Patent Application
20130102999
Embodiments of the present invention relate to the field of removing peritoneal ascites, pleural effusion fluids, and the like. More particularly, embodiments of the present invention relate to a catheter device that can perform a drainage function and a sclerosis-inducting function while protecting tissue from direct exposure to concentrated sclerotic agents.
Ascites describes an accumulation of fluid in the peritoneal cavity. Pleural effusion refers to the effusion of fluid into the pleural space. Both excess fluid accumulation conditions may be treated with a drainage apparatus of the type shown in
The pleural space normally contains approximately 5 to 20 ml of fluid. The pH, glucose and electrolytes of the fluid are equilibrated with plasma, but the fluid is relatively protein-free. The fluid is the result of the hydrostatic-oncotic pressure of the capillaries of the parietal pleura. About 80-90% of the fluid is reabsorbed by the pulmonary venous capillaries of the visceral pleura, and the remaining 10-20% is reabsorbed by the pleural lymphatic system. The turnover of fluid in the pleural space is normally quite rapid-roughly 35 to 75% per hour, so that 5 to 10 liters of fluid move through the pleural space each day.
A disruption in the balance between the movement of fluid into the pleural space and the movement of fluid out of the pleural space may produce excessive fluid accumulation in the pleural space. Such disruptions may include, for example, (1) increased capillary permeability resulting from inflammatory processes such as pneumonia, (2) increased hydrostatic pressure as in congestive heart failure, (3) increased negative intrapleural pressure as seen in atelectasis (partial or total lung collapse), (4) decreased oncotic pressure as occurs in the nephrotic syndrome with hypoalbuminemia, and (5) increased oncotic pressure of pleural fluid as occurs in the inflammation of pleural tumor growth or infection. Pleural effusion is particularly common in patients with disseminated breast cancer, lung cancer or lymphatic cancer and patients with congestive heart failure, but also occurs in patients with nearly all other forms of malignancy.
The clinical manifestations of pleural effusion include dyspnea, cough and chest pain which diminish the patient's quality of life. Although pleural effusion typically occurs toward the end of terminal malignancies such as breast cancer, it occurs earlier in other diseases. Therefore relieving the clinical manifestations of pleural effusion is of a real and extended advantage to the patient. For example, non-breast cancer patients with pleural effusion have been known to survive for years.
There are a number of treatments for pleural effusion. If the patient is asymptomatic and the effusion is known to be malignant or paramalignant, treatment may not be required. Such patients may develop progressive pleural effusions that eventually do produce symptoms requiring treatment, but some will reach a stage where the effusions and reabsorption reach an equilibrium that is still asymptomatic and does not necessitate treatment.
Pleurectomy and pleural abrasion is generally effective in obliterating the pleural space and, thus, controlling the malignant pleural effusion. This procedure is done in many patients who undergo thoracotomy for an undiagnosed pleural effusion and are found to have malignancy, since this would prevent the subsequent development of a symptomatic pleural effusion. However, pleurectomy is a major surgical procedure associated with substantial morbidity and some mortality. Therefore, this procedure is usually reserved for patients with an expected survival of at least several months, who are in relative good condition, who have a trapped lung, or who have failed a sclerosing agent procedure.
In general, systemic chemotherapy is disappointing for the control of malignant pleural effusions. However, patients with lymphoma, breast cancer, or small cell carcinoma of the lung may obtain an excellent response to chemotherapy. Another approach to removing fluid from the pleural space has been to surgically implant a chest tube. Such tubes are commonly quite rigid and fairly large in diameter and are implanted by making a surgical incision and spreading apart adjacent ribs to fit the tube into place. Such procedures are painful to the patient, both initially when the chest tube is inserted and during the time it remains within the pleural space.
Thoracentesis is a common approach to removing pleural fluid, in which a needled catheter is introduced into the pleural space through an incision in the chest cavity and fluid is positively drawn out through the catheter using a syringe or a vacuum source. The procedure may also include aspiration utilizing a separate syringe. There are a number of difficulties in thoracentesis, including the risk of puncturing a lung with the catheter tip or with the needle used to introduce the catheter, the risk of collapsing a lung by relieving the negative pressure in the pleural space, the possibility of aggravating the pleural effusion by stimulating fluid production in the introduction of the catheter, and the risk of infection. One of the primary difficulties with ordinary thoracentesis procedures is that fluid reaccumulates in the pleural space relatively quickly after the procedure is performed, and so it is necessary to perform the procedure repeatedly—as often as every few days.
