U.S. patent application number 13/565154 was filed with the patent office on 2012-11-22 for medical microbubble generation.
Invention is credited to Adrian Blenkinsop, Phillipe Genereux, James A. Keenan.
Application Number | 20120296208 13/565154 |
Document ID | / |
Family ID | 41265101 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120296208 |
Kind Code |
A1 |
Keenan; James A. ; et
al. |
November 22, 2012 |
Medical Microbubble Generation
Abstract
Medical apparatus and processes controllably generate medically
useful micro or nano bubbles of medically desirable and
controllably selectable size, size distribution, homogeneity and
concentration (and/or other key bubble parameters) for patient
infusion, and/or which may incorporate therapeutic or other agents
for patient infusion and/or may be combined with therapeutic or
other agents prior to infusion into patients. The bubble generation
apparatus and processes controllably permit the adjustment and
selection of key bubble parameters through bubble generation
actuation and orientation techniques and through selection of
bubble fluid compositions in order to facilitate medical research
and/or to optimize treatment for imaging, therapy, sonoporation,
inertial and non-inertial cavitation, and acoustic activation,
among other medical uses. Disposable cartridges containing such
bubbles are provided and may include means for patient
infusion.
Inventors: |
Keenan; James A.; (Ottawa,
CA) ; Blenkinsop; Adrian; (Ottawa, CA) ;
Genereux; Phillipe; (Ottawa, CA) |
Family ID: |
41265101 |
Appl. No.: |
13/565154 |
Filed: |
August 2, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12115299 |
May 5, 2008 |
8257338 |
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13565154 |
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11588995 |
Oct 27, 2006 |
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12115299 |
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Current U.S.
Class: |
600/432 ;
600/431; 604/24 |
Current CPC
Class: |
G01R 33/5601 20130101;
A61K 49/223 20130101; A61B 2017/320069 20170801; B01F 5/0685
20130101; A61B 6/032 20130101; A61M 5/007 20130101; B01F 15/0225
20130101; A61N 5/1001 20130101; A61M 37/00 20130101; B01F 13/0023
20130101; B01F 11/0071 20130101; A61M 37/0092 20130101; A61B 8/481
20130101 |
Class at
Publication: |
600/432 ;
600/431; 604/24 |
International
Class: |
A61M 37/00 20060101
A61M037/00; A61B 8/00 20060101 A61B008/00 |
Claims
1. A medical bubble generator device producing medically useful
bubbles of medically desirable size, size distribution,
concentration and homogeneity, comprising: a base station; a cradle
rotatably mounted to the base station; a disposable cartridge
removably mounted to the cradle; said cradle including first and
second fluid delivery means mounted for rotation with said cradle;
said cartridge including first and second fluid vessels and a
bubble generating module intermediate said first and second fluid
vessels that are connected along a flow path; and said cradle
adapted to selectively orient the removable cartridge and said
first and second fluid delivery means adapted to controllably move
fluid through the first and second fluid vessels of the removable
carriage when it is in a selected orientation so as to produce said
medically useful bubbles of medically desirable size, size
distribution, concentration and homogeneity in said removable,
disposable cartridge.
2. The invention of claim 1, wherein said first and second fluid
delivery means are first and second linear actuators.
3. The invention of claim 2, wherein said cradle is manually
adapted to selectively orient the removable cartridge and said
actuators are manually adapted to controllable move fluid through
the removable cartridge when in a selected orientation so as to
produce said medically useful bubbles of medically desirable size,
size distribution, concentration and homogeneity in said removable,
disposable cartridge.
4. The invention of claim 2, wherein said cradle is adapted to
selectively orient the removable cartridge in response to a
programmable controller and said actuators are adapted to
controllable move fluid through the removable cartridge when in a
selected orientation in response to said programmable controller so
as to produce said medically useful bubbles of medically desirable
size, size distribution, concentration and homogeneity in said
removable, disposable cartridge.
5. The invention of claim 2, wherein at least one of said rotatable
cradle and linear actuators are operated to provide at least one
cycle of reciprocating flow such that each cycle fluid is caused
first to flow in one direction along said flow path out of one and
into the other one of the fluid vessels via the bubble generating
module of said removable, disposable cartridge and then caused to
flow along said flow path of said removable, disposable cartridge
in a second direction counter to and opposing said first direction
out of the other one and into the first one of the fluid vessels
via the bubble generating module in such a way that first the one
and then the other of the first and second fluid vessels of the
removable, disposable cartridge is vertically oriented when fluid
is caused to flow in the first and second directions.
6. The invention of claim 5, wherein said first and second fluid
vessels and intermediate bubble generating module are in-line first
and second fluid vessels and intermediate bubble generating
module.
7. The invention of claim 6, wherein said rotatable cradle is
operated to invert the removable, disposable cartridge each half
cycle of a reciprocal cycle.
8. The invention of claim 6, wherein said bubble generating module
of said in-line first and second fluid vessels and intermediate
bubble generating module consists of a single, capillary tube and a
single mix chamber in spaced apart relation to said capillary
tube.
9. The invention of claim 2, wherein at least one of said linear
actuators is operated to so move fluid along said flow path of said
removable, disposable cartridge as to purge unwanted components
including foam and undesirably large bubbles from said medically
useful bubbles of medically desirable size produced in said
removable, disposable cartridge.
10. The invention of claim 2, wherein for an initial reciprocal
cycle at least one of the cradle and linear actuators are operated
to reciprocally move fluid along said flow path of the removable,
disposable cartridge in the first and second directions at first
and second comparatively high and comparatively low speeds to avoid
damaging sensitive fluid components, the comparatively low speed
set by a speed threshold beyond which sensitive fluid components
may be damaged, and are operated for at least one additional
reciprocal half cycle to move fluid along said flow path of the
removable, disposable cartridge in at least one the first and
second directions at speeds below the speed threshold for damaging
sensitive fluid components to produce said medically useful bubbles
of medically desirable size, size distribution, concentration and
homogeneity.
11. The invention of claim 9, wherein said cradle is operated to so
rotate said removable cartridge as to increase the concentration of
said bubbles produced therein by a centrifuge action and wherein at
least one of said linear actuators is operated to purge unwanted
components from said increased concentration bubbles.
12. The invention of claim 9, wherein, in addition to said
medically useful bubbles, unwanted components are contained in said
removable cartridge, and wherein said cradle is operated to so
rotate said cartridge as to separate the unwanted components from
said medically useful bubbles by a centrifuge action.
13. The invention of claim 12, wherein said unwanted components
include an unbound drug.
14. The invention of claim 1, wherein said first and second fluid
vessels are comparatively expensive and comparatively inexpensive
first and second comparatively high and comparatively low burst
pressure syringes.
15. The invention of claim 2, wherein said at least one cycle of
reciprocating flow along said flow path is accomplished at a
predetermined, comparatively high speed, wherein the first and
second fluid vessels have a bore size, wherein said linear
actuators have a maximum speed, and wherein a combination of
actuator speed and bore size is selected such that comparatively
larger bore sizes are selectively combined with comparatively
slower linear actuator speeds to provide said predetermined,
comparatively high speed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This invention is a divisional application of allowed,
co-pending, commonly assigned U.S. utility patent application
entitled Medical Microbubble Generation, Ser. No. 12/115, 299,
filed May 5, 2008, of the same inventive entity as herein, which is
a continuation-in-part of co-pending, commonly-assigned U.S.
utility patent application entitled Microbubble Medical Devices,
Ser. No. 11/588,995, filed Oct. 27, 2006, of James Keenan, each
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention is drawn to the field of medical microbubble
generation, and more particularly, to medical microbubble
generating apparatus and processes generating medically useful
bubbles with medically desirable properties, and to disposables
containing infusates of such bubbles that are produced by the
microbubble generating processes.
BACKGROUND TO THE INVENTION
[0003] Gas-filled microbubbles are a proven contrast agent, a means
to enhance ultrasound imaging for medical diagnosis and in
particular echocardiograms. They are infused into the bloodstream
and, as they pass beneath the transducer, the ultrasound image is
brightened and vascular details are revealed due to their echogenic
properties. Microbubbles may also be used for therapeutic
applications. This includes disruption of bubbles with ultrasound
in order to permeabilize tissue and therefore enhance drug uptake
and efficacy. This technique has been referred to as acoustic
activation, sonoporation, contrast-mediated drug delivery, inertial
cavitation and non-inertial cavitation.
