Abstract:
A malleable cannula having multiple lumens, constrained at the proximal end portion to provide rigidity and malleable at the distal end portion. The cannula has a combination of flexibility and stiffness that assists in accessing body passageways without kinking.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a medical cannula used to deliver fluids. 
       BACKGROUND 
       [0002]    Sinusitis is an inflammation of the mucosal tissue lining of the sinus walls which may lead to nasal passageway blockage, mucous stagnation and bacterial or fungal sinus cavity infection. Typical treatments begin with antibiotics. However, when antibiotics cannot relieve sinusitis, sinus surgery (which involves opening the sinus cavities and removing mucosal tissue) may be an alternative. Post-operative care for such surgery requires temporary and uncomfortable sinus packing or gauze which supports the reopened sinus passage and absorbs excess fluid while the tissues heal. After several days or at the discretion of the physician, the gauze packing is removed. Doing so is painful. 
         [0003]    Sinus sealants and other biological materials have emerged as a promising technique to temporarily seal or otherwise protect the post-operative passageways with less intrusion and pain than that caused by traditional packing techniques. 
       SUMMARY OF THE INVENTION 
       [0004]    Biomaterials have been used in ear, nose, and throat (ENT) procedures for surgical repair and drug delivery. The chemical nature of some biomaterials requires that they be provided in a multi-component form with the components being separated prior to use. The components are mixed together shortly before or during delivery, and the mixture rapidly forms a gel or solid. 
         [0005]    There are, however, potential difficulties when using highly-reactive multi-component biomaterial systems. If the components react too rapidly, the resulting mixture may exhibit poor or erratic performance. Rapid reaction may however be desired for other reasons, such as a need for the biomaterial system to be spray-applied yet quickly form a gel or solid at a desired application site. An operator also desirably should be able to dispense the biomaterial using a single gloved hand. 
         [0006]    Other concerns encountered using tissue sealants such as sinus sealants include navigating the sealant delivery system within a patient&#39;s anatomic structures. For example, sealants may be delivered through a cannula having one or more lumens through which fluids can flow. The cannula requires flexibility for insertion through various pathways that may twist and turn, sometimes abruptly at acute angles. At the same time, the cannula should be able to resist kinking or closing off of the lumen and permit uninterrupted fluid flow. 
         [0007]    The invention provides, in one aspect, a multi-sectioned cannula comprising:
       a) a malleable member having a proximal portion and a distal portion;   b) at least one lumen within and extending between the proximal and distal portion; the at least one lumen in fluid communication with a fluid supply; and;   c) a reinforcement member extending along the length of the at least one lumen; the cannula having a durometer such that the cannula does not kink when bent greater than 45 degrees.       
 
         [0011]    The invention provides, in another aspect, a method of dispensing fluids to a target site, the method comprising:
       A) providing a spray delivery system comprising:
           (i) at least one fluid supply; and   (ii) a cannula, the cannula comprising:
               a) a malleable member having a proximal portion and a distal portion;   b) at least one lumen within and extending between the proximal and distal portion; the at least one lumen in fluid communication with a fluid supply; and;   c) a reinforcement member extending along the length of the at least one lumen; the cannula having a durometer such that the cannula does not kink when bent greater than 45 degrees; and   (iii) a spray head through which the at least one fluid supply exits;   
               
           B) dispensing fluid from the fluid supply into the at least one such lumen and through the spray head.       
 
         [0020]    The disclosed apparatus and method have particular use for accessing various anatomical locations such as sinus cavities and for applying tissue sealants at these anatomical locations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0021]      FIG. 1  is a perspective view of a partially assembled spray delivery system including an exemplary cannula; 
           [0022]      FIG. 2  is a perspective, exploded view of the cannula of  FIG. 1 ; 
           [0023]      FIG. 3A  is a perspective view of a shroud and support member; 
           [0024]      FIG. 3B  is a perspective view, partially in cross-section of the  FIG. 3A  shroud; 
           [0025]      FIG. 4A  is a perspective view of a distal portion of the cannula; 
           [0026]      FIG. 4B  is a perspective, exploded view of components in the  FIG. 4A  cannula; 
           [0027]      FIGS. 5A-B  are perspective views, partially in phantom, of the  FIGS. 4A and 4B  cannula. 
       
