Patent Publication Number: US-2023136081-A1

Title: High resistance implanted bronchial isolation devices and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/941,442 (Attorney Docket No. 20920-776.501), filed Jul. 28, 2020, which is a continuation-in-part of U.S. patent application Ser. No. 15/714,868 (Attorney Docket No. 20920-776.201), filed Sep. 25, 2017, now U.S. Pat. No. 10,758,333, which claims the benefit of U.S. Provisional No. 62/404,688 (Attorney Docket No. 20920-776.101), filed Oct. 5, 2016, the full disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This disclosure relates generally to methods and devices for use in performing pulmonary procedures and, more particularly, to procedures for treating lung diseases. 
     BACKGROUND OF THE INVENTION 
     Pulmonary diseases, such as chronic obstructive pulmonary disease, (COPD), reduce the ability of one or both lungs to fully expel air during the exhalation phase of the breathing cycle. Such diseases are accompanied by chronic or recurrent obstruction to air flow within the lung. Because of the increase in environmental pollutants, cigarette smoking, and other noxious exposures, the incidence of COPD has increased dramatically in the last few decades and now ranks as a major cause of activity-restricting or bed-confining disability in the United States. COPD can include such disorders as chronic bronchitis, bronchiectasis, asthma, and emphysema. 
     It is known that emphysema and other pulmonary diseases reduce the ability of one or both lungs to fully expel air during the exhalation phase of the breathing cycle. One of the effects of such diseases is that the diseased lung tissue is less elastic than healthy lung tissue, which is one factor that prevents full exhalation of air. During breathing, the diseased portion of the lung does not fully recoil due to the diseased (e.g., emphysematic) lung tissue being less elastic than healthy tissue. 
     Consequently, the diseased lung tissue exerts a relatively low driving force, which results in the diseased lung expelling less air volume than a healthy lung. The reduced air volume exerts less force on the airway, which allows the airway to close before all air has been expelled, another factor that prevents full exhalation. 
     The problem is further compounded by the diseased, less elastic tissue that surrounds the very narrow airways that lead to the alveoli, which are the air sacs where oxygen-carbon dioxide exchange occurs. The diseased tissue has less tone than healthy tissue and is typically unable to maintain the narrow airways open until the end of the exhalation cycle. This traps air in the lungs and exacerbates the already-inefficient breathing cycle. The trapped air causes the tissue to become hyper-expanded and no longer able to effect efficient oxygen-carbon dioxide exchange. 
     In addition, hyper-expanded, diseased lung tissue occupies more of the pleural space than healthy lung tissue. In most cases, a portion of the lung is diseased while the remaining part is relatively healthy and, therefore, still able to efficiently carry out oxygen exchange. By taking up more of the pleural space, the hyper-expanded lung tissue reduces the amount of space available to accommodate the healthy, functioning lung tissue. As a result, the hyper-expanded lung tissue causes inefficient breathing due to its own reduced functionality and because it adversely affects the functionality of adjacent healthy tissue. 
     Some recent treatments include the use of devices that isolate a diseased region of the lung in order to reduce the volume of the diseased region, such as by collapsing the diseased lung region. According to such treatments, one or more flow control devices are implanted in airways feeding a diseased region of the lung to regulate fluid flow to the diseased lung region in order to fluidly isolate the region of the lung. These implanted flow control devices can be, for example, one-way valves that allow flow in the exhalation direction only, occluders or plugs that prevent flow in either direction, or two-way valves that control flow in both directions. However, such devices are still in the development stages. 
     Thus, there is much need for improvement in the design and functionality of such flow control devices. 
     SUMMARY OF THE INVENTION 
     Disclosed are methods and devices for regulating fluid flow to and from a region of a patient&#39;s lung, such as to achieve a desired fluid flow dynamic to a lung region during respiration and/or to induce collapse in one or more lung regions. In one aspect, a flow control device suitable for implanting in a bronchial passageway is described. The flow control device comprises a valve element comprising a first lip and a second lip, wherein the first and second lips are configured to transition the valve element between a closed configuration that blocks air flow in the inspiratory direction and an open configuration that permits air flow in an expiratory direction. The first and second lips are configured to be in the closed configuration when exposed to no air flow, air flow in the inspiratory direction, and air flow in the expiratory direction at normal breathing pressures. The first and second lips may be additionally configured to be in the open configuration when exposed to air flow in the expiratory direction in the range of 12-24 inches H 2 O. The first and second lips may be configured to be in the open configuration when exposed to air flow in the expiratory direction in the range of 121-160 inches H 2 O. 
