U.S. patent application number 11/083004 was filed with the patent office on 2005-10-06 for anti-adhesion spraying.
Invention is credited to Colt, M. Jude, Greenawalt, Keith E., Kablik, J. Jeffrey.
Application Number | 20050220721 11/083004 |
Document ID | / |
Family ID | 34994374 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050220721 |
Kind Code |
A1 |
Kablik, J. Jeffrey ; et
al. |
October 6, 2005 |
Anti-adhesion spraying
Abstract
Dry powders containing bioresorbable hyaluraonic acid ("HA") are
applied directly to a desired location in a patient wound to reduce
adhesions, without first forming a hydrated gel. HA includes
hyaluronic acid that has been modified, cross-linked or combined
with other substances. It is important to control the size of the
particles in the powder. The powder is essentially dry and blowable
powder. At least 90% of powder particles have a maximum dimension
between 30 .mu.m and 1 mm.
Inventors: |
Kablik, J. Jeffrey;
(Tyngsboro, MA) ; Greenawalt, Keith E.; (Milton,
MA) ; Colt, M. Jude; (Manomet, MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
34994374 |
Appl. No.: |
11/083004 |
Filed: |
March 17, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60554009 |
Mar 17, 2004 |
|
|
|
Current U.S.
Class: |
424/46 |
Current CPC
Class: |
A61K 31/74 20130101;
A61L 31/042 20130101; B05B 7/1486 20130101; B05B 11/062 20130101;
A61P 41/00 20180101; A61L 31/042 20130101; C08L 5/08 20130101; A61M
13/00 20130101; A61M 2202/064 20130101; A61L 31/14 20130101; B05B
7/1422 20130101; A61L 2/0035 20130101 |
Class at
Publication: |
424/046 |
International
Class: |
A61L 009/04; A61K
009/14 |
Claims
What is claimed is:
1. An essentially dry blowable powder comprising bioresorbable HA,
said powder being characterized in that at least 90% of powder
particles have a maximum dimension between 5 .mu.m and 1 mm.
2. The powder of claim 1 in which said powder further comprises
CMC.
3. The powder of claim 1 or claim 2 in which said HA or CMC or both
is modified to reduce solubility or to enhance anti-adhesive
properties of said powder or both.
4. The powder of claim 3 in which said powder comprises the
reaction product of HA or CMC, or both, with a carbodiimide.
5. The powder of claim 3 in which said powder comprises the
reaction product of HA with a divinylsulfone or a diepoxide.
6. The powder of claim 1 in which said powder is characterized in
that at least 90% of the powder particles have a maximum dimension
between 70 .mu.m and 600 .mu.m.
7. A method of reducing undesirable adhesions during wound healing,
comprising applying the powder of claim 1 into a location in a
wound where adhesion reduction is desired, said powder being
applied to be present in a mass per area sufficient to reduce
adhesions as the wound heals.
8. A method of reducing undesirable adhesions in a wound comprising
applying a dry, blowable powder into a location in said wound where
adhesion reduction is desired, said powder being applied to be
present in a mass per area sufficient to reduce said adhesions,
said powder comprising bioresorbable HA, CMC, or both.
9. The method of claim 7 or claim 8 in which said mass/area is
greater than 2 mg/cm.sup.2.
10. The method of claim 7 or claim 8 in which said wound is a
surgical wound.
11. The method of claim 7 or claim 8 in which said powder is
applied directly to an open wound.
12. The method of claim 11 in which said powder is applied to said
wound from a shaker comprising a powder reservoir and orifices
sized to release powder when the shaker is agitated.
13. The method of claim 10 in which said surgical wound is produced
by a laparoscopic procedure on a patient, and said powder is
applied to said wound via a conduit communicating from a first
location outside the patient's body to a second location within the
patient's body for delivery to said location in said wound.
14. The method of claim 13 further comprising, a. delivering a mesh
material to said wound via a laparoscopic device; and b. then
applying said powder to a surface of said mesh via said exit
conduit.
15. The method of claim 7 or claim 8 in which said location is on a
surface of a tissue prosthesis.
16. The method of claim 7 or claim 8 in which said location
includes the edges of said prosthesis.
17. The method of claim 7 or claim 8 comprising a. providing
airflow through a chamber containing said powder to entrain said
powder in said airflow; and b. directing the airflow with entrained
powder to said location.
