Abstract:
Hose connection system for narially sensitive diagnostic devices. At least some of the illustrative embodiments are systems including a test device and a nasal cannula. The test device includes a first port configured to sense an attribute of airflow, and a second port configured to sense an attribute of airflow. The nasal cannula includes a first hose configured to fluidly couple on a device-end to the first port (and the first hose configured to fluidly couple between the first port and a first naris of a patient), and a second hose configured to fluidly couple on a device-end to the second port (and the second hose configured to fluidly couple between the second port and a second naris of the patient). The nasal cannula is configured such that the first hose only couples to the first port and the second hose only couples to the second port.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of provisional application Ser. No. 60/803,560 filed May 31, 2006, titled “Hose connection system for narially sensitive diagnostic devices,” which application is incorporated by reference herein as if reproduced in full below. 
    
    
     BACKGROUND 
     Sleep disordered breathing is common throughout the population, and some sleep disorders may be attributable to disorders of the respiratory tract. Sleep apnea may be a disorder where a person temporarily stops breathing during sleep. A hypopnea may be a period of time where a person&#39;s breathing becomes abnormally slow or shallow. In some cases, a hypopnea precedes an apnea event. Snoring may be caused by mucus build up in the upper respiratory tract, and/or excessive tissue causing cyclic full or partial blockages of the nose. Other breathing difficulties, not necessarily related to sleep but which breathing difficulties become more pronounced during sleep, may be caused by full or partial blockages of the nares, such as by a tumor or polyp. 
     Sleep disordered breathing and other breathing difficulties may be diagnosed in a sleep lab, or possibly by a device which the patient takes home and wears throughout the day or during sleep. For a proper diagnosis, particularly in the case of a tumor or polyp, the various ports of a test device need to be coupled to the naris for which they were intended; however, currently available nasal cannulas have device-ends (as opposed to patient-ends) that are identical and easily switched when being coupled to a test device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of the preferred embodiments of the invention, reference will now be made to tie accompanying drawings in which: 
         FIG. 1  illustrates a system in accordance with embodiments of the invention; 
         FIG. 2  illustrates hose connections in accordance with some embodiments; 
         FIG. 3  illustrates hose connections in accordance with some embodiments; 
         FIG. 4  illustrates hose connections that also identify the mask, in accordance with some embodiments; 
         FIG. 5  illustrates an electrical circuit in accordance with some embodiments; 
         FIG. 6  illustrates an electrical circuit in accordance with some embodiments; 
         FIG. 7  illustrates hose connections in accordance with some embodiments; and 
         FIG. 8  illustrates hose connections in accordance with some embodiments. 
     
    
    
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claims to refer to particular system components. However, manufacturing companies may refer to various components by different names. This document does not intend to distinguish between components that differ in name but not function. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a system  1000  in accordance with embodiments of the invention. In particular,  FIG. 1  illustrates a test device  10 . The test device  10  may be a device for sensing airflow used in a dedicated sleep lab or a hospital, or the test device  10  may be a portable possibly battery operated) device that a patient uses in their home which is used as an initial diagnostic aid in diagnosing breathing difficulties. The test device  10  may be, for example, a device such as described in issued U.S. Pat. No. 7,066,180, titled “Method and System for Measuring Airflow of Nares,” which patent is incorporated by reference herein as if reproduced in full below. 
     The individual fluid couplings between the test device  10  and the patient  12  may be by way of a bifurcated nasal cannula  20 , such a cannula having two fluidly independent pathways running between the test device  10  and the patient  12 . The patient&#39;s right naris fluidly couples to a right naris port  16  and the left naris fluidly couples to a left naris port  18 . 
     Still referring to  FIG. 1 , the test device  10  in accordance with at least some embodiments of the invention has the ability to log information about the absolute and/or relative inspiratory and expiratory airflow. The information regarding the inspiratory and expiratory airflow may be helpful in diagnosing certain ailments (e.g., existence of a tumor or polyp in a particular naris, head position dependent valve collapse in a particular naris). For the log to be most beneficial in diagnosis, the output port  16  for the right naris should be coupled to the right naris, and the output port  18  for the left naris should be coupled to the left nails. In accordance with at least some embodiments, the test device  10  and the bifurcated nasal cannula  20  work together to ensure that the hose for the right nails only couples to the outlet port  16  for the right naris, and the hose for the left naris only couples to the outlet port  18  for the left naris. 
