end of the catheter is 
located. The distal tip of the catheter is withdrawn from the test chamber 
once balloon integrity is tested, until the tip is located within the 
pleated sleeve by a pumping action of the sleeve. The pleated sleeve is 
then attached to a catheter introducer in place within the patient's blood 
vessel and the catheter is then advanced into the vessel by a reverse 
pumping action of the sleeve. 
U.S. Pat. No. 4,622,033 to Taniguchi discloses a packaging construction for 
a urinary catheter comprising a lubricant reservoir and a tubular envelope 
or shield. A balloon-tipped urinary catheter is advanced into the 
lubricant reservoir prior to use. The lubricant reservoir has a frangible 
seal so that the reservoir can be removed once the catheter has been 
lubricated. 
U.S. Pat. No. 4,637,404 to Gessman discloses a dispensing container for a 
cardiac pacing electrode in which a flexible sheath or sleeve comprising 
an accordion section 32 and another gathered or accordion section 34 is 
provided for advancing the electrode by grasping the wire through the 
sleeve. 
OBJECTS AND ADVANTAGES OF THE INVENTION 
The primary object of the present invention is the protection of a vascular 
catheter from contamination during testing and insertion of the catheter 
in a manner which maintains a substantial portion of the catheter not 
indwelling in the patient in physical isolation from the atmosphere for 
subsequent use as may be later required. A related object is the provision 
of a simple and effective means for testing, insertion and re-positioning 
of a vascular catheter in a way which always isolates the catheter from 
the hands of attending personnel as well as from airborne contaminants. 
A still further object of the invention is the provision of simple and 
relatively inexpensive components for accomplishing the objectives just 
above mentioned. 
A still further object of the invention is the provision of equipment for 
straightforward and trouble-free testing and insertion of a balloon-tipped 
vascular catheter which lends itself to unassisted use by a single 
attendant. 
A still further object of the invention is the reduction in the number of 
catheters which must be discarded due to accidental contamination during 
testing and insertion of a vascular catheter. 
Other objects and advantages of the invention will become apparent upon 
reference to the following detailed description of a preferred embodiment 
of the invention.

DETAILED DESCRIPTION OF THE INVENTION 
Although the catheter illustrated in FIGS. 1-6 is a conventional four-lumen 
thermodilution catheter, other types of catheter may be advantageously 
provided with the sheath and test chamber construction of the present 
invention. Briefly stated, and by way of background, the catheter 
illustrated comprises an elongated flexible tubular body member 10 which 
typically has four passageways or lumens extending lengthwise therein. 
Body member 10 preferably has a pre-curved region adjacent the tip which 
is provided as an assistance to proper catheter placement as will be 
understood by those skilled in the art. Separately formed tubes or lumens 
11-14 are respectively joined to the lumens of the catheter body member at 
the proximal end thereof within a molded fitting 15. Typically the tubes 
11-14 are independently heat fused or adhesively joined to the lumens 
integrally formed within the body member so that four independent, 
non-communicating passages are formed. The proximal ends of the tubes 11, 
12 and 14 are provided with Luer adapters or fittings 16-18 for connection 
to fluid devices. Fitting 18 is provided with a shut-off valve 19 for 
purposes to be explained hereinafter. The lumens joined to tubes 11 and 12 
extend respectively to a port 20 at the catheter's distal tip and to a 
port 21 which is spaced approximately 30 centimeters from the distal tip. 