18. The method of claim 17 in which said airflow is provided by a
hand powered air pump or a squeeze bulb.
19. The method of claim 18 in which said airflow is provided by a
source of pressurized gas in a hospital operating room.
20. The method of claim 7 or claim 8 in which said powder is
provided via a tubular conduit positioned to carry said powder from
said reservoir to said location in said wound.
21. The method of claim 20 in which said conduit includes an
airflow modifier.
22. The method of claim 21 in which said airflow modifier comprises
a swirl inducer positioned in said conduit to impart a radial
component to said airflow.
23. The method of claim 7 or claim 8 comprising irrigating the
location prior to applying the powder.
24. The method of claim 15 comprising saturating said prosthesis
with an aqueous solution prior to introducing the powder.
25. Apparatus for delivering powder to a wound, said apparatus
comprising a powder reservoir connected to an incoming airflow
conduit and an exiting airflow conduit, said conduits being
connected to said reservoir to entrain powder in airflow that
enters through said incoming conduit and exits through said exiting
airflow conduit, said reservoir comprising the powder of claim
1.
26. The apparatus of claim 25 in which said incoming airflow
conduit is connected to a squeeze bulb.
27. The apparatus of claim 26 comprising a handgrip, said squeeze
bulb being positioned within said grip so as to permit the user to
hold the apparatus in one hand and, while holding it, to squeeze
the bulb and deliver power from the exiting airflow conduit.
28. The apparatus of claim 25 in which said incoming airflow
conduit includes a connector for attachment to a hospital operating
room gas supply.
29. The apparatus of claim 25 in which the exit conduit comprises a
swirl inducer adding a radial component to airflow velocity.
30. The apparatus of claim 25 in which the reservoir is removable,
so that after use, the spent reservoir can be replaced with a
reservoir comprising a new powder charge.
31. The apparatus of claim 25 in which at least the exit conduit is
hydrophobic.
32. The apparatus of claim 31 in which the exit conduit is coated
with a hydrophobic material.
33. The apparatus of claim 31 in which the exit conduit is made of
a hydrophobic material.
34. The apparatus of claim 32 or claim 33 in which the hydrophobic
material is a hydrophobic plastic.
35. Apparatus comprising a dry, blowable powder to be introduced
into a location in said wound where adhesion reduction is desired,
said powder comprising HA or CMC, said apparatus further comprising
a reservoir to contain said powder and exit orifices to apply the
powder to said location.
36. A method of making the powder of claim 1 comprising, in any
sequence, providing a solid material comprising HA, milling solid
material comprising HA, and sieving solid material comprising HA to
select material characterized in that at least 90% of powder
particles have a maximum dimension between 5 .mu.m and 1 mm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Under 35 U.S.C. .sctn.119(e)(1), this application claims the
benefit of prior U.S. provisional application 60/554,009, filed
Mar. 17, 2004, which is hereby incorporated by reference in its
entirety. This application also incorporates by reference in its
entirety a U.S. utility patent application, U.S. Ser. No.
11/______, filed Mar. 17, 2005 by J. Jeffrey Kablik, Andrew Gentile
and A. David Boccuti, entitled POWDER DELIVERY DEVICE.
TECHNICAL FIELD
[0002] This invention relates to preventing adhesions, particularly
adhesions that form during healing of surgical wounds.
BACKGROUND
[0003] Undesirable tissue scarring can sometimes connect layers of
adjacent bodily tissue, or tissues and internal organs, which
should not be connected. Such internal scarring, termed adhesions,
may form during the healing that follows surgical procedures,
preventing the normal motions of those tissues and organs with
respect to their neighboring structures.
[0004] Various adhesion prevention compositions have been proposed,
such as hydrated gels of high molecular weight carboxyl-containing
biopolymers forming a physical barrier to separate tissues from
each other during healing so that adhesions between adjacent
structures do not form. Desirably, the barrier is bioresorbable, so
that it is gradually eliminated after it is no longer needed.
SUMMARY
[0005] We have discovered that dry powders containing hyaluronic
acid ("HA") may be applied directly to a desired location in a
patient wound to reduce adhesions. Upon application of the powder,
in the presence of body fluids and liquids, the dry powder will
hydrate to form gel, which acts as an adhesion barrier. HA includes
hyaluronic acid that has been modified, cross-linked or combined
with other substances. It is important to control the size of the
particles in the powder.
