Devices and methods for maintaining collateral channels in tissue

#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.

#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.

#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.

#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.