Patent Publication Number: US-2007113855-A1

Title: Respiratory apparatus with improved seal

Description:
BACKGROUND  
      A variety of different circumstances exist in which a person may be required to have an artificial airway, such as an endotracheal tube, placed in their respiratory system. During surgery, for instance, the artificial airway functions to keep the patient&#39;s airway open so that adequate lung ventilation is maintained during the surgical procedure. Alternatively, with many patients the endotracheal tube will remain in place to sustain mechanical ventilation for a prolonged period.  
      If an endotracheal tube is to be left in place for any substantial amount of time, it is critical that respiratory secretions be periodically removed. This is usually accomplished with the use of a respiratory suction catheter. As the suction catheter is withdrawn, a negative pressure may be applied to the interior of the catheter to draw mucus and other secretions from the respiratory system.  
      With conventional closed suction catheter assemblies, the catheter tube is enveloped by a protective sleeve. The catheter assembly includes a valve mechanism in communication with a vacuum source to control the suctioning process. At its distal patient end, the closed suction catheter assembly is attached to a manifold, connector, adaptor, or the like.  
      After the application of negative pressure, the catheter tube may be withdrawn from the artificial airway and, as the catheter tube is pulled back into the protective sleeve, a resilient wiper or seal within the distal end manifold strips or scrapes a substantial portion of any mucus or secretions from the outside of the catheter tube. The seal also prevents the patient&#39;s ventilation air from escaping from around the suction catheter.  
      The current seal design is a flat, washer-shaped disc with the inner diameter of the disc generating a sliding friction fit with the catheter. This friction fit must be sufficient to ensure a proper wiping action upon withdrawal of the catheter as well as prevent the escape of ventilation air and, in this regard, a relatively tight fit is necessary between the catheter and the seal. This requirement often results in difficulty in sliding the catheter through the seal, particularly for insertion into the patient&#39;s airway, and may result in stenosis or necking-down of the catheter diameter. Moreover, this configuration provides little tolerance for catheter diameter variances.  
      Thus, a need exists in the art for an improved wiper or seal in a respiratory suction apparatus that addresses these drawbacks with conventional seal designs.  
     SUMMARY  
      Various objects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned from practice of the invention.  
      A respiratory apparatus according to the invention includes a suction catheter having a tubular portion with a lumen defined therethrough. The suction catheter is adapted for removing fluids from a patient by insertion of the tubular portion into a patient&#39;s artificial airway with subsequent application of negative pressure to the proximal end of the lumen. A manifold is configured in communication with the patient&#39;s artificial airway and includes a port through which the suction catheter is advanced and withdrawn from the patient&#39;s artificial airway.  
      A resilient material seal is disposed within the manifold port and includes an aperture through which the suction catheter passes. This seal provides a sliding frictional sealing fit with the suction catheter and serves to wipe or scrape respiratory secretions from the outer surface of the suction catheter as the catheter is withdrawn from the patient&#39;s airway.  
      In accordance with certain aspects of the invention, the wiper seal has a unique configuration that provides the seal with distinct advantages. In a particular embodiment, the seal includes a radially outer flange section and an inner conically shaped skirt section defining the aperture through which the suction catheter passes. A bridge section is provided between the outer flange section and the conical skirt section. The outer flange section defines an inner diameter with the bridge section extending radially inward from this inner diameter at a first angle relative to the outer flange section. The conical skirt section extends radially inward from the bridge section at a second angle relative to the bridge section that is less than the first angle between the bridge section and the outer flange. A seal lip is configured at the end of the conical skirt section to engage against the outer surface of the suction catheter.  
      The angled configuration between the various sections of the seal, selection of material, and relative thickness of the sections all contribute to provide the seal with unique characteristics. For instance, when the suction catheter is slid through the seal as the catheter is advanced into the patient&#39;s airway, frictional resistance between the conical skirt section (the sealing lip in particular) is reduced as compared to conventional washer-type seals without sacrificing seal effectiveness. Resistive forces are directed longitudinally along the length of the skirt section such that the skirt section tends to stretch along this axis. Also, the angle between the skirt section and bridge section defines a flex point between the sections that allows the skirt section to flex radially outward towards the outer flange section. A flex point is also defined between the bridge section and outer flange section. These features allow the seal to effectively accommodate a wider range of suction catheter diameters as compared to conventional seal designs.  