     In an embodiment, the first and second lips are configured to be parallel with respect to one another in the closed configuration. The valve element may further comprise two opposed inclined flaps leading to the first and second lips, wherein the two inclined flaps are oriented at an angle with respect to one another. The angle may be in the range of 70 to 110 degrees. The first and second lips may be configured to be parallel with a longitudinal axis of the valve while in the closed configuration. The two inclined flaps may be oriented at an angle relative to a longitudinal axis of the valve while in the closed configuration. In an embodiment, the flow control device may further comprise a frame configured to retain the flow control device within the bronchial passageway and a seal coupled to the frame. In an embodiment, the length of the parallel and contacted parallel lips extending longitudinally beyond the two inclined flaps is at least 30% as long as a length of the inclined flaps. The seal may be configured to seal against internal walls of the bronchial passageway. 
     In one aspect, the flow control device comprises a valve comprising coaptation regions comprising two opposed inclined flaps and two parallel lips connected to the inclined flaps, wherein the coaptation regions are configured to transition the valve element between a closed configuration that blocks air flow in the inspiratory direction and an open configuration that permits air flow in an expiratory direction. The coaptation regions are configured to be in the closed configuration when exposed to no air flow, air flow in the inspiratory direction, and air flow in the expiratory direction at normal breathing pressures, and wherein the coaptation regions are configured to be in the open configuration when exposed to air flow in the expiratory direction at coughing pressures. 
     This and other aspects of the present disclosure are described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Present embodiments have other advantages and features which will be more readily apparent from the following detailed description and the appended claims, when taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    shows an anterior view of a pair of human lungs and a bronchial tree with a flow control device implanted in a bronchial passageway to bronchially isolate a region of the lung. 
         FIG.  2    illustrates an anterior view of a pair of human lungs and a bronchial tree 
         FIG.  3 A  illustrates a lateral view of the right lung. 
         FIG.  3 B  illustrates a lateral view of the left lung. 
         FIG.  4    illustrates an anterior view of the trachea and a portion of the bronchial tree. 
         FIG.  5 A  shows a perspective view of an exemplary flow control device that can be implanted in a body passageway. 
         FIG.  5 B  shows a perspective, cross-sectional view of the flow control device of  FIG.  5 A . 
         FIG.  6 A  shows a side view of the flow control device of  FIG.  5 A . 
         FIG.  6 B  shows a cross-sectional, side view of the flow control device of  FIG.  5 A . 
         FIG.  7    shows another embodiment of a flow control device. 
         FIG.  8 A  shows a side, cross-sectional view of a duckbill valve in a closed state. 
         FIG.  8 B  shows a side, cross-sectional view of a duckbill valve in an open state. 
         FIG.  9    shows a side, cross-sectional view of a duckbill valve with a cracking pressure above normal breathing pressures. 
         FIGS.  10 A- 10 E  show an exemplary duckbill valve with a cracking pressure above normal breathing pressures. 
         FIGS.  11 A- 11 E  show an alternative duckbill valve with a cracking pressure above normal breathing pressures. 
         FIGS.  12 A- 12 E  show an embodiment of a duckbill valve with a cracking pressure above normal breathing pressures. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope. 
     Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of “a”, “an”, and “the” include plural references. The meaning of “in” includes “in” and “on.” Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as advantageous over other implementations. 
     Disclosed are methods and devices for regulating fluid flow to and from a region of a patient&#39;s lung, such as to achieve a desired fluid flow dynamic to a lung region during respiration and/or to induce collapse in one or more lung regions. Pursuant to an exemplary procedure, an identified region of the lung (referred to herein as the “targeted lung region”) is targeted for treatment. The targeted lung region is then bronchially isolated to regulate airflow into and/or out of the targeted lung region through one or more bronchial passageways that feed air to the targeted lung region. 
