Abstract:
Disclosed are devices and methods for continuous positive airway pressure (CPAP) devices and related medical devices for treating patients susceptible to respiratory illnesses, including respiratory distress syndrome and sleep apnea. The device and methods employ force gauged CPAP nasal interface devices for these purposes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of priority under 35 U.S.C. 119 to U.S. provisional patent application Ser. No. 61/619,699, filed Apr. 3, 2012, and entitled “FORCE GAUGED INFANT CPAP NASAL INTERFACE,” the contents of which are herein incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to continuous positive airway pressure (CPAP) devices and related medical devices for treating patients susceptible to respiratory illnesses, including respiratory distress syndrome and sleep apnea. 
         [0004]    2. Discussion of the Art 
         [0005]    Respiratory Distress Syndrome (RDS) occurs in infants whose lungs have not yet fully developed. The disease is mainly caused by a lack of a protective substance called surfactant, which helps the lungs inflate with air and keeps the air sacs from collapsing. Surfactant normally appears in fully developed lungs but not in infants with RDS. RDS can cause sleep apnea, a condition where an infant stops breathing during sleep for an intermittent period of time. Similar respiratory illnesses in the form acute respiratory distress syndrome and obstructive sleep apnea also affect adults. 
         [0006]    A conventional method for treating RDS in infants and sleep apnea in both infants and adults is through use a Continuous Positive Airway Pressure (CPAP) device. CPAP devices deliver a constant, slightly pressurized, and sometimes humidified supply of air to the infant to ensure a continuous sustainable lung function. 
         [0007]    Common CPAP devices are positioned to an infant&#39;s nasal passages in an inconsistent and often forceful manner. The force applied to the nasal passages frequently leads to pressure sores, broken facial bones, and stunted skeletal development in infants. Studies have shown that infants who received constant positive airway pressure using a CPAP device suffered moderate nasal injuries approximately thirty two percent of the time, and suffered severe nasal injuries twenty five percent of the time. 
         [0008]    Constant positive airway pressure (CPAP) can be delivered through various types of devices and generators. Most CPAP devices include one or two air tubes that attach to an interface. The generator then attaches to a nasal adaptor. The nasal adaptor is sized according to the facial structure of the infant. In many CPAP devices, nasopharyngeal prongs that span from the nares to the nasopharynx are used. These devices interact directly with the infants nasal passages, and are often referred to as nCPAP devices. Although these nCPAP devices fulfill the purpose of providing the infant with constant positive airway pressure, often times these devices cause serious injury to the infant. The force with which an nCPAP device is positioned to the infants face varies considerably. In some cases a tremendous amount of variable force is produced, and because of an infant&#39;s extremely delicate facial tissue, this force commonly results in serious injury. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In a first aspect, a force gauged CPAP device is disclosed. The device includes a housing assembly, a spring, a retention member and a generator. The spring is adapted for coupling to an interior distal wall member of the housing assembly. The generator is disposed slideably within the housing assembly. The retention member maintains the generator within the housing assembly. The spring is adaptively compressed when the generator slideably engages the housing assembly. 
         [0010]    In one respect of the first aspect, the device is used in a method for treating a patient suffering from a respiratory illness. According to the method, the device is administered to the patient. 
         [0011]    In a second aspect, force gauged housing assembly for a CPAP generator is disclosed. The assembly includes a housing assembly, a spring and a retention member. The spring is adapted for coupling to an interior distal wall member of the housing assembly The housing assembly is adapted to permit a generator to be slideably disposed within the housing assembly. The retention member is adapted to maintain a generator within the housing assembly. The spring is adapted for compression when a generator slideably engages the housing assembly. 
         [0012]    In one respect of the second aspect, the assembly is used in a method of using a force gauged CPAP device. The method includes four steps: providing a force gauged housing assembly according to the second aspect; providing a CPAP generator; assembling the CPAP generator into the force gauged housing assembly to provide force gauged CPAP device; and attaching the force gauged CPAP device to a user. 
         [0013]    In another respect of the second aspect, the assembly is used in a method for treating a patient suffering from a respiratory illness. The method includes two steps: assembling a CPAP device from a force gauged housing assembly according to the second aspect and a generator; and administering the assembled force gauged CPAP device to the patient. 
         [0014]    In a third aspect, a maximum force indicator for a CPAP device is disclosed. The indicator includes a plurality of supporting members; an assembly having a base member and two side wall members, wherein the two side wall members are non-displaceably coupled to the base member, and wherein a plurality of cavities are disposed in the distal portion of the assembly to receive the plurality of supporting members; a distal wall member having on its inner wall surface at least one push-block member and the plurality of supporting members attached thereto, wherein the distal wall member is displaceably coupled from the assembly; and a retention member, wherein the retention member maintains the assembly in proximity to a generate when present. 
         [0015]    In one respect of the third aspect, the indicator is used in method with a force gauged CPAP device. The method includes four steps: providing a maximum force indicator of claim  21 ; providing a CPAP generator; assembling the CPAP generator into the maximum force indicator to provide force gauged CPAP device; and attaching the force gauged CPAP device to a user, wherein the operation of the maximum force gauge indicator informs the user about the maximum force gauge levels of CPAP output. 
         [0016]    In another respect of the third aspect, the indicator is used in a method of treating a patient suffering from a respiratory illness. The method includes two steps: assembling a CPAP device from a maximum force indicator and a generator; and administering the assembled force gauged CPAP device to the patient. 
         [0017]    In a fourth aspect, a device adapted to gauge an amount of force applied to a patient during a CPAP nasal insert insertion procedure is disclosed. The device includes a housing assembly, a generator and a spring. The housing assembly includes two vertical side wall members and a vertical distal wall member. The vertical wall member has a spring retention element. The generator includes a distal wall member having an outer surface and two vertical side wall members each having an outer surface, and said generator is translationally engaged to said housing assembly. The spring is disposed in said spring retention element so that said spring is in force communication with said housing assembly and said generator. The generator further comprises a visual indicator positioned for readability on at least one vertical side wall member outer surface, said visual indicator being calibrated to said spring and configured for gauging an amount of force applied to a patient during a CPAP nasal insert insertion procedure. 