[0004] A variety of acoustically activated drug delivery systems
exist including gas bubbles combined with drugs, drugs encapsulated
in microspheres, biodegradable polymer and drug solution gas
bubbles, drug impregnated microsponges, injectable nanoparticles
such as vesicles, micelles, and liposomes, and other drug carrying
particles, bubbles, or spheres that permit acoustic activation of
therapeutic agents.
[0005] Acoustically activated drug delivery systems are typically
administered to a patient and then activated by extracorporeal
ultrasound to increase the permeability of cell membranes to allow
drugs to better penetrate cells, enhance drug uptake, and hence
improve the treatment efficacy.
[0006] Acoustic activation may permit localized drug delivery. The
physician may apply ultrasound once the drug and cavitation nuclei,
typically microbubbles, are delivered to a point of interest within
a patient, in order to release the drug at the disease site.
Localized drug delivery permits a high dosage of toxic drugs to
improve treatment effectiveness and may minimize negative side
effects to healthy tissue. Permeabilization of tissue in order to
increase drug uptake may or may not be done in combination with
localized delivery.
[0007] Focused acoustic activation may permit localized drug
delivery. The therapeutic agent and microbubbles may be
administered systemically within a patient and special Focused
ultrasound used to locally sonicate an area of interest, such as a
tumour, in order to permeabilize tissue within the disease site.
The therapeutic agent may be administered to the brain through the
carotid artery and special trans-skull Focused ultrasound used to
locally sonicate an area of interest in order to overcome the blood
brain barrier and permit effective drug treatment.
[0008] Ultrasound energy may cause gas microbubbles to resonate or
burst into smaller fragments, and may induce bubble resonance that
physically deforms cell membranes, or cavitation, or
microstreaming, or the perforation of cell membranes. Bubble
resonance is typically described as sonoporation or non-inertial
cavitation, while the bubble destruction is described as inertial
cavitation.
[0009] The therapeutic agents may be chemotherapy drugs, gene
therapy, fusion proteins, and other agents.
[0010] Direct injection of chemotherapy drugs into tumours is
typically not done, as this does not improve patient outcome.
Cancers may develop resistance to drugs and render chemotherapy
useless. Acoustic activation researchers have destroyed human,
drug-resistant tumours in rodents using cavitation nuclei and
ultrasound.
[0011] Acoustic activation technology shows promise for the
treatment of drug resistant cancer tumours, vascular disease,
neurological diseases, and other diseases. Efficacy may be enhanced
by infusing drugs with bubbles and enhancing cell permeability with
ultrasound energy. Further benefits may be obtained by infusing
transient gas microbubbles in combination with acoustically
activated drug delivery release systems to enhance the local
cavitation effects.
[0012] Presently, acoustically activated drug delivery systems are
typically hard-shelled, persistent, gas microbubbles formulated in
a pharmaceutical setting. They are designed to persist through to
administration to a patient. Such products are required to maintain
integrity through the shock, vibration, and temperature changes of
transportation and to persist over time through to administration.
Such formulations may include complex design and processing
features, for example, are typically lipid, polymer, or polymer and
solvent based. However, these persistent systems must also
dissipate or degrade in the patient once administered and
activated. These polymers and any other components are required to
biodegrade with minimal negative side effects.
[0013] Acoustically activated drug delivery systems may range in
size from nano scale, sub micron, up to 1000 microns, with a one to
ten micron size typical. Size preference depends upon the resonant
frequency, or a harmonic, of the bubble or particle to be activated
at a particular ultrasound frequency, and may also depend upon the
desired release rates of the encapsulated drugs. Increased size
uniformity would encourage effective and more complete
activation.
[0014] Acoustic activation techniques include inertial cavitation,
where gas microbubbles are destroyed by ultrasound energy and
bubble shell fragments perforate cells to create nano sized
openings, and non-inertial cavitation or sonoporation, where
ultrasound energy causes bubbles to resonate. Researchers have
demonstrated in vivo therapeutic enhancement with both techniques.
In addition, sonophoresis involves the application of ultrasound,
or ultrasound and cavitation nuclei such as microbubbles, to
increase the permeability of surface cells, such as the skin or
cornea, in order to improve the delivery of topically applied
drugs.
[0015] In the field of oncology, chemotherapy is typically
administered intravenously for systemic treatment. Some localized
drug delivery techniques are practised, for example, targeted
drugs, shunting techniques to direct a drug through a tumour
vasculature, direct ethanol or acid injection for ablation of liver
tumours, and interoperative peritoneal techniques including
hyperthermic intraoperative peritoneal chemotherapy (HIPEC) where
chemotherapy is heated and poured directly into the abdomen during
open surgery in order to treat tumours too small to be visually
detected.
[0016] In terminal cases, drug treatment may be ineffective as the
metastasis of the disease causes it to reappear after initial
chemotherapy cycles and the debilitating side effects of systemic
chemotherapy preclude repeat systemic chemotherapy administration
at effective dose levels. As well, a cancer may have inherent or
developed drug resistance.
[0017] Promising new medicines, in particular gene therapy drugs,
may be unsuitable for clinical use due to inadequate delivery
techniques and other new drugs may possess unduly high
toxicity.
[0018] Therefore the following needs exist in oncology: a means to
enhance locally improved uptake of chemotherapy in a tumour in
order to achieve effective treatment with less dose and toxicity, a
means to overcome drug resistance, and a means to effectively
deliver new medicines.
[0019] Oncologists do not currently have a means to provide
patients with a flexible, acoustically activated therapy, i.e. the
means to enhance a variety of drugs, or combination of drugs, with
improved drug uptake and efficacy and reduced side effects.
[0020] High intensity Focused ultrasound (HIFU) is a means to
induce cell necrosis in diseased tissue, for example to destroy
tumours through heat ablation. Heat ablation probes typically
require about fifteen minutes in which to heat up to effective
ablation temperatures and a similar cool down period. This duration
may preclude treatment if patients are in overall poor health and
require a number of tumours to be destroyed, add to the cost and
invasiveness of the technique, including anaesthesia requirements.
A means to reduce treatment duration is desirable.
[0021] In a serious pandemic, effective vaccines may be developed
but until sufficient quantities are available medical authorities
may be unable to treat all effected patients. A means to maximize
the number of patients treated with a limited supply of vaccine
would be highly desirable. This could be accomplished through
enhanced delivery techniques, for example direct vaccine delivery
to the spleen combined with microbubbles and acoustic activation in
order use less vaccine dose per patient.
[0022] Accordingly, there is a need for medical bubble generating
apparatus and processes controllably providing medical bubbles
(micro and nano) useful for therapy, sonoporation, inertial and
non-inertial cavitation, acoustic activation, targeted delivery and
ultrasound imaging, among other medical uses, that have medically
desirable and selectable sizes, size distributions, concentrations
and homogeneities, among other key bubble parameters.
SUMMARY OF THE INVENTION
[0023] Medical bubble generating apparatus and processes are
disclosed providing medical bubbles useful for therapy,
sonoporation, inertial and non-inertial cavitation, acoustic
activation, targeted delivery and ultrasound imaging among other
medical uses, that have medically desirable and selectable sizes,
size distributions, concentrations and homogeneities, among other
key bubble parameters.
[0024] Novel bubble generating means are disclosed: a capillary
tube and mix chamber system with various reciprocating,
orientation, and actuation features including a purge cycle and a
centrifuge cycle in order to control and adjust key bubble
parameters. These parameters include mean bubble size, size
distribution, concentration (bubbles/unit volume), and
concentration homogeneity throughout the carrier liquid, and
optimizing of such parameters will result in more effective
acoustic activation.
[0025] The medical device comprises a fluid vessel for holding a
fluid or fluids, a fluid delivery means operatively connected to
the fluid vessel for applying a pressure and causing the fluid or
fluids to travel a flow path, and a bubble generating means for
generating bubbles comprised of the fluid or fluids. The fluid or
fluids passing through the bubble generating means, which may be
comprised of a carrier liquid and a gas head space, is termed
herein as "bubble fluid". The bubbles generated are micro or nano
sized and typically include shell and globule components.
[0026] The bubble fluid may include a suitable gas for in vivo use,
such as, but not limited to, perfluorocarbons (pfc), sulfur
hexafluoride, air, osmotic agents such as nitrogen, or combinations
of different gas types. The bubble fluid may include a suitable
bubble shell material for in vivo use, such as, but not limited to,
surfactants, lipids, polymers, proteins, or combinations of
materials.
[0027] The fluid delivery means causes fluid in the vessel to
travel a flow path, usually along a conduit or vessel such as a
syringe. The fluid delivery means may be a plunger on a standard
medical syringe, a syringe pump, variable speed fluid transfer
pump, peristaltic pump, or other means to pump fluids, and also
contemplates pressurization in combination with regulators, for
example, compressed gas with a gas regulator.
