Note: Descriptions are shown in the official language in which they were submitted.
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TISSUE ADHESIVE FOR TREATING VIGOROUSLY BLEEDING SURFACES
BACKGROUND
The present invention relates generally to adhesives, more specifically it
relates to medical
adhesives, and particularly it relates to tissue adhesives which exhibit high
bio-compatibility,
excellent tensile properties, are bio-absorbable, do not interfere with the
healing processes and are
S easily applied to various tissues. The present invention is also
particularly well suited for
controlling complex, vigorous bleeding emanating from large surface areas,
specifically the
visceral organs, lungs and the vascular system.
The use of adhesive compounds in wound sealing and hemorrhage control dates
back to
the sixteenth century. Early sealants consisted of rosewater, turpentine and
eggs and were used in
conjunction with ligatures. Biologic and Synthetic Polymer Networks, Ed. O.
Kramer; Elsevier
Applied Science, New York (1988). While such techniques offered marked
improvement over
cautery, little effort was made to advance the art until the Spanish Civil war
when plasterized
cotton was introduced. Leo Mandelkern, An Introduction to Macromolecules 2nd
ed.; Springer
Verlag, New York (1983). Early cotton-based adhesives were little more than
surgical packings
and could not control large, profusely bleeding visceral surfaces.
Subsequent wars brought new experiments with adhesives to aid in controlling
the
massive, vigorously bleeding hemorrhages associated with battlefield injuries.
In the 1940s,
trauma surgeons began experimenting with fibrin sealants, however, these did
not possess the
strength required to adequately control vigorous bleeding wounds and W.W.II
field hospitals
returned to plasterized cotton. Turner Alfrey et al., Organic Polymers;
Prentice Hall, New Jersey
(1967). Technological advances in polymer chemistry led to the development of
cyanoacrylates
that were first used as tissue adhesives in the Vietnam war. Since that time,
moderate advances
have been made in the development of modern tissue adhesives, but none have
adequately
addressed the technical and biological complexities associated with vigorous
bleeding
ZS homeostasis.
Severe traumatic injuries result in massive intra-abdominal hemorrhages in
approximately
10 to 25% of cases. Uncontrolled bleeding and transfusion-associated
complications make up the
majority of deaths in these patients. The current recommended standard of care
for treating intra-
abdominal bleeding is a process called packing which utilizes pressure and
nylon gauze to contain
the blood flow. A. Sauaia, et al., Epidemiolo~ of Trauma Deaths: a
Reassessment, Journal of
Trauma (February 1995). However, in spite of advances in nearly every other
branch of medicine,
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mortality rates associated with severe abdominal trauma remain high.
Traditional methods of
tissue closure including tapes, sutures and staples are completely inadequate
when the effected
area is the surface of a visceral organ that has been severely lacerated or
ruptured.
Tapes, sutures and staples fail to assure fluid-tight closures and often
require surgical
removal even when used as clinically indicated. These disadvantages are
further exacerbated by
the scarnng, additional tissue damage and inflammation often associated with
such techniques.
The exposed tissue at the suture site can become infected requiring frequent
cleaning and
treatment with topical as well as systemic antibiotics. Another significant
drawback to sutures,
staples and tapes is their inability to be used in combination with
microsurgical techniques.
Consequently, the development of a versatile bio-compatible, non-toxic tissue
adhesive, suitable
for controlling vigorous bleeding over large surface areas, that has high
adhesive strength and
excellent tensile properties would constitute a major medical and technical
advance.
Multiple factors must be considered when evaluating candidate tissue
adhesives. The
most important of these include bio-compatibility, resistance to fracture,
pliability, adhesive
strength, ease of application, and rapid curing time. Materials which possess
ideal bio
compatibility are immunologically inert, do not interfere with wound healing,
do not induce
strictures or scars, are bio-absorbable and completely non-toxic. Due to these
demanding criteria,
it has been extremely difficult to find an ideal material.