         [0018]    In a fifth aspect, a system for applying a CPAP nasal insert to a patient is disclosed. The system includes a CPAP nasal insert and a device. The device includes a housing assembly, a generator and a spring. The housing assembly includes two vertical side wall members and a vertical distal wall member, wherein said vertical wall member has a spring retention element. The generator includes a distal wall member having an outer surface and two vertical side wall members each having an outer surface. The generator is translationally engaged to said housing assembly. The spring is disposed in said spring retention element so that said spring is in force communication with said housing assembly and said generator. The generator further comprises a visual indicator positioned or readability on at least one vertical side wall member outer surface. The visual indicator is calibrated to said spring and configured for gauging an amount of force applied to a patient during a CPAP nasal insert insertion procedure. 
         [0019]    In a sixth aspect, a method for applying a CPAP nasal insert to a patient during a CPAP nasal insert insertion procedure is disclosed. The method includes the following steps. The first step is providing a nasal insert. The second step is providing a device for gauging the amount of force applied to the patient during a CPAP nasal insert insertion procedure. The third step is contacting the nasal insert with the device for gauging the amount of force applied to a patient during a CPAP nasal insert insertion procedure. The fourth step is contacting the combined nasal insert and device for gauging the amount for force applied to a patient during a CPAP nasal insert insertion procedure with the patient. The fifth step is compressing the combined insert and device to an amount no greater than determined safe by the visual indicator that is placed on an outward facing surface of the device. The final step is securing straps interwoven with the device to hold the combined nasal insert and device in place on the patient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  depicts a schematic illustrating an exploded perspective view of one preferred embodiment. 
           [0021]      FIG. 2  depicts a schematic illustrating a perspective view of one preferred embodiment similar to that presented in  FIG. 1  in assembled form. 
           [0022]      FIG. 3  depicts a schematic illustrating an exploded perspective view of one preferred embodiment. 
           [0023]      FIG. 4  depicts a schematic illustrating a perspective view of one preferred embodiment similar to that presented in  FIG. 3  in assembled form. 
           [0024]      FIG. 5  depicts a schematic illustrating a perspective view of one preferred embodiment having a no rail members. 
           [0025]      FIG. 6A  depicts a schematic illustrating an exploded perspective view of one preferred embodiment of a maximum force indicator (assembled with generator). 
           [0026]      FIG. 6B  depicts a schematic illustrating an exploded perspective view of one preferred embodiment of a maximum force indicator (generator fully compressed). 
           [0027]      FIG. 6C  depicts a schematic illustrating an exploded perspective view of one preferred embodiment of a maximum force indicator (generator relaxed). 
           [0028]      FIG. 7A  depicts a comparison of Force data for prototype and Airlife device, wherein the graph depicts a box plot of the peak force data. 
           [0029]      FIG. 7B  depicts a comparison of Force data for prototype and Airlife device, wherein the graph depicts histograms of the peak force data. 
           [0030]      FIG. 7C  depicts a comparison of Force data for prototype and Airlife device, wherein the depicts a box plot of the steady state force data. 
           [0031]      FIG. 7D  depicts a comparison of Force data for prototype and Airlife device, wherein the graph depicts histograms of the steady state force data. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    In the following detailed description, reference is made to the accompanying figures, which form a part hereof In the figures, similar symbols typically identify similar components, unless context dictates otherwise. Insofar as possible, like parts and modules have the same reference numeral in the figures. The illustrative embodiments described in the detailed description, figures, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein. 
         [0033]    One preferred embodiment is illustrated in  FIGS. 1 and 2 . In  FIG. 1 , device  100  includes housing assembly  110 , retention cap  140  and generator  170 . In  FIG. 2 , device  100  is assembled with generator  170  located inside housing assembly  110  with retention cap  140  attached to housing assembly  110  at interface  160 . 
         [0034]    Housing assembly  110  of device  100  preferably includes the following features. Housing assembly  110  includes horizontal base member  112 , vertical distal wall member  114  and two vertical side wall members  116 . Horizontal base member  112  is preferably substantially plain surface. Vertical distal wall member  114  includes an inner wall surface  118 . Vertical side wall members  116  include an inner wall surface  120 , an outer wall surface  122  and a proximal surface  124 . 
         [0035]    Spring retention element  126  accommodates spring  128 . Spring retention element  126  can be any structure amenable for retaining spring  128 , such as a recess; a pocket; one or more rods or like structures; immobilized tie-downs, such as clips, staples, sutures, tapes, wires, rivets and the like; an adhesive, such as glue, epoxy and the like; among others. Spring retention element  126  is preferably a recess located within inner wall surface  118 . Spring  128  is preferably in continuous mechanical communication with the housing assembly  110  during operation of device  100 . 
         [0036]    A plurality of pin holes  130  are preferably located on proximal surface  124  of vertical side wall members  116 . Pin holes  130  can be of any shape and size, provided that pin holes  130  mate with pins  150  of retention cap  140  to ensure securely fastened interface  160 . Preferably, pin holes  130  are substantially round in shape. 
         [0037]    Housing assembly  110  preferably includes one guide groove  132  and one stop groove  134  located on inner surface  120  of each vertical side member  116 . Both guide groove  132  and stop groove  134  run along the inner wall surface  120  and terminate at proximal surface  124  and preferably at the junction of inner wall surface  120  with inner wall surface  118 . 