[0006] In general, one aspect of the invention features an
essentially dry blowable powder comprising bioresorbable HA. "Dry"
means having a water content low enough to permit effective
entrainment of the particles in a stream of flowing gas, for
example less than 25% water by weight. "Blowable" means having a
size, moisture content and shape to permit effective and
controllable direction of entrained particles in flowing gas. At
least 90% of powder particles have a maximum dimension between 5
.mu.m and 1 mm. In preferred embodiments of this aspect of the
invention, the powder further comprises carboxymethyl cellulose
(CMC), and the HA or CMC or both may be modified to reduce
solubility or to enhance anti-adhesive properties of said powder or
both. The modification can be such that the powder comprises the
reaction product of HA or CMC, or both, with a carbodiimide or a
divinylsulfone. Preferably, at least 90% of the powder particles
have a maximum dimension between 70 .mu.m and 600 .mu.m,
particularly when the powder is to be applied by spraying.
[0007] In another aspect of the invention, a powder comprising
bioresorbable HA, CMC, or both is applied into a location in a
wound where adhesion reduction is desired, in a concentration
sufficient to reduce adhesions as the wound heals. Preferably, at
least 90% of powder particles have a maximum dimension between 5
.mu.m and 1 mm.
[0008] In preferred embodiments of this aspect of the invention,
the powder is applied in a mass per area that is greater than 2
mg/cm.sup.2. Typically the wound is a surgical wound. For example
the powder may be applied through an open incision directly to a
location within a surgical field where adhesions may be a problem.
It may be applied by a sprayer or from a shaker that has a powder
reservoir and orifices sized to release powder when the shaker is
agitated. The invention may also be used to prevent adhesions
during healing of a surgical wound produced by a laparoscopic
procedure on a patient. In that case, the powder is applied to the
wound via a conduit (trocar cannula) communicating from a first
location outside the patient's body to a second location within the
patient's body. The invention thus provides an improved way to coat
a dry mesh tissue prosthesis with an adhesion barrier via a
laparoscopic device. Once the mesh is in place in the wound, the
powder is then applied to a surface of the mesh via the exit
conduit.
[0009] More generally, the above method can be used to coat a
tissue prosthesis (e.g. a mesh) that has already been positioned in
the wound. For example, adhesions that may form around the edge of
the prosthesis are controlled by coating the edges of the
prosthesis in situ. Tacks or stitches in the prosthesis may also be
coated to reduce adhesions at those locations. Alternatively, the
prosthesis may be positioned in the wound without any barrier
layer, and then covered with powder. Preferably the prosthesis is
saturated with an aqueous solution before the powder is
applied.
[0010] According to one aspect of the invention, the powder is
entrained in airflow passing through a chamber containing the
powder. The resulting airflow with entrained powder is directed to
the location. The airflow may be provided by a hand powered air
pump or a squeeze bulb or by a source of pressurized gas in a
hospital operating room. The entrained powder may be provided to
the location via a tubular conduit positioned to carry the powder
from the reservoir to the location in the wound. The conduit may
include an airflow modifier, such as a swirl inducer positioned in
the conduit to impart a radial component to the airflow.
[0011] It is preferable to irrigate the wound location prior to
applying the powder to provide liquid for hydrating the powder into
a gel.
[0012] Another aspect of the invention features apparatus for
delivering powder (such as the above described powder) to a wound.
The apparatus includes a powder reservoir connected to an incoming
airflow conduit and an exiting airflow conduit. The conduits are
connected to the reservoir to entrain powder in airflow that enters
through the incoming conduit and exits through the exiting airflow
conduit. Airflow may be provided by a hand powered air pump or a
squeeze bulb connected to the incoming airflow conduit, and the
pump or squeeze bulb may be positioned within a handgrip to permit
the user to hold the apparatus in one hand and, while holding it,
to squeeze the pump or bulb and deliver powder from the exiting
airflow conduit. Alternatively, the incoming airflow conduit
includes a connector for attachment to a hospital operating room
gas supply. The exit conduit may include a swirl inducer adding a
radial component to airflow velocity. The apparatus may also
include a valve positioned upstream of the reservoir to prevent
backflow from the reservoir. The reservoir may be removable, so
that after use, the spent reservoir can be replaced with a
reservoir comprising a new powder charge. Preferably at least the
exit conduit is hydrophobic to prevent fluid accumulation, e.g., it
is coated with a hydrophobic material or made of a hydrophobic
material such as hydrophobic plastic.
