U.S. patent application number 14/989147 was filed with the patent office on 2016-04-28 for methods for treating airways.
The applicant listed for this patent is Asthmatx, Inc.. Invention is credited to Michael BIGGS, Christopher J. DANEK, Gary S. KAPLAN, Michael D. LAUFER, Bryan E. LOOMAS, Kelly M. SHRINER, William J. WIZEMAN.
Application Number | 20160113703 14/989147 |
Document ID | / |
Family ID | 37417920 |
Filed Date | 2016-04-28 |
United States Patent
Application |
20160113703 |
Kind Code |
A1 |
DANEK; Christopher J. ; et
al. |
April 28, 2016 |
METHODS FOR TREATING AIRWAYS
Abstract
This relates to treating airways in a lung to decrease asthmatic
symptoms. The also includes steps of measuring a parameter of an
airway at a plurality of locations in a lung, identifying at least
one treatment site from at least one of the plurality of locations
based on the parameter, and applying energy to the treatment site
to reduce the ability of the site to narrow.
Inventors: |
DANEK; Christopher J.; (San
Carlos, CA) ; BIGGS; Michael; (Denver, CO) ;
LOOMAS; Bryan E.; (Los Gatos, CA) ; LAUFER; Michael
D.; (Menlo Park, CA) ; KAPLAN; Gary S.;
(Mountain View, CA) ; SHRINER; Kelly M.;
(Arlington, MA) ; WIZEMAN; William J.; (Mountain
View, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asthmatx, Inc. |
Sunnyvale |
CA |
US |
|
|
Family ID: |
37417920 |
Appl. No.: |
14/989147 |
Filed: |
January 6, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14171973 |
Feb 4, 2014 |
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14989147 |
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13557518 |
Jul 25, 2012 |
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14171973 |
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11398353 |
Apr 4, 2006 |
8251070 |
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13557518 |
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Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 5/08 20130101; A61B
2018/00898 20130101; A61B 2018/00214 20130101; A61B 5/0036
20180801; A61B 5/4878 20130101; A61B 2018/0022 20130101; A61B 18/14
20130101; A61B 18/1492 20130101; A61B 18/18 20130101; A61N 5/1001
20130101; A61B 1/00085 20130101; A61B 2018/1472 20130101; A61B
5/6858 20130101; A61B 2010/045 20130101; A61B 10/04 20130101; A61B
2018/00541 20130101; A61B 18/06 20130101; A61B 2017/00106 20130101;
A61B 2018/00875 20130101; A61B 5/053 20130101; A61B 5/0538
20130101; A61B 5/4519 20130101; A61B 5/6853 20130101; A61B
2018/00773 20130101; A61B 5/1076 20130101; A61B 2018/00244
20130101; A61B 5/4836 20130101; A61B 5/0809 20130101; A61B 2090/064
20160201; A61B 5/411 20130101; A61B 2017/00809 20130101; A61B
2090/061 20160201 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1-40. (canceled)
41. A method of treating a lung, the method comprising: inserting a
medical device into an airway of the lung, the medical device
including a catheter and a balloon disposed at a distal end of the
catheter, wherein a distalmost portion of the catheter extends
distally of a distalmost portion of the balloon; stimulating an
airway in the lung by introducing, via a port of the catheter, a
pharmacological agent into the airway to constrict the airway;
after stimulating the airway, measuring a constriction of the
airway via the balloon; delivering a fluid to the airway to
electrically couple an electrode to tissue surrounding the airway;
applying energy to the tissue, via the electrode and the fluid, to
damage nerves disposed radially outward of the airway to reduce the
ability of the lung to constrict in response to a stimulus;
conveying the fluid from the airway; and after applying energy,
determining an effectiveness of applying energy by determining
whether the lung has a reduced ability to produce at least one
symptom of reversible obstructive pulmonary disease.
42. The method of claim 41, wherein delivering the fluid to the
airway and applying energy to the tissue occur only if the measured
constriction is greater than a threshold value.
43. The method of claim 41, further including monitoring electrical
impedance of the tissue.
44. The method of claim 41, wherein applying energy to the tissue
includes applying RF energy to the tissue.
45. A method of treating a lung, the method comprising: inserting a
medical device into an airway of the lung, the medical device
including a catheter and a balloon disposed at a distal end of the
catheter, wherein a distalmost portion of the catheter extends
distally of a distalmost portion of the balloon; stimulating an
airway in the lung; after stimulating the airway, measuring a
parameter of the airway via the balloon; and applying energy to the
tissue to damage nerves disposed radially outward of the airway to
reduce the ability of the lung to constrict in response to a
stimulus.
46. The method of claim 45, further including delivering a fluid to
the airway to electrically couple an electrode to tissue
surrounding the airway.
47. The method of claim 46, wherein applying energy to the tissue
occurs through the electrode and the fluid.
48. The method of claim 46, further including conveying the fluid
from the airway.
49. The method of claim 45, wherein applying energy only occurs if
the measured parameter is greater than a threshold value.
50. The method of claim 49, wherein the measured parameter is a
contraction of the airway.
51. The method of claim 45, wherein, after applying energy, the
method further includes determining an effectiveness of applying
energy by determining whether the lung has a reduced ability to
produce at least one symptom of reversible obstructive pulmonary
disease.
52. The method of claim 45, wherein stimulating the airway includes
introducing a pharmacological agent into the airway.
53. A method of treating a lung, the method comprising: stimulating
an airway in the lung to constrict the airway; after stimulating
the airway, measuring a parameter of the airway via the balloon;
delivering a fluid to the airway to electrically couple an
electrode to tissue surrounding the airway; and applying energy to
the tissue, via the electrode and the fluid, to damage nerves
disposed radially outward of the airway to reduce the ability of
the lung to constrict in response to a stimulus.
54. The method of claim 53, further including conveying the fluid
from the airway.
55. The method of claim 53, further including, before stimulating
the airway, inserting a medical device into the airway, the medical
device including a catheter and a balloon disposed at a distal end
of the catheter, wherein a distalmost portion of the catheter
extends distally of a distalmost portion of the balloon, and
wherein the medical device provides the stimulation.
56. The method of claim 55, wherein stimulating the airway includes
introducing, via a port of the catheter, a pharmacological agent
into the airway.
57. The method of claim 55, wherein delivering the fluid and
applying energy to the tissue occur only if the measured parameter
is greater than a threshold value.
58. The method of claim 57, wherein the measured parameter is a
contractile force of the airway, and wherein the balloon measures
the contractile force.
59. The method of claim 53, further including after applying
energy, determining an effectiveness of applying energy by
determining whether the lung has a reduced ability to produce at
least one symptom of reversible obstructive pulmonary disease.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/171,973, filed Feb. 4, 2014, which is a
continuation of U.S. patent application Ser. No. 13/557,518, filed
Jul. 25, 2012, now abandoned, which is a continuation of U.S.
patent application Ser. No. 11/398,353, filed Apr. 4, 2006, now
U.S. Pat. No. 8,251,070, the entireties of each of which are
incorporated herein by reference. This application is related to
U.S. patent application Ser. No. 10/640,967, filed Aug. 13, 2003,
and U.S. patent application Ser. No. 09/535,856, filed Mar. 27,
2000, the entireties of each of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a method of treating a lung having
at least one symptom of reversible obstructive pulmonary disease,
and more particularly, methods of treating airways in a lung to
decrease asthmatic symptoms of the lung, by measuring a parameter
of an airway at a plurality of locations in a lung, identifying at
least one treatment site from at least one of the plurality of
locations based on the parameter; and applying energy to the
treatment site to reduce the ability of the site to narrow.
[0003] Reversible obstructive pulmonary disease includes asthma and
reversible aspects of chronic obstructive pulmonary disease (COPD).
Asthma is a disease in which (i) bronchoconstriction, (ii)
excessive mucus production, and (iii) inflammation and swelling of
airways occur, causing widespread but variable airflow obstruction
thereby making it difficult for the asthma sufferer to breathe.
Asthma is further characterized by acute episodes of airway
narrowing via contraction of hyper-responsive airway smooth
muscle.
[0004] The reversible aspects of COPD include excessive mucus
production and partial airway occlusion, airway narrowing secondary
to smooth muscle contraction, and bronchial wall edema and
inflation of the airways. Usually, there is a general increase in
bulk (hypertrophy) of the large bronchi and chronic inflammatory
changes in the small airways. Excessive amounts of mucus are found
in the airways and semisolid plugs of mucus may occlude some small
bronchi. Also, the small airways are narrowed and show inflammatory
changes.
