U.S. patent application number 10/742452 was filed with the patent office on 2004-10-28 for appliance for cannulation of a blood vessel.
Invention is credited to Frerichs, Heiko, Klietsch, Dietmar, Matheis, Georg, Sandmann, Axel.
Application Number | 20040215142 10/742452 |
Document ID | / |
Family ID | 32404372 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040215142 |
Kind Code |
A1 |
Matheis, Georg ; et
al. |
October 28, 2004 |
Appliance for cannulation of a blood vessel
Abstract
The present invention relates to an appliance for cannulation of
a blood vessel with a cannula which, after introduction into the
vessel, is in fluidic communication with the vessel. At least one
means is also provided to permit a controlled division of the blood
into a first subsidiary stream which leaves the vessel through the
cannula, and a second subsidiary stream which continues to flow
through the vessel.
Inventors: |
Matheis, Georg;
(Burladingen, DE) ; Frerichs, Heiko; (Hechingen,
DE) ; Sandmann, Axel; (Oberried, DE) ;
Klietsch, Dietmar; (Herrenberg, DE) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
32404372 |
Appl. No.: |
10/742452 |
Filed: |
December 19, 2003 |
Current U.S.
Class: |
604/103.08 |
Current CPC
Class: |
A61M 1/3666 20130101;
A61M 1/3653 20130101; A61M 2025/1095 20130101; A61M 1/3659
20140204 |
Class at
Publication: |
604/103.08 |
International
Class: |
A61M 029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2002 |
DE |
102 61 575.6 |
Claims
Therefore, what is claimed, is:
1. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the
vessel.
2. The appliance of claim 1, wherein the subsidiary stream
remaining in the vessel can be guided via the means past the
cannula.
3. The appliance of claim 2, wherein the means is a balloon which
surrounds the cannula and which has a surface with at least one
groove-like depression.
4. The appliance of claim 3, wherein the surface with the at least
one groove-like depression faces towards the vessel and/or the
cannula.
5. The appliance of claim 2, wherein the means is at least one
balloon which surrounds the cannula in sections in such a way that
at least two ends of the balloon pointing in the circumferential
direction are located at a circumferential distance from one
another.
6. The appliance of claim 5, wherein two balloons are provided
which surround the cannula in sections.
7. The appliance of claim 3, wherein the balloon is dilatable.
8. The appliance of claim 4, wherein the balloon is dilatable.
9. The appliance of claim 3, wherein the balloon is not
dilatable.
10. The appliance of claim 4, wherein the balloon is not
dilatable.
11. The appliance of claim 1, wherein the subsidiary stream
remaining in the vessel can be guided first into the cannula and
then out of it via the at least one means.
12. The appliance of claim 11, wherein the means is an outlet in
the cannula.
13. The appliance of claim 12, wherein the outlet is an opening in
the cannula.
14. The appliance of claim 12, wherein the outlet is a tubular
portion on the cannula, which tubular portion is guided in the
vessel.
15. The appliance of claim 12, wherein the outlet is a cannula-like
portion on the appliance which portion is guided at least partially
outside the vessel.
16. The appliance of claim 12, wherein a balloon is additionally
provided which is arranged on the cannula between the point of
entry of the blood into the cannula and the outlet.
17. The appliance of claim 1, wherein means are additionally
provided for measuring at least one of the subsidiary streams.
18. The appliance of claim 2, wherein means are additionally
provided for measuring at least one of the subsidiary streams.
19. The appliance of claim 10, wherein means are additionally
provided for measuring at least one of the subsidiary streams.
20. The appliance of claim 1, wherein means are additionally
provided for Regulating the subsidiary streams.
21. The appliance of claim 2, wherein means are additionally
provided for regulating the subsidiary streams.
22. The appliance of claim 10, wherein means are additionally
provided for regulating the subsidiary streams.
23. The appliance of claim 17, wherein means are additionally
provided for regulating the subsidiary streams.
24. The appliance of claim 1, wherein the cannula has an external
diameter of ca. 5 to 30 French, in particular of 13 to 21
French.
25. The appliance of claim 1, wherein it is coated with a
biocompatible material.
26. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the vessel,
wherein the subsidiary stream remaining in the vessel can be guided
via the means past the cannula.
27. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the vessel,
wherein the subsidiary stream remaining in the vessel can be guided
via the means past the cannula, wherein the means is a balloon
which surrounds the cannula and which has a surface with at least
one groove-like depression.
28. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the vessel,
wherein the subsidiary stream remaining in the vessel can be guided
first into the cannula and then out of it via the at least one
means.
29. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the vessel,
wherein the subsidiary stream remaining in the vessel can be guided
first into the cannula and then out of it via the at least one
means, wherein the means is an outlet in the cannula.
