Patent Publication Number: US-2021161374-A1

Title: Disposable Speculum for Digital Otoscope

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/281,665 filed Feb. 21, 2019, and hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a speculum for an otoscope, and in particular, to a speculum that is insertable into an ear canal and surrounds an electronic camera of the otoscope extending along an axis of the speculum to retrieve images of the ear canal. 
     An otoscope is a medical device allowing a healthcare professional to inspect the ear canal and tympanic membrane (eardrum). A simple otoscope provides for a hollow funnel-shaped speculum whose small end is inserted into the ear canal. The purpose of the funnel shape of the speculum is to provide a visual path to the tympanic membrane and to assist in controlling depth of insertion of the speculum. The speculum also provides a clean barrier between the otoscope and the patient. 
     Modern otoscopes include an internal source of illumination directed down the speculum axis from a contained battery-operated lamp and may provide a magnifying lens supported outside the ear and aligned with the axis of the speculum to provide an enlarged image of the ear structure being viewed. The speculum may be desirably disposable and normally includes a threaded attachment provided by a short spiral groove on a receiving portion of the otoscope. 
     More recently, otoscopes have incorporated digital cameras with displays directly on the otoscope for viewing the camera image. An example of these otoscopes is found in U.S. Pat. No. 9,326,668, US patent publication 2016/0374546, US patent publication 2018/0125345, assigned to the present applicant, each of which is hereby incorporated by reference. In such otoscopes, a digital camera may be positioned at the end of a probe that is inserted into the ear. 
     SUMMARY OF THE INVENTION 
     The present inventors have recognized that the conventional spiral groove threads used to attach disposable speculums to otoscopes can be suboptimal for digital otoscopes where the axial tip of the speculum must be precisely located to protect the camera without unduly limiting its field-of-view. The spiral engagement of threaded systems can also hamper the use of probes or tools attached to the speculum where precise rotational position and resistance to torque is important. 
     The present invention provides a disposable speculum for an otoscope that provides a sheath adapted to cover an elongate otoscope probe and providing inwardly extending tabs that are adapted to flex outward when the speculum is inserted over the otoscope to releasably engage corresponding grooves of the otoscope. 
     Specifically, then, in one embodiment, the invention provides a disposable speculum for an otoscope including a funnel-shaped sheath having a central bore sized to receive an elongate cylindrical probe element of the otoscope therein along an axis and having a distal end sized to fit within an ear canal and a proximal end providing radially inwardly extending teeth flexible outwardly to allow the inwardly extending teeth to releasably engage corresponding grooves of the elongate probe element of the otoscope by an outward movement of the teeth. 
     It is thus a feature of at least one embodiment of the invention to provide an attachment mechanism that facilitates precise rotational position and axial extension of the axial tip of the speculum to protect the axially extending camera therein. The snap on attachment mechanism provides an intuitive sense of rotational positioning compared to screw type speculums where rotational position may be important, such as when the speculum includes a scraper tool. 
     The teeth may be flanked by axial slots allowing portions of the proximal end holding the teeth to flex outwardly. 
     It is thus a feature of at least one embodiment of the invention to provide an engagement mechanism that does not require rotation of the speculum during attachment. 
     The teeth may have front faces facing toward the distal end and that extend inwardly perpendicular to the axis or canted toward the distal end as one moves inwardly along the front faces. 
     It is thus a feature of at least one embodiment of the invention to provide teeth that resist axial dislodgement after the teeth engage the corresponding grooves. 
     Three teeth may be equally spaced at 120° about the axis. 
     It is thus a feature of at least one embodiment of the invention to provide an attachment mechanism that better resists two dimensions of torsion across the insertion axis and perpendicular to an axis of the probe. 
     The circumferentially opposed ends of the teeth may provide at least one inwardly sloping wall as one moves radially inwardly along the tooth. 
     It is thus a feature of at least one embodiment of the invention to decrease contact pressure between teeth and sloped walls of the grooves of the otoscope when the speculum is rotated for release and disposal. 