[0028] The fluid delivery means may be manually actuated, driven by
mechanical means such as compression or extension springs, or other
mechanical methods, by electro-mechanical means such as an electric
motor, solenoid drive, programmable syringe pump, or other
electro-mechanical means, or by pneumatic or hydraulic means. Where
the fluid is a compressed gas, the fluid delivery means may include
compressed gas force and suitable regulators. A variety of means
are contemplated and may be selected depending on a variety of
factors such as the manner of operation of the bubble generating
means, the size of the bubbles, the relative viscosity of the
bubble fluid and carrier fluid, and other factors, as will be
appreciated.
[0029] The bubble fluid or fluids may be caused to travel a flow
path into an additional fluid vessel or vessels. A fluid delivery
means operatively connected to the fluid vessel or vessels for
applying a pressure may cause the fluid or fluids to be
reciprocated back along the flow path and bubble generating means
to the first fluid vessel and this reciprocating fluid flow may be
repeated for a plurality of cycles and/or at different flow rates
so as to provide medically useful microbubbles of medically
desirable side, size distribution, concentration and homogeneity
depending on the composition selected for the bubble and/or other
fluids and/or on the medical application. A predetermined number of
reciprocal cycles (1 or more) and reciprocal half cycles (even,
odd, or zero) determined to controllably provide preselected,
medically desirable bubble properties for different medical
applications may be employed.
[0030] The fluid vessel or vessels, flow path, and bubble
generating means may be reoriented, either manually or through
electromechanical, pneumatic, hydraulic, or other actuation means,
during bubble generation or during a purge cycle in order to
optimize the bubble parameters. In one presently preferred
embodiment, the fluid or fluids are caused to travel a flow path
oriented in a vertical direction with the bubble fluid driven from
top to bottom in order to utilize bubble buoyancy to ensure a
consistent bubble concentration distribution throughout the carrier
fluid. In one presently preferred embodiment, the fluid vessel or
vessels and bubble generating means are arranged in-line in a
disposable, removable cartridge which is vertically oriented and
inverted every half reciprocal cycle in order to utilize bubble
buoyancy and in another presently preferred embodiment, the fluid
vessel or vessels and bubble generating means are arranged in a
disposable, removable cartridge having a U-shaped cartridge, where
the bubble generating means is provided along the base of the
U-shape and each of the one or more fluid vessel or vessels is
vertically oriented along another one of the legs of the U-shaped
disposable, removable cartridge.
[0031] The bubble fluid may be combined within a second or
multiplicity of fluids. Additional fluids may be contained within a
second vessel or within a conduit into which both the bubble fluid
and the additional fluid flows.
[0032] A disposable, removable cartridge containing microbubbles
(or nano bubbles) generated in accord with the present invention
may be used with injection means for delivering the bubble fluid
into a body at a desired location, for example, into a tissue mass,
tumour, vascular network, muscle, skin, organ, or other suitable
structure, depending on the application.
[0033] Ultrasound may then be used to image the bubbles in vivo and
to disrupt, rupture, resonate, or otherwise activate the bubbles
(acoustic activation) at a point of interest.
[0034] The injection means includes a hollow needle, catheter,
tube, or other surgical instrument that can be inserted within a
body to a point of interest, for example, into a tissue mass,
tumour, muscle, skin, organ, vein, artery, or other suitable
structure, depending on the application, and is structured to
permit fluid flow. The injection means could include pouring of the
bubble fluid directly from a fluid vessel into the body during open
surgery. The term "injection means" is to be broadly understood as
including various means for introducing a fluid into a body,
including by active injection or passive permeation, or otherwise
by infusion.
[0035] The bubble fluid may be a liquid or gas, including in the
form of a solution, a suspension, a vapour, other fine particulate
solids dissolved in a liquid vehicle, a combination, or the like,
provided that it is flowable. This fluid may be added to a second
fluid which may also be in the form of a solution, a suspension, a
vapour, other fine particulate solids dissolved in a liquid
vehicle, a combination, or the like, provided that it is flowable.
Thus, the device may be used to generate gas bubbles within a
liquid carrier, liquid bubbles/droplets within a liquid carrier,
liquid bubbles/droplets within a gas carrier, or gas bubbles within
a gas carrier. The device may be used with liquefied gas.
[0036] The fluid vessel is any vessel that can hold and dispense
fluid. For example, the vessel may be in the form of a syringe and
the fluid delivery means may be in the form of a plunger for the
syringe or a pump. As another example, the fluid vessel may be in
the form of a compressed gas vessel and the fluid delivery means in
the form of a compressed gas force and suitable regulators. The
term "container" may be understood as interchangeable with the term
"vessel".
[0037] The fluid vessel may contain a therapeutic fluid or a
carrier fluid. A therapeutic fluid may be a therapeutic liquid,
such as a liquid drug or drug in solution, or contain a therapeutic
agent suspended, dissolved, carried, or otherwise conveyed in a
suitable liquid vehicle including drug eluting microspheres
suspended in a fluid and radiolabelled isotopes. A therapeutic
agent may include a variety of drug compounds, or other medicinal
or non-medicinal substances, minerals, vitamins, biotherapeutics,
vaccines, organic or inorganic substances, imaging-enhancement
substances, radioactive substances, and the like, that can be
carried in the liquid or gaseous fluid.
[0038] The carrier or bubble fluids may include additives
chemically compatible with specific therapeutic agents, for example
an alcohol-compatible surfactant. This may permit acoustic
activation of treatments such as direct ethanol or acid injection
in tumours, or injection of liquid radioisotopes or radioactive
particles in suspensions.
[0039] The bubble fluids may include charged compounds, for example
cationic surfactants, in order to enhance drug binding to or drug
encapsulation within bubbles or to improve drug effectiveness, for
example to enhance transfection of gene therapies.
[0040] The medical microbubble generating apparatus of the present
invention may be configured as a table-top or floor-supported unit,
locally mounted, supported on patient body parts, or configured in
other means suitable to a clinical setting. The apparatus may be
connected to building utilities, for example to a hospital oxygen
gas supply line.
[0041] The medical microbubble generating apparatus of the present
invention may be comprised of a bubble generating means, for
example a sterile, single-use removable, disposable cartridge, and
a repeat-use base station, for example to provide fluid delivery,
adjust orientation, and incorporate sensors and controls to ensure
appropriate bubble generation. The removable, disposable cartridge
preferably includes a fluid vessel or vessels, a bubble fluid or
fluids, and a bubble generation means or module, for example a
capillary tube or tubes and mix chamber or chambers. The medical
microbubble generating apparatus in one presently preferred
embodiment includes means to deliver fluid, to adjust the fluid
delivery actuation, and to orient the fluid or fluids in the
consumable on demand in order to optimize or adjust bubble
parameters.
[0042] In one presently preferred embodiment wherein the fluid
vessel and bubble generation means are arranged in-line along a
flow path, the medical microbubble generating apparatus positions
the removable, disposable cartridge or consumable in multiple
orientations in order to use buoyancy and gravity to adjust bubble
parameters.
[0043] Sensors in the medical microbubble generating apparatus may
be used to detect leaks, plugs, or other undesirable defects in the
bubble generation means, for example pressure sensor or motor
current load monitors could be used to detect blockages or leaks in
the bubble generation means and to alert the operator through a
graphic user interface or alternate alarm system.
[0044] The bubble fluid may be biologically filtered using
conventional one-tenth (0.1) or two-tenths (0.2) micron filters.
The generating means may be terminally sterilized using a variety
of conventional sterilization means, for example gamma
sterilization for which gamma radiation compatible materials, for
example polycarbonates, are selected.
[0045] The medical microbubble generating apparatus may include
means to control the fluid temperature, such as refrigeration or
heating sources, temperature sensors and controls, thermal
insulating materials, and the like, to enhance the bubble
generation. Temperature control means in combination with fluid
pressure control, may enable a suitable fluid in liquid form to be
transformed into micro or nano bubbles and infused into the
patient, after which body temperature and pressure may cause the
bubbles to change to a gas form for acoustic activation. Bubbles
generated by the medical microbubble generating apparatus or device
may be heated to body temperature prior to infusion within the
patient in order to ensure that the bubble size remains constant
from generation to therapeutic use.
[0046] The therapeutic agent may be delivered to the point of
interest prior to, simultaneously with, or after the delivery of
the bubbles in a carrier fluid. The device may include fluid
reservoirs for the therapeutic agent or agents, bubble fluid or
fluids, and carrier fluid or fluids.