30. An appliance for cannulation of a blood vessel with a cannula
which, after introduction into the vessel, is in fluidic
communication with the vessel, wherein at least one means is
provided to permit a controlled division of the blood into a first
subsidiary stream which leaves the vessel through the cannula, and
a second subsidiary stream which is continued through the vessel,
wherein the subsidiary stream remaining in the vessel can be guided
first into the cannula and then out of it via the at least one
means, wherein the means is an outlet in the cannula, wherein the
outlet is a tubular portion on the cannula, which tubular portion
is guided in the vessel.
31. A method for extracorporeal lung assist, comprising the steps
of canulating a blood vessel, preferably the femoral artery, with a
cannula, dividing in a controlled manner the blood flowing within
said vessel into a first subsidiary stream which leaves the vessel
through the cannula, and a second subsidiary stream which is
continued through the vessel, guiding said first subsidiary blood
stream through a lung assist device and then back into an ether
blood vessel, preferably into the femoral vein.
32. The method of claim 31, wherein said cannula is part of the
applicance of claim 1.
33. The method of claim 31, wherein said cannula is part of the
applicance of claim 26.
34. The method of claim 31, wherein said cannula is part of the
applicance of claim 28.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an appliance for
cannulation of a blood vessel with a cannula which, after
introduction into the vessel, is in fluidic communication with the
vessel, and also to the use of the appliance and to a method for
cannulation of blood vessels.
[0003] 2. Related Prior Art
[0004] Such appliances are already known in the medical field and
are used in many different medical indications.
[0005] For example, they are used in extracorporeal blood circuits,
for example for extracorporeal lung assist. This is necessary when
a patient's pulmonary function is impaired and the body's oxygen
supply is at risk. In this connection, apparatuses have now been
used for some time which, like a heart-lung machine in open-heart
surgery, can temporarily take over the function of the diseased
lung.
[0006] In temporary extracorporeal lung assist (ECLA),
extracorporeal membrane oxygenation (ECMO) has for many years been
an established treatment procedure in patients with acute severe
lung failure. As with the heart-lung machine, blood is removed from
one of the large vena cava, for example, via a wide-lumen cannula,
is driven through membrane lungs in the extracorporeal system by
means of a pump, and is then returned via a second cannula which is
positioned, for example, in the aorta.
[0007] In patients with good haemodynamic parameters, it is even
possible to create an arterio-venous shunt which allows a lung
assist device with low resistance to be used without pump. This
interventional lung assist (ILA) allows the gas exchange of the
lungs to be assisted extracorporeally, without use of machines, via
a lung assist device designed as a disposable product (see, for
example, Reng et al. "Pumpless extracorporeal lung assist and adult
respiratory distress syndrome", 2000, The Lancet 356: 219-220).
[0008] In the prior art, vessels are cannulated using cannulas
whose size or diameter is chosen in particular with reference to
the size of the femoral artery.
[0009] The cannula size is chosen in such a way that the area of
the lower extremity beyond the cannula is still supplied with
blood.
[0010] However, as a result of the overall trauma triggered, for
example, by high doses of medication, blood transfusions, septic
reactions, etc., there may be severe contractions of the arteries
in particular. With these contractions, the diameter of the vessels
becomes narrower, as a result of which the femoral artery closes
tightly around the arterial cannula. In this way, all of the blood
guided in the artery flows into the cannula and, via the cannula,
into the femoral vein of the other leg, which means that blood
supply to the distal areas of the leg with the arterial cannula is
no longer guaranteed. As a result of this undersupply of arterial,
oxygen-enriched blood, tissue necrosis takes place below the
cannulation site unless the depleted blood flow is detected and
treated in good time.
[0011] In the prior art, various attempts have been made to prevent
these complications. Thus, in "Technique to prevent limb ischemia
during peripheral cannulation for extracorporeal membrane
oxygenation", Perfusion 17: 427-428 (2002), Kasirajan et al.
briefly describe a method in which, in order to prevent ischaemia,
arterial reperfusion with concurrent distal venous drainage is
applied. To do this, two cannulas of different sizes are fitted in
each case into the femoral artery and into the femoral vein, and
the arterial and venous cannulas are in each case connected to one
another in a Y shape.
[0012] Moreover, in the publication entitled "Prevention of Lower
Extremity Ischemia during Cardiopulmonary Bypass via Femoral
Cannulation", Ann. Thorac. Surg. 63: 251-252 (1997), Salm describes
a technique for preventing ischaemia of the lower extremities in
which perfusion of the femoral artery is achieved using a stent
whose end is sutured laterally onto the artery.
[0013] However, these techniques have the disadvantages that the
insertion of the two further cannulas additionally damages and thus
irritates the vessels. Moreover, the method is made very
complicated by the use of four cannulas.
[0014] For general cannulation of vessels, the prior art also
includes balloon catheters with which vessels can be closed.
[0015] Wimmer-Greinecker et al., in "Complications of Port-Access
Cardiac Surgery", J. Card. Surg. 14: 240-245 (1999), describe
cannulation of the femoral artery and vein in connection with a
cardiopulmonary bypass, an endoaortic balloon clamp being
introduced via the arterial cannula. For open-heart surgery, after
the balloon has been inflated (and the aorta thus clamped), all the
blood is guided via the bypass.