     Ensuring the proper coupling of the bifurcated nasal cannula  20  and the test device  10  may take many forms. In some embodiments, each hose of the bifurcated nasal cannula has a device-end (i.e., the end that couples to the test device) fitting that mates only with the appropriate outlet port.  FIG. 2  illustrates a system where the device-end fittings ensure proper orientation. In particular,  FIG. 2  illustrates a partial view of an exterior  24  of a test device  10 . The illustrative exterior has two outlet ports  16  and  18 , which in these embodiments comprise apertures  26  and  28 . The apertures  26  and  28  fluidly couple to devices internal to the test device  10 , such as pressure sensors and/or flow sensors.  FIG. 2  also illustrates a portion of the bifurcated nasal cannula  20  comprising a first hose  30  and a second hose  32 . Each of the hoses  30  and  32  have a device-end fitting  34  and  36  respectively. As illustrated in  FIG. 2 , the device-end fitting  34  is configured to fluidly couple to the aperture  26 , but because of the difference in aperture shape the device-end fitting  34  will not couple to the aperture  28 . Likewise, the device-end fitting  36  is configured to fluidly couple to the aperture  28 , but because of the difference aperture shape the device-end fitting  36  will not fluidly couple the aperture  26 . In this way, the bifurcated nasal cannula  20  cannot be fluidly coupled to the test device  10  in a reverse order. While  FIG. 2  shows an illustrative square aperture  26  and circular aperture  28  (and corresponding device-end fittings  34  and  36 ), other shapes and configurations may be equivalently used. For example, the test device  10  may have one male press-fit (Luer) fitting and one female Luer fitting, with the bifurcated nasal cannula having mating Luer fittings. Any structural differences between the two hose connections that reduces the possibility of misconnecting hoses of the bifurcated nasal cannula  20  to the test device  10  may be equivalently used. 
       FIG. 3  illustrates alternative embodiments that ensure proper coupling of the bifurcated nasal cannula  20  to the test device  10 . In particular,  FIG. 3  illustrates a partial view of the exterior  24  of the test device  10 . The illustrative exterior has two outlet ports  16  and  18 , which in these embodiments comprises male connections  40  and  42 , respectively. Female connections may be equivalently used. The illustrative exterior  24  also has a key aperture  44 . The connections  40  and  42  couple one each devices to internal to the test device  10 , such as pressure sensors and/or flow sensors.  FIG. 3  also illustrates a portion of the bifurcated nasal cannula  20  comprising a first hose  30  and second hose  32 . A bracket  46  mechanically (though not fluidly) couples the hoses  30  and  32  together on the device end  48 . Each of the hoses  30  and  32  has a device-end fitting  50  and  52 , respectively; however, the device-end fittings  50  and  52  may be similar in these embodiments because the bracket  46  and a tab  54  work together with the aperture  44  in the test device  10  to ensure that the house is coupled in only one orientation. 
     As illustrated in  FIG. 3 , the key aperture  44  is positioned off center with respect to the outlet ports  16  and  18 . Likewise, the tab  54  coupled to the bracket  46  is positioned off center with respect to the bracket  46 . In this way, the device end  48  of the hose system  20  couples the hoses  30  and  32  to their respective outlet ports  16  and  18  in only one orientation—the orientation where the tab  54  extends into the key aperture  44 . If a user attempts to fluidly couple the hoses  30  and  32  to the test device in a reverse orientation, the key aperture  44  will not align with the tab  54 , and thus the hose system  20  will not fluidly couple to the test device  10 . The long dimension of the key aperture  44 , and correspondingly the long dimension of the tab  54 , may be equivalently oriented at any angle. In alternative embodiments, the key aperture  44  and the tab  54  may equivalently use other corresponding shapes (e.g. circular, square, hexagonal), so long as the key aperture  44  and tab  54  allow the hose system  20  to fluidly couple to hoses  30  and  32  to the ports  16  and  18  in only one orientation. Moreover, the key aperture  44  and tab  54  need not be disposed between the outlet ports  16  and  18 , and thus the key aperture  44  and the tab  54  may be equivalently above, below or outside the outlet ports  16  and  18  so long as the hose system  20  couples to the outlet ports  16  and  18  in only one orientation. Further still, the key aperture  44  and tab  54  may be centered between the ports, but the shape of the key aperture  44  and tab  54  may enable coupling in only one orientation. 
