Patent Publication Number: US-2015059758-A1

Title: Selectable exhaust port assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/615,600, filed on Mar. 26, 2012, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the control of flow patterns of fluids, such as gases, and, more particularly, to an adjustable exhaust port assembly that may be employed in, for example, a respiratory patient interface system. The invention also relates to systems incorporating adjustable exhaust port assemblies. 
     2. Description of the Related Art 
     It is well known to treat a patient with a non-invasive positive pressure support therapy, in which a flow of breathing gas is delivered to the airway of a patient at a pressure greater than the ambient atmospheric pressure. For example, it is known to use a continuous positive airway pressure (CPAP) device to supply a constant positive pressure to the airway of a patient throughout the patient&#39;s respiratory cycle to treat obstructive sleep apnea (OSA), as well as other cardio-pulmonary disorders, such as congestive heart failure (CHF) and cheynes-stokes respiration (CSR). Examples of such CPAP devices include the REMstar® family of CPAP devices manufactured by Philips Respironics, Inc. of Murrysville, Pa. 
     A “bi-level” non-invasive positive pressure therapy, in which the pressure of gas delivered to the patient varies with the patient&#39;s breathing cycle, is also known. Such a bi-level pressure support system provides an inspiratory positive airway pressure (IPAP) that is greater than an expiratory positive airway pressure (EPAP). IPAP refers to the pressure of the flow of gas delivered to the patient&#39;s airway during the inspiratory phase; whereas EPAP refers to the pressure of the flow of gas delivered to the patient&#39;s airway during the expiratory phase. Such a bi-level mode of pressure support is provided by the BiPAP® family of devices manufactured and distributed by Phillips Respironics, Inc. 
     Auto-titration positive pressure therapy is also known. With auto-titration positive pressure therapy, the pressure of the flow of breathing gas provided to the patient changes based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. An example of a device that adjusts the pressure delivered to the patient based on whether or not the patient is snoring is the REMStar Auto family of devices manufactured and distributed by Respironics, Inc. 
     Other modes of providing positive pressure support to a patient are known. 
     For example, a proportional assist ventilation (PAV®) mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient&#39;s breathing effort to increase the comfort to the patient. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient. 
     For purposes of the present invention, the phrases “pressure support device”, “pressure generating device”, and/or “pressure generator” (used interchangeably herein) refer to any medical device adapted for delivering a flow of breathing gas to the airway of a patient, including a ventilator, CPAP, PAV, PPAP, or bi-level pressure support device. The phrases “pressure support system” and/or “positive pressure support system” (used interchangeably herein) include any arrangement or method employing a pressure support device and adapted for delivering a flow of breathing gas to the airway of a patient. 
     In a conventional pressure support system, a flexible conduit couples the pressure support device to a patient interface device. The flexible conduit forms part of what is typically referred to as a “patient circuit”, which carries the flow of breathing gas from the pressure support device to patient interface device. The patient interface device connects the patient circuit with the airway of the patient so that the flow of breathing gas is delivered to the patient&#39;s airway. Examples of patient interface devices include a nasal mask, nasal and oral mask, full face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, or hood. 
     In a non-invasive pressure support system, i.e., a system that remains outside the patient, a single-limb patient circuit is typically used to communicate the flow of breathing gas to the airway of the patient. An exhaust port (also referred to as an exhalation vent, exhalation port, and/or exhaust vent) is provided in the patient circuit and/or the patient interface device to allow exhaust gas, such as the exhaled gas from the patient, to vent to atmosphere. 
     A variety of exhalation ports are known for venting gas from a single-limb patient circuit. For example, U.S. Pat. No. Re. 35,339 to Rappoport discloses a CPAP pressure support system wherein a few exhaust ports are provided directly on the patient interface device, i.e., in the wall of the mask. Such exhaust ports are of fixed size which, while optimum for gas flows at particular pressures, are less than ideal for other situations. 
     Current pressure generating devices used for treating sleep apnea can supply patient delivery pressures ranging from 4 to 20 cmH 2 O in 1/2 cmH 2 O increments. The volume of inspired and expired air in a patient is determined by an individuals&#39; physiology, and the same amount of air delivered to the patient must be exhausted to the atmosphere to eliminate CO 2  rebreathing within the circuit. Fixed size exhaust ports provide different flow rates at different pressures, thereby exhausting a low volume of air at low pressures and higher amounts at high pressures. This discrepancy may cause inadequate venting at low pressure or excess venting at high pressure. Present exhalation ports compromise between the two extremes to provide safe leak rates at both extremes, but they are not designed for a specific leak rate. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the invention, an exhaust port assembly for use in a system for delivering a flow of gas from a pressure generating device to the airway of a patient is provided. The exhaust port assembly comprises: a first member structured to be in communication with the flow of gas and a second member moveably coupled to the first member. The first and second members define a cross-sectional area of an exhaust port which is structured to allow the passage therethrough of exhaust gases from the flow of gas. The second member is moveable among a first position in which the exhaust port has a first cross-sectional area and a second position in which the exhaust port has a second cross-sectional area different than the first cross-sectional area. 
