Abstract:
A pulmonary function filter includes an adapter, which maybe resilient, allowing the filter to be used on a pulmonary function sensor having a different sized inlet. A pulmonary function sensor and filter combination can be joined by an adapter that may allow such sensor and filter to be joined even though they may have different sized inlet and outlet.

Description:
BACKGROUND OF THE INVENTIONS  
         [0001]    1. Field of the Inventions  
           [0002]    This relates to pulmonary function filters and pulmonary sensor assemblies.  
           [0003]    2. Related Art  
           [0004]    Spirometry is the measurement of the volume of air entering and leaving the lungs, which measurements may indicate typical or impaired lung function. Such measurements may also be used to indicate changes in lung function, such as may occur as a result of an asthma condition. Spirometry systems can measure, record and assess flow/volume parameters, and such systems can tabulate, plot and display the desired pulmonary function information based on the measured parameters.  
           [0005]    The equipment used in spirometry may include a pneumotachometer sensor for measuring lung function coupled to a microprocessor for analyzing data and/or for transmitting data to another site. Users exhale into the pneumotachometer through a mouth piece, and the pneumotachometer translates the exhale flow and time information into electronic data for analysis, display, storage or transmission. The pneumotachometer may be reusable, while the mouth piece is be typically disposable.  
           [0006]    Typical pulmonary function measurement systems use a single-use, disposable filter between the mouth piece and the sensor. The filter is intended to prevent cross contamination by removing moisture droplets and bacteria from the respiratory air before the air reaches the sensor. The filter is preferably relatively short along the flow axis to minimize the amount of dead air in the flow path so that the space occupied by the filter has a minimum effect on the flow being sensed by the sensor. On the other hand, the diameter or cross-sectional area of the filter material is preferably relatively large so as to reduce any impediment to free air flow through the filter.  
           [0007]    Sensors, as well as the filters used with the sensors, come in a number of shapes and sizes, and the sizes of the sensor inlets to which the filter outlets are attached vary as well. As a result, filters are made to have different outlet sizes to accommodate the different sensor inlet sizes. Likewise, any given filter generally can be used only with sensors having the appropriate sized inlet opening, and not with others without the use of an adapter. Use of a filter having an outlet not properly sized to fit the sensor inlet may result in leakage of air flow around the filter-sensor connection, leading to inaccurate results. Additionally, filter-sensor connections through hard plastic materials may not always provide the desired airtight seal.  
         SUMMARY OF THE INVENTIONS  
         [0008]    An adapter is provided for use between a pulmonary function filter and a sensor. The adapter may allow filters having different outlet sizes to be used on a given sensor. In one form, the adapter may allow a filter having a given outlet size to be used on sensors having different inlet sizes. The adapter may also contribute to an enhanced airtight seal for the filter and/or sensor.  
           [0009]    In one example, a pulmonary function filter includes an adapter having a portion extending radially inward to form an opening for receiving an inlet of a sensor. The radially extending portion would then extend around the sensor inlet, preferably forming an airtight seal around the sensor inlet. In one example, the radially extending portion is flexible to accommodate sensor inlets of different sizes and/or shapes. In another example, the radially extending portion is resilient so as to be biased toward the outer surface of the sensor inlet, contributing to the formation of an airtight seal.  
           [0010]    In another example, a pulmonary function filter includes a seal element on an outlet to form a seal about an inlet of a sensor. In one form, the seal element forms an airtight seal about the sensor inlet. The seal element can be formed from a resilient or flexible material, and in one preferred form is formed from an elastomeric material, such as may be suitable for equipment used in conjunction with pulmonary function analyzers.  
           [0011]    In a further example, a pulmonary function filter includes an adapter formed from a resilient material, wherein the adapter is configured to fit around an inlet of a sensor. In one form, the adapter includes a portion extending radially toward a center so as to form an opening, for example a circular opening and/or an opening that is coaxial with a central axis of the filter. In one form, the adapter may be removable, and in another form the adapter may be bonded, welded, co-molded or otherwise fixed to the filter.  
           [0012]    In another example, a sensor combination of a pulmonary function filter and a pulmonary function sensor includes an adapter having a first sleeve extending about a surface of the filter outlet and a second adapter element extending about an inlet on the sensor. In one form, the adapter is formed from the resilient material, and preferably forms an airtight seal about the outlet of the filter and the inlet of the sensor. The filter outlet may have a first diameter and the sensor inlet may have a second diameter less than the filter outlet diameter, and the second adapter element may extend radially inward to engage the sensor outlet. In one preferred form, the adapter is formed entirely from a resilient material, and may be formed as a single, monolithic component.  
           [0013]    Aspects of the inventions are set forth more fully below in conjunction with drawings, a brief description of which follows. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a side elevation view of a pulmonary function sensor combination having a sensor, pulmonary function filter and mouth piece.  
