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.

Claims

1. A system for detecting collateral ventilation into a lung compartment in a patient, said system comprising: a catheter adapted to be introduced transtracheally to a bronchus leading to a target lung compartment; an occlusion member on a distal region of the catheter, said occlusion member being adapted to selectively occlude the bronchus; and an accumulator connectable to the catheter to accumulate air exhaled from the catheter over time.

2. A system as in claim 1, wherein the accumulator comprises a slack collection bag which has substantially no resistance to filling with air.

3. A system for evaluating a target lung compartment comprising: an instrument positionable within a lung passageway leading to the target lung compartment so that the target lung compartment is isolated, wherein the instrument includes a mechanism for injecting a compound to the target lung segment; and at least one sensor which generates measurement data reflecting pressure within the target lung segment.

4. A system as in claim 3, further comprising a processor which performs computations with the use of the measurement data reflecting pressure within the target lung segment.

5. The system as in claim 4, wherein the computations include calculating a degree of hyperinflation of the target lung compartment.

6. The system as in claim 4, wherein the computations include calculating a state of compliance of the target lung compartment.

7. The system as in claim 4, wherein the computation includes calculating collateral resistance of the target lung compartment.

8. The system as in claim 4, wherein the measurement data reflecting pressure comprises generating a plurality of measurement of pressure over predetermined time period.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a perspective view of an isolation and deflation catheter constructed in accordance with the principles of the present invention.

[0025] FIGS. 2-4 illustrate alternative placements of one-way flow elements within a central lumen of the catheter of FIG. 1.

[0026] FIG. 5 illustrates the trans-tracheal 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.

[0027] FIGS. 6A-6D illustrate use of the catheter as placed in FIG. 5 for isolating and reduction of the volume of the diseased lung region in accordance with the principles of the present invention.

[0028] FIG. 7 is a graph showing the relationship between collateral resistance R.sub.coll and residual volume reduction in an isolated lung compartment.

DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring to FIG. 1, 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, a proximal end 16, and an expandable occluding member 15, such as an inflatable balloon, mounted near the distal end 14. Catheter body 12 also includes at least one lumen or central passage 18 extending generally from the distal end 14 to the proximal end 16. Lumen 18 has a distal opening 19 at or near the distal end 14 in order to permit air or other lung gases to enter the lumen 18 and flow in a distal-to-proximal direction out through the proximal end of the lumen 18. Optionally, a hub 20 will be provided at the proximal end 16, but the hub 20 is not a necessary component of the catheter 10.

[0030] The catheter 10 is equipped to seal the area between the catheter body 12 and the bronchial wall such that only the lumen 18 is communicating with the airways distal to the seal. The seal, or isolation, is accomplished by the use of the occluding member 15, such as an inflatable member, attached to (or near) the distal tip 14 of the catheter 10. When there is an absence of collateral channels connecting the targeted isolated compartment to the rest of the lung, the isolated compartment will unsuccessfully attempt to draw air from the catheter lumen 18 during inspiration of normal respiration of the patient. Hence, during exhalation no air is returned to the catheter lumen. In the presence of collateral channels, an additional amount of air is available to the isolated compartment during the inspiratory phase of each breath, namely the air traveling from the neighboring compartment(s) through the collateral channels, which enables volumetric expansion of the isolated compartment during inspiration, resulting during expiration in air movement away from the isolated compartment to atmosphere through the catheter lumen and the collateral channels. If it is desired to perform Endobronchial Volume Reduction (EVR) on a lung compartment, the lung compartment may be analyzed for collateral ventilation prior to treatment to determine the likelihood of success of such treatment. Further, if undesired levels of collateral ventilation are measured, the collateral ventilation may be reduced to a desired level prior to treatment to ensure success of such treatment.

[0031] 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 FIG. 2, in one embodiment a one-way flow element 22 may be provided in the lumen 18 near the distal end 14 of the catheter body 12, immediately proximal of the distal opening 19. In an alternative embodiment, as in FIG. 3, the same one-way flow element 22 may be provided in the lumen 18 more proximally (either still near the distal end 14 or even more proximally in some embodiments). As shown in FIGS. 2 and 3, the one-way flow element 22 may be 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 valve 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 solid line.