[0016] In the prior art, a large number of balloon catheters are
also known with which it is possible to close vessels in a specific
manner. For example, in many cardiovascular operations, it is
possible to completely close a vessel by inflating the balloon so
that the latter bears against the vessel to be occluded.
[0017] However, in extracorporeal lung assist, for example, such
balloon catheters are not suitable because they completely close
the artery, as a result of which the flow of blood into the lower
extremities or into the areas below the cannulation site is
blocked, which, as has been mentioned above, may lead to ischaemia
and, consequently, to ischaemic tissue necrosis.
SUMMARY OF THE INVENTION
[0018] An object underlying the invention is therefore to make
available an appliance, of the type mentioned at the outset, with
which blood vessels can be cannulated and which can be used also in
extracorporeal lung assist without the danger of ischaemia of areas
lying below the cannulation site.
[0019] According to the invention, this object is achieved by the
fact that, in the appliance mentioned at the outset, at least one
means is provided to permit a controlled division of the blood into
a first subsidiary stream which leaves the vessel through the
cannula, and a second subsidiary stream which is continued through
the vessel.
[0020] The object underlying the invention is achieved completely
in this way.
[0021] With the present invention, it is possible to ensure that
blood guided in a vessel is not removed in its entirety from the
body via a cannula, but instead only a defined proportion of the
blood flowing in the vessel is removed. At the same time, means
provided according to the invention ensure that another portion of
the blood is continued in a controlled manner through the vessel.
In this way, the supply of blood and oxygen to areas situated below
the cannulation site is guaranteed.
[0022] Thus, the appliance according to the invention can be
advantageously used in extracorporeal lung assist, for example, the
at least one means ensuring that a controlled subsidiary stream of
blood is delivered to the extracorporeal circuit and a controlled
subsidiary stream of blood continues through the vessel.
[0023] The term "cannula" in the context of the present application
is to be understood as meaning any appliance which can be
introduced into a vessel and has a lumen. The cannula can include
various materials tried and tested in medical technology, for
example metals, polyurethane, etc. The cannula is preferably a
wire-reinforced polyurethane cannula.
[0024] The term "means" in the context of the present invention is
to be understood as any arrangement provided on the appliance and
making it possible to deliberately continue part of the blood
stream through the vessel.
[0025] According to one object of the appliance according to the
invention, it is preferable if the subsidiary stream remaining in
the vessel can be guided via the means past the cannula.
[0026] This has the advantage that not all the blood in the vessel
is guided into the cannula and thus removed from the vessel.
Instead, the means ensures that a subsidiary stream is deliberately
guided past the cannula and into areas situated below the
cannulation site. These areas can be supplied with blood and oxygen
in this way.
[0027] According to another object, it is preferable if the means
is a balloon which surrounds the cannula and which has a surface
with at least one groove-like depression.
[0028] The term "balloon" is here to be understood as any portion
on the cannula shaft having a widened diameter in relation to the
cannula. The "balloon" can be applied on the outside of the cannula
or can be an integral portion of the cannula.
[0029] The expression "groove-like depression" is to be understood
as any change from a regular surface of the balloon making the
balloon surface appear irregular, i.e. ribbed, notched, etc. In
known balloon catheters, the surfaces of the balloon lie smoothly
on the surface of the vessel wall, as a result of which the vessel
is completely closed and a blood flow into areas below the
cannulation site is prevented. In the embodiments according to the
invention, the depressions on the surface advantageously allow some
of the blood in the vessel to be guided also into areas situated
downstream the cannulation site.
[0030] The depressions run the entire length of the balloon. Those
areas of the surface lying between the depressions are raised in
relation to the depressions and press against the vessel wall or
the catheter. By means of the depressions in the surface of the
balloon, groove-like hollows are formed through which some of the
blood in the vessel can flow past the cannula into areas situated
below the cannulation site.
[0031] In a preferred embodiment, the surface having at least one
depression faces towards the vessel and/or the cannula.
[0032] In those embodiments in which the depressions are arranged
on that surface of the balloon facing towards the vessel wall, some
of the blood thus flows between vessel wall and balloon into areas
situated below the cannulation site.
[0033] If the depressions are arranged on the balloon surface
facing towards the cannula, some of the blood in the vessel flows
between balloon and cannula past the cannulation site. The balloon
is arranged on the cannula via the raised areas of its surface
likewise facing the cannula. However, the depressions can also be
arranged on both sides of the balloon, i.e. both on the side facing
towards the vessel wall, and also on the side facing towards the
cannula.
[0034] Each of these embodiments ensures that passages remain
between the balloon and the vessel wall, or between balloon and
cannula, or on both sides, through which passages a subsidiary
stream of the blood can continue onwards through the vessel in a
controlled manner to areas below the cannulation site.