These lumens provide unimpeded flow passages for injecting fluids into the 
blood stream or for taking pressure measurements in a manner known in the 
art. The lumen joined to tube 13 houses leads for a thermistor 22 disposed 
within a port located within the pre-curved region on the inner side of 
the radius about 4 centimeters from the catheter's distal tip. The 
thermistor measures a change in temperature of a fluid ejected into the 
bloodstream through port 21 to provide a measurement of cardiac output as 
is well understood by those skilled in the art. For temperature 
measurement, the proximal end of tube 13 is equipped with an adapter 23 
which houses an electrical connector for connecting the thermistor to 
suitable temperature-monitoring equipment. Finally, the lumen joined to 
tube 14 leads to the inflatable balloon 25 located just adjacent to the 
distal tip of the catheter. This lumen provides an uninterrupted flow 
passage for injecting an inflation media applied through adapter fitting 
18 for inflation of the balloon 25. Valve 19 provides a means for closing 
this lumen once the balloon is properly inflated and allows for its 
deflation, as required. The catheter is also provided with suitable 
markings 26 at 10-centimeter intervals which give an indication to the 
user of the length of the catheter which has been inserted into the 
patient's blood vessel. 
In carrying out the invention, there are two interconnected tubular 
envelopes provided for physically isolating all portions of the catheter 
that are liable to be inserted into the vascular system of the patient. 
The catheter is physically isolated from the atmosphere during testing of 
the balloon and flushing of fluid through the lumens by both envelopes. 
After testing, the distal end of the catheter is physically retracted into 
one of the envelopes and the other is discarded. During insertion, all 
portions not within the vascular system are protected by the remaining 
envelope. Still further, a substantial length of catheter is isolated for 
use during the time the catheter remains within the patient's vascular 
system. This reserve section is thus available in physical isolation 
within one of the envelopes without risk of contamination by the patient 
or attendants so that it may be used when repositioning the catheter as 
may be required. In its preferred form, the first envelope comprises an 
elongated flexible transparent tubular sheath 30 formed of a sheet-like 
impervious material which readily yields to finger pressure. The sheath 
surrounds the catheter and extends from a point adjacent the proximal end 
where it is secured to the catheter preferably via coupling means 31 
comprising a hub 32 having a bore through which the catheter is passed. 
The hub is secured to the catheter by adhesive or other suitable means in 
a manner providing a substantially impervious seal. Hub 32 tightly 
interfits with a cylindrical coupling element 33. The parts are preferably 
locked in place by means of a slot 33a which receives a locking pin 32a 
projecting from hub 32. The proximal end of sleeve 30 fits over and is 
tightly secured to coupling element 33 by any suitable means such as 
elastic "O" ring 34 or by shrink fitting the sleeve directly onto the 
coupling element. 
The distal end of sleeve 30 is secured to a second coupling means 
comprising coupling element 35 which has a throughbore 36 as shown in FIG. 
3 which is sized to allow free passage for the catheter 10. Sealing means 
such as used in holding the proximal end of the sleeve on coupling element 
33 affixed to the distal end of the sleeve to coupling 35. FIGS. 1-4 and 6 
show an elastic "O" ring 37 for this purpose. 
As can be seen in the drawings, particularly FIGS. 1, 4 and 6, the sleeve 
30 is of large enough diameter relative to the catheter and is readily 
collapsible so that a substantial amount of relative axial movement can be 
achieved easily with the excess sleeve material being gathered or bunched 
up upon the catheter upon movement of the sleeve ends towards one another 
and being readily ungathered as the sleeve ends are separated. In overall 
length, the sleeve is capable of extension from a fixed point at 31 to the 
distal tip of the catheter. 
Preferably a section of relatively flexible, somewhat resilient, plastic 
tubing 39 formed of polyurethane or the like extends rearwardly from the 
fitting 35 within sleeve 30. The tubing 39 is formed co-axially of the 
throughbore 36 and is dimensioned so that the catheter passes freely. The 
tubing 39 should have sufficient flexibility and resilience so that the 
application of a moderate amount of finger pressure exerted through sleeve 
30 onto the outside walls of the tubing will compress the walls against 
the catheter, holding it in position against relative movement for reasons 
which will appear hereinafter. 
