Patent Application
20120265055
1. Technical Field
The present invention relates to tubular medical devices. More particularly, the invention relates to a tubular feeding device having a shapeable distal end for enhanced visualization under medical imaging.
2. Background Information
Patients for whom normal ingestion of food becomes difficult or impossible may require placement of a feeding tube to assist in providing their nutritional needs. For some individuals, such as comatose patients, stroke victims, or those with a compromised gastrointestinal (GI) tract, this may require placement of a tube that is introduced percutaneously into the stomach for delivery of nutritional products directly into the stomach. Such tubes for delivery of nutritional products into the stomach are generally referred to as gastrostomy tubes, or “G”-tubes.
In some situations, feeding a patient through a G-tube positioned in the stomach can be problematic. For example, the presence of certain congenital abnormalities in the patient's stomach may obstruct proper placement of the tube. Suitable placement may also be hindered when the patient exhibits severe gastric reflux and/or a high rate of aspiration. In these and other situations, nutritional targets may not be attained at a satisfactory rate through G-tube feeding. In such patients, feeding may often be accomplished at a suitable rate by inserting a feeding tube, sometimes referred to as a jejunal tube, or a “J”-tube, directly into the jejunum of the patient. The J-tube bypasses the stomach, thereby avoiding many congenital abnormalities, and decreasing the risk of gastric reflux and/or aspiration. The J-tube often provides better success in delivering nutrients than a G-tube, and allows the nutrients to be delivered and absorbed more rapidly.
Notwithstanding the foregoing, however, there are some difficulties associated with the use of jejunal feeding tubes. For example, due to the generally offset position of the jejunum relative to the stomach, it is often difficult to properly direct the distal end of a J-tube into the jejunum. J-tubes are typically very flexible, which contributes to the difficulty in directing the tubes to the desired area. In addition, once positioned, J-tubes are subject to dislodgement.
In view of the difficulties encountered in placing such tubes in the jejunum, radiographic imaging techniques, e.g., x-ray, are utilized to verify proper placement of such tubes. As health care workers must transport that patient to the radiology facility to obtain the x-ray, this technique increases the cost and complexity of the feeding tube placement. In addition, the use of radiographic imaging exposes the patient to radiation. If the x-ray indicates that insufficient placement was achieved, then the verification process must be repeated following another attempt at placement. This adds still more cost and complexity to the procedure, and further increases the amount of radiation to which the patient is exposed.
Ultrasound visualization is an alternative imaging modality. Ultrasound visualization has favorable characteristics in that it can be performed at the bedside, and it eliminates radiation exposure to the patient. However, the use of ultrasound visualization can be problematic if a volume of air/gas is present between the ultrasound transducer head and a structure being visualized. The gastrointestinal tract has a generally “pipe-like” configuration along much of its length. As the feeding tube advances along the GI tract during insertion, it may track the posterior intestinal wall of this tract, leaving an air gap within the intestinal lumen along the anterior wall. Since the transducer head is positioned on the side of the anterior wall, the presence of the air gap inhibits optimal visualization of the feeding tube under ultrasound.
It would be desirable to provide a feeding tube suitable for placement in the jejunum of the patient, wherein the feeding tube is structured in a manner such that the position of the feeding tube may be viewed by means readily available at the patient's bedside, and by means that do not expose the patient to harmful radiation.
The present invention addresses the shortcomings in the prior art. In one form thereof, a tube is provided for insertion into a body passageway of a patient. The tube includes a generally elongated tubular member having a proximal portion, a distal portion, a lumen extending between the proximal portion and the distal portion, and at least one aperture at the distal portion sized and positioned for passage of fluid material therethrough from the lumen to a target area in the body passageway. The tubular member is structured such that the distal portion is selectively movable between the generally elongated configuration and a shaped configuration. A length of the distal portion comprises an echogenic capability such that the distal portion length is visible under ultrasound visualization in the shaped configuration.
In another form thereof, a method is provided for positioning a feeding tube in the jejunum of a patient. A distal end of a feeding tube is inserted into an oral cavity of a patient. The feeding tube comprises a generally elongated tubular member having a proximal portion, a distal portion having an echogenic surface, a lumen extending between the proximal portion and the distal portion, and at least one aperture at the distal portion for passage of fluid material from the lumen to the jejunum. A stiffening member extends along the tubular member proximal portion and distal portion. The tubular member is selectively maneuverable between the generally elongated condition when the stiffening member extends therealong, and a shaped condition along the distal portion when the stiffening member is withdrawn from the distal portion. The feeding tube distal end is advanced through the stomach of the patient such that the distal portion of the generally elongated tubular member extends into the small intestine of the patient. The stiffening member is withdrawn from the distal portion such that the distal portion maneuvers into the shaped condition. A placement of the shaped distal portion is the viewed via ultrasound visualization of the echogenic surface.