[0032] 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. In some embodiments where the one-way flow element 22 (or elements) is located within the lumen 18 of the catheter body 12, the hub 20 may be removable, or alternatively the catheter 10 may not include a hub. As will be explained further below, this may facilitate leaving the catheter 10 in a patient for diagnostic and/or treatment purposes. For example, if the catheter 10 is advanced into a patient through a bronchoscope, the hub 20 may be detached to allow the bronchoscope to be removed proximally over the catheter 10, thus leaving the catheter body 12 with the one-way flow element 22 in the patient.

[0033] 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.

[0034] In some embodiments, the catheter 10 may be coupled with a one-way valve, a flow-measuring device or/and a pressure sensor, all of which are external to the body of the patient and are placed in series so as to communicate with the catheter's inside lumen 18. The one-way valve prevents air from entering the target lung compartment from atmosphere but allows free air movement from the target lung compartment to atmosphere. The flow measuring device, the pressure sensor device and the one-way valve can be placed anywhere along the length of the catheter lumen 18. The seal provided by the catheter 10 results, during expiration, in air movement away from the isolated lung compartment to atmosphere through the catheter lumen 18 and the collateral channels. Thus, air is expelled through the catheter lumen 18 during each exhalation and will register as positive airflow on the flow-measuring device. Depending on the system dynamics, some air may be expelled through the catheter lumen 18 during exhalation in the absence of collateral channels, however at a different rate, volume and trend than that in the presence of collateral channels.

[0035] 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. 5. 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 10 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. In some embodiments, the catheter may be introduced through a flexible bronchoscope (not shown in FIG. 5).

[0036] Referring now to FIGS. 6A-6D, 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, the expandable occluding element 15 is expanded to occlude the airway. The expandable occluding element may be a balloon, cuff, or a braided balloon as described in copending applications Ser. Nos. 60/823,734 (Attorney Docket No. 017534-003800US), filed on Aug. 28, 2006, and 60/828,496 (Attorney Docket No. 017534-003900US) 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. 6A, air from the diseased region DR flows outwardly through the lumen 18 and the one-way valve element 22, 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.

[0037] As shown in FIG. 6B, 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. 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 is increased relative to the pressure within the diseased region.

[0038] As shown in FIG. 6C, after some time, 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, treating the patient may comprise occluding the airway AW feeding the diseased region DR, by applying heat, radiofrequency energy, glues, or preferably by implanting an occluding element 30, as shown in FIG. 6D. Implantation of the occluding element 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. In some embodiments, before more permanently occluding the airway, treating the patient may comprise aspirating the target lung compartment. When accessing a lung compartment through an occlusal stent, volume reduction therapy may be performed by aspirating through the catheter and stent. The catheter is then removed and the volume reduction maintained.

[0039] As described in greater detail in U.S. patent application Ser. No. 11/296,951, from which the present application claims priority and which has been previously incorporated by reference, a catheter 10 as described herein may also be used to determine whether collateral ventilation is present in a lung. The 3 951 application describes a number of methods and devices for use in determining such collateral ventilation. Additionally or alternatively to those methods/devices, in one embodiment a catheter 10 (as described above) may be advanced through a bronchoscope and deployed as described in relation to FIGS. 5 and 6A-6D of the present application. In this embodiment, the catheter 10 includes at least one one-way flow element 22 within the lumen 18 of the catheter body 12. The hub 20 of the catheter 10 may then be detached, and the bronchoscope may be removed proximally over the catheter body 12, leaving the catheter body 12 in place in the patient. After a desired amount of time (anywhere from several minutes to twenty-four hours or more), an imaging study such as a CT scan may be taken of the patient's lung to see if the residual volume of the diseased lung compartment has decreased. Typically, this CT scan or other imaging study will be compared to a similar study taken before placement of the catheter 10 to determine if placement of the catheter has caused a reduction in residual volume in the lung compartment. If a reduction is noted, this may indicate that collateral ventilation is absent or minimal. This type of assessment may be used to help decide whether to treat a lung compartment further, such as with an implantable valve or blocking element.

[0040] In an alternative embodiment, the hub 20 of the catheter 10 may be left on, and the catheter 10 and bronchoscope may be left in the patient for a short time while an imaging study is performed.

[0041] 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.