         [0015]    [0015]FIG. 2 is an isometric view of a pulmonary function filter for use with the combination of FIG. 1.  
         [0016]    [0016]FIG. 3 is a longitudinal cross-section of the pulmonary function filter of FIG. 2.  
         [0017]    [0017]FIG. 4 is an isometric view of a pulmonary function filter and adapter for use with the combination of FIG. 1.  
         [0018]    [0018]FIG. 5 is an outlet end plan view of the pulmonary function filter combination of FIG. 4.  
         [0019]    [0019]FIG. 6 is a longitudinal cross-section of the adapter of FIG. 4.  
         [0020]    [0020]FIG. 7 is an end plan view of the adapter of FIG. 6. 
     
    
     DETAILED DESCRIPTION  
       [0021]    The following specification taken in conjunction with the drawings sets forth the preferred embodiments of the present inventions in such a manner that any person skilled in the art can make and use the inventions. The embodiments of the inventions disclosed herein are the best modes contemplated for carrying out the inventions in a commercial environment, although it should be understood that various modifications can be accomplished within the parameters of the present inventions.  
         [0022]    A pulmonary function filter is described that includes an adapter enabling the filter to be placed on a sensor whose inlet size was such that the sensor would not previously have accommodated the filter. The filter can also be used on sensors for which it has previously been used.  
         [0023]    Pulmonary function filters and the sensors with which they are used can take a number of configurations, sizes and shapes. The filter described herein will be one similar to that manufactured by Creative Biomedics, and discussed in U.S. Pat. No. 6,131,573, incorporated herein by reference. The pneumotachometer referenced herein may be any sensor that accommodates a pulmonary function filter, and may be one such as that marketed by Creative Biomedics with their DX-PC spirometry system. However, it should be understood that the present inventions can be used with a number of filters and a number of sensors other than the specific ones mentioned. The specific ones mentioned herein will be discussed as examples only, and it will be understood that the inventions are applicable to other designs.  
         [0024]    A pulmonary function analysis system or combination  50  (FIG. 1) in the example described herein includes a pulmonary function filter  52  with an inlet  54 , an outlet  56  and a filter element  58  (FIG. 3) supported and positioned between the inlet and the outlet. An example of the pulmonary function filter shown in FIG. 3 is discussed in U.S. Pat. No. 6,131,573. A mouth piece  60  (FIG. 1) is typically inserted into the inlet  54  so that a user can force an expiratory breath into the filter.  
         [0025]    The outlet  56  of the filter  52  is coupled to an inlet  62  of a sensor  64  (FIG. 1) so that the sensor  64  receives the exhaled air. The outlet of the filter is positioned adjacent, and may be disposed partly around the inlet  62  of the sensor. The sensor will typically include a housing  66  containing within it a material (not shown) for generating a slight pressure drop across the material, and several sensors or transducers at the upstream and downstream sides of the material for detecting the pressure differential across the material. The transducers generate electrical signals representing the pressure differential, which signals are then transmitted over an appropriate cable  68  to a microprocessor or other controller  70  for receiving the data and combining it with other data to be used in the analysis. The controller may include appropriate software for analyzing the data and generating the desired representations of the data, such as a flow/volume curve, tabulated data or other information for the user, a practitioner or other personnel. The controller may also include a display, printer, data entry keys, control keys such as calibration keys and the like, ports for communicating with other devices, as well as other components.  
         [0026]    The pulmonary function filter (FIGS.  1 - 5 ) is preferably symmetrical about a central longitudinal axis  72  and includes a first housing portion  74  having the inlet  54  extending along the axis toward an end into which the mouth piece is inserted. The inlet has a first outside diameter  76  and an inside diameter  78  (FIG. 3), wherein the outside diameter of the mouth piece  60  is approximately the same as the inside diameter  78  to provide a friction fit. The engagement between the mouth piece  60  and the inside diameter  78  of the inlet  54  is preferably airtight.  
         [0027]    The filter includes a second housing portion  80  joining with the first housing portion  74  in such a way as to preferably sandwich the filter material  58  between them. The axial length of the filter is preferably small so as to minimize dead air space between the inlet and the outlet, while the surface area of the filter element is preferably relatively large in the radial direction to keep low the resistance to air flow. The second housing portion  80  includes the outlet  56 , which has an outside diameter shown in FIG. 3 at  82 . The outlet is typically cylindrical, forming a right circular cylinder to the point where the outlet  56  joins the rest of the second housing portion  80  and is preferably coaxial with the center axis  72  and the inlet. The outer most portion of the outlet is preferably circular in cross-section. Other pulmonary function filters may have an outlet having an intermediate outside diameter  84  while others may have a larger outside diameter  86 , these other outside diameters represented schematically by the lines shown in FIG. 3. It should be understood that the wall thickness of the outlet for any given outside diameter would generally be the same for any given filter, the outer lines shown around the outlet of the filter in FIG. 3 being used to represent the other outlets for simplicity. The filter used with the adapter described herein preferably has a larger outlet diameter, such as that corresponding to be outside diameter  86  (FIG. 3), and one which is larger than the diameter of the filter inlet. The larger outlet diameter enables it to be placed around the outlets of a larger number of sensors.  