[0013] In one embodiment the powder is HA or CMC, or both.
[0014] Still another aspect of the invention features a method of
making the powder described above by providing a solid material
comprising HA, milling solid material comprising HA, and sieving
solid material comprising HA to select material characterized in
that at least 90% of powder particles have a maximum dimension
between 5 .mu.m and 1 mm.
[0015] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is a side view of one embodiment of a hand-held
pistol-grip sprayer for delivering anti-adhesion powder.
[0017] FIG. 2 is a side view of a second embodiment of a sprayer
for delivering anti-adhesion powder, using a pressurized canister
with a spray valve.
[0018] FIG. 3 is a diagrammatic view, partially in section, showing
entrainment of powder particles.
[0019] FIG. 4 is a view of another embodiment of a hand-held
pistol-grip sprayer.
[0020] FIG. 5 is a view of another embodiment of a bulb
sprayer.
[0021] FIG. 6 is a diagrammatic view, partially in section, of a
sprayer using a source of pressurized gas.
[0022] FIG. 7 is a diagrammatic view, partially in section, of
another embodiment of a bulb sprayer.
[0023] FIG. 8 is a process flow diagram for a method of making
powder.
[0024] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0025] Powder Formulation
[0026] The invention features hyaluronic acid ("HA")-containing
powders, as well as their manufacture and uses. We first describe
the material itself and then we describe powder formation.
[0027] HA is a naturally occurring mucopolysaccharide found, for
example, in synovial fluid, in vitreous humor, in blood vessel
walls and umbilical cord, and in other connective tissues. The
polysaccharide consists of alternating N-acetyl-D-glucosamine and
D-glucuronic acid residues joined by alternating .beta.-1-3
glucuronidic and .beta.-1-4 glucosaminidic bonds, so that the
repeating unit is -(1.fwdarw.4)-.beta.-D-GlcA-(.fwdarw-
.3)-.beta.-D-GlcNAc-. In water, non-modified hyaluronic acid
dissolves to form a highly viscous fluid. The molecular weight of
hyaluronic acid isolated from natural sources generally falls
within the range of 5.times.10.sup.4 up to 1.times.10.sup.7
Daltons.
[0028] We use the term HA to include hyaluronic acid as described
above and any of its hyaluronate salts, including, for example,
sodium hyaluronate (the sodium salt), potassium hyaluronate,
magnesium hyaluronate, and calcium hyaluronate. We also mean to
include HA in chemically modified ("derivatized") form.
Specifically, we prefer the HA/CMC material used in Genzyme's
Seprafilm.RTM. and Sepramesh.RTM. products. General disclosures of
suitable materials can be found in U.S. Pat. Nos. 6,235,726,
6,030,958 and 5,760,200, each of which is hereby incorporated by
reference. "HA" means a substance containing hyaluronic acid,
including hyaluronic acid that has been modified, cross-linked or
combined with other substances.
[0029] Further background regarding derivatized HA, Danishefsky et
al., 1971, Carbohydrate Res., Vol. 16, pages 199-205, describes
modifying a mucopolysaccharide by converting the carboxyl groups of
the mucopolysaccharide into substituted amides by reacting the
mucopolysaccharide-with an amino acid ester in the presence of
1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride ("EDC")
in aqueous solution. They reacted glycine methyl ester with a
variety of polysaccharides, including HA. The resulting products
are water-soluble; that is, they rapidly disperse in water or in an
aqueous environment such as is encountered between body
tissues.
[0030] Proposals for rendering HA compositions less water-soluble
include cross-linking the HA. R. V. Sparer et al., 1983, Chapter 6,
pages 107-119, in T. J. Roseman et al., Controlled Release Delivery
Systems, Marcel Dekker, Inc., New York, describe modifying HA by
attaching cysteine residues to the HA via amide bonds and then
cross-linking the cysteine-modified HA by forming disulfide bonds
between the attached cysteine residues. The cysteine-modified HA
was itself water-soluble and became water insoluble only upon
cross-linking by oxidation to the disulfide form.
[0031] De Belder et al., PCT Publication No. WO 86/00912, describe
a slowly-degradable gel, for preventing tissue adhesions following
surgery, prepared by cross-linking a carboxyl-containing
polysaccharide with a bi- or polyfunctional epoxide. Other reactive
bi- or polyfunctional reagents that have been proposed for
preparing cross-linked gels of HA having reduced water solubility
include: 1,2,3,4-diepoxybutane in alkaline medium at 50.degree. C.