         [0038]    Grooves  132  and  134  can be located at any position along the dimension of vertical side member  116  of housing assembly  110 , provided that the position(s) of grooves  132  and  134  do not interfere with the structural integrity of pin holes  130 . Thus, in the embodiment of device  100  illustrated in  FIG. 1 , grooves  132  and  134  can have the inverse relative orientation on each vertical side member  116 . For example, where guide groove  132  is positioned below stop groove  134  on the vertical dimension of one vertical side member  116  (see  FIG. 1 , positions of grooves  132  and  134  on right vertical side member  116 ), guide groove  132  is positioned above stop groove  134  on the vertical dimension of the opposing vertical side member  144  (see  FIG. 1 , positions of grooves  132  and  134  left vertical side member  116 ). 
         [0039]    In alternate embodiments of device  100 , grooves  132  and  134  can have the same relative orientation on each vertical side member  116  of housing assembly  110 . For example, guide groove  132  is positioned below stop groove  134  on the vertical dimension of both vertical side members  116 . 
         [0040]    Referring to  FIG. 1 , grooves  132  and  134  preferably have dissimilar sizes. Guide groove  132  preferably has a substantially uniform size and shape throughout its length that is smaller than the corresponding size and shape of stop groove  134 . The reason for stop groove  134  having an increased size throughout its length relative to guide groove  132  is attributed to the fact that stop groove  134  accommodates a larger rail than that which guide groove  132  accommodates. Yet the shapes and sizes of grooves  132  and  134  need not be identical for their like counterparts on the opposing vertical side member  116 . 
         [0041]    Referring to  FIG. 2 , preferred features of grooves  132  and  134  of housing assembly  110  are that they form preferably substantially aligned, continuous, extended grooves with grooves  152  and  154  of retention cap  140  when housing assembly  110  when is mated with retention cap  140  at interface  160 . In particular, guide grooves  132  of housing assembly  110  and guide grooves  152  of retention cap  140  together preferably form an extended guide groove when housing assembly  110  and retention cap  140  are mated at interface  160 . Likewise, stop grooves  134  of housing assembly  110  and stop grooves  154  of retention cap  140  together form an extended stop groove when housing assembly  110  and retention cap  140  are mated at interface  160 . A substantially aligned, continuous and extended glide groove and extended stop grove is formed in device  110  if generator  170  configured with corresponding guide rails and stop rails can translationally slide with ease (that is, without substantial frictional contact or force being applied) along at least a portion the extended guide groove and extended stop groove at interface  160 , at least until the until stop rail blocker  199  encounters stop groove  154 . 
         [0042]    Referring to  FIG. 1 , housing assembly  110  also includes head-strap element  136  positioned on outer wall surface  122  of vertical wall members  116 . 
         [0043]    Retention cap  140  of device  100  preferably includes the following features. Retention cap  140  includes a horizontal base member  142  and two vertical side members  144 . Vertical side members  144  include distal surface  146  that contacts housing assembly  120  within assembled device  100  and inner side surface  148  that contacts generator  160  within assembled device  100 . 
         [0044]    Retention cap  140  preferably includes a plurality of pins  150  located on distal surface  146  of each vertical side member  144 . Pins  150  can be of any shape and size, provided that pins  150  mate with pin holes  130  of housing assembly  110  to ensure securely fastened interface  160 . Preferably, pins  150  are substantially round in shape. 
         [0045]    Retention cap  140  preferably includes one guide groove  152  and one stop groove  154  located on inner surface  150  of each vertical side member  144  of retention cap  140 . Grooves  152  and  154  extend preferably throughout the width of inner surface  150 . Grooves  152  and  154  can be located at any position along the dimension of vertical side member  144  of retention cap  140 , provided that the position(s) of grooves  152  and  154  do not interfere with the structural integrity of pins  150 . Thus, in the embodiment of device  100  illustrated in  FIG. 1 , grooves  152  and  154  can have the inverse relative orientation (termed “offset”) on each vertical side member  144 . For example, where guide groove  152  is positioned below stop groove  154  on the vertical dimension of one vertical side member  144  (see  FIG. 1 , positions of grooves  152  and  154  on right vertical side member  144 ), guide groove  152  is positioned above stop groove  154  on the vertical dimension of the opposing vertical side member  144  (see  FIG. 1 , positions of grooves  152  and  154  left vertical side member  144 ). 
         [0046]    In alternate embodiments of device  100 , grooves  152  and  154  can have the same relative orientation on each vertical side member  144  of retention cap  140 . For example, guide groove  152  is positioned below stop groove  154  on the vertical dimension of both vertical side members  144 . 
         [0047]    Referring to  FIG. 1 , grooves  152  and  154  can have substantially the same shape and size, which represents a preferred embodiment. Yet the shapes and sizes of grooves  152  and  154  need not be identical to one another or to their like counterpart on the opposing vertical side member  144 . For example, guide grooves  152  can differ with respect to each other and to stop groove  154  in terms of their respective shape (for example, square, rectangular, triangular, ovoid, etc.) and size (longer, deeper). Likewise, stop grooves  154  can differ with respect to each other and to guide groove  152  in terms of their shape and size. 
         [0048]    Preferred features of grooves  152  and  154  of retention cap  140  are that they form preferably substantially aligned, continuous and extended grooves with grooves  132  and  134  of housing assembly  110  when retention cap  140  is mated with housing assembly  110  at interface  160 . Thus, guide grooves  152  of retention cap  140  and guide grooves  132  of housing assembly  110  together preferably form an extended guide grooves when the retention cap  140  and housing assembly  110  are mated at interface  160 . Likewise, stop grooves  152  of retention cap  140  and stop grooves  134  of housing assembly  110  together preferably form an extended guide groove when retention cap  140  and housing assembly  110  are mated at interface  160 . A substantially aligned, continuous and extended glide groove and extended stop grove is formed in device  110  if generator  170  configured with corresponding guide rails and stop rails can translationally slide with ease (that is, without substantial frictional contact or force being applied) along at least a portion the extended guide groove and extended stop groove at interface  160 , at least until stop rail blocker  199  encounters stop groove  154 . 
         [0049]    Generator  170  of device  100  preferably includes the following features. Generator  170  includes a top surface member  172 , a bottom surface  174 , a distal wall member  176 , a proximal wall recess member  178  and two vertical side wall members  180 . Distal wall member  176  includes outer surface  182 . Vertical side wall members  180  include outer surface  184 , proximal surface  186  and distal surface  188 . 