[0005] In asthma, chronic inflammatory processes in the airway play
a central role in increasing the resistance to airflow within the
lungs. Many cells and cellular elements are involved in the
inflammatory process, particularly mast cells, eosinophils T
lymphocytes, neutrophils, epithelial cells, and even airway smooth
muscle itself. The reactions of these cells result in an associated
increase in sensitivity and hyper-responsiveness of the airway
smooth muscle cells lining the airways to particular stimuli.
[0006] The chronic nature of asthma can also lead to remodeling of
the airway wall (i.e., structural changes such as airway wall
thickening or chronic edema) that can further affect the function
of the airway wall and influence airway hyper-responsiveness.
Epithelial denudation exposes the underlying tissue to substances
that would not normally otherwise contact the underlying tissue,
further reinforcing the cycle of cellular damage and inflammatory
response.
[0007] In susceptible individuals, asthma symptoms include
recurrent episodes of shortness of breath (dyspnea), wheezing,
chest tightness, and cough. Currently, asthma is managed by a
combination of stimulus avoidance and pharmacology.
[0008] Stimulus avoidance is accomplished via systematic
identification and minimization of contact with each type of
stimuli. It may, however, be impractical and not always helpful to
avoid all potential stimuli.
[0009] Asthma is managed pharmacologically by: (1) long term
control through use of anti-inflammatories and long-acting
bronchodilators and (2) short term management of acute
exacerbations through use of short-acting bronchodilators. Both of
these approaches require repeated and regular use of the prescribed
drugs. High doses of corticosteroid anti-inflammatory drugs can
have serious side effects that require careful management. In
addition, some patients are resistant to steroid treatment. The
difficulty involved in patient compliance with pharmacologic
management and the difficulty of avoiding stimulus that triggers
asthma are common barriers to successful asthma management.
[0010] Asthma is a serious disease with growing numbers of
sufferers. Current management techniques are neither completely
successful nor free from side effects.
[0011] Accordingly, it would be desirable to provide an asthma
treatment which improves airflow without the need for patient
compliance.
[0012] In addition to the airways of the lungs, other body conduits
such as the esophagus, ureter, urethra, and coronary arteries, are
also subject to inflammation and periodic reversible spasms that
produce obstruction to flow.
SUMMARY OF THE INVENTION
[0013] The present invention relates to methods for treating a
lung, preferably having at least one symptom of reversible
obstructive pulmonary disease, comprising the steps of advancing a
treatment device into the lung and treating the lung with the
device to at least reduce the ability of the lung to produce at
least one symptom of reversible obstructive pulmonary disease and
to decrease the resistance to the flow of air through the lung.
[0014] A variation of the invention includes the method described
above further comprising the step of locating one or more treatment
sites within an airway of the lung, selecting at least one of the
treatment sites and treating at least one of the treatment sites
selected in the selecting step. The invention may further include
performing the steps while the lung is experiencing at least one
symptom of either natural or artificially induced reversible
obstructive pulmonary disease.
[0015] A further variation of the invention includes the method
described above and further includes the steps of testing the lung
for at least one pre-treatment pulmonary function value prior to
the treating step, and re-testing the lung for at least one
post-treatment pulmonary function value subsequent to the treating
step.
[0016] A further variation of the invention includes the method
described above further comprising identifying treatment sites
within the airway being highly susceptible to either airway
inflammation, airway constriction, excessive mucus secretion, or
any other symptom of reversible obstructive pulmonary disease.
[0017] Another variation of the invention includes the method
described above and the additional step of stimulating the lung to
produce at least one artificially induced symptom of reversible
obstructive pulmonary disease. The invention may further comprise
the step of evaluating the results of the stimulating step.
[0018] Another variation of the invention includes the method
described above where treating at least airway tissue within the
lung further comprises the step of determining the effect of the
treatment by visually observing the airway for blanching, or a
change in appearance, of airway tissue.
[0019] Another variation of the invention includes the method
described above where treating at least airway tissue at a
treatment site within the lung further comprises the step of
monitoring electrical impedance of tissue at one or more
points.
[0020] Another variation of the invention includes the method
described above where treating the lung includes sub-mucosal
treatment of at least airway tissue in the lung.
[0021] Another variation of the invention includes the method
described above where the treating step includes treating the lung
by depositing a radioactive substance in at least one treatment
site within the lung.
[0022] Another variation of the invention include the method
described above further including the step of scraping tissue from
a wall of an airway within the lung prior to the treating step. The
invention may further comprise depositing a substance on the
scraped wall of the airway.
[0023] Another variation of the invention includes the method
described above where the treating step uses a modality selected
from the group consisting of mechanical, chemical, radio frequency,
radioactive energy, heat, and ultrasound.
[0024] Another variation of the invention includes the method
described above further comprising pre-treating the lung to at
least reduce the ability of the lung to produce at least one
symptom of reversible obstructive pulmonary disease prior to the
treating step, where at least one parameter of the pre-treating
step is lesser than at least one parameter of the treating
step.
[0025] Another variation of the invention comprises the method
described above where the treating step includes separating the
treating step into stages to reduce the healing load on the lung.
The separating step may comprise treating different regions of the
lung at different times or dividing the number of treatment sites
into a plurality of groups of treatment sites and treating each
group at a different time.
[0026] Another variation of the invention includes the method
described above further comprising sensing movement of the lung and
repositioning the treatment device in response to said sensing
step.
[0027] Another variation of the invention includes the method
described above further comprising reducing the temperature of lung
tissue adjacent to a treatment site.
[0028] Another variation of the invention includes the method
described above further comprising the step of providing drug
therapy, exercise therapy, respiratory therapy, and/or education on
disease management techniques to further reduce the effects of
reversible obstructive pulmonary disease.
[0029] The invention further includes the method for reversing a
treatment to reduce the ability of the lung to produce at least one
symptom of reversible obstructive pulmonary disease comprising the
step of stimulating re-growth of smooth muscle tissue in the
lung.
[0030] The invention further includes the method of evaluating an
individual having reversible obstructive pulmonary disease as a
candidate for a procedure to reduce the ability of the individual's
lung to produce at least one reversible obstructive pulmonary
disease symptom by treating an airway within the lung of the
individual, the method comprising the steps of assessing the
pulmonary condition of the individual, comparing the pulmonary
condition to a corresponding predetermined state; and evaluating
the individual based upon the comparing step. The method may
additionally comprise the steps of performing pulmonary function
tests on the individual to obtain at least one pulmonary function
value, comparing the at least one pulmonary function value to a
corresponding predetermined pulmonary function value, and
evaluating the individual based upon the comparing step.
[0031] The invention further comprises a method of evaluating the
effectiveness of a procedure to reduce the ability of lung to
produce at least one symptom of reversible obstructive pulmonary
disease previously performed on an individual having reversible
obstructive pulmonary disease, the method comprising the steps of
assessing the pulmonary condition of the individual, comparing the
pulmonary condition to a corresponding predetermined state; and
evaluating the effectiveness of the procedure based upon the
comparing step. The method may additionally comprise the steps of
performing pulmonary function tests on the individual to obtain at
least one pulmonary function value, treating the lung to at least
reduce the ability of the lung to produce at least one symptom of
reversible obstructive pulmonary disease, performing post-procedure
pulmonary function tests on the individual to obtain at least one
post-procedure pulmonary function value; and comparing the
pulmonary function value with the post-procedure pulmonary function
value to determine the effect of the treating step.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The invention will now be described in greater detail with
reference to the various embodiments illustrated in the
accompanying drawings:
[0033] FIG. 1 is a cross sectional view of an airway in a healthy
lung.
[0034] FIG. 2 shows a section through a bronchiole having an airway
diameter smaller than that shown in FIG. 1.
[0035] FIG. 3 illustrates the airway of FIG. 1 in which the smooth
muscle 14 has hypertrophied and increased in thickness causing
reduction of the airway diameter.
[0036] FIG. 4A is a schematic view of the lungs being treated with
a treatment device as described herein.
[0037] FIG. 4B illustrates one example of a treatment system for
use with the methods described herein.
[0038] FIG. 4C illustrates another variation of a treatment system
that applies the treatment externally to the lungs.