[0047] Devices of the present invention includes means for
providing nano or micro bubbles through patient infusion means such
as a needle or catheter, to enhance the therapeutic efficacy of a
drug.
[0048] Using apparatus, processes, and removable, disposable
cartridges of the present invention, bubbles may be generated
proximal to the procedure site, for example, within a hospital
pharmacy or operating room, including prior to or during a drug
administration procedure, and acoustically activated without
substantial delay. This may result in a less complex system and
reduce the additives needed to stabilize bubbles generated in
pharmaceutical settings, and produce more uniform bubbles. These
and other advantages will become apparent to the skilled
person.
[0049] Using apparatus, processes, and removable, disposable
cartridges of the present invention, bubble parameters, for example
concentration, composition, size, size distribution, homogeneity,
and other bubble parameters may be varied on demand, including
immediately prior to or during a drug administration procedure or
in vivo.
[0050] The bubble generating apparatus and processes of the present
invention may employ multiple, repeated fluid delivery cycles
through a bubble generation means in order to adjust bubble
parameters such as concentration and homogeneity and to improve
mixing of the components. Multiple fluid delivery cycles may permit
simplification and cost reduction of the bubble generation means,
for example the microfluidic geometry of capillary tubes, expansion
chambers, and the like. In one presently preferred embodiment, the
bubble generation module of the removable, disposable cartridge
includes spatially separated single capillary tube and single mix
chamber of comparatively smaller and comparatively larger
cross-section.
[0051] The bubble generating apparatus and processes of the present
invention may employ actuation means to adjust the orientation of
components, for example to orient the bubble generation means such
that the fluid delivery is done in a vertical orientation with the
fluid driven from the bottom up, in order to utilize buoyancy and
gravity to promote consistency in bubble parameters and to promote
desirable bubble properties, for example homogeneity.
[0052] The bubble generating apparatus and processes of the present
invention may employ adjustable fluid delivery flowrates, multiple
fluid delivery cycles of varying fluid flowrates, and component
orientation means in order to vary bubble parameters. For example,
programmable, electromechanical variants of the devices may employ
high flowrate fluid delivery through the bubble generation means,
may reorient the bubble generation means vertically for flowrate
cycles, and may vary fluid delivery flowrates and orientation in
particular cycles to purge the bubble solution of undesirable
by-products.
[0053] A purge cycle may involve a final, reduced flowrate fluid
delivery cycle after bubble generation cycles. Larger, medically
undesirable bubbles and foam are more buoyant than smaller, more
medically useful bubbles less than ten microns in diameter. The
undesirable large bubbles and foam may therefore be separated from
the medical useful bubble solution through a timed cycle and
controlled fluid delivery.
[0054] The bubble generating apparatus and processes of the present
invention may employ alternating fluid delivery flowrate cycles in
order to promote bubble concentration, homogeneity, and other
desirable bubble characteristics, in a cost effective, efficient
means.
[0055] For example, a high flowrate cycle may be alternated with a
lower flowrate cycle and the fluid vessels in the bubble generating
means may include a high burst pressure syringe to accommodate the
high flowrate cycles without fluid leaks operatively connected to a
conventional, lower-price commodity syringe for lower flowrate
cycles.
[0056] For an alternate example, fluid vessels of differing
geometries may be employed. A conventional three millilitre syringe
may be operatively connected to a ten millilitre syringe and the
bubble fluid reciprocated back along a flow path at a similar
linear actuation speed. This would induce a higher flowrate in the
cycles where the larger, fluid vessel was actuated.
[0057] The bubble generating apparatus and processes of the present
invention may employ a valve and fluid delivery system or a means
to detach and re-attach additional fluid vessels in order to
combine the bubble fluid with other fluids, for example therapeutic
agents. Additional fluids may be combined with the bubble fluid
pre, post, or during bubble generation cycles. An advantage would
be to optimize the combining or intermixing of the bubbles with
other agents. Pre-generation delivery of the bubble fluid with
other fluids would optimize combining and mixing. If the shear
stress required for bubble generation might harm a particular
agent, for example a biotherapeutic gene construct, the additional
fluid containing the agent could be delivered after higher flowrate
bubble generation cycles and intermixed at lower flowrates, or the
additional fluid could be delivered post generation.
[0058] The bubble generating apparatus and processes of the present
invention may employ means to adjust the orientation of components
at high speeds, for example to rotate fluid vessels about a fixed
access at a high speed in order to centrifuge the bubble fluid.
This will promote separation within the bubble fluid in accordance
with density. A centrifuge cycle could be used to produce high
bubble concentrations, or to separate therapeutic or other agents
combined with gas bubbles with therapeutic or other agents in the
bubble fluid carrier liquid. Additional carrier liquid could be
added to the bubble fluid post-separation. This would be useful for
targeted or toxic therapeutic agents where the combining of such
agents with the bubbles and the removal or reduction of such agents
from the bubble carrier liquid would promote treatment
efficacy.
[0059] Using bubble generating apparatus and processes of the
present invention, bubble size or persistence may be adjusted in
vivo. Different gas types are more soluble in the bloodstream and
bubbles with high density gas will persist longer in vivo.
[0060] Bubbles with less dense gas types, for example air, could be
used to create transient in vivo bubbles that permit ultrasound
image enhancement and with prompt clearance from the body. Bubbles
with denser gas, for example a perfluorocarbon, could be used to
create more persistent bubbles in vivo.
[0061] Bubbles with a mixture of low and high density gas types,
for example, an air and a perfluorocarbon(pfc) gas mixture, or
pfc's of different densities, could be used to create bubbles that
shrink in vivo and produce small, low micron or nano sized bubbles.
Small bubbles may be medically useful for imaging or disruption
with high frequency ultrasound and special Focused ultrasound
equipment. Smaller bubbles may also be desirable for particular
anatomical regions.
[0062] For example, nano sized bubbles may permit effective imaging
with special high frequency fifteen to thirty (15-30) MHz
ultrasound.
[0063] Using bubble generating apparatus and processes of the
present invention, bubble parameters, for example the ultrasound
disruption threshold of the bubbles, may be varied.
[0064] The term "ultrasound disruption threshold" is intended to
include the required ultrasound energy delivered to the bubbles in
order to induce desired therapeutic or imaging effects. Such
effects may include, for example, that the bubbles resonate or are
destroyed in order to increase cell permeabilization, that the
bubbles combined with drugs rupture in order to release drugs
locally on demand, and that the acoustic response properties of the
bubbles may be varied. Ultrasound disruption threshold is intended
to include the required ultrasound energy delivered to the bubbles
to induce sonoporation, inertial and non-inertial cavitation, and
acoustic activation.
[0065] Ultrasound energy is typically described as a combination of
parameters including intensity, which may be defined in terms of
mechanical index, pressure, decibels, or energy per surface area,
the ultrasound frequency, pulse mode, pulse repetition frequency,
pulse duration, and other parameters.
[0066] The predominant bubble characteristic that affects the
ultrasound disruption threshold is the bubble shell and in
particular the shell thickness.
[0067] Using bubble generating apparatus and processes of the
present invention, the bubble shell characteristics may be
adjusted. An additive, for example a PEG or cholesterol coating may
be combined with the shell components in order to increase the
thickness of the bubble shell. Salt may be combined with the shell
components, for example to enhance the surfactant properties of
surfactant-based shells. Salt may also reduce bubble coalescence
after generation, an undesirable process as smaller bubbles with a
consistent size distribution are typically more medically
useful.
[0068] Using bubble generating apparatus and processes of the
present invention, bubbles may be combined with agents, for example
therapeutic agents and targeting agents.
[0069] The potential benefits of combining therapeutic, targeting,
or targeted therapeutic agents to medical bubbles are to permit
local delivery to an area of interest, for example a tumour,
increased drug uptake and efficacy, reduced drug dose, reduced drug
side effects, reduced immune system interference, for example the
removal of a drug from the blood by the immune system, and
real-time monitoring of drug delivery through ultrasound contrast
imaging.
[0070] Bubbles may be combined with therapeutic, targeting, or
targeting therapeutic agents proximal to the patient procedure
site, for example in a hospital pharmacy, or order to permit the
separate shipping and storage of such agents. Biotherapeutics and
bio-targeting agents may require special handling and storage
conditions whereby there are advantages to combining such entities
with bubbles prior to patient infusion.
[0071] Bubbles may be combined with therapeutic, targeting, or
therapeutic targeting agents, for example biotherapeutic agents,
anchors, or linking agents, prior to or during bubble generation.
