U.S. patent number 3,893,448 [Application Number 05/419,109] was granted by the patent office on 1975-07-08 for catheter device for use in detecting gas in body fluids and tissue.
Invention is credited to John W. Brantigan.
United States Patent |
3,893,448 |
Brantigan |
July 8, 1975 |
Catheter device for use in detecting gas in body fluids and
tissue
Abstract
A blood or tissue gas diffusion catheter device comprising a
catheter having a lumen therethrough and provided with a solid
distal end portion enclosed within a membrane permeable to gases
that might be found in blood or tissue, said distal end portion
being shaped to provide a helical path over the outside thereof
communicating with the lumen of the catheter, and said end portion
being shaped to permit direct insertion of the distal end portion
into the body of a patient without the use of a cannulated needle
or an otherwise preformed entry.
Inventors: |
Brantigan; John W. (Salt Lake
City, UT) |
Family
ID: |
23660823 |
Appl.
No.: |
05/419,109 |
Filed: |
November 26, 1973 |
Current U.S.
Class: |
600/364 |
Current CPC
Class: |
A61M
25/0069 (20130101); A61B 5/145 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); A61M 25/00 (20060101); A61b
005/00 () |
Field of
Search: |
;128/2E,2G,2L,2.1E,2.5R,348,214 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Howell; Kyle L.
Attorney, Agent or Firm: Hill, Gross, Simpson, Van Santen,
Steadman, Chiara & Simpson
Claims
I claim:
1. A catheter device for use with analyzing apparatus to obtain
samples of gases from the blood or tissue of a patient, said device
including a cannula carrying a distal end portion covered by a
tubular membrane permeable to body gases and insertable into a
blood vessel or tissue of a patient, wherein the improvement
comprises:
said distal end portion being solid throughout its length, and
said solid end portion being shaped to provide a path for gases
between its external surface and said membrane covering it leading
to the lumen of said cannula.
2. The catheter device in claim 1, wherein
said solid end portion is grooved externally to provide the path
for gases.
3. The catheter device of claim 1, wherein
said solid end portion is provided with a helical groove in its
external surface to provide the path for gases.
4. The catheter device of claim 1, wherein
said solid end portion contains a plurality of helical grooves in
its external surface to provide the path for gases.
5. The catheter device of claim 1, wherein
said distal end portion comprises a solid bar of material polygonal
in cross section and of less size than the inside diameter of said
tubular membrane,
said bar being twisted to contact said membrane at spaced
intervals.
6. The catheter of claim 1, wherein
said solid distal end portion terminates in an end of sufficient
size to close the end of said tubular membrane, and which end
slopes at its distal face to provide a sharp point, whereby
said catheter device may itself be positioned in the body of a
patient without aid from other entry establishing means.
7. The catheter device of claim 1, wherein
said distal end portion has a solid portion extending throughout
the length of the distal end portion of an area in the range of
0.54 to 0.833 of the cross sectional area of the inside of said
tubular membrane.
8. The catheter device of claim 1, which has an overall outside
diameter less than 0.035 inch.
9. The catheter device of claim 5, including
an end member attached to said solid twisted bar of a size to close
the end of said tubular membrane and having a sloping distal face
terminating in a sharp point.
10. The catheter device of claim 6, including
a monofilament covering the sloping face of said end but made of
sufficiently thin and strong material as not to interfere with the
insertion of the device into the body of a patient.
Description
BRIEF SUMMARY OF THE INVENTION
Heretofore, catheter devices were constructed in which the catheter
was a complete cannula up to a closed distal end and the distal
portion of the catheter was covered by a membrane permeable to
gases in body fluids such as blood, or extracellular fluid of
tissue. These catheters were used to acquire samples of the gas
which passed through the membrane and then through the lumen of the
catheter. In most instances, holes were drilled, or otherwise
provided through the wall of the catheter leading into the lumen
thereof through which the gas passed into the lumen of the
catheter. Catheter devices so constructed were severely limited in
minimum overall diameter by virtue of the lumen in the catheter,
required extreme difficulty in providing small apertures through
the wall of the catheter leading into the lumen, and there was
consequent weakening of the cannular tubing by virtue of those
apertures. Such catheters were also objectionably expensive to
manufacture.
Minimum trauma to the blood vessel or tissue in which the distal
end portion of the catheter device is inserted is highly desirable.
With that in mind, an optimum catheter device is one that provides
a sufficient membrane diffusion area with a minimum overall
diameter. By way of the instant invention, applicant has reduced
that overall diameter to a minimum not heretofore reached. Also, in
the instant invention the provision of apertures through the wall
of the cannula has been eliminated along with its difficulty and
expense, and the distal end portion of the catheter has not been
weakened to an objectionable extent. Furthermore, the instant
invention is so constructed that it may be directly inserted in a
patient's body without the aid of a preferred entry or the use of a
cannulated needle.