[0039] FIG. 5 illustrates a map to aid in treatment of the
airways.
[0040] FIG. 6A illustrates a device that stimulates the airway into
contracting.
[0041] FIGS. 6B-6F illustrate various modes of measuring parameters
within the lungs to identify treatment sites.
[0042] FIG. 7 is a side view of a device extending out of an
endoscope/bronchoscope, where the device has an active distal end
for treating tissue using energy delivery.
[0043] FIG. 8 shows various features of a device allowing for low
force deployment of an energy element.
DETAILED DESCRIPTION
[0044] The invention relates to methods for improving airflow
through the airways of a lung having reversible obstructive
pulmonary disease. It is intended that the invention is applicable
to any aspect of reversible obstructive pulmonary disease,
including but not limited to asthma. One way of improving airflow
is to decrease the resistance to airflow within the lungs. There
are several approaches to reducing this resistance, including but
not limited to reducing the ability of the airway to contract,
increasing the airway diameter, reducing the inflammation of airway
tissues, and/or reducing the amount of mucus plugging of the
airway. Another approach to reducing resistance is to increase the
resting airway diameter of an airway such that any subsequent
narrowing will not reduce the airway to a diameter such that
obstruction to airflow is discernable by the patient. The present
invention includes advancing a treatment device into the lung and
treating the lung to at least reduce the ability of the lung to
produce at least one symptom of reversible obstructive pulmonary
disease. The following is a brief discussion of some causes of
increased resistance to airflow within the lungs and the inventive
treatment of the invention described herein. As such, the following
discussion is not intended to limit the aspects or objective of the
inventive method as the inventive method may cause physiological
changes not described below but such changes still contributing to
reducing or eliminating at least one of the symptoms of reversible
obstructive pulmonary disease.
Reducing the Ability of the Airway to Contract
[0045] The inventive treatment reduces the ability of the airways
to narrow or to reduce in diameter due to airway smooth muscle
contraction. The inventive treatment uses a modality of treatments
including, but not limited to the following: chemical, radio
frequency, radioactivity, heat, ultrasound, radiant, laser,
microwave, or mechanical energy (such as in the form of cutting,
punching, abrading, rubbing, or dilating). This treatment reduces
the ability of the smooth muscle to contract thereby lessening the
severity of an asthma attack. The reduction in the ability of the
smooth muscle to contract may be achieved by treating the smooth
muscle itself or by treating other tissues which in turn influence
smooth muscle contraction or the response of the airway to the
smooth muscle contraction. Treatment may also reduce airway
responsiveness or the tendency of the airway to narrow or to
constrict in response to a stimulus.
[0046] The amount of smooth muscle surrounding the airway can be
reduced by exposing the smooth muscle to energy which either kills
the muscle cells or prevents these cells from replicating. The
reduction in smooth muscle reduces the ability of the smooth muscle
to contract and to narrow the airway during a spasm. The reduction
in smooth muscle and surrounding tissue has the added potential
benefit of increasing the caliber or diameter of the airways, which
further reduces the resistance to airflow through the airways. In
addition to the use of debulking smooth muscle tissue to open up
the airways, the device used in the present invention may also
eliminate smooth muscle altogether by damaging or destroying the
muscle. The elimination of the smooth muscle prevents the
contraction or spasms of hyper-reactive airways of a patient having
reversible obstructive pulmonary disease. By doing so, the
elimination of the smooth muscle may reduce some symptoms of
reversible obstructive pulmonary disease.
[0047] The ability of the airway to contract can also be altered by
treatment of the smooth muscle in particular patterns. The smooth
muscle is arranged around the airways in a generally helical
pattern with pitch angles ranging from about -38 to about +38
degrees. Thus, the treatment of the smooth muscle in appropriate
patterns interrupts or cuts through the helical pattern of the
smooth muscle at a proper pitch and prevents the airway from
constricting. This procedure of patterned treatment application
eliminates contraction of the airways without completely
eradicating smooth muscle and other airway tissue. A pattern for
treatment may be chosen from a variety of patterns including
longitudinal or axial stripes, circumferential bands, helical
stripes, and the like as well as spot patterns having rectangular,
elliptical, circular or other shapes. The size, number, and spacing
of the treatment bands, stripes, or spots are chosen to provide a
desired clinical effect of reduced airway responsiveness while
limiting insult to the airway to a clinically acceptable level.
[0048] The patterned treatment of the tissues surrounding the
airways with energy provides various advantages. The careful
selection of the portion of the airway to be treated allows desired
results to be achieved while reducing the total healing load.
Patterned treatment can also achieve desired results with decreased
morbidity, preservation of epithelium, and preservation of a
continuous or near continuous ciliated inner surface of the airway
for mucociliary clearance. The pattern of treatment may also be
chosen to achieve desired results while limiting total treatment
area and/or the number of airways treated, thereby improving speed
and ease of treatment.
[0049] Application of energy to the tissue surrounding the airways
may also cause the DNA of the cells to become cross linked. The
treated cells with cross linked DNA are incapable of replicating.
Accordingly, over time, as the smooth muscle cells die, the total
thickness of smooth muscle decreases because of the inability of
the cells to replicate. The programmed cell death causing a
reduction in the volume of tissue is called apoptosis. This
treatment does not cause an immediate effect but causes shrinking
of the smooth muscle and opening of the airway over time and
substantially prevents re-growth. The application of energy to the
walls of the airway may also be used to cause a cross linking of
the DNA of the mucus gland cells thereby preventing them from
replicating and reducing excess mucus plugging or production over
time.
[0050] The ability of the airways to contract may also be reduced
by altering mechanical properties of the airway wall, such as by
increasing stiffness of the wall or by increasing parenchymal
tethering of the airway wall. Both of these methods increase the
strength of the airway wall and further oppose contraction and
narrowing of the airway.
[0051] There are several ways to increase the stiffness of the
airway wall. One way to increase stiffness is to induce fibrosis or
a wound healing response by causing trauma to the airway wall. The
trauma can be caused by delivery of therapeutic energy to the
tissue in the airway wall, by mechanical insult to the tissue, or
by chemically affecting the tissue. The energy is preferably
delivered in such a way that it minimizes or limits the
intra-luminal thickening that may occur.
[0052] Another way to increase the effective stiffness of the
airway wall is to alter the submucosal folding of the airway upon
narrowing. The mucosal layer includes the epithelium, its basement
membrane, and the lamina propria, a subepithelial collagen layer.
The submucosal layer may also play a role in airway folding. As an
airway narrows, its perimeter remains relatively constant, with the
mucosal layer folding upon itself. As the airway narrows further,
the mucosal folds mechanically interfere with each other,
effectively stiffening the airway. In asthmatic patients, the
number of folds is fewer and the size of the folds is larger, and
thus, the airway is free to narrow with less mechanical
interference of mucosal folds than in a healthy patient. Thus,
asthmatic patients have a decrease in airway stiffness and the
airways have less resistance to narrowing.
[0053] The mucosal folding in asthmatic patients can be improved by
treatment of the airway in a manner which encourages folding.
Preferably, a treatment will increase the number of folds and/or
decrease the size of the folds in the mucosal layer. For example,
treatment of the airway wall in a pattern such as longitudinal
stripes can encourage greater number of smaller mucosal folds and
increase airway stiffness.
[0054] The mucosal folding can also be increased by encouraging a
greater number of smaller folds by reducing the thickness of the
mucosa and/or submucosal layer. The decreased thickness of the
mucosa or submucosa may be achieved by application of energy which
either reduces the number of cells in the mucosa or submucosal
layer or which prevents replication of the cells in the mucosa or
submucosal layer. A thinner mucosa or submucosal layer will have an
increased tendency to fold and increased mechanical stiffening
caused by the folds.
[0055] Another way to reduce the ability of the airways to contract
is to improve parenchymal tethering. The parenchyma surrounds
airways and includes the alveolus and tissue connected to and
surrounding the outer portion of the airway wall. The parenchyma
includes the alveolus and tissue connected to and surrounding the
cartilage that supports the larger airways. In a healthy patient,
the parenchyma provides a tissue network which connects to and
helps to support the airway. Edema or accumulation of fluid in lung
tissue in patients with asthma or COPD is believed to decouple the
airway from the parenchyma reducing the restraining force of the
parenchyma which opposes airway constriction. Energy can be used to
treat the parenchyma to reduce edema and/or improve parenchymal
tethering.
