US 20050049615 A1
The methods and devices disclosed altering gaseous flow within a lung to improve the expiration cycle of individuals having Chronic Obstructive Pulmonary Disease.
1. A method of improving gaseous flow within a diseased lung comprising the step of altering the gaseous flow paths within the lung.
2. The method of
selecting at least one site for collateral ventilation of the lung, and
creating at least one collateral channel in at least one of the sites.
3. The method of
6. The method of
7. The method of
8. The method of
(a) examining the lung using an imaging method selected from radiography, computer tomography, ultrasound, Doppler, MRI, PET and acoustic imaging to determine a location to alter the gaseous flow, and
(b) examining the lung using the non-invasive imaging method selected from radiography, computer tomography, ultrasound, doppler, MRI, PET and acoustic imaging to determine a number of collateral channels to be created.
9. The method of
10. The method of
11. The method of
14. The method of
(a) occluding a segment of the airway;
(b) adding or removing gas distally of the occluded segment; and
(c) monitoring flow or pressure distally of the occluded segment.
27. The method of
28. The method of
34. The method of
35. The method of
36. The method of
42. The method of
48. The method of
49. The method of
50. The method of
52. The method of
53. The method of
55. The method of
58. The method of
59. The method of
61. The method of
63. The method of claim 65 wherein said preserving step comprises cooling the tissue adjacent to the opening.
67. The method of
This application is a continuation of U.S. patent application Ser. No. 10/633,902, filed Aug. 4, 2003, which is a continuation of U.S. patent application Ser. No. 09/633,651 filed Aug. 7, 2000 now U.S. Pat. No. 6,692,494, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/147,528 filed Aug. 5, 1999 and 60/176,141 filed Jan. 14, 2000, all of which are incorporated in their entirety.
The invention relates to methods and devices to allow expired air able to pass 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 also directed to methods and devices to altering gaseous flow within a lung to improve the expiration cycle of an individual, particularly individuals having Chronic Obstructive Pulmonary Disease (COPD).
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' 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 to 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 occur 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 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 which allows expired 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.
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 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. The invention includes devices having at least one sensor for the above described imaging methods. In variations of the invention having multiple sensors, the sensors may be arranged in a linear pattern or in an array pattern. Also, the invention may have a mark to serve as a reference point while the device is remotely viewed.
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, 133Xe (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.
Another variation of the act of looking for blood vessels includes insertion of a probe into a wall of the natural airway for the detection of a blood vessel. Such a probe may, for example, detect the presence of a blood vessel upon encountering blood such as when the probe is inserted into a vessel. The probe may also use ultrasonic detection to determine the location of a vessel. For example, ultrasound may be used to determine changes in composition of the tissue beyond the airway wall for determination of the location of a vessel. A probe may, for example, use low frequency radio energy to induce heat at a point and determine the presence of a vessel by measuring a change in temperature due to the conduction of heat by the blood flowing within the vessel. Another variation is that the probe could detect changes in impedance given a pre-arranged discharge of current through the bloodstream. It is also contemplated that the probe is used, for example, purposely to find the blood vessel, so that an alternative site may be selected at a safe distance from the vessel.
Another variation of the invention is via the delamination of the blood vessel and the wall of an airway. This delamination may occur in many ways. For instance, the airway may be expanded until the vessel separates from the wall of the airway. Or, a vacuum may be applied within the interior of the airway using, for example, two occlusive balloons or the like to isolate a portion of the airway and apply a vacuum. The vacuum between the balloons constricts the diameter of the airway by collapsing the walls of the airway until the exterior walls separate from any blood vessel.
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 mm2 to 254 mm2. 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 at angled with respect to the axis of the airway.
Another variation of the invention involves creation of a collateral channel by creating an incision in a natural airway and using a blunt member to push the vessel away from the path of a collateral channel. Another variation of forming the collateral channel is, for example, by use of a mechanical process such as dilation, cutting, piercing, or bursting. For example, a balloon may be used to expand an incision made in the natural airway or the natural airway itself until a collateral channel is opened. Or, a mechanical cutter or piercing tool could be used to open and create the collateral channel. Another variation for creating a collateral channel includes making an incision in the natural airway and placing the wall of the airway in tension, then advancing a blunt instrument into the incision.
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 channel 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, 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.
A 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 inventive device may also comprise a hole-making assembly that is adapted to making collateral channels within tissue. The transducer assembly may include an acoustic lens which enables the transmission and detection of a signal over a tip of the device. 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.
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 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 device for altering gaseous flow in a diseased lung comprising a locator for locating a site for collateral ventilation of the lung, and optionally, a creating means for opening at least one collateral channel at the site. It is contemplated that the device includes a means for locating a blood vessel as described above. Also, as stated above, the device may use a mechanical, electrical, laser, ultrasonic, microwave, or chemical process for creating a collateral channel. Another variation of the device includes a means for coagulating blood upon the entry of the device into a blood vessel. Yet another variation of the device includes the means for locating and the means for creating are the same. The device may further include a means for simultaneously creating a plurality of collateral channels.
Another variation of the implant includes conduits constructed from materials that oppose the constriction of the natural airway over time during the expiration cycle of the lung. Yet another variation of the implant includes a device which expands as the pressure in the lung decreases during the expiration cycle.
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 teaching any of the methods described above.
The invention further includes the method of sterilizing any of the devices or kits described above.
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
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 expired 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.
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.
Of course, it is not the case that blood vessels are necessarily as conveniently located as is seen in
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. As mentioned above, non-invasive imaging may be used to locate blood vessels or to confirm the absence of a vessel at a site.
Another variation of the invention includes inserting a fluid into the airway to provide a medium for the sensor 228 couple to the wall of the airway 100 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 228 to the wall of the airway 100.
Another variation of the invention includes a means for marking the site. This variation of the device allows marking of 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 such imaging methods as radiography, computer tomography (CT) imaging, ultrasound imaging, doppler imaging, acoustical detection, or thermal detection or locating. Also, the mark may be detectable by direct visualization such as the case when a fiber optic cable is used.
Although not illustrated, the invention may 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 device of the present invention may also be configured to limit the depth of the collateral channel. In one example, 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.
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,
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 or chemicals.
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 from 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 the 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).
The transducer or transducers use 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 befurther 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
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.
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,
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 channel 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.
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.
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, eliptical, or any other multi-faceted or curved shape as required. The cross-sectional area of an implant 500 may be between 0.196 mm2 to 254 mm2.
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
Another variation of the conduit is illustrated in
Yet another variation of the conduit is found in
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.
In those cases where the conduit 812 of
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 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.
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.
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), FEF25%-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. FEF25%-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 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.