Patent Publication Number: US-2007123922-A1

Title: Devices and methods for maintaining collateral channels in tissue

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation of U.S. patent application Ser. No. 09/947,144 filed on Sep. 4, 2001 which is a non-provisional of U.S. Provisional Patent Application Ser. No. 60/269,130, filed on Feb. 14, 2001, both of which are incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION  
      The invention is directed to devices and methods of placing such devices to altering gaseous flow within a lung to improve the expiration cycle of an individual, particularly individuals having Chronic Obstructive Pulmonary Disease (COPD). More particularly, methods and devices are disclosed to produce and to maintain collateral openings or channels through the airway wall so that oxygen depleted/carbon dioxide rich air is able to pass directly out of the lung tissue to facilitate both the exchange of oxygen ultimately into the blood and/or to decompress hyper-inflated lungs. The invention is also directed to medical kits disclosed which produce and maintain collateral openings through airway walls.  
     BACKGROUND OF THE INVENTION  
      The term “Chronic Obstructive Pulmonary Disease” (COPD) is generally used to describe the disorders of emphysema and chronic bronchitis. Previously, COPD was also known as Chronic Obstructive Lung Disease (COLD), Chronic Airflow Obstruction (CAO), or Chronic Airflow Limitation (CAL). Some also consider certain types of asthma to fall under the definition of COPD. Emphysema is characterized by an enlargement of air spaces inside the lung. Hence, emphysema is an anatomic definition and it can only be presumed in a living patient. Chronic bronchitis is characterized by excessive mucus production in the bronchial tree. Chronic bronchitis is a clinical definition and denotes those individuals who meet criteria defining the disease. It is not uncommon for an individual to suffer from both disorders.  
      In 1995, the American Lung Association (ALA) estimated that between 15-16 million Americans suffered from COPD. The ALA estimated that COPD was the fourth-ranking cause of death in the U.S. The ALA estimates that the rates of emphysema is 7.6 per thousand population, and the rate for chronic bronchitis is 55.7 per thousand population.  
      Those inflicted with COPD face disabilities due to the limited pulmonary functions. Usually, individuals afflicted by COPD also face loss in muscle strength and an inability to perform common daily activities. Often, those patients desiring treatment for COPD seek a physician at a point where the disease is advanced. Since the damage to the lungs is irreversible, there is little hope of recovery. Most times, the physician cannot reverse the effects of the disease but can only offer treatment and advice to halt the progression of the disease.  
      To understand the detrimental effects of COPD, the workings of the lungs requires a cursory discussion. The primary function of the lungs is to permit the exchange of two gasses by removing carbon dioxide from venous blood and replacing it with oxygen. Thus, to facilitate this exchange, the lungs provide a blood gas interface. The oxygen and carbon dioxide move between the gas (air) and blood by diffusion. This diffusion is possible since the blood is delivered to one side of the blood-gas interface via small blood vessels (capillaries). The capillaries are wrapped around numerous air sacs called alveoli which function as the blood-gas interface. A typical human lung contains about 300 million alveoli.  
      The air is brought to the other side of this blood-gas interface by a natural respiratory airway, hereafter referred to as a natural airway or airway, consisting of branching tubes which become narrower, shorter, and more numerous as they penetrate deeper into the lung. Specifically, the airway begins with the trachea which branches into the left and right bronchi which divide into lobar, then segmental bronchi. Ultimately, the branching continues down to the terminal bronchioles which lead to the alveoli. Plates of cartilage may be found as part of the walls throughout most of the airway from the trachea to the bronchi. The cartilage plates become less prevalent as the airways branch. Eventually, in the last generations of the bronchi, the cartilage plates are found only at the branching points. The bronchi and bronchioles may be distinguished as the bronchi lie proximal to the last plate of cartilage found along the airway, while the bronchiole lies distal to the last plate of cartilage. The bronchioles are the smallest airways that do not contain alveoli. The function of the bronchi and bronchioles is to provide conducting air ways that lead inspired air to the gas-blood interface. However, these conducting airways do not take part in gas exchange because they do not contain alveoli. Rather, the gas exchange takes place in the alveoli which are found in the distal most end of the airways.  
      The mechanics of breathing include the lungs, the rib cage, the diaphragm and abdominal wall. During inspiration, inspiratory muscles contract increasing the volume of the chest cavity. As a result of the expansion of the chest cavity, the pleural pressure, the pressure within the chest cavity, becomes sub-atmospheric with respect to the pressure at the airway openings. Consequently, air flows into the lungs causing the lungs to expand. During unforced expiration, the expiratory muscles relax and the lungs begin to recoil and reduce in size. The lungs recoil because they contain elastic fibers that allow for expansion, as the lungs inflate, and relaxation, as the lungs deflate, with each breath. This characteristic is called elastic recoil. The recoil of the lungs causes alveolar pressure to exceed the pressure at airway openings causing air to flow out of the lungs and deflate the lungs. If the lungs&#39; ability to recoil is damaged, the lungs cannot contract and reduce in size from their inflated state. As a result, the lungs cannot evacuate all of the inspired air.  
      Emphysema is characterized by irreversible damage to the alveolar walls. The air spaces distal to the terminal bronchiole become enlarged with destruction of their walls which deteriorate due to a bio-chemical breakdown. As discussed above, the lung is elastic, primarily due to elastic fibers and tissues called elastin found in the airways and air sacs. If these fibers and tissues become weak the elastic recoil ability of the lungs decreases. The loss of elastic recoil contributes to more air entering the air sacs than can exit preventing the lungs from reducing in size from their inflated state. Also, the bio-chemical breakdown of the walls of the alveolar walls causes a loss of radial support for airways which results in a narrowing of the airways on expiration.  
      Chronic bronchitis is characterized by excessive mucus production in the bronchial tree. 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 this mucus may occlude some small bronchi. Also, the small airways are usually narrowed and show inflammatory changes.  
      In COPD, a reduction in airflow arises as a result of 1) partial airway occlusion by excess secretions, 2) airway narrowing secondary to smooth muscle contraction, bronchial wall edema and inflation of the airways, and 3) reduction in both lung elasticity and tethering forces exerted on the airways which maintain patency of the lumen. As a result of the COPD, the airways close prematurely at an abnormally high lung volume. As mentioned above, in an emphysematous lung there is a decrease of lung parenchyma as there are larger and fewer air sacs. Thus, there is a decrease in the amount of parenchymal tissue which radially supports the airways. This loss of radial traction allows the airway to collapse more easily. As lung recoil decreases and airway closure occurs at higher lung volumes, the residual volume of gas in the lung increases. Consequently, this increased residual gas volume interferes with the ability of the lung to draw in additional fresh gas during inspiration. As a result, a person with advanced COPD can only take short shallow breaths.  
      One aspect of an emphysematous lung is that the flow of air between neighboring air sacs, known as collateral ventilation, is much more prevalent as compared to a normal lung. Yet, while the resistance to collateral ventilation may be decreased in an emphysematous lung the decreased resistance does not assist the patient in breathing due to the inability of the gasses to enter and exit the lungs as a whole.  
      Currently, although there is no cure for COPD, treatment includes bronchodilator drugs, and lung reduction surgery. The bronchodilator drugs relax and widen the air passages thereby reducing the residual volume and increasing gas flow permitting more oxygen to enter the lungs. Yet, bronchodilator drugs are only effective for a short period of time and require repeated application. Moreover, the bronchodilator drugs are only effective in a certain percentage of the population of those diagnosed with COPD. In some cases, patients suffering from COPD are given supplemental oxygen to assist in breathing. Unfortunately, aside from the impracticalities of needing to maintain and transport a source of oxygen for everyday activities, the oxygen is only partially functional and does not eliminate the effects of the COPD. Moreover, patients requiring a supplemental source of oxygen are usually never able to return to functioning without the oxygen.  
      Lung volume reduction surgery is a procedure which removes portions of the lung that are over-inflated. The improvement to the patient occurs as a portion of the lung that remains has relatively better elastic recoil which allows for reduced airway obstruction. The reduced lung volume also improves the efficiency of the respiratory muscles. However, lung reduction surgery is an extremely traumatic procedure which involves opening the chest and thoracic cavity to remove a portion of the lung. As such, the procedure involves an extended recovery period. Hence, the long term benefits of this surgery are still being evaluated. In any case, it is thought that lung reduction surgery is sought in those cases of emphysema where only a portion of the lung is emphysematous as opposed to the case where the entire lung is emphysematous. In cases where the lung is only partially emphysematous, removal of a portion of emphysematous lung increases the cavity area in which the non-diseased parenchyma may expand and contract. If the entire lung were emphysematous, the parenchyma is less elastic and cannot expand to take advantage of an increased area within the lung cavity.  
      Both bronchodilator drugs and lung reduction surgery fail to capitalize on the increased collateral ventilation taking place in the diseased lung. There remains a need for a medical procedure that can alleviate some of the problems caused by COPD. There is also a need for a medical procedure that alleviates some of the problems caused by COPD irrespective of whether a portion of the lung, or the entire lung is emphysematous. The production and maintenance of collateral openings through an airway wall allows oxygen depleted/carbon dioxide rich air to pass directly out of the lung tissue responsible for gas exchange. These collateral openings ultimately decompress hyper inflated lungs and/or facilitate an exchange of oxygen into the blood.  
     SUMMARY OF THE INVENTION  
      This invention relates to devices and methods for altering gaseous flow in a diseased lung. In particular, the inventive method includes the act of improving gaseous flow within a diseased lung by the step of altering the gaseous flow within the lung. A variation of the inventive method includes the act of selecting a site for collateral ventilation of the diseased lung and creating at least one collateral channel at the site. The term “channel” is intended to include an opening, cut, slit, tear, puncture, or any other conceivable artificially created opening. A further aspect of the invention is to locate a site within a portion of a natural airway of the respiratory system of the patient having the diseased lung. The portion of the natural airway selected for the creation of the collateral channels may be, for example, the bronchi, the upper lobe, the middle lobe, the lower lobe, segmental bronchi and the bronchioles.  
      A variation of the invention includes selecting a site for creating a collateral channel by visually examining areas of collateral ventilation. One variation includes visually examining the lung with a fiber optic line. Another example includes the use of non-invasive imaging such as x-ray, ultrasound, Doppler, acoustic, MRI, PET computed tomography (CT) scans or other imaging. The invention further includes methods and devices for determining the degree of collateral ventilation by forcing gas through an airway and into air sacs, reducing pressure in the airway, and determining the reduction in diameter of the airway resulting from the reduction in pressure. The invention further includes methods and devices for determining the degree of collateral ventilation by forcing a volume of gas within the lung near to the airway and measuring pressure, flow, or the return volume of gas within the airway. The invention also includes methods and devices for occluding a section of the airway and determining the degree of collateral ventilation between the occluded section of the airway and the air sacs.  
      An important, but not necessarily critical, portion of the invention is the step of avoiding blood vessels or determining the location of blood vessels to avoid them. It is typically important to avoid intrapulmonary blood vessels during the creation of the collateral channels to prevent those vessels from rupturing. Thus, it is preferable to avoid intrapulmonary or bronchial blood vessels during the creation of the collateral channels. Such avoidance may be accomplished, for example by the use of non-invasive imaging such as radiography, computed tomography (CT) imaging, ultrasound imaging, Doppler imaging, acoustical detection of blood vessels, pulse oxymetry technology, or thermal detection or locating. The avoidance may also be accomplished using Doppler effect, for example transmission of a signal which travels through tissue and other bodily fluids and is reflected by changes in density that exist between different body tissue/fluids. If the signal is reflected from tissue/fluid that is moving relative to the sensor, then the reflected signal is phase shifted from the original signal thereby allowing for detection.  