     As shown in  FIG.  1   , the bronchial isolation of the targeted lung region is accomplished by implanting a flow control device  110  (sometimes referred to as a bronchial isolation device) into a bronchial passageway  115  that feeds air to a targeted lung region  120 . The flow control device  110  regulates fluid flow through the bronchial passageway  115  in which the flow control device  110  is implanted. The flow control device  110  can regulate airflow through the bronchial passageway  115  using a valve that permits fluid flow in a first direction (e.g., the exhalation direction) while limiting or preventing fluid flow in a second direction (e.g., the inhalation direction). 
     The valve includes coaptation regions that are moveable toward and away from one another so as to define an opening through which fluid can flow. When exposed to fluid flow with sufficient pressure in the first direction (e.g., the exhalation direction), the coaptation regions are urged away from one another permit fluid flow through the valve. When exposed to fluid flow in the second direction (e.g., the inhalation direction), the coaptation regions are urged toward one another to decrease the size of and/or completely close the opening to decrease and/or completely prevent fluid flow through the valve. Flow through the valve is completely prevented when the coaptation regions are completely shut such that there is no opening for fluid to flow through the valve. 
     As described in detail below, the flow control device  110  can include a valve that is closed in a default state such that there is no gap or opening between the coaptation regions of the valve. The coaptation regions separate from one another to form an opening for fluid flow in the first direction when the valve cracking pressure is exceeded. For such a valve, there is a tendency for the coaptation regions, such as the valve lips, to stick together so as to resist opening and thereby increase the valve cracking pressure. The sticking force between the coaptation regions can be stronger when the valve is implanted in a lung, as mucous can coat the valve lips and form surface tension that must be overcome to separate the lips and open the valve. 
     Throughout this disclosure, reference is made to the term “lung region”. As used herein, the term “lung region” refers to a defined division or portion of a lung. For purposes of example, lung regions are described herein with reference to human lungs, wherein some exemplary lung regions include lung lobes and lung segments. Thus, the term “lung region” as used herein can refer, for example, to a lung lobe or a lung segment. Such nomenclature conform to nomenclature for portions of the lungs that are known to those skilled in the art. However, it should be appreciated that the term “lung region” does not necessarily refer to a lung lobe or a lung segment, but can refer to some other defined division or portion of a human or nonhuman lung. 
       FIG.  2    shows an anterior view of a pair of human lungs  210 ,  215  and a bronchial tree  220  that provides a fluid pathway into and out of the lungs  210 ,  215  from a trachea  225 , as will be known to those skilled in the art. As used herein, the term “fluid” can refer to a gas, a liquid, or a combination of gas(es) and liquid(s). For clarity of illustration,  FIG.  2    shows only a portion of the bronchial tree  220 , which is described in more detail below with reference to  FIG.  5   . 
     Throughout this description, certain terms are used that refer to relative directions or locations along a path defined from an entryway into the patient&#39;s body (e.g., the mouth or nose) to the patient&#39;s lungs. The path of airflow into the lungs generally begins at the patient&#39;s mouth or nose, travels through the trachea into one or more bronchial passageways, and terminates at some point in the patient&#39;s lungs. For example,  FIG.  2    shows a path  202  that travels through the trachea  225  and through a bronchial passageway into a location in the right lung  210 . The term “proximal direction” refers to the direction along such a path  202  that points toward the patient&#39;s mouth or nose and away from the patient&#39;s lungs. In other words, the proximal direction is generally the same as the expiration direction when the patient breathes. The arrow  204  in  FIG.  2    points in the proximal or expiratory direction. The term “distal direction” refers to the direction along such a path  202  that points toward the patient&#39;s lung and away from the mouth or nose. The distal direction is generally the same as the inhalation or inspiratory direction when the patient breathes. The arrow  206  in  FIG.  2    points in the distal or inhalation direction. 