     The proximal end may provide a circular rim and the axial slots extend through the rim. 
     It is thus a feature of at least one embodiment of the invention to provide good outward flexibility of the teeth with simple injection molding techniques. 
     The proximal end may include a cylindrical portion abutting and supporting the cylindrical probe element. The speculum may further include a tapered portion beyond the cylindrical portion. 
     It is thus a feature of at least one embodiment of the invention to maximize camera support while reducing tip width required for insertion into the inner ear. 
     The speculum may further include radially outwardly extending fins rotationally aligned with the teeth. 
     It is thus a feature of at least one embodiment of the invention to place rotational force directly over the teeth for improved release of the teeth during rotation of the speculum and provide controlled stiffness of flex independent of thickness of the speculum wall. 
     The sheath may be a thermoplastic material. 
     It is thus a feature of at least one embodiment of the invention to provide a speculum that is easy to manufacture and thus inexpensive to be disposable for improved safety. 
     The sheath may be light absorbing. 
     It is thus a feature of at least one embodiment of the invention to prevent unwanted light leakage into the sheath that may affect the camera images. 
     The sheath may further include an otoscope housing adapted for support by a hand of a healthcare professional with the housing in an inspection position adjacent to an outer ear of a patient wherein the elongate cylindrical probe element has a proximal end supported by the housing so that a distal end of the elongate cylindrical probe element may extend along the axis into the ear canal; and an otoscope electronic camera supported by a distal end of the elongate cylindrical probe element for viewing into the ear canal when the distal end of the elongate cylindrical probe element is positioned in the ear canal of the outer ear. 
     It is thus a feature of at least one embodiment of the invention to install the speculum over an otoscope desiring extension of a camera tip into the ear canal. 
     The corresponding grooves may be radially spaced at 120° about the axis. 
     It is thus a feature of at least one embodiment of the invention to align the teeth with the grooves by slight (less than a quarter turn) rotation of the speculum. 
     The corresponding grooves may include a ramp surface. 
     It is thus a feature of at least one embodiment of the invention to allow for disengagement of the speculum by rotation of the speculum followed by separation of the speculum and otoscope along the axis. 
     The corresponding grooves may include a front perpendicular face. 
     It is thus a feature of at least one embodiment of the invention to provide abutment of the teeth against the front face of the groove to resist dislodgement of the speculum. 
     A distance between a distal end of the sheath and a distal end of the elongate probe element may be approximately 1 mm to 2 mm. 
     It is thus a feature of at least one embodiment of the invention to provide fixed axial alignment of the speculum extending over the fragile axially extending camera. 
     In an alternative embodiment, the present invention provides method of using a disposable speculum for an otoscope including the following steps: providing a funnel-shaped sheath having a central bore sized to receive an elongate cylindrical probe element of the otoscope therein along an axis and having a distal end sized to fit within an ear canal and a proximal end providing radially inwardly extending teeth allowing the teeth to flex outwardly to allow the inwardly extending teeth to releasably engage corresponding grooves of the elongate probe element of the otoscope by an outward movement of the teeth; and inserting the sheath into the ear canal. 
     These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of a disposable speculum constructed according to the present invention being inserted onto an otoscope along an insertion axis; 
         FIG. 2  is a perspective view of an exterior of the disposable speculum of  FIG. 1  providing a sheath presenting a flexing collar tapering to a cylindrical tube; 
         FIG. 3  is a perspective view of an interior of the disposable speculum of  FIG. 2  showing multiple teeth flexing outwardly with the flexing collar; 
         FIG. 4  is a cross-sectional view, along a vertical plane along lines  4 - 4  of  FIG. 1 , through the speculum and assembled otoscope of  FIG. 1 ; 
         FIG. 5  is an enlarged cross-sectional view similar to  FIG. 4  showing a tooth received into a groove of the otoscope having substantially perpendicular side walls; and 
         FIG. 6  is an enlarged cross-sectional view, along a vertical plane along lines  6 - 6  of  FIG. 4 , perpendicular to the insertion axis of the otoscope showing the tooth received into the groove of the otoscope having at least one ramped side wall. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to  FIG. 1 , a removable speculum  10  of the present invention may provide a protective sheath  12  that fits over a cylindrical probe  14  of an otoscope  16  extending along an insertion axis  20  that aligns with the ear canal when the otoscope  16  is used. The otoscope  16  may support on its distal probe tip  17  a front facing electronic camera  18  for acquiring multi-pixel, three-color images in a field of view directed along a speculum axis  22 . An otoscope  16  suitable for use with the present invention is described in U.S. Pat. No. 9,326,668, US patent publication 2016/0374546, and US patent publication 2018/0125345, each of which is hereby incorporated by reference. 