     When using test device  10  as a diagnostic aid, the pressures and/or airflows sensed may be relative. That is, for example, if measuring pressure as indicative of a patient&#39;s respiratory function, the pressure in each tube of the bifurcated nasal cannula is created by air being hydraulically forced into each tube during exhalation. Likewise, lower pressure associate with inhalation is created by air flowing past the patient end of the nasal cannula into the patient&#39;s nares. The amount of pressure created in each case may be dependent not only upon the respiratory effort of the patient, but also on characteristics of the hoses (e.g., inside diameter), and thus identifying the manufacturer/type of bifurcated nasal cannula may be important. Likewise in situations where airflow through the nasal cannula is sensed, exhalation by the patient causes airflow through each tube and out an atmospheric vent of the test device. Inhalation draws air through each tube. The amount of airflow, and thus the amount sensed by the test device, may be dependent not only upon respiratory effort of the patient, but also on characteristics of the hoses (e.g., internal diameter, length), and thus identifying the manufacture/type of bifurcated nasal cannula may be important. 
       FIG. 4  illustrates embodiments where the bifurcated nasal cannula  20  identifies its manufacturer and/or type. In particular, the tab  54  of the bracket  46  has features that identify the bifurcated nasal cannula to which the hoses  30  and  32  couple. The term “features” in this specification and in the claims is used broadly to encompass not only physical features (e.g., aperture  60  or notch  62 ), but the term features also comprises any mechanism that identifies the nasal mask (e.g., embedded electronic device  64 ). The embedded electronic device  64  in some embodiments is a serial read only memory (ROM) which electronically couples to and communicates with a processor of the bilateral positive airway pressure device by way of electrical contacts  66 . In alternative embodiments, the embedded electrical device  64  is a radio frequency identification (RFID) tag which is read by the bilateral positive airway pressure device. In yet further alternative embodiments, the tab  54  has identifying indicia on its outer surface, such as a color coding scheme or bar code, that is read by the processor of the test device  10 . Notice also that in addition to supporting the features which identify the nasal cannula, the tab  54  can also serve the purpose of ensuring that the cannula couples to the test device in only one orientation, as discussed above. 
       FIG. 5  illustrates a circuit  70  which couples to an illustrative processor  73 . The processor  73  performs, in whole or in part, the diagnosis or pre-diagnosis performed by the test device  10 . The circuit  70  illustrated in  FIG. 5  may be part of the test device  10 , and is enabled for use with features of the tab  54  being aperture  60  and/or notch  62 . In particular, the circuit  70  comprises light emitting diodes  72  and  74 . Electrical current supplied from source  76  flows through the diodes creating light (not necessarily visible). The light from the light emitting diode  72  and  74  is configured to shine across the aperture, the aperture illustrated by dashed line  44 . The circuit  70  further comprises photo diodes  76  and  78 . Photo diodes  76  and  78  are arranged to be in operational relationship with the light emitting diode  72  and  74  respectively. While the illustrative circuit of  FIG. 5  shows only two light detection paths, any number of light emitting diodes and photo diodes implementing any number of light detection paths may be equivalently used. As the tab  54  is inserted through the key aperture  44 , the light path between the corresponding light emitting diode and photo diode is selectively broken, and the type of nasal cannula to which the hose system  20  is attached may be identified by the pattern of broken and unbroken lights paths. For example, if the light path between the light emitting diode  72  and photo diode  76  is broken, the photo diode  76  ceases conducting, and therefore the processor  73  sees a low voltage or logic zero input. Likewise, if the tab  54  has an aperture  60  or notch  62  such that the light path is unbroken in spite of the presence of the tab  54 , the photo diode conducts and the processor  73  sees a high voltage or a logic one. In the illustrative case of  FIG. 5  having two light paths, three different nasal cannulas may be identified (assuming that two unbroken light paths indicate that no cannula has been connected to the test device). 