     The lungs include a right lung  210  and a left lung  215 . The right lung  210  includes lung regions comprised of three lobes, including a right upper lobe  230 , a right middle lobe  235 , and a right lower lobe  240 . The lobes  230 ,  235 ,  240  are separated by two interlobar fissures, including a right oblique fissure  226  and a right transverse fissure  228 . The right oblique fissure  226  separates the right lower lobe  240  from the right upper lobe  230  and from the right middle lobe  235 . The right transverse fissure  228  separates the right upper lobe  230  from the right middle lobe  235 . 
     As shown in  FIG.  2   , the left lung  215  includes lung regions comprised of two lobes, including the left upper lobe  250  and the left lower lobe  255 . An interlobar fissure comprised of a left oblique fissure  245  of the left lung  215  separates the left upper lobe  250  from the left lower lobe  255 . The lobes  230 ,  235 ,  240 ,  250 ,  255  are directly supplied air via respective lobar bronchi, as described in detail below. 
       FIG.  3 A  is a lateral view of the right lung  210 . The right lung  210  is subdivided into lung regions comprised of a plurality of bronchopulmonary segments. Each bronchopulmonary segment is directly supplied air by a corresponding segmental tertiary bronchus, as described below. The bronchopulmonary segments of the right lung  210  include a right apical segment  310 , a right posterior segment  320 , and a right anterior segment  330 , all of which are disposed in the right upper lobe  230 . The right lung bronchopulmonary segments further include a right lateral segment  340  and a right medial segment  350 , which are disposed in the right middle lobe  235 . The right lower lobe  240  includes bronchopulmonary segments comprised of a right superior segment  360 , a right medial basal segment (which cannot be seen from the lateral view and is not shown in  FIG.  3 A ), a right anterior basal segment  380 , a right lateral basal segment  390 , and a right posterior basal segment  395 . 
       FIG.  3 B  shows a lateral view of the left lung  215 , which is subdivided into lung regions comprised of a plurality of bronchopulmonary segments. The bronchopulmonary segments include a left apical segment  410 , a left posterior segment  420 , a left anterior segment  430 , a left superior segment  440 , and a left inferior segment  450 , which are disposed in the left lung upper lobe  250 . The lower  15  lobe  225  of the left lung  215  includes bronchopulmonary segments comprised of a left superior segment  460 , a left medial basal segment (which cannot be seen from the lateral view and is not shown in  FIG.  3 B ), a left anterior basal segment  480 , a left lateral basal segment  490 , and a left posterior basal segment  495 . 
       FIG.  4    shows an anterior view of the trachea  225  and a portion of the bronchial tree  220 , which includes a network of bronchial passageways, as described below. In the context of describing the lung, the terms “pathway” and “lumen” are used interchangeably herein. The trachea  225  divides at a lower end into two bronchial passageways comprised of primary bronchi, including a right primary bronchus  510  that provides direct air flow to the right lung  210 , and a left primary bronchus  515  that provides direct air flow to the left lung  215 . Each primary bronchus  510 ,  515  divides into a next generation of bronchial passageways comprised of a plurality of lobar bronchi. The right primary bronchus  510  divides into a right upper lobar bronchus  517 , a right middle lobar bronchus  520 , and a right lower lobar bronchus  522 . The left primary bronchus  515  divides into a left upper lobar bronchus  525  and a left lower lobar bronchus  530 . Each lobar bronchus,  517 ,  520 ,  522 ,  525 ,  530  directly feeds fluid to a respective lung lobe, as indicated by the respective names of the lobar bronchi. The lobar bronchi each divide into yet another generation of bronchial passageways comprised of segmental bronchi, which provide air flow to the bronchopulmonary segments discussed above. 
     As is known to those skilled in the art, a bronchial passageway defines an internal lumen through which fluid can flow to and from a lung or lung region. The diameter of the internal lumen for a specific bronchial passageway can vary based on the bronchial passageway&#39;s location in the bronchial tree (such as whether the bronchial passageway is a lobar bronchus or a segmental bronchus) and can also vary from patient to patient. However, the internal diameter of a bronchial passageway is generally in the range of 3 millimeters (mm) to 10 mm, although the internal diameter of a bronchial passageway can be outside of this range. For example, a bronchial passageway can have an internal diameter of well below 1 mm at locations deep within the lung. 