      Another variation of the inventive device includes a device that detects motion within tissue using Doppler measurements. The device may include a flexible member having a transducer assembly that is adapted to generate a source signal and receive a reflected signal. The transducer assembly may include an acoustic lens which enables the transmission and detection of a signal over a tip of the device.  
      Another variation of the invention includes marking the site after it is located. Accordingly, once marked, a previously selected site can be located without the need to re-examine the surrounding area for collateral ventilation, or the presence or absence of a blood vessel. The marking may be accomplished by the deposit of a remotely detectable marker, dye, or ink. Or, the marking may comprise making a physical mark on the surface of the airway to designate the site. Preferably, the mark is detectable by direct visualization or such imaging methods as radiography, computer tomography (CT) imaging, ultrasound imaging, doppler imaging, acoustical detection, or thermal detection or locating.  
      The invention may also include a user interface which provides feedback once an acceptable site is located. For example, once a site is located a visual or audible signal or image is transmitted to the user interface to alert the user of the location of a potential site. The signal could be triggered once a blood vessel is located so that the site is selected in another location. In another example, the signal may trigger so long as a blood vessel is not located.  
      The invention may include adding an agent to the lungs for improving the imaging. For example, a gas may be inserted into the lungs to provide contrast to identify hyperinflation of the lungs during an x-ray or other non-invasive imaging. For example,  133 Xe (Xenon 133) may be used as the agent. Also, a contrast agent may help in identifying blood vessels during CT scans. Another example includes inserting a fluid in the lungs to couple an ultrasound sensor to the wall of an airway.  
      The invention may also include providing a remotely detectable signal to indicate the presence or absence of any blood vessels at the target site. The invention also includes methods and devices for marking a desired site for the creation of a collateral channel.  
      The invention also includes the act of creating one or more collateral channels within the respiratory system of the individual. The collateral channels may have a cross sectional area anywhere between 0.196 mm 2  to 254 mm 2 . Any subset of narrower ranges is also contemplated. The collateral channels may also extend anywhere from immediately beyond the epithelial layer of the natural airway to 10 cm or more beyond the epithelial layer. The channel or channels should be created such that the total area of the channel(s) created is sufficient to adequately decompress a hyperinflated lung. The channel may be, for example, in the shape of a hole, slit, skive, or cut flap. The channel may be formed by the removal of any portion of the airway wall; e.g., a circumferential or arc-shaped ring of material may be removed to form the channel. Such an excised periphery may be for example, perpendicular or angled with respect to the axis of the airway.  
      Also, it is anticipated that along with any method of creating a collateral channel any loose material or waste generated by the creation of the collateral chalmel is optionally removed from the airway.  
      Another variation for creating the collateral channel is the creation of the airway using electric energy, for example radio frequency. Or, for example, ultrasonic energy, a laser, microwave energy, chemicals, thermal, or cryo-ablative energy may be used to form a collateral channel as well. A feature of these methods often includes creation of a hemostasis in the event that any blood vessel is punctured. For example, use of RF energy provides a hemostasis given a puncture of a vessel by using heat to seal the vessel. Similarly, an ultrasonic scalpel also provides an area of hemostasis in case the vessel is punctured. It is understood that any combination of different methods may be used for forming a single or multiple collateral channels. A variation of the invention includes a limiter for limiting the depth of a collateral channel.  
      Another variation of the inventive device includes combining the doppler catheter described above with a hole-making assembly that is adapted to form collateral channels within tissue. The hole-making assembly may be an RF device and use portions of the tip of the device as RF electrodes, or the hole-making assembly may use ultrasound energy to make the hole. Alternatively, the hole-making assembly may be the transducer assembly described above which may be operated at an intensity which causes the transducer assembly to function as a hole-making device.  
      Another variation of the invention includes the act of inserting an implant or conduit within a collateral channel to maintain the patency of the channel over time during the expiration cycle of the lung. A conduit could, for example, have distal and proximal ends with a wall defining a lumen extending between the ends. The conduit could have, for example, a porous wall permitting the exchange of gasses through the wall. The conduit may, for example, be comprised of a material such as elastomers, polymers, metals, metal alloys, shape memory alloys, shape memory polymers, or any combination thereof. A variation of the invention includes an expandable conduit, either one that is self-expanding, or one that expands in diameter in relation to any applied radial, or axial force. For example, the conduit may be expanded into an opening of the natural airway upon the inflation of a balloon. A variation of the conduit may include the use of flanges or anchors to facilitate placement of the device within an airway. Another variation of the conduit includes placing a one-way valve within the conduit. Another variation includes using a self cleaning mechanism within the conduit to clear accumulating debris.  
      The invention includes the method of feeding a guidewire to a site within the lung, advancing a conduit to the site using the guidewire, and placing the conduit within the lung tissue at the site. The method may include inserting an access device, such as a bronchoscope, within airways of the lung to locate a site within the lung for creation of the collateral channel. The access device could also be used as an access device so that the required devices may be introduced to the site. A catheter having a conduit attached thereto may be advanced over the guide-wire for insertion of the conduit within the collateral channel.  
      The inventive conduit may be, for example, removable or permanent. Also, another variation of the device includes a means for inserting the conduit within a collateral channel. The conduit may be constructed to allow for passage of gasses through its wall, for example, the conduit may have a wall consisting of a braid. A variation of the conduit may be located through an opening in a wall of an airway and engage both an inside and outside of the wall. Another variation of the conduit includes a distal end having a porous member and a proximal end having a grommet member which engages an opening in a wall of the natural airway. Yet another variation of the implant, for example, comprises an expandable conduit-like apparatus which could bridge an opening within a wall of a natural airway. Another variation includes the conduit-like apparatus having a cutting portion exterior to the device wherein expansion of the device pierces the wall of the natural airway and creates a collateral channel.  
      An aspect of the invention is that conduits of varying cross-sectional areas may be placed in various sections of the lung to optimize the effect of the collateral channels.  
      Another variation of the invention includes the application of a cyano-acrylate, fibrin or other bio-compatible adhesive to maintain the patency of a collateral channel. The adhesive may be used with or without the conduit described above. For example, the adhesive may be deposited within the collateral channel to maintain patency of the channel or to create a cast implant of the channel. The inventive act further includes the act of delivering medications such as steroids which have been shown to inhibit the healing process, bronchodilators, or other such drugs which aid in breathing, fighting infection, or recovery from the procedure. The steroids inhibit inflammation and then promote the stabilization of the created channel.  
      Another variation of the inventive process includes promoting the flow of gasses through under-utilized parenchymal inter-conduits, or bypassing restricted airways. It is also contemplated that the gaseous flow may be altered by, for example, making separate inspiratory and expiratory paths. Also, relieving pressure on the external wall of a natural airway may be accomplished to assist the natural airway by maintaining patency during the expiration cycle of the lung. Yet another variation includes creating collateral channels parallel to existing airflow paths, or the existing airflow paths may be increased in cross-sectional area.  
      The invention further includes a modified respiratory airway having an artificially created channel allowing gaseous communication between an exterior of the airway and an interior of the airway.  
      The invention may include an endoscope or a bronchoscope configured to select sites and create collateral channels at those sites. An endoscope or a bronchoscope may also be configured to deploy conduits within the collateral channels. Another variation of the invention includes sizing the device to fit within the working channel of a bronchoscope.  
      The invention also includes methods for evaluating an individual having a diseased lung for a procedure to create collateral channels within an airway of the individual. The invention further includes the method of determining the effectiveness of the procedure.  
      The invention further includes the act of teaching or providing instructions for any of the methods described herein or for using any of the devices describe herein.  
      The invention further includes the method of sterilizing any of the devices or kits described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIGS. 1A-1C  illustrates various states of the natural airways and the blood-gas interface.  
       FIG. 1D  illustrates a schematic of a lung demonstrating a principle of the invention described herein.  
       FIGS. 2A-2C  illustrate devices and methods for determining the degree of collateral ventilation within a lung.  
       FIGS. 3A-3P  illustrate methods of and devices for creating a collateral opening within a natural airway.  
       FIGS. 4A-4B  illustrate a method of folding epithelial tissue through a collateral channel.  
       FIGS. 5A-5D  illustrate devices for detecting blood vessels within tissue.  
       FIGS. 5E-5V  illustrates various devices for detecting blood vessels within tissue where the devices also include hole-making assemblies.  
       FIGS. 6A-6G  illustrate various electrode configurations for the hole-making assemblies of the device.  
       FIGS. 6H-6J  illustrates additional variations of the lens of the present invention.  
       FIGS. 7A-7B  illustrate devices and methods for creating a collateral channel with a device having a hole-making assembly and also preserving the tissue surrounding the collateral channel.  
       FIGS. 7C-7D  illustrate additional electrode configurations for use with a device of the present invention where the structure of the electrodes limits the possible depth of a collateral channel formed by the electrode.  
       FIGS. 8A-8V  illustrate various configuration of implantable conduits.  
       FIGS. 9A-9U ,  10 A- 10 B, and  11 A- 11 C illustrate variations of conduits of the present invention.  
       FIGS. 12A-12I  illustrate variations of methods and devices for deployment of conduits of the present invention.  
       FIGS. 13A-13F  illustrate methods of placing a conduit within tissue. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Prior to considering the invention, simplified illustrations of various states of a natural airway and a blood gas interface found at a distal end of those airways are provided in  FIGS. 1A-1C .  FIG. 1A  shows a natural airway  100  which eventually branches to a blood gas interface  102 .  FIG. 1B  illustrates an airway  100  and blood gas interface  102  in an individual having COPD. The obstructions  104  impair the passage of gas between the airways  100  and the interface  102 .  FIG. 1C  illustrates a portion of an emphysematous lung where the blood gas interface  102  expands due to the loss of the interface walls  106  which have deteriorated due to a bio-chemical breakdown of the walls  106 . Also depicted is a constriction  108  of the airway  100 . It is generally understood that there is usually a combination of the phenomena depicted in  FIGS. 1A-1C . More usually, the states of the lung depicted in  FIGS. 1B and 1C  are often found in the same lung.  
      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.  
      As will be explained in greater detail below, central to this invention in all of its aspects is the production and maintenance of collateral openings or channels through the airway wall so that oxygen depleted/carbon dioxide rich air is able to pass directly out of the lung tissue and into the airways to ultimately facilitate exchange of oxygen into the blood and/or decompress hyper inflated lungs. The term ‘lung tissue’ is intended to include the tissue involved with gas exchange, including but not limited to, gas exchange membranes, alveolar walls, parenchyma and/or other such tissue. To accomplish the exchange of oxygen, the collateral channels allow fluid communication between an airway and lung tissue. Therefore, gaseous flow is improved within the lung by altering or redirecting the gaseous flow within the lung, or entirely within the lung.  FIG. 1D  illustrate a schematic of a lung  118  to demonstrate a principle of the invention described herein. As shown, a collateral channel  112  places lung tissue  116  in fluid communication with airways  100  allowing oxygen depleted/carbon dioxide rich air to directly pass out of the airways  100 . The term channel is intended to include an opening, cut, slit, tear, puncture, or any other conceivable artificially created opening. As shown, constricted airways  108  may ordinarily prevent air from exiting the lung tissue  116 . In the example illustrated in  FIG. 1D , conduits  200  may be placed in the collateral channels  112  to assist in maintaining the patency of the collateral channels  112 . Therefore, it is not necessary to pierce the pleura to improve gaseous flow within the lungs. While the invention is not limited to the number of collateral channels which may be created, it is preferable that 1 or 2 channels are placed per lobe of the lung. For example, the preferred number of channels is 2-12 channels per individual patient.  