[0056] In addition, the applied energy may be used to improve
connection between the airway smooth muscle and submucosal layer to
the surrounding cartilage, and to encourage wound healing, collagen
deposition, and/or fibrosis in the tissue surrounding the airway to
help support the airway and prevent airway contraction.
Increasing the Airway Diameter
[0057] Hypertrophy of smooth muscle, chronic inflammation of airway
tissues, and general thickening of all parts of the airway wall can
reduce the airway diameter in patients with reversible obstructive
pulmonary disease. Increasing the overall airway diameter using a
variety of techniques can improve the passage of air through the
airways. Application of energy to the airway smooth muscle of an
asthmatic patient can debulk or reduce the volume of smooth muscle.
This reduced volume of smooth muscle increases the airway diameter
for improved air exchange.
[0058] Reducing inflammation and edema of the tissue surrounding
the airway can also increase the diameter of an airway.
Inflammation and edema (accumulation of fluid) of the airway are
chronic features of asthma. The inflammation and edema can be
reduced by application of energy to stimulate wound healing and
regenerate normal tissue. Healing of the epithelium or sections of
the epithelium experiencing ongoing denudation and renewal allows
regeneration of healthy epithelium with less associated airway
inflammation. The less inflamed airway has an increased airway
diameter both at a resting state and in constriction. The wound
healing can also deposit collagen which improves parenchymal
tethering.
[0059] Inflammatory mediators released by tissue in the airway wall
may serve as a stimulus for airway smooth muscle contraction.
Therapy that reduces the production and release of inflammatory
mediator can reduce smooth muscle contraction, inflammation of the
airways, and edema. Examples of inflammatory mediators are
cytokines, chemokines, and histamine. The tissues which produce and
release inflammatory mediators include airway smooth muscle,
epithelium, and mast cells. Treatment of these structures with
energy can reduce the ability of the airway structures to produce
or release inflammatory mediators. The reduction in released
inflammatory mediators will reduce chronic inflammation, thereby
increasing the airway inner diameter, and may also reduce
hyper-responsiveness of the airway smooth muscle.
[0060] A further process for increasing the airway diameter is by
denervation. A resting tone of smooth muscle is nerve regulated by
release of catecholamines. Thus, by damaging or eliminating nerve
tissue in the airways the resting tone of the smooth muscle is
reduced, and the airway diameter is increased. Resting tone may
also be reduced by directly affecting the ability of smooth muscle
tissue to contract.
Reducing Plugging of the Airway
[0061] Excess mucus production and mucus plugging are common
problems during both acute asthma exacerbation and in chronic
asthma management. Excess mucus in the airways increases the
resistance to airflow through the airways by physically blocking
all or part of the airway. Excess mucus may also contribute to
increased numbers of leukocytes found in airways of asthmatic
patients by trapping leukocytes. Thus, excess mucus can increase
chronic inflammation of the airways.
[0062] One type of asthma therapy involves treatment of the airways
with energy to target and reduce the amount of mucus producing
cells, ducts, and glands and to reduce the effectiveness of the
remaining mucus producing cells and glands. The treatment can
eliminate all or a portion of the mucus producing cells, ducts, and
glands, can prevent the cells from replicating or can inhibit their
ability to secrete mucus. This treatment will have both chronic
benefits in increasing airflow through the airways and will lessen
the severity of acute exacerbation of the symptoms of reversible
obstructive pulmonary disease.
Application of Treatment
[0063] The following illustrations are examples of the invention
described herein. It is contemplated that combinations of aspects
of specific embodiments or combinations of the specific embodiments
themselves are within the scope of this disclosure.
[0064] FIGS. 1 and 2 illustrate cross sections of two different
airways in a healthy patient. The airway of FIG. 1 is a medium
sized bronchus having an airway diameter D1 of about 3 mm. FIG. 2
shows a section through a bronchiole having an airway diameter D2
of about 1.5 mm. Each airway includes a folded inner surface or
epithelium 10 surrounded by stroma 12 and smooth muscle tissue 14.
The larger airways including the bronchus shown in FIG. 1 also have
mucous glands 16 and cartilage 18 surrounding the smooth muscle
tissue 14. Nerve fibers 20 and blood vessels 24 also surround the
airway.
[0065] FIG. 3 illustrates the bronchus of FIG. 1 in which the
smooth muscle 14 has hypertrophied and increased in thickness
causing the airway diameter to be reduced from the diameter D1 to a
diameter D3.
[0066] FIG. 4A is a schematic side view of the lungs being treated
with a treatment device 38 according to the present invention. The
treatment device 100 is an elongated member for treating tissue at
a treatment site 34 within a lung. Although the invention discusses
treatment of tissue at the airway wall surface it is also intended
that the invention include treatment below an epithelial layer of
the lung tissue. The invention may also rely on the use of an
imaging device 36 to enable the identification of at least one
treatments site from the plurality of possible treatment site
locations. The imaging device may employ radiographic visualization
such as fluoroscopy or other external visualization means such as
computer aided tomography (CT), magnetic resonance imaging (MRI),
positron emission tomography (PET), optical coherence tomography,
or ultrasonic imaging. The imaging device may be external as shown.
Alternatively, the imaging device may have a component that is
affixed to the treatment system 32 or otherwise is inserted in to
the body.
[0067] FIG. 4B represents one example of a treatment system 32
according to the present invention. In this variation, the system
32 delivers therapeutic energy to tissue of a patient via a device
100. Variations of devices are described in U.S. application Ser.
Nos. 11/255,796 and 11/256,295 both filed Oct. 21, 2005 and the
entirety of each of which is incorporated by reference.
[0068] FIG. 4B shows a schematic diagram of one example of a system
32 for delivering therapeutic energy to tissue of a patient for use
with the device described herein. The illustrated variation shows,
the system 32 having a power supply (e.g., consisting of an energy
generator 112, a controller 114 coupled to the energy generator, a
user interface surface 116 in communication with the controller
114). It is noted that the device may be used with a variety of
systems (having the same or different components). For example,
although variations of the device shall be described as RF energy
delivery devices, variations of the device may include resistive
heating systems, infrared heating elements, microwave energy
systems, focused ultrasound, cryo-ablation, or any other energy
deliver system. It is noted that the devices described should have
sufficient length to access the tissue targeted for treatment. For
example, it is presently believed necessary to treat airways as
small as 3 mm in diameter to treat enough airways for the patient
to benefit from the described treatment (however, it is noted that
the invention is not limited to any particular size of airways and
airways smaller than 3 mm may be treated). Accordingly, devices for
treating the lungs must be sufficiently long to reach deep enough
into the lungs to treat these airways. Accordingly, the length of
the sheath/shaft of the device that is designed for use in the
lungs should preferably be between 1.5-3 ft long in order to reach
the targeted airways.
[0069] The particular system 32 depicted in FIG. 4B is one having a
user interface as well as safety algorithms that are useful for the
asthma treatment discussed above. Addition information on such a
system may be found in U.S. Provisional application Nos.
60/674,106, and 60/673,876 both filed Apr. 21, 2005 the entirety of
each of which is incorporated by reference herein.
[0070] Referring again to FIG. 4B, a variation of a device 100
described herein includes a flexible sheath 202, an elongate shaft
204 (in this example, the shaft extends out from the distal end of
the sheath 202), and a handle or other operator interface 206
(optional) secured to a proximal end of the sheath 202. The distal
portion of the device 100 includes an energy transfer element 208
(e.g., an electrode, a basket electrode, a resistive heating
element, cryoprobe, etc.). Additionally, the device includes a
connector 210 common to such energy delivery devices. The connector
210 may be integral to the end of a cable 212 as shown, or the
connector 210 may be fitted to receive a separate cable 212. In any
case, the device is configured for attachment to the power supply
via some type connector 210. The elongate portions of the device
202 and 204 may also be configured and sized to permit passage
through the working lumen of a commercially available bronchoscope
or endoscope. As discussed herein, the device is often used within
an endoscope, bronchoscope or similar device. However, the device
may also be advanced into the body with or without a steerable
catheter, in a minimally invasive procedure or in an open surgical
procedure, and with or without the guidance of various vision or
imaging systems.