     Flow Control Device. Some of the breathing patterns that are characteristic of patients with severe emphysema are that the patients are able to inhale very easily and yet exhale with great difficulty. The destruction of lung parenchyma in the diseased regions of the lung leads to a loss of elastic recoil for the diseased lung region. The resulting imbalance in elastic recoil between diseased and healthier lung regions results in the diseased lung regions filling with air easily and first during inspiration. However, the diseased regions empty last and with great difficulty during expiration, as there is little or no elastic recoil remaining in the diseased lung regions to assist in the expelling of air. Adding to this difficulty, the distal airways in the diseased lung regions collapse during exhalation due to the loss of tethering forces that hold the airways open during exhalation in normal lung regions. As pleural pressure increases at the beginning of expiration, these distal airways partially or fully collapse, thus decreasing the exhalation flow, and increasing the work and time required for the patient to fully exhale. 
     To help ease the symptoms of emphysema and to improve breathing mechanics, implantation of one-way flow control devices or valve bronchial isolation devices has been employed, as described in several prior U.S. patent applications, including “Methods and Devices for use in Performing Pulmonary Procedures”, Ser. No. 09/797,910, filed Mar. 2, 2001, “Bronchial Flow Control Devices and Methods of Use”, Ser. No. 10/270,792, filed Oct. 10, 2002, and “Implanted Bronchial Isolation Devices And Methods”, Ser. No. 12/885,199, filed Sep. 17, 2010 which are incorporated herein by reference. 
       FIGS.  5 A- 6 B  show an exemplary embodiment of a flow control device  110  that generally includes a valve, a frame or anchor, and a seal member for sealing against a wall of a bronchial passageway. It should be appreciated that the flow control device  110  shown in  FIGS.  5 A- 6 B  is exemplary and that the frame, seal member, and valve can vary in structure. The flow control device  110  has a general outer shape and contour that permits the flow control device  110  to fit entirely or at least partially within a body passageway, such as within a bronchial passageway. 
     The valve is configured to regulate fluid flow through a bronchial passageway in which the device  110  is implanted. The valve opens and vents fluid (such as gas or liquid, including mucous) when the pressure across the valve due to flow in a first direction, such as the exhalation direction, exceeds the rated cracking pressure of the valve. Thus, the valve opens in response to fluid flow in the first direction. The valve moves towards a closed configuration in response to fluid flow in a second, opposite direction such as the inhalation direction. 
     With reference to  FIGS.  5 A- 6 B , the flow control device  110  extends generally along a central axis  605  (shown in  FIGS.  5 B and  6 B ). The flow control device  110  includes a main body that defines an interior lumen  610  through which fluid can flow along a flow path. The dimensions of the flow control device  110  can vary based upon the bronchial passageway in which the flow control device  110  is configured to be implanted. The valve does not have to be precisely sized for the bronchial passageway it is to be placed within. Generally, the diameter D (shown in  FIG.  6 A ) of the flow control device  110  in the uncompressed state is larger than the inner diameter of the bronchial passageway in which the flow control device  110  will be placed. This will permit the flow control device  110  to be compressed prior to insertion in the bronchial passageway and then expand upon insertion in the bronchial passageway, which will provide for a secure fit between the flow control device  110  and the bronchial passageway. 
     The flow of fluid through the interior lumen  610  is controlled by a valve  612  that is disposed at a location along the interior lumen such that fluid must flow through the valve  612  in order to flow through the interior lumen  610 . It should be appreciated that the valve  612  could be positioned at various locations along the interior lumen  610 . The valve  612  can be made of a biocompatible material, such as a biocompatible polymer, such as silicone. As discussed in more detail below, the configuration of the valve  612  can vary based on a variety of factors, such as the desired cracking pressure of the valve  612 . 
     The valve  612  can be configured to permit fluid to flow in only one-direction through the interior lumen  610 , to permit regulated flow in two-directions through the interior lumen  610 , or to prevent fluid flow in either direction. 
