The present invention relates to an assembly for guiding positioning of a needle tip within tissue by enhancing the sensitivity of ultrasound visualization and more particularly to an assembly improving the accuracy of renal puncture procedures.
Percutaneous nephrolithotomy (PCNL) is standard of care for large renal stone burdens such as >20 mm. Renal collecting system puncture is a critical step in PCNL as it gives the surgeon access to the kidney stone in a minimally invasive method. While fluoroscopy has been the puncture technique of choice, adoption has been limited because obtaining a perfect puncture is technically challenging. PCNL is considered an “advanced” endourological procedure that only 27% of American urological surgeons trained in PCNL continue to use, with only 11% of American urologists performing PCNL routinely themselves. Instead, the renal puncture access is relegated to radiologists, and although radiologists are able to gain access, their involvement complicates the procedural logistics and, theoretically, adds morbidity through the employment of a second, separate procedure.
When the renal puncture is performed by the urologist, it is commonly performed simultaneously as part of the PCNL procedure. Fluoroscopic guidance is the primary technique used since the 1970's. More recently, the introduction of ultrasound assisted renal puncture has become more commonplace. See, e.g., Iordache, A., et al., Med Ultrason 2018, 20(4): 508-14). Benefits of ultrasound assisted renal puncture include absence of ionizing radiation for both patient and provider, ability to identify other organs (minimizing complications), and easier appreciation of the posterior calyx. (Usawachintachit, M., et al., J Endourol 2016 30(8).)
Despite these advantages, there is a reticence to adoption of ultrasound assisted renal puncture. In addition to having to learn an imaging technique that most urologists are not familiar with, there is the added difficulty of visualizing the placement of the needle during the puncture. The needle has poor echogenicity and its echogenicity varies with surrounding tissue density (patients can have different tissue density). In aggregate, this adds to hesitancy to adopt a technique whose primary limitation is visualization. We therefore propose a unique needle with significantly improved visualization. The incorporation with PCNL potentially assists in the diffusion and adoption of ultrasound assisted renal puncture.
According to embodiments of the invention, a modified needle and sheath system is used to gain access to the renal calyx under ultrasound guidance. The inventive needle/sheath combination is inserted through the skin and kidney into the renal calyx. The needle is then removed and a guidewire inserted through the sheath into the renal calyx to allow access to the renal calyx of other instruments. The benefit of the inventive approach is that it allows improved visualization of the tip of the needle/sheath in the renal calyx using ultrasound as a guidance modality.
In some embodiments, the invention uses air as a means for visualization of the tip of the needle. The air or ultrasound contrast media, such as perflutren, is injected in a chamber at the distal end of the needle/sheath and forced through the sheath over the needle to exit the sheath at the end of the needle. Air bubbles are very echogenic—the bubbles exiting the end of the sheath provide an ultrasonically visible landmark.
Features of the invention include a chamber at the distal end of the needle/sheath that allow injection of air. The chamber is located at the distal end of the sheath, but the needle passes through the chamber and is sealed to form an fluid tight seal at the end of the needle sheath combination. The fluid tight feature of the needle to the chamber is critical as it forces the air/contrast media injected into the chamber to exit at the distal end of the needle/sheath. Although the seal between the needle and chamber must be fluid tight, it must also allow the needle to be removed from the chamber to allow a guidewire to be inserted through the chamber and sheath, into the renal calyx. The introduction of air/media into the chamber may be accomplished manually, such as by using a syringe, or automatically using equipment that could supply a metered dose of air or contrast media.
Another feature of the inventive system is the shape of the needle in the chamber and the sheath. The needle is shaped to allow air/fluid flow along its length in the sheath. The normal gap defined between needle and sheath is narrow enough to restrict transport of air/fluid to the proximal end of the needle/sheath. The normally cylindrical needle may be modified to remove a portion of the needle, for example, by flattening a portion of the needle or machining a longitudinal channel along the length the needle. At the distal end of the sheath, where the needle may extend a short distance to end in a point. Additional modification of the needle may include, for example, an annular channel formed near the distal end may enhance uniform radial distribution of air/media at the end of the sheath. Further modifications may include grooves emanating from the annular channel. inside the sheath. Selection of the size/depth of the grooves provide control of the size of the bubbles generated at the end of the sheath.
