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Claims  |
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I claim:
1. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person; and
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon,
said first member includes a hole in the distal tip thereof.
2. The apparatus of claim 1 wherein said first member includes a first
plurality of holes near the distal end thereof.
3. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person; and
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon,
said first member includes a first plurality of holes near the distal end
thereof, said means for preventing is that said first balloon, when
inflated, completely occludes said first holes and occupies the entire
intraluminal space in the distal end of said first member to the exclusion
of any entrapped air.
4. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person;
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon; and
(d) means, including a flexible tubular passageway in said first member
having an inlet opening near the proximal end thereof and an outlet
opening near the distal end thereof, for infusing a solution upon
insertion of the distal end of said first member into the circulatory
system of a person during cannulation.
5. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person; and
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon,
said first member includes a first plurality of holes near the distal end
thereof, said means for preventing includes means for allowing liquid to
wash freely across and through the unobstructed portion of the distal end
of said first member upon insertion of the distal end into the circulatory
system of a person.
6. The apparatus of claim 5 wherein the means for preventing and for
allowing is that the most distal portion of said first balloon, when
inflated, extends to a point between the most distal portion and the most
proximal portion of the holes near the distal end of said first member.
7. The apparatus of claims 3, 4 or 5 wherein said first member includes a
hole in the distal tip thereof.
8. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof, said first member
further including at least one second hole therein spaced apart axially
from the first hole;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person;
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon;
(d) a second inflatable balloon on the inside wall of said first member
adjacent to the second hole therein, said second balloon, when inflated,
completely occluding the second hole and lumen of said first member and
preventing the entrapment of any air therein; and
(e) means including a second flexible tubular passageway communicating with
said second balloon for readily inflating and deflating said second
balloon independently of said first balloon.
9. A balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique comprising:
(a) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including a
first plurality of holes near the distal end thereof, said first member
further including at least one second hole therein spaced apart axially
from the first holes;
(b) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person, said means for preventing further including means for allowing
liquid to wash freely across and through the unobstructed portion of the
distal end of said first member upon insertion of the distal end into the
circulatory system of a person;
(c) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon;
(d) a second inflatable balloon on the inside wall of said first member
adjacent to the second hole therein, said second balloon, when inflated,
completely occluding the second hole and lumen of said first member and
preventing the entrapment of any air therein; and
(e) means including a second flexible tubular passageway communicating with
said second balloon for readily inflating and deflating said second
balloon independently of said first balloon.
10. The apparatus of claim 9 wherein said first member includes a second
plurality of holes therein spaced apart axially from the first holes.
11. The apparatus of claim 10 wherein the first and the second holes are
spaced apart along said first member a distance of between about 5 cm. and
about 15 cm.
12. The apparatus of claim 11 wherein the distance separating the first and
the second holes is sufficient to allow positioning of the distal end of
said first member and the first holes therein in the inferior vena cava of
a human heart while the second holes are positioned in the right atrium of
the heart during cardiac cannulation.
13. The apparatus of claim 10 wherein the distance separating the first and
the second holes is sufficient to allow positioning of the distal end of
said first member and the first holes therein in the left ventricle of a
human heart while the second holes are positioned in the left atrium of
the heart during cardiac cannulation.
14. The apparatus of claim 13 additionally comprising means, including a
third flexible tubular passageway in said first member having an inlet
opening near the proximal end thereof and an outlet opening near the first
and the second holes in said first member, for infusing a solution into
the circulatory system of a person during cannulation.
15. The apparatus of claim 14 wherein the means for preventing and for
allowing is that the most distal portion of said first balloon, when
inflated, extends to a point between the most distal portion and the most
proximal portion of the first holes near the distal end of said first
member.
16. The combination comprising:
(a) a heart-lung machine means; and
(b) the cannula apparatus of claim 15 connected to said machine means.
17. The combination comprising:
(a) a heart-lung machine means;
(b) a balloon-tipped extracorporeal cannula apparatus suitable for use in a
cardiac cannulation technique connected to said machine means, said
cannula apparatus comprising:
(1) a first elongated and flexible tubular member having a proximal and a
distal end, the proximal end being open, said first member including at
least one first hole near the distal end thereof;
(2) a first inflatable balloon on the inside wall of said first member
adjacent to the first hole therein, said first balloon, when inflated,
completely occluding the lumen of said first member and including means
for preventing the entrapment of any air near the distal end of said first
member upon insertion of the distal end into the circulatory system of a
person; and
(3) means, including a flexible tubular passageway communicating with said
first balloon, for readily inflating and deflating said first balloon.
