Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a sheath or cannula and particularly
to a cannula usable with angiographic catheters.
In certain angiographic studies, the angiographer uses a
procedure known as the Desilets-Hoffman procedure to do a multiple
study. This procedure is described in The American Journal of
Roentgenology, Radium Therapy and Nuclear Medicine, Vol. 97, No. 2,
pages 519-522, "A New Method of Percutaneous Catheterization" by
Donald T. Desilets, Richard B. Hoffman and Herbert D. Ruttenberg.
The angiographer obtains access to the patient's blood vessel by
inserting a hollow needle through the skin and into the lumen of the
blood vessel. A guidewire is passed through the needle and advanced
through the artery or vein into the organ to be studied. The needle
is removed leaving the guidewire in the organ. A sheath and dilator
are advanced over the wire into the vessel and the dilator is
removed along with the guidewire. The angiographer can then conduct
the multiple studies by inserting various types of catheters into
the vessel through the sheath.
In order to avoid excessive bleeding and to ensure against the
possibility of an a:ir embolism, this technique involves the
physician occluding the passage through the sheath during catheter
changes. When such occluding is performed manually there is always
the possibility that it will not be accomplished as quickly as
desired and will not be continuously effective for as long as
desired. A cannula valve is disclosed in U.S. Patent 4,000,739;
however, it is only intended to be effective in preventing blood
loss from the vessel. It is desirable that a hemostasis cannula be
provided which is effective in preventing air flow into the blood
vessel.
One embodiment of this invention might include a hemostasis
3~ cannula having a body with a passage therethrough adapted to receive
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a catheter. There is also provided first, second and third disc-like
gaskets mounted in the passage. The first gasket has a slit therein. The
second gasket has a hole therein and the third gasket has a flapper therein.
The passage through the body has one end adapted to be open to atmosphere
and an opposite end to be in communication with a patient's blood vessel.
The first gasket is in contact with the second gasket and the second gasket
is in contact with the third gasket. The first gasket is located toward
the open-to-atmosphere end of the body and the third gasket is located
toward the other end with the second gasket being positioned between the
first and second gaskets. Th flapper is arranged and disposed to open only
toward the other end. The second gasket is operable to maintain a sealing
relationship with a catheter contained in the passage. When the catheter
is not contained in the passage, the first and second gaskets are operable
to close the passage against flow into the blood vessel and the second and
third gaskets are operable to close the passage against flow out of said
blood vessel.
Objects of this invention are to provide an improved hemostasis
cannula and to provide a hemostasis cannula which is effective in preventing
air flow into the blood vessel.
Figure 1 is a cross-sectional view taken axially of the hemostasis
cannula of the present invention.
Figure 2 is an exploded partially cut-away view of the embodiment
of Figure 1.
Figure 3 is a side elevatiollal view of the calmula having a dilator
unit and a wireguide therein.
Figure 4 is a view similar to Figure 3 showing the cannula in position
in the lumen of a blood vessel with a catheter enclosed therein.
~eferring now more particularly to the drawings, there is illustrated
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a hemostasis cannula which includes a body 10 having a passage 11 therethrough
adapted to receive a catheter. The body is
2a
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made up of a member 12 having two externally threaded surfaces 15
and 16. A cap 17 is threaded down on the member 12 on the threads
15 and is glued in place by a suitable cement or the like. Between
the cap 17 and the member 12 are received three gaskets 20, 21 and
22. The unstressed thickness of the gaskets 20, 21 and 22 is such
that they are compressed between the cap 17 and the member 12.
Referring to FI&. ~, it can be seen that the first gasket 22 has
a slit 25 therein which extends through the axis of the gasket and
is straight or rectilinear extending all the way through one edge 26
of the gasket. The second or intermediate gasket 21 has a round or
cylindrical hole 27 located axially in the gasket. The hole 27 has
the approximate size of or slightly smaller size than the catheter
being used with the hemostasis cannula. Thus the gasket 21
functions to engage and seal between the gasket and the catheter
blocking off any opening through the gaskets 20, 21 and 22 and
blocking the passage 11.
The third gasket 22 has a flapper valve or member 30 formed
therein by means of a C-shaped slot 31. When the catheter ls placed
through the gaskets 20, 21 and 22, the slit 25 is caused to separate
by the catheter which then passes through the hole 27 and forces the
flapper 30 rightwardly as viewed in FIG. 2 opening the passageway 11
so that the catheter can be moved through the hemostasis cannula
into the blood vessel as shown in FIG. 4.