         [0050]    Operational structures of generator  170  pertaining to CPAP functions are well known in the art and only briefly described herein. Air channel adaptors  189  are located and extend through top surface member  172 . Air channel adaptors  189  provide, in part, fluid communication with common gas supply tubes via tubing (not shown) to supply an appropriately humidified O 2 /N 2  gas mixture to the interior of generator  170 . Nasal insert outlets  190  are located and extend through the proximal wall recess member  178 . Nasal insert outlets  190  provide an appropriately humidified O 2 /N 2  gas mixture from the generator  170  to the patient. 
         [0051]    Referring to  FIG. 1 , generator  170  preferably includes the following additional features as they relate to housing assembly  110  and retention cap  140 . Outer surface  182  of distal wall member  176  is preferably in continuous mechanical communication with spring  128  during operation of device  100 . 
         [0052]    Generator  170  preferably includes one guide rail  192  and stop rail  194  located on outer surface  184  of each vertical side member  180 . Rails  192  and  194  extend preferably along substantially the entire length of outer surface  184 , thereby extending from proximal surface  186  and to near distal surface  188 . Rails  192  and  194  can be located at any position along the dimension of vertical side member  180  of generator  170 . 
         [0053]    Referring to  FIG. 1 , rails  192  and  194  preferably have a dissimilar shape and size along at least a portion of their respective lengths. Guide rail  192  can have a substantially uniform size and shape throughout its length. Stop rail  194  includes a first stop sub-rail  196 , a second stop sub-rail  197  and an interface stop rail region  198  that is located between stop sub-rails  196  and  197 . Stop sub-rail  196  terminates at proximal surface  186  and at interface rail region  198 . Stop sub-rail  197  terminates at interface stop rail region  198  and preferably near distal surface  188 . Stop sub-rail  196  and stop sub-rail  197  preferably have substantially uniform size and shape throughout their respective lengths; however, with respective sizes and shapes of stop sub-rails  196  and  197  are differ with respect to each other. Stop sub-rail  196  can have a size and shape similar to that of guide rail  192 ; however, stop sub-rail  197  is preferably larger than stop sub-rail  196 . Interface stop rail region  198  can have an intermediate size and shape between those corresponding to stop sub-rails  196  and  198 . 
         [0054]    Guide rails  192  of generator  170  are configured by their size and shape to translationally slide freely (for example, without undue friction) in guide grooves  132  and  152  of housing assembly  110  and retention cap  140 , respectively, in device  100 . Stop sub-rails  196  is configured by their size and shape to translationally slide freely in stop grooves  134  and  154  of housing assembly  110  and retention cap  140 , respectively, in device  100 . However, stop sub-rails  197  are configured by their size and shape to translationally slide freely in only stop grooves  134  of housing assembly  110  and not stop groove  154  of retention cap  140  in device  100 . Depending upon the size and shape of interface stop rail region  198 , it may or may not translationally slide freely through stop groove  154  of retention cap  140 . Blocker  199  defines the position on generator  170  along which stop rail  194  cannot translationally slide freely past stop groove  154  of retention cap  140  in device  100 . 
         [0055]    Having described the structure and function of the guide grooves and rails, as well as stop grooves and rails, of device  100  ( FIG. 1 ), obvious permutations of their arrangement on housing assembly  110 , cap assembly  140  and generator  170  will be readily apparent based upon this disclosure. Such permutations include switching which components of device  100  include rails vs. grooves. It will be apparent that rails rather than grooves can be incorporated onto both housing assembly  110  and retention cap  140 , while grooves rather than rails can be incorporated onto generator  170 . 
         [0056]    As explained above, and with reference to  FIG. 1 , spring  128  is preferably in continuous mechanical communication with both housing  110  and generator  170  in device  100 . In that particular embodiment, spring  128  has only attachment point, where one end of spring  128  that is preferably connected to inner wall surface  118  of housing assembly  110 . In alternative embodiments, end of spring  128  can be connected to outer surface  182  of distal wall member  176  of generator  170  as its only attachment point with device  110 . 
         [0057]    In alternate embodiments of device  100 , however, spring  128  can be in continuously mechanical communication with only one member selected from housing assembly  110  and generator  170 . For example, embodiments of device  110  can include spring  128  suspended in housing assembly  110  by attachment of a midpoint of spring  128  to horizontal base member  112 . Other embodiments of device  110  can include spring  128  attached to outer surface  182  of distal wall member  176  of generator  170 . 
         [0058]    In the foregoing embodiments, such connections and attachments can be accomplished using any structure amenable for connecting spring  128  to these and other features of housing assembly  110  and/or generator  170  (such as inner wall surface  118 , horizontal base member  112  and outer surface  182 , among others) such as a recess; a pocket; one or more rods or like structures; immobilized tie-downs, such as clips, staples, sutures, tapes, wires, rivets and the like; an adhesive, such as glue, epoxy and the like; among others. Spring retention element  126  is preferably a recess located within inner wall surface  118 . 
         [0059]    In yet another embodiment, device  100  can be manufactured with spring  128  integrated into either housing assembly  110  or generator  170 . In such an embodiment, spring  128  can be a traditional spring that is insert molded into the plastics. 
         [0060]    In other embodiment, spring  128  can be a living spring that is made of plastic as part of one of housing assembly  110  or generator  170 . Spring  128  in this embodiment produces its force output as housing assembly  110  and generator  170  are slid together, and the interference forces the plastic to deflect. 
         [0061]    Spring  128  can be a spring of any configuration and composition, including an air spring, a coil spring, a helical spring, a leaf spring, wave spring and a torsional spring. 
         [0062]    However configured, for appropriate function within device  100  during active operation, spring  128  contacts both outer surface  182  of distal wall member  176  of generator  170  and inner wall surface  118  of housing assembly  110  to create compression between generator  170  and housing assembly  110  as a result of the force device  100  applies to the patient. Thus, spring  128  is in force communication with both housing assembly  110  and generator  170  during operation of device  100 . 
         [0063]    Referring to  FIG. 2 , device  100  is illustrated in assembled form. Pins  150  of retention cap  140  mate with pin holes  130  of housing assembly  110  to create securely fastened interface  160 . Preferably, pins  150  are slightly larger than pin holes so that they mate together by press fit to create interface  160 . An alternative approach can be used to create interface  160 , such as the use of an adhesive material to fill pin holes  130  before insertion of pins  150 . 