      In a particular embodiment, the outer flange section has a radial thickness greater than a thickness of the conical skirt section. The outer flange section may also have a radial thickness greater than the thickness of the bridge section. This configuration may be desired to enhance the flex action between the bridge section and outer flange section. In an alternate embodiment, the bridge section and conical skirt section may have generally about the same thickness.  
      In a particularly unique embodiment, the outer flange section has a radial thickness greater than the thickness of the conical skirt section and the bridge section, and the bridge section has a thickness greater than the thickness of the conical skirt section.  
      The first angle between the bridge section and the outer flange section may vary. For example, in one embodiment this angle may be about 90 degrees such that the bridge section extends essentially perpendicular to the flange section. In an alternate embodiment the first angle may be greater than 90 degrees.  
      The second angle between the bridge section and the conical skirt section may also vary, and may be a function of the first angle between the bridge section and flange section. For example, the second angle will generally greater than 90 degrees when the first angle is 90 degrees or less. If the first angle is greater than 90 degrees, the second angle will generally be 90 degrees or less.  
      Although not a requirement, the bridge section may be defined at a longitudinal end of the outer flange section. In an alternative embodiment, the outer flange section may extend longitudinally on either side of the bridge section.  
      The seal may be made of various known resilient seal materials, with all of the seal sections being integrally formed into a single seal component.  
      The seal lip may have various configurations, and may be directly formed with the conical skirt section or subsequently defined at the end of the skirt section.  
      In a particular embodiment, the seal lip is a relatively sharp point edge defined by angled planar surfaces at the end of the conical skirt section. This configuration provides a point knife-edge engagement against the catheter surface. In an alternate embodiment, the seal lip is a planar surface configured to engage the catheter along a longitudinally extending plane. In still another embodiment, the seal lip may be provided with a rounded edge.  
      Aspects of the invention will be described in greater detail below by reference to particular embodiments illustrated in the figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a respiratory apparatus that may incorporate a seal in accordance with the invention.  
       FIG. 2  is a cross-sectional view of the manifold section of the respiratory apparatus that incorporates a seal in accordance with the invention.  
       FIG. 3A  is cross-sectional view of the seal position and orientation within the manifold prior to insertion of suction catheter through the seal.  
       FIG. 3B  is a cross-sectional view of the seal in  FIG. 3A  after insertion of the suction catheter through the seal.  
       FIG. 4  is a cross-sectional view of an alternate embodiment of a seal configuration in accordance with the invention.  
       FIG. 5A  is a cross-sectional view of another alternate embodiment of a seal configuration in accordance with the invention.  
       FIG. 5B  is a cross-sectional view of still another embodiment of the seal configuration in accordance with the invention. 
    
    
     DETAILED DESCRIPTION  
      Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.  
      As used herein, “proximal” refers generally to the direction towards a medical caregiver. “Distal” refers generally to the direction towards a patient.  
      The present invention relates to a respiratory apparatus that connects to a patient&#39;s artificial airway for a variety of purposes. Referring to  FIG. 1 , an embodiment of the respiratory apparatus  10  is depicted generally as it would be connected to the artificial airway  34  of a patient  18 . The apparatus  10  includes a suction catheter  12  and related components. A ventilator  76  may be in communication with the artificial airway  34  through a swiveling port  64  ( FIG. 2 ) of a manifold  110 . The manifold  110  includes swiveling port  62  ( FIG. 2 ) for connection to the airway  34 . The ventilator  76  may provide air to and remove air from the lungs of the patient  18  through the artificial airway  34 .  
      It is to be understood that the configuration of the manifold  110  shown in  FIGS. 1 and 2  is only an exemplary embodiment of the present invention, and the present invention is not limited to such a manifold. The respiratory apparatus  10  in accordance with the present invention may be provided with manifolds  110  of any configuration known in the art.  