In a first aspect of the invention, an assembly for facilitating ultrasonic visualization of positioning of a needle inserted into tissue includes a needle having a needle length; a sheath having a sheath length and configured for concentrically receiving the needle, the sheath having a sheath head disposed at a proximal end configured for introducing fluid into a transport channel defined between an outer surface of the needle and an inner surface of the sheath, where the transport channel includes features configured for inducing formation of ultrasonically visible features at a distal end of the sheath; and a fluid source in fluid communication with the sheath head for introducing fluid under pressure. In some embodiments, the transport channel comprises at least one longitudinal channel formed in the inner surface of the sheath. The at least one longitudinal channel may be a plurality of longitudinal channels extending along the sheath length. These longitudinal channels may be defined by ribs extending radially inward from the inner surface of the sheath. In another implementation, the at least one longitudinal channel are a plurality of longitudinal channels shorter than the sheath length disposed near the distal end of the sheath. The sheath may include a plurality of radial openings located near a distal end of the sheath. In still other embodiments, the transport channel may be at least one longitudinal channel formed in an outer surface of the needle. In some configurations, the at least one longitudinal channel may extend a partial length of the needle to intersect with an annular channel configured to direct the fluid radially outward from the needle. The annular channel may be disposed at a position along the needle length corresponding to the distal end of the sheath, or it may be disposed at a position along the needle length that is less than the full sheath length, and the sheath may have a plurality of radial openings disposed to align with the annular channel. The annular channel may be disposed at a position along the needle length that is less than the full sheath length, and wherein the sheath may have a plurality of tapered grooves formed on the inner surface, where each groove has a first end that aligns with the annular channel and a second end that extends to the distal end of the sheath. A plurality of tapered grooves may be disposed near a distal end of the needle, where the tapered grooves extend distally from the annular channel.
In some embodiments, the longitudinal channel may be formed by flattening a side of the needle or by forming a groove in the outer surface of the needle. In most embodiments, the needle length is greater than the sheath length. The fluid may be air or a contrast media suspension.
In another aspect of the invention, a method for visualizing positioning of a needle inserted into tissue, comprising inserting into a target tissue the assembly described above, and using an ultrasonic imaging instrument to generate an image of ultrasonically visible features at the distal end of the sheath.
In still another aspect of the invention, an assembly for facilitating ultrasonic visualization of positioning of a needle inserted into tissue includes: a sheath having a hollow tubing having a sheath length and a sheath end, the sheath having a sheath head disposed at a proximal end configured for introducing fluid into the sheath; a needle concentrically disposed within the sheath to define a transport channel between an outer surface of the needle and an inner surface of the sheath, wherein the transport channel comprises features configured for inducing formation of ultrasonically visible features at a distal end of the sheath; and a fluid source in fluid communication with the sheath head for introducing fluid under pressure. In some embodiments, the transport channel comprises at least one longitudinal channel formed in the inner surface of the sheath. The at least one longitudinal channel may be a plurality of longitudinal channels extending along the sheath length. These longitudinal channels may be defined by ribs extending radially inward from the inner surface of the sheath. In another implementation, the at least one longitudinal channel are a plurality of longitudinal channels shorter than the sheath length disposed near the distal end of the sheath. The sheath may include a plurality of radial openings located near a distal end of the sheath. In still other embodiments, the transport channel may be at least one longitudinal channel formed in an outer surface of the needle. In some configurations, the at least one longitudinal channel may extend a partial length of the needle to intersect with an annular channel configured to direct the fluid radially outward from the needle. The annular channel may be disposed at a position along the needle length corresponding to the distal end of the sheath, or it may be disposed at a position along the needle length that is less than the full sheath length, and the sheath may have a plurality of radial openings disposed to align with the annular channel. The annular channel may be disposed at a position along the needle length that is less than the full sheath length, and wherein the sheath may have a plurality of tapered grooves formed on the inner surface, where each groove has a first end that aligns with the annular channel and a second end that extends to the distal end of the sheath. A plurality of tapered grooves may be disposed near a distal end of the needle, where the tapered grooves extend distally from the annular channel.
In some embodiments, the longitudinal channel may be formed by flattening a side of the needle or by forming a groove in the outer surface of the needle. In most embodiments, the needle length is greater than the sheath length. The fluid may be air or a contrast media suspension.