18. A method for inserting a cannula during a cardiac cannulation technique
comprising:
(a) filling the lumen of a cannula with liquid, the cannula including a
first elongated flexible tubular member defining the lumen therein and
having a proximal and a distal end, the proximal end being open, said
first member including at least one first hole near the distal end thereof
and at least one second hole spaced apart proximally therefrom, said
filling comprising filling the lumen to the second hole in the first
member;
(b) occluding the partially filled lumen of the cannula near the second
hole, said occluding comprising inflating a second balloon on the inside
wall of the first member adjacent to the second hole therein;
(c) filling the remaining portion of the lumen distally from the second
inflated balloon;
(d) occluding the filled lumen of the cannula near the first hole at the
distal end thereof, said occluding comprising inflating a first balloon on
the inside wall of the first member adjacent to and proximal of the first
hole therein, said occluding further being as to prevent the entrapment of
any air near the distal end of the first member upon insertion thereof
into the circulatory system of a person;
(e) inserting the filled and occluded cannula into the circulatory system
of a person through a prepared incision, said inserting including
positioning the first and the second hole in the areas to be cannulated;
and
(f) unoccluding the second hole in the cannula thereby allowing liquid to
flow between the cannula and the circulatory system through the second
hole, said unoccluding comprising deflating the second balloon on the
inside wall of the cannula.
19. The method of claim 18 wherein said first member includes a first
plurality of holes near the distal end thereof and a second plurality of
holes spaced proximally therefrom.
20. The method of claim 19 wherein said occluding comprises completely
occluding the first holes and occupying the entire intraluminal space in
the distal end of the first member to the exclusion of any entrapped air.
21. The method of claim 19 wherein said occluding further comprises
allowing liquid to wash freely across and through the unobstructed portion
of the distal end upon insertion thereof into the circulatory system of a
person.
22. The method of claim 21 wherein said unoccluding further comprises
deflating the first balloon on the inside wall of the cannula thereby
allowing liquid to flow between the cannula and the circulatory system
through both the first and the second holes in the first member.
23. The method of claim 22 additionally comprising infusing a solution into
the cannulated areas in the circulatory system of the person during the
cannulation procedure. |
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Claims |
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Description |
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This invention relates to methods and apparata used in cannulation
techniques, and particularly, to an improved cannula apparatus and method
for its insertion suitable for use in a cardiac cannulation technique.
A cannula, or catheter as it may be called, is generally recognized as an
elongated and flexible tube that may be inserted into a person's body in
order to withdraw or inject various fluids. The prior art is replete with
such cannulas and catheters, as well as with methods for their insertion
and use.
The general use of inflatable ballons with such cannulas and catheters is
also known in the art. In one instance, commonly referred to as a "bag"
catheter, an externally attached balloon or "bag" is used to hold the
catheter in place after insertion in order to allow prolonged or periodic
withdrawal or injection of fluids into the body. A common use for such
"bag" catheters, as disclosed in Rocchi et al., U.S. Pat. No. 3,331,371,
is to insert the catheter by way of the urethra into a person's bladder in
order to withdraw fluid from the bladder over a period of time. Another
example of an externally attached inflatable balloon or collar used to
stabilize the position of the cannula following insertion is found in
Shinnick et al., U.S. Pat. No. 3,680,544, which discloses a transthoracic
cannula-type device useful in cardiopulmonary resuscitation.
In other instances, inflatable balloons have been positioned inside the
luminal cavity in the cannula or catheter in order to achieve a desired
result. In Kim, U.S. Pat. No. 2,919,697, such an intraluminal inflatable
balloon was used for the same purpose as above described, i.e., for
anchoring the standard catheter drainage tube in the body after insertion.
The above Rocchi reference, on the other hand, uses the intraluminal
balloon or ball to completely cover the fluid holes in the catheter and
thereby control the flow of fluid therethrough.
A rapidly-growing area of cannula technology concerns the technique of
cardiac cannulation and the use of artificial heart-lung machine means to
facilitate intricate and prolonged operations on the cardiac, pulmonary
and circulatory systems. During such operations, cannulas which are
connected to the artificial heart-lung machine means are first properly
inserted through prepared incisions into the arterial and venous systems
adjacent the heart, and even into the intracardiac chambers as well. Once
properly positioned and in operation, the blood of the person is withdrawn
or siphoned through the venous cannulas and pumped through the arterial
cannulas back into the circulatory system by the artificial heart-lung
machine means. The heart and lungs of the person can thereby be
effectively bypassed, thus allowing the surgeon to operate on the heart.