     The first member may comprise a portion of a patient interface or a portion of a patient circuit and may include a first aperture of predetermined cross-sectional area formed therein. The second member may comprise a dial-like member having a plurality of second apertures of varying cross-sectional areas formed therein, the second member being rotatably coupled to the first member in a manner such that each of the second apertures may be selectably aligned with the first aperture. The cross-sectional area of the exhaust port may be defined by the one of the plurality of second apertures aligned with the first aperture. 
     The first member may comprise at least a portion of a first tubular member structured to conduct the flow of gas therethrough and the second member may comprise at least a portion of a second tubular member disposed about the first member. The first tubular member may disposed about a longitudinal axis and the second member may be slidable axially along the longitudinal axis. 
     The first member may comprise an aperture having a length disposed parallel to the longitudinal axis and a width disposed perpendicular to the longitudinal axis, the width varying along the length thereof and the second member may be disposed to selectively block a portion of the aperture. The cross-sectional area of the exhaust port may be defined by a portion of the aperture not blocked by the second member. 
     The first tubular member may be disposed about a longitudinal axis and the second member may be rotatable about the longitudinal axis. The first member may comprise a first aperture having a length disposed perpendicular to the longitudinal axis and a width disposed parallel to the longitudinal axis, the width varying along the length thereof. The second member may comprise a second aperture having a length disposed along the longitudinal axis, the length being equal to or greater than the width of the first aperture. The cross-sectional area of the exhaust port may be defined by a portion of the first aperture aligned with the second aperture. 
     The first member may comprise a first aperture of predetermined cross-sectional area formed therein. The second member may comprise a plurality of second apertures of varying cross-sectional areas equal to, or smaller than, the cross sectional area of the first aperture, formed therein. The second member may be rotatably coupled to the first member in a manner such that each of the second apertures may be selectably aligned with the first aperture. The cross-sectional area of the exhaust port may be defined by the one of the plurality of second apertures aligned with the first aperture. 
     The first member may comprise a plurality of first apertures of varying cross-sectional areas formed therein. The second member may comprise a second aperture of predetermined cross-sectional area formed therein, the predetermined cross-sectional area of the second aperture being equal to, or larger than any of the cross-sectional  areas of the plurality of first apertures. The second member may be rotatably coupled to the first member in a manner such that the second aperture may be selectably aligned with each of the plurality of first apertures. The cross-sectional area of the exhaust port may be defined by the one of the plurality of first apertures to which the second aperture is aligned. 
     The first member may comprise an aperture having a cross-sectional area and the second member may comprise a plurality of second members slidably disposed about the periphery of the aperture. The cross-sectional area of the exhaust port may be defined by a portion of the aperture not blocked by the plurality of second members. 
     As another aspect of the invention, a system for delivering a flow of treatment gas to the airway of a patient is provided. The system comprises a pressure generating device, a patient interface , a patient circuit structured to deliver the flow of treatment gas from the pressure generating device to the patient interface, and an exhaust port assembly as previously discussed. 
     These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a known pressure support system adapted to provide a regimen of respiratory therapy to a patient; 
         FIGS. 2 ,  3 ,  4 A,  5 A,  6 A,  7 A and  8 A show example embodiments of exhaust port assemblies according to embodiments of the present invention; and 
         FIGS. 4B ,  5 B,  6 B,  7 B and  8 B, respectively, show the exhaust port assemblies of  FIGS. 4A ,  5 A,  6 A,  7 A and  8 A disposed in second positions in which the exhaust port size has been selectively varied. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Directional phrases used herein, such as, for example and without limitation, top, bottom, left, right, upper, lower, front, back, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. 
     As employed, herein, the statement that two or more parts or components are “coupled” together shall mean that the parts are joined or operate together either directly or through one or more intermediate parts or components. 
     As employed herein, the statement that two or more parts or components “engage” one another shall mean that the parts exert a force against one another either directly or through one or more intermediate parts or components. 