    
    
       [0028]    Like reference symbols in the various figures of the drawing indicate like elements. The elements in the drawing are not to scale. 
       DETAILED DESCRIPTION 
       [0029]    The recitation of a numerical range using endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). 
         [0030]    The present invention provides, in one aspect, a malleable, kink-resistant cannula and, in other aspects, a method of delivering tissue sealants using such cannula. The cannula can be bent to desirable configurations that are maintained during use and without the cannula or its lumen(s) kinking or closing off and thereby provide uninterrupted fluid delivery through the lumen(s). This kink-resistant feature permits the cannula to be shaped and reshaped during a sealant delivery process while fluid is flowing through the cannula. 
         [0031]    The cannula may be assembled to a delivery system and spray head that may be used to apply multi-component fluid compositions. Such delivery systems and spray heads, for example, include those described in U.S. patent application No. (Attorney Docket Nos. P0041646.USU4 and 151-P-41646US04) and U.S. patent application No. (Attorney Docket Nos. P0041646.USU2 and 151-P-41646US02), respectively, filed even date herewith and each of which is incorporated herein by reference in its entirety. 
         [0032]    The apparatus and method may be used to apply compositions containing multiple agents, such as a multiple component tissue sealant (e.g. two components) to a variety of bodily passageways or cavities including nasal cavities and sinus cavities (e.g. maxillary, frontal or sphenoid sinuses). Exemplary multi-component tissue sealants may include reactive polysaccharides, for example, chitosan and starch. Other exemplary multi-component tissue sealants are provided in U.S. patent application Ser. No. 12/429,141, now published as U.S. Patent Application Publication No. 2009/0270346A1 and U.S. patent application Ser. No. 12/429,150, now published as U.S. Patent Application Publication No. 2009/0291912 A1. 
         [0033]      FIG. 1 , which shows a partially assembled spray delivery system  1 , includes an actuating member  2 , and a body  5  capable of receiving and capturing syringes  4 ,  6 . The actuating member  2  operates upon syringes  4 ,  6  to provide simultaneous delivery of fluids housed in syringes  4 ,  6 . The spray delivery system  1 , as shown in  FIG. 1 , further includes cannula  14  and spray head  20 . 
         [0034]    Cannula  14  may be a flexible or malleable member that may be assembled to include a rigid proximal end portion  16  and a malleable distal end portion  18 . The rigid proximal end portion  16  may be constrained at the proximal end by support shaft  12  and shroud  11 , which prevents or discourages cannula bending. The rigid proximal end portion  16  also includes the portion of cannula  14  surrounded by support shaft  12 . Cannula  14  may be bent at the malleable distal end portion  18 , which extends from the end of the support shaft  12  up to the proximal portion of the spray head  20 . 
         [0035]    Cannula  14  and spray head  20  are connected to body  5  through manifold  10 . Manifold  10  may be surrounded by a shroud  11  with support shaft  12  constraining the proximal end of cannula  14 . Manifold  10  may be configured to receive portions of syringes  4 ,  6  without requiring threaded or rotating engagement of the syringe to manifold  10  to provide a liquid tight connection. Spray head  20  is connected to malleable distal end portion  18 . Covering the interface between the malleable distal end portion  18  and spray head  20  is a sheath  19  which provides a smooth transitional interface at the joint between cannula  14  and spray head  20 . 
         [0036]    When used to deliver a tissue sealant to a sinus cavity, cannula  14  preferably has an overall length of about 10 cm to 15 cm, more preferably about 12 to 13 cm. The rigid proximal end portion  16  may have a length in the range from about 4 cm to 8 cm, preferably about 5 cm to 7 cm, and the malleable distal end portion  18  may have a length, for example, in the range from about 4 cm to 8 cm, preferably about 5 cm to 7 cm. The outer diameter of cannula  14  may be from about 0.1 cm to 1.0 cm, preferably about 0.3 cm to 0.4 cm. The ratio of the rigid proximal end portion  16  to the malleable distal end portion  18  may be in a ratio of about 2:1 or about 1:2, and preferably about 1:1. 
         [0037]    Depending on the specific cannula use, other dimensions are also acceptable. For example, cannula  14  may be used in laparoscopic anatomical or gynecological surgery, neural surgery, pulmonary surgery or the like. 