In yet another form thereof, a tube is provided for insertion into a body passageway of a patient. A generally elongated tubular member has a proximal portion, a distal portion, a pair of lumens extending between the proximal portion and the distal portion, and at least one aperture along a length of the tubular member sized and positioned for passage of fluid material therethrough from a first lumen to a target area in the body passageway. The proximal portion of the tubular member has a higher stiffness, and the distal portion of the tubular member has a lower stiffness. The distal portion has an echogenic material disposed therealong. A mandrel is slidably received in a second lumen. The mandrel has a stiffness less than a stiffness of the tubular member proximal portion, and greater than a stiffness of the tubular member distal portion. The mandrel is structured such that a distal length thereof has a tendency to assume a shaped configuration in an absence of restraint thereupon, whereby when the mandrel distal length is received along the tubular member proximal portion having the higher stiffness, the mandrel distal length has the generally elongated condition of the tubular member proximal portion. When the mandrel distal length is received along the tubular member distal portion having the lower stiffness, the mandrel distal length and the tubular member distal portion having the echogenic material disposed therealong assume the shaped configuration.
For purposes of promoting an understanding of the present invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
In the following discussion, the terms “proximal” and “distal” will be used to describe the opposing axial ends of the feeding tube, as well as the axial ends of various component features. The term “proximal” is used in its conventional sense to refer to the end of the feeding tube (or component thereof) that is closest to the operator during use. The term “distal” is used in its conventional sense to refer to the end of the feeding tube (or component thereof) that is initially inserted into the patient, or that is closest to the patient during use.
Feeding tube 10 comprises an elongated tubular member 12 having a distal portion 14. Feeding tubes, such as naso-jejunal tubes, are well known in the art, and tube 10 may be formed from any compositions commonly used and/or appropriate for such purposes. Polyurethane, silicone, polyurethane-silicone copolymers, and PVC are non-limiting examples of such compositions. Typically such tubes have a length of about 150-160 cm, and an outer diameter of between about 8 and 16 French (2.6 to 5.3 mm). Those skilled in the art will appreciate that the length and diameter of a feeding tube may be varied as desired to account for differences in patient size and anatomy.
As shown in
Those skilled in the art will appreciate that additional auxiliary lumens may be provided if desired for other known purposes. Such additional lumens could be used, e.g., to provide an additional fluid source, such as a liquid medication in addition to the liquid nutritional products, and/or to monitor various pressures or functions within the patient's body. An alteration in the number of lumens may necessitate minor alteration in the features of the inventive tube as described herein; however those skilled in the art can readily make such alterations when following the teachings of the present invention.
As shown in
Typically, tubular member 12 tapers to a closed distal end, or tip, 18. When the distal end is closed, all fluid material passes through side ports 16. In addition, a conventional guiding or tracking member (e.g., stiff wire guide, mandrel, or stylet) can be used to aid initial insertion of the tube if desired. In some instances, however, it may be preferred to maintain an open distal end to permit passage of liquid product therethrough. When the feeding tube has an open distal end, the presence of side ports 16 is optional.
Those skilled in the art will appreciate that the feeding tube may include additional features well known in the art. For example, the outer surface of the elongated tubular member may be provided with a series of fin-like projections along the distal portion thereof to enhance the advancement of the feeding tube into the jejunum via peristalsis. Feeding tubes having features that promote self-advancement by peristalsis are further described in, for example, U.S. Pat. Nos. 6,589,213 and 6,767,339, both incorporated by reference herein. Additionally, the feeding tube may be provided with a series of markings displayed at discrete locations along the length of the tubular member to monitor advancement of the tube into the jejunum.
It is sometimes difficult to direct the distal end of a tube to a target site within the anatomy of a patient that is off-set, or has a non-direct path, relative to an entry site. A feeding tube that is intended to be directed into the jejunum of a patient is an example of such a tube. Due to the difficulty in inserting tubes to such sites, it is generally desirable to verify the placement of the tube following insertion. When verifying the placement of a feeding tube in the jejunum, the normal procedure is to transport the patient to the radiology facility to obtain an x-ray. However, this procedure increases the cost and complexity of the feeding tube placement. In addition, the procedure exposes the patient to radiation.
Tube 10 is provided with an echogenic feature that enables the health care worker to observe in real time the location of the end of the tube in a body passageway. This echogenic feature enables tip confirmation to be carried out under ultrasound visualization at the patient's bedside. As a result, there is no need to transport the patient to another location for x-ray verification, and the patient need not be exposed to harmful radiation.