The cannula body 10 also includes an internally threaded member
32, the threads of which are suitable for mating engagement with the
thread 16 on the member 12. The function of the member 32 is to
receive and fix or hold the flexible tubing 35 to the body 10. In
the assembly procedure, adhesive or cement is placed on the flexible
tubing 35 and between the member 12 and 32 for fixing the tubing and
J~ members together. The flexible tubing 35 has a flar.ed end 36 which
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is fixed between the tapered surfaces 37 and 40 of the members 16
and 32.
The body 10 is provided with a port 45 which communicates with
the passage 11 between the gaskets and the flexible tube 35 for
introducing fluids into the patient's blood vessel. So that blood
does not flow out the flushing port 45, the pbysician normally
maintains a positive pressure of flushing fluid through the flexible
tubing 46 attached to the projection 47 by means of the annular
ridges 50. The flexible tubing 35 is further secured to the body 10
by means of shrinkable tubing 51 which is secured about the collar
52 and the annular ridges 55 on the collar 52 as well as the
flexible tubing 35. As seen in FIG. 3, a hollow plastic dilator 56
having an outer diameter substantially equal to that of the catheter
57 may be positioned in the passage 11 with the tapered end 60 of
the dilator extending past the distal end of the tube 35. After the
cannula has been inserted in the blood vessel over the guidewire 61
and the dilator 60, the dilator and guidewire may be removed and
discarded.
The gaskets 20, 21 and 22 are preferably made of silicone rubber
and are housed within a sufficiently small space so as to cause them
to be squeezed together. Thus in one specific embodiment of the
invention the thickness of the unstressed individual gaskets is
.032" totaling to .Og6" thickness for the three unstressed gaskets.
The gaskets however are squeezed within a spacing of .064" which is
the spacing betwen the surface 80 of the member 12 and the inside
surface 81 of the screwed down top 17. In the same preferred
embodiment of the invention there are two sizes of hole 27. For a
French size 3, 4 and 5 catheter, the hole 27 has an I.D. of .030".
For a French size of 6, 7, and 8, the hole 27 has an I.D. of .060".
J~ The various parts 17, 12 and 32 are constructed of a suitable rigid
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plastic material.
In operation, a hollow needle is used to subcutaneously enter
the vessel. When the lumen 62 of the vessel has been penetrated,
the guidewire 61 is threaded into the needle and blood vessel and
the needle is removed. The hollow plastic dilator 60 is now
threaded through the passage 11 of the cannula and is slipped over
the guide 61. The physician then dilates the hole through the
vessel wall by maneuvering the tapered end 60 of the dilator 56 and
introduces the entrance tube 35 into the vessel lumen 62. Note the
O.D. of the dilator at its constant diameter portion is close to the
O.D. of the flexible tubing 35 so that tubing 35 is guided through
the wall of the vessel by the dilator. The cannula is then taped in
position on the body of the patient, and, with the feed tube 46
fastened to the projection 47, and while maintaining a slow flow of
heparin saline solution into the pasage 11 through the tube 46, the
physician withdraws the dilator 56 and the guide 61. At this point
the slit 25 in the gasket 20 and the flap 30 in the gasket 22 both
close. The flap 30 resting in the gasket 21 resists the force
exerted by the patient's blood pressure and prevents blood loss.
The closure of the slit 25 insures that no air passes through the
opening 70 in the cap 17 through the gaskets into the passage 11.
Thus the present device not only preven~s blood loss but also
insures against the possibility of an air embolism.
The catheter 57 is now introduced through the opening in the cap
17 and passes through the gaskets. It is guided through the body 11
and the flexible tubing 35 by the tapered surfaces 71 and 72. The
catheter finally passes ioto the l~men 62 of the blood vessel. The
annular gasket 21 forms a seal around the exterior of the catheter
57 aod prevents blood loss through the hole 70 in the cap. The
_j passage 11 is constantly flushed by a flow of heparin saline
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solution introduced through the port 45 and the tubing 46 in order
to prevent clotting. When the catheter 57 has been maneuvered into
position, radiopaque fluid is injected through the catheter and
X-ray photographs may be taken of the radiopaque configuration of
the organ being studied.
When multiple studies are indicated, or if a catheter has not
been positioned correctly, the catheter may be easily removed and
replaced with a further catheter. Also a guidewire may be used by
passing it through the cannula if needed. Because the gaskets 20
and 22 close at the time of removal of the catheter, no bleeding is
experienced by the patient and no air is allowed to enter into the
patient's blood vessel in the event that the pressure externally of
the cannula is greater than the pressure internally of the blood
vessel.
While the invention has been illustrated and described in detail
in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