         [0038]    The cannula  14  may be formed of a material acceptable for use inside the human body and of a selected durometer (hardness). The selected durometer aids in preventing the cannula from kinking when bent greater than 45 degrees, greater than 90 degrees, or greater than 180 degrees with respect to a straight, unbent configuration. The selected material may include for example, thermoplastic or thermoset polymers such as polyolefins, silicones, polyvinyl chlorides, polyurethanes, polyesters and the like. To attain a desired durometer, fillers or plasticizers may be used. The amount and type of filler or plasticizer is determined by the selected thermoplastic or thermoset polymers used. Cannula  14  may have a durometer (Shore A) in the range, for example, from 60 to 95, preferably from about 85 to 95. 
         [0039]    Referring to  FIG. 2 , support member  12  may be in the form of a cylindrical metal or plastic tube surrounding cannula  14  and molded within or otherwise connected to the distal end portion of shroud  11 , for example, by adhesive or welding. The support member  12  preferably is made of stainless steel. Other exemplary materials include, for example, metals such aluminum and plastics such as thermoplastic or thermoset polymers. The support member  12  desirably has a thickness and length such that it minimizes physical obstruction during anatomic insertion and resists sideways deflection of proximal end portion  16  so as to provide improved control when maneuvering and navigating cannula  14  through bodily passageways. The support member  12  may, for example, have a thickness of about 0.01 cm to about 0.1 cm, preferably from about 0.02 cm to 0.03 cm; and a length, for example, of about 3 cm to 10 cm, preferably from about 4.5 cm to 5.5 cm. 
         [0040]    As illustrated in FIGS.  2  and  3 A-B, shroud or casing  11  surrounds outer portions of manifold  10 . The shroud  11  also engages the support member  12 , and when assembled to cannula  14 , provides additional proximal rigidity to the cannula  14 . Shroud  11  may be permanently attached to the manifold  10 , for example, by adhesives, welding or injection molding or may be optionally removable. 
         [0041]    As illustrated in  FIGS. 4A-B , sheath  19  may, for example, surround the proximal portion of spray head  20  and the distal end portion  18  producing a smooth interface between the spray head  20  and cannula  14 . Sheath  19  also helps keep spray head  20  firmly attached to cannula  14  when withdrawing spray head  20  from a confined location. 
         [0042]    Desirable lengths of sheath  19  may for example, range from about 10 mm to 50 mm, preferably from about 20 mm to 25 mm. A thickness for sheath  19  desirably may be selected such that it minimizes interference with anatomical features during cannula insertion. The sheath thickness may, for example, range from to 0.001 cm to 0.010 cm, preferably 0.001 cm to 0.003 cm. The sheath  19  may be a heat shrink tube, a mechanically expanded tube, or an extruded plastic tube, and may be made from a variety of materials, for example, polyester, polyolefin, and fluoropolymers. 
         [0043]    As shown in  FIGS. 5A-B , an exemplary cannula  14  may enclose multiple lumens that extend the entire cannula length, from the rigid proximal end portion  16  to the malleable distal end portion  18  and maintains the separation of each lumen. The individual lumen diameters are dependent on a number of factors, including the spray head opening diameters, the desired pressure and flow rate. The lumens may, for example, all be of the same diameter and cross sectional shape. The lumen shape may be, for example, circular, oval, square or D-shaped in cross-section, with the flat portions of neighboring D-shapes being adjacent to one another. 
         [0044]    As illustrated in  FIG. 5A , at least one of the lumens may include a reinforcement member  22  to allow selective bending of the cannula  14  to fit different orientations. The reinforcement member  22  may, for example, be in the form of a wire located within and extending along the length of a lumen. The reinforcement member  22  may, but need not be centrally located in the multi-lumen cannula  14 . In such embodiments, the cannula  14  may be formed with at least two lumens, one of which will become occupied by the reinforcement member  22 . The cannula  14  may also be formed by extruding or molding it over the reinforcement member  22  and by providing at least one lumen through which fluid may flow. 
         [0045]    The reinforcement member  22  may be made of, for example, metal or a metal alloy such as stainless steel, copper, aluminum or the like. In other examples, reinforcement member  22  may be made of a shape memory metal such as Nitinol. The diameter of the reinforcement member  22 , may, for example, range from 0.001 cm to 0.10 cm, preferably 0.03 cm to 0.05 cm. The shape of the reinforcement member  22  may be, for example, circular, oval, square or D-shaped in cross-section. The stiffness of the reinforcement member  22  may be full hard, half hard, quarter hard, annealed, soft or any other desired stiffness depending on the desired application. 