The inventive needle and sheath assembly facilitates visualization to allow accurate placement of the sheath tip within tissue via ultrasonic imaging. In some applications, the assembly is used to introduce air into the tissue where it forms bubbles at the sheath tip. In other applications, an ultrasound contrast media, for example, perflutren, a suspension of lipid microspheres, i.e., particles, is transported by the assembly for release at the sheath tip. With either material, the bubbles of air or particles of contrast media are highly echogenic, producing an ultrasonically visible landmark at their location at the end of the sheath. For purposes of this disclosure, the term “fluid means the air or contrast media suspension that is transported by the assembly. “Ultrasonically-visible features” are air bubbles, microbubbles, contrast media particles, masses, or similar elements that exit the sheath after manipulation of the fluid by structures within the assembly to form echogenic features (e.g., bubbles, particles, areas) within the tissue around the sheath tip which can be visualized using ultrasound.
Hollow sheath 12, shown in
Referring to
As illustrated in
Referring to
The structures and relationships shown in and described with reference to
The injection occurs at the proximal end of the sheath body and the fluid travels along the length of the needle and interior of the sheath to exit the distal end of the needle/sheath combination.
In some embodiments, the corresponding needle may have a continuous surface (non-grooved) outer diameter that closely fits within the spacing between opposing ribs 64. The ribs may extend down the entire length of sheath 60, so that the air/media exits the distal end 61 of the sheath through the multiple gaps 66 defined by the ribs. In the illustrated example, In another implementation, the needle shown in
The embodiments shown in
Needle 82 shown in
The following examples provide illustrative descriptions of the methods of use of the inventive assembly
A prototype design of the needle/sheath assembly was built and tested to determine the function and efficacy of the system. A piece of meat, a 3-pound chuck roast, with a hollow interior area representing the renal calyx was used to simulate the function of the current device in a clinical environment. A BK Medical (Herlev, Denmark) imaging system with a multi-array probe was used for ultrasound visualization and guidance. A water-based hydrogel was used between the probe and the meat.
The guidance of the invention into the cavity of the roast was complicated by the reverberation and reflection of the needle as it passed through the meat. This phenomenon creates multiple images of the needle, making it difficult determine which image is the real needle image and its location in relationship to identifiable landmarks. Referring to
In step 102, the user (or an assistant) inserts the needle 21 into sheath head 13 and sheath 12 until needle stopper 22 fits into bore 17 and the distal end 25 of needle 12 extends from the sheath tip. In step 103, the user inserts the needle and sheath through the exterior of the target tissue to the approximate location of the desired treatment. A skilled practitioner would be expected to be relatively accurate in the placement at this point, however, the object of the invention is to enhance accuracy of the ultimate positioning for the procedure, and to make it easier for a less experienced user to accurately position the device. Preparations are made for ultrasonic imaging of the target area, and in step 104, an injector 30 connected to a fluid source is attached to port 19 of sheath head 13 and the fluid is injected into sheath head 13 so that it is forced into the transport channel between the needle 21 and the inner surface of sheath 12 to the distal end of sheath 12 where bubbles are formed. Concurrently with step 104, the imaging procedure of step 105 begins to visualize the appearance of bubbles from the end of the sheath. Using this visualization, the user confirms in step 106 that the sheath and needle are positioned at the desired location. In step 107, if the correct positioning is not indicated by the ultrasound image, the user may move and/or partially retract the assembly and repeat step 103 to reposition the assembly based on the location information obtained during initial imaging step 105. Steps 106 and 107 are repeated if necessary until the correct position is achieved. In step 108, the fluid connection is detached and the tubing withdrawn to clear the area of obstacles not required for the procedure. For procedures in which additional actions are to be performed, for example, if a nephroscope is to be inserted, or an ultrasonic or laser probe is to be used for inserted for treatment, in step 109, the needle is withdrawn and a guidewire or other instrument may be inserted into the sheath over which other instruments may be passed into the renal calyx to perform other actions.
The inventive assembly defines a transport channel between a needle concentrically and removably disposed within a sheath. Features are formed within the channel induce break up of air or contrast media that has been introduced into the transport channel to form bubbles or other echogenic areas. The bubble-inducing features may be formed in the needle, the sheath, or a combination thereof. The embodiments described herein provided illustrative examples of different combinations of features that can be used to achieve the object of generating bubbles or echogenic features for visualization using ultrasonic imaging techniques. The different combinations of components and features described herein are not intended to be limiting, and as will be readily apparent to those in the art, components described with reference to one combination may be utilized in combination with other components without deviating from the overall invention.
This application claims the benefit of the priority of U.S. Provisional Application No. 63/074,822, filed Sep. 4, 2020, which is incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US2021/049308 | 9/7/2021 | WO |
Number | Date | Country | |
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63074822 | Sep 2020 | US |