     The removable speculum  10  is attached to the otoscope  16  by a snap lock engagement between the protective sheath  12  and the otoscope  16  supporting the cylindrical probe  14  and electronic camera  18  as further described below. 
     Referring now to  FIG. 2 , the protective sheath  12  of the removable speculum  10  may be in the form of a hollow trumpet with a central bore extending along the speculum axis  22  and surrounded by the outer sheath  12 . The outer sheath  12  is generally radially symmetric at 120 degrees of rotation with progressively increasing amounts of outward flaring along the speculum axis  22  as the sheath  12  flares upward from a distal speculum tip  11  to a circular, outer proximal rim  13  attached to the otoscope  16 . An outer diameter of the outer sheath  12  may progressively increase from approximately 2-3 mm of the distal speculum tip  11  to approximately 18-19 mm of the outer proximal rim  13 , or progressively increase by 6 to 10 times its minimum diameter. 
     The outer sheath  12  may be constructed of a non-elastomeric thermoplastic by injection molding. The rigid material of the protective sheath  12  allows the speculum  10  to easily slide over the cylindrical probe  14  without the resistance that might be expected, for example, if the material were an elastomer. The rigid material of the protective sheath  12  also serve to support and protect the relatively fragile cylindrical probe  14  and electronic camera  18 . The speculum  10  may be opaque and may be light absorbing, such as black in color, to minimize light leakage into the sheath  12 . 
     A distal portion  33  of the protective sheath  12  extending into the ear canal may provide an elongate tube  34  having a central bore extending along the speculum axis  22 , with an inner diameter, measured in a plane perpendicular to speculum axis  22 , of approximately 2-3 mm and less than 3 mm and desirably less than 2.3 mm. It is intended that the tube  34  be sized with an outer diameter that is smaller than the ear canal so that it may be inserted therein comfortably, for example, approximately 2-3 mm and less than 3 mm and desirably less than 2.4 mm. The outer diameter of the tube  34  may be minimized to allow for insertion of the tube  34  into smaller sized ear canals, for example, those of toddlers and infants which may be as small as 3 to 4 mm in diameter. A length of the tube  34  may be approximately 8-12 mm and at least 8 mm to allow the protective sheath  12  to extend past minor obstructions, such as normally present earwax, but allow passage of the held electronic camera  18  proximate the ear drum to allow for imaging of the ear drum of the ear. 
     In certain embodiments, the tube  34  may be cylindrical with a constant inner diameter closely matching the outer diameter of the cylindrical probe  14  for good support, although the tube  34  may also be slightly tapered over this length, for example, tapering toward the narrowed distal speculum tip  11 . 
     The tube  34  is open at the distal speculum tip  11  to allow the held electronic camera  18  to be exposed along the speculum axis  22 . The distal speculum tip  11  may support a probe or a tool, for example, a scoop  31  assisting with the removal of ear wax. The scoop  31  extends from the distal speculum tip  11  along the axis  22 , and is upwardly concave toward the axis  22 . 