      Accordingly, since the invention is used to improve the function of the lungs, a variation of the inventive device may include an endoscope or a bronchoscope configured to locate a site for creating a collateral channel and create the collateral channel. Another variation includes sizing the inventive device to fit within a working channel of an endoscope or a bronchoscope. For the sake of brevity, hereafter, any reference made to an endoscope includes the term bronchoscope.  
      The invention includes assessing the degree of the collateral ventilation taking place in an area of a lung to select a site for creation of a collateral channel. The invention may include locating a site for creation of a collateral channel by visually examining an airway for dynamic collapse. One method of visual examination includes the use of a fiber optic line or camera which may be advanced into the lungs and through the airways. Other variations of visually examining the lung to determine the location of a site for the creation of the collateral channel using non-invasive imaging, including but not limited to radiography, computer tomography, ultrasound, Doppler, and acoustic imaging. Such imaging methods may also be used to determine the amount of collateral channels to be created.  
      Also contemplated in the invention is the addition of various agents to assist during imaging of the airways or lungs. One example includes the use of a non-harmful gas, such as Xenon, to enhance the visibility of hyperinflated portions of the lung during radiological imaging. Another example includes the use of inserting a fluid in the lungs to provide an improved sound transmission medium between the device and the tissue in variations of the invention using ultrasound, acoustic, or other imaging.  
      Another variation of the invention includes methods and devices for triggering a collapse of the airway to determine the degree of collateral ventilation in the lung. One example includes forcing a fluid, such as a gas, air, oxygen, etc., through the airway and into the air sacs. Next, to assess the patency of the airway, the pressure is reduced in the airway. One example of how pressure is reduced in the airway includes evacuating the air in a direction opposite to the air sacs. Constriction of the airway given a drop in pressure may be an indication of collateral ventilation of the lung in that region.  
       FIG. 2A , illustrates a method and device  212  for causing collapse of the airway wall  100 . The device  212  includes a fluid delivery member  214  located at a distal end of the device  212 . The fluid delivery member  214  is configured to deliver a volume of fluid through the airway  100  and into an air sac (not shown). The device  212  may also comprise a probe  216  configured to collect data within the lung. The probe  216  may also simply consist of a channel that transmits signals outside of the lung. Moreover, the fluid delivery member  214  and the probe  216  may not be separate channels. Also, the device  212  may, but does not necessarily, have an occlusion member  218  designed to isolate a section of the airway  100  between the occlusion member  218  and the air sacs (not shown). The occlusion member  218 , which fonns a seal against the airway  100  walls, may provide a partially closed system allowing a more effective search for collateral ventilation between the air sacs (not shown.) The device delivers a burst of fluid, through the fluid delivery member  214  and subsequently uses the probe  216  to measure characteristics such as pressure, flow, or return volume to determine the degree of collateral ventilation. The term fluid is intended to include, air or a gas, such as oxygen, etc. For example, if the air sacs are diseased (as shown in  FIG. 1C ), the forced fluid will escape/disperse through another air sac due to the collateral ventilation of the air sacs. As a result, the probe  216  may fail to record any increase in pressure, volume, flow, or any other characteristic of the fluid at the site. Another variation of the invention includes using the fluid delivery member  214  to add or remove fluid distally to the occluded segment and using the probe  216  to monitor flow or pressure changes in the area. For example, if after adding/removing fluid the pressure in the occluded segment fails to build/drop, the assumption may be made that the gas is being collaterally vented through diseased air sacs.  
       FIG. 2B  illustrates another variation of the invention. In this example, the device  220  comprises a separated probe  216  and gas delivery member  214 . In this variation, the fluid delivery member  214  is configured to pass through a wall of the airway  100  so that fluid may be directly forced into, or pulled out of an air sac  102 .  
       FIG. 2C  illustrates yet another variation of the invention. In this variation, the device  222  may have at least one fluid exchange passageway  224 . The device  222  may force fluid into the airway  100  via the passageway  224 . Then, fluid can be pulled out via the passageway  224 , thus decreasing pressure distally to the device  222 . The decrease in pressure permits fluid to flow out of the airway  100  and away from the air sac (not shown). In this case, if the air sacs surrounding the airway  100  are diseased and collateral ventilation is taking place, then the airway  100  may collapse. A variation of the invention may include an expandable member  218 , such as a balloon, to create a seal against the airway  100  walls. Forming a seal may provide a partially closed system to search for collateral ventilation between air sacs (not shown.) As described above, observation of a collapsing airway  100  may indicate a desired site for creation of a collateral channel.  
       FIGS. 3A-3I  depict various ways of providing openings in the airway wall which may be used as collateral air passageways.  
       FIG. 3A  illustrates an airway  100  having a piercing member  300  and a dilation member  302 . In this example, the piercing member  300  makes an incision (not shown) in the airway  100  wall. Next, the piercing member  300  is advanced into the wall so that a dilation member  302  can expand the incision to thereby provide a collateral channel. In this example, the dilation member  302  is depicted as a balloon. One variation of the invention includes filling a balloon with a heated fluid as the balloon dilates the tissue to form the collateral channel. Use of a heated balloon allows the transfer of heat to the collateral channel for modifying the healing response. However, it is also contemplated that the dilation member may be an expanding wedge (not shown) or other similar device.  
       FIG. 3B  shows a cutting device  304  and an airway  100  having an opening  306  cut from a wall. In this example, a flap  308  is cut from the wall and is attached to an outside or an inside wall of the airway  100 . As will be mentioned below, the flap may be glued, using for instance, fibrin-based or cyano-acrylate-based glues or stapled to that wall.  
       FIG. 3C  illustrates a cutter  304  making an incision  310  in a wall of the airway  100 .  FIG. 3D  illustrates one example of placing the walls of the airway  100  in tension and inserting a blunt instrument  314  into the incision. In this example, the delivery device  312  is flexible and may be shaped to the contour of an airway  100  to provide support for the blunt instrument  314  so that the instrument  314  can advance into the incision. The delivery device  312  is also used to deliver a blunt instrument  314  which expands the original incision. The blunt instrument  314  may have a hooked configuration as needed.  
       FIG. 3E  shows the use of a balloon  320  to dilate a previously formed collateral channel in the airway wall  100 . This procedure may be used variously with other mechanical, chemical, cryo-energy, thermal or RF based penetration systems to expand the size of that previously-fonned opening. It should be noted, that variations of the inventive device described herein using energy to create a collateral channel will require a power supply to be coupled to the active heating element. For sake of convenience, the power supply is not always illustrated in the Figures.  
       FIG. 3F  illustrates a variation of the device  322  having an RF electrode  324 . This variation of the invention uses RF energy to create a collateral channel. The device  322  may be mono-polar or bi-polar. The RF energy throughout this invention is similar to that of a typical RF cutting probe operating between the 300 KHz-600 KHz range.  FIG. 3G-3I  illustrates additional variations of devices of the present invention used to create collateral channels. The devices may use RF energy, either monopolar or bipolar, or the devices may use light, infrared heat, or any of the other methods describe herein. In the variation of  FIG. 3G , the device  328  has an electrode  324  located on a side of the device. This variation of the device  328  automatically limits the depth of the collateral channel as the body of the device  328  remains against an airway  100  wall while the electrode  324  creates a channel.  
       FIG. 3H and 3I  illustrates another variation of a device  330  of the present invention having an electrode  324  located on a front face of the device.  FIG. 3I  illustrates a perspective view of the device  330  with an electrode on the front face  324 . The device  330  may either have an electrode  324  disposed on a front surface of the device  330  or the device may comprise a conductive material with an insulating layer  332  covering the device  330  and leaving an electrode surface  324  exposed. In the variations illustrated in  FIGS. 3G-3I , the size of the electrode may be selected based upon the size of the desired collateral channel.  
      The device of the present invention may also be configured to limit the depth of the collateral channel. In one example,  FIG. 3F , the invention may include a shoulder or stop  326  to limit the depth of the collateral channel. Another example includes graduated index markings on a proximal end of the device or on the distal end so long as they are remotely detectable. Also contemplated is the use of RF impedance measuring. In this example, the use of RF impedance may be used to determine when the device leaves the wall of the airway and enters the air sac or less dense lung tissue.  
       FIG. 3J  illustrates another variation of a device  334  of the present invention adapted to create collateral channels. In this variation, the device  334  includes an elongate body  336  which may have a lumen extending therethrough. The device  334  farther includes a heating element  338  extending from the elongate body  336 . The heating element described herein for the variations of the invention may be the type which actually generates heat in the element, such as, for example, a resistive heating element. Furthermore, the heating element described herein for the variations of the invention may be the type which actually generates heat directly within the tissue, for example, an RF electrode. In any case, the heating element of the present invention shall have a heating surface located on the front surface of the heating element that is adapted to minimize heat in a radial direction from the heating element. Accordingly, the heating element will preferably be a cone, hemispherical, or similar member that is shallow in depth. In one variation, the heating surface will have a depth (as illustrated by depth  341  in  FIG. 3J ) which is less than the diameter of the heating surface. For example, the depth could be less than the radius of the heating surface. As a result of this configuration, heat generated by the heating element is directed towards creating channels or holes. Minimizing heat in a radial direction from the heating element prevents excessive heating of the walls of the collateral channel or hole within the tissue.  
      The heating element  338  shown in  FIG. 3J  includes a heating surface  340  which is located over the front surface of the heating element  338 . The heating element  334  may be any type of heat generating device described herein and is coupled to its respective power supply. In one variation, the heating element  338  comprises an RF electrode. In such a case, the heating element  338  is coupled to an RF generator (not shown). Although not illustrated, a variation of the device includes a heating element which extends through the lumen of the elongate member. The heating element may extend throughout the elongate member or it may extend partially into the elongate member.  
      The variation of the devices described herein may also include insulating surfaces. For example, in  FIG. 3J , the device  334  may have at least one insulating surface  342  located adjacent to the heating surface  340 . The insulating surface  342  shields tissue from heat generated by the heating element  338  as the heating element  338  creates a collateral channel in tissue. The insulating surfaces described herein may be configured to shield tissue from heat generated by the heating element, or, the insulating surface may prevent heat from being generated in the tissue which is adjacent to the insulating surface (e.g., in an RF hole-making device). Each of these materials is selected to have sufficient properties (e.g., low thermal conductivity, non-conductive, etc.). An insulating surface may comprise a ceramic material, such as alumina oxide, zirconia oxide, silicon nitride, silicate, etc. The insulating surface may also comprise a plastic tubing such as Nylon, polyimide, PTFE, Pebax, etc. Other examples include insulating surfaces comprising, for example, an epoxy, or a bio-compatible coating such as paralene. Alternatively, the insulating surface may comprise a combination of the above listed materials. As discussed above, it is noted, that the device may be used without an insulating surface  342 .  