     With reference still to  FIGS.  5 A- 6 B , the flow control device  110  includes a seal member  615  that provides a seal with the internal walls of a body passageway when the flow control device is implanted into the body passageway. The seal member  615  is manufactured of a deformable material, such as silicone or a deformable elastomer. The flow control device  110  also includes an anchor member or frame  625  that functions to anchor the flow control device  110  within a body passageway. 
     As shown in  FIGS.  5 A- 6 B , the seal member  615  can includes a series of radially-extending, circular flanges  620  that surround the outer circumference of the flow control device  110 . The configuration of the flanges can vary. For example, as shown in  FIG.  6 B , the radial length of each flange  620  can vary. It should be appreciated that the radial length could be equal for all of the flanges  620  or that the radial length of each flange could vary in some other manner. In addition, the flanges  620  can be oriented at a variety of angles relative to the longitudinal axis  605  of the flow control device. 
     As mentioned, the anchor member  625  functions to anchor the flow control device  110  in place when the flow control device is implanted within a body passageway, such as within a bronchial passageway. The anchor member  625  has a structure that can contract and expand in size (in a radial direction and/or in a longitudinal direction) so that the anchor member can expand to grip the interior walls of a body passageway in which the flow control device is positioned. In one embodiment, as shown in  FIGS.  5 A- 6 B , the anchor member  625  comprises an annular frame that surrounds the flow control device  110 . 
     The frame  625  can be formed from a super-elastic material, such as Nickel Titanium (also known as Nitinol), such as by cutting the frame out of a tube of Nitinol or by forming the frame out of Nitinol wire. The super-elastic properties of Nitinol can result in the frame exerting a radial force against the interior walls of a bronchial passageway sufficient to anchor the flow control device  110  in place. 
     It should be appreciated that the configurations, including the sizes and shapes, of the frame  625  and the seal member  615  can vary from those shown in the figures. The seal  615  and/or the frame  625  can contract or expand in size, particularly in a radial direction. The default state is an expanded size, such that the flow control device  110  will have a maximum diameter (which is defined by either the seal  615  or the frame  625 ) when the flow control device  110  is in the default state. The flow control device  110  can be radially contracted in size during insertion into a bronchial passageway, so that once the flow control device  110  is inserted into the passageway, it expands within the passageway. 
     At least a portion of the valve  612  is optionally surrounded by a rigid or semirigid valve protector member  637  (shown in  FIGS.  5 B and  6 B ), which is a tubular member or annular wall that is contained inside the seal member  615 . In another embodiment, the valve protector can comprise a coil of wire or a ring of wire that provides some level of structural support to the flow control device. The valve protector  637  can be concentrically located within the seal member  615 . Alternately, the valve  612  can be completely molded within the seal member  615  such that the material of the seal member  615  completely surrounds the valve protector. The valve protector has sufficient rigidity to maintain the shape of the valve member against compression. 
     In one embodiment, the valve protector member  637  has two or more windows  639  comprising holes that extend through the valve protector member, as shown in  FIG.  6 B . The windows  639  can provide a location where a removal device, such as graspers or forceps, can be inserted in order to facilitate removal of the flow control device  110  from a bronchial passageway. 
     As mentioned, the structural configuration of the flow control device can vary. For example,  FIG.  7    shows a perspective view of another embodiment of a flow control device  110  that includes a frame  625 , a valve  612  mounted in the frame  625 , and a membrane  627 . The frame  625  and the membrane  627  can collectively or individually seal with an internal wall of a bronchial passageway. 
     The device  110  in  FIG.  7    includes an elastically expandable frame  625  that is covered with an elastomeric membrane  627 . In one embodiment, the device has an expanded frame laser-cut from nitinol tubing that has been expanded and heat treated to set it in the shape shown. The frame  625  is dipped in a silicone dispersion so that all outer surfaces are covered in a thin silicone membrane. 
     When the device is compressed into a delivery catheter, it may be delivered through the trachea, using any of a number of well-known delivery methods, to the target bronchial lumen, and released from the catheter. Once released, the device expands and grips the walls of the bronchial lumen, and due to the silicone membrane, blocks fluid (gas and liquid) flow through the lumen in both the inhalation and exhalation directions. The frame  625  can have points or prongs on the distal end to prevent migration of the device in the distal or inhalation direction. 
