Abstract:
A middle ear fluid aspirator comprised of a syringe assembly that provides suction through the creation of negative pressure therein and a needle having an angled region that permits the operation of the aspirator while maintaining visual contact with the tympanic membrane and a needle safety assembly whereby the penetrating portion of the needle is not capable of damaging the ossicular structures of the ear.

Description:
PRIORITY CLAIM 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/207,695, now U.S. Pat. No. 6,024,726 filed on Dec. 8, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to aspirators, and, in particular, to aspirators for removing fluid from the middle ear. 
     BACKGROUND OF THE INVENTION 
     Infections of the middle ear present an ongoing problem to both patients who suffer from them as well as to treating physicians who seek to treat them. To the patient, these infections represent acute pain, discomfort, financial cost and/or possible loss of hearing. To the treating physician, these infections present significant dilemmas. Since middle ear infections have been heretofore difficult to treat with medications, the treating physician had basically two therapeutic alternatives. 
     The primary care physician may either tap the middle ear or refer the patient to an ear, nose and throat specialist so that a tympanocentesis or insertion of tubes may be employed. In order to the tap the middle ear, the physician has utilized suction or conventional syringes which have several attendant disadvantages. Suction assemblies are often not available and are cumbersome to use. Conventional syringes have required the physician to actuate the syringe by pulling back on the plunger. Further, if the needle of the syringe is straight, as is usually the case, then the syringe interferes with the operator&#39;s line of vision. A common danger with pre-existing syringe needles is that there is no guard against the operator accidentally penetrating the tympanic membrane in such a way as to cause damage to the bony structures there within. 
     Therefore, there is a need for an aspirator with increased control that allows a clear line of sight with the tympanic membrane and includes safety features which prevents damage to the ear canal and middle ear structures. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, a present invention is a middle ear fluid aspirator comprising a syringe assembly and needle. The syringe assembly operates via negative pressure in order to provide suction through the needle when the syringe handle is pushed. The needle has an angled or curved region, which permits the operator to use the aspirator while having visual contact with the tympanic membrane. The needle has a fibrillar sheath that shields the sharp tip of the needle to prevent injury while entering the ear canal and retracts upon contact with the tympanic membrane. The sheath may also act as a carrier for anesthetic. A stop is also positioned on the needle to restrict movement of the sheath, thereby helping to limit penetration of the needle. The tip of the needle preferably has a shallow bevel to prevent lateral contact with the medial wall of the middle ear. Preferably, the needle has thin walls that deform when it contacts bone. 
     A syringe assembly that is actuated by pushing on the handle is a major advantage of present invention. With a physician being able to push the syringe handle rather than pull, the aspirator can be operated with a single hand with greater control with a single hand since the muscles that control the hand can squeeze the thumb toward the rest of the hand more easily than pull it away from the hand. 
     An important advantage of the present invention is ability to have a clear line of sight with the tympanic membrane. In accordance with this advantage, the needle has a curved portion so that the syringe handle does not obstruct the view of the tip of the syringe. Moreover, the amount of suction delivered to the needle tip is proportional with the rate at which the plunger is pressed. 
     A major feature of the present invention is the sheath that shields the needle tip until contact with the tympanic membrane. The sheath creates a safety advantage by preventing injury to the ear canal when introducing the needle into the ear. A secondary feature of the sheath is its use as a carrier for anesthetic, or other fluid to be applied to the tympanic membrane. As a result of the carrier function, the fluid can be applied to the tympanic membrane in one step, without the need to introduce another instrument into the ear. Moreover, the sheath acts as a seal around the puncture site while permitting the withdrawal of fluid through the needle to prevent aspiration of air from the ear canal instead of fluid from the middle ear. 
     An important feature of the present invention is a stop that acts in conjunction with the sheath to limit penetration of the needle. As a result, the physician can be assured that the needle will be prevented from penetrating too far and damaging middle ear structures. 
     The shallow bevel of the needle tip is another feature of the present invention. Since the middle ear is a shallow structure, the shallow bevel allows sufficient penetration of the needle to allow aspiration of fluid while preventing aspiration of air from the ear canal. 
     Other features and advantages of the present invention will be apparent to those skilled in the art from a careful reading of the Detailed Description of a Preferred Embodiment presented below and accompanied by the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the middle ear fluid aspirator inserted through the tympanic membrane of a patient, according to a preferred embodiment of the present invention; 
     FIG. 2 is an exploded cross-sectional view middle ear fluid aspirator, according to a preferred embodiment of the present invention; 
     FIG. 3 is a cross-sectional view of the syringe assembly of the middle ear aspirator of the present invention along the  3 — 3  line of FIG. 2, according to a preferred embodiment of the present invention; 
     FIG. 4 is a cross-sectional view of the needle carrying a sheath along line  4 — 4  of FIG. 5A, according to a preferred embodiment of the present invention; 
     FIG. 5A is a cross-sectional view of the needle carrying a sheath prior to penetration of the tympanic membrane, according to a preferred embodiment of the present invention; and 
     FIG. 5B is a cross-sectional view of the needle carrying a sheath upon penetration of the tympanic membrane, according to a preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, the syringe assembly of the present invention is identified by the numeral  1  and is shown in place within the ear canal  47  of a patient. The tip  43  of the syringe needle  42  is shown penetrating the tympanic membrane  50  so that fluid accumulated within the middle ear may be extracted by use of syringe  1 . Needle  42  draws fluid from the middle ear into a second compartment  30  of housing  10  when tip  43  penetrates tympanic membrane  50  and a handle  28  is pressed with the user&#39;s thumb, driving shaft  26  into housing  10 . 