Various forms of wound sealant technologies exist including fibrin sealants,
gelatin
resorcin aldehyde adhesives, albumin based tissue adhesives, acrylates, tissue
welding
technologies and argon beam electro-coagulation. In the United States, fibrin,
acrylate and argon
beam electro-coagulation have received the most attention. None of these
technologies
adequately control the complex, vigorous bleeding associated with severe
internal injuries.
Fibrin tissue adhesives have attracted considerable attention due to the high
bio-
compatibility associated with fibrin monomers. Fibrin tissue adhesives are
administered as two
components and work by forming an artificial fibrin clot over the effected
area. The fibrinogen
and Factor XIII component is delivered to the wound site followed by a
thrombin and calcium ion
solution which initiates the conversion of fibrinogen into fibrin monomers.
Fibrin tissue adhesives
exhibit relatively weak tissue binding properties, have a fairly long set-up
time and are not suitable
for use in treating large, aggressively bleeding surfaces. The amount of
fibrin required to produce
a satisfactory adhesive requires multiple blood donors which increases the
risk of transmitting
blood borne diseases. These risks will be significantly reduced as recombinant
coagulation factors
and fibrin become more readily available.
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Fibrin based tissue adhesives have been described in a number of U. S.
patents, the most
relevant of those include 4,414,976, 4,909,251, 5,219,328, 5,395,923,
5,407,671, 5,464,471,
5,804,428 and 5,814,022. Patent number 4,414,976 describes the basic fibrin
based tissue sealant
and discloses the fundamental theory associated with its biological activity.
The remaining
patents cited above are primarily directed at novel means for delivering
fibrin and the required
clotting agents to the wound site in a convenient fashion making the use of
this tissue adhesive
more acceptable to physicians. Patent number 5,407,671 addresses the
transmission of blood
borne pathogens and is directed at minimizing this inherent risk, while patent
5,464,471 is
directed to recombinant forms of fibrin and application techniques thereof.
However, none of
these patents discuss the use of a fibrin based tissue adhesive for
controlling vigorous bleeding
tissues.
Gelatin Resorcin Aldehyde Tissue Adhesives (GRATA) are currently available in
Germany
for use in conjunction with cardiovascular surgery. These compounds are
generally used as
reinforcement or leathering agents on fragile tissues. Gelatin Resorcin
Aldehyde Tissue
Adhesives are composed of heated gelatin that is mixed in situ with a cross-
linking agent such as
glutaraldehyde or formaldehyde. In general, GRATAs are relatively easy to
apply and have
moderately good adhesive qualities. However, GRATA do not possess adhesive
qualities
sufficient to seal large areas of vigorously bleeding tissues and there are
reports of post surgical
inflammation in rabbits indicating problems with bio-compatibility. U.S.
patent number 5,292,333
describes a more recent GRATA development but does not suggest that the
claimed tissue
adhesive would be suitable for sealing large surface areas of vigorously
bleeding tissues. The
examples described therein are limited to vascular grafts.
United States Patent number 5,583,114 discloses an albumin based tissue
adhesive
prepared using an alkaline solution of human serum albumin that is cross-
linked with polyethylene
ZS glycol. The resulting tissue adhesive is intended for use as an adjunct or
replacement of sutures,
stables, tapes and/or bandages. Other proposed uses include post-surgical
applications to reduce
tissue adhesions, sealing tissues to prevent or control blood or other fluid
leaks at suture or staple
sites and for controlling leaks in the pulmonary system. Treating large
surface areas of vigorously
bleeding tissues is not described.
Acrylates are semi-crystalline compounds that tend to fracture under stress
which can
result in wound healing inhibition. The cyanoacrylates have been exhaustively
studied and is the
most successfizl acrylate class used as tissue adhesives. N-isobutyl and N-
butylcyanoacrylate
were initially selected for development after animal tests suggested that
these compounds
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demonstrated superior tissue adhesiveness and minimal tissue inflammation. N-
butylcyanoacrylate is available outside the U.S. for human applications and as
an approved
veterinary compound within the U.S.