         [0046]    The cannula  14 , illustrated in  FIGS. 5A-B , includes four lumens, one of which is occupied by reinforcement member  22 . Remaining lumens  24 ,  26 ,  28  are in fluid communication with one or more fluid supplies such as syringes  4 ,  6  and a source of pressurized air (not shown) that may be introduced into lumen  28  via port  30 , which is shown in  FIG. 2 . 
         [0047]    In one exemplary assembly process for the disclosed device, an operator first inserts the actuating member  2  into body  5 . Alternatively, actuating member  2  may be preassembled with body  5 . Syringes  4 ,  6  are positioned against body  5  and actuating member  2  so that body  5  and actuating member  2  can receive and capture syringes  4 ,  6 . In this manner, syringes  4 ,  6  are held substantially parallel in body  5 . 
         [0048]    Once the syringes are received and captured by body  5 , cannula  14  and spray head  20  are assembled to body  5  through manifold  10 . Cannula  14  and spray head  20  may if desired be preassembled to manifold  10  during manufacturing. 
         [0049]    The operator then connects manifold  10  to syringe outlets to provide an unthreaded, liquid-tight connection such that the syringe contents in syringe barrels are in fluid communication with cannula  14  through manifold  10 . 
         [0050]    When the delivery device  1  is fully assembled, the operator shapes the cannula  14  to a desired shape. Cannula  14  desirably is sufficiently stiff so that it will retain its shape until bent into a new shape. The shaped cannula  14  and spray head  20  are then maneuvered or navigated into a desired treatment site within the patient&#39;s body, for example, a nasal or sinus cavity or other opening, recess or passageway. Once satisfactorily positioned, an operator may, for example, depress actuating member  2  to move the plunger of syringe  4 ,  6  toward the syringe outlets, advancing the fluid syringe contents substantially at the same time through the separate syringe barrels and out into respective fluid channels in manifold  10  which maintain the fluid separation. Continued force will advance the fluids through the multi-lumen cannula  14  and into a region within spray head  20  where they mix before the mixed fluids exit spray head  20 . If compressed gas is used, it may be supplied through a gas inlet (not shown). The gas stream passes through a lumen of multi-lumen cannula  14  into the mixing region of spray head  20 . The gas stream helps atomize the mixed syringe contents resulting in much smaller droplets. Overall, a smoother manipulation and easier control of the device through passageways is provided. 
         [0051]    The invention is further illustrated in the following non-limiting examples. 
       Example 1 
       [0052]    Delivery device  1  was clamped into a suitable fixture and evaluated using an air flow rate meter to determine rate of air flow through cannula  14  at different user configurations. The air flow rate was measured at least 14 times for each user configuration. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                   
                 Average Air 
                   
               
               
                   
                 Flow Rate 
               
               
                 Test 
                 (L/min) 
                 STDEV 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Air Flow Rate (Straight Cannula) 
                 10.02 
                 0.47 
               
               
                 Air Flow Rate (90° Bent Cannula) 
                 10.05 
                 0.43 
               
               
                 Air Flow Rate (180° Bent cannula) 
                 10.29 
                 0.88 
               
               
                 Air Flow Rate (Greater than 180° Bent Cannula 
                 9.89 
                 0.30 
               
               
                   
               
             
          
         
       
     
       Example 2 
       [0053]    Delivery device  1  was clamped into a suitable fixture and evaluated using a calibrated force gauge to determine the force in Lbf units to bend the cannula 90 degrees. The required force was measured at least 14 times with the cannula bent at 90 degrees. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Test 
                 Average (Lbf) 
                 STDEV 
               
               
                   
                   
               
             
             
               
                   
                 Cannula Bend Force (90°) 
                 1.53 
                 0.11