         [0064]    As explained previously, and in reference to  FIG. 1 , the preferred arrangement of the guide grooves and stop grooves, as well as their mated guide rails and stop rails, is in inverse relative orientation relative to the opposite vertical side wall members  116  and opposite vertical side wall members  144 . The offset arrangement of stop rails and stop grooves maintain the balance of generator  170  within housing assembly  110 , and further limits binding and preventing incorrect assembly of device  100 . 
         [0065]    Another preferred embodiment is illustrated in  FIGS. 3 and 4 . In  FIG. 3 , device  200  includes housing assembly  210  and generator  270 . In  FIG. 4 , device  200  is assembled with generator  270  located inside housing assembly  210 , wherein generator  270  is interlocked to housing assembly  210  at retaining member  260 . 
         [0066]    Device  200  includes similar features as presented for device  100  of  FIGS. 1 and 2 , except that retention cap  140  of device  100  is not required for device  200 . 
         [0067]    Housing assembly  210  of device  200  preferably includes the following features. Housing assembly  210  includes horizontal base member  212 , vertical distal wall member  214  and two vertical side wall members  216 . Horizontal base member  212  is preferably substantially plain surface. Vertical distal wall member  214  includes an inner wall surface  218 . Vertical side wall members  216  include inner wall surface  220 , outer wall surface  222  and proximal surface  224 . 
         [0068]    Spring retention element  226  accommodates spring  228 . Spring retention element  226  can be any structure amenable for retaining spring  228 , such as a recess; a pocket; one or more rods or like structures; immobilized tie-downs, such as clips, staples, sutures, tapes, wires, rivets and the like; an adhesive, such as glue, epoxy and the like; among others. Spring retention element  226  is preferably a recess located within inner wall surface  218 . Spring  228  is preferably in continuous mechanical communication with housing assembly  210  during operation of device  200 . 
         [0069]    Housing assembly  210  preferably includes two guide grooves  232  and one stop rail  234  located on inner surface  220  of each vertical side member  216 . Both guide groove  232  and stop rail  234  run along the inner wall surface  220  and terminate at proximal surface  224  and preferably at the junction of inner wall surface  220  with inner wall surface  218 . Retaining member  260  is positioned at the end of stop rail  234  terminated at proximal surface  224 . 
         [0070]    Grooves  232  can be located at any position along the dimension of vertical side member  216  of housing assembly  210 . Grooves  232  preferably flank rail  234  on the vertical dimension (that is, one glide groove  232  lies above and below stop rail  234 ). 
         [0071]    Referring to  FIGS. 3 and 4 , grooves  232  and rail  234  preferably have dissimilar sizes. Guide groove  232  preferably has a substantially uniform size and shape throughout its length that is smaller than the corresponding size and shape of stop rail  234 . The reason for stop rail  234  having an increased size throughout its length relative to guide groove  232  is attributed to the fact that stop rail  234  includes retention member  260  that provides the interlock feature for positively holding generator  270  inside housing assembly  210 . No such function is required of groove  232  in the embodiment of device  200 . 
         [0072]    Yet the shapes and sizes of grooves  232  and rail  234  need not be identical for their like counterparts on the opposing vertical side member  216 . But the shapes, sizes and locations of guide groove  232  and stop rail  234  for a given vertical side member  216  are preferably compatible to match with the shapes, sizes and locations of guide rails  292  and stop groove  294  of generator  270 . Such compatibility ensures that generator  270  can translationally slide freely relative to housing assembly  210  in device  200 . 
         [0073]    Generator  270  preferably includes two guide rail  292  and one stop groove  294  located on outer surface  284  of each vertical side member  280 . Rails  292  and  294  extend preferably along substantially the entire length of outer surface  284 , thereby extending from proximal surface  286  and to near distal surface  288 . Rails  292  and groove  294  can be located at any position along the dimension of vertical side member  280  of generator  270 . Rails  292  preferably flank groove  294  on the vertical dimension (that is, one glide rail  292  lies above and below stop groove  294 ). 
         [0074]    Referring to  FIG. 3 , stop groove  294  preferably have a dissimilar shape and size along at least a portion of its length. Stop groove  294  includes a first stop sub-groove  296 , a second stop sub-groove  297  and an interface stop groove region  298  that is located between stop sub-grooves  296  and  297 . Stop sub-groove  296  terminates at proximal surface  286  and at interface rail region  298 . Stop sub-groove  297  terminates at interface stop groove region  298  and preferably near distal surface  288 . Stop sub-groove  296  preferably have substantially uniform size and shape throughout its length. Stop sub-groove  297  preferably has a progressively increasing thickness along its length, wherein the thickness of sub-groove  297  at the near distal surface  288  is negligible (being substantially contiguous with the surface of outer surface  284 ), and wherein thickness of sub-groove  297  at the interface stop groove region  298  is substantial. The thickness of sub-groove  297  at the interface stop groove region  298  is sufficiently substantial so as to interlock generator  270  into housing assembly  210  when retaining member  260  of housing assembly  210  passes across the interface stop groove region  298 . 
         [0075]    Guide rails  292  of generator  270  are configured by their size and shape to translationally slide freely (for example, without undue friction) in guide grooves  232  of housing assembly  210  in device  200 . Stop sub-groove  296  is configured by their size and shape to translationally slide freely in stop rail  234  of housing assembly  210  in device  200 . However, stop sub-groove  297  is configured by its size and shape to translationally slide freely in stop rail  234  only until to interface stop groove region  298  encounters retaining member  260  of housing assembly  110 . Thus, interface stop groove region  298  acts as the functional equivalent of as blocker element because feature  298  defines the position on generator  270  beyond which generator  270  cannot translationally slide freely out of housing assembly  210  in device  200 . 
         [0076]    Once interlock between housing assembly  210  and generator  270  has occurred, device  200  is stably assembled for use. Device  210  can be readily disassembled by disengaging retention member  260  from interface stop groove region  298 . For this purpose, retention member  260  of stop rail  234  has some flexibility to enable it to pass over interface stop groove region  298  for disengagement. Such disassembly is conveniently performed to provide servicing and cleaning functions to the underlying components. In general, however, device  200  is not disassembled during operation. 
