Patent Application
20230200846
The present invention relates generally to medical devices. More particularly, the present invention relates to an extendable needle.
Over 11 million epidural anesthesia procedures are performed each year in the U.S. Most procedures begin with insertion of a standard 3.5″-long Tuohy (or Husted) needle. This length is often inadequate in reaching the epidural space of patients with a body mass index (BMI) of more than 30. Over the past few decades, obesity rates have been growing in the U.S. In the early 1990s, the rate was 23% for adults aged 20 and older; in 2016, the rate is 40%. Additionally, it is estimated that by 2030, roughly one-half of all men and women in the U.S will be obese. Unfortunately, when performing epidural anesthetics on obese or overweight patients, anesthesiologists face increased difficulty, failure rate, and time delays of the surgical procedure.
Anesthesiologists report that when attempting to insert a needle of inadequate length, it is routine (and often futile), to restart the procedure: choosing an anatomic space more rostral to the original, re-injecting intradermal local anesthesia, and reinitiating insertion of the needle. This makes the procedure more uncomfortable for the patient. At some hospitals, a longer needle may be available. However, substantial time is added to the procedure as the needle is retrieved and the procedure is reinitiated. This increases the cost of operating room time and risk of infection as the anesthesiologist removes sterile gloves, empties the sterile package containing the longer length needle onto the sterile field, and then immediately re-gloves. In addition, the sterile field is now open for an extended period of time, sometimes in an area considered non-sterile (e.g., labor room).
Finally, if longer needles are unavailable, the epidural technique is abandoned contributing to frustration for the anesthesiologist, anxiety and often unrelieved pain for the patient. As shown in
Therefore, it would be advantageous to provide a device for performing epidural anesthesia on patients with a long skin-to-epidural space distance.
The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect a device assembly includes a hub having inner and outer sheaths that are configured to telescope with respect to one another. The device includes a locking mechanism configured to lock the hub into an extended or retracted position. The device also includes a needle that is lengthened based on the hub being extended or retracted.
In accordance with an aspect of the present invention, the locking mechanism includes protrusions for engaging the hub. The inner sheath includes indentations for coupling with the locking mechanism. The locking mechanism is rotated about the inner sheath in order to further engage the indentations. The outer sheath comprises wings.
In accordance with another aspect of the present invention, a device assembly includes a hub having inner and outer sheaths that are configured to telescope with respect to one another. The device also includes a locking mechanism configured to lock the inner and outer sheaths of the hub into a predetermined configuration. Additionally, the device includes a needle that is lengthened based on a position of the hub as extended or retracted.
In accordance with still another aspect of the present invention, the locking mechanism includes an internal protrusion for engaging the hub. The inner sheath includes indentations for coupling with the locking mechanism. The locking mechanism is rotated about the inner sheath in order to further engage the indentations. The outer sheath includes wings. The wings are configured to move towards the physician, when the needle is extended. The inner and outer sheaths lock in the retracted position with rotational movement with respect to one another. A rotational structure of the device is limited to the hub such that rotational locking and unlocking of the inner and outer sheaths does not rotate a shaft of the needle. The needle is smooth along its entire surface whether in the non-extended or extended position. The inner and outer sheaths telescope slidably with respect to one another. The locking mechanism includes an outer tab for removal. The locking mechanism is configured to lock the inner and outer sheath together in a retracted position. The locking mechanism is configured to lock the inner and outer sheath together in an extended position.
In accordance with yet another aspect of the present invention, a device assembly includes a hub having inner and outer sheaths that are configured to telescope with respect to one another. The inner and outer sheaths are further configured to lock in an extended or retracted position. The device includes needle that is lengthened based on a position of the hub as extended or retracted.
In accordance with still another aspect of the present invention, the outer sheath includes wings. The wings are configured to move towards the physician, when the needle is extended. The inner and outer sheaths lock in the retracted position with rotational movement with respect to one another. A rotational structure of the device is limited to the hub such that rotational locking and unlocking of the inner and outer sheaths does not rotate a shaft of the needle. The needle is smooth along its entire surface whether in the non-extended or extended position.
The accompanying drawings provide visual representations, which will be used to more fully describe the representative embodiments disclosed herein and can be used by those skilled in the art to better understand them and their inherent advantages. In these drawings, like reference numerals identify corresponding elements and:
The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying Drawings, in which some but not all embodiments of the inventions are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may 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 satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
The Tuohy needle of the present invention includes a hub design that allows for the needle to be extended mid-procedure from 3.5″ to 5″. The extendable needle of the present invention allows practitioners to better accommodate overweight and obese patients and introduce a simpler procedure workflow.