     Of course, the frame may be made of other materials and take other shapes, may be deformable or heat expandable rather than spring resilient, and the membrane may be formed from other materials (such as urethane) and may be manufactured using methods other than dipping. This particular device is compact enough to fit into a delivery catheter that can fit through the working channel of a bronchoscope that has an internal diameter of 2.2 mm, however it may be delivered using other methods. 
     As discussed above, exemplary implantable one-way valve flow control devices are shown in  FIG.  5 A- 7   . A valve of a flow control device includes regions (referred to herein as coaptation regions) that contact one another to block flow through the valve, and separate from one another to allow flow through the valve. The coaptation regions can contact one another along their entire length or area such that there is no gap between therebetween and the valve is completely closed. 
     The valve coaptation regions may be in full contact with one another in a default state, such as when there is no pressure differential across the valve. That is, the coaptation regions are in contact with one another such that there is no opening for fluid to flow through. As mentioned, the default state is the state of the valve when exposed to no fluid flow and, therefore, no pressure differential across the valve. When a valve is “closed” the valve coaptation regions contact one another so as to block flow through the valve when there is no pressure differential across the valve. 
     The valve member  612  can be any type of fluid valve, and preferably is a valve that enables the cracking pressures described herein. The valve member  612  can have a smaller diameter than the frame  625  so that compression or deformation of the frame  625  in both a radial and axial direction will have little or no impact on the structure of the valve member  612 . In the embodiment shown in  FIGS.  5 - 7   , the valve member  612  comprises a duckbill valve that includes two flaps  631  (shown in  FIGS.  5 B and  6 B ) that are oriented at an angle with respect to one another and that can open and close with respect to one another so as to form an opening at a lip  801  ( FIG.  6 B ) where the flaps  631  touch one another. The duckbill valve allows fluid flow in a first direction and prevents fluid flow in a second direction that is opposed to the first direction. For example,  FIG.  8 A  shows a schematic side-view of a duckbill valve in a closed state, wherein the flaps  631  touch one another at the lip  801 . In the closed state, the duckbill valve prevents fluid flow in a first direction, which is represented by the arrow A in  FIG.  8 A . However, when exposed to fluid flow with sufficient pressure in a second direction (represented by arrow B in  FIG.  8 B ) that is opposed to the first direction, the flaps  631  separate from one another to form an opening between the flaps  631  that permits flow in the second direction, as shown in  FIG.  8 B . 
     The cracking pressure is defined as the minimum fluid pressure necessary to open the one-way valve member in a certain direction, such as in the distal-to-proximal direction. Given that the valve member of the flow control device  110  will be implanted in a bronchial lumen of the human lung, the flow control device  110  will likely be coated with mucus and fluid at all times. For this reason, the cracking pressure of the valve is desirably tested in a wet condition that simulates the conditions of a bronchial lumen. A representative way of testing the valve member is to use a small amount of a water based lubricant to coat the valve mouth. The testing procedure for a duckbill valve is as follows: 1. Manually open the mouth of the valve member, such as by pinching the sides of the valve together, and place a drop of a dilute water based lubricant between the lips of the valve. 2. Wipe excess lubricant off of the valve, and force 1 cubic centimeter of air through the valve in the forward direction to push out any excess lubricant from the inside of the valve. 3. Connect the distal side of the valve to an air pressure source, and slowly raise the pressure. The pressure is increased from a starting pressure of 0 inches H 2 O up to a maximum of 10 inches H 2 O over a period of time (such as 3 seconds), and the peak pressure is recorded. This peak pressure represents the cracking pressure of the valve. 