[0035] The surface can in this case have at least one depression,
preferably several depressions, and the flow achieved with these
depressions can be controlled via their number and depth. The
depressions can be of any desired shape, for example in the form of
a groove or notch. The depressions can be distributed symmetrically
or asymmetrically on the surface.
[0036] According to another object, the means is at least one
balloon which surrounds the cannula in sections in such a way that
at least two ends of the balloon pointing in the circumferential
direction are located at a circumferential distance from one
another.
[0037] Here, it is particularly preferable if two balloons are
provided which enclose the cannula in sections.
[0038] In this embodiment, the balloon or balloons do not surround
the cannula completely but instead have two ends pointing in the
circumferential direction. These ends lie at a distance from one
another so that, in the dilated state of the balloon, a passage is
formed through which some blood is led past the cannula.
[0039] The distance between the ends of the balloon or balloons, or
their section surrounding the cannula, and their arrangement on the
cannula can be varied in respect of the cannula circumference and
the desired amount of blood to pass through. In the dilated state,
a passage is thus created through which a subsidiary stream of the
blood can flow through and thus reach areas below the cannulation
site.
[0040] In addition, the number of the balloons can also be varied,
in each case with balloon ends situated at a circumferential
distance from one another, the resulting passages being able to be
set at regular or irregular intervals.
[0041] In a preferred embodiment, the balloon of the abovementioned
appliances according to the invention is dilatable.
[0042] The balloon can in this case be dilated with a fluid
delivered via a second lumen which is in fluidic communication with
the inside of the balloon. This lumen can, for example, be guided
in the form of a tube or second cannula along the outside of the
first cannula or inside the latter. A saline solution, for example,
can then be delivered via this tube for the purpose of dilating the
balloon.
[0043] The use of a saline solution has the advantage that, if for
example the balloon is damaged and the contents escape from it, no
immunological reactions are triggered. When using air, for example,
or other solutions, there is a danger that, if these fluids escape
from the balloon into the blood, embolisms or immunological
reactions may be produced and thus cause considerable damage within
the human body. This danger is avoided by using physiological
saline solution.
[0044] In another embodiment, it is preferable if the balloon is
not dilatable. In this case, the balloon can for example be a
portion of the cannula shaft which, in relation to the cannula,
simply has a widened circumference.
[0045] The balloon can include a material such as latex, for
example, or can be made entirely of latex. This material is
sufficiently well known and established in medical technology and
is, for example, a thin-walled latex material measuring 250 .mu.m
in thickness.
[0046] According to another object, the subsidiary stream remaining
in the vessel can be guided first into the cannula and then out of
it via the at least one means.
[0047] Here, it is particularly preferable if the at least one
means is an outlet in the cannula.
[0048] This has the advantage that, in the event of a narrowing of
the vessel for example, all of the blood in the vessel is first
guided into the cannula, but a subsidiary stream of this blood is
guided back out through at least one outlet located in the
cannula.
[0049] In this embodiment too, it is thus at all times guaranteed
that some of the blood can be led off, and at the same time areas
below the cannulation site are supplied in a defined way with blood
and oxygen.
[0050] Here, it is preferable if the outlet is an opening in the
cannula.
[0051] Such openings can be circular, for example, and are chosen
such that a sufficient amount of blood can be guided out of the
vessel and a certain amount of blood can also be led back out of
the cannula and into the vessel.
[0052] The shape and size of the openings can vary according to the
application, depending on how much blood is intended to reach the
areas situated downstream the cannulation site. In addition, a
plurality of openings can also be provided from which blood can
emerge again from the cannula. In this way, it is possible to
control exactly how much blood is removed from the vessel and how
much blood is to be guided back into the vessel.
[0053] Moreover, according to another object it is preferable if
the outlet is a tubular portion arranged on the cannula, which
tubular portion is guided in the vessel.
[0054] In this embodiment, the tubular portion forks off from the
cannula like a branch. In this embodiment too, it is possible, for
example in the case of a narrowing of the vessel (which would
normally prevent flow of blood to areas situated below the
cannulation point), to deliberately divide the blood in a
controlled manner into subsidiary streams. All of the blood flows
first into the cannula, after which a subsidiary stream of the
blood is then guided out of the vessel and another subsidiary
stream is led back into the vessel via the tubular portion.
[0055] In this embodiment, which represents a kind of "cannula
within a cannula", it is possible, depending on the application, to
vary the length of the tubular portion, its diameter, and the angle
at which it branches off from the cannula. The number of the
tubular portions can also be varied.
[0056] According to still a further object, it is preferable if the
outlet is a cannula-like portion on the appliance, which portion is
guided at least partially outside the vessel.
[0057] In this embodiment, most of the blood in the vessel thus
flows into the cannula and is led out from the vessel. A subsidiary
stream of the blood can then be guided back to the cannulated
vessel through a cannula-like portion lying at least partially
outside the vessel.