      The device  334  may further include a shoulder  344  located on the elongate body  336  and proximate to the heating element  338 . The shoulder  344  is configured to expand to a diameter greater than a diameter of the elongate body  336 . Accordingly, the shoulder  334  serves as a stop or depth limiter for the device  334  as it creates a collateral channel. In the variation illustrated in  FIG. 3J , the shoulder  344  comprises a balloon, which has a reduced profile (illustrated) and an expanded profile.  FIG. 3K  illustrates the balloon  344  in the expanded profile. The maximum diameter of a shoulder used in any variation of the invention described herein may vary depending upon the application. Currently, it is believed that a shoulder should be greater than 3 mm in diameter. The balloon may be constructed from silicone, urethane, or other such materials. The elongate member of the variations describe herein may be comprised of a nylon, polyethylene, polycarbonate, etc., or a combination thereof.  
      It is noted that a variation of the device of the present invention may have a shoulder  344  comprised of other than a balloon, but is simply a structure which has a diameter greater than a diameter of a heating element on the device. In such a case, referring to the illustration of  FIG. 3K , the shoulder  344  would not be adjustable in a radial direction from the elongate member  336 .  
       FIG. 3L  illustrates another variation of a device  346  of the present invention adapted to create collateral channels. In this variation, the device  346  includes an elongate body  348  which may have a lumen extending therethrough. The device  346  furher includes a heating element  338  extending from the elongate body  348 . Wherein the heating element  338  includes a heating surface  340  which may be located over the front surface of the heating element  338 . As described above, the heating element  338  may be any type of heat generating device described herein and is coupled to its respective power supply. In one variation, the heating element  338  comprises an RF electrode. In such a case, the heating element  338  is coupled to an RF generator (not shown).  
      The variation of the device  346  illustrated in  FIG. 3L  may also includes an insulating surface  342  located adjacent to the heating surface  340 . The insulating surface  342  shields tissue from heat generated by the heating element  338  as the heating element  338  creates a collateral channel in tissue.  
      The device  346  of  FIG. 3L  further includes a shoulder  350  located on the elongate body  348  and proximate to the heating element  338 . As described above, the shoulder  350  is configured to expand to a diameter greater than a diameter of the elongate body  348  allowing the shoulder  350  to serve as a stop or depth limiter for the device  346  as it creates a collateral channel. In the variations illustrated in  FIGS. 3L and 3M , the shoulder  350  is comprised of a plurality of hinged members  352  each of which is adapted to expand in diameter from the expandable member  348 . In this variation, the hinged members  352  each have a living hinge  354  which allows the hinged members  352  to assume an expanded or reduced profile. In the variation depicted in  FIGS. 3L and 3M , the hinged members  352  expand away from the elongate member  348  given relative movement between the elongate member  348  and the heating element  338 . For example, as illustrated in  FIG. 3M , the heating element  338  may be pulled in a proximal direction against the elongate member  348  causing the insulating surface  342  to force the hinged members  352  outwardly. As a result, the shoulder  350  assumes an expanded profile. Although the hinged members  352  are illustrated as being parallel to the lumen of the elongate member  348 , the invention is not limited as such. Moreover, the number of hinged members  352  is not limited to that which is illustrated. It is contemplated that variations of the inventive device may include  2  or more hinged members.  
      In the devices illustrated in  FIGS. 3J-3M , although the heating element is depicted as being spaced from the elongate member, the invention is not limited as such. For example, in variations where the heating element is not slidably located in the elongate member, a device may have a gap between the heating element and the elongate member such that the insulating surface is against or within the elongate member. Moreover, the device may be designed to have a pre-determined gap between the insulating surface and the elongate member. Alternatively, for any of the variations described herein, there may be no gap between the insulating surface and the elongate member.  
       FIGS. 3N-3P  illustrate another variation of the inventive device which is adapted to create collateral channels. In this variation, the heating element  338  is moveably located within an elongate member  360 . At least a portion of the lumen of the elongate member  360  has a reduced opening  362  which is smaller than a diameter of the heating element  338 . As shown in  FIG. 3P , a distal end of the elongate member  360  may be radially adjustable to permit the heating element  360  to move in and out of the lumen. In the variation of the device depicted in  FIG. 3P , the front surface of the elongated member  360  functions as a shoulder  364  when the heating element  338  extends from the front of the elongated member  360 . The distal end of the elongated member  360  may be remotely actuated to expand, or, the distal end may be biased to expand outwardly. In the latter case, the distal end may be restrained, for example, by an outer tubular member  366 . The outer tubular member  336  may also be used to reduce the diameter of the distal end to close against the heating element  338 , as shown in  FIG. 3P . The distal end of the elongated member  360  may be a continuous tubular structure which expands in diameter, or it may be a tubular structure that divided into any number of portions which permit the radial expansion of the distal end. For example,  FIG. 3N  illustrates a front view of the device of  FIG. 3O  in which at least a segment of the elongated member  360  is divided into four portions  368  so that it may be radially adjustable. It is understood that the number of portions  368  illustrated are merely exemplary, as the number may be varied as needed. Furthermore, the elongated member  360  may not be divided into any such portions  368  and instead may be an expandable elastic member comprised of, for example: silicone, urethane, etc.  
      The invention also includes creating a collateral channel by making a single or a series of incisions in an airway wall then folding back the cut tissue through the collateral channel. This procedure allows the surface epithelium which was previously on the inside of the airway wall to cover the walls of the newly formed collateral channel. As discussed herein, promoting growth of the epithelium over the walls of the collateral channel provides a beneficial healing response. The incision may be created by the use of heat or a mechanical surface. For example,  FIG. 4A  illustrates a section of an airway  100  having several incisions  356  forming a number of sections  358  of airway wall tissue the airway  100 . FIG.  4 B illustrates the sections or flaps  358  of the airway wall folded through the collateral channel  112 . Any number of incisions  358  may be made to form any number of sections  358  of airway wall tissue as desired. For example, a plus-shaped incision would result in four sections of tissue that may be folded through a channel. The sections  358  may be affixed with a suture material, an adhesive, or the sections  358  may simply be inserted into surrounding tissue to remain folded through the collateral channel  112 .  
      Another variation of the device includes safety features such as probes to determine the presence of blood. If a probe indicates that a blood vessel is contacted or penetrated, a signal is sent which prevents the channel making device from causing further harm to the vessel. Such a feature minimizes the risk of inadvertently puncturing a blood vessel within the lungs.  
      Although the examples depict mechanically forming a collateral opening, the invention is not limited to such. Alternative methods of forming the opening are contemplated in the use of RF energy, bi-polar, or single pole electrosurgical cutters, ultrasonic energy, laser, microwave, cryo-energy, thermal, or chemicals.  
      Another variation of the invention includes methods and devices for determining whether a blood vessel is in proximity to a potential site. Making this determination prior to creating the channel is advantageous as the risk of puncturing a blood vessel is minimized. It is important that the devices of the present invention do not ‘wander’ resulting in the creation of a collateral channel at a distance from the area originally searched. Such an occurrence may compromise a blood vessel (e.g., puncture, rupture, or otherwise open the blood vessel) even though the step of detecting the location indicated the absence of a blood vessel. In those cases, a device having a stiffer wall provides added benefits. Accordingly, the devices must be flexible to navigate to a target site, yet once they reach the target site the device should be configured to minimize subsequent movement.  
      The present invention includes the use of a device which is able to detect the presence or absence of a blood vessel by placing a front portion of the device in contact with tissue. One variation of the invention includes the use of Doppler ultrasound to detect the presence of blood vessels within tissue. It is known that sound waves at ultrasonic frequencies travel through tissue and reflect off of objects where density gradients exist. In which case the reflected signal and the transmitted signal will have the same frequency. Alternatively, in the case where the signal is reflected from the blood cells moving through a blood vessel, the reflected signal will have a shift in frequency fiom the transmitted signal. This shift is known as a Doppler shift. Furthermore, the frequency of the signals may be changed from ultrasonic to a frequency that is detectable within the range of human hearing.  
      The ultrasound Doppler operates at any frequency in the ultrasound range but preferably between 2 Mhz-30 Mhz. It is generally known that higher frequencies provide better resolution while lower frequencies offer better penetration of tissue. In the present invention, because location of blood vessels does not require actual imaging, there may be a balance obtained between the need for resolution and for penetration of tissue. Accordingly, an intermediate frequency may be used (e.g., around 8 Mhz). A variation of the invention may include inserting a fluid into the airway to provide a medium for the Doppler sensors to couple to the wall of the airway to detect blood vessels. In those cases where fluid is not inserted, the device may use mucus found within the airway to directly couple the sensor to the wall of the airway.  
       FIG. 5A  illustrates a variation of a device  600  adapted to determine the presence of blood vessels as previously mentioned. The device  600  includes a flexible elongate member  604  having a transducer assembly  606 , at least a portion of which is located adjacent to a distal end of the elongate member  604 . Although the elongate member  604  is illustrated as having a lumen, the elongate member  604  may also be selected to be solid, or the elongate member  604  may have a support member (not shown) such as a braid to increase the strength and/or maneuverability of the device. The transducer assembly  606  is adapted to generate a source signal and receive a reflected signal. It may use a single transducer or multiple transducers. For example, at least a first transducer may be used to generate a signal and at least a second transducer may be used to receive the signal.  
      The transducer or transducers may comprise a piezo-ceramic crystal. In the current invention, a single-crystal piezo (SCP) is preferred, but the invention does not exclude the use of other types of ferroelectric material such as poly-crystalline ceramic piezos, polymer piezos, or polymer composites. The substrate, typically made from piezoelectric single crystals (SCP) or ceramics such as PZT, PLZT, PMN, PMN-PT; also, the crystal may be a multi layer composite of a ceramic piezoelectric material. Piezoelectric polymers such as PVDF may also be used. The transducer or transducers used may be ceramic pieces coated with a conductive coating, such as gold. Other conductive coatings include sputtered metal, metals, or alloys, such as a member of the Platinum Group of the Periodic Table (Ru, Rh, Pd, Re, Os, Ir, and Pt) or gold. Titanium (Ti) is also especially suitable. For example, the transducer may be further coated with a biocompatible layer such as Parylene or Parylene C. The transducer is then bonded on the lens. A coupling such as a biocompatible epoxy may be used to bond the transducer to the lens. The transducer assembly  606  communicates with an analyzing device  602  adapted to recognize the reflected signal or measure the Doppler shift between the signals. As mentioned above, the source signal may be reflected by changes in density between tissue. In such a case, the reflected signal will have the same frequency as the transmitted signal. When the source signal is reflected from blood moving within the vessel, the reflected signal has a different frequency than that of the source signal. This Doppler effect permits determination of the presence or absence of a blood vessel within tissue. Although depicted as being external to the device  600 , it is contemplated that the analyzing device  602  may alternatively be incorporated into the device  600 . The transducer assembly of the invention is intended to include any transducer assembly that allows for the observation of Doppler effect, e.g., ultrasound, light, sound etc. The device  600  illustrated in  FIG. 5A  includes a transducer assembly  606  comprising an ultrasound transducer  608  and an acoustic lens  610  that is adapted to refract and disperse a source signal over an outer surface of the lens  610 . The lens  610  is designed such that it interferes and redirects the signals in a desired direction. The lens  610  may be comprised of materials such as dimethyl pentene (plastic-TPX), aluminum, carbon aerogel, polycarbonate (e.g., lexan), polystyrene, titanium, etc. It also may be desirable to place an epoxy between the lens  610  and the transducer  608 . Preferably, the epoxy is thin and applied without air gaps or pockets. Also, the density/hardness of the epoxy should provide for transmission of the signal while minimizing any effect or change to the source signal. The configuration of the transducer assembly  606  permits the lens  610  to disperse a signal over a substantial portion of the outer surface of the lens  610 . The lens  610  also is adapted to refract a reflected signal towards the transducer  608 . Accordingly, given the above described configuration, the device  600  of  FIG. 5A  will be able to detect vessels with any part of the lens  610  that contacts tissue (as illustrated by the line  612 - 612 .) Although the lens  610  is illustrated as being hemispherical, as described below, the lens  610  may have other shapes as well.  