     As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality) and the singular form of “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise. As employed herein, the term “define” shall mean that one or more elements form the boundaries of a particular element. 
     A system  2  adapted to provide a regimen of respiratory therapy to a patient is generally shown in  FIG. 1 . System  2  includes a pressure generating device  4 , a patient circuit  6 , a patient interface device  8 , and an exhaust port assembly  10  (shown schematically in dashed line) included on an elbow  11  along patient circuit  6 . Although system  2  is discussed as including pressure generating device  4 , patient circuit  6 , and patient interface device  8 , it is contemplated that other systems may be employed while remaining within the scope of the present invention. For example, and without limitation, a system in which the pressure generating device is coupled to a patient interface device having an integrated exhaust port assembly  10  is contemplated. 
     Pressure generating device  4  is structured to generate a flow of breathing gas and may include, without limitation, ventilators, constant pressure support devices (such as a continuous positive airway pressure device, or CPAP device), variable pressure devices (e.g., BiPAP®, Bi-Flex®, or C-Flex™ devices manufactured and distributed by Philips Respironics of Murrysville, Pa.), and auto-titration pressure support devices. 
     Patient circuit  6  is structured to communicate the flow of breathing gas from pressure generating device  4  to patient interface device  8 . Typically, patient circuit  6  includes a conduit or tube which couples pressure generating device  4  and patient interface device  8 . In the current embodiment, conduit  6  includes an elbow  11  coupled to the interface device  8  which includes exhaust port assembly  10  which allows for the venting of exhaust gases  12  therefrom. 
     Patient interface device  8  is typically a nasal or nasal/oral mask structured to be placed on and/or over the face of a patient. Any type of patient interface device  8 , however, which facilitates the delivery of the flow of breathing gas to, and the removal of a flow of exhalation gas from, the airway of such a patient may be used while remaining within the scope of the present invention. In the example shown in  FIG. 1 , patient interface device  8  includes cushion  8   a,  rigid shell  8   b,  and forehead support  8   c.  Straps (not shown) may be attached to shell  8   b  and forehead support  8   c  to secure patient interface device  8  to the patient&#39;s head. 
     An opening in shell  8   b,  to which exhaust elbow  11  is coupled, allows the flow of breathing gas from pressure generating device  4  to be communicated to an interior space defined by shell  8   b  and cushion  8   a , and then, to the airway of a patient. The opening in shell  8   b  also allows the flow of exhalation gas (from the airway of such a patient) to be communicated to elbow  11  and exhaust port assembly  10  in the current embodiment. Although illustrated in a separate elbow component  11  in  FIG. 1 , it is contemplated that exhaust port assembly  10  may be incorporated into, for example and without limitation, patient interface  8  and/or different variations of patient circuit  6  while remaining within the scope of the present invention. 
     Having thus described the general components of system  2 , detailed descriptions of example exhaust port assemblies in accordance with the present invention will now be described in reference to  FIGS. 2 ,  3 ,  4 A and  4 B,  5 A and  5 B,  6 A and  6 B,  7 A and  7 B, and  8 A and  8 B. 
     Referring to  FIG. 2 , an example embodiment of an exhaust port assembly  20  is shown disposed in a portion  22  of a patient interface device, such as patient interface device  8  previously discussed. Portion  22  forms a first member of exhaust port assembly  20  as portion  22  includes a first aperture  24  of predetermined cross-sectional area formed therein which is structured to permit the flow of exhaust gases therethrough. Although shown as being generally circular, it is to be appreciated that first aperture  24  may be of other shape without varying from the scope of the present invention. Continuing to refer to  FIG. 2 , exhaust port assembly  20  further includes a second member  26  rotatably coupled to portion  22 . Second member  26  is formed generally as a dial-like member and includes a first portion  26   a  extending generally from portion  22 , and a second portion  26   b  disposed on the opposite (patient facing) side of portion  22 . Second portion  26   b  includes a plurality of second apertures  28   a - 28   i  of varying cross-sectional areas formed therein. 
     In use, exhaust port assembly  20  allows for the flow of exhaust gases therethrough to be selectively adjusted by adjusting the cross-sectional area of the actual exhaust port  30  as defined by the first member (portion  22 ) and the second member (dial-like member  26 ). In the embodiment shown in  FIG. 2 , the exhaust port  30  has a cross-sectional area equal to that of the second aperture  28   g,  as second aperture  28  is shown aligned with first aperture  24 . The cross-sectional area of exhaust port  30  may be selectively varied by rotating second member  26  with respect to portion  22  so that another one of second apertures  28   a - 28   i  is generally aligned with first aperture  24 . 