[0058] "Cannula-like portion" in this context means an arrangement
which has similar properties to a cannula or a catheter for
example, i.e. can be introduced at least partially into a vessel
and has a lumen. This cannula-like portion can, for example, be
connected t the cannula at one end via an attachment piece. The
attachment piece lies outside the vessel, so that at least that
part of the cannula-like portion connected to the attachment piece
is situated outside the vessel. The other end of the cannula-like
portion can be introduced into the cannulated vessel, as a result
of which a subsidiary stream of the blood can be guided back into
the vessel.
[0059] In a refinement of the embodiments in which the subsidiary
stream remaining in the vessel is first guided into the cannula and
then guided back out of it via the at least one means, it is
preferable if a balloon is additionally provided which is arranged
on the cannula between the point of entry of the blood into the
cannula and the outlet.
[0060] This embodiment has the advantage that the vessel can be
closed by the balloon in such a way that all the blood conveyed in
the vessel is led into the cannula, after which controlled
subsidiary streams are again produced via said means. The balloon
also has the advantage that the appliance can be fixed in position
in the vessel, as a result of which slipping of the appliance is
avoided.
[0061] The balloon can in this case again be dilatable, for example
by means of a fluid delivered via a lumen in contact with the
balloon, or it can be a portion on the cannula having a widened
diameter in relation to the cannula.
[0062] In a refinement of the illustrative embodiments set out
above, it is preferable if means are additionally provided for
measuring at least one of the subsidiary streams.
[0063] In the prior art it is known to use probes, for example, to
measure the oxygen saturation in the areas below the cannulation
sites. However, this measurement simply indicates whether the
measured area is being supplied with fresh blood. This supply can
be achieved locally via a collateral circulation, however, so that
with these appliances it is not possible to measure whether a
specific flow of blood is actually present in the cannulated vessel
and whether the oxygen supply to all the areas below is thus
guaranteed.
[0064] In a further embodiment, it is preferable if means are
additionally provided for regulating the subsidiary streams.
[0065] The advantage of this is that, for example after the
subsidiary stream have been measured by means provided for this
purpose, these subsidiary streams can, if appropriate, be
regulated. Thus, it is possible, on the one hand, to determine
exactly how much blood is removed from the vessel and/or how much
blood remains in the vessel. On the other hand, if necessary, the
individual subsidiary streams can then be increased or reduced, for
example, via regulating means.
[0066] For example, in the embodiment in which a cannula-like
portion is connected via an attachment piece to the cannula outside
the vessel, and in which the cannula alternately has a balloon, a
measurement cell which measures the two subsidiary streams can be
arranged, for example, on the attachment piece. If the subsidiary
stream returned via the cannula-like portion into the vessel is
below a certain level, as a result of which an adequate supply of
oxygen would no longer be guaranteed, this state is detected. If
appropriate, the distribution of the subsidiary streams can then be
regulated by regulating means, so that less blood is removed from
the vessel and thus more blood is conveyed back to the vessel.
[0067] In the other embodiments, the additional measurement device
can be realized in a similar way. Thus, for example, it is possible
to measure the subsidiary stream of blood in the areas below the
cannulation site. It is then possible to determine to what extent
it is necessary to regulate the two subsidiary streams. If a
reduced subsidiary stream is measured in the cannulated vessel,
this subsidiary stream can be increased for example via regulating
means, for example by reducing the dilation of a balloon.
[0068] Moreover, it is generally preferable if the cannula has an
external diameter of ca. 5 to 30 French, in particular of 13 to 21
French.
[0069] In one use, the external diameter of the cannula is chosen
for example with regard to the vessel being cannulated. Determining
the size of the cannula for each individual patient is important,
because the sizes of the vessels vary greatly from patient to
patient. Before the vessels are punctured, their diameter can be
determined by ultrasound for example. Thus, the cannula size can be
chosen optimally, for example, for the femoral artery as the
critical vessel. Moreover, the diameter is determined taking into
consideration the flow rate intended to be conveyed into the
cannula.
[0070] Thus, in the femoral vessels, the maximum depth of insertion
of the cannula is ca. 140 mm and the cannula length is for example
270 mm to 340 mm, depending on whether an introducer is used or
not.
[0071] In the use of dilatable balloons too, their optimal
circumference is be taken into consideration and must be determined
according to the application. Thus, the balloon in the dilated
state can have an external diameter of for example ca. 1 to 8 cm,
in particular of 2 to 5 cm.
[0072] Here too, a different balloon size must be chosen depending
on the size of the vessel intended for cannulation, and in each
case the size should be sufficient to ensure that, in the dilated
state, the side of the balloon facing the vessel presses firmly
against the vessel wall, so that all of the blood is conveyed into
the cannula.
[0073] It is further preferable if the appliance is coated with a
biocompatible material.