         [0077]    Having described the structure and function of the guide grooves and rails, as well as stop grooves and rails, of device  200  ( FIGS. 3-4 ), obvious permutations of their arrangement on housing assembly  210  and generator  270  will be readily apparent based upon this disclosure. Such permutations include switching which components of device  200  include rails vs. grooves. It will be apparent that the appropriate combinations of rails and grooves can be incorporated onto both housing assembly  210  and generator  270  so that retaining member  260  is resides on generator  270  and that interface stop groove region  298  is incorporated on housing assembly  210 . 
       Rails: Alternative Embodiments. 
       [0078]    Preferred embodiments feature rail elements on both sides of device subcomponents that are offset. The offset rails provide a benefit of preferred manufacturing process by preventing the device from being assembled incorrectly. In other embodiments, symmetrical rails that are not offset can be incorporated into device subcomponents. 
         [0079]    Referring to  FIG. 5 , embodiment of device  300  can be devoid of rails altogether. Housing assembly  310  of device  300  preferably includes the following features. Housing assembly  310  includes horizontal base member  312 , vertical distal wall member  314  and two vertical side wall members  316 . Horizontal base member  312  is preferably substantially plain surface. Vertical distal wall member  314  includes an inner wall surface  318  and top surface  319 . Vertical side wall members  316  include inner wall surface  320 , outer wall surface  322 , a proximal surface  324 , and top cap  325 . 
         [0080]    Generator  370  of device  300  preferably includes the following features. Generator  370  includes top surface member  372 , bottom surface  374 , distal wall member  376 , a proximal wall recess member  378  and two vertical side wall members  380 . Distal wall member  376  includes outer surface  382  and top surface  383 . Vertical side wall members  380  include outer surface  384 , proximal surface  386 , distal surface  388  and top surface  389 . 
         [0081]    In this latter design implementation, top cap  325  would be required to contain generator  370  within housing assembly  310 . A preferred design for this implementation includes top cap  325  on both vertical side wall members  316  of housing assembly  310  which preferably is in mechanical communication with top surface member  372  of generator  370  to retain generator  370  within housing assembly  310 . 
       Operational Indicator 
       [0082]    Referring again to  FIG. 1 , outer surface  182  preferably includes indicator  191  having first indicator zone  193  and second indicator zone  195  arranged adjacent to one another. First indicator zone  193  is located in the proximal region of outer surface  182  while second indicator zone  195  is located in the distal region of outer surface  182 . First indicator zone  193  preferably differs from second indicator zone  195  so that the patient or another attending the patient can determine readily and quickly whether device  100  is safely operating. 
         [0083]    For example, common head-straps attached to head-strap elements  136  after device is attached to the patient&#39;s nasal passage are tightened around the patient&#39;s head. Indicator  191  is preferably used to determine the extent to which the head straps are tightened is based upon the relative force applied by the user compared to the tension created by spring  128 . Thus, indicator  191  provides an indication to the user when the amount of force applied through the tightening of the head-strap is unsafe and likely to cause harm to the patient. As generator  170  is compressed into housing assembly  110 , indicator  191  will slide from first indicator zone  193  to second indicator zone  195 . First indicator zone  193  represents unsafe tension being applied to the head-strap while second indicator zone  195  represents safe tension being applied to the head-strap. 
         [0084]    In yet another embodiment of device  100 , indicator  191  can be placed on housing assembly  110  rather than on generator  170 . Because generator of device  100  moves internally to housing assembly  110 , translucent or optically transparent materials are preferably used for manufacturing housing assembly  110  so that movement of generator  170  relative to indicator  191  (and indicator zones  193  and  195 ) may be viewed through housing assembly  110 . 
         [0085]    Referring to  FIGS. 3 and 4 , embodiment of device  200  preferably includes viewing window  217  in at least one vertical side wall member  216  of housing assembly  210  to enable viewing of indicator  291  on generator  270 . In this design, viewing window  217  on housing assembly  210  allows visualization of only one section of indicator  291  at once. This simplifies indicator  291  for the user, such that any appearance of second indicator zone  295  (for example, a color such as green or symbol for a “A-OKAY” marker) is an immediate warning of high forces, as opposed to lack of indicator zone  293  (for example, a color such as read or symbol for a “failing” marker). This also moves indicator  291  to the back of device  210  which prevents it from being obstructed or hidden by the head strap assembly attached at  236 . 
         [0086]    Indicator  191  ( 291 ) serves to inform attendants when high forces are being exerted on the patient&#39;s nasal septum as a result of the patient moving or device  100  ( 200 ) slipping while attached. Thus indicator  191  ( 291 ) provides a visual alarm critical to preventing prolonged exposure and potential breakdown of a patient&#39;s nasal septum. 
         [0087]    Beside visual indicators, other embodiments of indicators include other sensory output implementations. For example, an audible indicator can provide one or more audible sounds that inform about device functions. A preferred audible indicator emits a sound that warns about unsafe operation conditions for the device. Another example of a sensory indicator is a vibration mode indicator. This type of indicator emits one or more vibrations preferably sensed by the patient. A preferred vibration mode indicator emits a vibration that warns about unsafe operation conditions for the device. Sensory indicators are preferably triggered by a motion sensor located on the device detecting the relative position of the generator relative to the housing assembly. Motion sensors having visual, audible, and vibrational outputs are well known in the art and can be incorporated into the devices disclosed herein. 
       Force Gauged Assembly Enclosures for Commercial CPAP Generators 
       [0088]    Embodiments disclosed herein are adaptable for use with generators produced from commercial manufactures. Accordingly, force gauged assembly enclosures having a plurality of features are within the scope of the devices disclosed herein. Those devices include a plurality of supporting members, such as guide elements, stop elements, spring elements, and visual indicator elements. Depending upon the generator manufacturer&#39;s requirements and generator implementations, force gauged assembly enclosures comprising any of the disclosed embodiments may be configured to provide the requisite force gauge measurement capabilities. 