[0071] FIG. 4B also illustrates additional components used in
variations of the system. Although the depicted systems are shown
as RF type energy delivery systems, it is noted that the invention
is not limited as such. Other energy delivery configurations
contemplated may include or not require some of the elements
described below. The power supply (usually the user interface
portion 116) shall have connections 120, 128, 130 for the device
100, return electrode 124 (if the system 32 employs a monopolor RF
configuration), and actuation pedal(s) 126 (optional). The power
supply and controller may also be configured to deliver RF energy
to an energy transfer element configured for bipolar RF energy
delivery. The user interface 116 may also include visual prompts
132, 160, 168, 174 for user feedback regarding setup or operation
of the system. The user interface 116 may also employ graphical
representations of components of the system, audio tone generators,
as well as other features to assist the user with system use.
[0072] In many variations of the system, the controller 114
includes a processor 122 that is generally configured to accept
information from the system and system components, and process the
information according to various algorithms to produce control
signals for controlling the energy generator 112. The processor 122
may also accept information from the system 110 and system
components, process the information according to various algorithms
and produce information signals that may be directed to the visual
indicators, digital display or audio tone generator of the user
interface in order to inform the user of the system status,
component status, procedure status or any other useful information
that is being monitored by the system. The processor 122 of the
controller 114 may be digital IC processor, analog processor or any
other suitable logic or control system that carries out the control
algorithms.
[0073] In one variation of the system shown in FIG. 4B, the RF
generator 112 generates RF energy at a frequency of about 400 kHz
to about 500 kHz in with a wattage output sufficient to maintain a
target tissue temperature of about 60 degrees C. to about 80
degrees C., specifically, about 60 degrees C. to about 70 degrees
C. (when measuring at a surface of the electrode). The duration of
the activation state for an embodiment of a single treatment cycle
may be about 1 seconds to about 15 seconds, specifically, about 8
seconds to about 12 seconds. Alternatively, the duration of the
activation state of the RF generator may also be set to not more
than the duration required to deliver about 150 Joules of energy to
the target tissue, specifically, not more than the duration
required to deliver about 125 Joules of RF energy to target
tissue.
[0074] Additional examples of devices for use with the methods of
this invention are found in the following U.S. patent application
Ser. Nos. 09/095,323 and 09/436,455; U.S. Pat. Nos. 6,488,673 and
6,411,852. The entirety of each of the aforementioned applications
is incorporated by reference herein.
[0075] FIG. 4C represents another schematic side view of lungs
being treated with a treatment device 100 according to the present
invention. In this variation, the treatment device 100 and system
32 are external to the lungs and/or body but still applies energy
to within the lungs. For example, such a treatment may use a high
frequency ultrasound (commonly referred to as HIFU). As discussed
above, the invention may also rely on the use of an imaging device
36.
[0076] The treatment of an airway with the treatment device may
involve placing a visualization system such as an endoscope or
bronchoscope into the airways. The treatment device is then
inserted through or next to the bronchoscope or endoscope while
visualizing the airways. Alternatively, the visualization system
may be built directly into the treatment device using fiber optic
imaging and lenses or a CCD and lens arranged at the distal portion
of the treatment device. The treatment device may also be
positioned using radiographic visualization such as fluoroscopy or
other external visualization means. The treatment device which has
been positioned with a distal end within an airway to be treated is
energized so that energy is applied to the tissue of the airway
walls in a desired pattern and intensity. The distal end of the
treatment device may be moved through the airway in a uniform
painting like motion to expose the entire length of an airway to be
treated to the energy. The treatment device may be passed axially
along the airway one or more times to achieve adequate treatment.
The "painting-like" motion used to expose the entire length of an
airway to the energy may be performed by moving the entire
treatment device from the proximal end either manually or by motor.
Alternatively, segments, stripes, rings or other treatment patterns
may be used.
[0077] According to one variation of the invention, the energy is
transferred to or from an airway wall in the opening region of the
airway, preferably within a length of approximately two times the
airway diameter or less, and to wall regions of airways distal to
bifurcations and side branches, preferably within a distance of
approximately twice the airway diameter or less. The invention may
also be used to treat long segments of un-bifurcated airway.
[0078] The invention includes a method of advancing a treatment
device into a lung and treating the lung with the device to, at
least, reduce the ability of the lung to produce at least one
symptom of reversible obstructive pulmonary disease. It is
contemplated that the treatment may reduce all of the symptoms of
reversible obstructive disease. Alternatively, the treatment may be
selected to address specific symptoms of the disease. It is also
intended that the treatment of the lung may sufficiently reduce the
symptoms of reversible obstructive pulmonary disease such that the
patient is able to function as those free from the disease.
Alternatively, the treatment may be such that the symptoms are
reduced to allow the patient to more easily manage the disease. It
is also intended that the effects of the treatment may be either
long term or short term with repeating treatment necessary to
suppress the symptoms.
[0079] The methods of the invention described herein may be
performed while the lung is experiencing natural symptoms of
reversible obstructive pulmonary disease. One such example is where
an individual, experiencing an asthma attack, or acute exacerbation
of asthma or COPD, undergoes treatment to improve the individual's
ability to breath. In such a case, the treatment, called `rescue,`
seeks to provide immediate relief for the patient.
[0080] The method may also include the steps of locating one or
more treatment sites within an airway of the lung, selecting one of
the treatment sites from the locating step and treating at least
one of the selected treatment sites. As mentioned above, these
steps may be, but are not necessarily, performed while the lung is
experiencing symptoms of reversible obstructive pulmonary
disease.
[0081] The invention may further comprise the step of stimulating
the lung to produce at least one artificially induced symptom of
reversible obstructive pulmonary disease. For example, stimulation
of the lung would preferably increase the resistance to airflow
within the lung, constrict airways within the lung,
inflame/irritate airway tissues, increase edema and/or increase the
amount of mucus plugging of the airway. Stimulation of the lung may
occur at any point during the procedure or before the procedure.
For example, the lung may be stimulated either prior to or after,
the step of locating a treatment site. If the lung is stimulated
prior to the step of locating a treatment site, the reaction of the
stimulated tissue within the lung may be useful in determining
which locations are to be selected as treatment sites. The lung
tissue or airway tissue within the lung may be stimulated by a
variety of methods including but not limited to pharmacological
stimulation, (e.g., histamine, methacholine, or other
bronchoconstricting agents, etc.), electrical stimulation,
mechanical stimulation, or any other stimuli causing obstructive
pulmonary symptoms. For example, electrical stimulation may
comprise exposing airway tissue to electrical field stimulation. An
example of such parameters include 15 VDC, 0.5 ms pulses, 0.5-16
Hz, and 70 VDC, 2-3 ms pulses, 20 HZ.
[0082] The locating step described above may be performed using a
non-invasive imaging technique, including but not limited to, a
bronchogram, magnetic resonance imaging, computed tomography,
radiography (e.g., x-ray), and ventilation perfusion scans.
[0083] The invention further includes the steps of testing the lung
for at least one pre-treatment pulmonary function value prior to
treating the lung with the device. After the lung is treated, the
lung is re-tested for at least one post-treatment pulmonary
function value. Naturally, the two pulmonary function values may be
compared to estimate the effect of the treatment. The invention may
also include treating additional sites in the lung after the
re-testing step to at least reduce the effect of at least one
symptom of reversible obstructive pulmonary disease. The invention
may also include stimulating the lung to produce at least one
artificially induced symptom of reversible obstructive pulmonary
disease. As mentioned above, the stimulation of the lung may occur
at any point during, or prior to, the procedure. For example,
stimulation of the lung may occur prior to the step of testing the
lung for pre-treatment pulmonary values. In this case, the values
would be determinative of pulmonary function values of a lung
experiencing symptoms of reversible obstructive pulmonary disease.
Accordingly, the objective is to treat the lung until acceptable
pulmonary function values are obtained. One benefit of such a
procedure is that the effect of the treatment on the patient is
more readily observed as compared to the situation where a patient,
having previously been treated, must wait for an attack of
reversible obstructive pulmonary disease to determine the efficacy
of the treatment.
[0084] Pulmonary function values are well known in the art. The
following is an example of pulmonary function values that may be
used. Other pulmonary function values, or combinations thereof, are
intended to be within the scope of this invention. The values
include, but are not limited to, FEV (forced expiratory volume),
FVC (forced vital capacity), FEF (forced expiratory flow), Vmax
(maximum flow), PEFR (peak expiratory flow rate), FRC (functional
residual capacity), RV (residual volume), TLC (total lung
capacity).