The echogenic feature may be imparted to the tubular member in a variety of ways. In the non-limiting embodiment shown in
Echogenic bands 20A, 20B may be incorporated into tubular member 12 in a variety of ways. For example, the tubular member 12 may be stretched in longitudinal fashion to a smaller diameter, and the band may be inserted thereover. When the stretching is relaxed, tubular member 12 returns to its original diameter, and the band is snugly engaged therewith. Alternatively, respective bands 20A, 20B may be placed within the lumen of the tubular member, and the bands locked in place by melting the tubular member, e.g., during closure of the tubular member distal tip 18 when exposed to heat in a conventional tip-forming device. It is known to fashion bands or rings, such as echogenic bands 20A, 20B onto tubular members, such as catheters, and a skilled artisan can readily fashion a suitable technique for use herein. Tubular members having echogenic bands or sheaths applied thereto are known in the art for other purposes. Examples of catheters having echogenic bands or like enhancements include the ECHOTIP® ureteral catheter, and the ECHOTIP® Soft-Pass Embryo Transfer catheter, both available from Cook Medical of Bloomington, Ind.
The echogenic surface of bands 20A, 20B may comprise a series of irregularities, such as deformations 22, distributed along the exterior surface of the band. Deformations 22 are imperfections that are formed along the surface of the band in a manner that enhances the ability of the band to scatter and/or reflect the ultrasound energy. The deformations may be formed along the length of the band by well-known processes, such as media blasting, physical deformation, machining (e.g., knurling on a lathe), micro-dimpling, etc. Those skilled in the art will appreciate that there are many other ways of forming deformations in a substrate of a type that will result in the scatter and/or reflectance of ultrasound signals, and that may be substituted for the techniques described above. Deformations 22 should be formed in a manner such that they do not adversely affect the mechanical properties of the band in any material fashion.
The presence of the echogenic enhancement, such as deformations 22, causes ultrasound waves that contact the deformations to travel in multiple directions and in generally random fashion. The increase in scatter and/or reflection of the ultrasound waves enhances the temporal visualization of the tip of the feeding tube during ultrasound examination. By viewing the ultrasound signals created thereby, the health care worker may confirm proper tip location. Alternatively, if it is determined upon visualization that the desired tip location has not been achieved, the location of the tube may be adjusted on site.
Feeding tube 10 may be provided in combination with a stiffening member 30, such as a mandrel or a wire guide, as shown in
Tubular member 12 may be formed to have an internal memory, e.g., a shape memory or an elastic memory. In this manner, when mandrel 30 is withdrawn from the lumen, the distal portion 14 of the tubular member curls or is otherwise maneuvered into a pre-arranged, shaped configuration. The shaped configuration preferably includes at least one curve, and more preferably, comprises at least one loop or loop-like configuration 17 (collectively referred to herein as a “loop”), as shown in
Those skilled in the art are aware of many suitable processes for preparing a substrate to be capable of taking on a pre-arranged shaped configuration as described. One preferred way of treating a tubular member to return to a shaped configuration is by heat setting a specified distal length of the tubular member. This may be carried out, e.g., by placing the specified tubular member distal length in a heated glycerin solution to soften the polymer, and thereafter placing the heated portion of the tubular member in a suitably-shaped mold. Upon cooling, the designated portion of the tubular member takes on the desired configuration. In this manner, the tubular member can be temporarily straightened for insertion into a body opening, e.g., by insertion of the stiffening member into the tubular member lumen as described. Once the tubular member is advanced to the target site, the stiffening member is removed, and the tubular member will revert to the pre-arranged shaped configuration.
Any number of echogenic members can be applied to the tubular member, and the members can be spaced at varied lengths along the tubular member. In the non-limiting embodiment shown in
Although the embodiment shown in
Although loop 17 has been described above as formed via a heat-set of the distal portion of the tubular member, those skilled in the art will appreciate that there are other suitable ways to achieve a desired shaped configuration for a designated length of a catheter or other tubular member.
The proximal end of tension member 32 preferably extends beyond the proximal end of feeding tube 10 to enable easy grasping and drawing of the tension member in the proximal direction to form a desired shaped configuration, such as a loop configuration. When the desired shaped configuration is achieved, the tension member may be knotted, or locked in a suitable locking mechanism (not shown) to maintain the shaped configuration. Locking mechanisms suitable for use with tension members to lock a portion of a catheter or like device into a desired shaped configuration are well known in the art, and need not be further described. Such mechanisms are commonly utilized in connection with, e.g., drainage catheters and the like which are often drawn into a looped configuration and locked therein. One example of such a locking mechanism is provided in U.S. Pat. No. 5,399,165, incorporated by reference herein.