Modern pleural and peritoneal drainage systems have made it possible for patients to use devices like those illustrated in
Chemical pleurodesis may use irritants and/or antibiotic materials (also known as sclerotic agents or accelerodesis agents) that may also provide mechanical irritation to trigger cell growth and/or resist infection. Examples of materials known and used include bleomycin, tetracycline, and povidone iodine. As another example, a slurry of talc can be introduced into the pleural space. These materials generally are introduced through a thoracic drainage catheter. The instilled chemicals cause irritation between the parietal and the visceral layers of the pleura which closes off the space between them and prevents further fluid from accumulating. Chemical pleurodesis may be a painful procedure, so patients are often premedicated with a sedative and analgesics. A local anesthetic may be instilled into the pleural space, or an epidural catheter may be placed for anesthesia. Generally, to be effective, introduction of structures and materials for pleurodesis desirable will create irritation and then keep the space dry. In order to establish pleurodesis, it is preferable that the parietal and visceral layers of the pleura remain in juxtaposition. As such, it is preferable that when mechanical and/or chemical irritation is complete a drainage tube will remain in place to remove the fluid over the time it takes for the adhesion accomplishing pleurodesis to occur.
During chemical pleurodesis using a catheter surface-coated with (or otherwise eluting) a pleurodesis-inducing sclerotic agent, it may be preferable to minimize or prevent direct and/or concentrated contact of the agent with patient tissue. Accordingly, it would be advantageous to provide a catheter surface-coated with (or otherwise eluting) a pleurodesis-inducing sclerotic agent that is configured to minimize or prevent direct and/or concentrated contact of the agent with patient tissue.
In one aspect, embodiments may include embodiments of catheter devices configured to develop a sclerotic agent from a coated surface while minimizing direct tissue contact with a sclerotic agent coating. Different embodiments may include one or more of mechanical barriers or other structures configured to impede tissue from direct contact with a catheter surface, reliance upon fluid diffusion from a protected sclerotic agent coating, and/or other structures or instrumentalities.
Embodiments generally are described with reference to the drawings in which like elements are generally referred to by like numerals. The relationship and functioning of the various elements of the embodiments may better be understood by reference to the following detailed description. However, embodiments are not limited to those illustrated in the drawings. It should be understood that the drawings are not necessarily to scale, and in certain instances details may have been omitted that are not necessary for an understanding of embodiments of the present invention, such as—for example—conventional fabrication and assembly.
The present invention now will be described more fully hereinafter. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As used in this specification and the claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise. Throughout the specification, the terms “distal” and “distally” shall denote a position, direction, or orientation that is generally away from the physician and/or toward the patient. Accordingly, the terms “proximal” and “proximally” shall denote a position, direction, or orientation that is generally towards the physician and/or away from the patient.
Within a device for accelerating and/or enhancing pleurodesis, it may be desirable to provide a distal indwelling portion of the tube that is coated at least partially with a substance that is intended to be delivered to the body over an extended period of time in a diluted, consistent, and/or titrated manner. One example of such a system maybe a tube body configured for pleurodesis of the pleural space by means of a sclerosing agent such as, for example, silver nitrate. In these instances, it is preferable that the silver nitrate coating in its base/concentrated form not contact the surrounding tissue directly due to its high concentration and potential tissue reactions thereto. The coating most preferably will be eluted or otherwise be released over time from the catheter. Other suitable sclerotic agents may include antimicrobial agents, or other materials configured for inducing pleurodesis (e.g., polyvinylpyrrolidone (PVP), talc (e.g., as a slurry), bleomycin, mitoxantrone, mitomycin, thiotpea, cytarabine, quinacrine, tetracycline (defined herein to include tetracycline derivative such as doxycycline and minocycline), OK432 (Streptococcus pyogenes type A3), SSAg (Staphylococcus aureus superantigen), fibrin glue, povidone iodine (PVP-I), autologous “blood patch,” or any combination thereof).
As described above, pleurodesis may be induced or enhanced by providing a sclerotic agent. One means for this is as a coating on at least one internal and/or external surface to the distal catheter length 212 configured to indwell the patient. However, it may be preferable that such a coating not directly contact patient tissue, as the concentration of a sclerotic agent coating may have an excessively irritating or other adverse effect. Instead, it is preferable that the sclerotic agent of the coating be allowed to diffuse through the pleural or other space and thereby to contact the patient tissue in a less concentrated manner. One means for providing this is described with reference to
The regions to be masked and thereby left uncoated are most preferably selected and configured to be regions of the distal length most likely to directly contact patient tissue when installed into a body space. For different body spaces, patient anatomy, and/or device sizes, the masked regions may be custom-designed, or may be configured generally for a desired application. A distal terminus region or any other region or plurality of regions of the eluting may be masked and thereby remain uncoated with sclerotic agent. Regions that are most desired to be masked and remain uncoated may be identified by a treating physician, by observation of tube position in a patient with a prior uncoated tube, or by other means.