      If the artificial airway  34  is left in the patient  18  for any substantial amount of time, respiratory secretions may build up in the lungs of the patient  18 . As such, these secretions should be removed in order to ensure that adequate lung ventilation of the patient  18  is maintained. These secretions may be removed through use of the suction catheter  12 . The suction catheter  12  has a tubular portion  14  having a distal end  16  with a distal opening  82  therein and a side opening  84  ( FIG. 2 ) that may be extended through the artificial airway  34  into the lungs of the patient  18 . A vacuum source  78  may be in communication with the ventilating circuit, and more specifically in communication with the suction catheter  12 . A medical caregiver actuates a suction valve  74  to apply vacuum pressure to the tubular portion  14  of the suction catheter  12 . Upon doing so, respiratory secretions in the patient  18  and in the artificial airway  34  may be removed.  
      Respiratory secretions may sometimes remain on the tubular portion  14  of the suction catheter  12  or transfer onto other portions of the ventilator circuit. These respiratory secretions are undesirable in that they provide a breeding ground for pathogens and other harmful agents that may harm the patient  18 . It is therefore the case that the suction catheter  12  and/or other components of the ventilation circuit may be cleaned in order to remove any residual respiratory secretions. In order to ensure a lower risk of contamination to the patient  18 , it is common practice to remove and replace the suction catheter  12  after some amount of set time has passed, for instance after 24 or 72 hours of use.  
      As may be seen in  FIG. 2 , the suction catheter  12  is shown with a flexible plastic sleeve  44 . The sleeve  44  may be present in order to contain and isolate respiratory secretions that accumulate on the tubular portion  14  of the suction catheter  12  as the tubular portion  14  is withdrawn from the ventilation circuit.  
      The sleeve  44  may be provided on either end with sealing connections  45  and  47  that attach the sleeve  44  to the suction catheter  12 .  
      The manifold  110  may be permanently attached to the suction catheter  12  and detachable from the artificial airway  34  so that a new suction catheter  12  may be incorporated into the ventilation circuit. In an alternate embodiment, the suction catheter  12  may be removably attached to the manifold  110 , which remains attached to the artificial airway. This embodiment is described in detail in co-pending and commonly owned U.S. application Ser. No. 10/430813 filed on May 6, 2003 incorporated herein by reference for all purposes.  
      The respiratory apparatus  10  includes an instrument introduction section  22  having a passageway extending therethrough. The tubular portion  14  of the suction catheter  12  is advanced through this passageway, through an opening  98  and into the manifold  110 , and eventually advanced into the artificial airway  34  ( FIG. 1 ). Upon retraction of the tubular portion  14  from the patient  18 , respiratory secretions may be present on the surface of the tubular portion  14 . At least one wiper seal  36  may be provided in the instrument introduction section  22 .  FIG. 2  depicts an upper and a lower wiper seal  36 , the lower wiper seal  36  may be provided on some suction catheters, but is in addition to the upper wiper seal  36 .  
      Various embodiments of the wiper seal  36  in accordance with aspects of the invention will be described in detail below. In general, the wiper seal  36  is a resilient member having an aperture through which the tubular portion  14  passes. The wiper seal  36  frictionally engages the tubular portion  14  as the tubular portion  14  is retracted from the artificial airway  34  to a position proximal from the wiper seal  36 . Respiratory secretions present on the surface of the tubular portion  14  are removed by the sliding frictional engagement between the wiper seal  36  and tubular portion  14 .  
      Referring to  FIG. 2 , the instrument introduction section  22  may also be provided with a cleaning section  38 . In one exemplary embodiment, the cleaning section  38  may be defined by a cleaning section member  86 . Additionally or alternatively, the cleaning section  38  may be defined on one end by the upper surface of a valve  32  and the lower surface of the upper wiper seal  36  located proximal to the sealing connection  45 . The valve  32  is shown in a closed position in  FIG. 2  as a single flap that is hingedly attached to an annular ring  31  housed within the instrument introduction attachment section  22 . The hinge on the valve  32  may provide both a bias force and a pivoting location. The valve  32  may be opened by insertion of the tubular portion  14  through the instrument introduction section  22 . A projection  88  on the valve is configured to minimize contact of the valve with the surface of the tubular portion  14 . The valve  32  may include an aperture  42  that helps to establish a more desirable turbulent fluid flow with the cleaning section  38 . Use of such a valve  32  is disclosed in U.S. Pat. 6,227,200 B1issued to Crump et al., the entire disclosure of which is incorporated by reference herein in its entirety for all purposes.  