Acrylate tissue adhesives require a dry field for application, fragment
easily, are non-bio-
absorbable and the polymerization can be extremely exothermic. It has also
been reported that
the ridged acrylate polymer is nonporous and prevents cell communication and
movement which
significantly retards would healing. This combination of adverse physical
qualities has
significantly limited the use of acrylate tissue adhesives with internal
applications. Several U.S.
patents have been granted in this area of tissue adhesive research including
3,483,870, 3,995,641,
and 5,350,798. The compounds described in these patents are primarily intended
for sealing
superficial cuts and wounds and not intended to control the vigorous bleeding
associated with
massive injuries to vital organs.
Tissue welding is an area where significant research and development has been
focused.
Numerous U.S. patents have been issued in this area including four assigned to
Fusion Medical
Technologies, Inc. of Mountain View, CA. Patent 5,669,934 describes the use of
a preformed
sheet made of collagen, gelatin and mixtures thereof combined with a
plastisizer which is sealed to
the injured tissue using radio frequencies between 20 and 120 watts. The
principle application for
this device is the repair of severed and torn tissues including blood vessels,
ducts, muscle, fascia,
tendon and bone. Although bleeding is often a collateral consequence of
injuries to these tissues,
control of vigorous bleeding over large surface areas is not disclosed in the
'934 patent.
Fusion Technologies patents 5,690,675, 5,749,895 and 5,824,015 also use
patches made
from collagen and/or gelatin which are used in conjunction with a device which
emits sufficient
radio frequency or optical energy to literally weld the patch into place.
These devises are
particularly well suited for repairing severed tissues, veins, nerves, tendons
and muscle where
strong, rapid structural repair is required. However, this process does not
lend itself to sealing
large vigorously bleeding surfaces and such use is not described in the above
cited patents.
A hybrid technology has been developed and is disclosed in U.S. patent numbers
5,209,776 and 5,292,362 (Bass patents). These patents describe the development
of a tissue
adhesive that is principally intended to be used in conjunction with a laser
to weld severed tissues
and/or prosthetic material together or to form a water tight seal for tissues
or prosthetic devices.
However, in some cases the tissue adhesive described will spontaneously weld
tissues together
without the use of an external energy source. The Bass patents disclose an
adhesive comprising a
first component of fibrous and/or globular proteins, preferably collagen and
albumin, which can be
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used either together or separately and combined with a second component that
is made of
proteoglycans, glycoproteins, saccharides, polyalcohols, proteins, gels, or
similar compounds.
The second component provides a matrix, or foundation, for the first component
to complex with
and form a gel or solution. The resulting gel or solution can be subsequently
modified with
viscosity agents, bonding enhances and polar dyes which alter the tissue
bonding effects when
used in conjunction with a laser.
In the Bass patents neither the collagen nor the albumin are ultrasonically
modified and the
use of both proteins is not required. In the present invention the albumin and
collagen are
ultrasonically treated and are used together in a synergistic fashion.
Furthermore, there is no
chemical cross-linking of the proteins used in the Bass patents. Equally
important is that neither
Bass patent discloses the use of the adhesive system described for controlling
large surface areas
of complex, vigorously bleeding tissues.
Argon beam high electro-coagulation is a physical technique, not a tissue
adhesive per se.
High frequency energy is applied directly to the tissue surface causing the
rapid evaporation of
water resulting in coagulation. However, this process has not proven
successful in treating large
tissue surface areas and is especially ineffective in patients with
coagulopathies.
A number of interesting approached to wound and tissue sealing are described
in U. S.
patents 4,804,691, 5,445,597, 5,571,080, 5,788,662, and 5,830,700. These
include recombinant
hybrid proteins, fibrin/thrombin dispensing devises, adhesive pads, and novel
polyester
compounds. However, none of these devices adequately address the need for a
tissue adhesive
suitable for emergency use involving traumatic injuries resulting in large
surfaces of complex,
vigorously bleeding tissues.
The preceding review of the prior art demonstrates the dearth of technical
advances in
controlling severe bleeding situations using bio-compatible adhesives. In the
four centuries since
crude sealants consisting of rosewater, turpentine and eggs were first
introduced the only
significant advance has been Trueta's development of plasterized cotton over
100 years ago. The
present invention offers the first acceptable alternative to crude packing
techniques currently
practiced in trauma centers throughout the world and represents a novel,
technically significant
and life savings advance in the medial sciences.