       FIG. 6  illustrates alternative embodiments where the feature used to identify the nasal cannula is an RFID tag. In particular, the system  80  comprises a tag antenna  82  coupled to a RFID reader  84 . The RFID reader  84  and tag antenna  82  work together to interrogate an RFID tag coupled on the device end of a nasal cannula. In some embodiments, the RFID tag may reside on the tab  54 , and thus the antenna  82  may be in operational relationship to the aperture  44 . In other embodiments, the RFID tag may reside at any location proximate to the device-end of the cannula. Once the data payload of the RFID tag is read by the RFID reader, the RFID reader passes the information along to the processor  73  which may then compensate readings based on the physical characteristics of the cannula. 
     The various embodiments discussed to this point are based on use of a bifurcated (two-tube) cannula. In alternative embodiments, the test device  10  may also monitor airflow through a patient&#39;s mouth, and thus a three-tube cannula may be used. U.S. Pat. No. 7,007,694 titled “Nasal Cannula,” assigned to the same assignee as this specification and incorporated by reference herein as if reproduced in full below, is illustrative of a nasal cannula that may be used to monitor respiratory airflow through a patient&#39;s nares and mouth. It may as important to properly couple the tube associated with the mouth to a proper port on the test device  10 .  FIG. 7  illustrates system where device-end fittings of a three-tube cannula ensure proper orientation. In particular,  FIG. 7  illustrates a partial view of an exterior  24  of a test device  10 . The illustrative exterior in these embodiments has three outlet ports  16 ,  18  and  90 , which in these embodiments comprise apertures  26 ,  28  and  92 . The apertures  26 ,  28  and  92  fluidly couple to devices internal to the test device  10 , such as pressure sensors and/or flow sensors.  FIG. 7  also illustrates a portion of the bifurcated nasal cannula  100  comprising a first hose  30 , a second hose  32  and a third hose  94 . Each of the hoses  30 ,  32  and  94  has a device-end fitting  34 ,  36  and  96 , respectively. As illustrated in  FIG. 7 , the device-end fitting  34  is configured to fluidly couple to the aperture  26 , but because of the difference in aperture shape the device-end fitting  34  will not couple to the apertures  28  or  92 . Likewise, the device-end fitting  36  is configured to fluidly couple to the aperture  28 , but because of the difference aperture shape the device-end fitting  36  will not fluidly couple the aperture  26  or  92 . Finally, the device-end fitting  96  is configured to fluidly couple to the aperture  92 , but because of the difference in aperture shape the device-end fitting  96  will not fluidly couple to apertures  26  and  28 . In this way, the three-tube cannula  100  cannot be fluidly coupled to the test device  10  in an incorrect order. While  FIG. 7  shows an illustrative aperture shapes, other shapes and configurations may be equivalently used. 
       FIG. 8  illustrates alternative embodiments that ensure proper coupling of the three-tube cannula  100  to the test device  10 . In particular,  FIG. 8  illustrates a partial view of the exterior  24  of the test device  10 . The illustrative exterior has three outlet ports  16 ,  18  and  102 , which in these embodiments comprises male connections  40 ,  42  and  104 , respectively. Female connections may be equivalently used. The connections  40 ,  42  and  104  couple one each devices to internal to the test device  10 , such as pressure sensors and/or flow sensors.  FIG. 8  also illustrates a portion of the three-tube nasal cannula  100  comprising a first hose  30 , second hose  32  and third hose  106 . A bracket  108  mechanically (though not fluidly) couples the hoses  30 ,  32  and  106  together on the device-end  48 . Each of the hoses  30 ,  32  and  106  has a device-end fitting  50 ,  52  and  110 , respectively; however, the device-end fittings may be similar in these embodiments because the bracket  108  and placement of the hoses on the bracket  108  work together with the test device  10  to ensure that the house is coupled in only one orientation. In particular, the middle hose is offset from the center such that cannula  100  couples to the test device  10  in only one orientation. Although illustrative  FIG. 8  shows the hoses to be co-planar, in alternative embodiments the hoses may reside at different elevations, and indeed the different elevations may ensure that the hoses couples to the test device in only one orientation. Moreover, although a tab on the bracket and corresponding aperture in the test device are not strictly needed in the embodiments of  FIG. 8 , a tab may nonetheless be used as the mechanism to identify the cannula, as discussed above. 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. For example, ensuring the hoses connect in only one orientation may involve each connection comprising a male-type connector having a different diameter. Thus, while one hose may physically fit over a connector designed for a smaller diameter hose, the larger diameter hose will not seal, thus informing the user inappropriateness of the connection. It is intended that the following claims be interpreted to embrace all such variations and modifications.