[0074] Such a material is chosen to reduce, if not completely
prevent, the risk of blood clotting and inflammatory reactions
which are triggered when vessels and blood come into contact with
foreign material. The appliance can be coated, for example, with
the Bioline-Coating.RTM. sold by Jostra Medizintechnik, Hirrlingen,
Germany. This coating is sufficiently known in the prior art and
has been used successfully in medicine.
[0075] The invention as a further object relates to a method for
cannulation of a blood vessel, in which method the appliance
according to the invention is used.
[0076] The invention as another object further relates to a method
for extracorporeal lung assist with a lung assist device, in which
method the appliance according to the invention is used.
[0077] The term "lung assist device" is to be understood here as
any device with which a gas exchange is possible, i.e. with which,
for example, oxygen can be enriched and CO.sub.2 removed, for
example an oxygenator.
[0078] In this method, the femoral artery, for example, is
cannulated with the appliance according to the invention, as a
result of which it is possible to convey some of the blood into a
lung assist device and also some of it into the areas below the
cannulation site. Some of the blood is then conveyed via a tube to
the lung assist device, for example to an oxygenator, is enriched
with oxygen there and has CO.sub.2 removed, and is delivered, for
example to the femoral vein, via a further tube and a further
cannula.
[0079] The appliance according to the invention is also
particularly advantageous in pumpless arterio-venous lung assist.
In this method, blood trauma can be minimized by omission of a
blood pump and by means of a very short connection and low filling
volumes. Moreover, this pumpless lung assist has the advantage that
no additional machines are needed for maintaining the circulation.
When appropriate cannulas are used, the patient's mean arterial
pressure ensures a sufficient throughflow, the blood in the lung
assist device being saturated with oxygen and having the carbon
dioxide in it washed out. An important condition here is that the
action of the heart is sufficient and only the pulmonary function
is impaired.
[0080] The invention additionally relates to the use of the novel
appliance for cannulation of a blood vessel.
[0081] The invention further relates to the use of the appliance
according to the invention in extracorporeal lung assist using a
lung assist device.
[0082] In this application, the appliance can be used for
extracorporeal lung assist in combination with a pumpless lung
assist device, for example. A lung assist device in the form of a
membrane oxygenator is commercially available, for example, from
the applicant, Nova Lung GmbH, Hechingen, Germany. The special
feature of this heparin-coated lung assist device lies in its very
low resistance with respect to a specific blood flow, for which
very reason it is possible to position it between the femoral
artery and the femoral vein. With the novel appliance it is also
possible to guarantee the supply of blood to areas situated below
the cannulation site.
[0083] It will be appreciated that the features mentioned above and
those still to be explained below can be used not only in the
respectively cited combination, but also in other combinations or
in isolation, without departing from the scope of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0084] Embodiments of the invention are shown in the drawing and
are explained in more detail in the description below. In the
drawing:
[0085] FIG. 1 shows a diagrammatic representation of the
configuration of an extracorporeal lung assist on a patient;
[0086] FIG. 2a shows a diagrammatic representation of an embodiment
of the appliance according to the invention;
[0087] FIG. 2b shows a diagrammatic cross section through the
embodiment from FIG. 2a;
[0088] FIG. 2c shows a diagrammatic cross section through a further
embodiment;
[0089] FIG. 3 shows a diagrammatic representation of a further
embodiment;
[0090] FIG. 4 shows a diagrammatic representation of a further
embodiment of the appliance according to the invention;
[0091] FIG. 5 shows a diagrammatic representation of a further
embodiment.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0092] In FIG. 1, reference number 10 designates a patient whose
femoral artery is designated by 11 and whose femoral vein is
designated by 12. Blood is removed from the femoral artery 11 via a
cannula 14. A tube 15 leads from the cannula 14 to a lung assist
device 16, and a further tube 17 leads from the lung assist device
16 to a further cannula 18 in the femoral vein 12.
[0093] FIG. 1 shows the system of extracorporeal lung assist using
a femoral connection technique. Alternatively, a connection is also
possible, for example, to the jugular vein via the femoral artery
11. The cannula 14 is chosen with a diameter optimally adapted to
the femoral artery 11 of the patient 10 and is introduced into the
femoral artery 11 as critical vessel. The patient's mean arterial
pressure ensures that the blood is conveyed from the femoral artery
11 via the tube 15 to the lung assist device 16. A suitable lung
assist device in the form of a membrane oxygenator is obtainable,
for example, from the applicant, Nova Lung GmbH, Hechingen. By
means of this lung assist device 16, the blood is enriched with
oxygen and at the same time carbon dioxide is removed. The
oxygen-enriched blood leaves the lung assist device 16 via the tube
17 and is delivered to the femoral vein 12 via the cannula 18.
[0094] At the point of entry of the cannula 14 into the femoral
artery, some of the blood, in one use of the appliance according to
the invention, can be routed past the cannula 14, or through it
back into the femoral artery 11, for which reason the blood can
also reach the whole of the lower leg. This circulation ensures
that, in the event of weak or even absent pulmonary function,
oxygen supply to all areas of the body is guaranteed.