It is therefore the object of the present invention to produce a tissues
adhesive that is bio-
compatible, bio-absorbable, does not interfere with tissue healing, has
sufficient adhesive strength
to control vigorous bleeding over large surface areas, can be applied rapidly
to a variety of tissues
and is suitable for use in patients with coagulation disorders.
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SUMMARY
The present invention is directed to a composite tissue bonding and tissue
modifying
technology which fulfills the needs expressed above. This novel tissue
adhesive technology
comprises a combination of ultrasonically treated proteins including collagen
and albumin which
form a viscous material that develops adhesive properties when chemically
cross-linked.
A novel new cross-linking agent with surprisingly stable properties was
developed in
association with the tissue adhesive described and claimed herein and is
considered to be within
the scope of the present invention. This new cross-linking agent is a product
of reacting
glutaraldehyde with amino acids or peptides and allowing the reaction to
proceed to completion.
This chemical cross-linker is mixed with the ultrasonically treated proteins,
allowed to react for a
pre-determined time, then used to seal the large surface areas of vigorously
bleeding tissues
including, but not limited to, the liver, lungs and major vascular systems in
patients with and
without bleeding disorders. This same tissue adhesive has proven to work well
in sealing suture
sites to prevent leakage.
Another surprising and exciting aspect of this invention is the versatility of
the base
adhesive. When the cross-linked tissue adhesive of the present invention is
mixed with
magnesium carbonate under alkaline conditions the resulting compound becomes a
powerful bone
adhesive. This bone adhesive differs from the tissue adhesive in that it is
much less malleable
upon curing making it ideal for cementing rigid anatomical structures while
maintaining the bio-
absorbability and high bio-compatibility properties of the base adhesive.
The novel combination of cross-linked fibrous and globular proteins were
specifically
selected with bio-compatibility in mind. Collagen and albumin are both
ubiquitous mammalian
proteins that have a long history of medical use with few reported side
effects. In studies detailed
below, postmortem examinations up to six months following surgery demonstrated
normal
healing, no inflammation and uncomplicated resorbtion which is indicative of
high the bio-
compatibility characteristic of this novel tissue adhesive.
The tissue bonding materials described in this patent include novel semi-
liquid tissue
adhesives, non-malleable bone adhesive, surprisingly stable and effective
cross-linking agents and
combinations thereof. These and other features, aspects and advantages of the
present invention
will become better understood with reference to the following description and
appended claims.
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DETAILED DESCRIPTION
Tissue adhesives formed by the methods of the present invention must possess
the
adhesive strength necessary to seal a vigorous bleeding tissue sufficiently to
allow complete
healing with minimal toxic side effects. Tissue adhesives of the present
invention which develop a
cohesive strength of at least 5 kg/cm2 at five minutes post application with
an adhesive bonding
strength of at least 1 kg/cmz can adequately control vigorous bleeding in all
body tissues including
spleens, livers, lungs, the vascular system and bone.
One embodiment of the present invention is prepared by mixing an
ultrasonically treated
fibrous protein with ultrasonically treated globular protein, adding a cross-
linking agent and
allowing the reaction to proceed for 1-3 minutes. The resulting adhesive can
then be applied
directly to vigorously bleeding tissues including visceral organs.
In the preferred embodiment of the present invention the novel cross-linking
agent is first
prepared by mixing three parts glutamate solution (3-6 M in distilled water)
with one part of a 7%
aqueous glutaraldehyde solution. The resulting mixture is allowed to react for
48 hours at room
temperature or until no discernible aldehyde signal is detectable using
infrared spectroscopy, the
solution has turned yellow-brown, pH is approximately 4.5-6.5 and all trace of
characteristic
aldehyde odor is eliminated. When the fully reacted cross-linking agent is
further examined using
infrared analysis of aqueous and methanol solutions, a lower range infrared
absorption signal is
detected which is consistent with an incomplete pyrimidine compound. The
importance of this
signal in not known and is not intended to limit this invention.