       FIG. 5B  illustrates another variation of the device  614  having a hemispherical shaped ultrasound transducer  618  affixed to an end of a flexible elongate member  616 . The transducer  618  communicates with an analyzing device (not shown) to measure the Doppler effect to determine the location of a blood vessel.  
       FIG. 5C  illustrates another variation of the device  620  including a transducer assembly  622 , at least a portion of which is located adjacent to a distal end of the elongate member  628 . The transducer assembly  622  includes a flat ultrasound transducer  626 , and a cone or wedge-like acoustic mirror  624 . The mirror  624  is adapted to reflect the signal over an area 360° around the device. The angle a of the mirror may be varied to optimally direct the signal as needed.  
       FIG. 5D  illustrates a variation of a device  630  of the present invention fuirther comprising a joint  632  to articulate an end of the device either to make sufficient contact with an area of tissue to be inspected for the presence of a blood vessel, or to navigate within the body to access the area to be inspected.  
      The variations of the invention described herein may also be adapted to use ultrasound energy, for example, high energy ultrasound, to produce openings in or marks on tissue. In such a case, the transducer assembly and acoustic lens also functions as a hole-making or site marking device. In this case, use of ultrasound in a low power operation permits the detection of a blood vessel and location of a site for a collateral channel. Using the same device and switching the operation of the device to a high power ultrasound permits the use of the ultrasound to create a collateral channel.  
       FIG. 5E  illustrates a variation of a device  632  comprising a transducer assembly  634  connected to a flexible elongate member  636 . In this example, the transducer assembly  634  comprises a first transducer  641 , a second transducer  642 , and an acoustic lens  640 . As mentioned above, in variations using alternate transducers  641 ,  642 , one transducer may transmit a signal while the other receives a signal. Also, both transducers  641 ,  642  may simultaneously transmit and receive signals. It is intended that any combination of using the transducers to send and receive signals is contemplated. The device  632  also includes a hole-making assembly  638  for creating a channel in tissue.  FIG. 5E  illustrates the hole-making assembly  638  as an RF wire-like member. As illustrated, the device  632  is connected an RF generator  644  as well as an analyzing device  646  which is adapted to measure the Doppler shift between the generated and reflected signals.  
       FIG. 5F  illustrates the device  632  of  FIG. 5E  where the hole-making assembly  638  is retracted within the device  632 , in this case within the elongated member  636 .  
       FIG. 5G  illustrates another variation of a device  648  where a hole-making assembly  650  is exterior to a transducer assembly  606 . The hole-making assembly  650  may be either an RF device or a mechanical device that simply cuts the tissue. For example, the hole making assembly  650  can be a hypotube placed over the transducer assembly  606 . In this variation of the device  648 , the transducer assembly  606  may be moveable within the hole-making assembly  650 , or the hole-making assembly  650  may be moveable over the transducer assembly  606 . In either case, the transducer assembly  606  may be advanced out of the hole-making assembly  650  to determine the presence of a blood vessel. If no blood vessel is found, the transducer assembly  606  may be withdrawn into the hole-making assembly  650  allowing the hole-making assembly  650  to create a channel in the tissue either by mechanically cutting the tissue, or by using RF energy to create the channel.  FIG. 5H  illustrates a view taken along the line  5 H in  FIG. 5G .  
       FIG. 5I  illustrates another version of a device  652  of the present invention wherein the device has a transducer assembly  654  with an opening  658  through which a hole-making assembly  656  may extend.  FIG. 5J  illustrates the hole-making assembly  656  extended through the transducer assembly  654 . The hole-making assembly  656  may comprise RF electrodes or needle-like members which puncture the tissue to create the channels.  
       FIG. 5K  illustrates a variation of a device  666  of the present invention where a tip  660  of the device has a conductive portion allowing the tip to serve as both an acoustic lens and an RF electrode. In such a case, the tip  660  is comnected to an RF generator  644  for creating channels within tissue and a transducer  662  is placed in communication with an analyzing device  646  that is adapted to measure the Doppler shift between generated and reflected signals. In this variation, the tip  660  is separated from the transducer  662 , but both the tip  660  and transducer  662  are in acoustic communication through the use of a separation medium  664 . The separation medium  664  transmits signals between the tip  660  and the transducer  662 . The spacing of the transducer  662  from the tip  660  serves to prevent heat or RF energy from damaging the transducer  662 . It is intended that the spacing between the transducer  662  and tip  662  shown in the figures is for illustration purposes only. Accordingly, the spacing may vary as needed. The separation medium must have acceptable ultrasound transmission properties and may also serve to provide additional thermal insulation as well. For example, an epoxy may be used for the separation medium.  
       FIG. 5L  illustrates a variation of a device  680  of the present invention wherein the transducer assembly  670  comprises a tip  672 , an ultrasound coupling medium  674 , a transducer  676 , and an extension member  678 . In this variation of the invention, the tip  672  of the device serves as an acoustic lens and also has conductive areas (not shown) which serve as RF electrodes. As shown in  FIG. 5M , the tip  672  may extend from the device  680  and separate from the transducer  676 . Separation of the tip  672  protects the transducer  676  from heat or RF energy as the tip  672  creates a channel in tissue. The extension member  678  may serve as a conductor to connect the tip  672  to an RF energy supply (not shown). When the tip  672  of the device  680  is being used in an ultrasound mode, the tip  672  may be coupled to the transducer  676  via the use of an ultrasound coupling medium  674 . Any standard type of ultrasound gel material may be used, also highly formable silicone may be used. It is desirable to use a fluid boundary layer (such as the gel) which may be permanent or temporary. In those cases where the boundary layer is temporary, subsequent applications of the boundary layer may be necessary.  
       FIG. 5N  illustrates another variation of a device  682  of the present invention having a tip  684  and transducer  686  that are separable from each other. Again, the tip  684  may include conductive areas and serve as both an RF electrode (not shown) as well as an acoustic lens. As shown in  FIG. 5N , the tip  684  may be separable from the transducer  686  when creating a channel to protect the transducer  686  from heat or RF energy. The tip  684  may be placed in contact with the transducer  686  for operation in an ultrasound mode, or the device  682  may contain a separation medium  688  which permits acoustic coupling of the transducer  686  with the tip  684  when separated.  
       FIG. 5Q  illustrates another variation of the inventive device  740  which is able to detect the presence or absence of a blood vessel using Doppler ultrasound and which is also able to create collateral channels within the lung tissue. The device includes a transducer adapted to generate a source signal and receive a reflected signal with a portion of the assembly located adjacent to the distal end of the elongate member  748 . The transducer assembly may include at least one ultrasound transducer  742  and a lens  744  which enables the transmission and detection of a signal over a tip of the device  740 . The device  740  further includes at least one heating element  746  located at a distal end of the lens  744 . The heating element permits the device to create collateral channels. In the variation depicted in  FIG. 5Q , the heating element  746  comprises a plurality of openings  750  which allow for passage of ultrasound signals through the heating element  746 . Accordingly, the device  740  may use the transducer assembly to confirm the absence of a blood vessel at a particular site, and then use the heating element to create a collateral channel.  FIG. 5P  illustrates a front view of the device  740  of  FIG. 5P  further illustrating the heating element  746  with a number of openings  750 . The number of openings  750  on a heating element is not limited to that shown. Moreover, the heating element  746  may comprise a mesh having a plurality of openings.  
       FIG. 5R  illustrates a variation of the inventive device wherein the transducer assembly is moveable within a lumen of the elongate member  748 . As described elsewhere herein, the transducer assembly may be moved when the heating element  746  is activated to create collateral channels.  FIG. 5R  depicts the device  740  as being connected to a power supply  752  and to an ultrasound controller device  754 .  
       FIG. 5S  illustrates another variation of a device of the present invention where the transducer assembly comprises at least one transducer  608  and an acoustic lens  610  that is adapted to refract and disperse a source signal over an outer surface of the lens  610 . As described herein, the lens  610  is designed such that it interferes and redirects the signals in a desired direction. As illustrated, the transducer assembly is coupled to an ultrasound controller device  754 . The device  756  further includes a heating element  758  located distally of the lens  610 . The heating element  758  is coupled to a power supply  752 . Although the heating element  758  is illustrated as extending into the elongate member  604  of the device  756 , the device is not limited as such. In one variation of the invention, the heating element  758  may be configured in a “U” shape. With this configuration, after the device  756  penetrates tissue, rotation of the device  756  penmits coring of the tissue to create a collateral channel. However, the heating element  758  may be configured in other shapes as needed.  
       FIGS. 5T-5V  illustrate another variation of the inventive device  770  which is adapted to detect the presence or absence of a blood vessel using Doppler ultrasound and which is also able to create collateral channels within the lung tissue. In this variation, the device  770  includes a detection device  600  adapted to determine the presence of blood vessels, as discussed above, is moveably located within an elongate member  762 . At least a portion of the lumen of the elongate member  762  has a reduced opening  764  which is smaller than a diameter of the detection device  600 . It is noted, that the detection device may be any detection device described herein.  
      As shown in  FIG. 5V , a distal end of the elongate member  762  may be radially adjustable to permit movement of the detection device  600  in and out of the lumen. In the variation of the device depicted in  FIG. 5V , a heating element  760  is placed on a distal end of the elongate member  762 . Accordingly, when the detection device  600  is advanced out of the elongate member  762 , the detection device  600  may determine the presence or absence of a blood vessel. Once a suitable location is found for the creation of a collateral channel, the detection device  600  is retracted into the elongate member  762 , thereby positioning the heating element  760  to create a collateral channel. Optionally, as the heating element  760  generates heat as it creates the collateral channel, the detection device  600  may be moved proximally to minimize the possibility of any damage resulting from the generated heat. It should be noted that the elongate member may contain a shoulder to limit the depth of the collateral channel. Alternatively, in another variation of the invention, the detection device  600  may be configured to create a collateral channel via ultrasound energy. In such a case, no heating element is required and the expandable distal end of the elongate member  762  may serve as a shoulder to limit the depth of the collateral channel. In any case, as shown in  FIG. 5U , when the device  770  is advanced through the airways of a lung, the detection device  600  may remain within the elongate member  762 .  