     The cracking pressure of the valve member can vary based on various physiological conditions. For example, the cracking pressure could be set relative to a coughing pressure, a forced expiration pressure, or a normal respiration pressure. For example, the cracking pressure could be set so that it is higher than normal respiration pressure and lower than a coughing pressure (approximately 25 inches H 2 O). In this regard, the normal or coughing respiration pressure can be determined based on a particular patient, or it could be determined based on average normal or coughing respiration pressures. In one embodiment, the cracking pressure of the valve member is in the range of approximately 5-25 inches H 2 O. In another embodiment, the cracking pressure of the valve is in the range of approximately 7-9 inches H 2 O. In yet another embodiment, the cracking pressure of the valve is in the range of approximately 11-24 inches H 2 O. The cracking pressure of the valve may be set also be set above 25 inches H 2 O. In an embodiment, the cracking pressure of the valve is in the range of approximately 26-120 inches H 2 O. The cracking pressure of the valve may also be set above 120 inches H 2 O. In an embodiment the cracking pressure of the valve is in the range of approximately 121-160 inches H 2 O. The cracking pressure of the valve may also be set above 160 inches H 2 O. 
     It may be desirable to have a valve with a cracking pressure above normal breathing pressures in order to reduce the risk of the targeted lung region collapsing too quickly. Thus, the cracking pressure may be set such that the valve will not open with an exhale but will open with a cough or forced exhalation. Such a valve will act like a plug during normal breathing but will allow mucus to pass during a cough or forced exhalation. 
     An example of a valve with a cracking pressure above normal breathing pressures is shown in  FIG.  9   . The valve  912  comprises a duckbill valve that includes two opposed, inclined walls or flaps  931  that are oriented at an angle  913  with respect to one another and lips  910  configured to be parallel with respect to one another in the closed configuration. The flaps  931  can open and close with respect to one another so as to form an opening between the lips  910 . The relative positions of the lips  910  determines the size of the opening in the valve  912 . When the lips  910  are in full contact with one another, there is no opening between the coaptation regions. In an embodiment, the inclined walls or flaps  931  are oriented at an angle relative to the longitudinal axis  905  of the valve while in the closed configuration. The lips may be configured to be parallel with the longitudinal axis  905  of the valve while in the closed configuration. 
     Various characteristics of the valve  912  may be varied to increase (or decrease) the cracking pressure of the valve  912 . For example, the smaller the duckbill valve, the higher the cracking pressure that is generally required to open the valve. In addition, increasing the thickness  932  of a wall of the valve  912  will increase the cracking pressure. A longer parallel lip length  911  will also increase the cracking pressure of the valve  912 . Increasing the angle  913  between the inclined walls or flaps  931  will increase the cracking pressure of the valve  912 . In an embodiment, the angle  913  between the inclined walls or flaps  931  is in the range of approximately 70 to 110 degrees. The cracking pressure is also increased by orienting the valve  912  more orthogonal to the direction of flow. In an embodiment the valve  912  is oriented at an angle with respect to the direction of air flow through the bronchial passageway. Additionally, the cracking pressure may be increased by narrowing the opening slit cut between the parallel lips  910 . 
       FIGS.  10 A- 12 E  show various embodiments of valves with cracking pressures above normal breathing. The valves  1012 ,  1112 ,  1212  comprise inclined walls or flaps  1031 ,  1131 ,  1231  that are oriented at an angle with respect to one another and lips  1010 ,  1110 ,  1210  configured to be parallel with respect to one another in the closed configuration. The flaps  1031 ,  1131 ,  1231  can open and close with respect to one another so as to form an opening between the lips  1010 ,  1110 ,  1210 . The relative positions of the lips  1010 ,  1110 ,  1210  determines the size of the opening in the valve  1012 ,  1112 ,  1212 . When the lips  1010 ,  1110 ,  1210  are in full contact with one another, there is no opening between the coaptation regions. In some embodiments a length of parallel and contacted lips  1010 ,  1110 ,  1210  extending longitudinally beyond the inclined flaps  1031 ,  1131 ,  1231  is at least 30% as long as a length of the inclined flaps  1031 ,  1131 ,  1231 . In other embodiments a length of parallel and contacted lips  1010 ,  1110 ,  1210  extending longitudinally beyond the inclined flaps  1031 ,  1131 ,  1231  is at least 40% or 50% as long as a length of the inclined flaps  1031 ,  1131 ,  1231 . 
     While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.