Methods and devices for passive residual lung volume reduction and functional lung volume expansion

Abstract

The volume of a hyperinflated lung compartment is reduced by sealing a distal end of the catheter in an airway feeding the lung compartment. Air passes out of the lung compartment through a passage in the catheter while the patient exhales. A one-way flow element associated with the catheter prevents air from re-entering the lung compartment as the patient inhales. Over time, the pressure of regions surrounding the lung compartment cause it to collapse as the volume of air diminishes. Residual volume reduction effectively results in functional lung volume expansion. Optionally, the lung compartment may be sealed in order to permanently prevent air from re-entering the lung compartment. The invention further discloses a catheter with a transparent occlusion element at its tip that enables examination of the lung passageway through a viewing scope.

Claims

1. A method of manufacturing a catheter for passive deflation of an isolated lung region without the need to implant a one-way valve structure in the lung, the method of manufacturing comprising: providing a catheter with a proximal end, a distal end and at least one lumen there between; providing a one-way flow element within the at least one lumen, the one-way flow element configured to inhibits flow through the lumen in a proximal-to-distal direction such that air cannot enter an isolated part of a lung during inhalation; providing an occluding member with a first end and a second end; attaching the first end of the occluding member to the inner surface of the lumen at the distal end of the catheter; and inverting the occluding member and attaching the second end of the occluding member to an outer portion of the catheter proximal to the distal end.

2. The method of claim 1, further comprising providing a hub coupled to the proximal end.

3. The method of claim 2, wherein the hub comprises a hub one-way flow element.

4. The method of claim 3, wherein the hub one-way flow element comprises a flap valve.

5. The method of claim 4, further comprising providing an inflation lumen extending along the catheter, wherein the expandable occluding element is inflatable.

6. The method of claim 5, further comprising providing an inflation port.

7. The method of claim 6, wherein the inflation port coupled to the inflation lumen and extends through the outer portion of the catheter proximal to the distal end.

8. The method of claim 7, wherein the expandable occluding member and a portion of the distal end of the catheter proximal between the first end and the second end of the expandable occluding member defines an inflatable volume.

9. The method of claim 8, wherein the inflation port fluidly couples the inflatable volume to the inflation lumen.

10. The method of claim 1, wherein at least a portion of the occluding member is transparent.

11. The method of claim 10, wherein the shape and material of the transparent occluding member are configured such that the transparent occluding member forms a wide angle lens.

12. The method of claim 1, wherein the occluding member is thermally bonded to the catheter.

13. The method of claim 1, wherein the first end of the occluding member is attached circumferentially to the inner surface of the lumen at the distal end of the catheter, and wherein the second end of the occluding member is attached circumferentially to the outer portion of the catheter proximal to the distal end.

14. The method of claim 1, wherein the one-way flow element comprises a duck-bill valve.

15. The method of claim 1, wherein providing the one-way flow element within the at least one lumen comprises providing a plurality of one-way flow elements within the at least one lumen.

16. The method of claim 1, wherein the one-way flow element comprises an actively controlled one-way flow control assembly.

17. The method of claim 1, wherein the one-way flow element comprises a passively controlled one-way flow control element.

18. The method of claim 1, wherein the expandable occluding element is transparent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a is a perspective view of an isolation and deflation catheter constructed in accordance with the principles of the present invention.

(2) FIG. 1b illustrates an embodiment of the occluding element covering the distal end of the catheter.

(3) FIGS. 1c and 1d show a method of manufacture of the embodiment of the occluding element shown in FIG. 1b.

(4) FIGS. 2-4 illustrate alternative placements of one-way flow elements within a central lumen of the catheter of FIG. 1.

(5) FIG. 5a shows an alternative embodiment of a one-way flow element comprising a valve controller coupled to sensors and an electrically-controlled valve.

(6) FIG. 5b shows an external console housing the one-way flow element shown in FIG. 5a.

(7) FIG. 6a shows a flowchart and FIG. 6b show flow and pressure graphs, illustrating the operation of the one-way flow element shown in FIG. 5a.

(8) FIG. 7 illustrates the trans-esophageal endobronchial placement of the catheter of FIG. 1 in an airway leading to a diseased lung region in accordance with the principles of the present invention.

(9) FIGS. 8a-8d illustrate use of the catheter as placed in FIG. 7 for isolating and reduction of the volume of the diseased lung region in accordance with the principles of the present invention.