The second envelope comprises a test chamber within which the distal 
portion of the catheter is to be positioned so that certain required 
tests, such as balloon inflation testing and catheter lumen patency, can 
be carried out and viewed in physical isolation from the environment 
immediately prior to use of the catheter. With reference to FIG. 1 which 
illustrates the position in which the catheter appears when the lid stock 
of the package in which it is stored in sterile condition is removed, the 
test chamber of the preferred embodiment of the invention comprises an 
elongated tube 40, preferably formed of transparent material so that the 
distal end of the catheter is exposed to view. When used with a catheter 
having a balloon at its distal tip, tube 40 has an enlarged end which may 
take the form of a separate cup or receptacle section 41 joined thereto, 
which is also preferably formed with a transparent wall section as shown 
in FIG. 1, which illustrates the position in which the catheter is ready 
to be tested. In this condition it is noted that the distal catheter tip 
with balloon 25 in the uninflated condition is preferably already within 
the cup 41 and the ejectate lumen 21 is within the tube 40. As is shown in 
FIGS. 2 and 3, the interior of the cup section 41 is large enough to 
provide ample clearance when the balloon is fully inflated. A vent is 
conveniently located in lid 42 as seen at 42a in FIG. 2, although a vent 
opening may be provided in other locations and in some instances may be 
unnecessary. Tube 40 may be a rigid tube with a pre-formed bend to 
accommodate the pre-formed bend common to pulmonary artery catheters, in 
its preferred form a flexible transparent tubing formed of polyurethane or 
the like is utilized. The flexible tubing is packaged with its end curved 
to the curvature of the distal end of the catheter having the pre-formed 
bend and it has been found that such tubing will take a nice set when 
sterilized after being positioned in the package with the required 
curvature. In FIG. 3, the curvature is not to scale and is somewhat 
exaggerated, it being shown for illustrative purposes only. 
In order to releasibly interconnect the two envelopes, the proximal end of 
tube 40 carries a coupling hub member 43 which is of cylindrical shape so 
as to tightly fit into the cylindrical cavity 44 of coupling member 35 as 
may be best seen in FIGS. 2 and 3. Preferably a resilient sealing ring 45 
fits within a recess 46 in the outer cylindrical wall of coupling member 
43. Sealing ring 45 presses against the inner wall surface of the 
cylindrical cavity 44, providing a substantially air-impervious seal. The 
members are preferably locked together by releasible locking means which 
preferably comprises an L-shaped bayonet slot 47 on one member which 
receives pin 48. 
As can best be seen in FIG. 1, the combined length of the envelope 
comprised of tube 40 and cup 41 is sufficient to extend proximally of 
catheter ejectate port 21 when the catheter is positioned with its distal 
tip within cup 41. As seen in FIGS. 2 and 3, tube 40 has a large enough 
internal diameter relative to catheter 10 to allow for free flow of liquid 
downwardly into cup 41 when the cup is held below the level of the 
ejectate port. 
As indicated above, the catheter is packaged with the two envelopes 
interconnected by the coupling parts 35 and 43 so that a section of 
catheter (hereinafter sometimes called the "insertion zone"), comprising 
the entire length of the catheter running from the distal tip that is 
liable to be inserted into the patient's vascular system, is physically 
isolated from the ambient. When the lid stock is removed from the 
container tray (not shown) within which the catheter and other items 
needed for its use are housed, all portions, except for that portion 
proximal of the fitting 31, are thus in physical isolation. The user 
removes the assembly comprising the catheter housed within its protective 
envelopes from the tray and commences the test procedure, positioning the 
test chamber envelope below the level of the remainder of the catheter. By 
injecting saline solution through the fitting 16, one can visually observe 
the flow of solution which flows down tube 40 from ejectate port 21, thus 
simultaneously flushing the lumen 11 and verifying that it is 
unobstructed. During this phase of the test procedure, the tube 10 and the 
receptacle 41 are allowed to incline downwardly so that saline solution 
flowing out through port 21 freely flows towards receptacle 41. The user 
next injects saline solution through Luer fitting 17 and tubular lumen 12 
thus flushing this lumen and filling the receptacle with saline solution. 