[0095] Because of the short line length of the system, measured
from cannula tip to cannula tip, there is no need to insert a heat
exchanger into this lung assist. All the components can
additionally be biocompatible (for example, coated with
Bioline-Coating.RTM.). The cannulas used are ones which are fitted
percurtaneously by the Seldinger technique (for example Nova Lung
BE-AVC 17-01). The venous return likewise takes place via an
arterial cannula since, because of its short length, it has a lower
flow resistance compared to a comparable venous Seldinger
cannula.
[0096] The extracorporeal lung assist can be conducted for several
days to weeks (in extreme cases even for 20 to 29 days, for
example).
[0097] Embodiments of the appliance according to the invention are
shown diagrammatically in FIGS. 2a, 2b and 2c. In these figures,
similar elements are designated by the same reference numbers.
[0098] In the diagrammatic representation in FIG. 2a and in the
cross-sectional representation in FIG. 2b, the appliance as a whole
is designated by reference number 20. This appliance has a cannula
22 with a lumen 23 and with a balloon 24 surrounding the cannula
22. The balloon 24 in turn has passages 26 in the form of
groove-like depressions which run parallel to the cannula surface
or vessel and extend the full length of the surface of the balloon
in the direction of the flow of blood. By means of the passages 26,
raised areas 28 are formed which, as is shown in FIG. 2b, directly
adjoin the wall of a vessel 30.
[0099] The number of the passages 26 on the balloon 24 can be
varied as necessary, as can the depth or shape of the passages.
[0100] After introduction of the cannula 22 into a vessel 30, the
balloon 24 can be dilated by means of a fluid, for example with a
physiological saline solution. In the dilated state of the balloon
24, its raised areas 28 press against the wall of the vessel 30. In
this way, some of the blood is forced into the lumen 23 of the
cannula 22 and there forms a subsidiary stream which leaves the
vessel 30 via the cannula 22. However, some of the blood can also
flow past the cannula 22 via the passages 26, as a result of which
a subsidiary stream is formed which continues flowing through the
vessel 30, as is indicated for example by the arrow 32.
[0101] By means of the passages 26, it is therefore possible for a
large part of the blood to be conveyed into the lumen 23 of the
cannula 22 and outwards from the cannula 22 and, at the same time,
for some of the blood to flow past the cannula 22 via the passages
26. The blood guided through the lumen 23 can be delivered to the
extracorporeal blood circuit. Blood which flows past the cannula 22
via the passages 26 can reach areas below the cannulation site and
can supply these areas with oxygen.
[0102] In another possible embodiment, the passages 26 on the
surface of the balloon 24 can also be formed, for example, on the
side facing towards the cannula 22, as passages 26'. The balloon 24
is in this case arranged on the cannula 22, for example by adhesive
bonding, via the raised areas 28' which then likewise face towards
the cannula 22. The surface of the balloon 24 facing the wall of
the vessel 30 is then smooth and fully contiguous with the wall of
the vessel 30.
[0103] It is of course also conceivable for both surfaces of the
balloon 24, i.e. the surface facing towards the wall of the vessel
30 and also the surface facing towards the cannula 22, to have
passages 26, 26' in the form of depressions.
[0104] Instead of a balloon with a "grooved" surface, it is also
possible, for example, to provide one or more balloons which each
surround the cannula in sections and whose ends are situated at a
defined circumferential distance from one another. The cross
section of such an embodiment is shown in FIG. 2c. In the appliance
20, two balloons 34 and 35 are arranged on the cannula 22. The ends
of the balloons 34, 35 are at a distance from one another such that
passages 36 and 37 are formed. Some of the blood can therefore be
guided past the cannula 22 via these passages 36, 37. The distance
between the ends of the balloons 34 and 35, and the arrangement of
the balloons 34, 35 on the cannula, can be varied depending on the
desired amount of blood that is to flow through. Thus, for example,
the balloons 34, 35 can also be arranged offset on the shaft of the
cannula 22.
[0105] If the balloons are dilatable, they can be dilated either
via a common lumen or each via separate lumens.
[0106] In FIG. 3, an embodiment of the appliance according to the
invention is indicated overall by reference number 40. The
appliance 40 has a cannula 42 and also, in the cannula 42, a
passage 44 in the form of a lateral outlet opening. The appliance
40 according to the invention is fitted in a vessel 46.
[0107] The cannula 42 is inserted with its distal end into the
vessel 46, as a result of which most of the blood flows into the
cannula. A subsidiary stream of the blood, shown by the arrow 48,
leaves the vessel 46 through the cannula 42, and a subsidiary
stream, shown by the arrow 50, flows through the passage 44 out of
the cannula 42 and back into the vessel 46 and continues flowing
through the latter. In this way, even if a vessel constriction were
produced in the area of the cannula 42 during cannulation and the
entire blood stream were forced into the cannula 42, it is possible
to ensure that a defined subsidiary stream 50 can always leave the
cannula and flow back into the vessel 46. Reference number 52
designates an attachment piece via which further arrangements and
means can be fitted on the appliance, for example tubes, further
cannulas, measurement cells, etc.