       Maximum Force Indicator 
       [0089]    Referring to  FIG. 6A , device  400  provides another embodiment of a force gauge device. Device  400  includes housing assembly  410  and generator  470 . 
         [0090]    Housing assembly  410  of device  400  preferably includes the following features. Housing assembly  410  includes horizontal base member  412 , vertical distal wall member  414  and two vertical side wall members  416 . Horizontal base member  412  is preferably substantially plain surface. Vertical distal wall member  414  includes an inner wall surface  418 . At least one push-block member  415  is preferably coupled to inner wall surface  418 . Push-block member  415  preferably established communication throughout the side-to-side length of distal vertical distal wall member  414 . Push-block member  415  preferably is coupled to the outer surface  482  of distal wall member  476  of generator  470 . 
         [0091]    Referring to  FIG. 6B , housing assembly  410  components vertical side wall members  416  and/or basement members  412  include at least two and preferably four more cavities  420  that preferably receive support rods  422 . Distal vertical wall member  414  preferably displaceable from the remaining components of housing assembly  410 , including horizontal base member  412  and both vertical distal wall members  414 . Support rods  422  preferably are affixed to inner wall surface  418  and/or to base member  412 . To couple distal vertical wall member  414  to horizontal base member  412  and both vertical distal wall members  414 , support rods  422  are disposed into cavities  420 . The support rods further include a plurality of measuring indications  426 . 
         [0092]    Housing assembly  410  thus includes a displaceable distal vertical wall member  416  that retains coupling to the remainder of housing assembly  410  by support rods  422  being disposed within cavities  420 . The initial position of the distal wall member  416  is preferably proximal to base member  412  and side wall member  416 . 
         [0093]    Referring to  FIG. 6A , assembly of generator  470  into housing assembly  410  preferably does not alter the location of distal wall member  416  relative to the base member  412  and side wall member  416 . Likewise, low level compressions preferably do not displace distal wall member  414  from the remainder of housing assembly  410 . 
         [0094]    Referring to  FIG. 6B , when generator  470  is compressed significantly into housing assembly  410 , generator  470  enters the interior cavity of housing assembly  410 , and distal wall member  476  of generator  470  actively pushes against push-block member(s)  415 . Because push-block members  415  are coupled to distal wall member  414 , the compression force of generator  470  preferably displaces distal wall member  414  away from the remainder of the housing assembly  410  by movement of the support rods  422 . 
         [0095]    The extent to which generator  470  exerts force against push-block(s)  415  will be directly related to the extent to which support rods  422  are exposed from cavities  420 . The support rods  422  preferably have slight friction coefficient when disposed into cavities  420 , so as to provide a memory effect of the extent to which the plurality of measuring indications  426  are exposed for counting. Thus, the support rods  422  remain extended even after generator  470  relaxes and the compression ceases ( FIG. 6C ). 
         [0096]    Housing assembly  410  includes a retention member  460  to maintain generator  470  inside housing assembly  410 . One preferred retention member  460  includes snap-fit interlocks with generator  470  similar to other interlocking features disclosed herein. For example, retaining member  460  located on the inner surface  420  of housing assembly  410  preferably can form the interlock by passing across a suitable opposing snap-fit feature located on the outer surface interface stop groove region  298  located on an outer surface  284  of vertical wall  280  of generator  470 . Another preferred retention member  460  includes a retention cap, like cap  140 . 
       Manufacturing Considerations: Best Mode 
       [0097]    Embodiments of device  200 , and obvious variations thereof, is preferred over embodiments of device  100 . Manufacturing considerations led to device  200  as the preferred design choice. Basic production principles were applied, including limiting the number of components, and design for ease of molding. These changes led to removal of retention cap  140  from a preferred device design in favor of snap-fit, interlocking features of retention member  260  and element  298  for housing assembly  210  and generator  270 . In addition, retaining features across the top of the housing are preferably relieved to allow for injection molding of the housing assembly by removing undercut feature. The rails are preferably kept in off-set locations so that the device cannot be assembled backwards or inverted. 
       Device Adaptability to Multiple Commercially Available Generators. 
       [0098]    Many commercial CPAP generator devices are available that use a variety of nasal inserts (or patient contacting inserts). These generators typically include variations among both nasal prongs and masks. Embodiments of the housing components for the device are amenable to modification modified to match the specific geometry requirements of which ever generator(s) the manufacturing company would prefer. 
         [0099]    The following non-limiting example illustrates the operations of the various sampling systems described herein. The following example generally employs modules and subsystems of the type shown in  FIGS. 1 and 3 . 
       EXAMPLES 
       [0100]    Two tests were run to determine the effectiveness of a preferred embodiment (“prototype”). The first test determined if the preferred embodiment&#39;s air system performed effectively and the second test measured the force produced on the nose and septum of the infant when the nasal interface was attached. 
       Example 1 
     Airflow Test Protocol 
       [0101]    A test was run to determine the effectiveness of a preferred embodiment (“prototype”). The test measured the force produced on the nose and septum of the infant when the nasal interface was attached. 
       Force Test Protocol 
       [0102]    The force test was conducted using a specially designed fixture (model test doll). This fixture was based on a doll that was similar to the model used by nurses during training. It was modified to include a pre-calibrated force transducer that was placed in line with the doll&#39;s septum. The signal from the transducer was then amplified using an inverting amplifier made using a 741 opamp. Nurses were asked to attach both the Airway&#39;s device and prototype to the doll four times each in order to determine the amount of force applied. The testing was conducted in a randomized order to prevent a potential learning curve, or familiarity with the fixture, which could bias the data. For each trial a peak force and steady state force was measured. The steady state force was defined as the average force production for the final five seconds of the trial, after the device is attached, and the fixture is left untouched for five seconds. 
       Test Results—Force 
       [0103]      
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Mean and Standard Deviation of Force Data. 
               