The bubbles may be directly combined with the therapeutic or
targeting agents during generation or by means of a staged
procedure whereby, for example, cross linkers or anchors may be
combined with micro or nano bubbles during generation and the
therapeutic or targeting agent combined with the cross linkers and
bubbles post bubble generation.
[0072] The advantage of combining therapeutic agents or anchors or
cross linkers to bubbles during generation is to increase the drug
payload per bubble through dynamic resizing of the bubbles during
generation and to ensure even drug distribution throughout the
bubble solution through the generation mixing process.
[0073] Dynamic resizing is an observed phenomenon of the bubble
generating apparatus and processors of the present invention that,
at the time of generation, the bubbles are of a larger size and
then shrink and stabilize at smaller, more medically useful sizes.
For example, at generation bubbles in the twenty to forty (20-40)
micron diameter range may encapsulate drugs or be combined with
anchors or cross linkers. Within seconds the bubbles may shrink and
stabilize to one to four (1-4) micron or nano sizes with a higher
quantity of drug encapsulated or a higher concentration of anchors
or linkers per bubble surface area than would be accomplished
through encapsulating drugs or combining anchors or therapeutic
agents to bubbles after generation at smaller, stable bubble
sizes.
[0074] Therapeutic agents may be combined with bubbles through the
encapsulating of the drug in the bubble. For those variants,
untargeted-manual delivery could be employed, whereby imaging
ultrasound could be used to locate and track the bubble and drug
combinations in the bloodstream and then to disrupt the bubbles at
the area of interest in order to achieve local drug delivery. This
untargeted-manual delivery method could also be used with those
variants where the drug is bound to the bubble shell via an anchor,
linker and/or spacer.
[0075] For variants used to encapsulate therapeutic agents within
the bubbles, therapeutic agents which are oil based, hydrophobic,
amphiphilic, soluble in oil, or possessing surfactant-like
qualities, may be readily encapsulated during generation with
surfactant based bubbles.
[0076] For variants used to bind therapeutic, targeting, or
targeted therapeutic agents to the bubble shell an anchor may be
incorporated within the shell. A linker may then be bound to the
bubble shell with a therapeutic, targeting, or targeted agent or a
spacer arm may be bound to the bubble shell and the targeting agent
bound to the spacer. The advantage of spacers would be to increase
the targeting success to the area of interest.
[0077] For example, a biotinylated anchor may be incorporated
within the bubble fluid, for example within a gas, chemical, and
carrier liquid solution, and bubble generation would then
incorporate the anchor within the bubble shells. A centrifuge purge
may then be required to separate unincorporated anchors from the
bubble carrier liquid. A generic linker such as avidin,
neutravidin, streptavidin, or HaloTag may then be bound to the
bubbles, permitting binding of a biotinylated protein, ligand, or
drug. Biotinylation can be done on carboxyl, sulfhydryl, and amine
groups
[0078] Targeting agents, such as ligands, receptors, fusion
proteins, and others, may be combined with the bubbles in order to
create targeted therapies or targeted diagnostic agents. For
therapy, the drug and targeting agents may be combined with
bubbles, infused in a patient, and these preferentially gather at
the disease site. Ultrasound energy could then be used to disrupt
the bubbles and to release the drug locally. The ultrasound could
also be used to disrupt the bubbles, to induce acoustic activation,
sonoporation, inertial cavitation, and the like, in order to
permeabilize tissue so that the drug is released locally and the
cellular uptake and efficacy of the drug enhanced.
[0079] For targeted diagnostics, a combination of targeting agents
and bubbles could be infused within a patient. These would
preferentially gather at the disease site and ultrasound imaging
enhanced, through the echogenicity of the bubbles, in order to
diagnose conditions not visible through conventional ultrasound
imaging. For example, a molecule that preferentially attached to
liver cancer could be combined with bubbles and infused into people
with hepatitis who have a higher risk of liver cancer. If tumours
were present but too small to be detectable with conventional
ultrasound, the bubbles and targeting agent would preferentially
gather at these small tumour and be detectable with the ultrasound
so that treatment could commence during the earliest, most
treatable stage of the disease.
[0080] Using methods and medical devices of the present invention
targeted diagnostics could also be used to enhance therapy. The
bubbles combined with targeting agents could be infused in order to
accumulate at the disease site. Once a sufficient concentration of
bubbles were administered a systemic drug could be administered and
the bubbles disrupted by ultrasound. This method would permit
localized permeabilization and increased drug uptake at the disease
site.
[0081] The bubbles could also be combined with ferrous particles so
that they would provide image enhancement for ultrasound and MRI.
This could be useful for research and clinical applications where
multiple imaging modalities are preferred.
[0082] Using methods and medical devices of the present invention,
bubbles may enhance therapeutic agent efficacy and safety in a
variety of means.
[0083] A therapeutic agent or agents may be administered
systemically, for example conventional intravenous administration
of chemotherapy drugs, and the bubbles delivered locally, for
example to a tumour using established ultrasound-guided needle or
catheter procedures. The ultrasound parameters may then be modified
in order to disrupt the bubbles and to permeabilize tissue in an
area of interest, for example a tumour, to increase drug uptake and
efficacy. Such a method may improve therapeutic results with a
conventional drug dose or may improve therapeutic results with a
reduced drug dose in order to lessen undesired side effects.
[0084] A therapeutic agent or agents and bubbles may both be
administered locally, for example to a tumour using established
ultrasound-guided needle or catheter procedures, and the ultrasound
parameters modified in order to disrupt the bubbles and to
permeabilize tissue in an area of interest, for example a tumour,
to increase drug uptake and efficacy.
[0085] A therapeutic agent or agents and bubbles may both be
administered systemically and special Focused ultrasound used to
locally sonicate the area of interest, for example a tumour, to
increase cell permeability and drug uptake and efficacy.
[0086] A therapeutic agent or agents and bubbles may be combined
and administered either systemically or locally and ultrasound used
to disrupt the bubbles and hence deliver drugs at an area of
interest or to deliver the drugs and to permeabilize cells and
hence increase drug uptake at the area of interest.
[0087] A therapeutic agent or agents and bubbles may be
administered in a multiplicity of doses. For example, a therapeutic
agent may be administered systemically and repeat doses of bubbles
administered locally to an area of interest, and ultrasound used to
image and verify local delivery and then to disrupt the bubbles and
hence permeabilize cells and increase drug uptake and efficacy.
[0088] Using methods and medical devices of the present invention,
bubbles may be infused within a patient and used to enhance
therapies that do not require therapeutic agents or drugs to be
administered to the body. For example, the bubbles may be used to
accelerate the heating cycle of high intensity frequency ultrasound
(HIFU) tumour ablation treatments, reduce treatment duration, and
thus reduce patient trauma and expand potential applications. The
bubbles may be used to reduce the energy required for ultrasound
systems designed to lyse fat cells through cavitation. The bubbles
may also be administered to tumours to enhance radiation treatments
such as the neo-adjuvant treatment of breast cancer where ionizing
radiation is used to reduce tumour size prior to surgery in order
to improve the odds of a successful surgical outcome and to reduce
patient trauma and scarring.
[0089] Using methods and medical devices of the present invention,
bubbles may be infused within a patient and used to characterize
tumour blood flow prior to, during, or after treatments in order to
monitor and adjust treatment efficacy and to minimize effects to
healthy tissue. Tumour treatments include radiotherapy using
external beam or brachytherapy, thermal ablation techniques, for
example radiofrequency heat probe ablation, high intensity
frequency ultrasound (HIFU) tumour ablation, MRI guided Focused
ultrasound (MRgFUS) ablation, direct or targeted chemotherapy
treatments, or cryoablation techniques.
[0090] Doppler ultrasound detection of bubbles could be used to
monitor tumour blood flow which relates to treatment efficacy. For
example, for treatment regimes requiring repeated external beam
radiotherapy doses this would permit real time adjustment of the
number of doses, dose intensity, and targeting precision. For
brachytherapy treatments this would permit real time adjustment of
radioactive seed location and treatment duration.
[0091] It is to be appreciated that reference to a "device" of the
present invention may be understood to include an "apparatus" or
"assembly", which may be incorporated into systems with suitable
adaptations.
[0092] It is also to be appreciated that the devices of the present
invention may be used in a variety of applications, including
medical diagnosis, image guided intervention, treatment, surgery,
and the like, and also may be used in a similar fashion in
veterinary applications and in animal research applications with
suitable modifications.
[0093] The term "needle" is intended to include any hollow, slender
instrument that may be manipulated to puncture or be inserted or
otherwise probe tissues, organs, cavities, or the like. The needle
may be used to introduce material into or remove material from a
patient or to perform other therapeutic or diagnostic functions.