(T. C. Laurent et al., 1964, Acta Chem. Scand., vol. 18, page 274);
divinyl sulfone in alkaline medium (E. A. Balasz et al., U.S. Pat.
No. 4,582,865, (1986); and a variety of other reagents including
formaldehyde, dimethylolurea, dimethylolethylene urea, ethylene
oxide, a polyaziridine, and a polyisocyanate (E. A. Balasz et al.,
U.K. Patent Appl. No. 84 20 560 (1984). T. Malson et al., 1986, PCT
Publication No. WO 86/00079, describe preparing cross-linked gels
of HA for use as a vitreous humor substitute by reacting HA with a
bi- or polyfunctional cross-linking reagent such as a di- or
polyfunctional epoxide. T. Malson et al., 1986, EPO 0 193 510,
describe preparing a shaped article by vacuum-drying or compressing
a cross-linked HA gel.
[0032] The above references generally disclose how to obtain the
material in particulate form suitable for hydration to produce a
gel. Generally, to produce powders suitable for use according to
the present invention, the raw material obtained from chemical
processing is precipitated as described in various references cited
above, dried, and milled using standard milling techniques to
eliminate clumps and reduce particle size.
[0033] Particle size control is achieved by sieving the milled
particles. The powder is placed in a series of sieves with varying
size screen openings. The sieves are then agitated by hand or
machine until the powder is either captured on a screen or allowed
to pass through. Varying ranges of particle sizes can be collected.
The particle size distribution can be measured by weighing all of
the sieved portions or by particle sizing equipment such as laser
diffraction particle sizers.
[0034] A distribution of the maximum dimension of powder particles
can be obtained by sieving or particle sizing equipment such as
laser diffraction particle sizers.
[0035] We generally prefer a range of particles sizes between 70
.mu.m and 600 .mu.m, although we have tested particles outside that
range and they may work in some circumstances, particularly when
applied directly from a shaker or a relatively short spray tube to
an open operating field. If the particles are too small, say below
60 .mu.m, they have a tendency to make a "cloud", rather then to be
entrained in a controllable airflow that can be effectively
sprayed.
[0036] The cloud diffuses rather than flows and is difficult to
control its position in the wound, e.g. the abdomen. If on the
other hand the particles are too large, they will not be
effectively entrained in the airflow. We prefer to keep the maximum
particle dimension below 1 mm and preferably below 600 .mu.m for
spraying. Desirably most particles are between about 35 .mu.m and
425 .mu.m in size. One specific particle size distribution that can
be used as a reference is: fewer than about 15% of the particles
with >425 .mu.m; about 30% having a particle size less than
about 425 .mu.m; and about 10% having a particle size less than 38
.mu.m. For applications that involve spraying the particles through
a relatively narrow conduit, e.g., in a laparoscopic application,
clogging can be an issue. This is particularly true if the conduit
contains airflow control structures such as swirl inducers. For
these applications, tighter manufacturing controls can be imposed.
It is also desirable to avoid particles that are so large that they
form granules (e.g., a dimension over 1 mm) that do not readily
form a uniform coating on the wound location.
[0037] By way of example, and not as a limitation, the procedure of
FIG. 8 may be used to produce, package and sterilize the powder.
The HA-CMC powder is sieved to retain powder between sieves sized
at 425 microns and approximately 100 microns. For example, sieved
200 g aliquots are mixed on a mechanical shaker until 458 g of
total sieved HA-CMC is obtained. The powder is agitated using
mechanical shaking device. The powder from the desired particle
size range is collected and mixed together to provide a more
uniform powder with respect to the powder's physical properties.
This mixing step may be performed directly after sieving as
indicated or it may be moved to just before the filling operation.