      The tubular portion  14  of the suction catheter  12  may be cleaned by positioning the distal end  16  of the suction catheter  12  proximal to wiper seal  36 . Upon so positioning, a vacuum may be drawn through the suction catheter  12  and lavage or other cleaning solution may be injected into the cleaning section  38 . Application of vacuum may cause the valve  32  to be forced against the distal side of cleaning section member  86  and form the distal end of cleaning section  38 . However, in other exemplary embodiments, the valve  32  may be biased with enough force to close and seal against the distal side of cleaning section member  86  without application of suction force. However, it is to be understood that injection of lavage or other cleaning solutions and/or application of a vacuum may be performed in instances not associated with cleaning of the tubular portion  14  of the suction catheter  12 .  
      An irrigation port  40  may be provided with the instrument introduction section  22  in order to allow for the injection of the lavage solution. A container (not shown) holding the lavage solution may have an outlet inserted into the irrigation port  40 . Lavage may then be dispensed from this container into the irrigation port  40  which may be in communication with the cleaning section  38 . The irrigation port  40  may also be provided with an irrigation cap  70  that may be connected to the irrigation port  40  by way of a tether  72 . The irrigation cap  70  may be placed onto the irrigation port  40  in order to close the irrigation port  40  when not in use.  
      In certain exemplary embodiments of the present invention, the cleaning section member  86  may be configured such that a small amount of space is present between the tubular portion  14  of the suction catheter  12  and the cleaning section member  86 . In certain exemplary embodiments of the present invention, this space may be between about 0.005 and about 0.015 inches. This space provides two advantages. First, if lavage is needed to be provided to the patient  18 , injection of lavage through the irrigation port  40  and then into the cleaning section  38  causes a stream of lavage solution to be directed out of the manifold  110  and into the patient  18 . Second, as the tubular portion  14  is withdrawn, the close proximity between the tubular portion  14  and the cleaning section member  86  may help to wipe any heavy layers of respiratory secretions from the outside of the tubular portion  14  of the suction catheter  12 .  
      As shown in  FIG. 2 , the instrument introduction section  22  is in axial alignment with the swiveling port  62  that may be further attached to the artificial airway  34  ( FIG. 1 ). This alignment may help to reduce contamination due to the fact that the suction catheter  12  during withdrawal from the patient  18  ( FIG. 1 ) does not have to pass around bends or over other objects in order to be withdrawn into the instrument introduction section  22  proximate to the valve  32 . In effect, this arrangement is a “straight shot” that reduces the chances of respiratory secretions being scraped off of the tubular portion  14  of the suction catheter  12  and being deposited onto a bend or other obstacle in the respiratory apparatus  10 .  
      Turning now to  FIGS. 3A and 3B , some constructions of the seal  36  are depicted. As shown, the seal  36  is disposed within the port between the manifold  110  and the instrument introduction section  22 . In one possible embodiment, the seal  36  includes a radially outer flange section  360  and an inner conically shaped skirt section  362  defining an aperture  364  through which the suction catheter  12  passes. A bridge section  366  is provided between the outer flange section  360  and the conical skirt section  362 . The outer flange section  360  defines an inner diameter  368  with the bridge section  366  extending radially inward from this inner diameter  368  at a first angle relative to the outer flange section  360 . The conical skirt section  362  extends radially inward from the bridge section  366  at a second angle relative to the bridge section that is less than the first angle between the bridge section and the outer flange  360 . A seal lip  370  is configured at the end of the conical skirt section  362  to engage against the outer surface of the suction catheter.  