         [0028]    The housing portions of the filter are typically formed of a relatively hard or rigid plastic, such as styrene, but other materials may be used such as polypropylene and other plastics. Additionally, the filter can have other shapes and dimensions, and the filter element can be supported in other ways.  
         [0029]    An adapter, junction, interface or seal element  88  (FIGS.  4 - 7 ) is used to couple the filter to the sensor. In the example shown in FIGS.  4 - 7 , the adapter includes a first wall portion or sleeve  90  extending axially along the wall  92  of the outlet  56  (FIG. 4) a sufficient distance to form a reliable airtight seal between the first wall portion  90  and the wall  92 . A second portion or second element  94  extends radially inward in the direction of the central axis  72  (not shown in FIG. 6). The second portion  94  extends inwardly from a transition portion  96  to a wall  98  forming an opening  100  confluent with the opening  102  in the outlet  56  (FIG. 3). The wall  98  preferably forms an airtight seal about the outer surface of the sensor inlet  62 . In one example, the second portion  94  is formed from a resilient soft plastic to adequately grip the outer surface of the inlet  62 . In another example, the wall  98  or other surface of second portion  94  that contacts the surface of the inlet  62  has a surface that is sufficiently tacky to form the desired airtight seal. Other surfaces besides wall  98  may contact the surface of the inlet  62 , depending on how the filter and adapter are manipulated onto the inlet  62 , for example through rotation, axial sliding, or both, and on the sensor inlet size.  
         [0030]    The opening  100  is preferably circular as shown in FIGS.  4 - 7 . While other configurations of the opening are possible, many sensor inlets  62  are round and could be accommodated by round openings  100 . In the example shown in the drawings, the shape of the opening  100  conforms to the outer shape of the sensor  62 . The dimensions of the opening  100  as defined by the wall  98  may be smaller than the smallest outside diameter of sensor inlet  62  to which the filter will be attached. In one example, the adapter wall  90  contacts the surface  92  of the outlet over a given surface area, and the second portion and/or wall  98  contact the sensor inlet  62  over a surface area less than the surface area of contact over the filter outlet. These relative surface areas may enhance the ability of the adapter to remain in the proper position on the outlet  56 . In the example where the adapter  88  is placed on the outlet having the larger outside diameter  86 , and the size of the opening  100  is less than the smallest outside diameter of inlet  62 , the filter can be used on sensors having a range of diameters for the inlet  62 . Consequently, the number of different sizes of filters made and stocked can be reduced, thereby reducing part inventory, manufacturing costs, and the like.  
         [0031]    In the example shown in FIGS.  4 - 5 , the adapter  88  is a discrete monolithic structure placed over part of the outside wall  92  of the outlet  56 . In this example, the inside diameter of the wall  90  in its relaxed configuration is preferably less than the outside diameter of the outlet  56  so that the inside surface of the wall  90  grips or frictionally engages the outside surface of the wall  92 . In this example, the adapter  88  can be removable from the filter. In another example, the seal element can be bonded, glued, adhered, welded, dissolved or otherwise fixed to the outlet  56 . The adapter could also be heat-shrunk onto the wall of the outlet. The wall  90  could extend over a substantial portion of the wall  92 , a relatively short portion of the wall  92 , or could extend only across the rim  104  (FIG. 3) of the outlet. In a further example, the adapter can be monolithic with the second housing  80 . In this further example of the monolithic adapter, the adapter is preferably formed from a different material than the second housing  80 , and may be co-molded with the second housing. The adapter may be a plastic sufficiently soft, resilient and/or flexible to form an airtight seal around one and preferably both of the outlet  56  and the inlet  62 . The adapter can be a thermoplastic elastomer, for example rubber, Neoprene, or other suitable thermoplastic materials.  
         [0032]    The adapter  88  is used to join the filter to the inlet  62  of the sensor, and preferably provides an airtight seal between the filter and the sensor. In one example, the adapter  88  forms an airtight seal with the outlet  56  and forms an airtight seal around the inlet  62 . In the example shown in FIG. 4, the adapter  88  forms an airtight seal around the outlet wall  92 .  
         [0033]    Having thus described several exemplary implementations of the invention, it will be apparent that various alterations and modifications can be made without departing from the inventions or the concepts discussed herein. Such operations and modifications, though not expressly described above, are nonetheless intended and implied to be within the spirit and scope of the inventions. Accordingly, the foregoing description is intended to be illustrative only.