In this or other embodiments, one or more surfaces of the tube lumen 217 may be provided with a coating or otherwise elutable application of a sclerotic agent. This location will prevent or decrease the likelihood of direct and/or concentrated contact between the sclerotic agent and patient tissue when the device is disposed indwelling a patient. The sclerotic agent eluent can travel through the drainage apertures 218 and/or a distal end opening to promote pleurodesis.
This weighted embodiment most preferably is configured such that the weight 344 will generally orient a coated eluting portion 333, which is coated with a sclerotic agent, away from direct contact with patient tissue when the distal catheter length 312 is installed in a patient. For example, when the distal catheter length 312 is installed as indwelling in a lateral or dorsal pleural space of a patient, the eluting portion 333 (embodied as a coated distal region) will generally be held away from direct contact with patient tissue so that the sclerotic agent contacts that tissue to promote pleurodesis only in an at least somewhat diluted, diffused form rather than permitting direct contact with the surface coating of the eluting portion 333. Even if some direct contact is permitted, it is strongly preferred that the surface coating of the eluting portion 333 not directly contact major blood vessels of the mediastinum. Those of skill will appreciate in view of the present disclosure that appropriate placement of this embodiment with its weighted distal end will facilitate this orientation configured to minimize likelihood of direct contact.
In this embodiment, the relatively raised and depressed surfaces are formed as channels 443 and dividers 441.
The tube 667 may be configured as mesh, woven, braided, or the like (including attached but non-interlaced structures) and is porous such that it is permeable to the sclerotic agent of the eluting surface 633 while forming a spacing barrier configured to prevent direct contact of adjacent tissue with the sclerotic agent of the eluting surface 633. Those of skill in the art will appreciate that various metallic, polymeric, and other materials well-known in the art may be used to construct such a tube (which may be constructed similarly to any number of stent configurations known in the art). As with the other embodiments described herein, the spacer tube 667 preferably will prevent direct and/or otherwise concentrated contact of sclerotic agent coating with tissue around the eluting portion 633 when the device is indwelling a patient. However, the tube 667 will permit a low concentration of the sclerotic agent to pass therethrough to promote pleurodesis. The spacer tube 667 may be attached along the eluting surface 633 and/or may be spaced apart from it by being constructed with an inner diameter that is larger than the outer diameter of the eluting portion 633.
The at least two relatively raised external surfaces 771 are disposed at least generally circumferentially around the outer surface of the distal catheter length 712. The at least two relatively raised external surfaces 771 may be parallel (as shown in
It should be appreciated that these configurations will decrease the likelihood of direct contact between adjacent tissue and the sclerotic agent when the distal catheter length 712 is disposed as indwelling in a patient's body space. In each of these embodiments, when the distal catheter length 712 is disposed as indwelling in a patient's body space, it will generally be preferred to provide a concentration of the sclerotic agent in a suprasurface region immediately adjacent the at least one relatively depressed surface is greater than a concentration of the sclerotic agent in a suprasurface region immediately adjacent the at least one relatively raised surface. That is, to the extent that a suprasurface region immediately above the catheter length's surface is capable of carrying sclerotic agent eluted from the device, the concentration immediately adjacent/above the relatively depressed region(s) will be greater than the concentrations immediately adjacent/above the relatively raised region(s).
The spacing between the at least two relatively raised external surfaces 771 preferably is configured relative to the height of each of the at least two relatively raised external surfaces 771 such that tissue (e.g., pleural tissue) likely to be adjacent to the distal catheter length 712 will generally be prevented from, or will at least have a reduced likelihood of, direct contact with the eluting surface 773 between the at least two relatively raised external surfaces 771. In certain embodiments, the at least two raised external surfaces 771 may be configured with a height that is will minimize direct contact between the eluting surface 773 and adjacent tissue. In some embodiments, the sclerotic agent may be distributed in a gradient fashion, with a higher concentration at or near the base of a raised surface 771 (where it may be more shielded from direct tissue contact) and lessening concentration further away from the raised surface 771.
Those of skill in the art will appreciate that embodiments not expressly illustrated herein may be practiced within the scope of the present invention, including that features described herein for different embodiments may be combined with each other and/or with currently-known or future-developed technologies while remaining within the scope of the claims presented here. For example, the various physical structures disclosed may also provide mechanical irritation promoting a desired sclerotic effect, and the structures and components disclosed herein may be combined with each other or other features. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting. And, it should be understood that the following claims, including all equivalents, are intended to define the spirit and scope of this invention. Furthermore, the advantages described above are not necessarily the only advantages of the invention, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment of the invention.