In one embodiment, the two techniques described above may be combined. That is, the tubular member may be heat set to achieve the looped configuration shown in
In the example depicted in
Initially, the distal end of tube 10 is inserted into an oral cavity of the patient (e.g., nose or mouth), and advanced about 50-70 cm into the stomach. As stated above, a guiding or tracking member (e.g., stiff wire guide, mandrel, stylet) may be inserted into the tube prior to placement to assist in insertion into the stomach. Insufflation and/or auscultation may be used to confirm the position of the distal tip of tube 10 in the stomach.
At this time, the feeding tube is advanced through the stomach of the patient such that the distal portion of the generally elongated tubular member extends into the small intestine of the patient. Typically, the distal end portion 14 of the feeding tube is advanced into the small intestine via peristaltic activity along the GI tract.
As shown in
Following further advancement, the clinician may again investigate whether appropriate placement of the distal portion 14 has been achieved. As shown in
In some cases, the clinician may assume that notwithstanding the lack of an optimal ultrasound image due to the air gap, appropriate placement has been attained. This assumption may be formulated from past experience in feeding tube placement, or alternatively, by monitoring the length of feeding tube that has been inserted (e.g., by viewing spaced markings along the length of the feeding tube). In order to minimize the possibility of an erroneous reading due to the air gap AG as shown in
Feeding tube 102 includes one or more feeding tube side ports, or apertures, 106 disposed along the length of the feeding tube to permit passage of nutritional products from lumen 110 into the jejunum in well-known fashion. In this non-limiting embodiment, six ports 106 extend through the feeding tube 102 along each side thereof. Those skilled in the art will appreciate that more, or fewer, side ports may be provided if desired, and that the side ports may be aligned along the feeding tube in any desired arrangement. As with feeding tube 10, feeding tube 102 will preferably taper to a closed distal tip 108.
Distal portion 104 comprises the distalmost length of the tubular member, and preferably, the distalmost 5 to 13 cm of the tubular member. Feeding tube 102 is formed from one or more compositions arranged such that distal portion 104 has a lower durometer (i.e., is more flexible) than proximal portion 103. Those skilled in the art are aware of various methods of forming a feeding tube to have a lower durometer distal portion. For example, the tube can be extruded in a continuous operation such that designated portions of the tube can be of different durometer. With continuous extrusion, a tubular member can be extruded in well-known fashion to be, e.g., rigid or semi-rigid at one end and more flexible at the other end. The tubular member can be extruded to provide a gradual durometer decrease over a defined length of the tube, or can be extruded to provide as many segments of different durometer as desired. Alternatively, a tube having a first durometer can be bonded in well-known fashion (e.g., thermal bonding) to a tube having a second durometer. For optimal bonding, the proximal portion 103 and the distal portion 104 are preferably formed of the same or a similar polymer (e.g., a polyether block amide, such as PEBAX®). However, the proximal portion and distal portion need not necessarily be formed of the same or a similar polymer, as long as they are formed of compositions capable of securely being affixed to each other, e.g., by bonding or adhesion.
Preferably, mandrel 120 is formed of a surgical grade alloy wire, e.g., a shape memory or superelastic wire such as nitinol. Shaped distal end 122 may be straightened as described herein, such that straightened mandrel 120 can be received in tubular member lumen 112, as shown in
As stated, the feeding tube is formed of one or more compositions (e.g., a polyurethane, a polyether block amide, etc) wherein the proximal end has a higher durometer than the distal end. If desired, the proximal end of the feeding tube can be reinforced with, e.g., a wire coil or braid as shown in U.S. Pat. No. 5,380,304, incorporated by reference herein, to provide added stiffness such that the mandrel can readily conform to the shape of the proximal portion of the tube. The distal end of the feeding tube will preferably not be reinforced, thereby allowing it to readily take on the pre-determined shape of the mandrel once the mandrel is advanced into the distal end.
In
In
Echogenic enhancing features are provided along tubular member distal portion 104. In the non-limiting embodiment of
Those skilled in the art will appreciate that feeding tube assembly 100 may be advanced into the small intestine, and arranged therein to provide real-time ultrasound visualization in a manner generally similar to that shown and described hereinabove with reference to
At this time, the ultrasound transducer head can be aligned externally of the patient as described above, and a real-time ultrasound image is obtained. If the quality of the image is not deemed suitable, the clinician can simply further advance the assembly along the small intestine, and obtain another ultrasound image.
While these features have been disclosed in connection with the illustrated preferred embodiments, other embodiments of the invention will be apparent to those skilled in the art that come within the spirit of the invention as defined in the following claims.