(10) FIG. 9 is a graph showing the relationship between collateral resistance Rcoll and residual volume reduction in an isolated lung compartment.

DETAILED DESCRIPTION OF THE INVENTION

(11) Referring to FIGS. 1a and 1b, an endobronchial lung volume reduction catheter 10 constructed in accordance with the principles of the present invention includes an elongate catheter body 12 having a distal end 14 and a proximal end 16. Catheter body 12 includes at least one lumen 18 or central passage extending generally from the distal end 14 to the proximal end 16. Lumen 18 will have a distal opening 19 at or near the distal end 14 in order to permit air or other lung gases to enter the lumen and flow in a distal-to-proximal direction out through the proximal end of the lumen. Additionally, catheter body 12 will have an expandable occluding element 15 at or near the distal end 14, to occlude an air passageway during treatment.

(12) As mentioned above, in one embodiment the expandable occluding element 15 is disposed near the distal end of the catheter body to seal the passageway, while in an alternate embodiment the expandable occluding element 15 forms a cover of the rim of the catheter lumen in order to seal the passageway, prevent or inhibit mucus entry into the lumen, and shield the passageway wall from the tip of the catheter. In the alternate embodiment, the expandable occluding element 15 may be transparent to allow viewing of the passageway. These embodiments will now be described in more detail with reference to the Figures.

(13) In one embodiment of the catheter, as shown in FIG. 1a, the expandable occluding element 15 is located at or near the distal end 14. In this embodiment, the expandable occluding element 15 is configured such that the proximal and distal ends of the expandable occluding element 15 are attached to the outer surface of the catheter body 12. An inflation lumen 17A extends from the inflation port 17B to the expandable occluding element 15 to provide for expansion of the expandable occluding element 15.

(14) In an alternate embodiment, as shown in FIG. 1b, the expandable occluding element 15 is disposed at the distal end of the catheter body 12, and is configured to form a cover over the rim of the distal opening 19 of the catheter body 12. In this embodiment, the proximal end of the expandable occluding element 15 is attached to the outer surface of the catheter body 12, while the inner surface of the expandable occluding element 15 wraps over the rim of the catheter body 12 and is attached to the inner surface of the catheter body 12. Inflation lumen 17A is used to inflate the expandable occluding element 15 through inflation port 17B. When inflated, the expandable occluding element 15 will form a cover (or lip), over the rim of the catheter body 12, thereby preventing or inhibiting entry of mucus into the lumen 18 of the catheter, and preventing or inhibiting the opening 19 from contacting the walls of the passageway. The inflated expandable occluding element 15 also helps prevent or inhibit accidental placement of the catheter tip into an airway segment that is smaller than the intended airway segment. Additionally or optionally, the expandable occluding element 15 and the distal portion of the catheter body 12 comprise a transparent material to enable viewing past the expandable occluding element 15.

(15) Manufacture of the second embodiment of the catheter 10 is shown in FIGS. 1c and 1d. As shown in FIG. 1c, one end 15A of the expandable occluding element 15 is circumferentially attached to the inner wall of the lumen, using any suitable technique such as thermal bonding or adhesive bonding. Then, the expandable occluding element 15 is inverted over the catheter tip and catheter body 12, as shown in FIG. 1d. The second end 15B of the expandable occluding element 15, which is now proximal to the tip of the catheter, is attached circumferentially to the outer surface of the catheter body 12, using any suitable technique such as thermal bonding or adhesive bonding. The expandable occluding element 15 thus encloses the outer rim of the distal end of the catheter. Further, the expandable occluding element 15 is configured such that it is fed for inflation by an inflation port 17B leading from an inflation lumen 17A. Though the figures describe a preformed balloon-like expandable occluding element 15, any suitable material of any shape may be used to manufacture the expandable occluding element 15 in the described manner, as should be obvious to one of ordinary skill in the art. For example, as described above, some portion of the catheter body 12 and/or of the expandable occluding element 15 may be configured to be transparent. Optionally, a hub 20 will be provided at the proximal end, for example as shown in FIG. 1a, but the hub is not a necessary component of the catheter.