[0085] FEV measures the volume of air exhaled over a pre-determined
period of time by a forced expiration immediately after a full
inspiration. FVC measures the total volume of air exhaled
immediately after a full inspiration. Forced expiratory flow
measures the volume of air exhaled during a FVC divided by the time
in seconds. Vmax is the maximum flow measured during FVC. PEFR
measures the maximum flow rate during a forced exhale starting from
full inspiration. RV is the volume of air remaining in the lungs
after a full expiration.
[0086] The locating step described above may also comprise
identifying treatment sites within the airway being susceptible to
a symptom of reversible obstructive pulmonary disease. For example,
symptoms may include, but are not limited to, airway inflammation,
airway constriction, excessive mucous secretion, or any other
asthmatic symptom. Stimulation of the lung to produce symptoms of
reversible obstructive pulmonary disease may assist in identifying
ideal treatment sites.
[0087] As noted above, the method of the present invention may
include stimulating the lung to produce at least one artificially
induced symptom of reversible obstructive pulmonary disease and
further include the step of evaluating the result of stimulation of
the lung. For example, the evaluating step may include visually
evaluating the effect of the stimulating step on the airway using a
bronchoscope with a visualization system or by non-invasive imaging
techniques, such as those describe herein. The evaluating step may
include measuring pressure changes in the airway before and after
the stimulating step. Pressure may be measured globally (e.g.,
within the entire lung), or locally (e.g., within a specific
section of the lung such as an airway or alveolar sac.) Also, the
evaluating step may comprise measuring the electrical properties of
the tissue before and after the stimulating step. The invention may
also include evaluating the results of the stimulating step by
combining any of the methods previously mentioned. Also, the
invention may further comprise the step of selecting at least one
treatment parameter based upon the results of the evaluating step.
Such treatment parameters may include, but are not limited to,
duration of treatment, intensity of treatment, temperature, amount
of tissue treated, depth of treatment, etc.
[0088] The method may also include the step of determining the
effect of the treatment by visually observing lung, airway or other
such tissue for blanching of the tissue. The term "blanching" is
intended to include any physical change in tissue that is usually,
but not necessarily, accompanied by a change in the color of the
tissue. One example of such blanching is where the tissue turns to
a whitish color after the treatment of application of energy.
[0089] The invention may also include the step of monitoring
impedance across a treated area of tissue within the lung.
Measuring impedance may be performed in cases of monopolar or
bipolar energy delivery devices. Additionally, impedance may be
monitored at more than one site within the lungs. The measuring of
impedance may be, but is not necessarily, performed by the same
electrodes used to deliver the energy treatment to the tissue.
Furthermore, the invention includes adjusting the treatment
parameters based upon the monitoring of the change in impedance
after the treatment step. For example, as the energy treatment
affects the properties of the treated tissue, measuring changes in
impedance may provide information useful in adjusting treatment
parameters to obtain a desired result.
[0090] Another aspect of the invention includes advancing a
treatment device into the lung and treating lung tissue to at least
reduce the ability of the lung to produce at least one symptom of
reversible obstructive pulmonary disease and further comprising the
step of sub-mucosal sensing of the treatment to the lung tissue.
The sub-mucosal sensing may be invasive such as when using a probe
equipped to monitor temperature, impedance, and/or blood flow. Or,
the sub-mucosal sensing may be non-invasive in such cases as
infra-red sensing.
[0091] The invention may also include using the treatment device to
deposit radioactive substances at select treatment sites within the
lung. The radioactive substances, including, but not limited to
Iridium (e.g. 192Ir.) either treat the lung tissue over time or
provide treatment upon being deposited.
[0092] The invention also includes scraping epithelial tissue from
the wall of an airway within the lung prior to advancing a
treatment device into the lung to treat the lung tissue. The
removal of the epithelial tissue allows the device to treat the
walls of an airway more effectively. The invention further
comprises the step of depositing a substance on the scraped wall of
the airway after the device treats the airway wall. The substance
may include epithelial tissue, collagen, growth factors, or any
other bio-compatible tissue or substance, which promotes healing,
prevents infection, and/or assists in the clearing of mucus.
Alternatively, the treatment may comprise the act of scraping
epithelial tissue to induce yield the desired response.
[0093] The invention includes using the treating device to
pre-treat the lung to at least reduce the ability of the lung to
produce at least one symptom of reversible obstructive pulmonary
disease prior to the treating step. At least one of the parameters
of the pre-treating step may differ than one of the parameters of
the treating step. Such parameters may include time, temperature,
amount of tissue over which treatment is applied, amount of energy
applied, depth of treatment, etc.
[0094] The invention may also include advancing the treatment
device into the lung and treating the lung tissue in separate
stages. One of the benefits of dividing the treating step into
separate stages is that the healing load of the patient is
lessened. Dividing of the treating step may be accomplished by
treating different regions of the lung at different times. Or, the
total number of treatment sites may be divided into a plurality of
groups of treatment sites, where each group of treatment sites is
treated at a different time. The amount of time between treatments
may be chosen such that the healing load placed on the lungs is
minimized.
[0095] The invention may also include advancing a treatment device
into the lung, treating the lung with the device and sensing
movement of the lung to reposition the treatment device in response
to the movement. This sensing step accounts for the tidal motion of
the lung during breathing cycles or other movement. Taking into
account the tidal motion allows improved accuracy in repositioning
of the device at a desired target.
[0096] The invention may also include the additional step of
reducing or stabilizing the temperature of lung tissue near to a
treatment site. This may be accomplished for example, by injecting
a cold fluid into lung parenchyma or into the airway being treated,
where the airway is proximal, distal, or circumferentially adjacent
to the treatment site. The fluid may be sterile normal saline, or
any other bin-compatible fluid. The fluid may be injected into
treatment regions within the lung while other regions of the lung
normally ventilated by gas. Or, the fluid may be oxygenated to
eliminate the need for alternate ventilation of the lung. Upon
achieving the desired reduction or stabilization of temperature the
fluid may be removed from the lungs. In the case where a gas is
used to reduce temperature, the gas may be removed from the lung or
allowed to be naturally exhaled. One benefit of reducing or
stabilizing the temperature of the lung may be to prevent excessive
destruction of the tissue, or to prevent destruction of certain
types of tissue such as the epithelium, or to reduce the systemic
healing load upon the patient's lung.
[0097] Also contemplated as within the scope of the invention is
the additional step of providing therapy to further reduce the
effects of reversible obstructive pulmonary disease or which aids
the healing process after such treatment. Some examples of therapy
include, drug therapy, exercise therapy, and respiratory therapy.
The invention further includes providing education on reversible
obstructive pulmonary disease management techniques to further
reduce the effects of the disease. For example, such techniques may
be instruction on lifestyle changes, self-monitoring techniques to
assess the state of the disease, and/or medication compliance
education.
[0098] There may be occurrences where it is necessary to reverse
the effects of the treatment described herein. Accordingly, the
invention further includes a method for reversing a treatment to
reduce the ability of the lung to produce at least one symptom of
reversible obstructive pulmonary disease comprising the step of
stimulating re-growth of smooth muscle tissue. The re-stimulation
of the muscle may be accomplished by the use of
electro-stimulation, exercising of the muscle and/or drug
therapy.
[0099] The invention further includes methods of evaluating
individuals having reversible obstructive pulmonary disease, or a
symptom thereof, as a candidate for a procedure to reduce the
ability of the individual's lung to produce at least one symptom of
reversible obstructive pulmonary disease. The method comprises the
steps of assessing the pulmonary condition of the individual,
comparing the pulmonary condition to a corresponding pre-determined
state, and evaluating the individual as a candidate based upon the
comparison.
[0100] In assessing the pulmonary condition, the method may
comprise the steps of performing pulmonary function tests on the
individual to obtain a pulmonary function value which is compared
to a predetermined value. Examples of pre-determined values are
found above.
[0101] The method of evaluating may further include the step of
determining how the individual's tissue will react to treatment
allowing the treatment to be tailored to the expected tissue
response.
[0102] The method of evaluating may further comprises the step of
pulmonary function testing using a gas, a mixture of gases, or a
composition of several mixtures of gases to ventilate the lung. The
difference in properties of the gases may aid in the pulmonary
function testing. For example, comparison of one or more pulmonary
function test values that are obtained with the patient breathing
gas mixtures of varying densities may help to diagnose lung
function. Examples of such mixtures include air, at standard
atmospheric conditions, and a mixture of helium and oxygen.