The instant invention comprises a catheter device including an
elongated catheter or cannular having a lumen therethrough with a
solid distal end portion integral with the catheter or attached to
the end thereof in a known manner. The solid end portion, and
preferably the catheter itself, are entirely covered with a
membrane of a material permeable to body gases such as oxygen,
carbon dioxide, nitrogen, argon, helium, anesthetic agents, inter
alia. The solid end portion terminates on the slant so that the
lower part thereof is the equivalent of a pointed end which,
notwithstanding being covered by the membrane. may be directly
inserted into the body of the patient. The solid end portion is
also formed to provide a helical path leading to the lumen of the
catheter between the outside surface of the end portion and the
membrane. Preferably, this is accomplished by providing a single or
double helical groove in the solid end portion. In effect, the
lumen of the cannula heretofore used, has been transferred to the
outside of the solid end portion. This provides a smaller overall
diameter of the device than was heretofore obtainable, and also
provides ample diffusion area for the gas passing through the
membrane when the opposite end of the catheter is connected to the
vacuum system of a mass spectrometer or other analyzing device.
There is one other way of providing the instant invention by way of
connecting a rectangular piece of material to the end of the
catheter and then twisting that rectangular piece of material to
form the helical path. This method requires the attachment of a
sloping end to the twisted rectangular member so that the device
may be placed in the body of a patient directly and without the use
of a needle or a preformed entry.
Other objects, features and advantages of the invention will be
readily apparent from the following description of certain
preferred embodiments thereof, taken in conjunction with the
accompanying drawing, although variations and modifications may be
effected without departing from the spirit and scope of the novel
concepts of the disclosure.
BRIEF DESCRIPTION OF THE DRAWING
All figures in the drawing are extremely enlarged for purposes of
clarity in illustration.
FIG. 1 is a fragmentary vertical sectional view, with parts shown
in elevation, of a catheter device having a solid distal end
portion with a helical groove therein;
FIG. 2 is a vertical sectional view taken substantially as
indicated by the line II--II of FIG. 1, looking in the direction of
the arrows;
FIG. 3 is a fragmentary sectional view of the structure of FIG. 1
showing the same from a different angle;
FIG. 4 is a view similar in character to FIG. 1, but illustrating
the solid distal end portion on the catheter device as having a
double helical groove in the surface thereof;
FIG. 5 is a vertical sectional view taken substantially as
indicated by the line V--V of FIG. 4;
FIG. 6 is a view similar in character to FIG. 3, but showing the
connection of the double helical groove with the lumen of the
catheter;
FIG. 7 is a view similar in character to FIGS. 1 and 4, but
illustrating the solid portion at the distal end of the catheter as
being a rectangular piece of material twisted to provide the
helical path for gas;
FIG. 8 is a vertical sectional view taken substantially as
indicated by the line VIII--VIII of FIG. 7; and
FIG. 9 is a fragmentary sectional view illustrating the connection
of the helical path with the lumen in the catheter or cannula.
DETAIL DESCRIPTION OF THE SEVERAL EMBODIMENTS
In the first embodiment of the invention, illustrated in FIGS. 1, 2
and 3, there is shown a catheter device including a catheter in the
form of a cannula 1 having a lumen 2 extending therethrough. The
cannula 1 carries a solid distal end portion 3 having no lumen.
Both the cannula 1 and end portion 3 are preferably made of
stainless steel, but a suitable plastic material might also be
utilized, if desired. Stainless steel is preferred because of its
strength, the diameter of both the cannula 1 and solid end portion
3 are the same and quite small.
Over both the solid end portion 3 and the cannula 1 is a tubular
membrane 4 which may well be of polytetrafluoroethylene, silicone
rubber, a silicone polymer substance, or equivalent material that
is permeable to gases found in the body and which are to be sampled
and analyzed. The solid end portion 3 is provided with a helical
groove 5 forming a helical path between the outer surface of the
groove and the membrane 4 leading to the lumen 2 in the cannula 1,
and the cannula 1 is beveled at a point 6 in order to establish
good communication between the helical groove and the lumen. It
should also be noted that the groove 5 starts rearwardly of the
distal end of the portion 3 which distal end remains fully solid as
shown at 7 to entirely fill the end of the membrane 4 and is cut
off on the slant to provide a lower sharp point 8. The monofilament
9 of the same material as the membrane 4 may be placed over the end
7 of the portion 3 to prevent contact of the stainless steel or
other material forming the portion 3 with the blood or tissue of
the patient, and the membrane 4 extends a material distance or
fully over the surface of the cannula 1 for the same reason. The
monofilament 9 is so thin and sufficiently strong as not to
interfere with the direct insertion of the distal end portion of
the catheter into the body of the patient without the aid of a
cannulated needle or any other preformed entry. The groove 5 as
represented in FIG. 2 may be shaped in the form a 60.degree. to
approximately 90.degree. angle and of a depth equal to or less than
the radius of the solid portion 3. The angle between the sides of
the groove is not critical but 60.degree. to 90.degree. appears a
satisfactory angle. The entire length of the catheter device
including the cannula 1 and end portion 3 is rather arbitrary, and
depends upon how far the attending surgeon wishes to insert the
device into the blood vessel or tissue of a patient. The end
portion 3 may be attached to the distal end of the cannula 1 in a
known manner, held in position by the structural integrity of the
tubular membrane 4, or in certain instances might possibly be
formed integral with the cannula.