A major problem encountered in all such cardiac cannulation techniques
involves the introduction of air into the circulatory system during the
insertion and positioning of the various venous, arterial and intracardiac
cannulas. In this regard, the avoidance of any such introduction is
extremely important because of the danger of stroke or other adverse
effects such air may have on the circulatory system.
The present state of the art provides two possible methods for avoiding any
such introduction of air during cardiac cannulation. One method involves
first inserting the distal end of the cannula into the circulatory system
while the tubing connecting the cannula to the heart-lung machine means is
then vented by manipulating a drain line near the proximal end of the
cannula thereby permitting the cannula to fill with the patient's blood.
This method, however, does not prevent the possible introduction of air
into the blood stream during initial insertion of the distal end of the
cannula. In addition, it requires the extra steps of manipulating both the
venting line and the external clamp, and cannot prevent the probable
entrapment of air in the tube between this venting line and the clamp
itself.
A second method of cannula insertion practiced in the present art involves
first holding the cannula upright and filling it either with a serum or
with blood through the plurality of holes near its closed distal tip.
Then, the surgeon rapidly inserts the distal end of the cannula into the
prepared incision in the circulatory system in order to avoid excessive
spillage of the fluid, if at all possible. This method has its
shortcomings both because of the mess created by the spilling fluid and
because as the fluid empties, air may be again allowed into the cannula
and later introduced into the circulatory system.
SUMMARY OF THE INVENTION
One embodiment of the present invention comprises a balloon-tipped
extracorporeal cannula apparatus suitable for use in a cardiac cannulation
technique including a first elongated and flexible tubular member having a
proximal and a distal end, the proximal end being open, said first member
including at least one first hole near the distal end thereof, a first
inflatable balloon on the inside wall of the first member adjacent to the
first hole therein, and means including a flexible tubular passageway
communicating with the first balloon for readily inflating and deflating
the first balloon. When inflated, this first balloon completely occludes
the lumen of the first member and includes means for preventing the
entrapment of any air near the distal end of the first member upon
insertion of the distal end into the circulatory system of a person.
The above embodiment thus permits cannulation of the heart and adjacent
vessels without the risk of trapping any air near the distal end of the
cannulas and thereby eliminates any possibility of introducing this air
into the circulatory system during the cannulation procedure.
One mode of practicing this above embodiment includes a first plurality of
holes near this distal end, the means for preventing includes means for
allowing liquid to wash freely across and through the unobstructed portion
of the distal end of the first member after its insertion. This is
accomplished by positioning the intralumenal balloon so that the most
distal portion of the balloon, when inflated, extends to a point between
the most distal portion and the most proximal portion of the holes nearest
the distal end of the first member. This first balloon is further
sufficiently large and extends along the inside wall of the first member a
sufficient distance so that, when inflated, it completely occludes both
the lumen of the first member and all more proximally positioned holes
therein. This positioning eliminates both the need for manipulating any
external venting line or tubing clamp and the mess and spillage of fluid
characteristic of prior art methods. It further specifically prevents the
entrapment of any air either distal of the holes in the distal tip of the
first member or proximal of the holes between this first inflated balloon
and the plurality of holes themselves, as would result with the use of
catheters such as the ones disclosed in the Rocchi and Kim references.
This above positioning of the intraluminal balloon can also provide other
advantages by only partially obstructing the holes near the distal end of
the cannula, particularly where vessel or chamber obstruction is of major
concern. For instance, the distal tip of the cannula may become wedged or
stuck in a side vein or artery or in a confined area in an inner chamber
of the heart during cannulation and thus threaten to occlude or block the
vessel or chamber when such occlusion is both unexpected and not
desirable. With the above mode, this result may be avoided because blood
may still be able to wash or flow freely across and through the
unobstructed portion of the distal end of the cannula after its insertion
and before the balloon is deflated and the siphoning, or pumping, action
begun. This provides a major advantage over such balloon catheters as
disclosed in Rocchi, which completely obstruct the fluid holes in the
catheter when the balloon is inflated thereby negating any possible bypass
for the flow of blood if the cannula becomes unavoidably stuck.