A one percent collagen solution, preferably bovine or porcine collagen, is
made in distilled
water and sonicated at 0.5 to 1.5 watts/cm2 at 17 kHz to 24 kHz for
approximately 12 hours at
6°C to 10°C. The sonicated solution is then concentrated using
cold lyophilization. The final
concentration of the collagen solution is between 35% to 45%. A five percent
aqueous solution
of albumin, preferably human, is processed as the collagen was except that the
total sonication
time is reduced to approximately two hours. The albumin was then concentrated
to 35- 45%
using cold lyophilization. The resulting collagen and albumin solutions are
then mixed in a l:l
ratio.
The final adhesive is prepared by mixing four to eight parts of the
collagen/albumin
solution with one part of the cross-linking solution and 0.01% methylene blue.
This adhesive can
used as a stand alone sealant or in conjunction with tissue patches made from
bio-compatible
materials.
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In yet another embodiment, 0. S M magnesium carbonate diluted in an 0.5 M
aqueous
solution of ammonium hydroxide, pH 8, is added to the preferred embodiment of
the tissue
adhesive in an amount sufficient to give a viscosity suitable for use as a
bone adhesive. In another
version of this bone adhesive, approximately 9% to 20% by weight of
hydroxyapatite was added
to in addition to the alkaline magnesium carbonate. Both formulations were
equally satisfactory.
Experiments were conducted in vivo using porcine and rabbit models. Test
animals were
anti-coagulated with intravenous heparin (300 unit/kg) and measured bleeding
times (PTT)
exceeded 250 seconds. A pig's liver is severely lacerated and the surface
disrupted using multiple
strokes with a scalpel. This heavily bleeding, flat disrupted surface
represents the worst-case
scenario for a wound closure agent. The surface of the liver is coated with
the tissue adhesive to
a thickness of approximately one to three millimeters, and after a short
application time, the
bleeding is completely stopped. Postmortem studies of tissues from pigs
sacrificed at six weeks
following the application of the tissue adhesive to vigorously bleeding
visceral organs
demonstrated minimal adhesions, normal wound healing and ongoing resorbtion of
these adhesive
materials. Similar results were achieved with rabbits.
In another experiment the abdominal artery of a 145 pound pig is exposed and
opened
with a 4 mm punch. With no clamping an 12 mm bio-compatible tissue patch
coated with the
tissue adhesive of the present invention is applied and held in place over the
hole. Complete
occlusion and sealing is observed when pressure is released.
Following the aortic punch procedure the same anti-coagulated pig has a
portion of the
lower lobe of a lung surgically removed then re-attached loosely with sutures.
Water is poured
over the suture area to demonstrate that air is still escaping from the repair
site. The present
tissue adhesive is then applied to the site to correct this. The wound was
completely closed, all
bleeding and air leakage was stopped.
To determine whether the present invention would also be suitable for sealing
suture lines,
braided sutures were coated with the tissue adhesive of the present invention
and then used to
suture fresh porcine aorta and pulmonary segments together. A control set
using braided sutures
that were not previously coated with adhesive were also prepared. Next, both
groups of sutured
tissues were pressurized with water to 200 mm Hg and leakage was compared.
Less than 25% of
the pre-treated group demonstrated leakage compared with leakage rates of up
to 30 cc per
minute in 100% of the control group. Ten replicates were used for each group.
Although the present invention has been described in considerable detail with
reference to
certain preferred versions thereof, other versions are possible. For example,
other amino acids
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and concentrations than 3-5 M glutamate can be used in the preparation of the
cross-linking
agent. Many different grades and sources of fibrous protein, globular protein,
glutaraldehyde,
amino acids and polypeptides are acceptable and this adhesive can be used with
or without the
addition of methylene blue. Bio-compatible tissue patches made from a variety
of materials can
be used with the present adhesive, or the adhesive may be used in a stand-
alone capacity.
Therefore, the spirit and scope of the appended claims should not be limited
to the description of
the preferred versions contained herein.
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