             
          
           
               
                   
                 PEAK 
                 STEADY 
               
             
          
           
               
                 DEVICE 
                 Mean (lbf) 1   
                 SD (lbf) 
                 Mean (lbf) 
                 SD (lbf) 
               
               
                   
               
             
          
           
               
                 Prior Art (Airway) 
                 0.1317072 
                 0.185157 
                 0.03749 
                 0.036811 
               
               
                 Prototype 
                 0.0691347 
                 0.055284 
                 0.024032 
                 0.016171 
               
               
                   
               
               
                   1 lbf, pound force. 
               
             
          
         
       
     
         [0104]    When looking at the data (see  FIG. 7 ), the force applied when using the prototype is lower on average than the force applied when using the Airlife device. It is important to note that by looking at the mean and standard deviation of the data, the standard deviation is much smaller and the spread of the histogram for the prototype is much tighter for the prototype than for the Airlife device. This is very important and promising because it shows that the prototype is more consistent and most importantly avoids extreme outliers (see  FIG. 7C ) that can potentially damage the infant&#39;s septum. 
         [0105]    Overall, the data shows that the force applied is lower for the prototype on average. This trend shows proof of concept. 
       DEFINITIONS 
       [0106]    When introducing elements of aspects of the embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The word “or” means any one member of a particular list and also includes any combination of members of that list, unless otherwise specified. 
         [0107]    The modal verb “may” refers to the preferred use or selection of one or more options or choices among several described embodiments or features contained within the same. Where no options or choices are disclosed regarding a particular embodiment or feature contained in the same, the modal verb “may” refers to an affirmative act regarding how to make or use an aspect of a described embodiment or feature contained in the same, or a definitive decision to use a specific skill regarding a described embodiment or feature contained in the same. In this latter context, the model verb “may” has the same meaning and connotation as the auxiliary verb “can.” 
         [0108]    The term “about” is used herein to mean approximately, roughly, around, or in the region of When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. Preferably, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 20 percent up or down (higher or lower). 
         [0109]    The term “guide element” refers to one or more members that couple one or more structures together so that the two structures are slideably engaged, translationally engaged or display the capability of sliding or translating along a path. An example of a guide element is a guide rail or a guide groove. 
         [0110]    The term “stop element” refers to one or more members that couple one or more structures together so that the two structures are prevented during one aspect of their coupling path from being slideably engaged, translationally engaged or display the capability of sliding or translating along a path. An example of a stop element is a stop rail or a stop groove. While a stop element might display functional attributes of a guide element, one or more structural features of a stop element prevents the stop element from displaying the full extent of being slideably engaged, translationally engaged or display the capability of sliding or translating along a path. 
         [0111]    Not all of the depicted components illustrated or described may be required. In addition, some implementations and embodiments may include additional components. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional, different or fewer components may be provided and components may be combined. Alternatively or in addition, a component may be implemented by several components. 
         [0112]    The above description illustrates the invention by way of example and not by way of limitation. This description clearly enables one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. Additionally, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it will be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
         [0113]    Having described aspects of the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of aspects of the invention as defined in the appended claims. As various changes could be made in the above constructions, products, and methods without departing from the scope of aspects of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
         [0114]    The technical effects and technical problems in the specification are exemplary and are not limiting. It should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.