     A proximal portion  36  of the protective sheath  12  may take the form of a funnel  37  having a central bore flaring outwardly from the tube  34  and extending to an increasingly flaring integrally molded collar  38  coupling the otoscope  16 . A diameter of a distal end of the funnel  37 , measured in a plane perpendicular to the speculum axis  22 , may be approximately 2-3 mm, and a diameter of a proximal end of the funnel  37 , extending from the distal end of the funnel  37  along the speculum axis  22  by at least 12 mm, may be 9-10 mm. The funnel  37  may be flared outwardly toward the integrally molded collar  38  of the protective sheath  12  at approximately 15-20 degrees from the speculum axis  22  and approximately 18 degrees from the speculum axis  22 . The increased diameter of the funnel  37  compared to the narrow tube  34  may assist in controlling the insertion depth of the speculum  10  such that the proximal portion  36  can only extend partially into the ear canal  21  to prevent the distal tube  34  from extending too deeply into the ear canal  21  which would risk damaging or puncturing the ear drum. 
     The funnel  37  expands outwardly to the increasingly flaring integrally molded collar  38  which is engageable over a head portion  24  of the otoscope  16  to be secured thereon. The collar  38  may take a similar conical shape, flaring outwardly toward the proximal end of the protective sheath  12  at approximately 40-45 degrees from the speculum axis  22  and approximately 45 degrees from the speculum axis  22 , in a non-flexed state, providing a greater diameter bore for receiving the head portion  24  of the otoscope  16 . A diameter of a distal end of the collar  38 , measured in a plane perpendicular to the speculum axis  22 , may be approximately 9-10 mm, and a diameter of a proximal end of the collar  38 , extending from the distal end of the collar  38  along the speculum axis  22  by at least 3 mm, may be 18-19 mm. 
     The proximal portion  36  of the protective sheath  12  may provide flexing segments  40  formed by axial slots  46  extending along speculum axis  22  and separating the proximal portion  36  into cantilevered sections that are flexible outwardly and/or inwardly by a distance of approximately 0.1-0.5 mm, and at least 0.1 mm, away from and/or toward the speculum axis  22  at its proximal rim  13 . The longitudinally extending slots  46  may be approximately 0.5-1 mm wide and at least 0.5 mm wide and may extend through the proximal rim  13  toward the distal portion  34  a length of at least 8 mm, or at least one-third the length of the protective sheath  12 . 
     In one embodiment the collar  38  may include three equally spaced slots  46  positioned approximately 120 degrees apart about the speculum axis  22  of the proximal portion  36  and forming three cantilevered segments  40   a,    40   b,    40   c  supported at a distal end by the protective sheath  12  and detached on left and right sides by the slots  46  and at the proximal rim  13  to allow for outward and/or inward flexure of the segments  40   a,    40   b,    40   c  away from and/or toward the speculum axis  22 . Each of the segments  40   a,    40   b,    40   c  may be independently flexed, however, equal outward/inward forces on segments  40   a,    40   b,    40   c  will generally result in substantially equal outward/inward flexure of each segment  40   a,    40   b,    40   c.    
     An exterior surface  49  of the proximal portion  36  of the protective sheath  12  may support at least one outwardly protruding fin  50  extending from the protective sheath  12 . The at least one outwardly protruding fin  50  may generally span between the funnel  37  and the collar  38  to form a generally triangular tab for finger twisting of the protective sheath  12  by a healthcare professional without the need for additional tools. In one embodiment, the proximal portion  36  may carry three equally spaced fins  50  spaced approximately 120 degrees apart about the speculum axis  22  and generally radially centered between the three equally spaced slots  46  described above. 
     Referring to  FIG. 3 , an interior surface  51  of the proximal portion  36  may support at least one radially inwardly projecting tooth  52  engaging the inserted head portion  24  of the fully installed otoscope  16 . The tooth  52  may take the shape of an oval, oblong or rectangular projection extending from the interior surface  51  toward the speculum axis  22  and having generally rounded outer edges allowing for a sliding or rolling transition of the tooth  52  into and out of a corresponding groove  58  of the otoscope  16 . The tooth  52  may be at least 1 mm in width, 3 mm in length, and 0.1 mm in depth. The tooth  52  may be oriented so that a longest dimension of the tooth  52  extends along a circumference of the protective sheath  12  while the shortest dimension of the tooth  52  extends along the speculum axis  22 . 