(16) Additionally and optionally, catheter 10 is configured to be introducible into the passageway via a viewing scope such as a bronchoscope (not shown). Use of the scope, in conjunction with a catheter 10 comprising one or more transparent components as described above, enables enhanced viewing of the body passageway during diagnostic or treatment procedures, by allowing a user to view the body passageway through the transparent expandable occluding element 15. Additionally, a transparent expandable occluding element 15 could serve as a lens to be used in conjunction with the scope. When so used, light from the scope would interact with the occluding element 15 in such a manner as to enable more enhanced viewing than would be obtained without the use of a transparent occluding element 15. Examples of such enhanced viewing could include: obtaining wide angle or fish-eye views or a greater field of vision, telephoto properties (macro, zoom, etc.) or color filtration. These can be achieved by manipulating the material properties of the expandable occluding element 15.

(17) The technique of using a transparent, expandable element on a catheter may also be used independently. For example, in one embodiment, a catheter may be equipped with a transparent expandable occluding element 15 similar to that shown in FIG. 1b. In such an embodiment, the transparent expandable occluding element 15 serves as an image enhancer or diagnostic lens, and need not be fully occlusive. Similar to the above description, when used in conjunction with a viewing scope, it would enable more enhanced diagnostic viewing than would be obtained without the use of a transparent expandable occluding element 15. Examples of such enhanced viewing could include: obtaining wide angle or fish-eye views or a greater field of vision, telephoto properties (macro, zoom, etc.) or color filtration. These can be achieved by manipulating the material properties of the transparent expandable occluding element 15. Additionally, the transparent expandable occluding element 15 may be configured to allow for therapeutic procedures, such as delivery of a therapeutic electromagnetic energy (e.g., laser, infrared, etc.) to the lung or other tissue. In such a case, the surface, shape, material, size or other properties of the lens can be chosen to allow a user to manipulate the therapeutic laser energy. For example a user could focus or diffuse the energy by moving the source of laser energy back and forth relative to the transparent expandable occluding element 15.

(18) The present invention relies on placement of a one-way flow element within or in-line with the lumen 18 so that flow from an isolated lung compartment or segment (as described hereinbelow) may occur in a distal-to-proximal direction but flow back into the lung compartment or segment is inhibited or blocked in the proximal-to-distal direction. As shown in FIGS. 2-4, a one-way flow element 22 may be provided in the lumen 18 near the distal end 14 of the catheter body 12, optionally being immediately proximal of the distal opening 19. As shown, the one-way flow element 22 is a duck-bill valve which opens as shown in broken line as the patient exhales to increase the pressure on the upstream or distal side of the one-way flow element 22. As the patient inhales, the pressure on the upstream or distal side of the valve is reduced, drawing the valve leaflets closed as shown in full line.

(19) Alternatively or additionally, the one-way flow element 22 could be provided anywhere else in the lumen 18, and two, three, four, or more such valve structures could be included in order to provide redundancy.

(20) As a third option, a one-way valve structure 26 in the form of a flap valve could be provided within the hub 20. The hub 20 could be removable or permanently fixed to the catheter body 12. Other structures for providing in-line flow control could also be utilized, as will be presently described.

(21) In addition to the passive one-way valve structures described above, one-way flow functionality may be provided using an actively controlled one-way flow control assembly. One-way flow can be controlled by measuring the flow and pressure through the lumen and using this information to determine the beginning and end of inhalation and exhalation cycles and thereby determining whether the valve should remain open or closed. In one embodiment, the one-way flow control assembly is provided as part of an external console attached in-line with the catheter lumen. The console comprises a channel for air flow to which the proximal end of the catheter connects via a standard connector. When the patient exhales, air is forced through the catheter lumen into the console's air channel, and then exits through an exhaust port of the console. The one-way flow control assembly comprises a valve that is within or in-line with the catheter lumen and can be opened or closed by a valve controller to control the air flow through the air channel. The valve controller opens and closes the valve based on input from flow and pressure sensors within or in-line with the catheter lumen. The sensors measure the air flow and air pressure to detect the inhalation and exhalation cycles of the patient. Based on input from the sensors, the valve controller opens the valve at the beginning of the exhalation cycle, and closes the valve at the beginning of the inhalation cycle. The valve controller may control the valve electrically, magnetically, mechanically or through other means known in the art.