Additional examples of pulmonary testing include tests that measure
capability and evenness of ventilation given diffusion of special
gas mixtures. Other examples of gases used in the described tests,
include but are not limited to, nitrogen, carbon monoxide, carbon
dioxide, and a range of inert gases.
[0103] The invention may also comprise the step of stimulating the
lung to produce at least one artificially induced symptom of
reversible obstructive pulmonary disease. Stimulating the symptoms
of the disease in an individual allows the individual to be
evaluated as the individual experiences the symptoms thereby
allowing appropriate adjustment of the treatment.
[0104] The method of evaluating may also comprise the step of
obtaining clinical information from the individual and accounting
for the clinical information for treatment.
[0105] The method may further comprise the selection of a patient
for treatment based upon a classification of the subtype of the
patient's disease. For example, in asthma there are a number of
ways to classify the disease state. One such method is the
assessment of the severity of the disease. An example of a
classification scheme by severity is found in the NHLBI Expert
Panel 2 Guidelines for the Diagnosis and Treatment of Asthma.
Another selection method may include selecting a patient by the
type of trigger that induces the exacerbation. Such triggers may be
classified further by comparing allergic versus non-allergic
triggers. For instance, an exercise induced bronchospasm (EIB) is
an example of a non-allergenic trigger. The allergic sub-type may
be further classified according to specific triggers (e.g., dust
mites, animal dander, etc.). Another classification of the allergic
sub-type may be according to characteristic features of the immune
system response such as levels of IgE (a class of antibodies that
function in allergic reactions, also called immunoglobulin). Yet
another classification of allergic sub-types may be according to
the expression of genes controlling certain interleukins (e.g.,
IL-4, IL-5, etc.) which have been shown to play a key role in
certain types of asthma.
[0106] The invention further comprises methods to determine the
completion of the procedure and the effectiveness of the reduction
in the lung's ability to produce at least one symptom of reversible
obstructive pulmonary disease. This variation of the invention
comprises assessing the pulmonary condition of the individual,
comparing the pulmonary condition to a corresponding predetermined
state, and evaluating the effectiveness of the procedure based on
the comparison. The invention may also comprise the steps of
performing pulmonary function tests on the individual to obtain at
least one pulmonary function value, treating the lung to at least
reduce the ability of the lung to produce at least one symptom of
reversible obstructive pulmonary disease, performing a
post-procedure pulmonary function tests on the individual to obtain
at least one post pulmonary function value and comparing the two
values.
[0107] This variation of the invention comprises obtaining clinical
information, evaluating the clinical information with the results
of the test to determine the effectiveness of the procedure.
Furthermore, the variation may include stimulating the lung to
produce a symptom of reversible obstructive pulmonary disease,
assessing the pulmonary condition of the patient, then repeating
the stimulation before the post-procedure pulmonary therapy. These
steps allow comparison of the lung function when it is experiencing
symptoms of reversible obstructive pulmonary disease, before and
after the treatment, thereby allowing for an assessment of the
improved efficiency of the lung during an attack of the
disease.
[0108] The medical practitioners performing the treatments
described herein may wish to treat a limited number of sites in the
lung to produce acceptable results in lessening the severity of
asthmatic or reversible obstructive pulmonary disease symptoms. For
example, if a patient requires an increasing amount of medication
(e.g., sedatives or anesthesia) to remain under continued control
for performance of the procedure, then a medical practitioner may
limit the procedure time rather than risk overmedicating the
patient. As a result, rather than treating the patient continuously
to complete the procedure, the practitioner may plan to break the
procedure in two or more sessions. Subsequently, increasing the
number of sessions poses additional consequences on the part of the
patient in cost, the residual effects of any medication, adverse
effects of the non-therapeutic portion of the procedure, etc.
[0109] Accordingly, the invention includes methods of treating
airways in a lung to decrease asthmatic symptoms. The methods
include measuring a parameter of an airway at a plurality of
locations in a lung, identifying at least one treatment site from
at least one of the plurality of locations based on the parameter,
and applying energy to the treatment site to reduce the ability of
the site to narrow.
[0110] Identification of the treatment sites may comprise comparing
the parameter to known or studied parameters and selecting those
sites that meet or exceed specific criteria. Alternatively, or in
combination, identification of treatment sites may comprise
selecting the sites with the most significant parameters, or
delivering a treatment specifically tailored to the parameters
measured at each individual site. For example, if the parameter
comprises measuring contractile force or the amount of contraction,
then sites having the highest quantitative parameters may be
selected as treatment sites. In another variation, the medical
practitioner may simply rank the parameters in a desired order of
value and treat those sites that are believed to provide the most
benefit. For example, the medical practitioner may chose to treat
the top 10% of sites having the most contraction, smooth muscle
tissue, or other parameters as described herein. It is also
contemplated that the diametrical size of the airway or the length
of the airway segment may be correlated to the ability for that
site to narrow. For example, when measuring a narrowed airway
diameter relative to its natural diameter, the percentage change
for a large diameter airway may be different than a percentage
change for a smaller airway. In such a case, the medical
practitioner may measure the airway diameter at each site for
determining the course of treatment. In other words, the
practitioner may deliver treatment to specific sites that meet
certain criteria (e.g., sites having a certain diameter).
Alternatively, or in combination, the practitioner may delivery
treatment specifically tailored to each individual site based on a
characteristic of the site (e.g., its diameter). For example, when
delivering energy, the practitioner could deliver more energy to
larger diameter airway, and less energy to smaller diameter airways
(or vice versa).
[0111] In those cases where more than one treatment site is
identified, the method may include the act of treating the new
treatment site.
[0112] The method may also include correlating the treatment sites
to a map 90, as shown in FIG. 5, the map may provide a graphical
representation of a bronchial tree. As shown, the various
bronchioles 92 decrease in size and have many branches 96 as they
extend into the right and left bronchi 94. Accordingly, an
efficient treatment may require identification of potential
treatment sites, treated sites, and other areas of the bronchial
tree.
[0113] This mapping may be performed for a variety of reasons. For
example, prior to treatment, the correlation may identify general
areas for treatment by the medical practitioner. Once the area is
treated, the map may then be marked to indicate a completed
treatment. The treatment plan provided by the map should allow the
medical practitioner a guide so that it is possible to treat less
than all of the lungs. The treatment plan or map also may assist in
avoiding double treatment of a particular treatment site. It is
contemplated that the map 90 may be an actual chart, whether in
tangible form or electronic form. Furthermore, the map may be
incorporated into the treatment system 32 or the user interface 116
as discussed above. It is also contemplated that the map may be a
three dimensional computer model, wherein the position of completed
treatment sites are recorded by storing the spatial coordinates of
these sites as each treatment is completed. As subsequent
treatments are made, the user may compare the current position of
the catheter to the map, which will aid in determining which site
to treat next.
[0114] The parameters to be measured in accordance with the methods
described herein may be any parameter that is an indicator of or
associated with symptoms of asthma. For example, the parameter may
be a measure of pulmonary function values (see above), a measure of
the contractile force at which the airway contracts, a thickness or
amount of the airway smooth muscle at a particular location,
eosinophil counts near or at the actual or potential treatment
site, degree of airflow within the airway, degree of contraction of
the airway during an asthma episode or after stimulation of the
airway, metabolic rate to assess the presence of smooth muscle,
electrical impedance to assess the nature of the airway tissue,
and/or degree of wheezing at a particular location, etc. Other
parameters indicative of asthma or a lack of airflow due to
asthmatic symptoms are also intended to be within the scope of this
disclosure.
[0115] Methods of the present invention include first stimulating
the airway and then subsequently measuring the parameter. The
stimulation may be performed electrically (such as by placing a
device within the airway and stimulating using the settings
described above). Alternatively, or in combination, the stimulation
may be artificially induced using an agent, such as methacholine.
For example, as shown in FIG. 6A, a device 150 may deliver the
agent 152 into the airway 2.
[0116] Once the airway contracts, the contraction may be measured
or assessed. Although not shown, the contraction may be measured or
assessed without making contact with the airway wall (e.g.,
visually with a retical; or optically, via a camera).