      As with similar embodiments described herein, the distal end of the elongated member  762  may be remotely actuated to expand, or, the distal end may be biased to expand outwardly. In the latter case, the distal end may be restrained, for example, by an outer tubular member  766 . The outer tubular member  766  may also be used to reduce the diameter of the distal end to secure against the detection device  600 , as shown in  FIG. 5V . The distal end of the elongated member  762  may be a continuous tubular structure which expands in diameter, or it may be a tubular structure that divided into any number of portions  768  which permit radial expansion of the distal end. For example,  FIG. 5U  illustrates a front view of the device of  FIG. 5T  in which at least a segment of the elongated member  762  is divided into four portions  768  so that it may be radially adjustable. It is understood that the number of portions  768  illustrated are merely exemplary, as the number may be varied as needed. Furthermore, the elongated member  762  may not be divided into any such portions  768  and instead may be an expandable elastic member.  
       FIGS. 6A-6F  illustrate variations of RF electrode tip  690  configurations for use with the present invention. As illustrated, the electrodes may be placed around a circumference of a tip, longitudinal along a tip, spirally along a tip, or a combination thereof. The electrodes  692 ,  694  may be used with a device having an acoustic lens or the electrodes may be employed solely as an RF hole-making device. While the variations illustrated in  FIGS. 6A-6F  show bipolar RF devices, the invention may also use a single electrode (monopolar.) The tip  690  may contain a first electrode  692  separated from a second electrode  694  by an electrical insulator  696  (e.g., ceramic, or plastic insulator). In variations of the device where electrodes are positioned on an acoustic lens, a sufficient amount of surface area of the lens must remain uncovered so that sufficient coupling remains for transmission of a signal between the lens and tissue.  FIG. 6G  illustrates a co-axial variation of a bi-polar RF tip having a first electrode  692 , a second electrode  694 , and an insulator  696 .  
       FIGS. 6H-6J  illustrates additional variations of the lens of the present invention.  FIG. 6H  illustrates a device  724  with an acoustic lens  726  having an oblate spheroid shape.  FIG. 6I  illustrates a device  728  with an acoustic lens  730  having a prolate spheroid shape.  FIG. 6J  illustrates a device  732  having a conical-shaped acoustic lens  734 . These variations are only intended to illustrate variations of the lens. It is contemplated that the shape of a lens may not follow a mathematical description such as conical, prolate, oblate or hemispherical. The design of the shape relates to the distribution pattern of the signal over the lens. The shapes can affect the distribution pattern by making it wider or narrower as needed. In any case, the lens is of a shape that provides coverage over the front face of the device.  
       FIG. 7A  illustrates a variation of the invention where a device  700  includes a heat-sink member  702 . The heat-sink member  702  may preserve surround tissue during creation of the collateral channel. Or, the heat-sink member  702  may be a section of conductive material or a balloon. The heat-sink member  702  may be in fluid communication with a lumen  704  that provides a fluid, such as saline, that conducts heat away from the area surrounding the channel.  
       FIG. 7B  illustrates another variation of a device  710  having a fluid delivery assembly  706  which assists in preserving surrounding tissue while a channel is being created. The fluid delivery assembly  706  may spray, mist, or otherwise apply fluid  708  to the area surrounding the channel. For example, cooled saline may be applied to the area to prevent excessive heating of the target area.  
      The invention includes the use of hole-making assembly on the side of the device with a transducer assembly on the tip of the device. For example,  FIG. 7C  illustrates a variation of an RF electrode  712  for use with the present invention. The electrode  712  may be a protrusion extending from a conductive member  716  that is covered with an insulating material  714 . In this variation, the electrode  716  limits the depth of the channel due to the amount of material extending from the conductive member  716 . The conductive member  716  may be connected to a source of RF energy (not shown) or may use another heating element (not shown).  FIG. 7D  illustrates another variation of an electrode configuration. In this variation, the electrode comprises a spherical member  718  extending from an elongate member  722 . The electrode  718  is retractable through the elongate member  722  by use of an actuator  720 . The actuator  720  may be conductive and connected to a source of RF energy to conduct energy through the electrode  718 . Again, the design of the electrode  718  limits the depth of penetration of the electrode  718  while creating a channel in tissue. The electrodes described herein may also be used in conjunction with a device having a Doppler arrangement.  
      Also, a variation of the invention contemplates the delivery of drugs or medicines to the area of the collateral opening. Also contemplated is the use of a fibrin, cyano-acrylate, or any other bio-compatible adhesive to maintain the patency of the opening. For example, the adhesive could be deposited within the collateral chamnel to maintain patency of the channel or to create a cast implant of the channel. The adhesive could also coat the channel, or glue a flap to the wall of the airway. Also, the use of a bioabsorbable material may promote the growth of epithelium on the walls of the conduit. For example, covering the walls of a channel with small intestine submucosa, or other bioabsorbable material, may promote epithelium growth with the bioabsorbable material eventually being absorbed into the body.  
       FIG. 8A  illustrates an implant or conduit  500  placed within a natural airway  100 . As shown, the airway  100  has a portion of its wall removed, thereby providing a collateral opening  112  within the airway  100 . The implant  500  typically has a porous structure which allows gasses to pass between the airway and the chamnels  112  and into the lung. Moreover, the structure of the insert  500  also maintains patency of the airway  100  and the channel  112 .  
      Any variation of a conduit described herein may comprise a barrier layer which is impermeable to tissue. This aspect of the invention prevents tissue in-growth from occluding the channel. The barrier layer may extend between the ends of the body or the barrier layer may extend over a single portion or discrete portions of the body of the conduit.  
       FIG. 8B  illustrates an conduit  500  having an expandable structure within an airway  100 . Usually, the conduit  500  has a porous wall that allows the passage of gasses through the wall. The conduit  500  is delivered via a delivery device  502  which may also contain an expandable member (not shown) which expands the conduit  500 . As shown in  FIG. 8C , the conduit may have piercing members  504  attached on an outer surface which enable the conduit  500  to create an incision within the airway  100 .  
       FIG. 8C  illustrates the conduit  500  after being expanded by an expandable member  506 , e.g. a balloon device, an expandable mechanical basket, or an expandable wedge. In this example, the conduit  500  expands through the walls of the airway  100  at sections  508 . In this variation, the conduit  500  is lodged within the walls of the airway  100 .  
       FIG. 8D  illustrates a grommet-like insert  503  where the lumen of the insert  503  extends longitudinally through the collateral channel. In this example, an expanding member  501 , e.g., a balloon, an expanding mechanical basket, or the like is used to secure the conduit  503  within the collateral channel.  
      Although not illustrated, the invention includes conduits having a length to diameter ratio approximately 1:1. However, this ratio may be varied as required. The cross-section of an implant may be circular, oval, rectangular, elliptical, or any other multi-faceted or curved shape as required. The cross-sectional area of an implant  500  may be between 0.196 mm 2  to 254 mm 2 .  
      The conduit may also be any device capable of maintaining a patent opening, e.g., a plug, that is temporarily used as a conduit and then removed after the channel has healed in an open position. In another variation the plug may be a solid plug without an opening that is either bio-absorbable or removable. In such a case, the plug may be placed within an opening in tissue and allow the tissue to heal forming a collateral channel with the plug being ultimately absorbed into the body or removed from the body.  
      Another variation of the conduit is illustrated in  FIG. 8E . In this example the conduit  510  comprises a cone  514  with a grommet  512  for attachment to a wall of the airway  100 . The cone  514  may be porous or have other openings  516  to facilitate the passage of gas through the collateral channel. In the event that the distal opening of the cone become occluded, the porous cone permits the continued exchange of gasses between the collateral channel and the natural airway.  
      Another variation of the conduit is illustrated in  FIG. 8F . For example, the conduit  518  may be configured in a ‘t-shape’ with a portion  520  of the conduit extending through the collateral channel. Again, the conduit  518  may be constructed to have a porous wall to allow gas exchange through the wall. The conduit may be configured in a variety of shapes so long as a portion of the conduit extends through the collateral channel. The portion may be formed into a particular shape, such as the ‘t-shape’ described above, or, the portion may be hinged so that it may be deployed within the channel. In such a case, a portion of a wall of the conduit may have a hinge allowing the wall of the conduit to swivel into a channel.  
      Yet another variation of the conduit is found in  FIG. 8G . In this example, the conduit  522  is constructed with a geometry that reduces the chance that the conduit  522  will migrate within the airway  100 .  
       FIG. 8H  illustrates an example of a conduit  524  having an asymmetrical profile. The conduit  524  may have a flange  526  at either or both ends of the body  528 . Although not shown, the flange  526  may have a cone-like profile to facilitate placement within an airway. As illustrated in  FIG. 8I , the asymmetrical profile of the conduit  524  assists in preventing obstruction of the airway.  
       FIG. 8J  illustrate a variation of the conduit  530  having a self-cleaning mechanism. In this example, the self cleaning mechanism is a floating ball bearing  532 . The ends of the conduit  530  have a reduced diameter  534  which prevents the bearing  532  from escaping. As gas passes through the conduit  530 , the bearing  532  moves about the conduit  530  clearing it of debris. The shape of the bearing  532  and the size and shape of the reduced diameter  534  may be varied to optimize the self-cleaning effect of the device.  
       FIG. 8K and 8L  illustrate another variations of a self-expanding conduit  536 . In this example, as shown in  FIG. 8K , the conduit  536  may be constructed from a flat material  538  having a spring or springs  540 . As shown in  FIG. 8L , the conduit  536  is formed by rolling the assembly. The spring  540  provides an expanding force against the material  538 . The conduit  536  may also be constructed so that the flat material  538  is resilient thus eliminating the need for springs  540 .  
       FIG. 8M  illustrates another variation of an expandable conduit  542  constructed from a braided material. The conduit  542  may be constructed so that the diameter is dependent upon the length of the device  542 . For example, the diameter of the device  542  may decrease as the length is stretched, and the diameter may increase as the length of the device  542  is compressed. Such a construction being similar to a ‘finger cuff’ toy.  
       FIGS. 8N-8P  illustrate another variation of a groimet-type conduit.  FIG. 8N  illustrates a conduit  544  having expandable ends  546 . In one variation the ends  546  of the device  544  may flare outwards as illustrated in  FIG. 5P .  FIG. 8N  illustrates another variation of the device  544  in which the ends  546  compress in length to expand in diameter.  
       FIGS. 8Q and 8R  illustrate variations of a conduit having an anchor. In  FIG. 8Q , the conduit  548  has an anchor  550  at a distal end of a hollow plug  540 . The anchor  550  may be tapered to facilitate entry into the airway  100  wall or may have another design as required. The anchor  550  also contains ventilation openings  552  to facilitate gas exchange through the device.  FIG. 8R  illustrates another variation of the device.  
       FIG. 8S  illustrates a variation of a conduit  561  having flanges  563  at either end to assist in placement of the conduit within an airway wall (not shown). The ends of the conduit  565  may be tapered to ease placement through a collateral channel. The conduit has an opening  565  to facilitate passage of air. To simplify construction, the conduit  561  may be constructed from a biocompatible material, such as stainless steel, or plastic.  
       FIG. 8T  illustrates a variation of the invention having multiple openings for gas flow. The conduit  560  has a first hollow end  564  which can extend through a wall of the airway  100  and a second hollow end  566  which can remain parallel to the airway  100 . This example also includes an opening  562  which allows gas to flow through the airway  100 .  
       FIG. 8U  illustrates a variation of the device having a one-way valve  570 . The valve  570  allows the conduit  568  to permit exhaust of the air sac but prevents the conduit  568  from serving as another entrance of gas to the air-sac. The valve  570  may be placed at ends of the conduit or within a lumen of the conduit. The valve  570  may also be used as bacterial in-flow protection for the lungs.  