(22) FIG. 5a shows an illustration of such an actively controlled one-way flow control assembly provided as part of an external console. The external console 60 comprises an air channel 61, a connector 62, and an exhaust port 64. Catheter 10 is detachably coupled to air channel 61 using a standard connector 62, such that air channel 61 is in-line with lumen 18. Preferably, a filter 63 is provided between the air channel 61 and lumen 18 to maintain sterility of air channel 61 and promote reusability of console 60. Additionally, air flowing into air channel 61 is expelled through exhaust port 64. Console 60 comprises a one-way flow assembly 70 in-line with lumen 18 of catheter 10.

(23) One-way flow assembly 70 comprises an electrically controlled valve 71, a flow sensor 73, a pressure sensor 74, and a valve controller 75. In one embodiment, valve 71, flow sensor 73, and pressure sensor 74 are disposed within air channel 61. Valve controller 75 provides one-way flow functionality by opening and closing valve 71 based on flow and pressure signals received from sensors 73 and 74, respectively. When valve 71 is closed, it prevents air from flowing into the lumen of catheter 10 (during inhalation); during exhalation, valve 71 remains open and allows air to flow out of the isolated lung compartment.

(24) In one embodiment, valve 71 is a solenoid-based valve. Alternatively, valve 71 may be any other valve that can be opened and closed via an electrical control signal. Flow sensor 73 and pressure sensor 74, respectively, measure air flow and pressure in lumen 18. Valve controller 75 receives a flow indicator signal 76 from the flow sensor 73 and a pressure indicator signal 77 from pressure sensor 74 and produces a valve control signal 78 to open or close valve 71. Alternatively, one or more of flow sensor 73, pressure sensor 74, and valve 71 may reside within lumen 18 and be in communication with valve controller 75 via connections between the catheter 10 and console 60.

(25) FIG. 5b shows one embodiment of an external console 60 connected to catheter 10. External console 60 optionally comprises a visual display 79 that receives and displays flow and pressure data as sensed by sensors 73 and 74, for example, via a connection 72 to the controller 75. Optionally, visual display 79 is a touch-screen display allowing a user to interact with console 60.

(26) FIGS. 6a and 6b illustrate the operation of one-way flow assembly 70. FIG. 6a is a flowchart showing the operational steps of valve controller 75 as it produces the electrical valve control signal 78 to open or close valve 71 based on input from flow sensor 73 and pressure sensor 74. FIG. 6b is a graph showing exemplary signals generated by the flow sensor 73 (top panel) and pressure sensor 74 (bottom panel) during a series of respiration cycles. The flow and pressure direction during exhalation is herein referred to as the positive flow and pressure direction and plotted on the positive ordinate of the graphs in FIG. 6B, and the flow and pressure direction during inhalation is referred to as the negative flow direction and plotted on the negative ordinate of FIG. 6B.

(27) Initially, the patient may breathe normally through lumen 18 of catheter 10. Once the treatment is initiated (step 80)which could be accomplished using the visual display 79valve controller 75 waits for the completion of an inhalation cycle, until flow sensor 73 indicates a flow value that is greater than a specified flow threshold value. This is shown as step 81 in FIG. 6a and shown as the first flow and pressure cycle in FIG. 6B lasting for a period indicated as 81p. The flow threshold value is chosen to indicate the beginning of an exhalation cycle. FIGS. 6a and 6b and the present description assume an exemplary flow threshold value of zero. Optionally, the flow threshold value is configurable to a value other than zero.

(28) In step 82 in FIG. 6a (also indicating the positive flow and pressure in FIG. 6b), valve controller 75 maintains valve 71 in an open state during exhalation until flow sensor 73 receives a flow value less than or equal to zero. Thus, as is illustrated in FIG. 6b, step 82 lasts for a period indicated as 82p as long as flow sensor 73 senses an air flow value greater than zero.

(29) When flow sensor 73 senses a flow value that is less than or equal to zero, valve controller 75 closes valve 71 in step 83 in FIG. 6a and no air flows through the lumen into the lung compartment. As is shown in FIG. 6b, Step 83 occurs contemporaneously with the flow value reaching zero or lower at the point in time denoted 83p. Typically, the flow reduces to zero at the end of exhalation, at which point valve controller 75 closes the valve 71.

(30) The following steps of valve controller 75 refer to a pressure threshold value. The pressure threshold value is chosen to indicate the beginning of an exhalation cycle. This value is configurable, and in what follows, an example pressure threshold value of zero is assumed.