In use, the catheter device is entered into the body of a patient
to a desired location, and gases contained in the body permeate
through the membrane 4 and enter the helical groove 5 which
provides ample diffusion area. The gas then travels along the
groove 5 into the lumen of the cannula 1 which is connected to a
mass spectrometer or other analyzing device. Usually the analyzing
device has a source of suction to assist the flow of gas to the
device.
As stated above, an optimum catheter device is one that provides a
sufficient membrane diffusion area for gases with a minimum overall
diameter. With a small diameter catheter device that may be placed
in the body of a patient without the use of something else to
establish an entry point some structural strength is required. By
providing a cannula with a solid distal end portion and giving that
end portion a configuration so as to establish a path of travel for
the gas between the outer surface of the end portion and the
diffusion membrane surrounding it results in sufficient structural
strength and a desirable small diameter. The sufficient strength is
obtained by eliminating a lumen through the solid end portion and
boring holes or providing slots leading from the outside of the end
portion to the lumen, as was heretofore done. For example, if the
distance between the sides of the groove 5, as seen in FIG. 2, is
60.degree. it would be a solid cross sectional area of 5/6
.pi.R.sup.2 throughout the length of the end portion 3. If the
distance between the sides of the groove 5 at the circumference of
the element 3 was 90.degree., it would be 3/4 .pi. r.sup.2 of solid
material throughout the end portion. Either of these amounts is far
greater than can be obtained by an end portion of the same diameter
with a lumen therethrough and apertures or slots leading to that
lumen. The membrane tube 4 and monofilament 9 can be reduced to
approximately 0.002 inch and the overall outside diameter of the
entire catheter device may be reduced to approximately 0.020 inch,
considerably less than any gas sampling catheter device made
heretofore, insofar as I am aware. While the showing in the
drawings may not be to the proper scale, the above stated figures
are possible.
Should more diffusion area be desired, it is a simple expedient to
provide the same without objectionably sacrificing a portion of the
structural strength throughout the distal end portion 3, as shown
in FIGS. 4, 5 and 6. This is accomplished by double helical
grooving of the end portion 3. In this instance, the structure is
the same as that above described in connection with FIGS. 1, 2 and
3, with the exception that the cannula 1 is provided with an
additional inward bevel 10 directly opposite the bevel 6; and the
solid end portion 3 is provided with a pair of helical grooves 11
and 12 one communicating with the lumen 2 of the cannula 1 at the
bevel portion 6 and the other on the opposite side at the bevel
portion 10. If the space between the grooves 11 and 12, in each
case, is 60.degree. at the outer circumference of the cannula 1,
then the solid area remaining entirely through the end portion 3 up
to the solid end 7 thereof is 2/3 .pi. R.sup.2 in cross sectional
area, and that is more than has heretofore been obtained by way of
a cannulated end portion with slots or holes drilled through the
wall of the cannula. There need be no sacrifice in smallness of
diameter. The device of FIGS. 4-6 functions the same as above
described in connection with FIGS. 1-3 with the exception that
there is more room to accommodate gas diffusing through the
membrane 4.
A structure highly economical to manufacture, and embodying the
instant invention, is shown in FIGS. 7, 8 and 9. Here the membrane
4, monofilament 9, and cannula 1 are the same as illustrated in
FIGS. 4-6. The only difference is the provision of a solid distal
end portion 13 which is simply a strip or rod of material
rectangular in cross-section and twisted as seen clearly in FIG. 7
to provide a helical path for gas or gases diffusing through the
membrane 4. In this instance, it is necessary to attach a closed
end portion 14 to the twisted rod in any suitable manner to close
the end of the tubular membrane 4 and provide a sharp point 15
whereby the device itself may be entered into the body of a
patient. The twisted bar 13 is secured at its proximal end to the
cannula 1 in a known manner. This bar 13 has a greater solid
cross-sectional area than has heretofore been obtained by utilizing
a cannulated end portion with slots or holes through the wall
thereof leading to the lumen.
Accordingly, it will be noted that the instant invention comprises
a catheter device for sampling gases in the blood or tissue of a
patient, and which is of a diameter smaller than heretofore
utilized, which provides ample diffusion area, and which is itself
insertable into the body of a patient without aid from some other
instrument to provide an entryway.
* * * * *