The term needle is intended to include rods or wire-like medical
instruments, cannulas, probes, tubes and lumens, stylets, and the
like.
[0094] The term "patient" may be any suitable animal, including
humans and other mammals.
[0095] The term "catheter" is intended to include any flexible
surgical instrument for the introduction of fluids into the body,
including catheters for repeat dose drug delivery such as hickman
lines, PORTACATH.TM. lines and the like.
[0096] The fluids container may be any suitable vessel to contain
gases or liquids, such as syringes, gas tanks, a central,
building-supply, fluid source that may be connected to the device
via fluid conduit, and the like.
[0097] The fluid delivery means may be a syringe plunger actuated
manually, a syringe pump, an electro-mechanical means with which to
actuate syringe plungers, a variable speed fluid transfer pump, a
peristaltic pump, the regulated release of compressed gas, or other
suitable means to supply fluids. The delivery means may also be
driven manually or by mechanical means such as compression or
extension springs, or other mechanical methods, by
electro-mechanical means such as an electric motor, solenoid drive,
or other electro-mechanical means, or by pneumatic or hydraulic
means.
[0098] Over all, it is to be appreciated that terms used herein are
to be interpreted and understood expansively and not strictly.
[0099] In summary of its process aspect the present invention
discloses a method of generating from bubble fluid medically useful
bubbles of medically desirable size, size distribution,
concentration and homogeneity comprising the steps of reciprocally
driving the bubble fluid through and between spatially separated,
first and second fluid vessels that are connected in a flow path
via a bubble generating module in such a way that the bubble fluid
is first driven half a reciprocal cycle in a first direction along
the flow path upwardly vertically through one of the spatially
separated, first and second fluid vessels into the other one of the
spatially separated first and second fluid vessels via the bubble
generating module, and is then driven the other half reciprocal
cycle in a second direction along the flow path opposite to the
first direction upwardly vertically through the other one of the
spatially separated first and second fluid vessels back into the
first one of the first and second fluid vessels via the bubble
generating module; repeating for a predetermined number of
reciprocal half cycles said reciprocally driving fluid step so as
to produce said medically useful bubbles of said medically
desirable size, size distribution, concentration and homogeneity
together with undesirable components including foam and larger
undesirable bubbles; and removing the undesirable components from
the medically useful bubbles of medically desirable size, size
distribution, concentration and homogeneity. The predetermined
number of reciprocal half cycles is a number selected from the
group of numbers consisting of zero (0), even whole integers and
odd whole integers. In one preferred embodiment, the bubble
generating module consists of a single capillary tube and single
mix chamber of comparatively smaller and comparatively larger
cross-section.
[0100] In one embodiment where the spatially separated, first and
second fluid vessels are in-line vessels and bubble generating
module that are carried by a disposable cartridge, the reciprocally
driving fluid step through and between the in-line vessels and
bubble generating module of said disposable cartridge includes the
step of inverting the disposable cartridge between each half
reciprocal cycle of said reciprocally driving step, and, when the
predetermined number of reciprocal half cycles is an even whole
integer, the repeating said reciprocally driving fluid step through
the in-line vessels and bubble generating module of said disposable
cartridge includes the step of inverting the disposable cartridge
between each half reciprocal cycle of each said even whole integer
number of times said reciprocally driving fluid step is
repeated.
[0101] In another embodiment where the spatially separated, first
and second fluid vessels are connected in a flow path via a bubble
generating module that are arranged in a U-shape in a disposable
cartridge, the bubble generating module is arranged to form the
base of the U-shape and each of the first and second fluid vessels
is arranged to form another one of its legs which are each
vertically oriented when the bubble generating module is
horizontally orientated.
[0102] The bubble fluid includes preselected shell and globule
components selected to provide bubbles useful for acoustic imaging;
for one of sonoporation, inertial and non-inertial cavitation and
acoustic activation, and may include a shell additive to control
ultrasound disruption threshold useful for one of sonoporation,
inertial and non-inertial cavitation and acoustic activation; for
targeted delivery or untargeted-manual delivery, they may include
at least one of an anchor, linker and spacer; and/or may include
preselected shell and globule components selected to provide
bubbles useful for therapy, such as fat lysing, HIFU for tumor
ablation and radiation therapy.
[0103] In summary of its apparatus aspect the present invention
discloses a medical bubble generator device producing medically
useful bubbles of medically desirable size, size distribution,
concentration and homogeneity, comprising a base station; a cradle
rotatably mounted to the base station; a disposable cartridge
removably mounted to the cradle; said cradle including first and
second fluid delivery means mounted for rotation with said cradle;
said cartridge including first and second fluid vessels and a
bubble generating module intermediate said first and second fluid
vessels that are connected along a flow path; and said cradle
adapted to selectively orient the removable cartridge and said
first and second fluid delivery means adapted to controllably move
fluid through the first and second fluid vessels of the removable
carriage when it is in a selected orientation so as to produce said
medically useful bubbles of medically desirable size, size
distribution, concentration and homogeneity in said removable,
disposable cartridge.
[0104] In one presently preferred embodiment, the first and second
fluid delivery means are first and second linear actuators, and
said cradle and linear actuators in alternative embodiments are
adapted to be manually responsive or adapted to be responsive to a
programmable controller to selectively orient the removable to
controllable move fluid through the first and second fluid vessels
of the removable cartridge when it is in a selected orientation so
as to produce said medically useful bubbles of medically desirable
size, size distribution, concentration and homogeneity in said
removable, disposable cartridge.
[0105] In one presently preferred embodiment, the rotatable cradle
and linear actuators are operated to provide at least one cycle of
reciprocating flow such that each cycle fluid is caused first to
flow in one direction along said flow path out of one and into the
other one of the fluid vessels via the bubble generating module of
said removable, disposable cartridge and then caused to flow along
said flow path of said removable, disposable cartridge in a second
direction counter to and opposing said first direction out of the
other one and into the first one of the fluid vessels via the
bubble generating module in such a way that first the one and then
the other of the first and second fluid vessels of the removable,
disposable cartridge is vertically oriented when fluid is caused to
flow in the first and second directions.
[0106] In one embodiment the first and second fluid vessels and
intermediate bubble generating module are in-line first and second
fluid vessels and intermediate bubble generating module and said
rotatable cradle is operated to invert the removable, disposable
cartridge between each half cycle of a reciprocal cycle.
[0107] In another embodiment the first and second fluid vessels and
intermediate bubble generating module are arranged in a disposable
cartridge in a U-shape, wherein the bubble generating module forms
the base of the U-shape and each of the first and second fluid
vessels forms another one of its legs which are each vertically
oriented when the bubble generating module is horizontally
orientated.
[0108] At least one of said linear actuators may be operated to so
move fluid along said flow path of said removable, disposable
cartridge as to purge unwanted components including foam and
undesirably large bubbles from said medically useful bubbles of
medically desirable size produced in said removable, disposable
cartridge.
[0109] For an initial reciprocal cycle the cradle and/or linear
actuators may be operated to reciprocally move fluid along said
flow path of the removable, disposable cartridge in the first and
second directions at first and second comparatively high and
comparatively low speeds to avoid damaging sensitive fluid
components, the comparatively low speed set by a speed threshold
beyond which sensitive fluid components may be damaged, and may be
operated for at least one additional reciprocal half cycle to move
fluid along said flow path of the removable, disposable cartridge
in at least one the first and second directions at speeds below the
speed threshold for damaging sensitive fluid components to produce
said medically useful bubbles of medically desirable size, size
distribution, concentration and homogeneity.
[0110] The cradle may be operated to so rotate said removable
cartridge as to increase the concentration of said bubbles produced
therein by a centrifuge action and at least one of said linear
actuators may be operated to purge unwanted components from said
increased concentration bubbles.
[0111] In addition to said medically useful bubbles, unwanted
components may be contained in said removable cartridge, and the
cradle may be operated to so rotate said cartridge as to separate
the unwanted components from said medically useful bubbles by a
centrifuge action.
[0112] The first and second fluid vessels may be comparatively
expensive and comparatively inexpensive first and second
comparatively high and comparatively low burst pressure
syringes.
[0113] For at least one cycle reciprocating flow along said flow
path may be accomplished at a predetermined, comparatively high
speed, wherein the first and second fluid vessels have a bore size,
wherein said linear actuators have a maximum speed, and wherein a
combination of actuator speed and bore size is selected such that
comparatively larger bore sizes are selectively combined with
comparatively slower linear actuator speeds to provide said
predetermined, comparatively high speed.