     Turning briefly to  FIGS. 5 and 6 , each tooth  52  may have a front face  53  facing toward a distal end of the protective sheath  12  that is substantially perpendicular to the speculum axis  22  (axis  22 ′ running parallel to axis  22 ), as shown, or may also be canted toward the speculum axis  22  as one moves inwardly along the front face  53 , and thus oriented to abut the front wall of the groove  58  to prevent removal of the tooth  52  from the groove  58  in a forward direction. A rear face  54  of the tooth  52  may be substantially perpendicular to the speculum axis  22 , as shown, or may be canted toward the speculum axis  22  as one moves outwardly along the front face  53 , and thus oriented to abut the rear wall of the groove  58  to prevent removal of the tooth  52  from the groove  58  in a rearward direction. Side faces  55 ,  56  of the tooth  52  may be canted away from the speculum axis  22  as one moves inwardly along the front face  53 , as shown, but may also be canted toward the speculum axis  22  as one moves inwardly along the front face  53 , or may be substantially perpendicular to the speculum axis  22 , and thus oriented to assist with moving the tooth  52  up a ramp of the groove  58 . In one embodiment, an interior surface  51  of each section  40   a,    40   b,    40   c  may support a single tooth  52 . The teeth  52  may be generally centered within each section  40   a,    40   b,    40   c,  between the three equally spaced slots  46 , and positioned toward the proximal end of funnel  37 . The teeth  52  may be rotationally aligned with the outwardly extending fins  50 . 
     Referring now to  FIGS. 1 and 4 , the removable speculum  10  may slide over an otoscope  16  generally providing a housing having a head portion  24  held up by a detachable grip portion  72 . The grip portion  72  is sized to be grasped by the hand of a healthcare professional in the manner of a conventional otoscope with the grip portion  72  extending generally upward from the healthcare professional&#39;s hand to the head portion  24 . 
     The head portion  24  of the otoscope  16  may take the shape of a circular cone tapering to a front end defined by a circular tip supporting a frustoconical mounting boss  74 . A distal end  77  of the frustoconical mounting boss  74  of the head portion  24  of the otoscope  16  supports the extension of the cylindrical probe  14  having a proximal end  78  supported by the head portion  24  and distal end or tip  17  that extends along the axis  20  of the ear canal  21 . The cylindrical probe  14  may extend approximately a length of 8-10 mm and at least 8 mm, to allow the front facing electronic camera  18  at the distal probe tip  17  to reach a desired depth within the ear canal  21 . The distal tip  17  of the cylindrical probe  14  supports the electronic camera  18  for viewing into the ear canal  21  and communicating with an electronic display displaying the otoscope image from the electronic camera  18  and is positioned at the distal tip  17  of the cylindrical probe  14  along the axis  20  and centered along the axis  20  as understood in the art. The electronic camera  18  may, for example, be a self-contained charge coupled device (CCD) camera such as is commercially available providing, for example, a measurement area of 1.4 mm diagonal and 62,500 pixels. 
     An outer rim of the frustoconical mounting boss  74  may provide grooves  58  therein and corresponding with the teeth  52  of the removable speculum  10 . The grooves  58  of the otoscope  16  may be generally rectangular holes approximately 1 to 2 mm in width, 3 to 4 mm in length, and 0.1 to 0.5 mm in depth. In one embodiment, the cylindrical mounting boss  74  may support three equally spaced grooves  58  spaced approximately 120 degrees apart about axis  20  whereby a greatest dimension of the rectangle extends along a circumference of the cylindrical mounting boss  74  and a shortest dimension of the rectangle extends along axis  20 . 