(31) Ideally, it is desirable that valve controller 75 reopen valve 71 when the pressure increases to or above the pressure threshold value. Realistically, given hardware imperfections, the pressure as sensed and reported by pressure sensor 74 at the end of exhalation may fluctuate around zero, causing chatter of valve 71. To prevent valve chatter, in step 84, valve controller 75 maintains valve 71 in a closed state while the pressure remains above a specified minimum pressure value, denoted as min_pressure in FIGS. 6a and 6b. This minimum pressuremin_pressureis configurable and set to a value appreciably less than the specified pressure threshold value. Thus, as is further shown in FIG. 6b, valve 71 remains closed during the period 84p.

(32) Optionally, during step 84, valve controller 75 also monitors pressure to ensure that valve 71 will open if the patient starts exhalation prior to the pressure decreasing to below min_pressure, To this end, during step 84, valve controller 75 is optionally configured to open valve 71 if pressure increases to a value that is above the pressure threshold value by an amount referred to as a safeguard offset value. The safeguard offset value is configurable.

(33) During step 85 in FIG. 6a, once the pressure passes below min_pressure, valve controller 75 maintains valve 71 in a closed state until the pressure increases to or passes the pressure threshold value. Referring to FIG. 6b, step 85 lasts the duration between the achievement of min_pressure in step 84 and the attainment of the pressure threshold value, with the period denoted as 85p in FIG. 6b.

(34) When the pressure increases to or passes the pressure threshold value, the valve controller 75 opens the valve 71 at step 86 in FIG. 6a. Thus, referring to FIG. 6b, the opening of the valve in step 86 occurs at point 86p and is contemporaneous with the pressure increasing to or passing a zero value. This allows air to empty from the lung compartment in communication with lumen 18.

(35) Thereafter, as the patient resumes inhalation, the valve controller 75 resumes operation at Step 82 (close valve 71 and prevent airflow into the target lung compartment), for a new respiration cycle, until the lung reduction process is terminated.

(36) Use of the endobronchial lung volume reduction catheter 10 to reduce the residual volume of a diseased region DR of a lung L is illustrated beginning in FIG. 7. Catheter 10 is introduced through the patient's mouth, down past the trachea T and into a lung L. The distal end 14 of the catheter 10 is advanced to the main airway AW leading into the diseased region DR of the lung. Introduction and guidance of the catheter may be achieved in conventional manners, such as described in commonly-owned U.S. Pat. Nos. 6,287,290; 6,398,775; and 6,527,761, the full disclosures of which are incorporated herein by reference.

(37) Referring now to FIGS. 8A-D, functioning of the one-way valve element in achieving the desired lung volume reduction will be described. After the distal end 14 of the catheter 10 is advanced to the feeding airway AW, an expandable occluding element 15 is expanded to occlude the airway. The expandable occluding element 15 may be a balloon, cuff, or a braided balloon as described in application 60/823,734, filed on Aug. 28, 2006, and 60/828,496 filed on Oct. 6, 2006, the full disclosures of which are incorporated herein by reference. At that point, the only path between the atmosphere and the diseased region DR of the lung is through the lumen 18 of the catheter 10. As the patient exhales, as shown in FIG. 8A, air from the diseased region DR flows outwardly through the lumen 18 and the one-way flow element 22, one-way flow assembly 70, or any other one-way flow structure, causing a reduction in residual air within the region and a consequent reduction in volume. Air from the remainder of the lung also passes outward in the annular region around the catheter 10 in a normal manner.

(38) As shown in FIG. 8B, in contrast, when the patient inhales, no air enters the diseased regions DR of the lung L (as long as there are no significant collateral passageways), while the remainder of the lung is ventilated through the region around the catheter. It will be appreciated that as the patient continues to inhale and exhale, the air in the diseased region DR is incrementally exhausted, further reducing the lung volume as the external pressure from the surrounding regions of the lung are increased relative to the pressure within the diseased region. As shown in FIG. 8C, after sometime, typically seconds to minutes, air flow from the isolated lung segment will stop and a maximum or near-maximum level of residual lung volume reduction within the diseased region DR will have been achieved. At that time, the airway AW feeding the diseased region DR can be occluded, by applying heat, radiofrequency energy, glues, or preferably by implanting an occluding device 30, as shown in FIG. 8D. Implantation of the occluding device may be achieved by any of the techniques described in commonly-owned U.S. Pat. Nos. 6,287,290; and 6,527,761, the full disclosures of which have been previously incorporated herein by reference.

(39) While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.