      In accordance with certain aspects of the invention, the wiper seal  36  has a unique configuration which provides it with distinct advantages. These features include an angled configuration between the various sections of the seal  36 , the selection of material, and the relative thickness of each of the sections  360 ,  362 , and  366 . All contribute to provide the seal with unique characteristics. For instance, when the suction catheter  12  is slid through the seal  36  as the catheter is advanced into the patient&#39;s airway as shown in  FIG. 3B , frictional resistance between the conical skirt section  362  (the sealing lip  370  in particular) is reduced as compared to conventional washer-type seals. This is accomplished without sacrificing seal effectiveness. Resistive forces are directed longitudinally along the length of the skirt section  362  such that the skirt section tends to stretch along this axis. Also, the angle between the skirt section  362  and bridge section  366  defines a flex point between the sections that allows the skirt section  362  to flex radially outward towards the outer flange section  360 . A flex point is also defined between the bridge section  366  and the outer flange section  362 . Of course these areas of flexibility are described as flex points when referring to any particular line through the seal as viewed in the Figs. However, since the seal is annular, the flex points or flex regions should be understood to exist around the entire circumference of the skirt section  362  as well as the entire circumference of the bridge section  366 . The combination of all of these features allows the seal  36  to effectively accommodate a wider range of suction catheter diameters as compared to conventional seal designs.  
      In a particular embodiment, the outer flange section  360  has a radial thickness greater than a thickness of the conical skirt section  362 . The outer flange section  360  may also have a radial thickness greater than the thickness of the bridge section  366 . This configuration may be desired to enhance the flex action between the bridge section  366  and the outer flange section  362 . In one such embodiment, as depicted in  FIGS. 3A and 3B , the bridge section  366  and the conical skirt section  362  may have generally about the same thickness.  
      In another particularly unique embodiment, the outer flange section  360  may have a radial thickness greater than the thickness of the conical skirt section  362  and the bridge section  366 . One such embodiment, shown in  FIG. 4 , may provide that the bridge section  366  has a thickness greater than the thickness of the conical skirt section  362 .  
      In any of the aforementioned embodiments, the first angle between the bridge section  366  and the outer flange section  360  may vary. For example, in some embodiments, this angle may be about 90 degrees such that the bridge section  366  extends essentially perpendicular to the flange section  360 . In alternate embodiments, the first angle may be greater than 90 degrees. The second angle between the bridge section  366  and the conical skirt section  362  may also vary, and may be a function of the first angle between the bridge section  366  and the outer flange section  360 . For example, the second angle will generally be greater than 90 degrees when the first angle is 90 degrees or less, in some instances ranging from about 90 degrees to about 160 degrees. In other embodiments, the second angle may range from about 120 degrees to about 160 degrees. Alternatively, if the first angle is greater than 90 degrees, the second angle will generally be 90 degrees or less.  
      Although not a requirement, the bridge section  366  may be defined at a longitudinal end of the outer flange section  360  as shown in the Figs. However, in alternative embodiments, the outer flange section  360  may extend longitudinally above, below, or on each side of the bridge section  366 .  
      The seal  36  may be made of various known resilient seal materials, with all of the seal sections  360 ,  362 , and  366  being integrally formed into a single seal component  36 . Alternatively, the seal sections  360 ,  362 , and  366  may each be made of dissimilar materials joined by an adhesive or other method known to those of skill in the art. The seal lip  370  may also have various configurations, and may be directly formed with the conical skirt section  362  or subsequently defined at the end of the skirt section  362 . In a particular embodiment, as shown in  FIG. 4 , the seal lip  370  may be a relatively sharp point edge  372  defined by angled planar surfaces  374  and  376  at the end of the conical skirt section  362 . This configuration provides a point knife-edge engagement against the catheter surface. In an alternate embodiment, as shown in  FIG. 5A , the seal lip is a planar surface  378  configured to engage the catheter  12  along a longitudinally extending plane. In still another embodiment, as shown in  FIG. 5B , the seal lip  370  has a rounded edge  380 .  
      It should be understood that the present invention includes various modifications that may be made to the embodiments of the respiratory apparatus described herein as come within the scope of the appended claims and their equivalents.