In a second mode of practicing the above embodiment, this first member
includes both a first plurality of holes including a hole in the distal
tip thereof and a second plurality of holes spaced apart proximally from
the first holes along this first member. A second inflatable balloon is
then positioned on the inside wall of the first member adjacent to the
second holes therein. This second balloon, when inflated, completely
occludes both the second holes and the lumen of the first member itself.
The provision of the second holes permits the drainage or injection of
blood from or into two areas adjacent the heart, e.g., when the tip of the
cannula is placed in the inferior vena cava with the second more proximal
holes positioned in the right atrium. A second example is when the tip of
the cannula is positioned in the left ventricle whereas the second more
proximal holes are positioned in the left atrium to allow drainage from
both areas. In addition, a second flexible tubular passageway can be
provided in the first member having an inlet opening near the proximal end
thereof and an outlet opening near the distal end thereof, this second
passageway being suitable for infusing any variety of solutions into the
heart or the adjacent vessels upon insertion of the distal end into the
circulatory system of a person during a cannulation procedure.
Still a third mode of practicing the above embodiment stresses the concern
for preventing entrapped air from entering the circulatory system while
minimizing any concern over vessel or cavity obstruction. In this third
mode, the first balloon, when inflated, completely occludes both the first
plurality of holes and the lumen of the first member while also preventing
the entrapment of air in the distal tip. This can be accomplished in two
ways. First, if the first member is without a hole in the distal tip, the
first balloon must expand, or inflate, a sufficient amount to fully occupy
this most distal intraluminal space while displacing any potentially
entrapped air. If the first member does include a hole in the distal tip
thereof, however, this first balloon must expand a sufficient amount to
fully occupy the most distal intraluminal space and protrude from the
distal tip hole thereby again preventing the introduction of any entrapped
air into the circulatory system. This mode is useful in cannulating larger
cavities in the heart, such as the left ventricle, which are without
restrictive vessels draining in or out of the area thereby decreasing the
concern over trauma caused by possible obstruction.
A second embodiment of the present invention comprises the method for
inserting a cannula during a cardiac cannulation technique comprising
filling the lumen of the cannula apparatus of the above embodiments with
liquid, occluding the filled lumen by inflating the balloon(s) adjacent
the hole(s) therein, inserting the distal end of the filled and occluded
cannula into the circulatory system of a person through a prepared
incision and then unoccluding the lumen of the cannula by deflating the
balloon(s) thereby allowing liquid to flow between the cannula and the
circulatory system.
One object of the present invention is therefore to provide a
balloon-tipped extracorporeal cannula and method for its insertion that
prevent the introduction of any trapped air into the circulatory system of
the patient during cannulation.
Another object of the present invention is to provide a method for
inserting a cannula during a cardiac cannulation which avoids the mess of
liquid spillage and eliminate the need for external clamps or for venting
trapped air in the cannula while preventing the possible introduction of
such trapped air into the circulatory system.
Related objects and advantages of the present invention will be apparent
from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmented side elevation of the balloon-tipped extracorporeal
cannula comprising a perferred embodiment of the present invention with a
portion broken away to reveal the partially collapsed balloon.
FIG. 2 is a partial side elevational of the cannula in FIG. 1 with a
portion broken away to reveal the balloon when inflated.
FIG. 3 is a cross-sectional view of the cannula in FIG. 1 taken along line
3--3.
FIG. 4 is a cross-sectional view of the cannula in FIG. 2 taken along line
4--4.
FIG. 5 is a reduced representation of four balloon-tipped extracorporeal
cannulas of the present invention, as shown in FIG. 1, in use during a
cardiac cannulation.
FIG. 6 is a part-sectional view of the distal end of the cannula in FIG. 2
positioned in the inferior vena cava adjacent a person's heart during a
cardiac cannulation.
FIG. 7 is a partial side elevation of a modified cannula apparatus in
accordance with one embodiment of the present invention, with a portion
broken away to reveal the first balloon when inflated.
FIG. 8 is a fragmented side elevation of a second modified cannula
apparatus in accordance with one embodiment of the present invention, with
a portion broken away to reveal the partially collapsed first and second
balloons.
FIG. 9 is a cross-sectional view of the cannula in FIG. 8 taken along line
9--9.
FIG. 10 is a representation of a cannula similar to the one in FIG. 8 in
use during a cardiac cannulation, with the first holes positioned in the
left ventricle of the heart and the second proximal holes positioned to
drain blood from the left atrium.