[0108] The broken lines in FIG. 3 also indicate another embodiment
in which, instead of an outlet opening, at least one passage is
formed through a tubular portion 54. As in the embodiment with the
outlet opening, some of the blood can be guided back out of the
cannula via this portion 54.
[0109] A similar but extended embodiment is shown in FIG. 4, where
the same elements are designated by the same reference numbers as
in FIG. 3.
[0110] In addition to having the cannula 42 and the passage 44, the
appliance 40 also has a balloon 56 which can be dilated by a fluid,
for example via a lumen in the form of a thin tube guided parallel
to the cannula 42. The fluid is preferably a physiological saline
solution. The dilated balloon 56 presses against a vessel wall 57
via its side facing said vessel wall 57 and thus blocks the flow of
blood to the areas situated below the cannulation site. In this
way, all of the blood flows into the cannula 42, as is indicated by
an arrow 58. The subsidiary stream 48 of the blood leaves the
vessel 46 via the cannula 42, and the subsidiary stream 50 emerges
from the passage 44 and continues through the vessel 46.
[0111] In this embodiment, the balloon thus functions as a kind of
"spacer" keeping the cannula from the vessel wall. At the same
time, the cannula 42 can be fixed in position in the vessel 46 by
the dilated balloon 56.
[0112] In this way, as in the embodiment shown in FIG. 2, it is
ensured that the subsidiary stream 48 of the blood in the vessel 46
can be delivered through the cannula 42 to the extracorporeal
circuit, and the subsidiary stream 50 of the blood is returned into
the vessel 46. With reference to FIG. 1, when using the appliance
40 according to the invention, some of the blood removed via the
cannula 42 is delivered through the tube 15 to the lung assist
device 16, is enriched with oxygen in the latter, and is guided
back into the femoral vein via the tube 17 and the cannula 18. The
other subsidiary stream 50 of blood leaves the cannula 42 via the
passage 44 and thus supplies the areas below the cannulation site
with blood and, consequently, oxygen.
[0113] The passage 44 can be varied in shape, size and number
depending on the desired amount of blood that is to flow
through.
[0114] FIG. 5 shows a diagrammatic representation of a further
embodiment of the appliance according to the invention.
[0115] In FIG. 5, the appliance as a whole is designated by
reference number 60. This appliance, lying in a vessel 61, has a
cannula 62 with a balloon 64.
[0116] In the dilated state, the surface of the balloon 64 facing a
vessel wall 65 presses against said vessel wall 65 and in this way
forces the blood into the lumen of the cannula 62.
[0117] The blood is conveyed through a portion of the cannula 62 to
an attachment piece 66 on which a cannula-like portion 68 is also
arranged. A subsidiary stream can be conveyed through this
cannula-like portion 68 back into the vessel 61 and thus supply the
areas below the cannulation site with blood, as is indicated by an
arrow 70. The arrow 72 indicates a subsidiary stream which leaves
the vessel via the cannula 6.2 and the attachment piece 66. The
subsidiary stream 72, which for example is delivered to a lung
assist device in an extracorporeal lung assist, is preferably
greater than the subsidiary stream remaining in the vessel.
[0118] In the embodiment shown in FIG. 5, a measurement cell 74 is
also arranged on the attachment piece 66, with which measurement
cell 74 the subsidiary streams 70 and 72 can be measured. For
example, if the subsidiary stream which remains in the vessel via
the cannula-like portion is disadvantageously reduced, as a result
of which the supply of oxygen to the areas below the cannulation
site is no longer guaranteed, this can be measured by the
measurement cell 74 and can, if appropriate, be regulated. The
attachment piece can, for example, include polyvinyl chloride, or
it can be made entirely of this material.
[0119] The subsidiary stream flowing into the areas situated below
the cannulation site can be regulated, for example, by increasing
the subsidiary stream conveyed back into the vessel 61 via the
cannula-like portion 68 and/or by "venting" the balloon 64 so that
not all of the blood is guided into the cannula 62. Moreover, in
the event of a signal indicating an inadequate supply to the lower
areas, the arrangement as a whole can be removed.
[0120] In the various embodiments, the balloon is in each case
arranged on the cannula by adhesive bonding. After the appliance
has been introduced into a vessel, the balloon can be dilated using
a fluid, for example a physiological saline solution. The fluid is
in each case delivered via a second lumen which is in fluidic
communication with the balloon. This lumen can extend either as a
tube parallel to the cannula or can be integrated in the latter as
a second lumen.
[0121] In the various embodiments, the appliance as a whole can
also be coated with a biocompatible coating, for example with the
Bioline.RTM. coating developed and sold by Jostra.
[0122] It will be appreciated that further changes and
modifications are conceivable without departing from the scope of
the present invention.
* * * * *