     Referring now to  FIG. 5 , the rectangular grooves  58  may provide front and rear substantially perpendicular side walls  80 ,  82  (to axis  20 ′ parallel to axis  20 ), respectively, preventing the teeth  52  from being removed from the grooves  58  in forward and rear directions along the axis  20 . In this manner, the removable speculum  10  cannot be easily removed by the healthcare professional and is secured to the otoscope  16  once installed. 
     Referring now to  FIG. 6 , the rectangular grooves  58  may provide lateral side walls  84 ,  86  whereby at least one of the side walls  84 ,  86  is angled to provide a ramp in which the tooth  52  may slide or ride up the angled side wall  84 ,  86  and become disengaged from the groove  58  when the removable speculum  10  is rotated in at least one of a clockwise or counterclockwise direction. The angulation of at least one of the sidewalls  84 ,  86  may be at least 45 degrees from perpendicular and at least 45 degrees. It is understood that one or both of the lateral side walls  84 ,  86  may be angled to provide an exit ramp for the tooth  52 . In one embodiment, one lateral side wall  84  is angled while the opposite side wall  86  extends substantially perpendicular to the floor of the groove  58 . In this respect, twisting motion in one direction (toward the angled side wall  84 ) will allow for the removal of the removable speculum  10  from the head portion  24  of the otoscope  16  while twisting motion in the opposite direction will be prevented by the substantially perpendicular side wall  86 . In an alternative embodiment, both lateral side walls  84 ,  86  are angled such that twisting in either clockwise or counterclockwise directions will allow for the removal of the removable speculum  10  from the head portion  24  of the otoscope  16 . 
     Referring again to  FIGS. 1, 4 and 5 , the removable speculum  10  may be inserted over the cylindrical probe  16  by sliding the speculum  10  rearward along the insertion axis  20  over the cylindrical probe  16  whereby the central bore of the tube  34  holds the cylindrical probe  14  carrying the front facing electronic camera  18  at its tip  17 . The segments  40   a,    40   b,    40   c  of the removable speculum  10  may flex outward to accommodate the head portion  24  as it is inserted into the speculum  10 . The speculum  10  is inserted along axis  20  until the collar  38  extends over the boss  74  of the removable speculum  10 . The speculum  10  may not need to be rotated if the teeth  52  are aligned with the grooves  58  when inserted along axis  20  but in some cases may need to be slightly rotated (less than a quarter turn) until the teeth  52  align with the grooves  58  and the removable speculum  10  snaps into place. 
     Once installed, the axial position of the distal speculum tip  11  of the removable speculum  10  is set so that the distal tip  17  of the cylindrical probe  14  may terminate before the distal tip  11  of the removable speculum  10 . In one embodiment, the distance between the distal tip  17  of the cylindrical probe  14  and the distal tip  11  of the removable speculum  10  may be approximately 1-2 mm, or less than 2 mm. The distance between the distal tip  17  of the cylindrical probe  14  and the distal tip  11  of the removable speculum  10  may be set to minimize blinding internal reflection and narrowed field of view of the electronic camera  18  while still protecting the fragile electronic camera  18  from contamination and damage. 
     Referring again to  FIG. 6 , an approximately quarter turn twist of the removable speculum  10  slides the tooth  52  along one of the angled side walls  84 ,  86  while the segments  40   a,    40   b,    40   c  of the removable speculum  10  flex outward (at least 0.1 mm) to accommodate the outward movement of the tooth  52 . Once the tooth  52  is displaced from the groove  58 , forward motion of the removable speculum  10  along the axis  20  allows the removable speculum  10  to be detached from the head portion  24  of the otoscope  16 . 
     As is generally understood, the outer ear of a human patient includes a pinna providing a sound collecting structure. The pinna surrounds the ear canal  21  leading to and terminating at the tympanic membrane or eardrum. A length of the ear canal  21  in an average adult human is approximately 25 mm and the ear canal  21  has an average diameter of approximately 7 mm. A length of the ear canal  21  in an average infant is approximately 5 and the ear canal  21  has an average diameter of approximately 3-4 mm. 
     Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
     When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications are hereby incorporated herein by reference in their entireties.