FIG. 11 is a partial side elevation of a third modified cannula apparatus
in accordance with one embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For the purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiments illustrated in
the drawings and specific language will be used to described the same. It
will nevertheless be understood that no limitation of the scope of the
invention is thereby intended, such alterations and further modifications
in the illustrated devices, and such further applications of the
principles of the invention as illustrated therein being contemplated as
would normally occur to one skilled in the art to which the invention
relates.
Referring now to FIG. 1, the balloon-tipped cannula 10 comprising a
preferred embodiment of the present invention is therein depicted. Cannula
10 includes a first elongated and flexible tube 11 which has both a
proximal end 12 and a distal end 13. The proximal end of cannula 10 is
open to allow the cannula to be attached to various secondary tubing which
then connects the cannula to the desired equipment, such as the heart-lung
machine means 14 in FIG. 5. Distal end 13, on the other hand, has a closed
and thickened distal tip 15 and includes a plurality of holes 16 near this
distal tip which allow fluid to flow between the lumen 17 of cannula 10
and the circulatory system of the person.
As stated above, tube 11 of the preferred embodiment is made of a flexible
material, such as rubber or polyvinyl. It may also include a spiraling
wire 18 which is molded into the cannula wall 24. This wire 18 reinforces
the central portion of cannula 10 thereby facilitating easy handling and
preventing any possibility of the cannula collapsing or being pinched shut
and thus closing off the flow of blood to or from the patient. Other ways
of reinforcing the tubular body of a cannula are known in the art and will
adapt equally well to the present invention. In addition, no reinforcement
may be needed if the tube material is sufficiently strong.
The dimensions of tube 11 may vary greatly according to the person's age
and size, the number of cannulas used in the cannulation technique and the
specific manufacturer of the cannulas used. The external cross-sectional
diameter of the tube 11 may thus vary from about 1 cm. to about 2 cm. at
its widest point, tube 11 of the preferred embodiment being about 1.5 cm.
in diameter.
A first inflatable balloon 21 is positioned on the inside wall of tube 11
adjacent to and proximal of the holes 16. A second elongated and flexible
tube 22 is connected to inflatable balloon 21 through an orifice or
opening 23 in the cannula wall 24. Tube 22 then connects the balloon 21 to
a supply of fluid (not shown) which is used to inflate and deflate the
balloon during use of the cannula 10. Air may be used as a satisfactory
inflating substance, however, it is desirable to use a liquid such as a
saline solution because of the possible danger of a leak developing in the
balloon which then could introduce air into the circulatory system of the
person.
Although various fluid supplies and means of inflating and deflating
balloon 21 may be used in conjunction with the present invention, in the
preferred embodiment tube 22 connects to a female attachment or adapter 19
which receives a nipple tip syringe (not shown). This syringe is used to
inject or withdraw fluid through tube 22 thereby inflating and deflating
the balloon.
In constructing a balloon-tipped extracorporeal cannula pursuant to this
embodiment, inflating tube or passageway 22 may extend completely along
the inside or outside of the cannula tube 11. However, cannula 10 of the
preferred embodiment incorporates the inflating tube or lumen 22 into the
cannula wall 24 through the major portion of tube 11, as better shown in
FIG. 3. Tube 22 of the preferred embodiment is thereby also protected by
reinforcing wire 18 before it finally exits the cannula wall near the
proximal end 12 of tube 11.
When deflated, collapsible balloon 21 lies flush against the inside wall of
tube 11 thereby allowing fluid to flow freely through cannula 10 with a
minimal amount of turbulence. The caliber or size of the deflated balloon
21 as it lies against the wall is such that it provides no appreciable
blockage of the lumen cavity 17 or the fluid passing therethrough. In
FIGS. 1 and 3, balloon 21 is shown not completely deflated for the
convenience and understanding of the reader and thus obstructs the lumen
17 substantially more than when fully deflated.
When inflated, as shown in FIGS. 2, 4, and 6, balloon 21 completely
occludes the lumen 17 of cannula 10. The most distal portion 25 of the
balloon 21 also extends to a point between the most distal portion and
most proximal portion of the holes 16 near the distal end of tube 11. FIG.
4 depicts a cross-sectional view of cannula 10 in FIG. 2 taken at the most
proximal portion of the holes 16. As it reveals, the inflated balloon
completely occludes the cannula lumen at that point thereby preventing the
flow of any fluid through the cannula. More importantly, by occluding the
lumen 17 right up to the holes 16, the inflated balloon also prevents the
entrapment of any air in the tube 11 proximal of holes 16 and thereby
avoids the possible introduction of any such entrapped air into the
circulatory system upon insertion of the cannula.