     With reference to FIG. 2, syringe assembly  1  is comprised of a housing  10 , a partition  14 , dividing the housing  10  into a first compartment  18  and a second compartment  30 , an opening  16  allowing first compartment  18  to communicate with second compartment  30 , a piston  24 , disposed in first compartment  18  and attached to shaft  26 , a first end wall  48  having a port  49  that is disposed at the end of first compartment  18 , a seal means  22 , a slide stop  20 , and a needle hub  32  carried on second compartment  30 . 
     The housing  10  generally cylindrical in shape and may be made of any suitable, and preferably translucent, material such as glass, plastic, or the like. Housing  10  is divided into a first compartment  18  and second compartment  30  by partition  14 . First end wall  48  has a port  49  for the egress of air when handle  28  is pressed, and a second end wall  31  and seal means  22  which may be a natural or synthetic rubber or plastic ring. First compartment  18  is connected to second compartment  30  by opening  16 . Disposed within first compartment  18  is piston  24  which is attached to shaft  26 . Shaft  26  extends through seal means  22  and through aperture  27  and is attached to handle  28 . As the operator applies pressure to handle  28 , shaft  26  forces piston  24  to move from an initial position adjacent to and in contact with slide stop  20  towards end wall  48 . Such movement causes negative pressure behind piston  24  and thereby causes fluid flow into second compartment  30  through opening  16 . Piston  24  and seal means  22  are made of any suitable material which is inert to the aspirated fluid and provides a sufficiently airtight seal with the walls of first compartment  18  and slidable seal with shaft  26  such that piston  24  can be moved in and out of housing  10  and create sufficient negative pressure inside first compartment  18  to aspirate fluid into second compartment  30 . 
     Needle hub  32  provides a location for frictionally fitting needle anchoring means  34  such that needle  42  may be attached to syringe assembly  1  at needle hub  32  in an airtight fashion in which the lumen  54  of needle  42  is in fluid communication with second compartment  30  for flow of fluids from lumen  54  through aperture  27  into second compartment  30 . Needle  42  is provided with angled or curved region  38  allowing insertion of needle  42  into ear canal  49  of a patient while allowing the user visual access to the tympanic membrane  50  while sighting along needle  42  towards its tip  43  while holding handle  28  to the side where it is not in the line of sight. Angled region  38  is bent to a suitable degree for use with an otoscope, and may range from about 60° to about 30°, preferably about 45°. 
     With reference to FIG. 3, a cross-sectional view of syringe assembly  1  along axis  3  wherein first compartment  18  is shown in relationship to second compartment  30  within housing  10 . In first compartment  18  slide stop  20  can be seen. Extending therethrough is shaft  26  which is anchored to piston  24 . 
     As best seen in FIG. 5A, needle  36  has a shallow bevel  51 , which prevents aspiration of air from ear canal  47  but allows easy penetration of the tympanic membrane for aspiration of fluid from the middle ear. By the term shallow, it is meant that the bevel angle, represented by θ, is more than a few degrees and preferably approximately 45°. The needle tip  43  has a second bevel, a counter-bevel portion  52 , which provides a sharp tip  43  to enable easy penetration of the tympanic membrane  50 . Preferably only the needle tip  43  has a counter-bevel portion  52 , rather than the entire bevel  51 . As a result, the counter-bevel portion  52  allows for initial penetration, but the remaining bevel  51  acts to stretch the tympanic membrane  50 , rather than cut tissues. 
     Needle tip  43  carries a sheath  68  primarily to prevent injury to the ear canal  47  when the needle  42  is introduced into the ear. Sheath  68  is preferably made from a fibrillar or foamy material, such as that sold under the trademarks Gel Foam or Dacron, would be suitable material for sheath  68 . Sheath  68  shields ear canal from injury during introduction into ear as seen in FIG. 5A; however, upon sheath  68  contact with tympanic membrane  50 , sheath  68  moves axially from a first, needle tip-covering position to a second, needle tip exposing position to allow penetration as seen in FIG.  5 B. Stop  70 , which defines the second position, restricts axial movement of sheath  68  and thereby helps to prevent excessive penetration of tip  43 , as illustrated in FIG.  5 B. Stop  70  is positioned along needle  42  to allow retraction of sheath  68  while limiting penetration of needle  42 . A secondary function of sheath  68  is a use as a carrier for delivering a material to the tympanic membrane  50 , such as an anesthetic and/or antiseptic solution (not shown). 
     In use, needle  42  is inserted into ear canal  47  with sheath  68  carried on it to shield needle tip  43  to prevent injury to the ear canal  47 . Upon sheath  68  contact with the tympanic membrane  50 , sheath  68  slides axially by pressure of the tympanic membrane to stop  70 , to allow exposure and penetration of needle tip  43  into tympanic membrane  50 . The physician or user pushes handle  28  toward needle  42  to aspirate fluid from the middle ear. 
     While the present invention has been described with respect to embodiments, it will be understood that various modifications and variations will occur to those skilled in the art from the foregoing detailed description and the accompanying drawings. Such modifications and variations are intended to fall within the scope of the appended claims.