[0114] The foregoing summarizes some of the principal inventive
apparatus and process aspects of the medical microbubble generation
of the present invention and some of its advantageous features. The
invention may be further understood by the description of the
presently preferred embodiments, in conjunction with the drawings,
which now follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0115] The accompanying drawings illustrate presently preferred
embodiments of the invention and, together with the description
that follows, serve to further explain the principles of the
invention.
[0116] FIG. 1A depicts a microbubble generating device that employs
an electromechanical actuator to generate microbubbles of varying
sizes.
[0117] FIGS. 1B-1C depicts cross-sectional views of alternate
bubble generator modules.
[0118] FIGS. 1D-1E depict an alternate U-shaped disposable,
cartridge.
[0119] FIGS. 2A, 2B depict one presently preferred embodiment of
the medical microbubble generation apparatus in accord with the
present invention.
[0120] FIG. 3 is a flow chart useful in explaining one medical
microbubble generation process in accord with the present
invention.
[0121] FIG. 4 depicts another presently preferred microbubble
generation apparatus embodiment in accord with the present
invention.
[0122] FIG. 5 is a flow chart useful in explaining a medical
microbubble generation process variation in accord with the present
invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0123] Reference will now be made in detail to various suitable
embodiments including a presently preferred embodiments of the
invention as illustrated in the accompanying drawings. It will be
understood that this description is exemplary and is to assist in
understanding the invention and the principles of operation.
[0124] FIG. 1A depicts a microbubble generating device that employs
an electromechanical actuator to generate microbubbles of varying
sizes.
[0125] A generator syringe 1 is preloaded with a surfactant saline
solution 2. The generator syringe plunger 3 is withdrawn in order
to infuse a quantity of air within the generator syringe 1 to
achieve a desired liquid to gas ratio. The generator syringe 1 may
also be preloaded with a suitable microbubble forming gas such as,
but not limited to, perfluorocarbons, sulfur hexafluoride and/or
osmotic agents such as nitrogen.
[0126] The surfactant solution 2 may be comprised of a number of
suitable, commercially available surfactants, for example
detergents, stearic or polmetic acid, or micelle-based surfactants,
in a sterile saline, a phosphate buffered saline, deionized water,
or other liquid suitable for injecting within the body. A plurality
of surfactants, for example a Span (60) and Tween (80) combination,
may be used. The surfactants may be melted, crushed, heated,
stirred, mixed, or agitated within the liquid in order to ensure
adequate solubility or distribution. The surfactant solution may
require additional heating or agitation immediately prior to use.
Agitation may be achieved by manual, mechanized, ultrasonic, or
other suitable means. The solution may contain other additives to
adjust viscosity, promote bioadhesion of the bubbles, or enhance
effectiveness of a particular therapeutic agent.
[0127] A pneumatic, electromechanical or other actuator 4 and
generator assembly 5 is connected to the generator syringe 1. The
syringes 1, 7 and generator are arranged as an in-line disposable
cartridge.
[0128] The actuator 4, driven by a programmable control system (not
shown), is used to drive the syringe plunger 3 in order to infuse
the surfactant solution 2 and gas mixture into the generator
assembly 5 at a controlled flow rate
[0129] Microbubbles are formed in the generator assembly 5 through
an in-line flow technique and a microbubble solution 6 is produced
and infused into a microbubble syringe 7 connected by an adaptor.
In different embodiments of the FIG. 1 device, reciprocation
through the generator 5 may and may not be employed.
[0130] FIGS. 1B-C depict cross-sectional views of different
generator assembly embodiments.
[0131] The generator assembly generally designated 5 is comprised
of one set or a series of capillary tubes 8, mix chambers 9, and
adaptors (not shown), which may be contained within an outer casing
(not shown). FIG. 1B depicts an in-line, single capillary tube and
single mix chamber system; FIG. 1C depicts an in-line two-stage
system. Of course, more than two stages could be employed.
[0132] The number of capillary tubes and mix chambers arranged in
series may range from one (1) of each to eight (8) of each or more.
The inner diameter of the capillary tubes may be in the order of
fifty (50) to one thousand (1000) microns with three hundred (300)
microns typical. The length of capillary tubing may vary, for
example with a first tube (0.5) to fifteen (15) cm in length and
subsequent tubes one (1) to ten (10) cm in length. The mix chamber
geometry may vary, with an inner diameter of (0.2) centimeters up
to two (2) centimeters, with (0.5) centimeters typical, and a
length of (0.05) centimeters up to five (5) centimeters, with one
(1) centimeter typical. The capillary tubes may be arranged in a
straight line or may be offset to promote the mixing of bubbles and
liquid in the mix chambers.
[0133] The capillary tubes and mix chambers may be fabricated in a
variety of methods using a variety of materials. Material selection
would permit sterilization of interior surfaces contacting the
surfactant solution that is to be infused within a patient.
[0134] Stainless steel medical needles cut to length may be used to
form the capillary tubes. The mix chambers may be machined from
sections of plastic tubing or bar stock, from material such as
acrylic or Teflon, with a through hole drilled within which to fit
the capillary tubes. Epoxy may be used to leak proof the mated
tubing sections. Syringe adaptors may be standard leak tight
adaptors such as Luer-lok.
[0135] FIGS. 1D-1E depict an alternate U-shaped disposable,
cartridge.
[0136] The U-shaped disposable, cartridge generally designated at
10 includes a bubble generator module 5 that includes one set (or a
series) of capillary tubes 8, mix chambers 9, and adaptors, not
shown. The adaptors are located on the same side of the bubble
generator module 5 and allow the generator syringe 1 and
microbubble syringe 7 to be attached to one side of the bubble
generator module 5. The spatially separated syringes 1, 7 are
connected in a flow path via bubble generating module and are
arranged in a U-shape in the cartridge 10, where the bubble
generating module 5 is arranged in the cartridge to form the base
of the U-shape and each of the syringes is arranged in the
cartridge to form another one of the legs of the U-shape. The
syringe legs are each vertically oriented when the bubble
generating module 5 is horizontally orientated.
[0137] FIGS. 2A, 2B depict one presently preferred embodiment of
the microbubble generating device of the present invention.
[0138] The microbubble generating device 20 includes a base station
generally designated 22 and a cradle 24 rotatably mounted to the
base station 22 via rotary actuation assembly generally designated
26 operatively connected to motor 28. The cradle 24 includes linear
actuators 30, 32 mounted for rotation with the cradle 24. The
linear actuators 30, 32 are controllably displaced by motor 34
operatively coupled to the linear actuators 30, 32. An in-line
disposable cartridge generally designated 36 is removably mounted
to the cradle 24. The disposable cartridge 32 includes in-line
first and second syringes 38, 40 having syringe plungers that are
connected in a fluid flow path via an intermediate bubble
generating module 42. The syringe plungers of the first and second
syringes 38, 40 are driven by the associated one of the linear
actuators 30, 32. Programmable controller 44 having graphical user
interface (GUI) 46 and input buttons 48 is operatively coupled to
the motors 28, 34. The controller 44 selectively rotates the cradle
32 to controllably orient the cartridge 36 and selectively drives
the actuators 30, 32 to controllably move fluid through the first
and second syringes 38, 40 of the removable cartridge 36 when it is
in a selected orientation. Either the actuation plates 30, 32 are
held stationary while the microbubble generation assembly
holder/cradle 24 is actuated or the holder/cradle 24 is stationary
while the actuation plates 30, 32 are actuated. In the illustrated
embodiment, the linear actuators 30, 32 are driven together. They
may be driven separately in an alternate embodiment, not shown.
[0139] The microbubble generating device 20 is loaded by placing
the disposable, removable cartridge 36 having in-line generation
syringe 38 preloaded with bubble fluid and an empty microbubble
syringe 40 connected in a flow path via an intermediate bubble
generating module 42 into the rotatable cradle 24 of the base
station 22. Once loaded, the user is prompted by the GUI 46 to
press the input/"start" button 48 and the controller 44 selectively
rotates the cradle 32 to controllably orient the cartridge 36 and
selectively drives the actuators 30, 32 to controllably move fluid
through the first and second syringes 38, 40 of the removable
cartridge 36 when it is in a selected orientation under program
control. Of course, the cradle 24 and actuators 30, 32 could be
operated manually without departing from the inventive
concepts.
[0140] Referring now to FIG. 3, generally designated at 60 is a
flowchart useful in explaining one medical bubble generation
process in accord with the present invention. In a first step 62,
the cradle is rotated to the starting position.