Patient and physician needs and market trends were investigated through expert interviews and physician shadowing. Based on numerical data regarding the barriers to market entry, observational data from shadowing sessions, and physician interviews, the following design requirements were established for a new needle design:
The need for a longer needle for obese patients, who have a larger corresponding skin-to-epidural depth, is clearly demonstrated since the 3.5″ standard is not long enough to traverse the longer depths associated with BMI≥30. However, starting the procedure with the longest epidural needle is also not recommended since longer needles are harder to manipulate and are more difficult to control. During clinician interviews, it was emphasized that the extraneous length of the needle outside of the patient's back can also pose the risk of having healthcare practitioners unintentionally jar the needle. Therefore, patients need an ideal epidural needle length that is not too long and not too short.
Two aspects of the design were tested. First, the integrity of the locking mechanism was tested in enduring extreme axial force encountered during an epidural anesthesia procedure. Second, design usability was tested by conducting a usability study that provides physician feedback on the prototype. The axial force test was completed using Finite Element Analysis. A safety factor of 2 was assumed to ensure that a real design would not fail unless the actual stress was half the lowest stress resulting in material failure (as Safety Factor=Material Strength/Actual Stress). To maintain needle durability during maximum stress of the procedure (17 N), the material strength, or maximum allowable stress, was chosen to be twice this value. A Margin of Safety=Safety Factor −1 correction factor was employed, yielding a Safety Factor threshold of 3. This threshold allows twice the applied load (perpendicular to hub) to be added to the applied load before failure begins to occur.
During the usability study, physicians were asked to use the prototyped needle hub, in conjunction with a Tuohy needle, on a spine model. Physicians will follow a procedure that guides them through the extension of the device. Physicians will be asked to comment on the intuitiveness of the procedure and device. After completing the procedure on the spine model (which serves as a makeshift obese patient), physicians fill out a questionnaire to provide input on usability of the device and whether the solution concept is compatible with select design requirements.
First, the locking mechanism was tested, using polypropylene parameters, to withstand 17 N during finite element analysis through Fusion 360.
Anesthesiologists were asked to use the extendable epidural needle on a spine model and to critique various aspects of its usability. In the questionnaire, physicians are inquired about the ease-of-use of the device, how it would change the current workflow, and how it would affect risk of contamination, time of procedure, and patient comfort. The anesthesiologists were given a 3D-printed (VeroClear and Rigur) prototype of the extendable needle. They were instructed to perform a mock epidural anesthetic on a spine model: insert the epidural needle, extend the needle, thread a catheter, and withdraw the needle over the catheter.
Table 1 lists questions and physician responses. Results demonstrate that there would be either no change or a slight decrease in procedure difficulty and risk of infection. Additionally, anesthesiologists believed that the use of the device would lead to a decrease in procedure time and increase in patient comfort. Suggestions for improvement included introducing an auto-locking mechanism to avoid needle instability while re-locking the needle after its extension, incorporating a transparent Tuohy needle hub, and interchanging the locking and unlocking directions. Overall, the results from this survey indicate that an extendable Tuohy needle might improve patient and physician experience during an epidural anesthesia procedure performed on obese patients.
Based on the results of the usability survey, the concept and design seem to be favorable for anesthesiologists. The design of an extendable needle potentially has applications to other anesthetic procedures (such as peripheral nerve blocks) and to other fields of medicine, in which extendable needles/tubing would be useful for aspiration of tissue/fluid (e.g. biopsy), injection of a drug or threading of a catheter.
Responses to the questionnaire indicate that the prototype design did not threaten to increase risks of contamination or difficulty of overall procedure, and could potentially reduce procedure time and increase patient comfort/decrease patient discomfort. Nonetheless, based on the results of questionnaire and physician feedback, in future design revisions, several considerations could be made. As all anesthesiologists answered that the design neither complicates nor eases the procedure, the device and procedure should be simplified. To this end, an auto-locking mechanism could be developed, allowing the ring mechanism to “self-lock” after the outer sheath is retracted. Incorporation of a transparent hub would allow physicians to see standard one-centimeter markings on the catheter during catheter threading and withdrawal of the needle over the catheter. Interchanging the design's locking and unlocking directions, thus making a counterclockwise turn an unlocking motion and a clockwise turn a locking motion, could also increase the design's intuitiveness.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
This application is a 35 U.S.C. § 371 U.S. national entry of International Application PCT/US2021/017105, having an international filing date of Feb. 8, 2021, which claims the benefit of U.S. Provisional Application No. 62/971,411, filed Feb. 7, 2020, the content of each of the aforementioned applications is herein incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/017105 | 2/8/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62971411 | Feb 2020 | US |