     In order to inhibit the potential undesired escape of gases through anywhere other than through the selected one of second apertures  28   a - 28   i  and first aperture  24 , second portion  26   b  of second member  26  is generally sealed with the patient side (not numbered) of portion  22 . As shown in the example embodiment of  FIG. 2 , first portion  26   a  of second member  26  may be provided with indicia  32  which provide a suggestion of the exhaust port  30  to be used with particular operating pressures. 
       FIG. 3  shows another example of an exhaust port assembly  20 ′ similar to exhaust port assembly  20  previously discussed. Exhaust port assembly  20 ′ operates in a similar manner as exhaust port assembly  20 , however exhaust port assembly  20 ′ instead provides indicia  32 ′ on second portion  26   b ′ of second member  26 . Such indicia  32 ′ corresponding to the selected second aperture (second aperture  28   f  is shown selected in the example of  FIG. 3 ) is viewable by a user through a viewing aperture  34  provided in portion  22 . Viewing aperture  34  may be provided as a cut out portion or as a clear portion of portion  22  without varying from the scope of the present invention. 
       FIGS. 4A and 4B  show another example of an exhaust port assembly  40  according to another embodiment of the present invention shown in two different positions. Exhaust port assembly  40  includes a first member  42  disposed generally about a longitudinal axis  44 . First member  42  is formed as a generally tubular member structured to conduct the flow of gas therethrough, such as a portion of, or a coupling connected with conduit  6  of  FIG. 1 . First member  42  includes an aperture  46  (shown partially in hidden line) having a length L disposed parallel to longitudinal axis  44  and a width W disposed perpendicular to longitudinal axis  44 . The width W varying along length L. 
     Continuing to refer to  FIGS. 4A and 4B , exhaust port assembly  40  also includes a second member  48  formed generally as a tubular member disposed about first member  42  such that second member  48  is slidable (as shown by arrow D) relative to first member  42  along longitudinal axis  44  such that second member  48  may selectively block a first portion  46   a  of aperture  46 , while leaving a second portion  46   b  of aperture  46  open to the surrounding environment. Second portion  46   b  thus defines an exhaust port  50  of exhaust port assembly  40 , through which gases may exit first member  42 . As shown in  FIG. 4A , second member  48  is positioned in a first position covering a large area (first portion  46   a ) of aperture  46 , thus leaving a small area (second portion  46   b ) uncovered thus defining an exhaust port  50  of relatively small cross-sectional area. In contrast,  FIG. 4B  shows second member  48  positioned in a second position in which a smaller area (first portion  46   a ) of aperture  46  is covered, thus leaving a larger area (second portion  46   b ) of aperture open to form exhaust port  50 . Although shown in two particular positions, it is to be appreciated that second member  48  may be positioned in any number of positions from fully covering aperture  46  (and thus not allowing any flow therethrough) to not covering and portion of aperture  46  (and thus not obstructing any flow) without varying from the scope of the present invention. 
       FIGS. 5A and 5B  show yet another example of an exhaust port assembly  60  according to another embodiment of the present invention shown in two different positions. Exhaust port assembly  60  includes a first member  62  disposed generally about a longitudinal axis  64 . First member  62  is formed as a generally tubular member structured to conduct the flow of gas therethrough, such as a portion of, or a coupling connected with conduit  6  of  FIG. 1 . First member  62  includes a first aperture  66  (shown partially in hidden line) having a length l disposed perpendicular to longitudinal axis  64  and a width w disposed parallel to longitudinal axis  64 . The width w varying along length  1 . 
     Continuing to refer to  FIGS. 5A and 5B , exhaust port assembly  60  also includes a second member  68  having a second aperture  70  formed therein, second aperture  70  having a length l 2 , which is equal to or greater than the width w of the first aperture, disposed along (parallel to) longitudinal axis  64 . Second member  68  is formed generally as a tubular member disposed about first member  62  such that second member  68  is rotatable (as shown by arrow R) relative to first member  62  about longitudinal axis  64  such that second aperture  70  of second member  68  may selectively block a one or more first portions  66   a  of first aperture  66 , while selectively exposing a second portion  66   b  of aperture  66  open to the surrounding environment. Second portion  66   b  thus defines an exhaust port  72  of exhaust port assembly  60  through which gases may exit first member  62 . As shown in  FIG. 5A , second member  68 , and thus second aperture  70  is positioned in a first position in which only a small area (second portion  66   b ) of aperture  66  is exposed, thus defining an exhaust port  72  of relatively small cross-sectional  area. In contrast,  FIG. 5B  shows second member  68 , and thus second aperture  70  positioned in a second position in which a larger area (second portion  66   b ) of aperture  66  is exposed, thus defining an exhaust port  72  of relatively large cross-sectional area. Although shown in two particular positions, it is to be appreciated that second member  68 , and thus second aperture  70 , may be positioned in any number of positions from fully not exposing any of first aperture  66  (and thus not allowing any flow therethrough) to exposing a relatively large portion of aperture  66  (and thus allowing a relatively large flow) without varying from the scope of the present invention. 