As previously discussed, an additional feature of the balloon-tipped
extracorporeal cannula of the preferred embodiment is that the inflated
balloon only partially obstructs the holes 16 near the distal end 13 of
the cannula. Therefore, no air can be trapped in the closed distal tip
during insertion, and the person's blood may be able to wash or flow
across and through the unobstructed portion of the distal end of tube 11
if it becomes wedged or stuck in a vessel or chamber after its insertion
and prior to deflation of the balloon 21. This minimizes the possibility
of interference with normal blood flow prior to initiating the artificial
heart-lung action and thus provides less chance of vessel obstruction
impairing the flow of blood through the circulatory system. FIG. 6 depicts
a venous cannula 10 of the present invention positioned in an inferior
vena cava 20 during a cardiac cannulation and prior to deflation of the
balloon. The blood is flowing in the direction of arrow 20'.
A second embodiment of the present invention comprises a method of
inserting balloon-tipped extracorporeal cannula 10 into a person's
circulatory system during a cardiac cannulation technique. The first step
in this method involves filling the lumen 17 of the cannula 10 with a
fluid. For this purpose, the fluid may be either blood or a compatible
electrolytic solution such as a saline solution and the filling may be
accomplished through either the proximal or distal end of the cannula. In
the preferred embodiment, the cannula 10 is filled with a saline solution
through the holes 16 near the closed distal tip.
The next step is occluding the lumen 17 near the holes 16 at its closed
distal tip 15 by inflating balloon 21. The distal end of the filled and
occluded cannula 10 is then inserted into the circulatory system of the
person through a prepared incision. And lastly, the lumen 17 is unoccluded
by deflating balloon 21 thereby allowing fluid to flow between the cannula
and the circulatory system of the person.
FIG. 5 depicts the preferred method and balloon-tipped extracorporeal
cannula 10 of the present invention in use during a cardiac cannulation.
Venous cannulas 26 and 27, constructed according to the present invention,
are first positioned in the superior and inferior vena cava, respectively.
An intracardial cannula 28 is also positioned inside the left ventricle of
the heart in order to decompress the heart and keep the volume of blood in
it minimal thereby preventing any possibility of the heart distending
during the operation. These cannulas are in turn connected through tubing
31, 32 and 33, respectively, to the input side of a heart-lung machine
means 14. An arterial cannula return line 34 is then positioned in the
aorta or femoral artery in order to recirculate the blood from the
heart-lung machine means 14 through tubing 35 and back into the
circulatory system of the person.
In practice, both the number and location of the cannulas used in a cardiac
cannulation technique can vary according to a variety of factors, such as
the specific type of operation involved. In the preferred embodiments,
four cannulas are used in order to assure proper and complete cannulation.
The cannulas are first properly inserted into the circulatory system
according to the above-described method. Then, when all four are properly
positioned, the balloons are deflated and the siphoning and recirculating
action through the heart-lung machine means 14 is begun. At this time, the
surgeon can operate on the person's heart, lungs or adjacent vessels while
the machine 14 artificially maintains the heart and lung functions. When
the operation is completed, the cannulas are again occluded by inflating
the intraluminal balloons or clamping them thus allowing the person's
heart and lungs to resume their normal functions.
Turning now to FIG. 7, a partial view of a modified cannula 36 in
accordance with the present invention is therein depicted. Specifically,
cannula 36 is substantially similar to cannula 10 of the preferred
embodiment as described above, with but a few modifications. First, the
distal end 37 of flexible tubular member 38 includes a hole 41 in the
distal tip thereof.
Second, cannula 36 includes additional holes 42 near the distal end 37 of
the cannula. First balloon 43 is constructed and positioned similar to
preferred cannula 10 and, upon inflation, extends to a point between the
most distal portion and the most proximal portion of the holes 42 nearest
the distal tip to thereby prevent the entrapment of any air in the distal
end of the cannula during insertion into the circulatory system of a
person. First balloon 43, when inflated, also completely occludes the
lumen of first member 38 and further blocks, or occludes, the more
proximal holes 42 near distal end 37. In this way, no air can be trapped
in the distal end 37 during insertion of the cannula.
In addition, once inserted and first balloon 43 is deflated, these
additional holes permit the blood to flow more freely through the distal
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