[0141] As shown by block 64, the in-line cartridge is removably
mounted to the rotatable cradle.
[0142] As shown by block 66, a bubble fluid preloaded in one of the
fluid vessels or generation syringe, by way of example the lower
syringe, is driven upwardly vertically through the generation
syringe and into the other fluid vessel, or empty upper syringe,
via the bubble generation module.
[0143] As shown by block 68, the cradle is then rotated so that the
cartridge is turned upside down.
[0144] As shown by block 70, the associated actuator is then
operated to drive the fluid upwardly vertically through the lower
syringe and back into the upper syringe via the bubble generating
module.
[0145] As shown by block 72, the steps 68, 70 are repeated for a
predetermined number of reciprocal half cycles in order to
controllably produce medically useful microbubbles of medically
desirable size, size distribution, homogeneity and concentration in
dependence on the number of reciprocal half cycles employed for any
given bubble fluid. Depending on the medical application and bubble
fluid employed the predetermined number of reciprocal half cycles
is a number selected from the group of numbers consisting of zero
(0), even whole integers and odd whole integers.
[0146] As shown by block 74, after the bubble fluid has been
reciprocated to and fro through the bubble generation module a
prescribed number of times to produce bubbles of medically useful
size, size distribution, concentration and homogeneity, any
unwanted components, that may include foam and larger, medically
undesirable bubbles, are allowed to separate from the medically
desirable microbubbles.
[0147] As shown by block 76, after the unwanted components have
been allowed to separate, the linear actuator is operated to purge
the unwanted components from the syringe containing the medically
desirable microbubbles together with the undesirable components
leaving only the medically useful microbubbles of medically
desirable size, size distribution, concentration and
homogeneity.
[0148] The undesirable components will rise to the top of the
cartridge. When, for example, the undesirable components are purged
from the top fluid vessel, the corresponding actuator is driven at
a comparatively slower speed than the speed used for bubble
generation in order to move the microbubbles into the bubble
generation module. The length of travel is selected to move the
medically useful bubbles through the bubble generation module into
the bottom syringe. Of course, the purge cycle could be completed
bottom-up; the corresponding actuator driven at slower speed than
during bubble formation is caused to travel a distance selected to
move the unwanted components into the bubble generation module,
which then will act as a waste receptacle, leaving the medically
useful microbubbles of medically desirable parameters in the lower
syringe.
[0149] In practice, as detailed in the examples hereinbelow, it has
been found that six (6) whole reciprocal cycles has produced
optimized bubble parameters in these examples. In general, beyond a
certain number of reciprocal half cycles no improvement in desired
bubble characteristics has been observed. Generally, this number
will be less than thirty (30) or so; typically four to six (4-6)
whole reciprocal cycles have been found to be optimal.
[0150] As shown by block 78, one or more optional centrifuge and/or
purge cycles may be employed depending on the medical application
and in dependence on the composition of the bubble fluid and other
fluid components or constituents.
[0151] As shown by block 80, the removable disposable cartridge
containing medically useful microbubbles of medically desirable
size, size distribution, concentration and homogeneity is then
removed from the cradle.
[0152] Referring now to FIG. 4, generally designated at 90 is a
block diagram illustrating another embodiment of a medical
microbubble generation apparatus in accord with the present
invention. The microbubble generation apparatus 90 includes base
station cradle 92 adapted to removably receive a disposable
cartridge. A disposable cartridge schematically illustrated by
dashed box 94 is removably received by the cradle 92. The
disposable cartridge 94 includes first and second fluid vessels 96,
98 and intermediate bubble generating module 100 that are arranged
in the removable, disposable cartridge 94 in a U-shape, where the
bubble generating module 104 is arranged to form the base of the
U-shaped cartridge and each of the first and second fluid muscles
96, 98 are arranged to form another one of it legs which are each
vertically oriented when the bubble generating module is
horizontally orientated. The bubble generating module 100
preferably consists of a single capillary tube and single mix
chamber respectively of comparatively smaller and comparatively
larger cross-section. The syringes 96, 98 include syringe plungers
schematically illustrated by double-headed arrows 102, 104 that are
respectively driven by linear actuators 106, 108. The actuators
106, 108 may be manually operated or operated in response to a
programmable controller, not shown, without departing from the
inventive concepts.
[0153] Referring now to FIG. 5, generally designated at 120 is a
flowchart useful in explaining a medical microbubble generation
process variation in accord with the present invention. In a first
step 122, the U-shaped cartridge is removably mounted in the
cradle.
[0154] As shown by block 124, bubble fluid preloaded in one fluid
vessel of the removable cartridge is driven upwardly vertically
therethrough and into the other fluid vessel via the bubble
generation module in one direction along the flow path.
[0155] As shown by block 126, the associated actuator is then
operated to drive the fluid upwardly vertically through said other
syringe and back into said one fluid vessel via the bubble
generating module reciprocally back along the flow path.
[0156] As shown by block 128, the steps 124, 126 are repeated for a
predetermined number of times in order to controllably produce
medically useful microbubbles of medically desirable size, size
distribution, homogeneity and concentration in dependence on the
number of reciprocal half cycles employed for any given bubble
fluid. Depending on the medical application and bubble fluid
employed the predetermined number of reciprocal half cycles is a
number selected from the group of numbers consisting of zero (0),
even whole integers and odd whole integers.
[0157] As shown by block 130, after the bubble fluid had been
reciprocated through the bubble generation module a prescribed
number of times to produce bubbles of medically useful size, size
distribution, concentration and homogeneity, any unwanted
components that may include foam and larger bubbles are allowed to
separate from the medically desirable microbubbles and the
corresponding linear actuator is operated to purge the unwanted
components from the syringe containing the medically desirable
microbubbles together with the undesirable components leaving only
the medically useful microbubbles of medically desirable size, size
distribution, concentration and homogeneity.
[0158] As shown by block 132, the removable, disposable cartridge
containing medically useful microbubbles (or nano bubbles) of
medically desirable size, size distribution, concentration and
homogeneity (and/or other key bubble parameters) is then removed
from the cradle.
EXAMPLE A
[0159] Six (6) reciprocal cycles with a three (3) mL bubble fluid
preload of two and one-half (2.5) mL liquid and one-half (0.5) mL
of gas produced between one (1) and two (2) (1-2)*10.sup.8
microbubbles per milliliter of one and one-half (1.5).mu. diameter
size that exhibit excellent size distribution and homogeneity.
These bubbles have been found useful for ultrasound image
enhancement and their ultrasound disruption properties have been
found useful for sonoporation, inertial and non-inertial cavitation
and acoustic activation. It may be noted, that during bubble
generation, dynamic resizing has been observed.
EXAMPLE B
[0160] Six (6) reciprocal cycles with a three (3) mL bubble fluid
preload of two and one-half (2.5) mL liquid and one-half (0.5) mL
of a fifty/fifty (50/50) mix of pfc and air produced between one
(1) and two (2) (1-2)*10.sup.8 microbubbles per milliliter of one
and one-half (1.5).mu. diameter size that exhibited shrinkage to
sub micron bubbles in vivo.
[0161] In both these examples, it was found that selecting the
number of reciprocal half cycles and selecting the actuation speeds
controllably varies the medically desirable bubble parameters. In
general, for a given bubble fluid composition, the greater the
number of reciprocal half cycles and the higher the fluid speed the
greater the concentration and the more uniform the size
distribution of the medical bubbles generated.
[0162] For a given number of cycles and fluid speed, selecting the
bubble fluid composition and chamber geometry controllably varies
the medically desirable bubble characteristics. It has been found,
for example, that increasing the number of cycles allows
simplification of the geometry of the bubble generator module.
Single stage capillary tubes and single stage mix chambers have
been employed to produce the results given in the examples above.
This not only lowers costs and simplifies construction but has been
found to promote batch to batch consistency.
[0163] While manual reciprocation (without linear actuators)
through non-vertical syringes (or other fluid vessels) is a
feasible means for generating microbubbles, it has been found that
the combination of controlled vertical orientation and linear
actuator controlled reciprocation produces microbubbles of superior
medically desirable bubble characteristics and highly superior
batch to batch consistency. The vertical orientation is a key to
attainment of batch to batch consistency. It provides for more
consistent layering in the bubble fluid components, which results
in more consistent attainment of medically desirable microbubble
parameters and allows precise purging of the undesirable components
that may include foam and larger, medically undesirable
microbubbles.
[0164] Many modifications of the presently disclosed invention will
become apparent to those skilled in the art having benefitted from
the instant specification without departing from the inventive
concepts.
* * * * *