       FIG. 8V  illustrates another variation of a conduit  572 . In this variation, the conduit  572  maybe a sponge material, or constructed of an open cell material  574 , which allows air flow through the material. Or, the conduit  572  may have lumens  576  which allow flow through the conduit  572 . To assist the conduit  572  in remaining within a channel, the conduit material may be selected such that it expands as it absorbs moisture. Also, the sponge material/open cell material may be bio-absorbable to allow for temporary placement of the conduit  572 .  
       FIGS. 9A-9F  illustrate another variation of a conduit  800  of the present invention. The conduit  800  has a center section  802  having extension members  804  located at either end of the center section  802 . The center section  802  illustrated is tubular but may be of any other shape as needed for the particular application. The conduit of the invention has a passageway extending between the ends of the conduit suited for the passage of air. The variation of the conduit  800  illustrated in  FIG. 9A  has a center section  802  comprising a mesh formed from a plurality of ribs  806 .  FIG. 9A and 9B  illustrate the conduit  800  in a reduced profile while  FIG. 9C and 9D  illustrate the conduit  800  in an expanded profile after expansion of the center section  802  of the conduit  800 . As shown in  FIGS. 9E and 9F , each free end  808  of each extension member  804  is unattached to the center section  802  and is bendable about the respective end of the center section  802  to which it is attached. Accordingly, once a conduit  800  is placed within a collateral channel (not shown), the extension members  804  are bent about the end of the center section  802  and form a cuff or grommet which assists in keeping the conduit  800  within a collateral channel. Accordingly, the cross section and number of extension members  804  located about either end of the conduit  800  may be selected as necessary to assist in placement and securing of the conduit  800  within a channel.  
      The conduits described herein may have a fluid-tight covering, as discussed below, about the center section, the extension members, or the entire conduit. Also, the conduit may be designed to limit a length of the center section to less than twice the square root of a cross sectional area of the center section when the center section is in the expanded profile.  
       FIGS. 9G-9I  illustrates another variation of a conduit  812  for use with the invention. In this variation, the conduit  812  is formed from a rolled sheet of material  810 . The rolled sheet  810  may be heat treated to preserve the shape of the conduit  812  or the sheet  810  may simply be rolled to fonn the conduit  812 . In those cases where the sheet of material  810  comprises a shape-memory alloy, it is desirable to process the material  810  so that it exhibits super-elastic properties at or above body temperature.  
       FIG. 9G  illustrates a variation of extension members  820  for use with a conduit (not shown) of the present invention. In this variation, the extension members  820  have an attachment  822  between adjacent extension members  820 .  FIG. 9H  illustrates the extension members  820  as the conduit (not shown) is expanded and the extension members  820  are bent on the conduit. The attachment  822  assists in preventing the extension members  820  from deviating from a preferred position. As illustrated in  FIG. 9I , the conduit  826  may have cut or weakened sections  824  to facilitate expansion of the conduit  826  and bending of the extension members in a desired manner (as shown by the section of  828 ).  
       FIGS. 9J-9K  illustrate various additional cross sectional designs of conduits.  FIG. 9J  illustrates a possible conduit design  830  having extension members  834  attached to a center section  832 .  FIGS. 9K and 9L  illustrate additional variations of conduit designs. As illustrated in  FIGS. 9K and 9L , the extension members  840 ,  846  and center sections  838 ,  844  are designed to form a diamond pattern upon expansion of the conduit.  FIG. 9K  further illustrates a variation of an extension member  840  having an opening  841  to facilitate tissue in-growth and thereby secures placement of the conduit.  FIG. 9M  illustrates an expanded conduit  848  having the diamond pattern referred to above. The conduit  848  also contains a fluid-tight barrier  851  on the center section  850  of the conduit  848 . Although not illustrated, fluid-tight barrier may be placed throughout a conduit. Another feature of the variation of  FIG. 9M  is that the extension members have a diamond pattern construction, this construction assists in maintaining alignment of the extension members allowing for a preferred aligned expansion of the extension members.  
       FIGS. 9n-9O  illustrate another variation of a conduit  860  of the present invention. In this variation, the conduit design  854  may have extension members  856  at only one end of the conduit  860 . In this variation, the center section of the conduit may comprise a body portion  858 . The conduit  860  may have a covering about a portion of the conduit  860 . The covering may extend throughout the length of the conduit  860  or it may be limited to a portion of the conduit  860 . As illustrated in  FIG. 9O , when expanded, the conduit  860  may form a reduced area  858  near the extension members  856 . As mentioned above, the conduit cross section  854  may be designed such that the a diamond pattern is formed upon expansion of the conduit  860 , as illustrated in  FIG. 9O .  
       FIG. 9P  illustrates a sheet of material  810  having extension members  814  extending from either end of the sheet  810 . Although the sheet  810  is illustrated to be solid, a conduit may be formed from a sheet having openings within the center section of the sheet.  FIG. 9Q  illustrates the conduit  812  where the rolled sheet  810  comprises a center section  818  of the conduit  812  and the extension members  814  from either end of the center section  818 . As illustrated in  FIG. 9Q , the sheet  810  may be overlapped for a reduced profile and expanded into an expanded profile.  FIG. 9R  illustrates a free end  816  of each extension member  814  as having been bent away from a central axis of the conduit  812 . As with any variation of a conduit of the present invention, the extension members  814  of the conduit  812  may be bent away from a central axis of the conduit  812  up to 180° with respect to the central axis. As mentioned above, the cross section and number of extension members  814  located about either end of the conduit  810  may be selected as necessary to assist in placement and securing of the conduit  810  within a channel.  
      In those cases where the conduit  812  of  FIG. 9Q  comprises a non-shape memory alloy the conduit  812  will be actively mechanically expanded. In those cases where the conduit  812  is comprised of a shape memory alloy, such as a super-elastic alloy, the conduit  812  may be pre-formed to assume a deployed shape which includes a grommet formed by extension members  814  and an expanded center section  818 , such as the shape illustrated in  FIG. 9R . Next, the super-elastic conduit  812  may be restrained or even rolled into the shape illustrated in  FIG. 9Q . Because the conduit  812  is formed of a super-elastic material, no plastic deformation occurs. When the super-elastic conduit  812  is then placed within a collateral channel, the conduit  812  may naturally resume its pre-formed, deployed shape.  
       FIG. 9S  illustrates another variation of a conduit  862  having a first portion  864  and a second portion  866  and a passageway  868  extending therethrough. The first portion  864  may be a conduit design as described herein. In particular, the first portion  864  is configured to secure the conduit  862  to the airway wall  100 . Accordingly, the first portion  864  may or may not have a center that is expandable. The walls of the first portion  864  may be fluid-tight (either through design, or a fluid tight covering) to prevent tissue in-growth through the collateral channel. Alternatively, the first portion  864  may be partially fluid-tight to facilitate tissue in-growth to improve retention of the conduit  862  to the airway wall  100 . However, in the latter case, the first portion  864  should be designed to minimize tissue in-growth within the channel to prevent substantial interference with airflow through the conduit  864 . As with the first portion  864 , the walls of the second portion  866  of the conduit may or may not be fluid-tight. If the second portion  866  is not fluid-tight, the larger area provides for improved airflow from lung tissue through the passageway  868  and into the airway. The second portion  866  may also be designed to be partially fluid-tight to encourage airflow through the conduit  862  but reduce the probability of blockage of the conduit  862 .  
       FIGS. 9T-9U  illustrate another variation of a conduit  870 . For example, the conduit  870  may be formed from a tube that is slit to form extension members at a first portion  872  and second portion  876  with a center section  874  between the portions. The conduit  870  may be expanded as shown in  FIG. 9U  such that the first  872  and second  876  portions maintain the center portion  874  in a collateral channel in an airway wall. The center section  874  may or may not be expandable.  
       FIG. 9U  illustrates the second portion  876  of the conduit  870  to expand in its center, however, the conduit  870  may be designed in other configuration as well (e.g., expanded to have a larger diameter at an end opposite to the center section  874 .) However, a central aspect of this design is that the second portion  870  provides a large area in the lung tissue to permit a larger volume of air to pass fiom the lung tissue into the conduit  870 . This design has an added benefit as the second portion  876  cannot be easily blocked by flaps of parenchyma tissue. A simple variation of the conduit  870  may be constructed from a metal tube, such as  316  stainless steel, titanium, titanium alloy, nitinol, etc. Alternatively, the conduit may be formed from a rigid or elastomeric material.  
      The conduits described herein may be comprised of a metallic material (e.g., stainless steel), a shape memory alloy, a super-elastic alloy (e.g., a NiTi alloy), a shape memory polymer, a polymeric material or a combination thereof. The conduit may be designed such that its natural state is an expanded state and it is restrained into a reduced profile, or, the conduit may be expanded into its expanded state by a variety of devices (e.g., a balloon catheter.) The conduit described herein may be manufactured by a variety of manufacturing processes including but not limited to laser cutting, chemical etching, punching, stamping, etc.  
      The conduits described herein may be coated with an elastomer, e.g., silicone, polyurethane, etc. The coatings may be applied, for example, by either dip coating, molding, or liquid injection molding (for silicone). Or, the coating may be a tube of a material and the tube is placed either over and/or within the conduit. The coating(s) may then be bonded, crimp, heated, melted, or shrink fit. The coatings may also be placed on the conduit by either solvent swelling applications or by an extrusion process. Also, a coating of may be applied by either wrapping a sheet of PTFE about and/or within the conduit, or by placing a tube about and/or within the conduit and securing the tubes.  
      Another variation of the invention is illustrated in  FIGS. 10A-10B . In this variation, a conduit of the present invention contains a filler material between the openings of the ribs or mesh. For example,  FIG. 10A  illustrates a partial plane view of a conduit  880  having a plurality of ribs or a mesh structure  882  as previously described. The conduit  880  includes placing a filler material  884  between each of the ribs/opening of the mesh. A covering  886  is then placed over the ribs/mesh  882  and filler material  884 . The covering  880  encapsulates the structure of the conduit  880  and covers the outer surface of the conduit  880  and the interior wall of the lumen or passageway of the conduit  880 .  FIG. 10B  illustrates a partial sectional view of the conduit  880  of  FIG. 10A .  FIG. 10B  illustrates the mesh  882  with filler material  884  adjacent to the mesh  882  and an outer covering  886  encapsulating the mesh  882  and filler material  884 . It is noted that the filler material  884  and covering  886  may be placed entirely throughout a conduit. Alternatively, the filler material  884  and covering  886  may be placed partially over a conduit as needed. It is believed that the addition of filler material to a conduit of the present invention provides a unifonn thickness of the covering which results in uniform and consistent stretching of the covering. Some various examples of filler material are, for example, wax, silicone, and urethane. The covering may consist of, for example, silicone, urethane, or similar materials.  FIG. 11A-11C  illustrate another variation of a conduit  888  of the present invention. In this variation, the conduit comprises a continuous phase material  896  that is weak enough to expand but strong enough to keep a particular size and shape upon expansion of the conduit  888 . Some examples of a continuous phase material are polytetrafluoroethylene and polypropylene. These materials exhibit plastic deformation without exhibiting tears or breaches in their surfaces when expanded. These materials may be selected to have a properties (e.g., modulus, yield stress, etc.) which permit expansion of the conduit into a desired shape and retention of that shape. To further assist in controlling the expansion and shape of the installed conduit  888 , the conduit may have weakened sections that permit the ends of the conduit to bend as desired. For example, the wall thickness of the conduit  888  may vary as illustrated. As shown in  FIG. 11A , the wall thickness of the material  896  between the extension members  890  and the center section  892  may be less than a thickness of the wall section of the material  896  at the center section  892 . As illustrated, if an outwardly radial force is applied to the extension members  890 , such a configuration results in a higher bending stress at the area of reduced wall thickness  894 . As a result, and as illustrated in  FIG. 11B-11C , the extension members  890  expand in a predetermined manner.  