Alternatively, or in combination, as shown in FIG. 6B, a
contraction measurement device 154 may be placed against the airway
(either prior or during contraction) and expanded to measure a
natural state of the airway. The contraction measurement device 154
then transmits information regarding the contraction of the airway
using, for example, strain gauges 156 placed on moveable arms of
the device. The contraction measurement device 154 may also deliver
an agent to cause contraction of the airways. In this manner, the
device 154 will be in place while the airway contracts.
[0117] FIG. 6C illustrates another variation where a balloon
catheter 158 measures contraction of the airway. As the airway
constricts, the balloon 160 increases in pressure. The pressure may
then be characterized to determine the degree of contractile force
of the airway. It should be noted that the balloon catheter 158 may
also include fluid delivery ports to deliver an agent or have
electrodes to induce the contraction. Other examples of devices
that may be used to measure contraction of the airways are devices
that measure the airway diameter mechanically or optically.
[0118] In another variation as shown in FIG. 6D, a device 162
(e.g., an ultrasound balloon catheter, a non-balloon ultrasound
catheter, a catheter (balloon or non-balloon) that is equipped to
measure impedance, etc.), may be expanded within the airway to
measure the thickness of the adjacent airway smooth muscle 14.
Alternatively, as described above, the measurement of the airway
smooth muscle 14 may be achieved using the external imaging
equipment 36 described above.
[0119] Another method of measuring parameters of an airway for
identifying treatment sites comprises measuring eosinophil counts
at the location. Eosinophils are white blood cells active in
allergic diseases, parasitic infections, and other disorders. It is
believed that cosinophils correlate to the amount of inflammation
in an airway. FIG. 6E shows one way of obtaining an cosinophils
count at a location in the lung. As shown, a device 164 advances a
needle 166 within the airway to collect the eosinophils. Next,
standard techniques are employed to measure the particular
eosinophil count at the site.
[0120] FIG. 6F illustrates another variation of the invention where
a device 168 measures airflow airflow at a location or near to a
location for treatment. The device 168 may be a hot-wire
amenometer, where the airflow causes the heated wire 170 to cool
and the rate of cooling of the wire provides information regarding
the airflow.
[0121] In additional variations of the method, the medical
practitioner may deliver hyperpolarized helium or a radioactive
isotope to aid in the imaging of the airways. External imaging, as
shown FIGS. 4A and 4C may be used to assess ventilation in the lung
and select the areas that constrict as treatment sites.
[0122] Alternatively, the external imaging may take a first image
of the airways. Next, an agent is applied (either locally,
systemically, or limited to a particular lobe) to induce
contraction of the airways. The medical practitioner may then
obtain a second image of the airways for comparison with the first
to determine contraction of the airways.
[0123] In another variation of the invention, the parameter
comprises assessing a metabolic rate at the location. If the
measurement of the metabolic rate indicates the presence of a
significant amount of smooth muscle tissue, then the area may be
designated as a treatment site. The metabolic rate may be measured
over a treatment site or over an area of the airways (e.g., a
particular lobe or a section thereof.) The measurement of the
metabolic rate may be performed using standard measuring
techniques. For example, the device may deliver cool air to the
treatment site and then measure the rate at which the tissue
temperature returns to the original baseline temperature, thereby
providing a measurement of the calories used to bring the tissue
back to the baseline temperature. This would, in turn, provide a
measure of the responsiveness of the smooth muscle tissue because
more reactive or responsive tissue may correlate to a higher
metabolic rate.
[0124] FIG. 7 illustrates one example of an energy transfer element
208. In this example the energy transfer element 208 is a
"basket-type" configuration that requires actuation for expansion
of the basket in diameter. Such a feature is useful when the device
is operated intralumenally or in anatomy such as the lungs due to
the varying size of the bronchial passageways that may require
treatment. As illustrated, the basket contains a number of arms 220
which carry electrodes (not shown). In this variation the arms 220
are attached to the elongated shaft 204 at a proximal end while the
distal end of the arms 220 are affixed to a distal tip 222. To
actuate the basket 208 a wire or tether 224 is affixed to the
distal tip 222 to enable compression of the arms 220 between the
distal tip 222 and elongate sheath 204.
[0125] FIG. 7 also illustrates the device 100 as being advanced
through a working channel 232 of a bronchoscope 318. While a
bronchoscope 318 may assist in the procedure, the device 100 may be
used through direct insertion or other insertion means as well.
[0126] As noted above, some variations of the devices described
herein have sufficient lengths to reach remote parts of the body
(e.g., bronchial passageways around 3 mm in diameter). FIG. 8
illustrates a configuration that reduces the force required to
actuate the device's basket or other energy transfer element.
[0127] FIG. 8 illustrates a cross section taken from the sheath 202
and elongate shaft 204. As shown, the sheath 202 includes an outer
layer 226 and an inner lubricious layer 228. The outer layer 226
may be any commonly known polymer such as Nylon, PTFE, etc. The
lubricious layers 228 discussed herein may comprise a lubricious
polymer (for example, HDPE, hydrogel, polytetrafluoroethylene).
Typically, lubricious layer 228 will be selected for optimal
pairing with the shaft 204. One means to select a pairing of
polymers is to maximize the difference in Gibbs surface energy
between the two contact layers. Such polymers may also be chosen to
give the lubricious layer 228 a different modulus of elasticity
than the outer layer 226. For example, the modulus of the
lubricious layer 228 may be higher or lower than that of the outer
layer 226.
[0128] Alternatively, or in combination, the lubricious layers may
comprise a fluid or liquid (e.g., silicone, petroleum based oils,
food based oils, saline, etc.) that is either coated or sprayed on
the interface of the shaft 204 and sheath 202. The coating may be
applied at the time of manufacture or at time of use. Moreover, the
lubricious layers 228 may even include polymers that are treated
such that the surface properties of the polymer changes while the
bulk properties of the polymer are unaffected (e.g., via a process
of plasma surface modification on polymer, fluoropolymer, and other
materials). Another feature of the treatment is to treat the
surfaces of the devices with substances that provide
antibacterial/antimicrobial properties.
[0129] In one variation of the invention, the shaft 204 and/or
sheath 202 will be selected from a material to provide sufficient
column strength to advance the expandable energy transfer element
within the anatomy. Furthermore, the materials and or design of the
shaft/sheath will permit a flexibility that allows the energy
transfer element to essentially self-align or self-center when
expanded to contact the surface of the body passageway. For
example, when advanced through tortuous anatomy, the flexibility of
this variation should be sufficient that when the energy transfer
element expands, the shaft and/or sheath deforms to permit
self-centering of the energy transfer element. It is noted that the
other material selection and/or designs described herein shall aid
in providing this feature of the invention.
[0130] FIG. 8 also depicts a variation of a shaft 204 for use in
the present device. In this variation the shaft 204 includes a
corrugated surface 230. It is envisioned that the corrugated
surface 230 may include ribbed, textured, scalloped, striated,
undercut, polygonal, or any similar geometry resulting in a reduced
area of surface contact with any adjoining surface(s). The
corrugated surface 230 may extend over a portion or the entire
length of the shaft 204. In addition, the shape of the corrugations
may change at varying points along the shaft 204.
[0131] The shaft 204 may also include one or more lumens 232, 234.
Typically, one lumen will suffice to provide power to the energy
transfer elements (as discussed below). However, in the variation
shown, the shaft may also benefit from additional lumens (such as
lumens 234) to support additional features of the device (e.g.,
temperature sensing elements, other sensor elements such as
pressure or fluid sensors, utilizing different lumens for different
sensor leads, and fluid delivery or suctioning, etc.). In addition
the lumens may be used to deliver fluids or suction fluid to assist
in managing the moisture within the passageway. Such management may
optimize the electrical coupling of the electrode to the tissue
(by, for example, altering impedance). Since the device is suited
for use in tortuous anatomy, a variation of the shaft 204 may have
lumens 234 that are symmetrically formed about an axis of the
shaft. As shown, the additional lumens 234 are symmetric about the
shaft 204. This construction provides the shaft 204 with a cross
sectional symmetry that aid in preventing the shaft 204 from being
predisposed to flex or bend in any one particular direction.
[0132] The invention herein is described by examples and a desired
way of practicing the invention is described. However, the
invention as claimed herein is not limited to that specific
description in any manner. Equivalence to the description as
hereinafter claimed is considered to be within the scope of
protection of this patent.
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