The balloon is then inflated by injecting a charge of inflation medium 
through Luer fitting 18. The balloon can be visually observed through the 
clear walls of cup 41. Symmetry of the balloon can be seen and leaks 
detected through the presence of bubbles flowing upwardly through the 
clear saline solution. If no leaks are detected and the balloon is seen to 
be appropriately symmetrical, the balloon is thereupon deflated. The 
distal end of the catheter is now ready to be extracted from the envelope 
comprising the test chamber. 
To retract the catheter from the test chamber comprising tube 40 and cup 
41, the front hub 35 is held by one hand and the rear hub by the other and 
the bunched material of sleeve 30 extended by physically separating the 
hubs. Since the sheath is as long as the catheter, the distal catheter tip 
is now within the hub 35. As the catheter is withdrawn from the test 
chamber, a resilient wiper 44a shown in FIG. 3 squeegees saline solution 
from the catheter back into the test chamber. 
The test chamber is then removed by disconnecting coupling member 43 from 
coupling member 35 and discarded. The catheter is now ready for insertion 
into the vascular system of the patient. 
Although the catheter may be inserted into a blood vessel by use of other 
techniques, it is preferably introduced using a standard sheath introducer 
50 of known construction (FIGS. 4 and 6). As is known in the art, 
introducer 50 comprises a hollow valve body 51, and a thin walled sheath 
52 which is adapted to be inserted into a blood vessel as schematically 
shown in FIGS. 4 and 6. The introducer assembly also includes a soft 
rubber hemostasis valve 53, located within hollow valve body 51 to inhibit 
back-bleeding. The valve is provided with a narrow slit, not shown, which 
is biased to close when catheter 10 is not in place and yields to form a 
seal around the catheter when the latter is introduced. Body 51 is further 
provided with a side port 54 which communicates with the interior of 
sheath 52 for fluid replacement and blood sampling if necessary prior to 
and during placement of the catheter. 
The front connector element 35 is sized to interfit with a male connector 
55 formed integrally with valve body 51. The connector parts are 
configured to provide a seal against air or airborne contaminants. 
FIG. 4 illustrates the catheter with its distal tip advanced to a point 
just beyond the distal end of sheath 52. In order to advance the catheter, 
it is grasped through the sheath between the thumb and forefinger of one 
hand at a point five to ten centimeters behind hub 35 and gently pushed 
forwardly so that the distal tip passes through the introducer into the 
blood vessel. At the end of each forward stroke by the one hand the grip 
on the catheter is relaxed and the thumb and forefinger of the other hand 
apply pressure through tube 39 to hold the catheter in place while the 
gathered material of sheath 30 is moved away from the hub 35 in a reverse 
stroking motion. A series of forward and reverse strokes, while holding 
the catheter against movement on each reverse stroke, effect advancement 
of the catheter to the wedge position. If re-positioning becomes 
necessary, a reserve section of catheter extended from front hub 35 to 
rear hub 32 is always maintained in contamination-free condition. 
The catheter may be partially withdrawn during re-positioning with the same 
series of forward and reverse strokes with the exception that the catheter 
is grasped with the thumb and forefinger of the stroking hand on the 
reverse stroke and held against movement by pressure exerted through 
tubing 39 by the thumb and forefinger of the other hand on the forward 
stroke. To effect complete withdrawal proximal hub 31 may be grasped and 
gently pulled backwardly until the catheter is fully retracted into sheath 
30 or the distal hub 35 may be disconnected from the introducer and the 
catheter directly grasped and withdrawn. 
Through use of the two envelopes, it can be seen that all portions of the 
catheter which may be introduced into the vascular system can be protected 
from external contamination from the time of sterilization until the 
catheter is withdrawn from the patient. During testing the balloon and all 
fluid flow ports on the body of the catheter are within the envelope 
comprising the test chamber and can be readily inspected and tested prior 
to catheter use. Saline solution flushed through ports 20 and 21 is 
confined to the test chamber. Following testing and immediately prior to 
use, all portions of the catheter are within the other envelope. In 
emergency conditions, the catheter can be tested and manipulated even 
without protective gloves should that be necessary.