Once mixed, the powder is dispensed into moisture permeable bags
(e.g., polyethylene) which retain the powder but allow the powder
to release moisture during the subsequent (DHT) step. This
De-Hydrothermal Treatment (DHT) step is designed to heat the powder
for a minimum of six hours at 100.degree. C..+-.5.degree. C. After
the DHT step, the powder is equilibrated in an area controlled for
temperature and humidity. The length of this equilibration step is
chosen to provide a steady state condition with respect to moisture
resulting in a minimal (<1%) weight change during the filling
operations. For example, equilibration with ambient humidity (e.g.,
40% relative humidity) continues for 32 hours. The HA-CMC powder is
dispensed into a vial to be used to fill a device described
elsewhere herein, e.g., having a nominal fill size of 0.5, 1.0 and
2.0 grams. Additional powder is added to compensate for the water
content of the powder, filling tolerances and the inability to
dispense all of the powder. The vials are then packaged in
containers that provide a moisture barrier and a sterile barrier,
and the materials, which in turn is packaged for bulk
sterilization. The product is gamma irradiated at 25-40 kilograys,
and appropriate quality control is performed.
[0038] Methods and Apparatus For Applying the Powder
[0039] The most straightforward method of applying the powder is
from a shaker having orifices sized to release it. This method is
suitable where a relatively open operating field is available to
the surgeon. It can be used for coating the underlying viscera
prior to implanting a mesh prosthesis in such a wound.
[0040] Alternatively, the powder may be entrained in an airflow
directed to the wound location where adhesion prevention is
desired. FIGS. 1-7 show various spray apparatus that can be used
for this purpose. In FIG. 1, a handgrip sprayer 10 includes a
squeeze bulb 12 positioned in the grip 13. The squeeze bulb has an
inlet valve 14 and a conduit 15 connected to a powder reservoir 16.
A backflow prevention valve 17, e.g., a flapper valve, prevents
suction of powder into the squeeze bulb. Powder 20 sits in the
bottom of reservoir 16. As squeeze bulb 12 is squeezed, air flows
into reservoir 16 through conduit 15 via valve 17. The air flows
through the powder, entraining it in the airflow that exits via
conduit 22. The beginning of conduit 22 within reservoir 16 is
positioned at the top of the reservoir, spaced away from the powder
and the end of conduit 15. A spiral diffuser 24 positioned in
conduit 22 imparts a radial component to the airflow, so that the
airflow and the entrained powder spread out as they leave conduit
22 at the wound site.
[0041] Alternative delivery methods are shown in FIGS. 2-7. FIG. 2
shows a standard aerosol canister 30 that includes a source of
pressurized gas (e.g. a CO.sub.2 canister) and an internal
reservoir (not shown) containing the powder to entrain the airflow
from the canister. Pressure is released by activating valve 31,
which releases powder entrained in a flow of pressurized gas
through exit conduit 29.
[0042] FIG. 3 shows an alternative powder reservoir configuration
in which the incoming airflow is provided via a conduit 32 that
enters the top of the reservoir 34 through a hole in a stopper/cap
35 and extends to the bottom. Airflow with entrained powder exits
via a second conduit 36 at the top of the reservoir. Airflow may be
provided to such a reservoir by a pressurized gas canister 39 as in
FIG. 6 or by a squeeze bulb 41 as in FIG. 7.
[0043] FIG. 4 shows an alternative squeeze bulb 49/handgrip 51
device 40 having the reservoir 42 positioned so that it can be
inserted and removed without inverting the device. Incoming air
conduit 44 extends into the powder that is entrained in the airflow
as the airflow exits through conduit 46.
[0044] FIG. 5 shows an integral squeeze bulb 60/powder reservoir
62, in which the airflow-entrained powder is forced through the
squeeze bulb to the delivery conduit. Powder reservoir 50 is
removably inserted in a recess in the back of squeeze bulb 52.
Squeezing bulb 52 forces air through orifice 54 and the powder is
entrained in airflow exiting through conduit 56 that communicates
with the delivery conduit 58.
[0045] Advantageously, the surgeon needs only one hand to hold the
grip and squeeze the bulb.
[0046] The coating of the sprayed powder should have a density
greater than 2 mg/cm.sup.2. Preferably the coating density should
be at least 2.5 mg/cm.sup.2 or even greater, e.g., 5 mg/cm.sup.2.
If the coating is too thick it may obscure the operating field and
cause other complications. If the coating is too thin it may be
less effective.
[0047] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, a commercial spraying device
is sold by Richard Wolf GmbH, Postfach 1164 75434 Knittlingen
Germany. Accordingly, other embodiments are within the scope of the
following claims.
[0048] Applicants note that some unclaimed aspects of the spray
devices disclosed herein may have been contributed by other
individuals, such as the inventors of the above-referenced
application entitled Powder Delivery Device.
* * * * *