       FIGS. 6A and 6B , as well as  FIGS. 7A and 7B , show further embodiments of exhaust port assemblies according to the present invention which utilize a combination of some of the concepts previously discussed. 
     Referring to  FIGS. 6A and 6B , exhaust port assembly  80  includes a first member  82  disposed generally about a longitudinal axis  84 . First member  82  is formed as a generally tubular member structured to conduct the flow of gas therethrough, such as a portion of, or a coupling connected with conduit  6  of  FIG. 1 . First member  82  includes a first aperture  86  (shown in hidden line) having a generally circular cross-section (although other shapes may be employed without varying from the scope of the present invention). Exhaust port assembly  80  further includes a second member  88  having a plurality of second apertures  90   a - 90   d  of varying size formed therein. Second member  88  is formed generally as a tubular member disposed about first member  82  such that second member  88  is rotatable (as shown by arrow R) relative to first member  82  about longitudinal axis  84  such that a selected one of the plurality of second apertures  90   a - 90   d  of second member  88  may be generally aligned with first aperture  86 , thus defining an exhaust port  92  through which gases may exit first member  82 . 
     Like the embodiments described in conjunction with  FIGS. 2 and 3 , exhaust port assembly  80  allows for the flow of exhaust gases therethrough to be selectively adjusted by adjusting the cross-sectional area of the actual exhaust port  92  as defined by first aperture  86  of first member  82  and the selected second aperture ( 90   c  in  FIG. 6A and 90   a  of  FIG. 6B ) of second member  88 . When positioned as shown in  FIG. 6A , exhaust port  92  has a cross-sectional area equal to that of the second aperture  90   c,  as second aperture  90   c  is shown aligned with first aperture  86 . In contrast, when positioned as shown in  FIG. 6B , exhaust port  92  has a cross-sectional area equal to that of the second aperture  90   a,  as second aperture  90   a  is shown aligned with first aperture  86 . In order to inhibit the potential undesired escape of gases through anywhere other than through the selected one of second apertures  90   a - 90   d,  second member  88  is generally sealed with the outer portion (not numbered) of first portion  82 . 
     The example exhaust port assembly  100  of  FIGS. 7A and 7B  generally operates in the same manner as exhaust port assembly  80  previously described, however, exhaust port assembly  100  utilizes a generally opposite arrangement of apertures. More particularly, exhaust port assembly  100  utilizes a first member  102  having a plurality of first apertures  104   a - 104   d  of varying size formed therein, and only a single second aperture  106  formed in a second member  108  rotatably (along arrow R) coupled to first member  102 . Through such arrangement, an exhaust port  109  is defined, which in  FIG. 7A  is defined by first aperture  104   c,  and by first aperture  104   a  in  FIG. 7B . 
       FIGS. 8A and 8B  show an example of an exhaust port assembly  110  which employs an iris-type mechanism for varying the size of an exhaust port  112 . The iris-type mechanism operates by providing a plurality of second members  114  about the periphery  116  of an aperture  118  formed in a first member  120  which is in contact with a flow of exhaust gas expelled from a patient. The plurality of second members  114  act to block a first portion  118   a  of aperture  118 , thus leaving another portion  118   b  of aperture  118  unobstructed, thus defining the area of exhaust port  112 . It is to be appreciated that second members  118  may be actuated manually or though automated means, similar to the shutter mechanism of a camera, thus making such embodiment as shown in  FIGS. 8A  and  8 B particularly suitable to patient interface systems in which the sizing of exhaust port  112  may be controlled through computerized means. 
     In addition to the embodiment illustrated, it is to be appreciated that the concepts of the present invention may also be carried out by providing a plurality of apertures and then selectively exposing or covering the entirety or portions of individual apertures to achieve the desired exhaust port sizing (i.e., 1 port, 1-½ ports, 2 ports, etc.). 
     Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.