      As mentioned above, the number of and cross sectional area of the extension members on a conduit may be selected as needed for the particular application. Also, the extension members may be bent such that they anchor into the tissue thereby securing placement of the conduit. Or, the extension members or the center section may contain barbs or other similar configurations to better adhere to the tissue. Moreover, the orientation of the extension members may vary as well. For example, the extension members may be configured to be radially expanding from the center section, or they may be angled with respect to a central axis of the conduit. Another variation of the invention includes a radioactive conduit which inhibits or prevents the growth of tissue within the conduit.  
      Although the conduits of the current invention have been described to contain expandable center sections, the invention is not necessarily limited as such. Instead, the design of the conduit may require extension members on the ends of a conduit with a non-expandable center section.  
       FIGS. 12A-12D  illustrate a conduit  900  of the present invention. The deployment of the conduit  900  is intended to show an example of a possible means of deployment only. Accordingly, the inventive conduit may be delivered at an angle via an articulating or jointed device, the conduit may be delivered on a device that is adapted to locate and create the collateral channel, or the conduit may be delivered on a device having other features as needed for the particular application.  
       FIG. 12A  illustrates the conduit  900  being delivered to a collateral channel in an airway wall  114  via a delivery device (e.g., a balloon catheter  902 .) The conduit  900  may be attached to the delivery device  902  using the natural resiliency of the conduit  900 . Or, in those cases where the conduit is spring loaded, the conduit  900  restrained in a reduced profile and may be removably affixed to the delivery device  902  using an adhesive, or a removable sleeve such as a heat shrink tube. In this example, the balloon catheter  902  has several balloons including a distal balloon  904 , a proximal balloon  906 , and a center balloon (not illustrated in  FIG. 12A ).  FIG. 12B  illustrates the inflation of the distal  904  and proximal  906  balloons to situate the extension members  908 . Accordingly, the extension members  908  for a flange or collet about the airway wall  114 . The balloons  904 ,  906  may be inflated simultaneously, or in a desired sequence. In any case, deployment of the balloons  904 ,  906  may serve to center the conduit  900  in the collateral channel.  
       FIG. 12C  illustrates inflation of the center balloon  912  which causes expansion of the center section  910  of the conduit  900 . If the conduit  900  is affixed to the delivery device  902 , expansion of the center balloon  912  causes release of the conduit  900  by release of the adhesive or breaking of the heat shrink tubing (not shown). In any case, the means of attachment may be bioabsorbable and remain in the body, or may remain affixed to the delivery device  902  and is removed with removal of the delivery device  902 .  FIG. 12D  illustrates the conduit  900  affixed to the airway wall  114  after the delivery device  902  is removed from the site. Another method of deploying a conduit includes restraining the conduit about a delivery device using a wire or string tied in a slip-knot or a series of slip-knots. When the conduit is delivered to a desired location, the proximal end of the wire or string may be pulled which releases the wire/string and deploys the conduit.  FIGS. 12E  and  12 F illustrate possible ways to manipulate a conduit  914  for placement in an airway wall  114  using a delivery device  916 .  FIG. 12E  illustrates deployment of a delivery device  916  to place a conduit  914  within an opening in an airway wall  114 . The conduit  914  may be placed over a balloon  918  (or other expandable section) of the delivery device  916 .  FIG. 12F  illustrates deployment of the balloon  918  to place and expand the conduit  914 . In the variation illustrated in  FIGS. 12E and 12F , a balloon  918  serves several functions. The balloon  918  first expands and starts bending the extension members  920 . The balloon  918  continues to center the conduit  914  on the tissue and simultaneously begins to expand the conduit  914  and secures the conduit to the tissue.  
       FIGS. 12G and 12H  illustrate additional variations of deployment devices. In these variations, the deployment devices  922 ,  926  contain hourglass-shaped balloons  924 ,  928 . The hour glass-shaped balloons  924 ,  928  contain an interior profile  923 . For deployment of a conduit (not shown) of the present invention, the conduit is placed on the balloon  924 ,  928 . As the balloon  924 ,  928  expands, the conduit expansion matches the interior profile  923  of the balloon  924 ,  928 . Accordingly, the hour glass-shaped balloon  924 ,  928  may be used to set the angle and orientation of the expandable members of a conduit as well as the expansion of a center section of the conduit.  
       FIG. 12I  illustrates another variation of an hour glass shaped balloon delivery device  930 . This variation of the hour glass shaped balloon  932  is designed to expand extension members (not shown) of a conduit (not shown) at a particular angle  934 . The orientation of the balloon  932  may be designed as needed to impart the desired angle to the extension members of the conduit. The balloons described herein may be constructed of polyethylene terephthalate (PET) or any other material which is used in the construction of balloon catheters.  
       FIG. 13A  illustrates a method of placing a conduit within lung tissue.  FIG. 13A  illustrates the advancement of an access device  940  into the airways  100  of a lung. The access device  940  will have at least one lumen or worlcing channel  942 . The access device  940  will locate an approximate site  944  for creation of a collateral chaimel. A bronchoscope or other similar type of endoscope may be used as the access device  940 . In cases where the access device  940  is a bronchoscope or similar device, the access device  940  is equipped so that the surgeon may observe the site for creation of the collateral channel. However, it is contemplated that the method of placing a conduit within lung tissue may be performed using non-invasive imaging techniques as well. In such a case, the access device  940  as well as the other devices discussed herein, may be configured for detection by the particular non-invasive imaging technique such as fluoroscopy, “real-time” computed tomography scanning, or other technique being used.  
       FIG. 13B  illustrates a blood vessel detection device  946  advanced through the channel  942  of the access device  940  towards the site  944 . The site  944  is then inspected to determine whether a blood vessel is adjacent to the site. As discussed herein, it may be desirable to avoid blood vessels when creating a collateral channel. Some possible examples of the detection device  946  are disclosed throughout this disclosure.  
       FIG. 13C  illustrates the creation of a collateral channel  112  by a hole-making device  948 . Examples of hole-making devices  948  are disclosed throughout this specification. Furthermore, variations of this invention include the use of devices which are equipped for detection and hole-making. Such devices are also disclosed throughout this specification. As shown in  FIG. 13C , the device  948  may be manipulated to a position that is optimal for creation of the collateral channel  112 . It is noted that the access device or the hole-making device may be steerable. Such a feature may assist in the positioning of any of the devices used in the inventive method. Although it is not illustrated, as discussed herein, it is desirable to create the collateral channel such that it is in fluid communication with an air-sac. The fluid communication allows for the release of trapped gasses from the hyper-inflated lung.  
       FIG. 13D  illustrates another variation of the inventive method in which a guide-member, such as a guide-wire  950 , or other similar device, is inserted into the collateral channel  112 . It is noted that the use of a guide-member  950  is optional.  
       FIG. 13E  illustrates the advancement of a catheter device  952  into the collateral channel. In the variations using a guide-member  950 , the catheter  952  is advanced over the guide-member  950  and into the collateral channel  112 . One variation of the inventive method includes the use of a catheter  952  which has a conduit  954  attached thereto. Some examples of the conduit  954  as well as catheter type delivery devices  952  are disclosed throughout this disclosure. If the conduit  954  is of the type that is not self-expanding, the catheter  952  may also be configured to expand the conduit  954  within the collateral channel  112 .  
       FIG. 13F  illustrates the conduit  954  placed within the collateral channel  112  and the withdrawal of the guide-member  950 , catheter  952 , and the access device  940 . As shown by the arrows of  FIG. 13F , the conduit  954  maintains the collateral channel  112  open so that trapped non-functional air is evacuated from the hyper-inflated lung.  
      It is noted that a variation of the inventive method includes using a guide-wire to create the collateral channel and leaving the guide-wire to extend through the collateral channel. Accordingly, a conduit may be advanced over the guide-wire into the collateral channel.  
      The invention further includes methods of evaluating individuals having a diseased lung to assess inclusion of the individual for the procedure.  
      The method comprises the steps of performing pulmonary function tests on the individual. The pulmonary function tests may obtain such values as FEV (forced expiratory volume), FVC (forced vital capacity), FEF 25%-75%  (forced expiratory flow rate), PEFR (peak expiratory flow rate), FRC (functional residual capacity), RV (residual volume), TLC (total lung capacity), and/or flow/volume loops.  
      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. FEF 25%-75%  measures the rate of air flow during a forced expiration divided by the time in seconds for the middle half of expired volume. PEFR measures the maximum flow rate during a forced exhale starting from full inspiration. FRC is the volume of air remaining in the lungs after a full expiration. RV is the FRC minus the expiratory reserve volume. TLC is the total volume in the lungs at the end of a full inspiration. Flow/volume loops are graphical presentations of the percent of total volume expired (on the independent axis) versus the flow rate during a forced expiratory maneuver.  
      The invention further comprises methods to determine the completion of the procedure. This variation of the invention comprises the step of performing pulmonary function tests as described above, creating collateral channels in the lungs, performing a post-procedure pulmonary function test, obtaining clinical information, comparing the results of the tests, evaluating the clinical information with the results of the test to determine the effectiveness of the procedure.  
      Another method to determine the completion of the procedure includes checking the resistance of airflow upstream from a location of a collateral channel. The method includes making a collateral channel, checking airflow, measuring resistance to airflow, and repeating the procedure until acceptable resistance is obtained. Because the collateral channel allows for the release of trapped air, the resistance to airflow should decrease. A body plethysmograph or other suitable equipment used to measure in pulmonary medicine may be used to determine the resistance to airflow.  
      A measurement of total lung volume may be used to determine when the lung is suitably deflated and therefore when enough collateral channels are created. Or, non-invasive imaging may be used to determine pre and post procedure lung volume or diaphragm position.  
      An evaluation of the effectiveness of the procedure may also include creating a collateral channel then sealing the channel with a balloon catheter. The distal end of catheter is then opened for a measurement of the flow of trapped air through the catheter.  
      This variation of the invention includes obtaining clinical information regarding the quality of life of the individual before and after any procedures, physical testing of the pulmonary system of the individual, and a general screening for pulmonary condition.  
      The invention farther includes a medical kit for improving gaseous flow within a diseased lung. The components of the kit may include a conduit, a hole-making device, and/or a detection device all of which are of the present invention and as described herein. The kit may further contain a power supply, such as an RF generator, or a Doppler controller which generates and analyzes the signals used in the detection devices. The kit may include these components either singly or in combination. The kit of the present invention may also contain instructions teaching the use of any device of the present invention, or teaching any of the methods of the present invention described herein. The instructions may actually be physically provided in the kit, or it may be on the covering, e.g., lidstock, of the kit. Furthennore, the kit may also comprise a bronchoscope, or guide-member (such as a guide-wire), or other such device facilitating performance of any of the inventive procedures described herein.  
      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.